0001628280-21-002865 | 10-K | XBRL Viewer | Esperion Therapeutics INC

Cover Page - USD ($) $ in Millions	12 Months Ended
Cover Page - USD ($) $ in Millions	Dec. 31, 2020	Feb. 01, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-35986
Entity Registrant Name	Esperion Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-1870780
Entity Address, Address Line One	3891 Ranchero Drive, Suite 150
Entity Address, City or Town	Ann Arbor
Entity Address, State or Province	MI
Entity Address, Postal Zip Code	48108
City Area Code	734
Local Phone Number	887-3903
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	ESPR
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,410
Entity Common Stock, Shares Outstanding		27,942,612
Documents Incorporated by Reference	Part III of this Annual Report on Form 10-K incorporates by reference information from the definitive Proxy Statement for the registrant’s 2021 Annual Meeting of Shareholders, which is expected to be filed with the Securities and Exchange Commission not later than 120 days after the Registrant’s fiscal year ended December 31, 2020.
Entity Central Index Key	0001434868
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 304,962	$ 166,130
Restricted cash	0	928
Short-term investments	0	34,651
Prepaid clinical development costs	844	6,081
Inventories	16,136	0
Other prepaid and current assets	23,954	3,924
Total current assets	345,896	211,714
Property and equipment, net	1,276	1,145
Intangible assets	56	56
Total right of use operating lease assets	6,030	1,532
Total assets	353,258	214,447
Current liabilities:
Accounts payable	51,975	28,856
Accrued clinical development costs	7,663	17,511
Other accrued liabilities	24,790	11,871
Revenue interest liability	5,392	5,236
Deferred revenue from collaborations	1,662	2,152
Operating lease liabilities	2,587	454
Total current liabilities	94,069	66,080
Convertible notes, net of issuance costs	179,367	0
Revenue interest liability	171,212	127,308
Operating lease liabilities	3,454	1,109
Other long-term liabilities	1,290	0
Total liabilities	449,392	194,497
Commitments and contingencies (Note 6)
Stockholders’ (deficit) equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized and no shares issued or outstanding as of December 31, 2020 and December 31, 2019	0	0
Common stock, $0.001 par value; 120,000,000 shares authorized as of December 31, 2020 and December 31, 2019; 27,910,366 shares issued at December 31, 2020 and 27,497,911 shares issued and outstanding at December 31, 2019	26	27
Additional paid-in capital	797,655	715,166
Treasury stock, at cost; 1,994,198 shares at December 31, 2020	(54,998)	0
Accumulated other comprehensive gain	0	23
Accumulated deficit	(838,817)	(695,266)
Total stockholders' (deficit) equity	(96,134)	19,950
Total liabilities and stockholders' (deficit) equity	$ 353,258	$ 214,447

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	27,910,366	27,497,911
Common stock, shares outstanding (in shares)		27,497,911
Treasury stock (in shares)	1,994,198

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total Revenues	$ 227,547	$ 148,364	$ 0
Operating expenses:
Cost of goods sold	2,392	0	0
Research and development	146,936	175,611	171,488
Selling, general and administrative	199,615	65,854	33,097
Total operating expenses	348,943	241,465	204,585
Loss from operations	(121,396)	(93,101)	(204,585)
Interest expense	(22,670)	(8,120)	(28)
Other income, net	515	4,056	2,803
Net loss	$ (143,551)	$ (97,165)	$ (201,810)
Net loss per common share - basic and diluted (in dollars per share)	$ (5.23)	$ (3.59)	$ (7.54)
Weighted-average shares outstanding (basic and diluted) (in shares)	27,473,873	27,090,284	26,754,308
Other comprehensive (loss) gain:
Unrealized (loss) gain on investments	$ (23)	$ 342	$ 526
Total comprehensive loss	(143,574)	(96,823)	(201,284)
Product
Revenues:
Total Revenues	12,965	0	0
Collaboration Revenue
Revenues:
Total Revenues	$ 214,582	$ 148,364	$ 0

Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Treasury Stock
Balance (in shares) at Dec. 31, 2017		26,304,669
Balance at Dec. 31, 2017	$ 244,691	$ 26	$ 641,801	$ (396,291)	$ (845)	$ 0
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (in shares)		356,809
Exercise of stock options	11,743	$ 1	11,742
Exercise of warrants (in shares)		159,944
Exercise of warrants	0
Vesting of restricted stock units (in shares)		3,437
Vesting of restricted stock units	0
Stock-based compensation	23,968		23,968
Other comprehensive gain (loss)	526				526
Net loss	(201,810)			(201,810)
Balance (in shares) at Dec. 31, 2018		26,824,859
Balance at Dec. 31, 2018	79,118	$ 27	677,511	(598,101)	(319)	0
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (in shares)		649,529
Exercise of stock options	11,771	$ 0	11,771
Exercise of warrants (in shares)		5,813
Exercise of warrants	0
Vesting of restricted stock units (in shares)		17,710
Vesting of restricted stock units	0
Stock-based compensation	25,884		25,884
Other comprehensive gain (loss)	342				342
Net loss	$ (97,165)			(97,165)
Balance (in shares) at Dec. 31, 2019	27,497,911	27,497,911
Balance at Dec. 31, 2019	$ 19,950	$ 27	715,166	(695,266)	23	0
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (in shares)	299,435	299,435
Exercise of stock options	$ 6,634	$ 1	6,633
Vesting of restricted stock units (in shares)		113,020
Vesting of restricted stock units	0
Stock-based compensation	28,385		28,385
Other comprehensive gain (loss)	(23)				(23)
Equity component of convertible notes	93,475		93,475
Repurchase of common stock under prepaid forward contract (in shares)		(1,994,198)
Repurchase of common stock under prepaid forward contract	(55,000)	$ (2)				(54,998)
Capped call options associated with convertible notes	(46,004)		(46,004)
Net loss	$ (143,551)			(143,551)
Balance (in shares) at Dec. 31, 2020	27,910,366	25,916,168
Balance at Dec. 31, 2020	$ (96,134)	$ 26	$ 797,655	$ (838,817)	$ 0	$ (54,998)

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net loss	$ (143,551)	$ (97,165)	$ (201,810)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	547	319	265
Accretion of premiums and discounts on investments	(97)	(200)	(217)
Amortization of discount and issuance costs on convertible notes	1,741	0	0
Acquired in-process research and development (Note 3)	12,500	0	0
Non-cash interest expense related to the revenue interest liability	19,560	8,120	0
Stock-based compensation expense	28,385	25,884	23,968
Changes in assets and liabilities:
Prepaids and other assets	(14,793)	(3,396)	(2,884)
Deferred revenue	(490)	2,152	0
Inventories	(16,136)	0	0
Other long-term liabilities	1,290	0	0
Accounts payable	23,106	(16,055)	24,446
Other accrued liabilities	2,761	10,000	7,594
Net cash used in operating activities	(85,177)	(70,341)	(148,638)
Investing activities
Purchases of investments	(4,420)	(34,326)	(25,481)
Purchases of in-process research and development	(12,500)	0	0
Proceeds from sales/maturities of investments	39,145	99,510	166,081
Purchase of property and equipment	(869)	(953)	(151)
Net cash provided by investing activities	21,356	64,231	140,449
Financing activities
Proceeds from issuance of convertible notes	280,000	0	0
Payment for debt issuance costs	(8,405)	0	0
Prepayment of forward stock repurchase transaction	(55,000)	0	0
Purchase of capped call options associated with convertible notes	(46,004)	0	0
Proceeds from revenue interest liability, net of issuance costs	25,000	124,424	0
Payments on revenue interest liability	(500)	0	0
Proceeds from exercise of common stock options	6,634	11,771	11,743
Payments on long-term debt	0	0	(1,049)
Net cash provided by financing activities	201,725	136,195	10,694
Net increase in cash, cash equivalents and restricted cash	137,904	130,085	2,505
Cash and cash equivalents at beginning of period	167,058	36,973	34,468
Cash, cash equivalents and restricted cash at end of period	304,962	167,058	36,973
Supplemental disclosure of cash flow information:
Purchase of property and equipment not yet paid	0	190	199
Non cash right of use asset	20	31	0
Offering costs not yet paid	$ 495	$ 0	$ 0

The Company and Basis of Presentation	12 Months Ended
The Company and Basis of Presentation	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company and Basis of Presentation	The Company and Basis of Presentation Esperion Therapeutics, Inc. ("the Company”) is the Lipid Management Company, a pharmaceutical company singularly focused on developing and commercializing affordable, oral, once-daily, non-statin medicines for the treatment of patients struggling with elevated low density lipoprotein cholesterol ("LDL-C"). The Esperion team of lipid experts are dedicated to lowering bad cholesterol through the discovery, development and commercialization of innovative medicines and their combinations with established medicines. The Company's first two products were approved by the U.S. Food and Drug Administration ("FDA"), European Medicines Agency ("EMA") and Swiss Agency for Therapeutic Products ("Swissmedic") in 2020. Bempedoic acid and the bempedoic acid / ezetimibe combination tablets are oral, once-daily, non-statin, LDL-C lowering medicines for patients with atherosclerotic cardiovascular disease ("ASCVD") or heterozygous familial hypercholesterolemia ("HeFH"). On February 21, 2020, the Company announced that the FDA approved NEXLETOL® as an adjunct to diet and maximally tolerated statin therapy for the treatment of adults with HeFH or established ASCVD who require additional lowering of LDL-C. The effect of NEXLETOL on cardiovascular morbidity and mortality has not been determined. NEXLETOL is the first oral, once-daily, non-statin LDL-C lowering medicine approved since 2002 for indicated patients. NEXLETOL became commercially available in the U.S. on March 30, 2020. On February 26, 2020, the Company announced that the FDA approved NEXLIZET® as an adjunct to diet and maximally tolerated statin therapy for the treatment of adults with HeFH or established ASCVD who require additional lowering of LDL-C. The effect of NEXLIZET on cardiovascular morbidity and mortality has not been determined. NEXLIZET is the first non-statin, LDL-C lowering fixed combination drug product ever approved. NEXLIZET became commercially available in the U.S. on June 4, 2020. On April 6, 2020, the Company announced that the European Commission (“EC”) approved the NILEMDO™ (bempedoic acid) and NUSTENDI™ (bempedoic acid and ezetimibe) tablets for the treatment of hypercholesterolemia and mixed dyslipidemia. The decision is applicable to all 27 European Union member states plus the United Kingdom (until December 31, 2020), Iceland, Norway and Liechtenstein. NILEMDO (bempedoic acid) and NUSTENDI (bempedoic acid and ezetimibe) are the branded products names for bempedoic acid and the bempedoic acid / ezetimibe combination tablets in Europe. NILEMDO is the first, oral, non-statin, LDL-C lowering medicine approved in Europe in almost two decades for indicated patients, and NUSTENDI is the first non-statin, LDL-C lowering combination medicine ever approved in Europe. In November 2020, the Company announced the commercial launch of NILEMDO and NUSTENDI in Germany. In December 2020, the Company announced the approval of NILEMDO and NUSTENDI in Switzerland. With respect to the United Kingdom, on January 1, 2021 all existing centralized marketing authorizations (which applied to our marketing authorizations for NILEMDO and NUSTENDI) were automatically converted to Great Britain marketing authorizations (under the Northern Ireland Protocol, centralized marketing authorizations remain valid for marketing products in Northern Ireland). On April 17, 2020, the Company entered into a license and collaboration agreement (the "Otsuka Agreement") with Otsuka Pharmaceutical Co., Ltd. ("Otsuka"). Pursuant to the Otsuka Agreement, the Company granted Otsuka exclusive development and commercialization rights to NEXLETOL and NEXLIZET in Japan. Otsuka will be responsible for all development, regulatory, and commercialization activities in Japan (the "Otsuka Territory"). In addition, Otsuka will fund all clinical development costs associated with the program in Japan. The Company received an upfront cash payment of $60 million in April 2020 and will receive up to an additional $450 million in total development and sales milestones. The Company will also receive tiered royalties ranging from 15 percent to 30 percent on net sales in Japan. In 2019 the Company entered into a license and collaboration agreement ("LCA Agreement") with Daiichi Sankyo Europe GmbH ("DSE"). Pursuant to the agreement, the Company granted DSE exclusive commercialization rights to bempedoic acid and the bempedoic acid / ezetimibe combination tablet in the European Economic Area and Switzerland (the "DSE Territory"). DSE will be responsible for commercialization in the DSE Territory. The Company remains responsible for clinical development, regulatory and manufacturing activities for the licensed products globally, including in the DSE Territory. On June 18, 2020, the Company entered into an amendment to the license and collaboration agreement ("LCA Amendment") with DSE dated as of January 2, 2019. In June 2020, the Company completed the transfer of the Marketing Authorisation Applications ("MAAs") for NILEMDO and NUSTENDI. Pursuant to the terms of the amendment, DSE paid the Company the second $150 million milestone based on completion of the NUSTENDI MAA transfer rather than the first product sale in the EU. Prior to the execution of the LCA Amendment, the milestone payment was due upon the first commercial sale in Europe. Additionally, the Company and DSE have agreed to expand the territory in which DSE has exclusive commercialization rights to NILEMDO and NUSTENDI to include Turkey. DSE's designated affiliate in Turkey will be solely responsible, at its sole cost and expense, for all regulatory matters relating to such products in Turkey, including obtaining Regulatory Approval for such product in Turkey. The Company's primary activities since incorporation have been conducting research and development activities, including nonclinical, preclinical and clinical testing, performing business and financial planning, recruiting personnel, and raising capital. The Company received approval by the FDA in February 2020 to commercialize NEXLETOL and NEXLIZET in the U.S., and accordingly commenced principal operations on March 30, 2020 with the commercialization of NEXLETOL. The Company is subject to risks and uncertainties which include the need to successfully commercialize its products, research, develop, and clinically test therapeutic products; obtain regulatory approvals for its products; expand its management, commercial and scientific staff; and finance its operations with an ultimate goal of achieving profitable operations. The Company has sustained annual operating losses since inception and expects such losses to continue over the foreseeable future. While management believes current cash resources and future cash received from the Company's net product sales, collaboration agreements with DSE and Otsuka, entered into on January 2, 2019 and April 17, 2020, respectively, and from the Revenue Interest Purchase Agreement (“RIPA”) with Eiger III SA LLC (“Oberland”), an affiliate of Oberland Capital LLC, and the Purchasers named therein, entered into on June 26, 2019, will fund operations for the foreseeable future, management may continue to fund operations and advance the development of the Company's products and product candidates through a combination of collaborations with third parties, strategic alliances, licensing arrangements, permitted debt financings, permitted royalty-based financings, and permitted private and public equity offerings or through other sources. The impact of COVID-19 and the uncertainty around the global pandemic could further impact the commercial launch of NEXLETOL and NEXLIZET and the Company’s research and development programs and could result in lower cash flows or higher costs that could further impact the Company’s overall operations and cash needs in the future. If adequate funds are not available, the Company may not be able to continue the development of its current products or future product candidates, or to commercialize its current or future product candidates, if approved. Basis of Presentation The accompanying financial statements have been prepared by the Company in accordance with generally accepted accounting principles in the United States of America (“GAAP”).

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in accordance with generally accepted accounting principles in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, net revenues, expenses and related disclosures. Actual results could differ from those estimates. Cash and Cash Equivalents The Company invests its excess cash in bank deposits, money market accounts, and short-term investments. The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash equivalents are reported at fair value. Restricted Cash Restricted cash consists of legally restricted amounts held by financial institutions pursuant to contractual arrangements. Investments Investments are considered to be available-for-sale and are carried at fair value. Unrealized gains and losses, if any, are reported as a separate component of stockholders’ equity. The cost of investments classified as available-for-sale are adjusted for the amortization of premiums and accretion of discounts to maturity and recorded in other income, net. Realized gains and losses, if any, are determined using the specific identification method and recorded in other income, net. Investments with original maturities beyond 90 days at the date of purchase and which mature at, or less than twelve months from, the balance sheet date are classified as current. Investments with a maturity beyond twelve months from the balance sheet date are classified as long-term. Selling, General and Administrative Expenses Selling, general and administrative expenses primarily consist of salaries and benefits, stock-based compensation, and costs of programs necessary for the general conduct of the Company's business, including costs associated with the commercialization of NEXLETOL and NEXLIZET in the U.S. Selling, general and administrative expenses are expensed as costs are incurred, services are performed, or goods are delivered. The Company incurred advertising costs of $19.3 million for the year ended December 31, 2020. Concentration of Credit Risk Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to concentrations of credit risk. The Company has established guidelines for investment of its excess cash and believes the guidelines maintain safety and liquidity through diversification of counterparties and maturities. The Company enters into a limited number of distribution agreements with distributors and specialty pharmacies. The Company's net product sales are with these customers. As of December 31, 2020, eight customers accounted for all of the Company's net trade receivables. Inventories Inventories are stated at the lower of cost or net realizable value and recognized on a first-in, first-out ("FIFO") method. The Company uses standard cost to determine the cost basis for inventory. Inventory is capitalized based on when future economic benefit is expected to be realized. The Company began capitalizing inventory upon receiving FDA approval for NEXLETOL and NEXLIZET on February 21, 2020 and February 26, 2020, respectively. Prior to the FDA approval of NEXLETOL and NEXLIZET, expenses associated with the manufacturing of the Company's products were recorded as research and development expense. The Company analyzes its inventory levels on a periodic basis to determine if any inventory is at risk for expiration prior to sale or has a cost basis that is greater than its estimated future net realizable value. Any adjustments are recognized through cost of goods sold in the period in which they are incurred. Segment Information The Company views its operations and manages its business in one operating segment, which is the business of researching, developing and commercializing therapies for the treatment of patients with elevated LDL-C. Fair Value of Financial Instruments The Company’s cash, cash equivalents, restricted cash and investments are carried at fair value. Financial instruments, including other prepaid and current assets, accounts payable and accrued liabilities are carried at cost, which approximates fair value. Debt is carried at amortized cost, which approximates fair value. Property and Equipment, Net Property and equipment are recorded at cost, less accumulated depreciation. Depreciation is provided using the straight-line method over the estimated useful lives of the respective assets, generally three to ten years. Leasehold improvements are amortized over the lesser of the lease term or the estimated useful lives of the related assets. Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. The impairment loss, if recognized, would be based on the excess of the carrying value of the impaired asset over its respective fair value. No impairment losses have been recorded through December 31, 2020. Leases The Company reviews all arrangements to determine if the contract contains a lease or an embedded lease using the criteria in Accounting Standards Codification ("ASC") 842 Leases ("ASC 842"). If a lease is identified, the Company reviews the consideration in the contract and separates the lease components from the nonlease components. In addition, the Company reviews the classification of the lease between operating and finance leases. According to ASC 842, lessees should discount lease payments at the lease commencement date using the rate implicit in the lease. If the rate implicit in the lease is not readily determinable, a lessee must use its incremental borrowing rate for purposes of classifying the lease and measuring the right-of-use asset and liability. To the extent the rate is not implicit in the lease, the Company uses the incremental borrowing rate it would have to pay to borrow on a collateralized basis over a similar term in an amount equal to the lease payments in a similar economic environment. Convertible Notes The Company accounts for convertible debt instruments that may be settled in cash or equity upon conversion by separating the liability and equity components of the instruments in a manner that reflects the nonconvertible debt borrowing rate. The Company determined the carrying amount of the liability component of the Convertible Notes by using estimates and assumptions that market participants would use in pricing a debt instrument. These estimates and assumptions are judgmental in nature and could have a significant impact on the determination of the debt component, and the associated non-cash interest expense. The equity component is treated as a discount on the liability component of the Convertible Notes, which is amortized over the term of the Convertible Notes using the effective interest rate method. Debt issuance costs related to the Convertible Notes are allocated to the liability and equity components of the Convertible Notes based on their relative values. Debt issuance costs allocated to the liability component are amortized over the life of the Convertible Notes as additional non-cash interest expense. Transaction costs allocated to equity are netted with the equity component of the convertible debt instrument in stockholders’ equity (deficit). Revenue Interest Liability The revenue interest liability is presented net of deferred issuance costs on the balance sheets. The Company imputes interest expense associated with this liability using the effective interest rate method. The effective interest rate is calculated based on the rate that would enable the debt to be repaid in full over the anticipated life of the arrangement. The interest rate on the liability may vary during the term of the agreement depending on a number of factors, including the level of forecasted net sales. The Company evaluates the interest rate quarterly based on its current net sales forecasts utilizing the prospective method. Revenue Recognition In accordance with ASC 606, Revenue from Contracts with Customers ("ASC 606"), the Company recognizes revenue when a customer obtains control of promised goods or services, in an amount that reflects the consideration the Company expects to receive in exchange for the goods or services provided. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: identify the contracts with a customer; identify the performance obligations in the contract; determine the transaction price; allocate the transaction price to the performance obligations in the contract; and recognize revenue when or as the entity satisfies a performance obligation. At contract inception the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when or as the performance obligation is satisfied. The Company derives revenue through two primary sources: collaboration revenue and product sales. Collaboration revenue consists of the collaboration payments to the Company for collaboration arrangements outside of the United States for the development, manufacturing and commercialization of the Company's product candidates by the Company's partners and product sales consists of sales of NEXLETOL and NEXLIZET in the United States. a.Collaboration Revenue The Company has entered into agreements related to its activities to develop, manufacture, and commercialize its product candidates. The Company earns collaboration revenue in connection with a collaboration agreement to develop and/or commercialize product candidates where the Company deems the collaborator to be the customer. In accordance with ASC 606, revenue is measured as the amount of consideration expected to be entitled to in exchange for transferring promised goods or providing services to a customer. Revenue is recognized when (or as) the Company satisfies performance obligations under the terms of a contract. Depending on the terms of the arrangement, the Company may defer the recognition of all or a portion of the consideration received as the performance obligations are satisfied. The collaboration agreements may require the Company to deliver various rights, services, and/or goods across the entire life cycle of a product or product candidate. In an agreement involving multiple goods or services promised to be transferred to a customer, the Company must assess, at the inception of the contract, whether each promise represents a separate performance obligation (i.e., is "distinct"), or whether such promises should be combined as a single performance obligation. The terms of the agreements typically include consideration to be provided to the Company in the form of non-refundable up-front payments, development milestones, sales milestones, and royalties on sales of products within a respective territory. The Company recognizes regulatory and approval milestones consideration when it is probable that a future reversal is unlikely to occur. For sales based milestones and royalties based on sales of product in a territory, the Company applies the sales-based royalty exception in ASC 606 to all of these milestones and royalties. At the inception of a contract, the transaction price reflects the amount of consideration the Company expects to be entitled to in exchange for transferring promised goods or services to its customer. In the arrangement where the Company satisfies performance obligation(s) during the regulatory phase over time, the Company recognizes collaboration revenue typically using an input method on the basis of regulatory costs incurred relative to the total expected cost which determines the extent of progress toward completion. The Company reviews the estimate of the transaction price and the total expected cost each period, and makes revisions to such estimates as necessary. Under contracted supply agreements with collaborators, the Company may manufacture and supply quantities of active pharmaceutical ingredient (“API”) or bulk tablets reasonably required by collaboration partners for the development or sale of licensed products in their respective territory. The Company recognizes revenue when the collaboration partner has obtained control of the API or bulk tablets. The Company records the costs related to the supply agreement in cost of goods sold on the statements of operations and comprehensive income (loss). Under the Company's collaboration agreements, product sales and cost of sales may be recorded by the Company's collaborators as they are deemed to be the principal in the transaction. The Company receives royalties from the commercialization of such products, and records its share of the variable consideration, representing a percentage of net product sales, as collaboration revenue in the period in which such underlying sales occur and costs are incurred by the collaborators. The collaborators will provide the Company with estimates of its royalties for such quarter; these estimates are reconciled to actual results in the subsequent quarter, and the royalty is adjusted accordingly, as necessary. Please refer to the discussion in Note 3 "Collaborations with Third Parties" for further discussion of the accounting related to the collaboration agreements. b.Product Sales, Net On March 30, 2020, NEXLETOL was commercially available in the U.S. through prescription and on June 4, 2020, NEXLIZET was commercially available in the U.S. through prescription. Net product sales totaled $13.0 million for the year ended December 31, 2020. The Company sells NEXLETOL and NEXLIZET to wholesalers in the U.S and recognizes revenue at the point in time when the customer is deemed to have obtained control of the product. The customer is deemed to have obtained control of the product at the time of physical receipt of the product at the customers’ distribution facilities, or free on board (“FOB”) destination, the terms of which are designated in the contract. Product sales are recorded at the net selling price, which includes estimates of variable consideration for which reserves are established for (a) rebates and chargebacks, (b) co-pay assistance programs, (c) distribution fees, (d) product returns, and (e) other discounts and fees. Where appropriate, these estimates take into consideration a range of possible outcomes which are probability-weighted for relevant factors such as current contractual and statutory requirements, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company's best estimates of the amount of consideration to which it is entitled based on the terms of the applicable contract. The amount of variable consideration may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Given the early stage of the Company’s commercial operations it has provided constraint of its variable consideration due to its potential consumption trends. Actual amounts of consideration ultimately received may differ from the Company's estimates. If actual results in the future vary from estimates, the Company adjusts these estimates, which would affect net product revenue and earnings in the period such variances become known. Liabilities for co-pay assistance, expected product returns, rebates, and distributor fees are classified as “Other accrued liabilities” in the balance sheets. Discounts, such as prompt pay discounts, and chargebacks are recorded as a reduction to trade accounts receivable, which is included in “Other prepaid and current assets” in the balance sheets. Forms of Variable Consideration Rebates and Chargebacks: The Company estimates reductions to product sales for Public Health Service Institutions, such as Medicaid, Medicare and Veterans' Administration ("VA") programs, as well as certain other qualifying federal and state government programs, and other group purchasing organizations. The Company estimates these reductions based upon the Company's contracts with government agencies and other organizations, statutorily defined discounts and estimated payor mix. These organizations purchase directly from the Company's wholesalers at a discount and the wholesalers charge the Company back the difference between the wholesaler price and the discounted price. The Company's liability for Medicare and Medicaid rebates consists of estimates for claims that a state will make for a current quarter. The Company's reserve for this discounted pricing is based on expected sales to qualified healthcare providers and the chargebacks that customers have already claimed. Co-pay assistance: Eligible patients who have commercial insurance may receive assistance from the Company to reduce the patient's out of pocket costs. The Company will buy down the difference between the amount of the eligible patient's co-pay when the drug is purchased at the pharmacy at a determined price. Liabilities for co-pay assistance are calculated by actual program participation from third-party administrators. Distribution Fees: The Company has written contracts with its customers that include terms for distribution fees and costs for inventory management. The Company estimates and records distribution fees due to its customers based on gross sales. Product Returns: The Company generally offers a right of return based on the product’s expiration date and certain spoilage and damaged instances. The Company estimates the amount of product sales that may be returned and records the estimate as a reduction of product sales in the period the related product sales is recognized. The Company’s estimates for expected returns are based primarily on an ongoing analysis of sales information and visibility into the inventory remaining in the distribution channel. Discounts: The Company provides product discounts, such as prompt pay discounts, to its customers. The Company estimates cash discounts based on terms in negotiated contracts and the Company’s expectations regarding future payment patterns. Cost of Goods Sold Cost of goods sold is related to the Company's net product sales of NEXLETOL and NEXLIZET and the cost of the API supplied to collaboration partners from supply agreements. Cost of goods sold includes the actual product costs, including inbound freight charges and certain outbound freight charges, purchasing, sourcing, inspection and receiving costs. Research and Development Research and development expenses consist of costs incurred to further the Company’s research and development activities and include salaries and related benefits, costs associated with clinical activities, nonclinical activities, regulatory activities, manufacturing activities to support clinical activities and commercial product manufacturing supply prior to the Company's regulatory approval, research-related overhead expenses, in-licensing agreements and fees paid to external service providers that conduct certain research and development, clinical, and manufacturing activities on behalf of the Company. Research and development costs are expensed as incurred. In accordance with ASC 730, Research and Development, costs incurred in obtaining in-licenses are charged to research and development expense if the in-licensed technology has not reached commercial feasibility and has no alternative future use. Such licenses purchased by the Company require substantial completion of research and development, regulatory and marketing approval efforts in order to reach commercial feasibility and has no alternative future use. Accrued Clinical Development Costs Outside research costs are a component of research and development expense. These expenses include fees paid to clinical research organizations and other service providers that conduct certain clinical and product development activities on behalf of the Company. Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly. Income Taxes Deferred tax assets and liabilities are determined based on differences between financial reporting and the tax basis of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company has incurred annual operating losses since inception. Accordingly, it is not more likely than not that the Company will realize a tax benefit from its deferred tax assets and as such, it has recorded a full valuation allowance. Stock-Based Compensation The Company accounts for stock-based compensation in accordance with the provisions of ASC 718, Compensation—Stock Compensation. Accordingly, compensation costs related to equity instruments granted are recognized over the requisite service periods of the awards on a straight-line basis at the grant-date fair value calculated using a Black-Scholes option-pricing model. The Company accounts for forfeitures as they occur. Expense is recognized during the period the related services are rendered. Recent Accounting Pronouncements In June 2016, the FASB issued Accounting Standard Update ("ASU") 2016-13, Financial Instruments—Credit Losses (Topic 326), which requires financial instruments to be recognized at an estimate of current expected credit losses. As part of the ASU, financial assets measured at amortized cost will be presented at the net amount expected to be collected. In addition, companies will recognize an allowance for credit losses on available-for-sale investments rather than reducing the amortized cost in an other-than-temporary impairment. The standard is effective for public companies for fiscal years beginning after December 15, 2019, and interim periods within those years. The Company has chosen the practical expedient to exclude accrued interest from both the fair value and the amortized cost basis of available-for-sale debt securities in identifying and measuring an impairment. The Company adopted the standard effective January 1, 2020. The adoption of this standard did not have a material impact on the Company’s balance sheets, statements of operations or statements of cash flows. In August 2018, the FASB issued ASU 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which includes provisions to clarify customer’s accounting for implementation costs incurred in a cloud computing arrangement. Under the updated guidance, a customer in a cloud computing arrangement that is a service contract should follow the internal-use software guidance to determine how to account for costs incurred in implementation. The updated guidance also requires certain classification on the balance sheets, statements of operations and statements of cash flows as well as additional quantitative and qualitative disclosures. The standard is effective for public companies for fiscal years beginning after December 15, 2019, and interim periods within those years. Entities can choose to adopt the new guidance prospectively or retrospectively. The Company adopted the standard effective January 1, 2020, and has chosen to adopt the standard prospectively. Implementation costs for cloud computing arrangements are capitalized in "Other prepaid and current assets" on the Company's balance sheets. The adoption of this standard did not have a material impact to the Company’s balance sheets, statements of operations or statements of cash flows. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, as part of its initiative to reduce complexity in accounting standards. The amendments in this update simplify the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. The amendments within ASU 2019-12 are effective for financial statements issued for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, and early adoption is permitted. The Company early adopted this standard for the year ended December 31, 2020, which amended the existing standards for income tax accounting, eliminating the legacy exception on how to allocate income tax expense or benefit for the year to continuing operations, discontinued operations, other comprehensive income, and other charges or credits recorded directly to shareholder’s equity. We did not adjust comparative periods in our financial statements prior to that period. Adoption of the new standard on January 1, 2020 resulted in determining the tax effect of income or loss from continuing operations using a computation that does not consider the tax effects of items that are not included in continuing operations. As such, the Company did not record a tax expense or benefit related to amounts credited directly to shareholder equity. Refer to Note 16 for additional information. In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”). This ASU simplifies the accounting for convertible instruments by removing the separation models for convertible debt with cash conversion features and convertible instruments with a beneficial conversion feature, which requires the fair value of the embedded conversion feature of convertible instruments be allocated to equity. Under ASU 2020-06, a convertible debt instrument with those features will generally be reported as a single liability at its amortized cost with no separate accounting for the embedded conversion features in equity. The adoption of this ASU will result in the reclassification of the portion of the Company's convertible notes from equity to debt, which will also reduce reported interest expense and increase reported net income. ASU 2020-06 requires the application of the if-converted method when calculating diluted earnings per share, eliminating the Company’s ability to use the treasury stock method when certain conditions are met. The ASU is effective for annual reporting periods beginning after December 15, 2021, with early adoption permitted no earlier than fiscal years beginning after December 15, 2020. The Company plans to early adopt this standard as of January 1, 2021 which will result in a net increase in the Convertible notes of approximately $92.0 million, an adjustment to accumulated deficit of approximately $1.5 million, and a reduction to additional paid-in capital of $93.5 million. The Company does not expect any tax impact of the adoption to be material.

Collaborations with Third Parties	12 Months Ended
Collaborations with Third Parties	Dec. 31, 2020
Collaborations with Third Parties
Collaborations with Third Parties	Collaborations with Third Parties DSE Agreement Terms On January 2, 2019, the Company entered into a license and collaboration agreement with DSE. Pursuant to the agreement, the Company granted DSE exclusive commercialization rights to bempedoic acid and the bempedoic acid / ezetimibe combination tablet in the European Economic Area and Switzerland (“DSE Territory”). DSE will be responsible for commercialization in the DSE Territory. The Company remains responsible for clinical development, regulatory and manufacturing activities for the licensed products globally, including in the DSE Territory. Pursuant to the agreement, the consideration consists of a $150.0 million upfront cash payment as well as $150.0 million cash payment to the Company upon first commercial sales in the DSE Territory. The Company also is responsible for supplying DSE with certain manufacturing supply of the API or bulk tablets. The Company is also eligible to receive a substantial additional regulatory milestone payment upon the grant of the marketing authorisation in the European Union for the CV risk reduction label, depending on the range of relative risk reduction in the CLEAR Outcomes study. In addition, the Company is eligible to receive additional sales milestone payments related to total net sales achievements for DSE in the DSE Territory. Finally, the Company will receive tiered fifteen percent (15%) to twenty-five percent (25%) royalties on net DSE Territory sales. The agreement calls for both parties to participate in a Joint Collaboration Committee (the “DSE JCC”). The DSE JCC is comprised of executive management from each company and the Company will lead in all aspects related to development and DSE will lead in all aspects related to commercialization in the DSE Territory. Agreement Terms Amendment On June 18, 2020, the Company entered into an amendment to the license and collaboration agreement with DSE, dated as of January 2, 2019. In June, the Company completed the transfer of the MAAs for NILEMDO and NUSTENDI. Pursuant to the terms of the amendment, DSE paid the Company the second $150.0 million milestone based on completion of the NUSTENDI MAA transfer rather than the first product sale in the EU, as previously agreed. Additionally, the Company and DSE have agreed to expand the DSE Territory, or the territory in which DSE has exclusive commercialization rights to NILEMDO and NUSTENDI to include Turkey. DSE's designated affiliate in Turkey will be solely responsible, at its sole cost and expense, for all regulatory matters relating to such products in Turkey, including obtaining regulatory approval for such products in Turkey. Collaboration Revenue The Company considered the guidance under ASC 606 and concluded that the agreement was in the scope of ASC 606. The Company concluded that the upfront payment of $150.0 million should be included in the transaction price and related to the following performance obligations under the agreement: 1) the license to the Company’s intellectual property and 2) the obligation to provide ongoing regulatory and development activities. The Company used the adjusted market assessment approach in determining the standalone selling price of the Company’s intellectual property and the expected cost plus margin approach in determining the standalone selling price of the Company’s obligation to provide ongoing regulatory and development activities. Accordingly, during the year ended December 31, 2019, the Company recognized $148.4 million of collaboration revenue related to the $150.0 million upfront payment, respectively. The $148.4 million related to the performance obligations for the license to the Company’s intellectual property and a portion of ongoing regulatory and development activities conducted during the period ended December 31, 2019, in the amounts of $144.4 million and $4.0 million, respectively. The remaining $1.6 million of the upfront payment was deferred as of December 31, 2019 due to an on-going performance obligation related to the ongoing regulatory efforts related to the MAA in the DSE Territory. During the year ended December 31, 2020, the Company recognized $1.6 million related to the on-going performance obligation for the ongoing regulatory efforts related to the MAA in the DSE Territory, which was transferred to DSE in June 2020. In addition, in the year ended December 31, 2020, the Company recognized the $150.0 million milestone as collaboration revenue based on the successful transfer of the NUSTENDI MAA. During the year ended December 31, 2020, the Company recognized collaboration revenue of $2.8 million related to royalty revenue and the sales of bulk tablets of NILEMDO and NUSTENDI to DSE pursuant to the Supply Agreement that was executed with DSE. All remaining future potential milestone amounts were not included in the transaction price, as they were all determined to be fully constrained following the concepts of ASC 606 due to the fact that such amounts hinge on development activities, regulatory approvals and sales-based milestones. Additionally, the Company expects that any consideration related to sales-based milestones will be recognized when the subsequent sales-based milestones are achieved. Otsuka Agreement Terms On April 17, 2020, the Company entered into the Otsuka Agreement. Pursuant to the Otsuka Agreement, the Company granted Otsuka exclusive development and commercialization rights to NEXLETOL and NEXLIZET in Japan. Otsuka will be responsible for all development, regulatory, and commercialization activities in Japan. In addition, Otsuka will fund all clinical development costs associated with the program in Japan. Pursuant to the agreement, the consideration consists of a $60.0 million upfront cash payment and the Company will be eligible to receive additional payments of up to $450.0 million if certain regulatory and commercial milestones are achieved by Otsuka. The potential future milestone payments include up to $20.0 million upon first JNDA submissions in the Otsuka Territory, up to $70.0 million upon the first NHI Price Listing for NEXLETOL in the Otsuka Territory, and up to $50.0 million upon the achievement of the primary major adverse cardiovascular events (“MACE”) in the CLEAR Outcomes study and the CV risk reduction rate on the U.S. label, depending on the range of relative risk reduction in the CLEAR Outcomes study. In addition, the Company is eligible to receive additional sales milestone payments up to $310.0 million related to total net sales achievements for Otsuka in Japan. Finally, the Company will receive tiered fifteen percent (15%) to thirty percent (30%) royalties on net sales in Japan. The agreement calls for both parties to participate in a Joint Collaboration Committee (the "Otsuka JCC"). The Otsuka JCC is comprised of executive management from each company and Otsuka will lead in all aspects related to development and commercialization in the Otsuka Territory. Collaboration Revenue The Company considered the guidance under ASC 606 and concluded that the agreement was in the scope of ASC 606. The Company concluded that the upfront payment of $60.0 million should be included in the transaction price and related to the performance obligation under the agreement to the license to the Company's intellectual property. During the year ended December 31, 2020, the Company recognized $60.0 million of collaboration revenue related to the $60.0 million upfront payment. All future potential milestone amounts were not included in the transaction price, as they were all determined to be fully constrained following the concepts of ASC 606 due to the fact that such amounts hinge on development activities, regulatory approvals and sales-based milestones. Additionally, the Company expects that any consideration related to royalties and sales-based milestones will be recognized when the subsequent sales occur. The Company has not yet recognized any revenue for milestone payments as the related regulatory and commercial milestones have not yet been achieved. Other Agreements During December 2020, the Company entered into a licensing agreement with Serometrix to in-license a series of early stage compounds known as scaffolds related to its oral, small molecule PCSK9 inhibitor program. PCSK9 is an enzyme responsible for regulating LDL receptors. PCSK9 inhibitors stop LDL receptors from being broken down, increasing the number of LDL receptors present to remove cholesterol from the blood. The agreement allows the Company use of the PCSK9 compounds, which were patented by Serometrix prior to the licensing agreement, to perform further research and development with the goal of developing a small molecule oral PCSK9 inhibitor that can be taken as a tablet. In exchange for these rights, the Company agreed to pay Serometrix an upfront payment, milestone payments and royalties on net sales of licensed products under the agreement. The Company is obligated to make milestone payments to Serometrix upon the achievement of specified development, regulatory and commercialization milestones. The development milestone payments due under the agreement depend on the licensed product being developed. As part of the agreement, the Company made an upfront cash payment of $12.5 million in December 2020, which was recorded to research and development expense, to Serometrix, with payments in future years tied to specific milestones. The Company has also agreed to pay tiered royalties based on net sales of all products licensed under the agreement of mid-single-digit to low double-digit percentages.

Inventories

12 Months Ended

Dec. 31, 2020

Inventory Disclosure [Abstract]

Inventories

Inventories consist of the following:


	December 31,
	2020		2019
	(in thousands)
Raw materials	$	13,788	—
Work in process	2,028		—
Finished goods	320		—
	$	16,136	$	—

Warrants	12 Months Ended
Warrants	Dec. 31, 2020
Warrants and Rights Note Disclosure [Abstract]
Warrants	Warrants In June 2014, the Company entered into a loan and security agreement (the "Credit Facility") with Oxford Finance LLC which provided for borrowings of $5.0 million under the term loan (the "Term A Loan"). On June 30, 2014, the Company received proceeds of $5.0 million from the issuance of secured promissory notes under the Term A Loan, which were collateralized by substantially all of the Company's personal property, other than its intellectual property. The Term A Loan was fully repaid in July 2018. In connection with the Credit Facility entered into in June 2014, the Company issued a warrant to purchase 8,230 shares of common stock at an exercise price of $15.19. The warrant was recorded at fair value of $0.1 million to additional-paid-in-capital. During the year ended December 31, 2019, 8,230 warrants were net exercised for 5,813 shares of the Company's common stock. During the year ended December 31, 2018, 177,123 warrants were net exercised for 159,944 shares of the Company's common stock. As of December 31, 2020 and December 31, 2019, the Company had no warrants outstanding.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company has entered into a contract manufacturing agreement with a third party commercial manufacturing organization for the production of certain inventory supplies of NEXLETOL and NEXLIZET. The agreement has an initial term of three years and will renew automatically for successive periods of one year each unless terminated by either party. Under the agreement, the Company is obligated to purchase minimum order commitments on a rolling twelve-month period for the batches of inventory supplies produced. The Company estimates future minimum inventory purchase commitments of $19.1 million for 2021. Legal Proceedings On January 12, 2016, a purported stockholder of the Company filed a putative class action lawsuit in the United States District Court for the Eastern District of Michigan, against the Company and Tim Mayleben, captioned Kevin L. Dougherty v. Esperion Therapeutics, Inc., et al. (No. 16-cv-10089). The lawsuit alleges that the Company and Mr. Mayleben violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 and SEC Rule 10b-5 by allegedly failing to disclose in an August 17, 2015, public statement that the FDA would require a cardiovascular outcomes trial before approving the Company’s lead product candidate. The lawsuit seeks, among other things, compensatory damages in connection with an allegedly inflated stock price between August 18, 2015, and September 28, 2015, as well as attorneys’ fees and costs. On May 20, 2016, an amended complaint was filed in the lawsuit and on July 5, 2016, the Company filed a motion to dismiss the amended complaint. On December 27, 2016, the court granted the Company’s motion to dismiss with prejudice and entered judgment in the Company’s favor. On January 24, 2017, the plaintiffs in this lawsuit filed a motion to alter or amend the judgment. In May 2017, the court denied the plaintiff’s motion to alter or amend the judgment. In May 2017, the court denied the plaintiff’s motion to alter or amend the judgment. On June 19, 2017, the plaintiffs filed a notice of appeal to the Sixth Circuit Court of Appeals and on September 14, 2017, they filed their opening brief in support of the appeal. The appeal was fully briefed on December 7, 2017, and it was argued before the Sixth Circuit on March 15, 2018. On September 27, 2018, the Sixth Circuit issued an opinion in which it reversed the district court’s dismissal and remanded for further proceedings. On October 11, 2018, the Company filed a petition for rehearing en banc and, on October 23, 2018, the Sixth Circuit Court of Appeals directed plaintiffs to respond to that petition. On December 3, 2018, the Sixth Circuit denied the Company’s petition for en banc rehearing, and on December 11, 2018, the case was returned to the federal district court by mandate from the Sixth Circuit. On December 26, 2018, the Company filed an answer to the amended complaint, and on March 28, 2019, the Company filed its amended answer to the amended complaint. On September 15, 2020, the Company filed a motion for summary judgment, and the plaintiffs filed a motion for partial summary judgment, and on October 23, 2020, the parties filed oppositions to both motions for summary judgment. On November 20, 2020, the Company and plaintiffs filed replies in support of their respective motions. The Company is unable to predict the outcome of this matter and is unable to make a meaningful estimate of the amount or range of loss, if any, that could result from an unfavorable outcome.On December 15, 2016, a purported stockholder of the Company filed a derivative lawsuit in the Court of Chancery of the State of Delaware against Tim Mayleben, Roger Newton, Mary McGowan, Nicole Vitullo, Dov Goldstein, Daniel Janney, Antonio Gotto Jr., Mark McGovern, Gilbert Omenn, Scott Braunstein, and Patrick Enright. The Company is named as a nominal defendant. The lawsuit alleges that the defendants breached their fiduciary duties to the Company when they made or approved improper statements on August 17, 2015, regarding the Company’s lead product candidate’s path to FDA approval, and failed to ensure that reliable systems of internal controls were in place at the Company. On February 8, 2019, the Company and defendants filed a motion to dismiss the derivative lawsuit. On April 23, 2019, the plaintiff filed an opposition to the motion to dismiss the derivative lawsuit, and the Company filed a reply brief on May 15, 2019. On November 6, 2019, the court held a hearing on the motion to dismiss. On February 13, 2020, the court granted the motion to dismiss with prejudice and entered judgment in the Company’s favor. On March 16, 2020, the plaintiff filed a notice of appeal to the Supreme Court of Delaware. On June 1, 2020, the plaintiff filed his opening brief on appeal to the Supreme Court of Delaware. On July 1, 2020, the Company and the defendants filed an answering brief, and on July 16, 2020, the plaintiff filed a reply brief. On October 14, 2020, the Supreme Court of Delaware held oral arguments on the appeal. On October 29, 2020, the Supreme Court of Delaware issued an order affirming the judgment of the Court of Chancery.

Property and Equipment

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property and Equipment

Property and equipment consist of the following:


	December 31,
	2020		2019
	(in thousands)

Computer equipment	$	278	$	256
Software	1,100		615
Furniture, fixtures and other	1,170		908
Leasehold improvements	299		298
Assets in Progress	—		99
Subtotal	2,847		2,176
Less accumulated depreciation and amortization	1,571		1,031
Property and equipment, net	$	1,276	$	1,145

Depreciation expense was $0.5 million, $0.3 million, and $0.3 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Other Accrued Liabilities

12 Months Ended

Dec. 31, 2020

Payables and Accruals [Abstract]

Other Accrued Liabilities

Other accrued liabilities consist of the following:


	December 31,
	2020		2019
	(in thousands)
Accrued compensation	$	15,161	$	7,818
Accrued professional fees	3,183		3,842
Accrued other	6,446		211
Total other accrued liabilities	$	24,790	$	11,871

Investments

12 Months Ended

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Investments

The following table summarizes the Company’s cash equivalents and investments:


	December 31, 2020
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
	(in thousands)
Cash equivalents:
Money market funds	$	281,783	$	—	$	—	$	281,783






Total	$	281,783	$	—	$	—	$	281,783


	December 31, 2019
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
	(in thousands)
Cash equivalents:
Money market funds	$	20,970	$	—	$	—	$	20,970
U.S. treasury notes	2,497		—		—		2,497
Commercial paper	4,494		—		—		4,494
Short-term investments:
Certificates of deposit	245		—		—		245
U.S. treasury notes	29,155		23		—		29,178
Commercial paper	5,228		—		—		5,228
Total	$	62,589	$	23	$	—	$	62,612

At December 31, 2019, remaining contractual maturities of available-for-sale investments classified as current on the balance sheet were less than 12 months. The company does not intend to sell the investments before maturity.

During the years ended December 31, 2020, 2019 and 2018, other income, net in the statements of operations includes interest income on available-for-sale investments of $0.5 million, $3.7 million and $2.6 million, respectively. Other income, net in the statements of operations includes income for the accretion of premiums and discounts on investments of $0.1 million, $0.3 million and $0.2 million during the years ended December 31, 2020, 2019 and 2018, respectively.

There were no unrealized gains or losses on investments reclassified from accumulated other comprehensive loss to other income, net in the statements of operations during the year ended December 31, 2020.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

The Company follows accounting guidance that emphasizes that fair value is a market-based measurement, not an entity-specific measurement. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” Fair value measurements are defined on a three level hierarchy:


Level 1 inputs:						Quoted prices for identical assets or liabilities in active markets;

Level 2 inputs:						Observable inputs other than Level 1 prices, such as quoted market prices for similar assets or liabilities or other inputs that are observable or can be corroborated by market data; and

Level 3 inputs:						Unobservable inputs that are supported by little or no market activity and require the reporting entity to develop assumptions that market participants would use when pricing the asset or liability.

The following table presents the Company’s financial assets that have been measured at fair value on a recurring basis:


Description	Total		Level 1		Level 2		Level 3

December 31, 2020

Money market funds	$	281,783	$	281,783	$	—	$	—




Total assets at fair value	$	281,783	$	281,783	$	—	$	—
December 31, 2019

Money market funds	$	20,970	$	20,970	$	—	$	—
Investments:
Certificates of deposit	245		245		—		—
U.S. treasury notes	31,675		31,675		—		—
Commercial paper	9,722		—		9,722		—
Total assets at fair value	$	62,612	$	52,890	$	9,722	$	—

There were no transfers between Levels 1, 2 or 3 during the years ended December 31, 2020 or December 31, 2019.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Liability Related to the Revenue Interest Purchase Agreement

12 Months Ended

Dec. 31, 2020

On June 26, 2019, the Company entered into a RIPA with Oberland, as agent for purchasers party thereto (the “Purchasers”), and the Purchasers named therein, to obtain financing in respect to the commercialization and further development of bempedoic acid and the bempedoic acid / ezetimibe combination tablet and other working capital needs. Pursuant to the RIPA, the Company received $125.0 million at closing, less certain issuance costs. The Company will also be entitled to receive up to approximately $75.0 million in subsequent installments subject to the terms and conditions set forth in the RIPA: (i) $25.0 million upon certain regulatory approval of its product candidates and (ii) $50.0 million, at the Company’s option, upon reaching $100.0 million trailing worldwide six-month net sales any time prior to December 31, 2021 (the “Third Payment”).

As consideration for such payments, the Purchasers will have a right to receive certain revenue interests (the “Revenue Interests”) from the Company based upon net sales of the Company’s certain products, once approved, which will be tiered payments initially ranging from 2.5% to 7.5% of the Company’s net sales in the covered territory (the “Covered Territory”); provided that (a) if annual net sales equal or exceed $350.0 million by December 31, 2021 (the “Sales Threshold”), the initially tiered revenue interest rate will be decreased to a single rate of 2.5% of the Company’s net sales in the Covered Territory, beginning on January 1, 2022, and (b) if annual net sales equal or exceed the Sales Threshold and if the Purchasers receive

100% of their invested capital by December 31, 2024, the revenue interest rate will be decreased to a single rate of 0.4% of the Company’s net sales in the Covered Territory beginning on January 1, 2025. If the Third Payment is drawn down by the Company, the applicable royalty rates will increase by one-third. The Covered Territory is the United States, but is subject to expand to include the world-wide net sales if the Company’s annual U.S. net sales are less than $350.0 million for the year ended December 31, 2021. The U.S. net sales milestone thresholds are not to be taken as financial guidance. The Purchasers’ rights to receive the Revenue Interests shall terminate on the date on which the Purchasers have received Revenue Interests payments of 195% of the then aggregate purchase price (the “Cumulative Purchaser Payments”) paid to the Company, unless the RIPA is terminated earlier.

Under the RIPA, the Company has an option (the “Call Option”) to terminate the RIPA and repurchase future Revenue Interests at any time upon advance written notice. Additionally, the Purchasers have an option (the “Put Option”) to terminate the RIPA and to require the Company to repurchase future Revenue Interests upon enumerated events such as a bankruptcy event, an uncured material breach, a material adverse effect or a change of control. If the Put Option is exercised prior to the first anniversary of the closing date by the Purchasers (except pursuant to a change of control), the required repurchase price will be 120% of the Cumulative Purchaser Payments (minus all payments Company has made to the Purchasers in connection with the Revenue Interests). In all other cases, if the Put Option or the Call Option are exercised, the required repurchase price will be 175% of the Cumulative Purchaser Payments (minus all payments Company has made to the Purchasers in connection with the Revenue Interests), if such option is exercised prior to the third anniversary of the closing date, and 195% of the Cumulative Purchaser Payments (minus all payments Company has made to the Purchasers in connection with the Revenue Interests), if such option is exercised thereafter.

In addition, the RIPA contains various representations and warranties, information rights, non-financial covenants, indemnification obligations and other provisions that are customary for a transaction of this nature.

In connection with the arrangement, as of December 31, 2020, the Company has recorded a liability, referred to as the “Revenue interest liability” on the balance sheets, of $176.6 million, net of $0.5 million of capitalized issuance costs in connection with the RIPA, which will be amortized to interest expense over the estimated term of the RIPA. The Company imputes interest expense associated with this liability using the effective interest rate method. The effective interest rate is calculated based on the rate that would enable the debt to be repaid in full over the anticipated life of the arrangement. The interest rate on this liability may vary during the term of the agreement depending on a number of factors, including the level of forecasted net sales. The Company evaluates the interest rate quarterly based on its current net sales forecasts utilizing the prospective method.

A significant increase or decrease in net sales will materially impact the revenue interest liability, interest expense and the time period for repayment. The Company recorded approximately $19.6 million and $8.1 million in interest expense related to this arrangement for the years ended December 31, 2020 and 2019, respectively.

The repayment of the RIPA to Oberland does not have a fixed repayment schedule, rather it will be completely repaid and extinguished when the Company has repaid 195% of the aggregate purchase price unless the RIPA is terminated earlier. Since there is not a fixed repayment schedule, the Company does not project its future repayments by year. Each period, the Company estimates the future expected sales of its products in the covered territory and determines the effective annual imputed interest rate, which updates and changes the timing of the Company’s payments. Under the terms of the agreement, every $100 million of net sales generated, less than or equal to $250 million in an annual aggregate year, would result in a repayment obligation of approximately $7.5 million or 7.5% at the stated repayment rate in the first year. Annual Net Sales for a calendar year exceeding $250 million would result in a repayment obligation of approximately $2.5 million or 2.5% for every $100 million of sales above the threshold. If the Company equals or exceeds $350 million of sales in the U.S. in 2021, then the repayment amount would drop to $2.5 million for every $100 million of net sales starting in 2022. If the U.S. net sales are less than $350 million for the year ended December 31, 2021, then the Covered Territory is expanded to include worldwide sales beginning in 2022. The Company’s repayments of the RIPA are directly tied to the growth of its net sales, and as the Company’s net sales grow, the Company expects the related repayments of the RIPA to grow as well. The Company currently expects to repay $5.4 million in the next twelve months.

The Company received $125.0 million in exchange for entering into the RIPA during June 2019 and $25.0 million in March 2020 upon receiving regulatory approval of NEXLETOL. The effective annual imputed interest rate was 10.6% as of

December 31, 2020. The Company incurred $0.6 million of issuance costs in connection with the RIPA, which will be amortized to interest expense over the estimated term of the RIPA. Payments made to Oberland as a result of the Company’s net sales will reduce the revenue interest liability.

The following table summarizes the revenue interest liability activity during the year ended December 31, 2020:


	(in thousands)
Revenue interest liability at December 31, 2019	$	132,544
Oberland funding for regulatory approval of NEXLETOL	25,000
Interest expense recognized	19,560
Revenue interest payments	(500)
Revenue interest liability at December 31, 2020	$	176,604

Convertible Notes

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Convertible Notes

On November 16, 2020, the Company issued $250.0 million aggregate principal amount of 4.0% senior subordinated convertible notes due November 15, 2025. The net proceeds the Company received from the offering of the initial notes was approximately $242.0 million, after deducting the initial purchasers’ discounts and commissions and offering expenses payable by the Company. In connection with the offering of the senior subordinated convertible notes, the Company granted the initial purchasers of the senior subordinated convertible notes a 30-day option to purchase up to an additional $30.0 million aggregate principal amount of the senior subordinated convertible notes on the same terms and conditions. On November 18, 2020 the option was exercised, which resulted in approximately $29.1 million of additional proceeds, for total aggregate principal of $280.0 million and net proceeds of $271.1 million (the additional notes and, together with the initial notes, collectively called the “Convertible Notes”). The Company used approximately $46.0 million of the net proceeds from the offering of the notes to pay the cost of the Capped Call (as defined below) and $55.0 million of the net proceeds from the offering of the initial notes to finance the Prepaid Forward (as defined below). The Convertible Notes are the Company's senior unsecured obligations and mature on November 15, 2025 (the “Maturity Date”), unless earlier repurchased or converted into shares of common stock under certain circumstances described below. The Convertible Notes are convertible into shares of the Company’s common stock, can be repurchased for cash, or a combination thereof, at the Company’s election, at an initial conversion rate of 30.2151 shares of common stock per $1,000 principal amount of the Convertible Notes, which is equivalent to an initial conversion price of approximately $33.096 per share of common stock, subject to adjustment. The Company will pay interest on the Convertible Notes semi-annually in arrears on May 15 and November 15 of each year.

The $271.1 million of proceeds received from the issuance of the Convertible Notes were allocated between long-term debt (the “liability component”) of $177.6 million and additional paid-in capital (the “equity component”) of $93.5 million. The fair value of the liability component was measured using rates determined for similar debt instruments without a conversion feature. The carrying amount of the equity component, representing the conversion option, was determined by deducting the fair value of the liability component from the aggregate face value of the Convertible Notes and is included in additional paid-in capital in the consolidated balance sheets and is not remeasured as long as it continues to meet the conditions for equity classification. The liability component will be accreted up to the face value of the Convertible Notes of $280.0 million, which will result in additional non-cash interest expense being recognized through the Maturity Date.

The Company incurred approximately $8.9 million of issuance costs related to the issuance of the Convertible Notes, of which $5.8 million and $3.1 million were allocated and recorded to long-term debt and additional paid-in capital, respectively. The $5.8 million of issuance costs recorded as long-term debt on the consolidated balance sheet are being amortized over the five-year contractual term of the Convertible Notes using the effective interest method. The effective interest rate on the Convertible Notes, including accretion of the Convertible Notes fair value to par and debt issuance cost amortization, is 14.55%.

The Convertible Notes are general unsecured obligations of the Company that are subordinated in right of payment to indebtedness, obligations and other liabilities under the Company’s RIPA, the revenue interests issued pursuant to such agreement, and any refinancing of the foregoing.

Holders may convert their Convertible Notes at their option at any time prior to the close of business on the business day immediately preceding August 15, 2025 in the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on March 31, 2021 (and only during such calendar quarter), if the last reported sale price per share of the Company’s common stock, par value $0.001 per share (“common stock”), is greater than or equal to 130% of the conversion price for each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter; (2) during the five business days after any five consecutive trading day period (such five consecutive trading day period, the “measurement period”) in which the trading price per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company’s common stock and the conversion rate for the notes on each such trading day; (3) if the Company calls such notes for redemption, any such notes that have been called for redemption may be converted at any time prior to the close of business on the second scheduled trading day immediately preceding the redemption date, but only with respect to the notes called for redemption; and (4) upon the occurrence of specified corporate events, as provided in the Indenture.

On or after August 15, 2025, to the close of business on the second scheduled trading day immediately before the maturity date, holders may convert all or any portion of their notes at the applicable conversion rate at any time at the option of the holder regardless of the foregoing conditions.

In addition, following certain corporate events or following issuance of a notice of redemption, the Company will, in certain circumstances, increase the conversion rate for a holder who elects to convert its notes in connection with such a corporate event or to convert its notes called (or deemed called) for redemption during the related redemption period, as the case may be.

The Convertible Notes will be redeemable, in whole or in part, at the Company’s option at any time, and from time to time, on or after November 20, 2023 and before the 41st scheduled trading day immediately before the maturity date, at a cash redemption price equal to 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest, if any, but only if the last reported sale price per share of the Company’s common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive), including the trading day immediately preceding the date the Company sends the related redemption notice, during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company sends such redemption notice. No sinking fund is provided for the notes. If the Company redeems less than all the outstanding notes, at least $125.0 million aggregate principal amount of notes must be outstanding and not subject to redemption as of the relevant redemption notice date.

If the Company undergoes a “fundamental change” (as defined in the Indenture), holders may require the Company to repurchase their notes for cash all or any portion of their notes at a fundamental change repurchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest, to, but excluding, the fundamental change repurchase date. The Indenture includes customary terms and covenants, including certain events of default.

The Convertible Notes consist of the following at December 31, 2020 (in thousands):


Principal amounts:
	Principal	$	280,000
	Unamortized debt discount	(94,900)
	Unamortized debt issuance cost	(5,733)
	Net carrying amount of the debt component	$	179,367

The Company recorded $3.1 million of interest expense during the year ended December 31, 2020, relating to the cash interest on the convertible notes due semi-annually, amortization of the debt discount and amortization of the debt issuance costs.

As of December 31, 2020, no Convertible Notes were convertible pursuant to their terms. The estimated fair value of the Convertible Notes was $283.4 million as of December 31, 2020. The estimated fair value of the Convertible Notes was determined through consideration of quoted market prices. As of December 31, 2020, the if-converted value of the Convertible Notes did not exceed the principal value of those notes.

Capped Call Transactions

In connection with the offering of the Convertible Notes, the Company entered into privately-negotiated capped call transactions with one of the initial purchasers of the convertible notes or its affiliate and certain other financial institutions. The Company used approximately $46.0 million of the net proceeds from the offering of the Convertible Notes to pay the cost of the capped call transactions. The capped call transactions are expected generally to reduce potential dilution to the Company’s common stock upon any conversion of the Convertible Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted notes, as the case may be, in the event that the market value per share of the Company’s common stock, as measured under the terms of the capped call transactions at the time of exercise, is greater than the strike price of the capped call transactions (which initially corresponds to the initial conversion price of the Convertible Notes, and is subject to certain adjustments), with such reduction and/or offset subject to a cap initially equal to approximately $55.16 (which represents a premium of approximately 100% over the last reported sale price of the Company’s common stock on November 11, 2020), subject to certain adjustments. The capped call transactions are separate transactions, entered into by the Company and are not part of the terms of the Convertible Notes.

Given that the transactions meet certain accounting criteria, the convertible note capped call transactions are recorded in stockholders’ equity, and they are not accounted for as derivatives and are not remeasured each reporting period. As of December 31, 2020, the Company had not purchased any shares under the convertible note capped call transactions.

Prepaid Forward

In connection with the offering of the Convertible Notes, the Company entered into a prepaid forward stock repurchase transaction (“Prepaid Forward”) with a financial institution (“Forward Counterparty”). Pursuant to the Prepaid Forward, the Company used approximately $55.0 million of the net proceeds from the offering of the Convertible Notes to fund the Prepaid Forward. The aggregate number of shares of the Company’s common stock underlying the Prepaid Forward was approximately 1,994,198. The expiration date for the Prepaid Forward is November 15, 2025, although it may be settled earlier in whole or in part. Upon settlement of the Prepaid Forward, at expiration or upon any early settlement, the Forward Counterparty will deliver to the Company the number of shares of common stock underlying the Prepaid Forward or the portion thereof being settled early. The shares purchased under the Prepaid Forward are treated as treasury stock and not outstanding for purposes of the calculation of basic and diluted earnings per share, but will remain outstanding for corporate law purposes, including for purposes of any future stockholders’ votes, until the Forward Counterparty delivers the shares underlying the Prepaid Forward to the Company. The Company’s Prepaid Forward hedge transaction exposes the Company to credit risk to the extent that its counterparty may be unable to meet the terms of the transaction. The Company mitigates this risk by limiting its counterparty to a major financial institution.

Stock Compensation

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock Compensation

2017 Inducement Equity Plan

In May 2017, the Company's board of directors approved the 2017 Inducement Equity Plan (the "2017 Plan"). The number of shares of common stock available for awards under the 2017 Plan was set to 750,000, with any shares of common stock that are forfeited, cancelled, held back upon the exercise or settlement of an award to cover the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of common stock, or otherwise terminated (other than by exercise) under the 2017 Plan added back to the shares of common stock available for issuance under the 2017 Plan. The 2017 Plan provides for the granting of stock options, stock appreciation rights, restricted stock awards, restricted stock units ("RSUs"), unrestricted stock awards and dividend equivalent rights.

In November 2019, the Company's board of directors approved an amendment to the 2017 Plan to increase the number of shares of common stock available for issuance under the 2017 Plan by 400,000 shares.

2013 Stock Option and Incentive Plan

In May 2015, the Company’s stockholders approved the amended and restated 2013 Stock Option and Incentive Plan (as amended, the “2013 Plan”) which, among other things, increased the number of shares of common stock reserved for issuance

thereunder. The number of shares of common stock available for awards under the 2013 Plan was increased by 923,622 shares from 2,051,378 shares to 2,975,000 shares, plus (i) shares of common stock that are forfeited, cancelled, held back upon the exercise or settlement of an award to cover the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of common stock or otherwise terminated (other than by exercise) under the 2013 Plan and the Company’s 2008 Incentive Stock Option and Restricted Stock Plan are added back to the shares of common stock available for issuance under the 2013 Plan, and (ii) on January 1, 2016, and each January 1, thereafter, the number of shares of common stock reserved and available for issuance under the 2013 Plan will be cumulatively increased by 2.5% of the number of shares of common stock outstanding on the immediately preceding December 31, or such lesser number of shares of common stock determined by the compensation committee. The 2013 Plan provides for the granting of stock options, stock appreciation rights, restricted stock awards, RSUs, unrestricted stock awards, cash-based awards, performance share awards and dividend equivalent rights.

2008 Stock Option and Restricted Stock Plan

In April 2008, the Company adopted the 2008 Plan, administered by the Board of Directors or a committee appointed by the Board of Directors. The 2008 Plan provides for the granting of stock options and restricted stock to employees and nonemployees of the Company. Options granted under the 2008 Plan may either be incentive stock options, restricted stock awards or nonqualified stock options. Stock options and restricted stock grants may be granted to employees, directors and consultants. Stock awards under the 2008 Plan may be granted for up to ten years from the adoption of the 2008 Plan at prices no less than 100 percent of the fair value of the shares on the date of the grant as determined by (i) the closing price of the Company’s common stock on any national exchange, (ii) the National Association of Securities Dealers Inc. Automated Quotation System (“NASDAQ”), if so authorized for quotation as a NASDAQ security, or (iii) by reasonable application of a reasonable valuation method. The valuation methods utilized by the Company are consistent with the AICPA Technical Practice Aid.

The Company incurs stock-based compensation expense related to stock options and RSUs. The fair value of RSUs is determined by the closing market price of the Company’s common stock on the date of grant. The fair value of stock options is calculated using a Black-Scholes option-pricing model. Compensation costs related to equity instruments granted are recognized over the requisite service periods of the awards on a straight-line basis at the grant-date fair value. The Company accounts for forfeitures as they occur.

Under the 2017 Plan, 2013 Plan and the 2008 Plan the vesting of options granted or restricted awards given will be determined individually with each option grant. Generally, 25 percent of the granted amount will vest upon the first anniversary of the option grant with the remainder vesting ratably on the first day of each calendar quarter for the following three years. Stock options have a 10-year life and expire if not exercised within that period, or if not exercised within 90 days of cessation of providing service to the Company.

Stock Options

The following table summarizes the activity relating to the Company’s options to purchase common stock for the year ended December 31, 2020:


				Weighted-Average
		Weighted-Average		Remaining
	Number of	Exercise Price		Contractual	Aggregate
	Options	Per Share		Term (Years)	Intrinsic Value
					(in thousands)
Outstanding at December 31, 2019	4,677,929	$	39.31	6.82	$	109,054
Granted	234,940	$	61.14
Forfeited or cancelled (vested and unvested)	(436,916)	$	53.95
Exercised	(299,435)	$	22.15
Outstanding at December 31, 2020	4,176,518	$	40.24	5.28	$	18,415

The following table summarizes information about the Company’s stock option plan as of December 31, 2020:


				Weighted-Average
		Weighted-Average		Remaining
	Number of	Exercise Price		Contractual	Aggregate
	Options	Per Share		Term (Years)	Intrinsic Value
					(in thousands)
Vested and expected to vest at December 31, 2020	4,176,518	$	40.24	5.28	$	18,415
Exercisable at December 31, 2020	3,356,739	$	36.96	4.62	$	18,154

The total pre-tax intrinsic value of stock options exercised during the years ended December 31, 2020, 2019 and 2018, was $6.3 million, $17.7 million and $12.1 million, respectively.

The following table shows the weighted-average assumptions used to compute the stock-based compensation costs for the stock options granted to employees during each of the three years ending December 31, 2020, using the Black-Scholes option-pricing model:


	Year ended
	December 31,
	2020		2019		2018
Risk-free interest rate	1.70	%	2.10	%	2.75	%
Dividend yield	—		—		—
Weighted-average expected life of options (years)	6.25		6.25		6.21
Volatility	81	%	73	%	72	%

The risk-free interest rate assumption was based on the United States Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued. The assumed dividend yield was based on the Company’s expectation of not paying dividends in the foreseeable future. The weighted-average expected life of the options was calculated using the simplified method as prescribed by the Securities and Exchange Commission Staff Accounting Bulletin No. 107 (“SAB No. 107”). This decision was based on the lack of relevant historical data due to the Company’s limited historical experience. In addition, due to the Company’s limited historical and predictive data, the estimated volatility incorporates the historical volatility of comparable companies whose share prices are publicly available.

The weighted-average grant-date fair values of stock options granted during the years ended December 31, 2020, 2019 and 2018, were $43.22, $31.18, and $37.56, respectively. During the year ended December 31, 2020, the Company recognized stock-based compensation expense related to stock options of $20.9 million, including $0.6 million that was capitalized into inventory. During the years ended December 31, 2019 and 2018, the Company recognized stock-based compensation expense related to stock options of $23.5 million and $23.4 million, respectively.

As of December 31, 2020, there was approximately $26.8 million of unrecognized compensation cost related to unvested options, which will be recognized over a weighted-average period of approximately 2.0 years.

Restricted Stock Units

The following table summarizes the activity relating to the Company’s RSUs for the year ended December 31, 2020:


	Number of	Weighted-Average
	RSUs	Fair Value Per Share

Outstanding and unvested at December 31, 2019	245,966	$	44.45
Granted	381,396	$	49.14
Forfeited or expired	(113,108)	$	47.15
Vested	(113,020)	$	48.80
Outstanding and unvested at December 31, 2020	401,234	$	46.92

During the year ended December 31, 2020, the Company recognized stock-based compensation expense related to RSUs of $7.0 million, including $0.2 million that was capitalized into inventory. During the years ended December 31, 2019 and 2018, the Company recognized approximately $2.4 million and $0.6 million, respectively, of stock-based compensation expense recognized related to RSUs. As of December 31, 2020, there was approximately $15.6 million of unrecognized stock-based compensation expense related to unvested RSUs, which will be recognized over a weighted-average period of approximately 2.9 years.

Employee Stock Purchase Plan

In April 2020, the board of directors approved the Esperion Therapeutics, Inc. 2020 Employee Stock Purchase Plan (the "ESPP") which was approved by the Company's shareholders on May 28, 2020. The ESPP allows eligible employees to authorize payroll deductions of up to 10% of their base salary or wages up to $25,000 annually to be applied toward the purchase of shares of the Company's common stock on the last trading day of the offering period. Participating employees will purchase shares of the Company's common stock at a discount of up to 15% on the lesser of the closing price of the Company's common stock on the NASDAQ Global Select Market (i) on the first trading day of the offering period or (ii) the last day of any offering period. Offering periods under the ESPP will generally be in six months increments, commencing on September 1 and March 1 of each calendar year with the administrator having the right to establish different offering periods. During the year ended December 31, 2020, the Company recognized $0.5 million of stock compensation expense related to the ESPP. As of December 31, 2020, there have been no shares issued and 825,000 shares reserved for future issuance under the ESPP.

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2020
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit PlanDuring 2008, the Company adopted the Esperion Therapeutics, Inc. 401(k) Plan (the “401(k) Plan”), which qualifies as a deferred salary arrangement under Section 401(k) of the Internal Revenue Code. Under the 401(k) Plan, participating employees may defer a portion of their pretax earnings. The Company may, at its sole discretion, contribute for the benefit of eligible employees. Company contributions to the 401(k) Plan during the years ended December 31, 2020, 2019 and 2018, were $2.7 million, $0.7 million and $0.3 million, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

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-Paragraph 1
-Subparagraph (r)(2)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

Leases

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Leases

LeasesThe Company has operating leases primarily related to the Company's principal executive office, automobile leases and other IT related equipment. The lease for the principal executive office has a lease term of 5 years and the automobile leases and IT equipment leases primarily have a term of 3 years. During year ended December 31, 2020, the right of use operating lease assets and operating lease liabilities recognized on the balance sheet increased by $4.5 million and $4.5 million from December 31, 2019, respectively, due to the addition of automobile leases and IT equipment associated with the onboarding of the Company’s commercial sales force to support the commercialization of NEXLETOL and NEXLIZET. During the years ended December 31, 2020 and December 31, 2019, the Company recognized $2.2 million and $0.3 million, respectively, of operating lease costs, recognized on the statements of operations, and paid cash for the amounts included in the measurement of lease liabilities of $2.2 million and $0.3 million, respectively, which were included in operating cash flows on the statements of

cash flows. At December 31, 2020 and December 31, 2019, the weighted-average remaining lease term of operating leases was 2.3 years and 3.3 years, respectively, and the weighted average discount rate was 3.5% and 6.5%, respectively. There were no right-of-use assets obtained in exchange for lease obligations in the twelve months ended December 31, 2020 and December 31, 2019. The Company had no additional operating and finance leases that have not yet commenced as of December 31, 2020.

The total rent expense for the year ended December 31, 2018, recognized prior to the adoption of ASU 2016-2, was approximately $0.3 million.

The following table summarizes the Company's future maturities of operating lease liabilities as of December 31, 2020:


	(in thousands)
2021	$	2,746
2022	2,711
2023	830

Total lease payments	6,287
Less imputed interest	246
Total	$	6,041

The following table summarizes supplemental balance sheet information related to leases as of December 31, 2020:


Operating Leases	(in thousands)

Total right of use operating lease assets	$	6,030

Operating lease liabilities (short-term)	$	2,587
Operating lease liabilities (long-term)	3,454
Total lease obligations under operating leases	$	6,041

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

There was no provision for income taxes for the years ended December 31, 2020, 2019 and 2018, because the Company has incurred operating losses since inception. At December 31, 2020, the Company concluded that it is not more likely than not that the Company will realize the benefit of its deferred tax assets due to its history of losses. Accordingly, a full valuation allowance has been applied against the net deferred tax assets.

On March 27, 2020 the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) was signed into law. In addition to some permanent technical corrections to the Tax Cuts and Jobs Act (TCJA), the law made temporary changes to provide taxpayers with tax relief and incentives due to the Coronavirus. The Act delayed certain changes to NOLs under the TCJA and allow additional NOL carryback periods, allowed for the deferral of payroll tax payments, made changes to the interest expense limitation rules to allow additional expensing amount other changes. The Act did not have a material effect on the Company’s tax provision.

As of December 31, 2020, 2019 and 2018, the Company had net deferred tax assets, before valuation allowance, of approximately $202.8 million, $174.2 million and $152.2 million, respectively. Realization of the deferred assets is dependent upon future taxable income, if any, the amount and timing of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. As of December 31, 2020, 2019 and 2018, the Company had federal net operating loss (“NOL”) carryforwards of approximately $700.7 million, $618.1 million and $539.2 million, respectively. Of the total federal NOL carryforwards, $347.4 million will expire at various dates beginning in 2028, if not utilized; the remaining federal NOLs do not expire. As of December 31, 2020, 2019 and 2018, the Company had state NOL carryforwards of approximately $530.3 million, $527.1 million and $526.6 million, respectively. The state NOL carryforwards will expire at various dates beginning in 2022, if not utilized.

The Company has research and developmental tax credits of $26.1 million. The tax credit carryforwards will expire beginning in 2031, if not utilized.

The Company files income tax returns in the U.S. federal jurisdiction, and various states. With few exceptions, the Company is no longer subject to U.S. federal or state and local income tax examinations by tax authorities for years before 2016.

A reconciliation of the U.S. statutory income tax rate to the Company’s effective tax rate is as follows:


	December 31,
	2020		2019		2018
Federal income tax (benefit) at statutory rate	(21.0)	%	(21.0)	%	(21.0)	%
Change in state tax rate	—	%	(0.2)	%	—	%
Permanent items	0.6	%	(1.0)	%	(0.5)	%
R&D tax credits, net of reserves	(16.3)	%	—	%	—	%
Other	0.8	%	0.7	%	0.5	%
Change in valuation allowance	35.9	%	21.5	%	21.0	%
Effective income tax rate	0.0	%	0.0	%	0.0	%

Under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, or the Code, if a corporation undergoes an “ownership change,” the corporation’s ability to use its pre-change net operating loss carryforwards and other pre-change tax attributes, such as research tax credits, to offset its post-change income may be limited. If the Company experiences a greater than 50 percentage point aggregate change in ownership of certain significant stockholders over a three-year period, a Section 382 ownership change could be deemed to have occurred. If a Section 382 change occurs, the Company’s future utilization of the net operating loss carryforwards and credits as of the ownership change will be subject to an annual limitation under Section 382 of the Internal Revenue Code of 1986, as amended, and similar state provisions. Such an annual limitation may result in the expiration of net operating losses before utilization.

The Company’s reserves related to taxes are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies present related to the tax benefit. The Company recognized $2.6 million for unrecognized income tax benefits for the year ended December 31, 2020. There were no unrecognized income tax benefits for the years ended December 31, 2019. The Company does not expect this amount to change in the next twelve months. At December 31, 2020, all of the amount of unrecognized tax benefits, if recognized, would result in a deferred tax asset and corresponding increase in the entity’s valuation allowance. Such unrecognized tax benefit would not affect the effective rate if recognized.

Significant components of the Company’s deferred tax assets are summarized in the table below:


	December 31,
	2020		2019
	(in thousands)
Deferred tax assets:
Federal and state operating loss carryforwards	$	172,530	$	154,912
Equity compensation	21,454		17,217
R&D tax credits, net of reserves	23,452		—
Other	10,361		2,089
Total deferred tax assets	227,797		174,218
Deferred tax liabilities:
Convertible debt	(24,795)		—
Other	(159)		—
Total deferred tax liabilities	(24,954)		—
Valuation allowance	(202,843)		(174,218)
Net deferred tax assets	$	—	$	—

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Net Loss Per Common Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Net Loss Per Common Share

Basic net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common stock equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, warrants for common stock, stock options, unvested RSUs, shares issuable under the ESPP and shares issuable upon conversion of the convertible notes are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive.

The shares outstanding at the end of the respective periods presented below were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect:


	December 31, 2020	December 31, 2019	December 31, 2018
Warrants for common stock	—	—	8,230
Common shares under option	4,176,518	4,677,929	5,303,723
Unvested RSUs	401,234	245,966	37,475
Shares issuable related to the ESPP	16,828	—	—
Shares issuable upon conversion of convertible notes	8,460,237	—	—
Total potential dilutive shares	13,054,817	4,923,895	5,349,428

Statements of Cash Flows

12 Months Ended

Dec. 31, 2020

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]

Statements of Cash Flows

The following table provides a reconciliation of cash and cash equivalents and restricted cash presented on the balance sheets to the same amounts presented on the statements of cash flows on December 31, 2020 and 2019.


	December 31, 2020		December 31, 2019
Cash and cash equivalents	$	304,962	$	166,130
Restricted cash	—		928
Total cash, cash equivalents and restricted cash shown on the statements of cash flows	$	304,962	$	167,058

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

The following table summarizes the unaudited quarterly financial data for the last two years:


	2020
	March 31		June 30		September 30		December 31
	(in thousands, except share and per share data)
Revenues:
Product sales, net	$	858	$	609	$	3,331	$	8,167
Collaboration revenue	982		211,627		502		1,471
Total Revenues	1,840		212,236		3,833		9,638

Operating expenses:
Cost of goods sold	$	31	$	398	$	275	$	1,688
Research and development	34,702		34,987		35,283		41,964
Selling, general and administrative	41,553		47,681		48,826		61,555
Total operating expenses	76,286		83,066		84,384		105,207

Gain (loss) from operations:	(74,446)		129,170		(80,551)		(95,569)

Interest expense	(4,171)		(4,640)		(4,928)		(8,931)
Other income, net	368		81		42		24
Net gain (loss)	$	(78,249)	$	124,611	$	(85,437)	$	(104,476)

Net gain (loss) per common share – basic (1)	$	(2.84)	$	4.50	$	(3.07)	$	(3.89)
Net gain (loss) per common share – diluted (1)	$	(2.84)	$	4.32	$	(3.07)	$	(3.89)

Weighted-average shares outstanding - basic	27,519,229		27,665,728		27,830,281		26,882,830
Weighted-average shares outstanding - diluted	27,519,229		28,854,445		27,830,281		26,882,830


	2019
	March 31		June 30		September 30		December 31
	(in thousands, except share and per share data)
Revenues:
Collaboration revenue	$	145,419	$	982	$	981	$	982
Total Revenues	145,419		982		981		982

Operating expenses:
Research and development	$	46,308	$	42,788	$	48,281	$	38,234
General and administrative	12,182		13,492		18,468		21,712
Total operating expenses	58,490		56,280		66,749		59,946

Gain (loss) from operations:	86,929		(55,298)		(65,768)		(58,964)

Interest expense	—		—		(3,996)		(4,124)
Other income, net	450		1,077		1,387		1,142
Net income (loss)	$	87,379	$	(54,221)	$	(68,377)	$	(61,946)

Net gain (loss) per common share - basic (1)	$	3.26	$	(2.01)	$	(2.52)	$	(2.26)
Net gain (loss) per common share - diluted (1)	$	3.07	$	(2.01)	$	(2.52)	$	(2.26)

Weighted-average shares outstanding - basic	26,842,785		26,968,818		27,171,769		27,371,067
Weighted-average shares outstanding - diluted	28,449,767		26,968,818		27,171,769		27,371,067

________________________________________________

(1)Due to the use of weighted average shares outstanding for each quarter for calculating net loss per common share, the sum of the quarterly net loss per common share amounts may not equal the net loss per common share amount for the full year.

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared by the Company in accordance with generally accepted accounting principles in the United States of America (“GAAP”).
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with generally accepted accounting principles in the United States requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, net revenues, expenses and related disclosures. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company invests its excess cash in bank deposits, money market accounts, and short-term investments. The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash equivalents are reported at fair value.
Restricted Cash	Restricted Cash Restricted cash consists of legally restricted amounts held by financial institutions pursuant to contractual arrangements.
Investments	Investments Investments are considered to be available-for-sale and are carried at fair value. Unrealized gains and losses, if any, are reported as a separate component of stockholders’ equity. The cost of investments classified as available-for-sale are adjusted for the amortization of premiums and accretion of discounts to maturity and recorded in other income, net. Realized gains and losses, if any, are determined using the specific identification method and recorded in other income, net. Investments with original maturities beyond 90 days at the date of purchase and which mature at, or less than twelve months from, the balance sheet date are classified as current. Investments with a maturity beyond twelve months from the balance sheet date are classified as long-term.
Selling, General and Administrative Expenses	Selling, General and Administrative ExpensesSelling, general and administrative expenses primarily consist of salaries and benefits, stock-based compensation, and costs of programs necessary for the general conduct of the Company's business, including costs associated with the commercialization of NEXLETOL and NEXLIZET in the U.S. Selling, general and administrative expenses are expensed as costs are incurred, services are performed, or goods are delivered. The Company incurred advertising costs of $19.3 million for the year ended December 31, 2020.
Concentration of Credit Risk	Concentration of Credit Risk Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to concentrations of credit risk. The Company has established guidelines for investment of its excess cash and believes the guidelines maintain safety and liquidity through diversification of counterparties and maturities. The Company enters into a limited number of distribution agreements with distributors and specialty pharmacies. The Company's net product sales are with these customers. As of December 31, 2020, eight customers accounted for all of the Company's net trade receivables.
Inventories	Inventories Inventories are stated at the lower of cost or net realizable value and recognized on a first-in, first-out ("FIFO") method. The Company uses standard cost to determine the cost basis for inventory. Inventory is capitalized based on when future economic benefit is expected to be realized. The Company began capitalizing inventory upon receiving FDA approval for NEXLETOL and NEXLIZET on February 21, 2020 and February 26, 2020, respectively. Prior to the FDA approval of NEXLETOL and NEXLIZET, expenses associated with the manufacturing of the Company's products were recorded as research and development expense. The Company analyzes its inventory levels on a periodic basis to determine if any inventory is at risk for expiration prior to sale or has a cost basis that is greater than its estimated future net realizable value. Any adjustments are recognized through cost of goods sold in the period in which they are incurred.
Segment Information	Segment Information The Company views its operations and manages its business in one operating segment, which is the business of researching, developing and commercializing therapies for the treatment of patients with elevated LDL-C.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s cash, cash equivalents, restricted cash and investments are carried at fair value. Financial instruments, including other prepaid and current assets, accounts payable and accrued liabilities are carried at cost, which approximates fair value. Debt is carried at amortized cost, which approximates fair value.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are recorded at cost, less accumulated depreciation. Depreciation is provided using the straight-line method over the estimated useful lives of the respective assets, generally three to ten years. Leasehold improvements are amortized over the lesser of the lease term or the estimated useful lives of the related assets.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. The impairment loss, if recognized, would be based on the excess of the carrying value of the impaired asset over its respective fair value. No impairment losses have been recorded through December 31, 2020.
Leases	Leases The Company reviews all arrangements to determine if the contract contains a lease or an embedded lease using the criteria in Accounting Standards Codification ("ASC") 842 Leases ("ASC 842"). If a lease is identified, the Company reviews the consideration in the contract and separates the lease components from the nonlease components. In addition, the Company reviews the classification of the lease between operating and finance leases. According to ASC 842, lessees should discount lease payments at the lease commencement date using the rate implicit in the lease. If the rate implicit in the lease is not readily determinable, a lessee must use its incremental borrowing rate for purposes of classifying the lease and measuring the right-of-use asset and liability. To the extent the rate is not implicit in the lease, the Company uses the incremental borrowing rate it would have to pay to borrow on a collateralized basis over a similar term in an amount equal to the lease payments in a similar economic environment.
Convertible Notes	Convertible Notes The Company accounts for convertible debt instruments that may be settled in cash or equity upon conversion by separating the liability and equity components of the instruments in a manner that reflects the nonconvertible debt borrowing rate. The Company determined the carrying amount of the liability component of the Convertible Notes by using estimates and assumptions that market participants would use in pricing a debt instrument. These estimates and assumptions are judgmental in nature and could have a significant impact on the determination of the debt component, and the associated non-cash interest expense. The equity component is treated as a discount on the liability component of the Convertible Notes, which is amortized over the term of the Convertible Notes using the effective interest rate method. Debt issuance costs related to the Convertible Notes are allocated to the liability and equity components of the Convertible Notes based on their relative values. Debt issuance costs allocated to the liability component are amortized over the life of the Convertible Notes as additional non-cash interest expense. Transaction costs allocated to equity are netted with the equity component of the convertible debt instrument in stockholders’ equity (deficit).
Revenue Interest Liability	Revenue Interest Liability The revenue interest liability is presented net of deferred issuance costs on the balance sheets. The Company imputes interest expense associated with this liability using the effective interest rate method. The effective interest rate is calculated based on the rate that would enable the debt to be repaid in full over the anticipated life of the arrangement. The interest rate on the liability may vary during the term of the agreement depending on a number of factors, including the level of forecasted net sales. The Company evaluates the interest rate quarterly based on its current net sales forecasts utilizing the prospective method.
Revenue Recognition	Revenue Recognition In accordance with ASC 606, Revenue from Contracts with Customers ("ASC 606"), the Company recognizes revenue when a customer obtains control of promised goods or services, in an amount that reflects the consideration the Company expects to receive in exchange for the goods or services provided. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: identify the contracts with a customer; identify the performance obligations in the contract; determine the transaction price; allocate the transaction price to the performance obligations in the contract; and recognize revenue when or as the entity satisfies a performance obligation. At contract inception the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when or as the performance obligation is satisfied. The Company derives revenue through two primary sources: collaboration revenue and product sales. Collaboration revenue consists of the collaboration payments to the Company for collaboration arrangements outside of the United States for the development, manufacturing and commercialization of the Company's product candidates by the Company's partners and product sales consists of sales of NEXLETOL and NEXLIZET in the United States. a.Collaboration Revenue The Company has entered into agreements related to its activities to develop, manufacture, and commercialize its product candidates. The Company earns collaboration revenue in connection with a collaboration agreement to develop and/or commercialize product candidates where the Company deems the collaborator to be the customer. In accordance with ASC 606, revenue is measured as the amount of consideration expected to be entitled to in exchange for transferring promised goods or providing services to a customer. Revenue is recognized when (or as) the Company satisfies performance obligations under the terms of a contract. Depending on the terms of the arrangement, the Company may defer the recognition of all or a portion of the consideration received as the performance obligations are satisfied. The collaboration agreements may require the Company to deliver various rights, services, and/or goods across the entire life cycle of a product or product candidate. In an agreement involving multiple goods or services promised to be transferred to a customer, the Company must assess, at the inception of the contract, whether each promise represents a separate performance obligation (i.e., is "distinct"), or whether such promises should be combined as a single performance obligation. The terms of the agreements typically include consideration to be provided to the Company in the form of non-refundable up-front payments, development milestones, sales milestones, and royalties on sales of products within a respective territory. The Company recognizes regulatory and approval milestones consideration when it is probable that a future reversal is unlikely to occur. For sales based milestones and royalties based on sales of product in a territory, the Company applies the sales-based royalty exception in ASC 606 to all of these milestones and royalties. At the inception of a contract, the transaction price reflects the amount of consideration the Company expects to be entitled to in exchange for transferring promised goods or services to its customer. In the arrangement where the Company satisfies performance obligation(s) during the regulatory phase over time, the Company recognizes collaboration revenue typically using an input method on the basis of regulatory costs incurred relative to the total expected cost which determines the extent of progress toward completion. The Company reviews the estimate of the transaction price and the total expected cost each period, and makes revisions to such estimates as necessary. Under contracted supply agreements with collaborators, the Company may manufacture and supply quantities of active pharmaceutical ingredient (“API”) or bulk tablets reasonably required by collaboration partners for the development or sale of licensed products in their respective territory. The Company recognizes revenue when the collaboration partner has obtained control of the API or bulk tablets. The Company records the costs related to the supply agreement in cost of goods sold on the statements of operations and comprehensive income (loss). Under the Company's collaboration agreements, product sales and cost of sales may be recorded by the Company's collaborators as they are deemed to be the principal in the transaction. The Company receives royalties from the commercialization of such products, and records its share of the variable consideration, representing a percentage of net product sales, as collaboration revenue in the period in which such underlying sales occur and costs are incurred by the collaborators. The collaborators will provide the Company with estimates of its royalties for such quarter; these estimates are reconciled to actual results in the subsequent quarter, and the royalty is adjusted accordingly, as necessary. Please refer to the discussion in Note 3 "Collaborations with Third Parties" for further discussion of the accounting related to the collaboration agreements. b.Product Sales, Net On March 30, 2020, NEXLETOL was commercially available in the U.S. through prescription and on June 4, 2020, NEXLIZET was commercially available in the U.S. through prescription. Net product sales totaled $13.0 million for the year ended December 31, 2020. The Company sells NEXLETOL and NEXLIZET to wholesalers in the U.S and recognizes revenue at the point in time when the customer is deemed to have obtained control of the product. The customer is deemed to have obtained control of the product at the time of physical receipt of the product at the customers’ distribution facilities, or free on board (“FOB”) destination, the terms of which are designated in the contract. Product sales are recorded at the net selling price, which includes estimates of variable consideration for which reserves are established for (a) rebates and chargebacks, (b) co-pay assistance programs, (c) distribution fees, (d) product returns, and (e) other discounts and fees. Where appropriate, these estimates take into consideration a range of possible outcomes which are probability-weighted for relevant factors such as current contractual and statutory requirements, and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company's best estimates of the amount of consideration to which it is entitled based on the terms of the applicable contract. The amount of variable consideration may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Given the early stage of the Company’s commercial operations it has provided constraint of its variable consideration due to its potential consumption trends. Actual amounts of consideration ultimately received may differ from the Company's estimates. If actual results in the future vary from estimates, the Company adjusts these estimates, which would affect net product revenue and earnings in the period such variances become known. Liabilities for co-pay assistance, expected product returns, rebates, and distributor fees are classified as “Other accrued liabilities” in the balance sheets. Discounts, such as prompt pay discounts, and chargebacks are recorded as a reduction to trade accounts receivable, which is included in “Other prepaid and current assets” in the balance sheets. Forms of Variable Consideration Rebates and Chargebacks: The Company estimates reductions to product sales for Public Health Service Institutions, such as Medicaid, Medicare and Veterans' Administration ("VA") programs, as well as certain other qualifying federal and state government programs, and other group purchasing organizations. The Company estimates these reductions based upon the Company's contracts with government agencies and other organizations, statutorily defined discounts and estimated payor mix. These organizations purchase directly from the Company's wholesalers at a discount and the wholesalers charge the Company back the difference between the wholesaler price and the discounted price. The Company's liability for Medicare and Medicaid rebates consists of estimates for claims that a state will make for a current quarter. The Company's reserve for this discounted pricing is based on expected sales to qualified healthcare providers and the chargebacks that customers have already claimed. Co-pay assistance: Eligible patients who have commercial insurance may receive assistance from the Company to reduce the patient's out of pocket costs. The Company will buy down the difference between the amount of the eligible patient's co-pay when the drug is purchased at the pharmacy at a determined price. Liabilities for co-pay assistance are calculated by actual program participation from third-party administrators. Distribution Fees: The Company has written contracts with its customers that include terms for distribution fees and costs for inventory management. The Company estimates and records distribution fees due to its customers based on gross sales. Product Returns: The Company generally offers a right of return based on the product’s expiration date and certain spoilage and damaged instances. The Company estimates the amount of product sales that may be returned and records the estimate as a reduction of product sales in the period the related product sales is recognized. The Company’s estimates for expected returns are based primarily on an ongoing analysis of sales information and visibility into the inventory remaining in the distribution channel. Discounts: The Company provides product discounts, such as prompt pay discounts, to its customers. The Company estimates cash discounts based on terms in negotiated contracts and the Company’s expectations regarding future payment patterns.
Cost of Goods Sold	Cost of Goods SoldCost of goods sold is related to the Company's net product sales of NEXLETOL and NEXLIZET and the cost of the API supplied to collaboration partners from supply agreements. Cost of goods sold includes the actual product costs, including inbound freight charges and certain outbound freight charges, purchasing, sourcing, inspection and receiving costs.
Research and Development	Research and Development Research and development expenses consist of costs incurred to further the Company’s research and development activities and include salaries and related benefits, costs associated with clinical activities, nonclinical activities, regulatory activities, manufacturing activities to support clinical activities and commercial product manufacturing supply prior to the Company's regulatory approval, research-related overhead expenses, in-licensing agreements and fees paid to external service providers that conduct certain research and development, clinical, and manufacturing activities on behalf of the Company. Research and development costs are expensed as incurred. In accordance with ASC 730, Research and Development, costs incurred in obtaining in-licenses are charged to research and development expense if the in-licensed technology has not reached commercial feasibility and has no alternative future use. Such licenses purchased by the Company require substantial completion of research and development, regulatory and marketing approval efforts in order to reach commercial feasibility and has no alternative future use.
Accrued Clinical Development Costs	Accrued Clinical Development Costs Outside research costs are a component of research and development expense. These expenses include fees paid to clinical research organizations and other service providers that conduct certain clinical and product development activities on behalf of the Company. Depending upon the timing of payments to the service providers, the Company recognizes prepaid expenses or accrued expenses related to these costs. These accrued or prepaid expenses are based on management’s estimates of the work performed under service agreements, milestones achieved and experience with similar contracts. The Company monitors each of these factors and adjusts estimates accordingly.
Income Taxes	Income Taxes Deferred tax assets and liabilities are determined based on differences between financial reporting and the tax basis of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company has incurred annual operating losses since inception. Accordingly, it is not more likely than not that the Company will realize a tax benefit from its deferred tax assets and as such, it has recorded a full valuation allowance.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation in accordance with the provisions of ASC 718, Compensation—Stock Compensation. Accordingly, compensation costs related to equity instruments granted are recognized over the requisite service periods of the awards on a straight-line basis at the grant-date fair value calculated using a Black-Scholes option-pricing model. The Company accounts for forfeitures as they occur. Expense is recognized during the period the related services are rendered.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the FASB issued Accounting Standard Update ("ASU") 2016-13, Financial Instruments—Credit Losses (Topic 326), which requires financial instruments to be recognized at an estimate of current expected credit losses. As part of the ASU, financial assets measured at amortized cost will be presented at the net amount expected to be collected. In addition, companies will recognize an allowance for credit losses on available-for-sale investments rather than reducing the amortized cost in an other-than-temporary impairment. The standard is effective for public companies for fiscal years beginning after December 15, 2019, and interim periods within those years. The Company has chosen the practical expedient to exclude accrued interest from both the fair value and the amortized cost basis of available-for-sale debt securities in identifying and measuring an impairment. The Company adopted the standard effective January 1, 2020. The adoption of this standard did not have a material impact on the Company’s balance sheets, statements of operations or statements of cash flows. In August 2018, the FASB issued ASU 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which includes provisions to clarify customer’s accounting for implementation costs incurred in a cloud computing arrangement. Under the updated guidance, a customer in a cloud computing arrangement that is a service contract should follow the internal-use software guidance to determine how to account for costs incurred in implementation. The updated guidance also requires certain classification on the balance sheets, statements of operations and statements of cash flows as well as additional quantitative and qualitative disclosures. The standard is effective for public companies for fiscal years beginning after December 15, 2019, and interim periods within those years. Entities can choose to adopt the new guidance prospectively or retrospectively. The Company adopted the standard effective January 1, 2020, and has chosen to adopt the standard prospectively. Implementation costs for cloud computing arrangements are capitalized in "Other prepaid and current assets" on the Company's balance sheets. The adoption of this standard did not have a material impact to the Company’s balance sheets, statements of operations or statements of cash flows. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, as part of its initiative to reduce complexity in accounting standards. The amendments in this update simplify the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. The amendments within ASU 2019-12 are effective for financial statements issued for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, and early adoption is permitted. The Company early adopted this standard for the year ended December 31, 2020, which amended the existing standards for income tax accounting, eliminating the legacy exception on how to allocate income tax expense or benefit for the year to continuing operations, discontinued operations, other comprehensive income, and other charges or credits recorded directly to shareholder’s equity. We did not adjust comparative periods in our financial statements prior to that period. Adoption of the new standard on January 1, 2020 resulted in determining the tax effect of income or loss from continuing operations using a computation that does not consider the tax effects of items that are not included in continuing operations. As such, the Company did not record a tax expense or benefit related to amounts credited directly to shareholder equity. Refer to Note 16 for additional information. In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”). This ASU simplifies the accounting for convertible instruments by removing the separation models for convertible debt with cash conversion features and convertible instruments with a beneficial conversion feature, which requires the fair value of the embedded conversion feature of convertible instruments be allocated to equity. Under ASU 2020-06, a convertible debt instrument with those features will generally be reported as a single liability at its amortized cost with no separate accounting for the embedded conversion features in equity. The adoption of this ASU will result in the reclassification of the portion of the Company's convertible notes from equity to debt, which will also reduce reported interest expense and increase reported net income. ASU 2020-06 requires the application of the if-converted method when calculating diluted earnings per share, eliminating the Company’s ability to use the treasury stock method when certain conditions are met. The ASU is effective for annual reporting periods beginning after December 15, 2021, with early adoption permitted no earlier than fiscal years beginning after December 15, 2020. The Company plans to early adopt this standard as of January 1, 2021 which will result in a net increase in the Convertible notes of approximately $92.0 million, an adjustment to accumulated deficit of approximately $1.5 million, and a reduction to additional paid-in capital of $93.5 million. The Company does not expect any tax impact of the adoption to be material.

Inventories (Tables)

12 Months Ended

Dec. 31, 2020

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventories consist of the following:


	December 31,
	2020		2019
	(in thousands)
Raw materials	$	13,788	—
Work in process	2,028		—
Finished goods	320		—
	$	16,136	$	—

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment consist of the following:


	December 31,
	2020		2019
	(in thousands)

Computer equipment	$	278	$	256
Software	1,100		615
Furniture, fixtures and other	1,170		908
Leasehold improvements	299		298
Assets in Progress	—		99
Subtotal	2,847		2,176
Less accumulated depreciation and amortization	1,571		1,031
Property and equipment, net	$	1,276	$	1,145

Other Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Payables and Accruals [Abstract]

Schedule of Other Accrued Liabilities

Other accrued liabilities consist of the following:


	December 31,
	2020		2019
	(in thousands)
Accrued compensation	$	15,161	$	7,818
Accrued professional fees	3,183		3,842
Accrued other	6,446		211
Total other accrued liabilities	$	24,790	$	11,871

Investments (Tables)

12 Months Ended

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Schedule of Company's Cash Equivalents and Investments

The following table summarizes the Company’s cash equivalents and investments:


	December 31, 2020
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
	(in thousands)
Cash equivalents:
Money market funds	$	281,783	$	—	$	—	$	281,783






Total	$	281,783	$	—	$	—	$	281,783


	December 31, 2019
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
	(in thousands)
Cash equivalents:
Money market funds	$	20,970	$	—	$	—	$	20,970
U.S. treasury notes	2,497		—		—		2,497
Commercial paper	4,494		—		—		4,494
Short-term investments:
Certificates of deposit	245		—		—		245
U.S. treasury notes	29,155		23		—		29,178
Commercial paper	5,228		—		—		5,228
Total	$	62,589	$	23	$	—	$	62,612

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of the Company's Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following table presents the Company’s financial assets that have been measured at fair value on a recurring basis:


Description	Total		Level 1		Level 2		Level 3

December 31, 2020

Money market funds	$	281,783	$	281,783	$	—	$	—




Total assets at fair value	$	281,783	$	281,783	$	—	$	—
December 31, 2019

Money market funds	$	20,970	$	20,970	$	—	$	—
Investments:
Certificates of deposit	245		245		—		—
U.S. treasury notes	31,675		31,675		—		—
Commercial paper	9,722		—		9,722		—
Total assets at fair value	$	62,612	$	52,890	$	9,722	$	—

Liability Related to the Revenue Interest Purchase Agreement (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Revenue Interest Liability Activity

The following table summarizes the revenue interest liability activity during the year ended December 31, 2020:


	(in thousands)
Revenue interest liability at December 31, 2019	$	132,544
Oberland funding for regulatory approval of NEXLETOL	25,000
Interest expense recognized	19,560
Revenue interest payments	(500)
Revenue interest liability at December 31, 2020	$	176,604

Convertible Notes (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Summary of Convertible Debt

The Convertible Notes consist of the following at December 31, 2020 (in thousands):


Principal amounts:
	Principal	$	280,000
	Unamortized debt discount	(94,900)
	Unamortized debt issuance cost	(5,733)
	Net carrying amount of the debt component	$	179,367

Stock Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Summary of Activity Relating to the Company's Options to Purchase Common Stock

The following table summarizes the activity relating to the Company’s options to purchase common stock for the year ended December 31, 2020:


				Weighted-Average
		Weighted-Average		Remaining
	Number of	Exercise Price		Contractual	Aggregate
	Options	Per Share		Term (Years)	Intrinsic Value
					(in thousands)
Outstanding at December 31, 2019	4,677,929	$	39.31	6.82	$	109,054
Granted	234,940	$	61.14
Forfeited or cancelled (vested and unvested)	(436,916)	$	53.95
Exercised	(299,435)	$	22.15
Outstanding at December 31, 2020	4,176,518	$	40.24	5.28	$	18,415

Summary of Information on the Company's Stock Option Plan

The following table summarizes information about the Company’s stock option plan as of December 31, 2020:


				Weighted-Average
		Weighted-Average		Remaining
	Number of	Exercise Price		Contractual	Aggregate
	Options	Per Share		Term (Years)	Intrinsic Value
					(in thousands)
Vested and expected to vest at December 31, 2020	4,176,518	$	40.24	5.28	$	18,415
Exercisable at December 31, 2020	3,356,739	$	36.96	4.62	$	18,154

Schedule of Weighted-Average Assumptions Used to Compute the Stock-Based Compensation Costs for the Stock Options Granted to Employees


	Year ended
	December 31,
	2020		2019		2018
Risk-free interest rate	1.70	%	2.10	%	2.75	%
Dividend yield	—		—		—
Weighted-average expected life of options (years)	6.25		6.25		6.21
Volatility	81	%	73	%	72	%

Summary of Activity Relating to the Company's RSUs

The following table summarizes the activity relating to the Company’s RSUs for the year ended December 31, 2020:


	Number of	Weighted-Average
	RSUs	Fair Value Per Share

Outstanding and unvested at December 31, 2019	245,966	$	44.45
Granted	381,396	$	49.14
Forfeited or expired	(113,108)	$	47.15
Vested	(113,020)	$	48.80
Outstanding and unvested at December 31, 2020	401,234	$	46.92

Leases (Tables)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Schedule of Future Maturities of Operating Lease Liabilities

The following table summarizes the Company's future maturities of operating lease liabilities as of December 31, 2020:


	(in thousands)
2021	$	2,746
2022	2,711
2023	830

Total lease payments	6,287
Less imputed interest	246
Total	$	6,041

Schedule of Supplemental Balance Sheet Information Related to Leases

The following table summarizes supplemental balance sheet information related to leases as of December 31, 2020:


Operating Leases	(in thousands)

Total right of use operating lease assets	$	6,030

Operating lease liabilities (short-term)	$	2,587
Operating lease liabilities (long-term)	3,454
Total lease obligations under operating leases	$	6,041

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of the U.S. Statutory Income Tax Rate to the Company's Effective Tax Rate

A reconciliation of the U.S. statutory income tax rate to the Company’s effective tax rate is as follows:


	December 31,
	2020		2019		2018
Federal income tax (benefit) at statutory rate	(21.0)	%	(21.0)	%	(21.0)	%
Change in state tax rate	—	%	(0.2)	%	—	%
Permanent items	0.6	%	(1.0)	%	(0.5)	%
R&D tax credits, net of reserves	(16.3)	%	—	%	—	%
Other	0.8	%	0.7	%	0.5	%
Change in valuation allowance	35.9	%	21.5	%	21.0	%
Effective income tax rate	0.0	%	0.0	%	0.0	%

Schedule of Significant Components of the Company's Deferred Tax Assets

Significant components of the Company’s deferred tax assets are summarized in the table below:


	December 31,
	2020		2019
	(in thousands)
Deferred tax assets:
Federal and state operating loss carryforwards	$	172,530	$	154,912
Equity compensation	21,454		17,217
R&D tax credits, net of reserves	23,452		—
Other	10,361		2,089
Total deferred tax assets	227,797		174,218
Deferred tax liabilities:
Convertible debt	(24,795)		—
Other	(159)		—
Total deferred tax liabilities	(24,954)		—
Valuation allowance	(202,843)		(174,218)
Net deferred tax assets	$	—	$	—

Net Loss Per Common Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Schedule of Shares Outstanding Excluded from Computation of Earnings Per Share

The shares outstanding at the end of the respective periods presented below were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect:


	December 31, 2020	December 31, 2019	December 31, 2018
Warrants for common stock	—	—	8,230
Common shares under option	4,176,518	4,677,929	5,303,723
Unvested RSUs	401,234	245,966	37,475
Shares issuable related to the ESPP	16,828	—	—
Shares issuable upon conversion of convertible notes	8,460,237	—	—
Total potential dilutive shares	13,054,817	4,923,895	5,349,428

Statements of Cash Flows (Tables)

12 Months Ended

Dec. 31, 2020

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]

Schedule of Reconciliation of Cash and Cash Equivalents and Restricted Cash


	December 31, 2020		December 31, 2019
Cash and cash equivalents	$	304,962	$	166,130
Restricted cash	—		928
Total cash, cash equivalents and restricted cash shown on the statements of cash flows	$	304,962	$	167,058

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Schedule of Unaudited Quarterly Financial Data

The following table summarizes the unaudited quarterly financial data for the last two years:


	2020
	March 31		June 30		September 30		December 31
	(in thousands, except share and per share data)
Revenues:
Product sales, net	$	858	$	609	$	3,331	$	8,167
Collaboration revenue	982		211,627		502		1,471
Total Revenues	1,840		212,236		3,833		9,638

Operating expenses:
Cost of goods sold	$	31	$	398	$	275	$	1,688
Research and development	34,702		34,987		35,283		41,964
Selling, general and administrative	41,553		47,681		48,826		61,555
Total operating expenses	76,286		83,066		84,384		105,207

Gain (loss) from operations:	(74,446)		129,170		(80,551)		(95,569)

Interest expense	(4,171)		(4,640)		(4,928)		(8,931)
Other income, net	368		81		42		24
Net gain (loss)	$	(78,249)	$	124,611	$	(85,437)	$	(104,476)

Net gain (loss) per common share – basic (1)	$	(2.84)	$	4.50	$	(3.07)	$	(3.89)
Net gain (loss) per common share – diluted (1)	$	(2.84)	$	4.32	$	(3.07)	$	(3.89)

Weighted-average shares outstanding - basic	27,519,229		27,665,728		27,830,281		26,882,830
Weighted-average shares outstanding - diluted	27,519,229		28,854,445		27,830,281		26,882,830


	2019
	March 31		June 30		September 30		December 31
	(in thousands, except share and per share data)
Revenues:
Collaboration revenue	$	145,419	$	982	$	981	$	982
Total Revenues	145,419		982		981		982

Operating expenses:
Research and development	$	46,308	$	42,788	$	48,281	$	38,234
General and administrative	12,182		13,492		18,468		21,712
Total operating expenses	58,490		56,280		66,749		59,946

Gain (loss) from operations:	86,929		(55,298)		(65,768)		(58,964)

Interest expense	—		—		(3,996)		(4,124)
Other income, net	450		1,077		1,387		1,142
Net income (loss)	$	87,379	$	(54,221)	$	(68,377)	$	(61,946)

Net gain (loss) per common share - basic (1)	$	3.26	$	(2.01)	$	(2.52)	$	(2.26)
Net gain (loss) per common share - diluted (1)	$	3.07	$	(2.01)	$	(2.52)	$	(2.26)

Weighted-average shares outstanding - basic	26,842,785		26,968,818		27,171,769		27,371,067
Weighted-average shares outstanding - diluted	28,449,767		26,968,818		27,171,769		27,371,067

________________________________________________

The Company and Basis of Presentation (Details) - USD ($) $ in Millions		1 Months Ended
	Apr. 17, 2020	Jun. 30, 2020
Otsuka Pharmaceutical Co Ltd \| Exclusive Development And Commercialization Rights To Nexletol And Nexlizet Tablets
Collaborations with Third Parties
Upfront cash payment	$ 60.0
Potential additional future payments	$ 450.0
Otsuka Pharmaceutical Co Ltd \| Exclusive Development And Commercialization Rights To Nexletol And Nexlizet Tablets \| Minimum
Collaborations with Third Parties
Percentage of royalties to be received on the net sales	15.00%
Otsuka Pharmaceutical Co Ltd \| Exclusive Development And Commercialization Rights To Nexletol And Nexlizet Tablets \| Maximum
Collaborations with Third Parties
Percentage of royalties to be received on the net sales	30.00%
Daiichi Sankyo Europe GmbH ("DSE") \| Amended License And Collaboration Agreement
Collaborations with Third Parties
Proceeds received upon completion of NUSTENDI MAA transfer		$ 150.0

Summary of Significant Accounting Policies (Details)	3 Months Ended								12 Months Ended
Summary of Significant Accounting Policies (Details)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) segment revenue_source	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2021 USD ($)
Property, Plant and Equipment [Line Items]
Advertising expense									$ 19,300,000
Number of operating segments \| segment									1
Impairment losses									$ 0
Number revenue sources \| revenue_source									2
Total Revenues	$ 9,638,000	$ 3,833,000	$ 212,236,000	$ 1,840,000	$ 982,000	$ 981,000	$ 982,000	$ 145,419,000	$ 227,547,000	$ 148,364,000	$ 0
Convertible notes, net of issuance costs	179,367,000				0				179,367,000	0
Accumulated deficit	838,817,000				695,266,000				838,817,000	695,266,000
Additional paid-in capital	(797,655,000)				$ (715,166,000)				(797,655,000)	(715,166,000)
Cumulative Effect, Period of Adoption, Adjustment \| Subsequent Event
Property, Plant and Equipment [Line Items]
Convertible notes, net of issuance costs												$ 92,000,000.0
Accumulated deficit												1,500,000
Additional paid-in capital												$ 93,500,000
Product
Property, Plant and Equipment [Line Items]
Total Revenues	$ 8,167,000	$ 3,331,000	$ 609,000	$ 858,000					$ 12,965,000	$ 0	$ 0
Property and equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives									3 years
Property and equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives									10 years

Collaborations with Third Parties (Details) - USD ($) $ in Thousands			1 Months Ended		3 Months Ended								12 Months Ended
	Apr. 17, 2020	Jan. 02, 2019	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Collaborations with Third Parties
Revenue					$ 9,638	$ 3,833	$ 212,236	$ 1,840	$ 982	$ 981	$ 982	$ 145,419	$ 227,547	$ 148,364	$ 0
License for Intellectual Property
Collaborations with Third Parties
Revenue														144,400
Ongoing Regulatory and Development Activities
Collaborations with Third Parties
Revenue													1,600	4,000
Regulatory Performance Obligations
Collaborations with Third Parties
Upfront payment									1,600					1,600
Collaboration Revenue
Collaborations with Third Parties
Revenue					$ 1,471	$ 502	$ 211,627	$ 982	$ 982	$ 981	$ 982	$ 145,419	214,582	$ 148,364	$ 0
Daiichi Sankyo Europe GmbH ("DSE") \| NUSTENDI, MAA
Collaborations with Third Parties
Revenue													150,000
Daiichi Sankyo Europe GmbH ("DSE") \| NILEMDO and NUSTENDI, sales of bulk tablets
Collaborations with Third Parties
Revenue													2,800
Collaborative Arrangement \| Daiichi Sankyo Europe GmbH ("DSE")
Collaborations with Third Parties
Upfront cash payment		$ 150,000
Cash payment to the Company upon first commercial sales in the DSE Territory		$ 150,000
Collaborative Arrangement \| Daiichi Sankyo Europe GmbH ("DSE") \| Minimum
Collaborations with Third Parties
Percentage of royalties to be received on the net sales		15.00%
Collaborative Arrangement \| Daiichi Sankyo Europe GmbH ("DSE") \| Maximum
Collaborations with Third Parties
Percentage of royalties to be received on the net sales		25.00%
Collaborative Arrangement \| Serometrix [Member]
Collaborations with Third Parties
Upfront cash payment			$ 12,500
Amended License And Collaboration Agreement \| Daiichi Sankyo Europe GmbH ("DSE")
Collaborations with Third Parties
Proceeds received upon completion of NUSTENDI MAA transfer				$ 150,000
Exclusive Development And Commercialization Rights To Nexletol And Nexlizet Tablets \| Otsuka Pharmaceutical Co Ltd
Collaborations with Third Parties
Upfront cash payment	$ 60,000
Potential additional future payments	$ 450,000
Exclusive Development And Commercialization Rights To Nexletol And Nexlizet Tablets \| Otsuka Pharmaceutical Co Ltd \| Minimum
Collaborations with Third Parties
Percentage of royalties to be received on the net sales	15.00%
Exclusive Development And Commercialization Rights To Nexletol And Nexlizet Tablets \| Otsuka Pharmaceutical Co Ltd \| Maximum
Collaborations with Third Parties
Percentage of royalties to be received on the net sales	30.00%
Milestone payment, first JNDA submissions	$ 20,000
Milestone payment, first NHI Price Listing for NEXLETOL in the Otsuka Territory	70,000
Milestone payment, achievement of the primary MACE in the CLEAR Outcomes study and CV risk reduction rate on the U.S. label	50,000
Milestone payments related to total net sales achievements	$ 310,000
Exclusive Development And Commercialization Rights To Nexletol And Nexlizet Tablets \| Otsuka Pharmaceutical Co Ltd \| Collaboration Revenue
Collaborations with Third Parties
Revenue													$ 60,000

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 13,788	$ 0
Work in process	2,028	0
Finished goods	320	0
Total Inventory	$ 16,136	$ 0

Warrants (Details) - USD ($)		12 Months Ended
Warrants (Details) - USD ($)	Jun. 30, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Warrants
Proceeds from issuance of convertible notes		$ 280,000,000	$ 0	$ 0
Common stock
Warrants
Number of shares issued upon exercise of warrants (in shares)			5,813	159,944
Warrant
Warrants
Warrants exercisable into stock (in shares)	8,230
Exercise price (in dollars per share)	$ 15.19
Fair value of warrants	$ 100,000
Number of warrants exercised (in shares)			8,230	177,123
Warrants outstanding (in shares)		0	0
Term A Loan
Warrants
Maximum borrowing capacity	5,000,000.0
Term A Loan \| Secured promissory notes
Warrants
Proceeds from issuance of convertible notes	$ 5,000,000.0

Commitments and Contingencies (Details) - Inventory supplies of NEXLETOL and NEXLIZET - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenue Interest Purchase Agreement
Initial agreement term		3 years
Renewal period		1 year
Rolling period for minimum purchase order commitments		12 months
Forecast
Revenue Interest Purchase Agreement
Future purchase amounts	$ 19.1

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property and Equipment
Property and equipment, gross	$ 2,847	$ 2,176
Less accumulated depreciation and amortization	1,571	1,031
Property and equipment, net	1,276	1,145
Depreciation expense	547	319	$ 265
Computer equipment
Property and Equipment
Property and equipment, gross	278	256
Software
Property and Equipment
Property and equipment, gross	1,100	615
Furniture, fixtures and other
Property and Equipment
Property and equipment, gross	1,170	908
Leasehold improvements
Property and Equipment
Property and equipment, gross	299	298
Assets in Progress
Property and Equipment
Property and equipment, gross	$ 0	$ 99

Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued compensation	$ 15,161	$ 7,818
Accrued professional fees	3,183	3,842
Accrued other	6,446	211
Total other accrued liabilities	$ 24,790	$ 11,871

Investments - Summary of Cash Equivalents and Short-Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Investments
Amortized Cost	$ 281,783	$ 62,589
Gross Unrealized Gains	0	23
Gross Unrealized Losses	0	0
Estimated Fair Value	281,783	62,612
Cash Equivalents \| Money market funds
Investments
Amortized Cost	281,783	20,970
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 281,783	20,970
Cash Equivalents \| U.S. treasury notes
Investments
Amortized Cost		2,497
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Estimated Fair Value		2,497
Cash Equivalents \| Commercial paper
Investments
Amortized Cost		4,494
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Estimated Fair Value		4,494
Short-term Investments \| U.S. treasury notes
Investments
Amortized Cost		29,155
Gross Unrealized Gains		23
Gross Unrealized Losses		0
Estimated Fair Value		29,178
Short-term Investments \| Commercial paper
Investments
Amortized Cost		5,228
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Estimated Fair Value		5,228
Short-term Investments \| Certificates of deposit
Investments
Amortized Cost		245
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Estimated Fair Value		$ 245

Investments - Narrative (Details) - USD ($)	3 Months Ended								12 Months Ended
Investments - Narrative (Details) - USD ($)	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments
Accretion of premiums and discounts on investments									$ (97,000)	$ (200,000)	$ (217,000)
Other income, net	$ 24,000	$ 42,000	$ 81,000	$ 368,000	$ 1,142,000	$ 1,387,000	$ 1,077,000	$ 450,000	515,000	4,056,000	2,803,000
Reclassification out of Accumulated Other Comprehensive Income
Investments
Other income, net									0
Interest Income
Investments
Interest income on investments									500,000	3,700,000	2,600,000
Other Nonoperating Income (Expense)
Investments
Accretion of premiums and discounts on investments									$ 100,000	$ 300,000	$ 200,000

Fair Value Measurements (Details) - USD ($)	12 Months Ended
Fair Value Measurements (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Fair value measurements
Estimated Fair Value	$ 281,783,000	$ 62,612,000
Transfer of assets between levels	0	0
Transfer of liabilities between levels	0	0
Recurring fair value measurement
Fair value measurements
Total assets at fair value	281,783,000	62,612,000
Recurring fair value measurement \| Money market funds
Fair value measurements
Estimated Fair Value	281,783,000	20,970,000
Recurring fair value measurement \| Certificates of deposit
Fair value measurements
Estimated Fair Value		245,000
Recurring fair value measurement \| U.S. treasury notes
Fair value measurements
Estimated Fair Value		31,675,000
Recurring fair value measurement \| Commercial paper
Fair value measurements
Estimated Fair Value		9,722,000
Recurring fair value measurement \| Level 1
Fair value measurements
Total assets at fair value	281,783,000	52,890,000
Recurring fair value measurement \| Level 1 \| Money market funds
Fair value measurements
Estimated Fair Value	281,783,000	20,970,000
Recurring fair value measurement \| Level 1 \| Certificates of deposit
Fair value measurements
Estimated Fair Value		245,000
Recurring fair value measurement \| Level 1 \| U.S. treasury notes
Fair value measurements
Estimated Fair Value		31,675,000
Recurring fair value measurement \| Level 1 \| Commercial paper
Fair value measurements
Estimated Fair Value		0
Recurring fair value measurement \| Level 2
Fair value measurements
Total assets at fair value	0	9,722,000
Recurring fair value measurement \| Level 2 \| Money market funds
Fair value measurements
Estimated Fair Value	0	0
Recurring fair value measurement \| Level 2 \| Certificates of deposit
Fair value measurements
Estimated Fair Value		0
Recurring fair value measurement \| Level 2 \| U.S. treasury notes
Fair value measurements
Estimated Fair Value		0
Recurring fair value measurement \| Level 2 \| Commercial paper
Fair value measurements
Estimated Fair Value		9,722,000
Recurring fair value measurement \| Level 3
Fair value measurements
Total assets at fair value	0	0
Recurring fair value measurement \| Level 3 \| Money market funds
Fair value measurements
Estimated Fair Value	$ 0	0
Recurring fair value measurement \| Level 3 \| Certificates of deposit
Fair value measurements
Estimated Fair Value		0
Recurring fair value measurement \| Level 3 \| U.S. treasury notes
Fair value measurements
Estimated Fair Value		0
Recurring fair value measurement \| Level 3 \| Commercial paper
Fair value measurements
Estimated Fair Value		$ 0

Liability Related to the Revenue Interest Purchase Agreement - Summary (Details) - USD ($)		1 Months Ended		12 Months Ended
	Jun. 26, 2019	Mar. 31, 2020	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability Related to the Revenue Interest Purchase Agreement
Proceeds from revenue interest liability, net of issuance costs				$ 25,000,000	$ 124,424,000	$ 0
Revenue Interest Purchase Agreement (RIPA)
Liability Related to the Revenue Interest Purchase Agreement
Revenue interest liability				176,604,000	132,544,000
Revenue interest payments				500,000
Interest expense recognized				19,560,000	$ 8,100,000
Revenue Interest Purchase Agreement (RIPA) \| Oberland
Liability Related to the Revenue Interest Purchase Agreement
Proceeds from revenue interest liability	$ 125,000,000.0
Total amount of subsequent installment, subject to RIPA terms and conditions	75,000,000.0
Amount of subsequent installment, subject to regulatory approval	25,000,000.0
Amount of subsequent installment, subject to achievement of Sales Threshold	50,000,000.0
Milestone amount for worldwide sales to receive the Third Payment	$ 100,000,000.0
Trailing number of months sales must be at or above milestone amount	6 months
Revenue interest rate which will take effect if annual net sales equals or exceeds the Sales Threshold by December 31, 2021	2.50%
Initial revenue interest rate	7.50%
Minimum amount of annual net sales to qualify for reduced revenue interest rate by December 31, 2021	$ 350,000,000.0
Percentage of invested capital received by December 31, 2024, to qualify for second reduced revenue interest rate	100.00%
Revenue interest rate if annual net sales equal or exceed the Sales Threshold and if the Purchasers receive 100% of their invested capital by December 31, 2024	0.40%
Percentage of increase in royalty rate upon drawdown of third payment	33.33%
Percentage of revenue interests payment on which agreement terminates	195.00%
Percentage of revenue interests payment on which agreement terminates, if prior to the anniversary of the closing date, if put option is exercised	120.00%
Percentage of revenue interests payment on which agreement terminates, prior to the third anniversary of the closing date, if put option is exercised	175.00%
Percentage of revenue interests payment on which agreement terminates, after the third anniversary of the closing date, if put option is exercised	195.00%
Revenue interest payments			$ 600,000
Repayment amount expected to pay in next twelve months				$ 5,400,000
Proceeds from revenue interest liability, net of issuance costs		$ 25,000,000.0
Effective annual imputed interest rate (as a percent)	10.60%
Revenue Interest Purchase Agreement (RIPA) \| Oberland \| Net Sales Less Than $250 Million
Liability Related to the Revenue Interest Purchase Agreement
Initial revenue interest rate	7.50%
Minimum amount of annual net sales to qualify for reduced revenue interest rate by December 31, 2021	$ 250,000,000
Hypothetical sales generated	100,000,000
Hypothetical repayment obligation	$ 7,500,000
Revenue Interest Purchase Agreement (RIPA) \| Oberland \| Net Sales Greater Than $250 Million But Less Than $350 Million
Liability Related to the Revenue Interest Purchase Agreement
Revenue interest rate which will take effect if annual net sales equals or exceeds the Sales Threshold by December 31, 2021	2.50%
Minimum amount of annual net sales to qualify for reduced revenue interest rate by December 31, 2021	$ 250,000,000
Hypothetical sales generated	100,000,000
Hypothetical repayment obligation	2,500,000
Revenue Interest Purchase Agreement (RIPA) \| Oberland \| Net Sales Greater Than $350 Million
Liability Related to the Revenue Interest Purchase Agreement
Minimum amount of annual net sales to qualify for reduced revenue interest rate by December 31, 2021	350,000,000
Hypothetical sales generated	100,000,000
Hypothetical repayment obligation	$ 2,500,000

Liability Related to the Revenue Interest Purchase Agreement - Summary of Interest Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Liability From Sale Of Future Revenues [Roll Forward]
Oberland funding for regulatory approval of NEXLETOL	$ 25,000
Revenue Interest Purchase Agreement (RIPA)
Liability From Sale Of Future Revenues [Roll Forward]
Revenue interest liability at December 31, 2019	132,544
Interest expense recognized	19,560	$ 8,100
Revenue interest payments	(500)
Revenue interest liability at December 31, 2020	$ 176,604	$ 132,544

Convertible Notes (Details)			12 Months Ended
Convertible Notes (Details)	Nov. 18, 2020 USD ($)	Nov. 16, 2020 USD ($) day $ / shares shares	Dec. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($) $ / shares	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Proceeds from issuance of convertible notes			$ 280,000,000	$ 0	$ 0
Purchase of capped call options associated with convertible notes		$ 46,000,000.0	46,004,000	0	0
Prepayment of forward stock repurchase transaction		$ 55,000,000.0	$ 55,000,000	$ 0	$ 0
Common stock, par value (in dollars per share) \| $ / shares			$ 0.001	$ 0.001
Underlying common stock \| shares		1,994,198
Capped Call \| Common stock
Debt Instrument [Line Items]
Exercise price (in dollars per share) \| $ / shares		$ 55.16
Class of warrant or right, premium percentage		100.00%
Convertible Senior Notes Due 2025 \| Convertible Debt
Debt Instrument [Line Items]
Debt instrument, face amount	$ 280,000,000.0	$ 250,000,000.0
Debt instrument, stated interest rate		4.00%
Proceeds from issuance of convertible notes			$ 280,000,000.0
Debt instrument, additional principal amount		$ 30,000,000.0
Proceeds from debt, net of issuance costs	$ 29,100,000	$ 242,000,000.0	271,100,000
Debt instrument, convertible, conversion ratio		30.2151
Debt instrument, convertible, conversion price (in dollars per share) \| $ / shares		$ 33.096
Net carrying amount of the debt component		$ 177,600,000
Debt instrument, convertible, carrying amount of equity component		93,500,000
Debt issuance costs gross		$ 8,900,000
Debt instrument, term		5 years
Debt instrument, effective interest rate		14.55%
Debt instrument, redemption price, percentage		100.00%
Debt interest expense			3,100,000
Debt Instrument, Fair Value Disclosure			$ 283,400,000
Convertible Senior Notes Due 2025 \| Convertible Debt \| Period One
Debt Instrument [Line Items]
Common stock, par value (in dollars per share) \| $ / shares		$ 0.001
Debt instrument, convertible, threshold percentage of stock price trigger		130.00%
Debt instrument, convertible, threshold trading days \| day		20
Debt instrument, convertible, threshold consecutive trading days \| day		30
Number of business days \| day		5
Number of consecutive trading days \| day		5
Debt instrument, convertible, threshold percentage of last reported sale price		98.00%
Convertible Senior Notes Due 2025 \| Convertible Debt \| Period Two
Debt Instrument [Line Items]
Debt instrument, convertible, threshold percentage of stock price trigger		130.00%
Debt instrument, convertible, threshold trading days \| day		20
Debt instrument, convertible, threshold consecutive trading days \| day		30
Debt instrument, redemption price, percentage		100.00%
Debt instrument, required amount outstanding		$ 125,000,000.0
Convertible Senior Notes Due 2025 \| Convertible Debt \| Long-term Debt
Debt Instrument [Line Items]
Debt issuance costs gross		5,800,000
Convertible Senior Notes Due 2025 \| Convertible Debt \| Additional Paid-In Capital
Debt Instrument [Line Items]
Debt issuance costs gross		$ 3,100,000

Convertible Notes - Summary of Convertible Debt (Details) - Convertible Debt $ in Thousands	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Principal	$ 280,000
Unamortized debt discount	(94,900)
Unamortized debt issuance cost	(5,733)
Net carrying amount of the debt component	$ 179,367

Stock Compensation - Summary of Plans (Details) - shares	1 Months Ended		12 Months Ended
	May 31, 2015	Apr. 30, 2008	Dec. 31, 2020	Nov. 30, 2019	May 31, 2017	Apr. 30, 2015
2017 Inducement Equity Plan
Stock compensation
Number of commons stock shares available for issuance (in shares)				400,000	750,000
2013 Stock Option and Incentive Plan
Stock compensation
Number of commons stock shares available for issuance (in shares)	2,975,000					2,051,378
Increase in number of commons stock shares available for issuance (in shares)	923,622
Increase in common stock shares reserved and available for issuance, as a percentage of common stock shares outstanding	2.50%
2008 Incentive Stock Option and Restricted Stock Plan
Stock compensation
Grant period of stock awards		10 years
Purchase price expressed as a percentage of fair value of shares on the date of grant		100.00%
Vesting percentage on the first anniversary of the option grant			25.00%
Period for which remainder of grant amount will vest on the first day of each calendar quarter			3 years
Expiration period			10 years
Period from cessation of employment within which options expire if not exercised			90 days

Stock Compensation - Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Options
Outstanding at the beginning of period (in shares)	4,677,929
Granted (in shares)	234,940
Forfeited or expired (in shares)	(436,916)
Exercised (in shares)	(299,435)
Outstanding at the end of the period (in shares)	4,176,518	4,677,929
Weighted-Average Exercise Price Per Share
Outstanding at the beginning of period (in dollars per share)	$ 39.31
Granted (in dollars per share)	61.14
Forfeited or expired (in dollars per share)	53.95
Exercised (in dollars per share)	22.15
Outstanding at the end of the period (in dollars per share)	$ 40.24	$ 39.31
Weighted-Average Remaining Contractual Term (Years)
Outstanding	5 years 3 months 10 days	6 years 9 months 25 days
Aggregate Intrinsic Value
Outstanding	$ 18,415	$ 109,054
Information about the stock option plan
Number of Options, vested and expected to vest (in shares)	4,176,518
Number of Options, exercisable (in shares)	3,356,739
Weighted-Average Exercise Price Per Share, vested and expected to vest (in dollars per share)	$ 40.24
Weighted-Average Exercise Price Per Share, exercisable (in dollars per share)	$ 36.96
Weighted-Average Remaining Contractual Term, vested and expected to vest	5 years 3 months 10 days
Weighted-Average Remaining Contractual Term, exercisable	4 years 7 months 13 days
Aggregate Intrinsic Value, vested and expected to vest	$ 18,415
Aggregate Intrinsic Value, exercisable	18,154
Total intrinsic value of stock options exercised	$ 6,300	$ 17,700	$ 12,100

Stock Compensation - Valuation Assumptions (Details)	12 Months Ended
Stock Compensation - Valuation Assumptions (Details)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Risk-free interest rate	1.70%	2.10%	2.75%
Dividend yield	0.00%	0.00%	0.00%
Weighted-average expected life of options (years)	6 years 3 months	6 years 3 months	6 years 2 months 15 days
Volatility	81.00%	73.00%	72.00%

Stock Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock compensation
Weighted-average grant-date fair value (in dollars per share)	$ 43.22	$ 31.18	$ 37.56
Unrecognized stock-based compensation expense, options	$ 26.8
Stock Options
Stock compensation
Stock-based compensation expense	20.9	$ 23.5	$ 23.4
Stock-based compensation expense capitalized into inventory	$ 0.6
Weighted-average period over which remaining unrecognized compensation cost will be recognized	2 years
RSUs
Stock compensation
Stock-based compensation expense	$ 7.0	$ 2.4	$ 0.6
Stock-based compensation expense capitalized into inventory	$ 0.2
Weighted-average period over which remaining unrecognized compensation cost will be recognized	2 years 10 months 24 days
Unrecognized stock-based compensation expense, RSUs	$ 15.6

Stock Compensation - RSUs (Details) - RSUs	12 Months Ended
Stock Compensation - RSUs (Details) - RSUs	Dec. 31, 2020 $ / shares shares
Number of RSUs
Outstanding and unvested at the beginning of period (in shares) \| shares	245,966
Granted (in shares) \| shares	381,396
Forfeited or expired (in shares) \| shares	(113,108)
Vested (in shares) \| shares	(113,020)
Outstanding and unvested at the ending of period (in shares) \| shares	401,234
Weighted-Average Fair Value Per Share
Outstanding and unvested at the beginning of period (in dollars per share) \| $ / shares	$ 44.45
Granted (in dollars per share) \| $ / shares	49.14
Forfeited or expired (in dollars per share) \| $ / shares	47.15
Vested (in dollars per share) \| $ / shares	48.80
Outstanding and unvested at the at the end of the period (in dollars per share) \| $ / shares	$ 46.92

Stock Compensation - Employee Stock Purchase Plan (Details) - Employee Stock - USD ($)		4 Months Ended	12 Months Ended
	May 28, 2020	Sep. 30, 2020	Dec. 31, 2020
Stock compensation
Maximum employee subscription rate	10.00%
Maximum employee subscription amount	$ 25,000
Purchase discount of employee stock	15.00%
Stock plan offering period	6 months
Stock-based compensation expense			$ 500,000
Shares issued (in shares)		0
Shares reserved for future issuance (in shares)		825,000

Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
Employee Benefit Plan (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Contributions to the 401(k) Plan	$ 2.7	$ 0.7	$ 0.3

Leases - Narrative (Details) - USD ($)	12 Months Ended
Leases - Narrative (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases
Increase in right of use assets	$ 4,500,000
Increase in operating lease liabilities		$ 4,500,000
Cash paid for the amounts included in the measurement of lease liabilities	2,200,000	300,000
Operating lease costs	$ 2,200,000	$ 300,000
Weighted-average remaining lease term of operating leases	2 years 3 months 18 days	3 years 3 months 18 days
Weighted average discount rate	3.50%	6.50%
Right of use assets obtained in exchange for lease obligations	$ 0	$ 0
Rent expense (Topic 840)			$ 300,000
Principal Executive Office
Leases
Operating Lease term	5 years
Automobile leases and IT equipment leases
Leases
Operating Lease term	3 years

Leases - Future Maturities and Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
2021	$ 2,746
2022	2,711
2023	830
Total lease payments	6,287
Less imputed interest	246
Total	6,041
Supplemental balance sheet information related to leases
Total right of use operating lease assets	6,030	$ 1,532
Operating lease liabilities (short-term)	2,587	454
Operating lease liabilities (long-term)	3,454	$ 1,109
Total lease obligations under operating leases	$ 6,041

Income Taxes - Summary (Details) - USD ($)	12 Months Ended
Income Taxes - Summary (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Provision for income taxes
Provision for income taxes	$ 0	$ 0	$ 0
Net deferred tax assets, before valuation allowance	202,800,000	174,200,000	152,200,000
Unrecognized tax benefits	2,600,000	0
Research Tax Credit Carryforward
Provision for income taxes
Tax credit carryforward		26,100,000
Federal
Provision for income taxes
Net operating loss carryforwards	700,700,000	618,100,000	539,200,000
Operating loss carryforwards, subject to expiration	347,400,000
State
Provision for income taxes
Net operating loss carryforwards	$ 530,300,000	$ 527,100,000	$ 526,600,000

Income Taxes - Reconciliation (Details)	12 Months Ended
Income Taxes - Reconciliation (Details)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the U.S. statutory income tax rate to the Company's effective tax rate
Federal income tax (benefit) at statutory rate	(21.00%)	(21.00%)	(21.00%)
Change in state tax rate	0.00%	(0.20%)	0.00%
Permanent items	0.60%	(1.00%)	(0.50%)
R&D tax credits, net of reserves	(16.30%)	0.00%	0.00%
Other	0.80%	0.70%	0.50%
Change in valuation allowance	35.90%	21.50%	21.00%
Effective income tax rate	0.00%	0.00%	0.00%

Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Federal and state operating loss carryforwards	$ 172,530	$ 154,912
Equity compensation	21,454	17,217
R&D tax credits, net of reserves	23,452	0
Other	10,361	2,089
Total deferred tax assets	227,797	174,218
Deferred tax liabilities:
Convertible debt	(24,795)	0
Other	(159)	0
Total deferred tax liabilities	(24,954)	0
Valuation allowance	(202,843)	(174,218)
Net deferred tax assets	$ 0	$ 0

Net Loss Per Common Share - Calculation of diluted net loss per share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	13,054,817	4,923,895	5,349,428
Warrant
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	0	0	8,230
Stock Options
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	4,176,518	4,677,929	5,303,723
Unvested RSUs
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	401,234	245,966	37,475
Employee Stock
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	16,828	0	0
Convertible Debt Securities
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	8,460,237	0	0

Statements of Cash Flows (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 304,962	$ 166,130
Restricted cash	0	928
Total cash, cash equivalents and restricted cash shown on the statements of cash flows	$ 304,962	$ 167,058	$ 36,973	$ 34,468

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total Revenues	$ 9,638	$ 3,833	$ 212,236	$ 1,840	$ 982	$ 981	$ 982	$ 145,419	$ 227,547	$ 148,364	$ 0
Operating expenses:
Cost of goods sold	1,688	275	398	31					2,392	0	0
Research and development	41,964	35,283	34,987	34,702	38,234	48,281	42,788	46,308	146,936	175,611	171,488
Selling, general and administrative	61,555	48,826	47,681	41,553					199,615	65,854	33,097
General and administrative					21,712	18,468	13,492	12,182
Total operating expenses	105,207	84,384	83,066	76,286	59,946	66,749	56,280	58,490	348,943	241,465	204,585
Loss from operations	(95,569)	(80,551)	129,170	(74,446)	(58,964)	(65,768)	(55,298)	86,929	(121,396)	(93,101)	(204,585)
Interest expense	(8,931)	(4,928)	(4,640)	(4,171)	(4,124)	(3,996)	0	0	(22,670)	(8,120)	(28)
Other income, net	24	42	81	368	1,142	1,387	1,077	450	515	4,056	2,803
Net loss	$ (104,476)	$ (85,437)	$ 124,611	$ (78,249)	$ (61,946)	$ (68,377)	$ (54,221)	$ 87,379	(143,551)	(97,165)	(201,810)
Net gain (loss) per common share - basic (in dollars per share)	$ (3.89)	$ (3.07)	$ 4.50	$ (2.84)	$ (2.26)	$ (2.52)	$ (2.01)	$ 3.26
Net gain (loss) per common share - diluted (in dollars per share)	$ (3.89)	$ (3.07)	$ 4.32	$ (2.84)	$ (2.26)	$ (2.52)	$ (2.01)	$ 3.07
Weighted-average shares outstanding - basic (in shares)	26,882,830	27,830,281	27,665,728	27,519,229	27,371,067	27,171,769	26,968,818	26,842,785
Weighted-average shares outstanding - diluted (in shares)	26,882,830	27,830,281	28,854,445	27,519,229	27,371,067	27,171,769	26,968,818	28,449,767
Product
Revenues:
Total Revenues	$ 8,167	$ 3,331	$ 609	$ 858					12,965	0	0
Collaboration Revenue
Revenues:
Total Revenues	$ 1,471	$ 502	$ 211,627	$ 982	$ 982	$ 981	$ 982	$ 145,419	$ 214,582	$ 148,364	$ 0