Amphastar Pharmaceuticals (AMPH) 10-K15 Mar 212020 FY Annual reportFinancial data

Company Profile

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2020	Mar. 08, 2021	Jun. 30, 2020
Document and Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	001-36509
Entity Registrant Name	Amphastar Pharmaceuticals, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0702205
Entity Address, Address Line One	11570 6th Street
Entity Address, City or Town	Rancho Cucamonga
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	91730
City Area Code	909
Local Phone Number	980-9484
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	AMPH
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 566,686,688
Entity Common Stock, Shares Outstanding		47,432,937
Entity Central Index Key	0001297184
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current Assets:
Cash and cash equivalents	$ 92,642	$ 73,685
Restricted cash	1,865	1,865
Short-term investments	12,977	11,675
Restricted short-term investments	2,200	2,290
Accounts receivable, net	66,005	45,376
Inventories	96,831	110,501
Income tax refunds and deposits	385	311
Prepaid expenses and other assets	6,777	9,538
Total current assets	279,682	255,241
Property, plant, and equipment, net	260,055	233,856
Finance lease right-of-use assets	612	887
Operating lease right-of-use assets	20,042	18,805
Goodwill and intangible assets, net	40,615	41,153
Other assets	5,250	11,156
Deferred tax assets	24,980	25,873
Total assets	631,236	586,971
Current Liabilities:
Accounts payable and accrued liabilities	95,504	77,051
Income taxes payable	1,077	2,042
Current portion of long-term debt	12,263	7,741
Current portion of operating lease liabilities	3,357	3,175
Total current liabilities	112,201	90,009
Long-term reserve for income tax liabilities	4,709	3,425
Long-term debt, net of current portion	34,186	39,394
Long-term operating lease liabilities, net of current portion	17,464	16,315
Deferred tax liabilities	741	867
Other long-term liabilities	13,212	9,433
Total liabilities	182,513	159,443
Stockholders' equity:
Preferred stock: par value $0.0001; 20,000,000 shares authorized; no shares issued and outstanding
Common stock: par value $0.0001; 300,000,000 shares authorized; 54,760,922 and 47,495,439 shares issued and outstanding as of December 31, 2020 and 52,495,483 and 46,576,968 shares issued and outstanding as of December 31, 2019, respectively	5	5
Additional paid-in capital	410,061	367,305
Retained earnings	117,773	116,370
Accumulated other comprehensive loss	(3,721)	(4,687)
Treasury stock	(121,812)	(97,627)
Total Amphastar Pharmaceuticals, Inc. stockholders' equity	402,306	381,366
Non-controlling Interests	46,417	46,162
Total equity	448,723	427,528
Total liabilities and stockholders' equity	$ 631,236	$ 586,971

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock; shares authorized	300,000,000	300,000,000
Common stock; shares issued	54,760,922	52,495,483
Common stock; shares outstanding	47,495,439	46,576,968

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED STATEMENTS OF OPERATIONS
Net revenues	$ 349,846	$ 322,357	$ 294,666
Cost of revenues	206,506	190,434	187,681
Gross profit	143,340	131,923	106,985
Operating (income) expenses:
Selling, distribution, and marketing	14,780	12,830	8,156
General and administrative	50,377	50,279	49,888
Research and development	67,229	68,853	57,564
Total operating expenses	132,386	131,962	115,608
Income (loss) from operations	10,954	(39)	(8,623)
Non-operating (expenses) income:
Interest income	642	997	456
Interest expense	(374)	(119)	(243)
Other income (expenses), net	(6,585)	59,389	(1,516)
Total non-operating (expenses) income, net	(6,317)	60,267	(1,303)
Income (loss) before income taxes	4,637	60,228	(9,926)
Income tax provision (benefit)	3,540	13,723	(3,266)
Net income (loss)	1,097	46,505	(6,660)
Net income (loss) attributable to non-controlling interests	(306)	(2,434)	(922)
Net income (loss) attributable to Amphastar Pharmaceuticals, Inc.	$ 1,403	$ 48,939	$ (5,738)
Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. stockholders:
Basic (in Dollars per share)	$ 0.03	$ 1.04	$ (0.12)
Diluted (in Dollars per share)	$ 0.03	$ 0.98	$ (0.12)
Weighted-average shares used to compute net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. stockholders:
Basic (in Shares)	47,038	46,982	46,395
Diluted (in Shares)	49,124	49,907	46,395

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss) attributable to Amphastar Pharmaceuticals, Inc.	$ 1,403	$ 48,939	$ (5,738)
Other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc., net of income taxes
Foreign currency translation adjustment	1,121	(576)	(1,957)
Change in pension obligations	(155)	(98)	44
Total other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc.	966	(674)	(1,913)
Total comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc.	$ 2,369	$ 48,265	$ (7,651)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common stock	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total Amphastar Stockholders' Equity [Member]	Non-controlling Interest [Member]	Total
Balance at Dec. 31, 2017	$ 5	$ 313,891	$ 72,642	$ (2,100)	$ (50,702)	$ 333,736
Balance at Dec. 31, 2017								$ 333,736
Balance at Dec. 31, 2017	50,039,212				(3,415,631)
Changes in Stockholders' Equity
Beginning balance adjustment as a result of the adoption of accounting standards			582			582		582
Net income (loss) attributable to Amphastar Pharmaceuticals, Inc.			(5,738)			(5,738)		(5,738)
Other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc.				(1,913)		(1,913)		(1,913)
Proceeds from the private placement of ANP		5,190				5,190	$ 32,846	38,036
Net loss attributable to non-controlling interest							(922)	(922)
Treasury stock acquired					$ (25,047)	(25,047)		(25,047)
Treasury stock acquired (in Shares)					(1,414,924)
Issuance of treasury stock in connection with the Company's equity plans		(273)			$ 273
Issuance of treasury stock in connection with the Company's equity plans (in Shares)					22,998
Issuance of common stock in connection with the Company's equity plans		8,946				8,946		8,946
Issuance of common stock in connection with the Company's equity plans (in Shares)	1,399,463
Share-based compensation expense		16,680				16,680		16,680
Balance at Dec. 31, 2018	$ 5	344,434	67,485	(4,013)	$ (75,476)	332,435	31,924
Balance at Dec. 31, 2018								364,359
Balance at Dec. 31, 2018	51,438,675				(4,807,557)
Changes in Stockholders' Equity
Beginning balance adjustment as a result of the adoption of accounting standards			(54)			(54)		(54)
Net income (loss) attributable to Amphastar Pharmaceuticals, Inc.			48,939			48,939		48,939
Other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc.				(674)		(674)		(674)
Proceeds from the private placement of ANP		2,588				2,588	16,378	18,966
Net loss attributable to non-controlling interest							(2,434)	(2,434)
Treasury stock acquired					$ (22,291)	(22,291)		(22,291)
Treasury stock acquired (in Shares)					(1,122,781)
Issuance of treasury stock in connection with the Company's equity plans		(140)			$ 140
Issuance of treasury stock in connection with the Company's equity plans (in Shares)					11,823
Issuance of common stock in connection with the Company's equity plans		3,421				3,421		3,421
Issuance of common stock in connection with the Company's equity plans (in Shares)	1,056,808
Share-based compensation expense		17,001				17,001	294	17,295
Balance at Dec. 31, 2019	$ 5	367,305	116,370	(4,687)	$ (97,627)	381,366	46,162	381,366
Balance at Dec. 31, 2019								$ 427,528
Balance at Dec. 31, 2019	52,495,483				(5,918,515)			46,576,968
Changes in Stockholders' Equity
Net income (loss) attributable to Amphastar Pharmaceuticals, Inc.			1,403			1,403		$ 1,403
Other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc.				966		966		966
Acquisition of additional ownership interest in ANP							(106)	(106)
Net loss attributable to non-controlling interest							(306)	(306)
Treasury stock acquired					$ (24,425)	(24,425)		(24,425)
Treasury stock acquired (in Shares)					(1,366,915)
Issuance of treasury stock in connection with the Company's equity plans		(240)			$ 240
Issuance of treasury stock in connection with the Company's equity plans (in Shares)					19,947
Issuance of common stock in connection with the Company's equity plans		23,165				23,165		23,165
Issuance of common stock in connection with the Company's equity plans (in Shares)	2,265,439
Share-based compensation expense		19,831				19,831	667	20,498
Balance at Dec. 31, 2020	$ 5	$ 410,061	$ 117,773	$ (3,721)	$ (121,812)	$ 402,306	$ 46,417	402,306
Balance at Dec. 31, 2020								$ 448,723
Balance at Dec. 31, 2020	54,760,922				(7,265,483)			47,495,439

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows From Operating Activities:
Net income (loss)	$ 1,097	$ 46,505	$ (6,660)
Reconciliation to net cash provided by operating activities:
Loss (gain) on impairment and disposal of assets	240	1,036	1,429
Depreciation of property, plant, and equipment	20,491	17,073	14,529
Amortization of product rights, trademarks, and patents	1,036	1,037	1,987
Operating lease right-of-use asset amortization	3,653	3,011
Share-based compensation	20,498	17,295	16,680
Reserve for uncertain tax positions	1,285	3,010	(464)
Changes in deferred taxes, net	(162)	4,542	(1,414)
Changes in operating assets and liabilities:
Accounts receivable, net	(20,160)	6,702	(16,295)
Inventories	15,297	(41,103)	(5,984)
Prepaid expenses and other assets	(2,049)	(3,604)	1,375
Income tax refunds, deposits, and payables, net	(972)	591	3,849
Operating lease liabilities	(3,597)	(2,613)
Accounts payable and accrued liabilities	20,609	(11,720)	29,159
Net cash provided by operating activities	57,266	41,762	38,191
Cash Flows From Investing Activities:
Purchases and construction of property, plant, and equipment	(33,855)	(41,555)	(46,808)
Proceeds from the sale of property, plant and equipment			245
Sale of intangible assets			4,400
Purchase of short-term investments	(13,557)	(8,815)	(308)
Maturity of short-term investments	12,411		91
Payment of deposits and other assets	(1,414)	(157)	198
Net cash used in investing activities	(36,415)	(50,527)	(42,182)
Cash Flows From Financing Activities:
Proceeds from the private placement of ANP		18,298	38,036
Acquisition of additional ownership interest in ANP	(106)
Proceeds from equity plans, net of withholding tax payments	23,165	3,421	8,946
Purchase of treasury stock	(24,425)	(22,291)	(25,047)
Proceeds from borrowing under lines of credit	1,238		347
Repayments under lines of credit		(347)
Proceeds from issuance of long-term debt	6,283	3,570	8,431
Principal payments on long-term debt	(8,401)	(6,434)	(5,705)
Net cash provided by (used in) financing activities	(2,246)	(3,783)	25,008
Effect of exchange rate changes on cash	352	(104)	(274)
Net increase (decrease) in cash, cash equivalents and restricted cash	18,957	(12,652)	20,743
Cash, cash equivalents, and restricted cash at beginning of period	75,550	88,202	67,459
Cash, cash equivalents, and restricted cash at end of period	94,507	75,550	88,202
Noncash Investing and Financing Activities:
Capital expenditure included in accounts payable	11,136	10,622	8,386
Operating lease right-of-use assets	4,819	7,978
Equipment acquired under finance leases	61	143	14
Supplemental Disclosures of Cash Flow Information:
Interest paid, net of capitalized interest	2,199	2,435	2,376
Income taxes paid	$ 3,411	$ 5,717	$ 339

Business

Business	12 Months Ended
Business	Dec. 31, 2020
Business
Business	Note 1. Business Amphastar Pharmaceuticals, Inc., a Delaware corporation (together with its subsidiaries, hereinafter referred to as the “Company”) is a bio-pharmaceutical company that develops, manufactures, markets, and sells generic and proprietary injectable, inhalation, and intranasal products, including products with high technical barriers to market entry. Additionally, the Company sells insulin active pharmaceutical ingredient, or API, products. Most of the Company’s products are used in hospital or urgent care clinical settings and are primarily contracted and distributed through group purchasing organizations and drug wholesalers. The Company’s insulin API products are sold to other pharmaceutical companies for use in their own products and are being used by the Company in the development of injectable finished pharmaceutical products. The Company’s inhalation product, Primatene Mist ®

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2020
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company and its subsidiaries, and are prepared in accordance with United States generally accepted accounting principles, or GAAP. All intercompany activity has been eliminated in the preparation of the consolidated financial statements. In the opinion of management, the accompanying consolidated financial statements include all adjustments necessary to present fairly the consolidated financial position, results of operations, and cash flows of the Company. The Company’s subsidiaries include: (1) International Medication Systems, Limited, or IMS, (2) Armstrong Pharmaceuticals, Inc., or Armstrong, (3) Amphastar Nanjing Pharmaceuticals Inc., or ANP, (4) Nanjing Letop Biological Technology Co., Ltd., or Letop, (5) Nanjing Hanxin Pharmaceutical Technology Co., Ltd., or Hanxin, (6) Nanjing Hanxin Biomedical Testing Service Co., Ltd., or Hanxin Biomedical, (7) Nanjing Baixin Trading Co., Ltd., or Baixin, (8) Amphastar France Pharmaceuticals, S.A.S., or AFP, (9) Amphastar UK Ltd., or AUK, and (10) International Medication Systems (UK) Limited, or IMS UK. In July 2018, the Company’s Chinese subsidiary, ANP, completed a private placement of its common equity interest to accredited investors and received approximately $56.3 million of cash proceeds, a portion of which was received in 2019. The Company has retained approximately 58% of the equity interest in ANP following the private placement and continues to consolidate the financial results of ANP with the Company’s results of operations. ANP’s net income after July 2, 2018, was attributed to the Company in accordance with the Company’s equity interest of approximately 58% in ANP. COVID-19 Pandemic The Company is subject to risks and uncertainties as a result of the novel coronavirus pandemic, or COVID-19. The complete extent of the impact of the COVID-19 pandemic on the Company’s business is highly uncertain and difficult to predict, as the information is constantly evolving. The Company considered the impact of COVID-19 on the assumptions and estimates used to determine the results reported and asset valuations as of December 31, 2020. In March 2020, the World Health Organization declared the outbreak of a novel coronavirus, or COVID-19, as a pandemic, which continues to spread throughout the world, including locations where the Company operates, such as the United States, China and France. The Company has been actively monitoring the COVID-19 pandemic and its impact globally. In late January 2020, China implemented extensive curfews and travel restrictions to control the outbreak, and started easing these restrictions in March. Our business operations in China experienced a temporary disruption but resumed full operation in February 2020. In March 2020, France also implemented a stay-at-home order limiting movement and restricting travel, however, the Company was deemed to be an essential business and was not significantly impacted by the restrictions. In March 2020, the Governors of the States of California and Massachusetts declared a health emergency and issued orders to close all nonessential business; as a bio-pharmaceutical company, the Company was deemed to be an essential businesses. Subsequently, some but not all of the restrictions were lifted in China, France, and states where the Company operates, and most businesses were allowed to reopen. All of the Company’s production facilities continued to operate during the remainder of the year as they had prior to the COVID-19 pandemic with very little change, other than for enhanced safety measures intended to prevent the spread of the virus. It is not possible at this time to estimate the complete impact that COVID-19 could have on the Company’s business, including its customers and suppliers, as the impact will depend on future developments, which are highly uncertain and cannot be predicted. Infections may resurge or become more widespread and the limitation on the Company’s ability to travel and timely sell and distribute its products, as well as any closures or supply disruptions, may be extended for longer periods of time, all of which would have a negative impact on the Company’s business, financial condition and operating results. The Company will continue to monitor the impact of COVID-19 on all aspects of its business. Use of Estimates The preparation of consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. The principal accounting estimates include: determination of allowances for credit losses, allowance for discounts, provision for chargebacks and rebates, provision for product returns, adjustment of inventory to their net realizable values, impairment of long-lived and intangible assets and goodwill, workers’ compensation liabilities, litigation reserves, stock price volatilities for share-based compensation expense, valuation allowances for deferred tax assets, and liabilities for uncertain income tax positions. Foreign Currency The functional currency of the Company, its domestic subsidiaries, its Chinese subsidiary ANP, and its U.K. subsidiary, AUK, is the USD. ANP maintains its books of record in Chinese yuan. These books are remeasured into the functional currency of USD using the current or historical exchange rates. The resulting currency remeasurement adjustments and other transactional foreign currency exchange gains and losses are reflected in the Company’s consolidated statements of operations. The Company’s French subsidiary, AFP, maintains its book of record in euros. ANP’s other Chinese subsidiaries, maintain their books of record in Chinese yuan. AUK’s subsidiary, IMS UK, maintains its book of record in British pounds. These local currencies have been determined to be the subsidiaries’ respective functional currencies. These books of record are translated into USD using average exchange rates during the period. Assets and liabilities are translated at the rate of exchange prevailing on the balance sheet date. Equity is translated at the prevailing rate of exchange at the date of the equity transactions. Translation adjustments are reflected in stockholders’ equity and are included as a component of other accumulated comprehensive income (loss). The unrealized gains or losses of intercompany foreign currency transactions that are of a long-term investment nature are reported in other accumulated comprehensive income (loss). The unrealized gains and losses of intercompany foreign currency transactions that are of a long-term investment nature for the years ended December 31, 2020, 2019, and 2018 were a $3.0 million gain, a $0.7 million loss, and a $1.5 million loss, respectively. Comprehensive Income (Loss) For the years ended December 31, 2020, 2019 and 2018, the Company included its foreign currency translation gain (loss) and change in pension obligation of its defined benefit pension plan as part of its comprehensive income (loss) . Shipping and Handling Costs For the years ended December 31, 2020, 2019, and 2018, the Company included shipping and handling costs of approximately $4.3 million, $4.3 million, and $3.7 million, respectively, in selling, distribution and marketing expenses in the accompanying consolidated statements of operations. Advertising Expense Advertising expenses, primarily associated with Primatene Mist ® Research and Development Costs Research and development costs are charged to expense as incurred and consist of costs incurred to further the Company’s research and development activities. These include salaries and related employee benefits, costs associated with clinical trials, nonclinical research and development activities, regulatory activities, research-related overhead expenses and fees paid to external service providers. The Company may produce or purchase inventories prior to or with the expectation of receiving marketing authorization in the near term, based on operational decisions about the most effective use of existing resources. This inventory is referred to as pre-launch inventory. It is the Company’s accounting policy that the pre-launch inventory is capitalized if it has a probable future economic benefit. If marketing authorization is received and previously expensed pre-launch inventory is sold, such sales may contribute up to a 100% margin to the Company’s operating results. Pre-launch inventory costs include cost of work in process, materials, and finished drug products. As of December 31, 2020, 2019, and 2018, the Company did not have material capitalized pre-launch inventory. Financial Instruments The carrying amounts of cash and cash equivalents, short-term investments, restricted cash and short-term investments, accounts receivable, accounts payable, accrued expenses, and short-term borrowings approximate fair value due to the short maturity of these items. The majority of the Company’s long-term obligations consist of variable rate debt, and their carrying value approximates fair value as the stated borrowing rates are comparable to rates currently offered to the Company for instruments with similar maturities. The Company at times enters into fixed interest rate swap contracts to exchange the variable interest rates for fixed interest rates without the exchange of the underlying notional debt amounts. Such interest rate swap contracts are recorded at their fair values. Cash and Cash Equivalents Cash and cash equivalents consist of cash, money market accounts, certificates of deposit and highly liquid investments purchased with original maturities of three months or less. Short-Term Investments Short-term investments as of December 31, 2020 and 2019 consisted of certificates of deposit and investment grade corporate bonds with original expiration dates within 12 months. Restricted Cash Restricted cash is collateral required for the Company to guarantee certain vendor payments in France. As of December 31, 2020 and 2019, the restricted cash balance was $1.9 million. Restricted Short-Term Investments Restricted short-term investments consist of certificates of deposit that are collateral for standby letters of credit to qualify for workers’ compensation self-insurance. The certificates of deposit have original maturities greater than three months, but less than one year. As of December 31, 2020 and 2019, the balance of restricted short-term investments was $2.2 million and $2.3 million, respectively. Allowance for Credit Losses The Company evaluates the collectability of accounts receivable based on a combination of factors. When the Company is aware of circumstances that may impair a customer’s ability to pay subsequent to the original sale, the Company records a specific allowance to reduce the amounts receivable to the amount that the Company reasonably believes to be collectable. For all other customers, the Company recognizes an allowance for credit losses based on factors that include the length of time the receivables are past due, industry and geographic concentrations, the current economic conditions and historical collection experience. As of December 31, 2020 and 2019, the Company's allowance for credit losses was $1.3 million and $1.1 million, respectively. Inventories Inventories consist of currently marketed products and products manufactured under contract. Inventories are stated using the first-in, first-out method, on a consistent basis. The Company states inventory at the lower of cost and net realizable value. Provisions are made for slow-moving, unsellable, or obsolete items. Net realizable value is determined using the estimated selling price, in the ordinary course of business, less estimated costs to complete and dispose. Property, Plant and Equipment Property, plant and equipment are stated at cost or, in the case of assets acquired in a business combination, at fair value on the purchase date. Depreciation and amortization expense is computed using the straight-line method over the estimated useful lives of the related assets as follows: Buildings 20 - 31 years Machinery and equipment 3 - 12 years Furniture and fixtures 3 - 7 years Automobiles 4 - 5 years Leasehold improvements Lesser of remaining lease term or useful life Intangible Assets Intangible assets with finite lives are amortized using the straight-line method over the period the asset is expected to contribute directly or indirectly to the future cash flows of the Company as follows: Product rights 10 - 15 years Patents 10 - 20 years Land-use rights 37 - 50 years Impairment of Long-Lived Assets, including Identifiable Definite-Lived Intangible Assets The Company reviews long-term and identifiable definite-lived intangible assets or asset groups for impairment when events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable. If the sum of the expected future undiscounted cash flows is less than the carrying amount of the asset or an asset group, further impairment analysis is performed. An impairment loss is measured as the amount by which the carrying amount of the asset or asset groups exceeds the fair value (assets to be held and used) or fair value less cost to sell (assets to be disposed of). The Company also reviews the useful lives of its assets periodically to determine whether events and circumstances warrant a revision to the remaining useful life. Changes in the useful life are adjusted prospectively by revising the remaining period over which the asset is amortized. Deferred Income Taxes The Company utilizes the liability method of accounting for income taxes, under which deferred taxes are determined based on the temporary differences between the financial statements and the tax basis of assets and liabilities using enacted tax rates. A valuation allowance is recorded when it is more likely than not that the deferred tax assets will not be realized. Impairment of Indefinite-Lived Intangible Asset and Goodwill The Company reviews indefinite-lived intangible asset and goodwill for impairment in the fourth quarter of each year or more frequently if indicators of impairment are present. When the Company chooses to perform a qualitative assessment, it evaluates economic, industry and company-specific factors as an initial step. If the Company determines it is more likely than not that the indefinite-lived intangible asset is impaired or the fair value of a reporting unit is less than its carrying amount, further quantitative impairment testing is then performed; otherwise, no further testing is required. An impairment loss is recorded if the asset’s fair value is less than its carrying value. The Company also periodically reviews the indefinite-lived intangible asset to determine if events and circumstances continue to support an indefinite useful life. If the life is no longer indefinite, the asset is tested for impairment. The carrying value, after recognition of any impairment loss, is amortized over its remaining useful life. Self-Insured Claims The Company is primarily self-insured, up to certain limits, for workers’ compensation claims. The Company has purchased stop-loss insurance, which will reimburse the Company for individual claims in excess of $350,000 annually or aggregate claims exceeding $3.5 million annually. Operations are charged with the cost of claims reported and an estimate of claims incurred but not reported. A liability for unpaid claims and the associated claim expenses, including incurred but not reported losses, is actuarially determined and reflected in accrued liabilities in the accompanying consolidated balance sheets. Total expense under the program was approximately $0.5 million, $0.4 million, and $2.6 million, for the years ended December 31, 2020, 2019 and 2018, respectively. The self-insured claims liability was $4.5 million and $4.9 million at December 31, 2020 and 2019, respectively. The determination of such claims and expenses and the appropriateness of the related liability is reviewed periodically and updated, as necessary. Changes in estimates are recorded in the period identified. Business Combinations Business combinations are accounted for using the acquisition method of accounting, which requires an acquirer to recognize the assets acquired and the liabilities assumed at the acquisition date measured at their fair values as of that date. Fair value determinations are based on discounted cash flow analyses or other valuation techniques. In determining the fair value of the assets acquired and liabilities assumed in a material acquisition, the Company may utilize appraisals from third party valuation firms to determine fair values of some or all of the assets acquired and liabilities assumed, or may complete some or all of the valuations internally. In either case, the Company takes full responsibility for the determination of the fair value of the assets acquired and liabilities assumed. The value of goodwill reflects the excess of the fair value of the consideration conveyed to the seller over the fair value of the net assets received. Acquisition-related costs that the Company incurs to effect a business combination are expensed in the periods in which the costs are incurred. When the operations of the acquired businesses were not material to the Company’s consolidated financial statements, no pro forma presentations were disclosed. Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update, or ASU, No. 2016-13 Financial Instruments – Credit Losses In January 2017, the FASB issued ASU No. 2017-04 Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU No. 2018-13 Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU No. 2018-14 Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans In August 2018, the FASB issued ASU No. 2018-15 Customer’s Accounting for Implementation Cost Incurred in a Cloud Computing Arrangement that is a Service Contract The adoption of the guidance did not have a material impact on the Company’s consolidated financial statements and related disclosures. In October 2018, the FASB issued ASU No. 2018-17 Targeted Improvements to Related Party Guidance for Variable Interest Entities In November 2018, the FASB issued ASU No. 2018-18 Clarifying the Interaction between Topic 808 and Topic 606 In December 2019, the FASB issued ASU No. 2019-12 Simplifying the Accounting for Income Taxes (Topic 740) In April 2020, the FASB issued ASU No. 2020-04 Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Reporting

Business Acquisitions

Business Acquisitions	12 Months Ended
Business Acquisitions	Dec. 31, 2020
Business Acquisitions
Business Acquisitions	Note 3. Business Acquisitions Acquisition of fourteen injectable products from Hikma Pharmaceuticals PLC In March 2016, the Company acquired 14 abbreviated new drug applications, or ANDAs, representing 11 different injectable chemical entities from Hikma Pharmaceuticals PLC, or Hikma, for $4.0 million. This transaction was accounted for as a business combination in accordance with ASC 805. The ANDAs were estimated to have a fair value of $4.0 million, and were subject to a straight-line amortization over a useful life of approximately 15 years . In February 2017, the Company sold these products to an unrelated party. (See note 10)

Revenue Recognition

Revenue Recognition	12 Months Ended
Revenue Recognition	Dec. 31, 2020
Revenue Recognition
Revenue Recognition	Note 4. Revenue Recognition In accordance with ASC 606 Revenue from Contracts with Customers Generally, revenue is recognized at the time of product delivery to the Company’s customers. In some cases, revenue is recognized at the time of shipment when stipulated by the terms of the sale agreements. The consideration the Company receives in exchange for its goods or services is only recognized when it is probable that a significant reversal will not occur. The consideration to which the Company expects to be entitled includes a stated list price, less various forms of variable consideration. The Company makes significant estimates for related variable consideration at the point of sale, including chargebacks, rebates, product returns, other discounts and allowances. The Company’s payment terms vary by types and locations of customers and the products or services offered. Payment terms differ by jurisdiction and customer, but payment is generally required in a term ranging from 30 to 75 days from date of shipment or satisfaction of the performance obligation. For certain products or services and certain customer types, we may require payment before products are delivered or services are rendered to customers. Provisions for estimated chargebacks, rebates, discounts, product returns and credit losses are made at the time of sale and are analyzed and adjusted, if necessary, at each balance sheet date. Revenues derived from contract manufacturing services are recognized when third-party products are shipped to customers, and after the customer has accepted test samples of the products to be shipped. The Company’s accounting policy is to review each agreement involving contract development and manufacturing services to determine if there are multiple revenue-generating activities that constitute more than one unit of accounting. Revenues are recognized for each unit of accounting based on revenue recognition criteria relevant to that unit. The Company does not have any revenue arrangements with multiple performance obligations. Provision for Chargebacks and Rebates The provision for chargebacks and rebates is a significant estimate used in the recognition of revenue. Wholesaler chargebacks relate to sales terms under which the Company agrees to reimburse wholesalers for differences between the gross sales prices at which the Company sells its products to wholesalers and the actual prices of such products that wholesalers resell under the Company’s various contractual arrangements with third parties such as hospitals and group purchasing organizations in the United States. Rebates include primarily amounts paid to retailers, payers, and providers in the United States, including those paid to state Medicaid programs, and are based on contractual arrangements or statutory requirements. The Company estimates chargebacks and rebates using the expected value method at the time of sale to wholesalers based on wholesaler inventory stocking levels, historic chargeback and rebate rates, and current contract pricing. The provision for chargebacks and rebates is reflected as a component of net revenues. The following table is an analysis of the chargeback and rebate provision: Year Ended December 31, 2020 2019 (in thousands) Beginning balance $ 21,644 $ 22,423 Provision for chargebacks and rebates 158,152 131,524 Credits and payments issued to third parties (159,416) (132,303) Ending balance $ 20,380 $ 21,644 Changes in the chargeback provision from period to period are primarily dependent on the Company’s sales to its wholesalers, the level of inventory held by wholesalers, and the wholesalers’ customer mix. Changes in the rebate provision from period to period are primarily dependent on retailer’s and other indirect customers’ purchases. The approach that the Company uses to estimate chargebacks has been consistently applied for all periods presented. Variations in estimates have been historically small. The Company continually monitors the provision for chargebacks and rebates and makes adjustments when it believes that the actual chargebacks and rebates may differ from the estimates. The settlement of chargebacks and rebates generally occurs within 30 days to 60 days after the sale to wholesalers. Accounts receivable and/or accounts payable and accrued liabilities are reduced and/or increased by the chargebacks and rebate amounts depending on whether the Company has the right to offset with the customer. Of the provision for chargebacks and rebates as of December 31, 2020 and 2019, $16.4 million and $15.4 million were included in accounts receivable, net, on the consolidated balance sheets, respectively. The remaining provision as of December 31, 2020 and 2019 was $4.0 million and $6.2 million, respectively, which were included in accounts payable and accrued liabilities, respectively. Accrual for Product Returns The Company offers most customers the right to return qualified excess or expired inventory for partial credit; however, API product sales are generally non-returnable. The Company’s product returns primarily consist of the returns of expired products from sales made in prior periods. Returned products cannot be resold. At the time product revenue is recognized, the Company records an accrual for product returns estimated using the expected value method. The accrual is based, in part, upon the historical relationship of product returns to sales and customer contract terms. The Company also assesses other factors that could affect product returns including market conditions, product obsolescence, and the introduction of new competition. Although these factors do not normally give the Company’s customers the right to return products outside of the regular return policy, the Company realizes that such factors could ultimately lead to increased returns. The Company analyzes these situations on a case-by-case basis and makes adjustments to the product return reserve as appropriate. The provision for product returns is reflected as a component of net revenues. The following table is an analysis of the product return liability: Year Ended December 31, 2020 2019 (in thousands) Beginning balance $ 10,339 $ 8,030 Provision for product returns 11,810 7,305 Credits issued to third parties (7,945) (4,996) Ending balance $ 14,204 $ 10,339 Of the provision of product returns as of December 31, 2020 and 2019, $10.2 million and $7.1 million were included in accounts payable and accrued liabilities on the consolidated balance sheets, respectively. The remaining provision as of December 31, 2020 and 2019, of $4.0 million and $3.2 million were included in other long-term liabilities, respectively. For the years ended December 31, 2020 and 2019, the Company’s aggregate product return rate was 1.4% and 1.1% of qualified sales, respectively.

Income (Loss) per Share Attribu

Income (Loss) per Share Attributable to Amphastar Pharmaceuticals, Inc. Stockholders	12 Months Ended
	Dec. 31, 2020
Income (Loss) per Share Attributable to Amphastar Pharmaceuticals, Inc. Stockholders
Income (Loss) per Share Attributable to Amphastar Pharmaceuticals, Inc. Stockholders	Note 5. Income (Loss) per Share Attributable to Amphastar Pharmaceuticals, Inc. Stockholders Basic net income (loss) per share attributable to Amphastar Pharmaceuticals Inc. stockholders is calculated based upon the weighted-average number of shares outstanding during the period. Diluted net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. stockholders gives effect to all potential dilutive shares outstanding during the period, such as stock options, non-vested restricted stock units, and shares issuable under the Company’s Employee Stock Purchase Plan, or ESPP, and the reallocation of net income attributable to non-controlling interest from the assumed dilutive effect of stock options issued under the 2018 ANP Equity Incentive Plan, or the 2018 Plan. For the year ended December 31, 2020, options to purchase 1,917,437 shares of stock with a weighted-average exercise price of $20.85 per share, and the reallocation of net income attributable to non-controlling interest were excluded in the computation of diluted net income per common share attributable to Amphastar Pharmaceuticals, Inc. stockholders because the effect would be anti-dilutive. For the year ended December 31, 2019, options to purchase 803,257 shares of stock with a weighted-average exercise price of $21.99 per share, and the reallocation of net income attributable to non-controlling interest were excluded in the computation of diluted net income per common share attributable to Amphastar Pharmaceuticals, Inc. stockholders because the effect would be anti-dilutive. As the Company reported a net loss for the year ended December 31, 2018, the diluted net loss per share attributable to Amphastar Pharmaceuticals, Inc. stockholders, as reported, equals the basic net loss per share attributable to Amphastar Pharmaceuticals, Inc. stockholders since the effect of the assumed exercise of stock options, vesting of non-vested RSUs, and issuance of common shares under the Company’s ESPP are anti-dilutive. Total stock options, non-vested RSUs, and shares issuable under the Company’s ESPP excluded from the year ended December 31, 2018, net loss per share were 10,105,565 stock options, 1,206,661 non-vested RSUs, and 51,792 shares issuable under the ESPP. The following table provides the calculation of basic and diluted net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders for each of the periods presented: Year Ended December 31, 2020 2019 2018 (in thousands, except per share data) Basic and dilutive numerator: Net income (loss) attributable to Amphastar Pharmaceuticals, Inc. $ 1,403 $ 48,939 $ (5,738) Denominator: Weighted-average shares outstanding — basic 47,038 46,982 46,395 Net effect of dilutive securities: Incremental shares from equity awards 2,086 2,925 — Weighted-average shares outstanding — diluted 49,124 49,907 46,395 Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. stockholders — basic $ 0.03 $ 1.04 $ (0.12) Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. stockholders — diluted $ 0.03 $ 0.98 $ (0.12)

Segment Reporting

Segment Reporting	12 Months Ended
Segment Reporting	Dec. 31, 2020
Segment Reporting
Segment Reporting	Note 6. Segment Reporting The Company’s business is the development, manufacture, and marketing of pharmaceutical products. The Company has identified two reporting segments that each report to the Chief Operating Decision Maker, or CODM, as defined in ASC 280, Segment Reporting. The Company’s performance is assessed and resources are allocated by the CODM based on the following two reportable segments: ● Finished pharmaceutical products ● API The finished pharmaceutical products segment manufactures, markets and distributes Primatene Mist ® Selected financial information by reporting segment is presented below: Year Ended December 31, 2020 2019 2018 (in thousands) Net revenues: Finished pharmaceutical products $ 331,368 $ 302,000 $ 271,059 API 18,478 20,357 23,607 Total net revenues 349,846 322,357 294,666 Gross profit (loss): Finished pharmaceutical products 151,645 136,576 113,220 API (8,305) (4,653) (6,235) Total gross profit 143,340 131,923 106,985 Operating expenses 132,386 131,962 115,608 Income from operations 10,954 (39) (8,623) Non-operating (expense) income (6,317) 60,267 (1,303) Income (loss) before income taxes $ 4,637 $ 60,228 $ (9,926) The Company manages its business segments to the gross profit level and manages its operating and other costs on a company-wide basis. The Company does not identify total assets by segment for internal purposes, as the Company’s CODM does not assess performance, make strategic decisions, or allocate resources based on assets. The amount of net revenues in the finished pharmaceutical product segment is presented below: Year Ended December 31, 2020 2019 2018 (in thousands) Finished pharmaceutical products net revenues: Primatene Mist ® $ 51,725 $ 18,065 $ 3,574 Enoxaparin 48,681 42,695 53,371 Phytonadione 42,646 45,786 41,897 Lidocaine 41,113 46,013 43,328 Naloxone 33,416 34,761 37,195 Epinephrine 23,799 13,885 10,055 Other finished pharmaceutical products 89,988 100,795 81,639 Total finished pharmaceutical products net revenues $ 331,368 $ 302,000 $ 271,059 The amount of depreciation and amortization expense included in cost of revenues, by reporting segments is presented below: Year Ended December 31, 2020 2019 2018 (in thousands) Depreciation and amortization expense Finished pharmaceutical products $ 5,766 $ 5,581 $ 4,872 API 3,264 1,477 1,181 Total depreciation and amortization expense $ 9,030 $ 7,058 $ 6,053 Net revenues and carrying values of long-lived assets by geographic regions are as follows: Net Revenue Long-Lived Assets Year Ended December 31, December 31, 2020 2019 2018 2020 2019 (in thousands) United States $ 333,093 $ 304,896 $ 279,122 $ 129,401 $ 126,383 China 3,161 1,481 — 98,538 81,428 France 13,592 15,980 15,544 52,770 45,737 Total $ 349,846 $ 322,357 $ 294,666 $ 280,709 $ 253,548

Customer and Supplier Concentra

Customer and Supplier Concentration	12 Months Ended
Customer and Supplier Concentration	Dec. 31, 2020
Customer and Supplier Concentration
Customer and Supplier Concentration	Note 7. Customer and Supplier Concentration Customer Concentrations Three large wholesale drug distributors, AmerisourceBergen Corporation, or AmerisourceBergen, Cardinal Health, Inc., or Cardinal, and McKesson Corporation, or McKesson, are all distributors of the Company’s products, as well as suppliers of a broad range of health care products. The Company considers these three customers to be its major customers, as each individually and these customers collectively, represented a significant percentage of the Company’s net revenue for the years ended December 31, 2020, 2019, and 2018, and accounts receivable as of December 31, 2020 and 2019, respectively. The following table provides accounts receivable and net revenue information for these major customers: % of Total Accounts % of Net Receivable Revenue December 31, December 31, Year Ended December 31, 2020 2019 2020 2019 2018 AmerisourceBergen 9 % 13 % 23 % 24 % 27 % McKesson 24 % 34 % 22 % 25 % 27 % Cardinal Health 17 % 17 % 17 % 22 % 21 % Supplier Concentrations The Company depends on suppliers for raw materials, APIs, and other components that are subject to stringent FDA requirements. Some of these materials may only be available from one or a limited number of sources. Establishing additional or replacement suppliers for these materials may take a substantial period of time, as suppliers must be approved by the FDA. Furthermore, a significant portion of raw materials may only be available from foreign sources. If the Company is unable to secure, on a timely basis, sufficient quantities of the materials it depends on to manufacture and market its products, it could have a materially adverse effect on the Company’s business, financial condition, and results of operations.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
Fair Value Measurements	Dec. 31, 2020
Fair Value Measurements
Fair Value Measurements	Note 8. Fair Value Measurements GAAP defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants in the principal or most advantageous market for the asset or liability at the measurement date (an exit price). These standards also establish a hierarchy that prioritizes observable and unobservable inputs used in measuring fair value of an asset or liability, as described below: ● Level 1 – Inputs to measure fair value are based on quoted prices (unadjusted) in active markets on identical assets or liabilities; ● Level 2 – Inputs to measure fair value are based on the following: a) quoted prices in active markets on similar assets or liabilities, b) quoted prices for identical or similar instruments in inactive markets, or c) observable (other than quoted prices) or collaborated observable market data used in a pricing model from which the fair value is derived; and ● Level 3 – Inputs to measure fair value are unobservable and the assets or liabilities have little, if any, market activity; these inputs reflect the Company’s own assumptions about the assumptions that market participants would use in pricing the assets or liabilities based on best information available in the circumstances. As of December 31, 2020, cash equivalents include money market accounts. Short-term investments consist of certificates of deposit as well as investment-grade corporate bonds with original expiration dates within 12 months. The certificates of deposit are carried at amortized cost in the Company’s consolidated balance sheet, which approximates their fair value determined based on Level 2 inputs. The corporate bonds are classified as held-to-maturity and are carried at amortized cost net of allowance for credit losses, which approximates their fair value determined based on Level 2 inputs. The restrictions on restricted cash and short-term investments have a negligible effect on the fair value of these financial assets. The fair value of the Company’s financial assets and liabilities measured on a recurring basis as of December 31, 2020 and 2019, are as follows: Total (Level 1) (Level 2) (Level 3) (in thousands) Cash equivalents - money market $ 58,710 $ 58,710 $ — $ — Restricted cash - money market 1,865 1,865 — — Short-term investments - certificates of deposit 9,089 — 9,089 — Restricted short-term investments - certificates of deposit 2,200 — 2,200 — Corporate bonds 1,307 — 1,307 — Interest rate swaps related to variable rate loans (902) — (902) — Fair value measurement as of December 31, 2020 $ 72,269 $ 60,575 $ 11,694 $ — Cash equivalents - money market $ 29,521 $ 29,521 $ — $ — Restricted cash - money market 1,865 1,865 — — Short-term investments - certificates of deposit 8,867 — 8,867 — Restricted short-term investments - certificates of deposit 2,290 — 2,290 — Corporate bonds 2,789 — 2,789 — Interest rate swaps related to variable rate loans (364) — (364) — Fair value measurement as of December 31, 2019 $ 44,968 $ 31,386 $ 13,582 $ — The Company does not hold any Level 3 instruments that are measured at fair value on a recurring basis. Nonfinancial assets and liabilities are not measured at fair value on a recurring basis but are subject to fair value adjustments in certain circumstances. These items primarily include long-lived assets, goodwill, and intangible assets for which the fair value of assets is determined as part of the related impairment test. As of December 31, 2020 and 2019, there were no significant adjustments to fair value for nonfinancial assets or liabilities.

Investments

Investments	12 Months Ended
Investments	Dec. 31, 2020
Investments
Investments	Note 9. Investments A summary of the Company’s investments that are classified as held-to-maturity are as follows: Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (in thousands) Corporate bonds $ 1,307 $ — $ — $ 1,307 Total investments as of December 31, 2020 $ 1,307 $ — $ — $ 1,307 Corporate bonds $ 2,790 $ — $ (1) $ 2,789 Total investments as of December 31, 2019 $ 2,790 $ — $ (1) $ 2,789 The Company believes that the unrealized gains and losses disclosed above were primarily driven by interest rate change rather than by unfavorable changes in the credit ratings associated with these securities and as a result, the Company continues to expect to collect the principal and interest due on its debt securities that have an amortized cost in excess of fair value. At each reporting period, the Company evaluates securities for impairment when the fair value of the investment is less than its amortized cost. The Company evaluated the underlying credit quality and credit ratings of the issuers, noting neither a significant deterioration since purchase nor any other factors that would indicate a material credit loss. The Company measures expected credit losses on held-to-maturity investments on a collective basis. All the Company’s held-to-maturity investments were considered to be one pool. The estimate for credit losses considers historical loss information that is adjusted for current conditions and reasonable and supportable forecasts. Expected credit losses on held-to-maturity investments were not material to the consolidated financial statements.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
Goodwill and Intangible Assets	Dec. 31, 2020
Goodwill and Intangible Assets
Goodwill and Intangible Assets	Note 10. Goodwill and Intangible Assets The table below shows the weighted-average life, original cost, accumulated amortization, and net book value by major intangible asset classification: Weighted-Average Accumulated Life (Years) Original Cost Amortization Net Book Value (in thousands) Definite-lived intangible assets IMS (UK) international product rights 10 $ 9,561 $ 4,223 $ 5,338 Patents 12 486 297 189 Land-use rights 39 2,540 617 1,923 Subtotal 12 12,587 5,137 7,450 Indefinite-lived intangible assets Trademark * 29,225 — 29,225 Goodwill - Finished pharmaceutical products * 3,940 — 3,940 Subtotal * 33,165 — 33,165 As of December 31, 2020 * $ 45,752 $ 5,137 $ 40,615 Weighted-Average Accumulated Life (Years) Original Cost Amortization Net Book Value (in thousands) Definite-lived intangible assets IMS (UK) international product rights 10 $ 9,226 $ 3,152 $ 6,074 Patents 12 486 255 231 Land-use rights 39 2,540 551 1,989 Other intangible assets 4 69 69 — Subtotal 12 12,321 4,027 8,294 Indefinite-lived intangible assets Trademark * 29,225 — 29,225 Goodwill - Finished pharmaceutical products * 3,634 — 3,634 Subtotal * 32,859 — 32,859 As of December 31, 2019 * $ 45,180 $ 4,027 $ 41,153 * Intangible assets with indefinite lives have an indeterminable average life. Sale of Fourteen Injectable ANDAs In February 2017, the Company sold the 14 ANDAs it acquired in March 2016 from Hikma to an unrelated party. The consideration included a purchase price of $6.4 million of which $1.0 million was received upon closing, $1.0 million was received in the second quarter of 2017 and the remaining $4.4 million was received in January 2018. In addition to the purchase price, the purchaser agreed to pay the Company a royalty fee equal to 2% of net sales derived from purchaser’s sales of the products for the period from February 2017 through February 2027. The Company has not recognized any royalty fee revenue. Goodwill The changes in the carrying amounts of goodwill were as follows: December 31, 2020 2019 (in thousands) Beginning balance $ 3,634 $ 3,951 Currency translation 306 (317) Ending balance $ 3,940 $ 3,634 Primatene ® Trademark In January 2009, the Company acquired the exclusive rights to the trademark, domain name, website and domestic marketing, distribution and selling rights related to Primatene Mist ® The trademark was determined to have an indefinite life. In determining its indefinite life, the Company considered the following: the expected use of the intangible; the longevity of the brand; the legal, regulatory and contractual provisions that affect their maximum useful life; the Company’s ability to renew or extend the asset’s legal or contractual life without substantial costs; effects of the regulatory environment; expected changes in distribution channels; maintenance expenditures required to obtain the expected future cash flows from the asset; and considerations for obsolescence, demand, competition and other economic factors. As a result of environmental concerns about chlorofluorocarbons, or CFCs, the FDA required the CFC formulation of Primatene Mist ® In 2013, the Company filed a new drug application, or NDA, for Primatene Mist ® ® Amortization Included in cost of revenues for the years ended December 31, 2020, 2019 and 2018 is product rights amortization expense of $1.2 million, $1.0 million, and $1.8 million, respectively. As of December 31, 2020, the expected amortization expense for all amortizable intangible assets during the next five fiscal years ended December 31 and thereafter is as follows: (in thousands) 2021 $ 1,064 2022 1,045 2023 1,035 2024 1,035 2025 1,035 Thereafter 2,236 Total amortizable intangible assets 7,450 Indefinite-lived intangibles 33,165 Total intangibles (net of accumulated amortization) $ 40,615

Inventories

Inventories	12 Months Ended
Inventories	Dec. 31, 2020
Inventories
Inventories	Note 11. Inventories Inventories consist of the following: December 31, 2020 2019 (in thousands) Raw materials and supplies $ 47,051 $ 59,233 Work in process 37,257 35,548 Finished goods 12,523 15,720 Total inventories $ 96,831 $ 110,501 Charges of $13.9 million, $9.4 million, and $12.9 million were included in the cost of revenues in the Company’s consolidated statements of operations for the years ended December 31, 2020, 2019, and 2018, respectively, to adjust the Company’s inventory and related purchase commitments to their net realizable value. For the year ended December 31, 2020, the charge included $9.4 million as a result of an increase in the price of heparin as well as a decrease in the forecasted average selling price. For the year ended December 31, 2019, the charge included $5.8 million as a result of an increase in purchases of higher price heparin. For the year ended December 31, 2018, the charge included $9.1 million related to enoxaparin inventory due to a decrease in the forecasted average selling price. Losses on firm purchase commitments related to raw materials on order were $1.2 million, $1.3 million and $5.2 million as of December 31, 2020, 2019 and 2018, respectively.

Property, Plant, and Equipment

Property, Plant, and Equipment	12 Months Ended
Property, Plant, and Equipment	Dec. 31, 2020
Property, Plant, and Equipment
Property, Plant, and Equipment	Note 12. Property, Plant, and Equipment Property, plant, and equipment consist of the following: December 31, 2020 2019 (in thousands) Buildings $ 124,326 $ 117,928 Leasehold improvements 30,028 29,531 Land 7,719 7,603 Machinery and equipment 211,666 164,802 Furniture, fixtures, and automobiles 26,482 22,043 Construction in progress 43,981 56,354 Total property, plant, and equipment 444,202 398,261 Less accumulated depreciation (184,147) (164,405) Total property, plant, and equipment, net $ 260,055 $ 233,856 The Company incurred depreciation expense of $20.5 million, $17.1 million, and $14.5 million for the years ended December 31, 2020, 2019, and 2018, respectively. Interest expense capitalized was approximately $1.8 million, $2.3 million, and $2.2 million, for the years ended December 31, 2020, 2019, and 2018, respectively.

Accounts Payable and Accrued Li

Accounts Payable and Accrued Liabilities	12 Months Ended
Accounts Payable and Accrued Liabilities	Dec. 31, 2020
Accounts Payable and Accrued Liabilities.
Accounts Payable and Accrued Liabilities	Note 13. Accounts Payable and Accrued Liabilities Accounts payable and accrued liabilities consisted of the following: December 31, 2020 2019 (in thousands) Accrued customer fees and rebates $ 9,029 $ 9,633 Accrued payroll and related benefits 24,597 21,872 Accrued product returns, current portion 10,190 7,126 Accrued loss on firm purchase commitments 1,223 3,352 Accrued litigation settlements 13,780 — Other accrued liabilities 12,328 10,007 Total accrued liabilities 71,147 51,990 Accounts payable 24,357 25,061 Total accounts payable and accrued liabilities $ 95,504 $ 77,051

Debt

Debt	12 Months Ended
Debt	Dec. 31, 2020
Debt
Debt	Note 14. Debt Debt consists of the following: December 31, 2020 2019 (in thousands) Line of Credit Facilities Line of credit facility with China Everbright Bank due June 2021 $ 764 $ — Line of credit facility with China Merchant Bank due August 2021 382 — Line of credit facility with Bank of Nanjing due October 2021 153 — Line of credit facility with Cathay Bank due May 2022 — — Line of credit facility with East West Bank due December 2022 — — Equipment line of credit facility with East West Bank due September 2025 3,216 — Mortgage Loans Mortgage payable with East West Bank due May 2021 3,306 3,401 Mortgage payable with East West Bank due October 2026 3,334 3,400 Mortgage payable with East West Bank due June 2027 8,510 8,659 Mortgage payable with Cathay Bank due August 2027 7,268 7,452 Equipment Loans Equipment loan with East West Bank due June 2021 612 1,837 Equipment loan due with East West Bank December 2022 4,000 6,000 Equipment loan with East West Bank due February 2024 5,254 3,570 Other Loans and Payment Obligations Acquisition loan with Cathay Bank due June 2024 8,710 10,928 French government loan paid off June 2020 — 28 French government loan due July 2021 64 114 French government loans due December 2026 350 374 Payment Obligation to Merck — 561 Equipment under Finance Leases 526 811 Total debt 46,449 47,135 Less current portion of long-term debt 12,263 7,741 Long-term debt, net of current portion $ 34,186 $ 39,394 Line of Credit Facilities Line of Credit Facility with China Everbright Bank – Due June 2021 In June 2020, the Company entered into a line of credit facility with China Everbright bank for $0.7 million. The loan bears interest at a fixed rate of 4.05%. Interest payments are due quarterly and repayment of the principle amount is due in June 2021. As of December 31, 2020, the Company had $0.8 million outstanding under this loan. Line of Credit Facility with China Merchant Bank – Due August 2021 In March 2020, the Company entered into a credit agreement with China Merchant Bank. The credit agreement allows the Company to borrow up to $14.6 million secured by buildings and land use rights held by ANP. The interest rate and other terms will be determined at the time of the borrowing, depending on the type of loan requested. The credit period is for 36 months and expires in March 2023. In August 2020, the Company borrowed $0.4 million under the credit agreement. The loan bears interest at a fixed rate of 4.35%. Interest payments are due quarterly and repayment of the principle amount is due in August 2021. As of December 31, 2020, the Company had $0.4 million outstanding under this loan. Line of Credit Facility with Bank of Nanjing – Due October 2021 In October 2020, the Company entered into a line of credit facility with Bank of Nanjing for $0.2 million. The loan bears interest at a fixed rate of 4.6%. Interest payments are due monthly and repayment of the principle amount is due in October 2021. As of December 31, 2020, the Company had $0.2 million outstanding under this loan. Line of Credit Facility with Cathay Bank — Due May 2022 In April 2012, the Company entered into a $20.0 million revolving line of credit facility with Cathay Bank. Borrowings under the facility are secured by inventory, accounts receivable, and intangibles held by the Company. The facility bears a variable interest rate at the prime rate as published by The Wall Street Journal with a minimum interest rate of 4.00% . In June 2020, the Company amended the facility to extend the maturity date from May 2020 to May 2022. As of December 31, 2020, the Company did not have any amounts outstanding under this facility. Line of Credit Facility with East West Bank — Due December 2022 In March 2012, the Company entered into a $10.0 million line of credit The Wall Street Journal In December 2020, the Company amended the facility to extend the maturity date to December 2022. As of December 31, 2020, the Company did not have any amounts outstanding Equipment Line of Credit with East West Bank — Due September 2025 In September 2020, the Company entered into a $10.0 million equipment credit line with a 12-month draw down period with East West Bank. Interest payments are due monthly through September 2021 at the prime rate as published by The Wall Street Journal The Wall Street Journal Mortgage Loans Mortgage Payable with East West Bank — Due May 2021 The Company refinanced the mortgage term loan with East West Bank in January 2016, which had an outstanding principal balance of $3.7 million at December 31, 2015, and had a maturity date of February 2021. The refinanced loan is payable in monthly installments with a final balloon payment of $3.3 million. The refinanced loan is secured by one of the buildings at the Company’s Rancho Cucamonga, California, headquarters complex. The refinanced loan has a variable interest rate at the prime rate as published by The Wall Street Journal In December 2020, the Company extended the maturity date to May 2021, with no changes to the monthly principle payments during the extension. The Company treated the extension as a modification for accounting purposes. Mortgage Payable with East West Bank — Due October 2026 In September 2006, the Company entered into a mortgage term loan with East West Bank in the principal amount of $2.8 million, which matured in September 2016. The Company refinanced the mortgage term loan in September 2016, which increased the principal amount to $3.6 million and extended the maturity date to October 2026. The refinanced loan is payable in monthly installments with a final balloon payment of $2.9 million. The refinanced loan was secured by one of the buildings at the Company’s Rancho Cucamonga, California, headquarters complex. The refinanced loan bears a variable interest rate at the one-month LIBOR rate plus 2.75%. As of December 31, 2020, the fair value of the loan approximates its book value. The interest rate used in the fair value estimation was determined to be a Level 2 input. Subsequently, the Company entered into a fixed interest rate swap contract on this loan to exchange the variable interest rate for a fixed interest rate of 4.15% until October 2021 without the exchange of the underlying notional debt amount. Mortgage Payable with East West Bank — Due June 2027 In May 2017, the Company entered into a mortgage term loan with East West Bank in the principal amount of $9.0 million, which matures in June 2027. The loan is payable in monthly installments with a final balloon payment of $7.4 million plus interest. The loan is secured by one of the buildings at the Company’s Rancho Cucamonga, California, headquarters complex and two buildings at the Company’s Chino, California, facility. The loan bears a variable interest rate at the one-month LIBOR rate plus 2.5%. As of December 31, 2020, the fair value of the loan approximates its book value. The interest rate used in the fair value estimation was determined to be a Level 2 input. The Company entered into a fixed interest rate swap contract on this loan to exchange the variable interest rate for a fixed interest rate of 4.79% until June 2024 without the exchange of the underlying notional debt amount. Mortgage Payable with Cathay Bank — Due August 2027 In August 2017, the Company refinanced the mortgage term loan with Cathay Bank that had been entered into on April 2014, with a principal balance outstanding of $7.9 million. The loan is payable in monthly installments and is secured by the building at the Company’s Canton, Massachusetts location. The loan bears interest at a fixed rate of 4.70% for the first five years of the loan; thereafter, the loan bears a variable interest rate at the prime rate as published by The Wall Street Journal and matures in June 2027. As of December 31, 2020, the fair value of the loan approximates its book value. The interest rate used in the fair value estimation was determined to be a Level 2 input. Equipment Loans Equipment Loan with East West Bank – Due June 2021 In March 2016, the Company entered into a $5.0 million equipment credit facility with East West Bank. In May 2017, the Company converted the outstanding balance of $5.0 million into a term equipment loan that matures in June 2021. Borrowings under the loan are secured by equipment. The loan bears a variable interest rate at the prime rate as published by The Wall Street Journal over the life of the facility without the exchange of the underlying notional debt amount. Equipment Loan with East West Bank — Due December 2022 In June 2017, the Company entered into an $8.0 million equipment credit line with an 18 -month draw down period with East West Bank. Interest payments are due monthly through December 2018 at the prime rate as published by The Wall Street Journal . After the draw down period, the outstanding principal balance converts into a 48 -month term loan which bears a variable interest rate at the prime rate as published by The Wall Street Journal . The loan matures in December 2022, and the principal and interest payments are due monthly. Borrowings under the facility are secured by equipment. In June 2018, the Company drew down $8.0 million on the equipment credit line and in December 2018, the credit line converted into an equipment loan. As of December 31, 2020, the fair value of the loan approximates its book value. The interest rate used in the fair value estimation was determined to be a Level 2 input. The Company entered into a fixed interest rate swap contract on this facility to exchange the variable interest rate for a fixed interest rate of 5.87% over the life of the facility without the exchange of the underlying notional debt amount. Equipment loan with East West Bank — Due February 2024 In January 2019, the Company entered into a $10.0 million equipment credit line with East West Bank which has a 12 -month draw down period. Interest payments are due monthly through February 2020 at the prime rate as published by The Wall Street Journal minus 1% . After the draw down period, the outstanding principal balance converts into a 48 -month term loan which bears a variable interest rate at the prime rate as published by The Wall Street Journal minus 1% . The loan matures in February 2024, and the principal and interest payments are due monthly. Borrowings under the facility are secured by equipment. As of December 31, 2019, the Company has drawn $3.6 million from the equipment line of credit. Subsequently, in January 2020, the Company drew an additional $3.0 million on the equipment credit line and in February 2020, the credit line converted into a $6.6 million equipment loan. As of December 31, 2020, the fair value of the loan approximates its book value. The Company entered into a fixed interest rate swap contract on this facility to exchange the variable interest rate for a fixed interest rate of 3.85% over the life of the facility without the exchange of the underlying notional debt amount. Other Loans and Payment Obligations Acquisition Loan with Cathay Bank — Due June 2024 On April 22, 2014, in conjunction with the Merck API Transaction, the Company entered into a secured term loan with Cathay Bank as lender. The principal amount of the loan was $21.9 million and had a variable interest rate at the prime rate as published by The Wall Street Journal In July 2019, the Company amended the acquisition loan relating to the AFP acquisition. The amendment was effective in June 2019. Under the amended loan agreement, the maturity date was extended to June 2024. The acquisition loan bears a variable interest rate at the prime rate as published by The Wall Street Journal The loan includes customary restrictions on, among other things, the Company’s ability to incur additional indebtedness, pay dividends in cash or make other distributions in cash, make certain investments, create liens, sell assets, and make loans. The loan also includes customary events of defaults, the occurrence and continuation of any of which provide Cathay Bank the right to exercise remedies against the Company and the collateral securing the loan. These events of default include, among other things, the Company’s failure to pay any amounts due under the loan, the Company’s insolvency, the occurrence of any default under certain other indebtedness or material agreements, and a final judgment against the Company that is not discharged in 30 days. Loans with Seine-Normandie Water Agency In January 2015, the Company entered into three French government loans with the Seine-Normandie water agency in the aggregate amount of $0.7 million. The loans have maturities that range between three to six years , include annual equal payments and bears no interest. In December 2018, the Company entered into two additional French government loans with the Seine-Normandie water agency in the aggregate amount $0.5 million. The loans have 8 year lives, and include annual equal payments and bear no interest. As of December 31, 2020, the payment obligation had an aggregate book value of $0.4 million, which approximates fair value. The fair value of the payment obligation was determined by using the interest rate associated with the Company’s acquisition loan with Cathay Bank that bears a variable interest rate at the prime rate as published by The Wall Street Journal Payment Obligation to Merck On April 30, 2014, in conjunction with the Company’s acquisition of Merck Sharpe & Dohme’s, API manufacturing business in Éragny-sur-Epte, France, or the Merck API Transaction, the Company entered into a commitment obligation with Merck, in the principal amount of $16.0 million. The terms of the purchase price include annual payments over four years and beard a fixed interest rate of 3.00%. In February 2020, the Company repaid all outstanding amounts due under this obligation. Covenants At December 31, 2020 and 2019, the Company was in compliance with its debt covenants. Long-Term Debt Maturities As of December 31, 2020, the principal amounts of long-term debt maturities during each of the next five fiscal years ending December 31 are as follows: Long-term Debt (in thousands) 2021 $ 11,950 2022 7,450 2023 5,666 2024 3,069 2025 1,273 Thereafter 16,515 $ 45,923

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2020
Income Taxes
Income Taxes	Note 15. Income Taxes The Company’s income (loss) before income taxes generated from its United States and foreign operations were: Year Ended December 31, 2020 2019 2018 (in thousands) Income (loss) before income taxes: United States $ 15,634 $ 77,092 $ 3,580 Foreign (10,997) (16,864) (13,506) Total income (loss) before taxes $ 4,637 $ 60,228 $ (9,926) The Company’s provision (benefit) for income taxes consisted of the following: Year Ended December 31, 2020 2019 2018 (in thousands) Current provision: Federal $ 1,803 $ 4,283 $ 32 State 541 430 343 Foreign 279 1,514 773 Total current provision 2,623 6,227 1,148 Deferred provision (benefit): Federal 1,770 9,825 (687) State (1,489) 499 (3,900) Foreign 636 (2,828) 173 Total deferred provision (benefit) 917 7,496 (4,414) Total provision (benefit) for income taxes $ 3,540 $ 13,723 $ (3,266) A reconciliation of the statutory federal income tax rate to the Company’s effective tax rate is as follows: Year Ended December 31, 2020 2019 2018 Statutory federal income tax (benefit) 21.0 % 21.0 % 21.0 % State tax expense, net of federal tax benefit (16.2) 1.2 28.3 Foreign tax rate differences (20.1) 1.2 4.0 Foreign valuation allowance 89.5 2.5 (42.0) Research and development credits (65.1) (4.8) 28.0 Share-based compensation 18.7 (1.5) 5.1 Executive compensation 48.1 2.9 (12.4) Deferred tax remeasurement — — 1.0 Employee-related expenses 1.7 0.2 (0.4) Other (1.3) 0.1 0.3 Effective tax rate (benefit) 76.3 % 22.8 % 32.9 % The Company’s effective tax rate for 2020 increased in comparison to 2019 primarily due to differences in pre-tax income positions and the recording of a valuation allowance on Hanxin deferred tax assets. Deferred Tax Assets and Liabilities Deferred income taxes reflect the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes, tax credit carryforwards, and the tax effects of net operating loss carryforwards. The significant components of the Company’s deferred tax assets and liabilities are as follows: December 31, 2020 2019 (in thousands) Deferred tax assets: Research and development credits $ 18,531 $ 18,603 Net operating loss carryforward 16,187 10,782 Inventory capitalization and reserve 7,744 8,518 Share-based compensation 5,564 6,390 Operating leases 4,999 4,741 Accrued expenses 4,340 4,153 Accrued chargebacks 3,927 3,729 Product return allowance 3,798 2,835 Intangibles 2,124 2,124 Other 2,633 85 Total deferred tax assets 69,847 61,960 Deferred tax liabilities: Depreciation/amortization 13,735 11,528 Intangibles 7,298 6,743 Operating leases 4,808 4,571 Federal impact of state deferred taxes 3,987 3,674 Total deferred tax liabilities 29,828 26,516 Valuation allowance (15,780) (10,438) Net deferred tax assets $ 24,239 $ 25,006 Net Operating Loss Carryforwards and Tax Credits At December 31, 2020, the Company had approximately $1.6 million California net operating loss carryforwards, or NOL carryforwards, and no material U.S. federal or other state NOL carryforwards. The California NOL carryforwards begin to expire in 2032 . The Company had France, United Kingdom, and China foreign NOL carryforwards of approximately $55.6 million, $1.4 million, and $12.4 million, respectively. The France and United Kingdom NOL carryforward can be used annually with certain limitations and have an indefinite carryforward period while the China NOL carryforward begins to expire in 2024 . At December 31, 2020, the Company had federal and California research and development tax credit carryforwards of approximately $2.1 million and $21.9 million, respectively. The federal research and development tax credit begins to expire in 2041 The utilization of NOL and credit carryforwards and other tax attributes could be subject to an annual limitation under Sections 382 and 383 of the Internal Revenue Code of 1986, or the Code, whereby they could be limited in the event a cumulative change in ownership of more than 50% occurs within a three-year period as defined in the Code. Valuation Allowance In assessing the need for a valuation allowance, management considers whether it is more likely than not that some portion or all of the deferred tax assets will be realized. Ultimately, the realization of deferred tax assets depends on the existence of future taxable income. Management considers sources of taxable income such as income in prior carryback periods, future reversal of existing deferred taxable temporary differences, tax-planning strategies, and projected future taxable income. The Company continues to record a full valuation allowance on AFP’s net deferred income tax assets and will continue to do so until AFP generates sufficient taxable income to realize its deferred income tax assets. However, a tax benefit is included in the annual effective tax rate computation due to AFP reporting a year-to-date foreign exchange gain in other comprehensive income. As of December 31, 2020 and 2019, the Company had a full valuation allowance against the net deferred tax assets of AFP, which totaled $13.7 million and $10.4 million, respectively. For the year ended December 31, 2020, the Company also determined that Hanxin more likely than not would not realize the benefit of its deferred tax assets due to recent operating losses. Therefore, the Company recorded a full valuation allowance of $2.1 million against Hanxin’s deferred tax assets. Undistributed Earnings from Foreign Operations As of December 31, 2020 and 2019, deferred income taxes have not been provided for any undistributed earnings from foreign operations. The foreign subsidiaries have accumulated losses of approximately $51.6 million and $44.9 million, respectively, and as such there are no earnings in which to provide taxes. It is the Company’s plan not to repatriate future foreign earnings to the U.S. and indefinitely reinvest such earnings in the foreign jurisdiction. CARES Act On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act, or the CARES Act, was signed into law in the U.S. to provide certain relief as a result of the COVID-19 pandemic. In addition, governments around the world have enacted or implemented various forms of tax relief measures in response to the economic conditions in the wake of COVID-19. As of December 31, 2020, neither the CARES Act nor changes to income tax laws or regulations in other jurisdictions had a significant impact on the Company’s effective tax rate. Uncertain Income Tax Positions A reconciliation of the beginning and ending balances of unrecognized tax benefits is as follows: December 31, 2020 2019 2018 (in thousands) Balance at the beginning of the year $ 8,331 $ 6,994 $ 7,438 Deductions based on tax positions related to prior years — — (1,566) Additions based on tax positions related to the current year 1,815 1,382 1,304 Deductions based on tax audit settlement — (45) (126) Deductions based on statute of limitations (93) — (56) Balance at the end of the year $ 10,053 $ 8,331 $ 6,994 Included in the balance of unrecognized tax benefits as of December 31, 2020 and 2019, was $9.9 million and $8.1 million, respectively that represents the portion that would impact the effective income tax rate if recognized. During the year ended December 31, 2018, the Company reduced unrecognized tax benefits for tax positions related to prior years by $1.6 million and for tax audit settlement by $0.1 million as the result of a state tax audit resolution. The Company recognizes interest and penalties related to unrecognized tax benefits in its income tax provision. For the years ended December 31, 2020, 2019 and 2018, the Company accrued interest of approximately $0.2 million, $0.3 million and $0.1 million, respectively, related to its uncertain tax positions. The Company and/or one or more of its subsidiaries filed income tax returns in the U.S. federal jurisdiction and various U.S. states and foreign jurisdictions. In February 2018, the IRS completed an examination of the Company’s 2015 income tax return resulting in no changes to reported tax. In June 2018, the Franchise Tax Board completed an examination of the Company’s 2007, 2008, and 2009 tax return resulting in no material tax liability. As of December 31, 2020, the Company does not have a tax examination in progress for federal, state, or foreign jurisdictions. The Company is subject to income tax audit by tax authorities for tax years 2017 to 2019 for federal, 2016 to 2019 for states and 2010 to 2019 for foreign.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2020
Stockholders' Equity
Stockholders' Equity	Note 16. Stockholders' Equity Common and Preferred Stock The Company’s Certificate of Incorporation authorizes the Company to issue 300,000,000 shares of common stock, $0.0001 par value per share, and 20,000,000 shares of preferred stock, $0.0001 par value per share. As of December 31, 2020 and 2019, there were no shares of preferred stock issued or outstanding. Equity Plans As of December 31, 2020, the Company has two equity plans: the Amended and Restated 2015 Equity Incentive Plan, or 2015 Plan, and the 2014 Employee Stock Purchase Plan or ESPP. Prior to the adoption of these plans, the Company granted options pursuant to the Amended and Restated 2005 Equity Incentive Award Plan. Upon termination of the predecessor plans, the shares available for grant at the time of termination, and shares subsequently returned to the plans upon forfeiture or option termination, were transferred to the successor plan in effect at the time of share return. The Company issues new shares of common stock upon exercise of stock options, vesting of restricted stock units, or RSU, and settlement of ESPP, with the exception of the awards granted to employees at AFP, which are settled through re-issuance of the Company’s treasury shares. Amended and Restated 2015 Equity Incentive Plan In March 2015, the Board of Directors adopted the Company’s 2015 Equity Incentive Plan, or the 2015 Plan, which was approved by the Company’s stockholders in May 2015 and is set to expire in March 2025. The 2015 Plan is designed to meet the needs of a publicly traded company, including the requirements for granting “performance based compensation” under Section 162(m) of the Internal Revenue Code. The 2015 Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock, restricted stock units, stock appreciation rights, performance units, performance shares, and other stock or cash awards to employees of the Company and its subsidiaries, members of the Board of Directors and consultants. In November 2020, the Board of Directors approved the Amendment and Restated 2015 Equity Incentive Plan to provide that at least 95% of the shares awarded under the plan will be subject to a minimum vesting requirement of at least one year . The Company initially reserved 5,000,000 shares of common stock for issuance under the 2015 Plan. This number will be increased by the number of shares available for issuance under the Company’s prior equity incentive plans or arrangements that are not subject to options or other awards, plus the number of shares of common stock related to options or other awards granted under the Company’s prior equity incentive plans or arrangements that are repurchased, forfeited, expired, or cancelled on or after the effective date of the 2015 Plan. The 2015 Plan also contains an “evergreen provision” that allows for an annual increase in the number of shares available for issuance on January 1 of each year during the 10 year term of the 2015 Plan, beginning January 1, 2016. The annual increase in the number of shares shall be the lesser of (i) 3,000,000 shares, (ii) two and one-half percent ( 2.5% ) of the outstanding shares on the last day of the immediately preceding fiscal year, or (iii) such number of shares as determined by the Board of Directors. As of the effective date, there were 5,300,296 shares available for grant under the 2015 Plan. As of December 31, 2020, the Company reserved an aggregate of 6,386,666 shares of common stock for future issuance under the 2015 Plan. In January 2021, an additional 1,187,386 shares were reserved under the 2015 Plan pursuant to the evergreen provision. Amended and Restated 2005 Equity Incentive Award Plan The Amended and Restated 2005 Equity Incentive Award Plan, or 2005 Plan, provided for the grant of incentive stock options, or ISOs, nonqualified stock options, or NQSOs, restricted stock awards, restricted stock unit awards, stock appreciation rights, or SARs, dividend equivalents and stock payments to the Company’s employees, members of the Board of Directors and consultants. Stock options under the 2005 Plan were granted with a term of up to ten years and at prices no less than the fair market value of the Company’s common stock on the date of grant. To date, stock options granted to existing employees generally vest over three to five years and stock options granted to new employees vest over four years . Stock options granted to Board of Directors and consultants generally vested over one year . As of March 2015, consequent to the 2015 Plan becoming effective, awards were no longer granted under the 2005 Plan. 2014 Employee Stock Purchase Plan In June 2014, the Company adopted the ESPP in connection with its initial public offering. A total of 2,000,000 shares of common stock are reserved for issuance under this plan. The Company’s ESPP permits eligible employees to purchase common stock at a discount through payroll deductions during defined offering periods. Under the ESPP, the Company may specify offerings with durations of not more than 27 months, and may specify shorter purchase periods within each offering. Each offering will have one or more purchase dates on which shares of its common stock will be purchased for employees participating in the offering. An offering may be terminated under certain circumstances. The price at which the stock is purchased is equal to 85% of the lower of the fair market value of the common stock at the beginning of an offering period or on the date of purchase. As of December 31, 2020, the Company has issued 807,550 shares of common stock under the ESPP and 1,192,450 shares of its common stock remains available for issuance under the ESPP. For the year ended December 31, 2020, 2019, and 2018, the Company recorded ESPP expense of $0.8 million, $0.7 million, and $0.7 million, respectively. Share Buyback Program As of December 31, 2020, the Company’s Board of Directors have authorized a total of $140.0 million. The primary goal of the program is to offset dilution created by the Company’s equity compensation programs. The Company’s share buyback program is expected to continue for an indefinite period of time. Purchases are made through open market and private block transactions pursuant to Rule 10b5-1 plans, privately negotiated transactions or other means as determined by the Company’s management and in accordance with the requirements of the SEC. The timing and actual number of treasury share purchases will depend on a variety of factors including price, corporate and regulatory requirements, and other conditions. These treasury share purchases are accounted for under the cost method and are included as a component of treasury stock in the Company’s consolidated balance sheets. Pursuant to the Company’s share buyback program, the Company purchased 1,366,384 shares, 1,122,781 shares, and 1,414,924, shares of its common stock during the years ended December 31, 2020, 2019 and 2018, totaling $24.4 million, $22.3 million, and $25.0 million, respectively. Share-Based Award Activity and Balances (excluding the ANP Equity Plan) The Company accounts for share-based compensation payments in accordance with ASC 718, which requires measurement and recognition of compensation expense at fair value for all share-based payment awards made to employees and directors. Under these standards, the fair value of option awards and the option components of the ESPP awards are estimated at the grant date using the Black-Scholes option-pricing model. The fair value of RSUs is estimated at the grant date using the Company’s common share price. Prior to the adoption of ASU No. 2018-07, Improvements to Non-employees Share-Based Payment Accounting Options issued under the Company’s 2015 Plan and 2005 Plan, are granted at exercise prices equal to or greater than the fair value of the underlying common shares on the date of grant and vest based on continuous service. There have been no awards with performance conditions and no awards with market conditions. The options have a contractual term of five three five The significant assumptions used in the Black-Scholes option-pricing are as follows: ● Determination of Fair Value of the Underlying Common Stock. For options and ESPP awards granted, the fair value for its underlying common stock is determined using the closing price on the date of grant as reported on the Nasdaq Global Select Market, or Nasdaq. Following the listing of our common stock on Nasdaq, we use the closing stock price as reported on Nasdaq on the grant date for the fair value of its stock. ● Expected Volatility. Starting in 2020, the Company estimates its volatility based on the weighted-average historical volatility of its stock price since IPO. Prior to that, the Company had limited data regarding company-specific historical or implied volatility of its share price. Consequently, the Company estimated its volatility based on the weighted average historical volatility of its stock price since IPO and the stock price from a set of peer companies, since our shares did not have sufficient trading history. Management considered factors such as stage of life cycle, competitors, size, market capitalization and financial leverage in the selection of similar entities. ● Expected Term. The expected term represents the period of time in which the options granted are expected to be outstanding. The Company estimates the expected term of options with consideration of vesting date, contractual term, and historical experience for exercise and post-vesting employment or contractual termination behavior after its common stock has been publicly traded. The expected term of “plain vanilla” options is estimated based on the midpoint between the vesting date and the end of the contractual term under the simplified method permitted by the SEC implementation guidance. The weighted-average expected term of the Company’s options is approximately five years. ● Risk- Free Rate. The risk-free interest rate is selected based upon the implied yields in effect at the time of the option grant on U.S. Treasury zero-coupon issues with a term approximately equal to the expected life of the option being valued. ● Dividends. The Company does not anticipate paying cash dividends in the foreseeable future. Consequently, the Company uses an expected dividend yield rate of zero. The Company estimates forfeitures at the time of grant and revises those estimates in subsequent periods if actual experience differs from those estimates. For the years ended December 31, 2020, 2019 and 2018, the Company estimated an average overall forfeiture rate of approximately 5%, based on historical experience. Forfeiture rates are separately estimated for its (1) directors and officers, (2) management personnel and (3) other employees. Share-based compensation is recorded net of expected forfeitures. The Company periodically assesses the forfeiture rate and the amount of expense recognized based on estimated historical forfeitures as compared to actual forfeitures. Changes in estimates are recorded in the period they are identified. Tax benefits resulting from tax deductions in excess of the share-based compensation cost recognized (excess tax benefits) are recorded in the statements of cash flows as financing activities. The weighted-averages for key assumptions used in determining the fair value of options granted during the years ended December 31, 2020, 2019, and 2018 are as follows: Year Ended December 31, 2020 2019 2018 Average volatility 43.1 % 42.5 % 39.9 % Average risk-free interest rate 0.8 % 2.4 % 2.7 % Weighted-average expected life in years 5.7 5.7 5.7 Dividend yield rate — % — % — % Stock Options A summary of option activity under all plans for the year ended December 31, 2020, is presented below: Weighted-Average Weighted-Average Remaining Aggregate Exercise Contractual Intrinsic Options Price Term (Years) Value (1) (in thousands) Outstanding as of December 31, 2019 9,763,485 $ 15.26 Options granted 1,803,048 13.57 Options exercised (1,761,104) 13.96 Options cancelled (112,180) 16.42 Options expired (1,112,774) 16.45 Outstanding as of December 31, 2020 8,580,475 $ 15.00 5.20 $ 45,392 Exercisable as of December 31, 2020 5,754,823 $ 14.41 3.93 $ 33,548 (1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the Company’s common stock for those awards that have an exercise price below the estimated fair value at December 31, 2020. During the years ended December 31, 2020, 2019, and 2018, the Company recorded expense of $9.1 million, $8.1 million, and $8.2 million, respectively, related to stock options granted under all plans. Information relating to option grants and exercises is as follows: Year Ended December 31, 2020 2019 2018 (in thousands, except per share data) Weighted-average grant date fair value per option share $ 5.51 $ 8.48 $ 7.80 Intrinsic value of options exercised 9,169 7,718 7,372 Cash received from options exercised 24,357 7,761 11,753 Total fair value of the options vested during the year 9,978 7,613 7,972 A summary of the status of the Company’s non-vested options as of December 31, 2020, and changes during the year ended December 31, 2020, are presented below: Weighted-Average Grant Date Options Fair Value Non-vested as of December 31, 2019 2,747,133 $ 6.99 Options granted 1,803,048 5.51 Options vested (1,612,349) 6.19 Options forfeited (112,180) 7.09 Non-vested as of December 31, 2020 2,825,652 6.50 As of December 31, 2020, there was $11.2 million of total unrecognized compensation cost, net of forfeitures, related to non-vested stock option based compensation arrangements granted under all plans. The cost is expected to be recognized over a weighted-average period of 2.2 In April 2020, Jason Shandell resigned from his position as the Company’s President and General Counsel and as a member of the Company’s board of directors. In connection with his resignation, the Company and Mr. Shandell entered into a separation agreement. As part of the separation agreement, the Company agreed to accelerate 80% of his unvested stock options and extended the expiration date of certain vested stock option awards. As a result of this modification, the Company incurred share-based compensation expense of $0.7 million, which is included within general and administration expenses in the consolidated statement of operations for the year ended December 31, 2020. Restricted Stock Units The Company grants restricted stock units, or RSUs, to certain employees and members of the Board of Directors with a vesting period of up to five years. The grantee receives one share of common stock at a specified future date for each RSU awarded. The RSUs may not be sold or otherwise transferred until certificates of common stock have been issued, recorded, and delivered to the participant. The RSUs do not have any voting or dividend rights prior to the issuance of certificates of the underlying common stock. The share-based expense associated with these grants was based on the Company’s common stock fair value at the time of grant and is amortized over the requisite service period, which generally is the vesting period, using the straight-line method. During the years ended December 31, 2020, 2019, and 2018, the Company recorded expenses of $10.0 million, $8.2 million, and $7.7 million, respectively, related to RSU awards granted under all plans. As part of the separation agreement with Mr. Shandell, the Company agreed to accelerate the vesting of 80% of his RSU awards. As a result of this modification, the Company incurred share-based compensation expense of $1.6 million, which is included within general and administrative expenses in the consolidated statement of operations for the year ended December 31, 2020. As of December 31, 2020, there was $12.0 million of total unrecognized compensation cost, net of forfeitures, related to non-vested RSU-based compensation arrangements granted under all plans. The cost is expected to be recognized over a weighted-average period of 2.2 years and will be adjusted for future changes in estimated forfeitures. Information relating to RSU grants and deliveries is as follows: Total Fair Market Value of RSUs Issued Total RSUs as Issued Compensation (1) (in thousands) RSUs outstanding at December 31, 2019 1,099,496 RSUs granted 733,566 $ 9,926 RSUs forfeited (48,490) RSUs vested (2) (628,054) RSUs outstanding at December 31, 2020 1,156,518 (1) The total FMV is derived from the number of RSUs granted times the current stock price on the date of grant. (2) Of the vested RSUs, 240,318 shares of common stock were surrendered to fulfil tax withholding obligations The 2018 ANP Equity Incentive Plan In December 2018, ANP’s board of directors approved the 2018 Plan, which is set to expire in December 2023. The 2018 Plan permits the grant of stock options and other equity awards in ANP shares to ANP employees. During the year ended December 31, 2020, ANP has granted 2,433,445 stock options to its employees under the 2018 Plan. In 2019, 3,648,932 stock options were granted to its employees under the 2018 Plan. As of December 31, 2020, the number of stock options outstanding was 5,709,977. The options vest over a period of approximately four years and have up to a 10 year contractual term. For the years ended December 31, 2020 and 2019, the Company recorded expense of $0.7 million and $0.3 million related to stock options issued by ANP under the 2018 Plan, respectively. Share-based Compensation Expense The Company recorded share-based compensation expense under all plans and is included in the Company’s consolidated statement of operations as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Cost of revenues $ 4,248 $ 3,819 $ 3,923 Operating expenses: Selling, distribution, and marketing 456 387 383 General and administrative 14,089 11,538 10,853 Research and development 1,705 1,551 1,521 Total share-based compensation $ 20,498 $ 17,295 $ 16,680

Employee Benefits

Employee Benefits	12 Months Ended
Employee Benefits	Dec. 31, 2020
Employee Benefits
Employee Benefits	Note 17. Employee Benefits 401(k) Plan The Company has a defined contribution 401(k) plan, or the Plan, whereby eligible employees voluntarily contribute up to a defined percentage of their annual compensation. The Company matches contributions at a rate of 50% on the first 6% of employee contributions, and pays the administrative costs of the Plan. Total employer contributions for the years ended December 31, 2020, 2019, and 2018 were approximately $1.9 million, $1.5 million, and $1.3 million, respectively. Defined Benefit Pension Plan The Company’s subsidiary, AFP, has an obligation associated with a defined-benefit plan for its eligible employees. This plan provides benefits to the employees from the date of retirement and is based on the employee’s length of time employed by the Company. The calculation is based on a statistical calculation combining a number of factors that include the employee’s age, length of service, and AFP employee turnover rate. The liability under the plan is based on a discount rate of 0.30% and 0.90% as of December 31, 2020 and 2019, respectively. The liability is included in accrued liabilities in the accompanying consolidated balance sheets. The plan is currently unfunded, and the benefit obligation under the plan was $3.0 million and $2.4 million at December 31, 2020 and 2019, respectively. Expense under the plan was $0.2 million, $0.2 million, and $0.3 million for the years ended December 31, 2020, 2019, and 2018, respectively. Gain or loss due to change in actuarial valuation of the Company’s defined benefit pension plan is recorded in other comprehensive income (loss). Deferred Compensation Plan In December 2019, the Company established a non-qualified deferred compensation plan. The deferred compensation plan allows certain eligible participants to defer a portion of their cash compensation and provides a matching contribution at the discretion of the Company. The plan obligations are payable upon retirement, termination of employment and/or certain other times in a lump-sum distribution or in installments, as elected by the participant in accordance with the plan. Participants can allocate their deferred compensation amongst various investment options with earnings accruing to the participant. The Company has established a Rabbi Trust to fund the plan obligations and to hold the plan assets. Eligible participants began contributing to the plan in January 2020. As of December 31, 2020, the plan assets and liabilities were valued at approximately $1.6 million and $1.7 million, respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2020
Commitments and Contingencies
Commitments and Contingencies	Note 18. Commitments and Contingencies Lease Liabilities On January 1, 2019, the Company adopted ASC 842, which resulted in the recognition of right-of-use, or ROU, assets of approximately $13.9 million and related lease liabilities of approximately $14.1 million in the consolidated balance sheet as of December 31, 2019, related to its operating lease commitments. ROU assets represent the Company’s right to control an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. Lease terms are generally based on their initial non-cancelable terms, unless there is a renewal option that is reasonably certain to be exercised. Various factors, including economic incentives, intent, past history and business needs are considered to determine if a renewal option is reasonably certain to be exercised. As most of its leases do not provide an implicit rate, the Company used its incremental borrowing rate based on the information available at the commencement date in determining the discount rate used to present value the lease payments. The Company has lease agreements with both lease and non-lease components, which are accounted for as a single component for all asset classes. The Company leases real and personal property, in the normal course of business, under various non-cancelable operating leases. The Company, at its option, can renew a substantial portion of its leases, at the market rate, for various renewal periods ranging from one to six years . The components of lease costs for the years ended December 31, 2020 and 2019 were as follows: Year Ended December 31, 2020 2019 (in thousands) Operating lease costs $ 4,462 $ 3,981 Short-term lease costs 649 613 Finance lease costs Amortization of right-of-use assets 351 351 Interest on lease liabilities 33 46 Total finance lease costs $ 384 $ 397 Total lease costs $ 5,495 $ 4,991 Other information pertaining to leases is as follows: Year Ended December 31, 2020 2019 (in thousands, except lease term and discount rate) Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 4,491 $ 3,531 Operating cash flows from finance leases 33 46 Financing cash flows from finance leases 369 354 Right-of use assets obtained in exchange for lease liabilities Operating leases 4,819 7,978 Finance leases 61 143 Weighted-average remaining lease term (years) Operating leases 8.7 8.1 Finance leases 2.3 2.8 Weighted-average discount rate Operating leases 5.2 % 5.9 % Finance leases 5.0 % 4.6 % Future minimum rental payments under leases that have initial or remaining non-cancelable lease terms in excess of 12 months as of December 31, 2020, are as follows: Operating Finance Leases Leases Total (in thousands) 2021 $ 4,362 $ 250 $ 4,612 2022 4,071 210 4,281 2023 2,819 50 2,869 2024 2,308 38 2,346 2025 1,976 18 1,994 Thereafter 10,691 — 10,691 Total lease payments $ 26,227 $ 566 $ 26,793 Less: interest 5,406 40 5,446 Total $ 20,821 $ 526 $ 21,347 Purchase Commitments As of December 31, 2020, the Company has entered into commitments to purchase equipment and raw materials for an aggregate amount of approximately $48.8 million. The Company anticipates that most of these commitments with a remaining term in excess of one year will be fulfilled by 2022. In accordance with certain agreements between ANP and the Chinese government, in January 2010 and November 2012, the Company acquired certain land-use rights for $1.2 million and $1.3 million, respectively. As required by these agreements, the Company was committed to spend approximately $15.0 million in the related land development, which primarily includes the construction of fixed assets according to a specific timetable. As of December 31, 2020, the Company has spent $19.5 million on such construction, fulfilling its commitment.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
Related-Party Transactions	Dec. 31, 2020
Related-Party Transactions
Related-Party Transactions	Note 19. Related-Party Transactions ANP Private Placement As discussed in footnote 2, in July 2018, ANP completed a private placement of its common equity interest and received approximately $56.3 million of cash proceeds. In connection with the private placement, all of the executive officers of the Company, Stephen Shohet, Howard Lee, and Richard Koo, directors of the Company, certain relatives of Dr. Jack Zhang and Dr. Mary Luo, and certain employees of ANP entered into subscription agreements (each, a “Subscription Agreement”) for the indirect investment in ANP. These Subscription Agreements were transacted either through an investment in Amphastar Cayman, a Cayman Islands limited liability company, or Qianqia or Zhongpan, Chinese partnerships. The aggregate gross proceeds received as of December 31, 2020, from such executive officers, directors and related parties were approximately $36.4 million. Retirement of James Luo In December 2020, James Luo retired from his position as the Company’s Senior Vice President of Engineering and President of AFP. Mr. Luo is a relative of the Company’s Chief Operating Officer, Dr. Mary Luo. In connection with his retirement, the Company and Mr. Luo entered into a retirement agreement where the Company agreed to pay Mr. Luo approximately $1.0 million in cash compensation over a period of three years as well as provide health insurance coverage for a six year period beginning in 2021. As a result, the Company recorded a total of $1.1 million in general and administrative expense in the fourth quarter of 2020 related to this agreement.

Litigation

Litigation	12 Months Ended
Litigation	Dec. 31, 2020
Litigation
Litigation	Note 20. Litigation Momenta/Sandoz Enoxaparin Patent and Antitrust Litigation In September 2011, Momenta Pharmaceuticals, Inc., or Momenta, a Boston based pharmaceutical company, and Sandoz Inc., or Sandoz, the generic division of Novartis, initiated litigation against the Company for alleged patent infringement of two patents related to testing methods for batch release of enoxaparin, which the Company refers to as the “’886 patent” and the “’466 patent.” On September 17, 2015, the Company initiated an antitrust lawsuit by filing a complaint in the California District Court against Momenta and Sandoz. This lawsuit was subsequently transferred to the Massachusetts District Court. On May 20, 2019, the Company and Momenta and Sandoz entered into a Settlement Agreement to settle the patent litigation and antitrust litigation. On June 27, 2019, Momenta and Sandoz paid the Company $59.9 million. The Company recorded the settlement amount as other income (expenses), in its consolidated statements of operations. Amphastar Pharmaceuticals, Inc. v Aventis Pharma, SA In January 2009, the Company filed a qui tam ® On May 11, 2017, the Company’s lawsuit against Aventis was dismissed for lack of jurisdiction. On July 14, 2017, Aventis filed an application with the District Court for entitlement to attorneys’ fees and expenses. On November 20, 2017, the District Court issued its order granting Aventis’ application for fees. On November 13, 2020, the Court issued an Opinion and Order (“Fee Order”) awarding Aventis $12.1 million in attorneys’ fees and $0.7 million in costs and expenses, and ordered Aventis to submit updated calculations on accrued interest. On December 14, 2020, Aventis submitted a supplemental application to the Court seeking interest for the time between the case’s inception and April 30, 2018, and fees, expenses, and interest for the period between May 1, 2018 and November 13, 2020. The Supplemental Application also identified a mathematical error in the Court’s Fee Order and requested that the Court revise the Fee Order to $12.2 million to correct the error. On December 14, 2020, the Company filed an appeal of the Fee Order to the United States Court of Appeals for the Ninth Circuit. On January 12, 2021, the Company submitted an opposition to the Supplemental Application identifying several issues with the Supplemental Application including Aventis’ incorrect calculation of fees based on the Fee Order, incorrect calculation of interest, among other procedural and factual arguments. The Court has not yet ruled on the Supplemental Application and has not provided a timeline by which the parties should expect a ruling. The Company has accrued $12.8 million relating to this litigation as of December 31, 2020 in other income (expenses) in the consolidated statement of operations. This amount represents management’s best estimate of the probable loss at this time. The final fee award could be higher and the final amount cannot be reasonably estimated at this time. The Company intends to continue to vigorously defend against any imposition of attorneys’ fees and expenses in this case. Regadenoson (0.4 mg/5 mL, 0.08 mg/mL) Patent Litigation On February 25, 2020, Astellas US LLC, Astellas Pharma US, Inc., and Gilead Sciences, Inc. (collectively, “Astellas-Gilead”) filed a Complaint in the United States District Court for the District of Delaware against IMS for infringement of U.S. Patent Nos. 8,106,183 (the “‘183 patent”), RE47,301 (the “‘301 patent”), and 8,524,883 (the “‘883 patent”) (collectively, “Astellas-Gilead Patents”) with regard to IMS’s ANDA No. 214,252 for approval to manufacture and sell 0.4 mg/5 mL (0.08 mg/mL) intravenous solution of Regadenoson. On March 4, 2020, IMS filed its Answer and Counterclaims. On March 30, 2020, the Court issued an Order allowing the Company to join pending consolidated litigation with five other generic Regadenoson ANDA filers involving similar claims. Trial is currently scheduled for June 14, 2021. The Company’s 30-month FDA stay expires August 10, 2022. The Company intends to vigorously defend this patent lawsuit. Employee Litigations Brenes v. International Medication Systems, Limited On September 11, 2019, a former employee, Raquel Brenes, (“Brenes”), initiated an employment litigation against IMS et al. by filing a Complaint in the Superior Court of California, Los Angeles County alleging individual and class action claims for alleged violations of various California labor laws pertaining to wage and hour, and other state laws. On September 18, 2019, Brenes filed a First Amended Complaint maintaining the individual and class action claims. On January 21, 2020, Brenes filed a Second Amended Complaint that alleges only Private Attorney General Act, or PAGA, claims and omitted the individual and class action claims. On February 9, 2021, the Company was able to successfully resolve these claims, as well as Brenes’ personal employment claims at mediation for $1.0 million. The agreement is still subject to approval by the court. The Company accrued the amount of $1.0 million as of December 31, 2020. Navarrette v. International Medication Systems, Limited On January 30, 2020, a former employee, Robert Navarrette, (“Navarrette”), provided written notice, through his counsel to IMS that he intends to file a PAGA lawsuit for alleged violations of various California labor laws pertaining to wage and hour. On April 7, 2020, Navarrete filed his PAGA lawsuit against IMS and Amphastar Pharmaceuticals, Inc. in the Superior Court of California, Los Angeles County, Central District. As to IMS, the Brenes Ramirez v. Amphastar Pharmaceuticals, Inc. On May 29, 2020, Priscilla Ramirez, (“Ramirez”), a former employee filed a PAGA lawsuit for alleged violations of various California labor laws pertaining to wage and hour against the Company. The parties have agreed to a mediation scheduled in April 2021. At this time, neither potential liability nor a reasonable and calculable estimate of exposure can be determined as initial evaluation is ongoing. The Company intends to vigorously defend this lawsuit. Other Litigation The Company is also subject to various other claims, arbitrations, and lawsuits from time to time arising in the ordinary course of business, including contractual employment matters. The Company records a provision for contingent losses when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. In the opinion of management, the ultimate resolution of any such matters is not expected to have a material adverse effect on its financial position, results of operations, or cash flows; however, the results of litigation and claims are inherently unpredictable and the Company’s view of these matters may change in the future. Regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources, and other factors.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2020
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company and its subsidiaries, and are prepared in accordance with United States generally accepted accounting principles, or GAAP. All intercompany activity has been eliminated in the preparation of the consolidated financial statements. In the opinion of management, the accompanying consolidated financial statements include all adjustments necessary to present fairly the consolidated financial position, results of operations, and cash flows of the Company. The Company’s subsidiaries include: (1) International Medication Systems, Limited, or IMS, (2) Armstrong Pharmaceuticals, Inc., or Armstrong, (3) Amphastar Nanjing Pharmaceuticals Inc., or ANP, (4) Nanjing Letop Biological Technology Co., Ltd., or Letop, (5) Nanjing Hanxin Pharmaceutical Technology Co., Ltd., or Hanxin, (6) Nanjing Hanxin Biomedical Testing Service Co., Ltd., or Hanxin Biomedical, (7) Nanjing Baixin Trading Co., Ltd., or Baixin, (8) Amphastar France Pharmaceuticals, S.A.S., or AFP, (9) Amphastar UK Ltd., or AUK, and (10) International Medication Systems (UK) Limited, or IMS UK. In July 2018, the Company’s Chinese subsidiary, ANP, completed a private placement of its common equity interest to accredited investors and received approximately $56.3 million of cash proceeds, a portion of which was received in 2019. The Company has retained approximately 58% of the equity interest in ANP following the private placement and continues to consolidate the financial results of ANP with the Company’s results of operations. ANP’s net income after July 2, 2018, was attributed to the Company in accordance with the Company’s equity interest of approximately 58% in ANP.
COVID-19 Pandemic	COVID-19 Pandemic The Company is subject to risks and uncertainties as a result of the novel coronavirus pandemic, or COVID-19. The complete extent of the impact of the COVID-19 pandemic on the Company’s business is highly uncertain and difficult to predict, as the information is constantly evolving. The Company considered the impact of COVID-19 on the assumptions and estimates used to determine the results reported and asset valuations as of December 31, 2020. In March 2020, the World Health Organization declared the outbreak of a novel coronavirus, or COVID-19, as a pandemic, which continues to spread throughout the world, including locations where the Company operates, such as the United States, China and France. The Company has been actively monitoring the COVID-19 pandemic and its impact globally. In late January 2020, China implemented extensive curfews and travel restrictions to control the outbreak, and started easing these restrictions in March. Our business operations in China experienced a temporary disruption but resumed full operation in February 2020. In March 2020, France also implemented a stay-at-home order limiting movement and restricting travel, however, the Company was deemed to be an essential business and was not significantly impacted by the restrictions. In March 2020, the Governors of the States of California and Massachusetts declared a health emergency and issued orders to close all nonessential business; as a bio-pharmaceutical company, the Company was deemed to be an essential businesses. Subsequently, some but not all of the restrictions were lifted in China, France, and states where the Company operates, and most businesses were allowed to reopen. All of the Company’s production facilities continued to operate during the remainder of the year as they had prior to the COVID-19 pandemic with very little change, other than for enhanced safety measures intended to prevent the spread of the virus. It is not possible at this time to estimate the complete impact that COVID-19 could have on the Company’s business, including its customers and suppliers, as the impact will depend on future developments, which are highly uncertain and cannot be predicted. Infections may resurge or become more widespread and the limitation on the Company’s ability to travel and timely sell and distribute its products, as well as any closures or supply disruptions, may be extended for longer periods of time, all of which would have a negative impact on the Company’s business, financial condition and operating results. The Company will continue to monitor the impact of COVID-19 on all aspects of its business.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. The principal accounting estimates include: determination of allowances for credit losses, allowance for discounts, provision for chargebacks and rebates, provision for product returns, adjustment of inventory to their net realizable values, impairment of long-lived and intangible assets and goodwill, workers’ compensation liabilities, litigation reserves, stock price volatilities for share-based compensation expense, valuation allowances for deferred tax assets, and liabilities for uncertain income tax positions.
Foreign Currency	Foreign Currency The functional currency of the Company, its domestic subsidiaries, its Chinese subsidiary ANP, and its U.K. subsidiary, AUK, is the USD. ANP maintains its books of record in Chinese yuan. These books are remeasured into the functional currency of USD using the current or historical exchange rates. The resulting currency remeasurement adjustments and other transactional foreign currency exchange gains and losses are reflected in the Company’s consolidated statements of operations. The Company’s French subsidiary, AFP, maintains its book of record in euros. ANP’s other Chinese subsidiaries, maintain their books of record in Chinese yuan. AUK’s subsidiary, IMS UK, maintains its book of record in British pounds. These local currencies have been determined to be the subsidiaries’ respective functional currencies. These books of record are translated into USD using average exchange rates during the period. Assets and liabilities are translated at the rate of exchange prevailing on the balance sheet date. Equity is translated at the prevailing rate of exchange at the date of the equity transactions. Translation adjustments are reflected in stockholders’ equity and are included as a component of other accumulated comprehensive income (loss). The unrealized gains or losses of intercompany foreign currency transactions that are of a long-term investment nature are reported in other accumulated comprehensive income (loss). The unrealized gains and losses of intercompany foreign currency transactions that are of a long-term investment nature for the years ended December 31, 2020, 2019, and 2018 were a $3.0 million gain, a $0.7 million loss, and a $1.5 million loss, respectively.
Comprehensive Income (Loss)	Comprehensive Income (Loss) For the years ended December 31, 2020, 2019 and 2018, the Company included its foreign currency translation gain (loss) and change in pension obligation of its defined benefit pension plan as part of its comprehensive income (loss) .
Shipping and Handling Costs	Shipping and Handling Costs For the years ended December 31, 2020, 2019, and 2018, the Company included shipping and handling costs of approximately $4.3 million, $4.3 million, and $3.7 million, respectively, in selling, distribution and marketing expenses in the accompanying consolidated statements of operations.
Advertising Expense	Advertising Expense Advertising expenses, primarily associated with Primatene Mist ®
Research and Development Costs	Research and Development Costs Research and development costs are charged to expense as incurred and consist of costs incurred to further the Company’s research and development activities. These include salaries and related employee benefits, costs associated with clinical trials, nonclinical research and development activities, regulatory activities, research-related overhead expenses and fees paid to external service providers. The Company may produce or purchase inventories prior to or with the expectation of receiving marketing authorization in the near term, based on operational decisions about the most effective use of existing resources. This inventory is referred to as pre-launch inventory. It is the Company’s accounting policy that the pre-launch inventory is capitalized if it has a probable future economic benefit. If marketing authorization is received and previously expensed pre-launch inventory is sold, such sales may contribute up to a 100% margin to the Company’s operating results. Pre-launch inventory costs include cost of work in process, materials, and finished drug products. As of December 31, 2020, 2019, and 2018, the Company did not have material capitalized pre-launch inventory.
Restricted Cash	Restricted Cash Restricted cash is collateral required for the Company to guarantee certain vendor payments in France. As of December 31, 2020 and 2019, the restricted cash balance was $1.9 million.
Restricted Short-Term Investments	Restricted Short-Term Investments Restricted short-term investments consist of certificates of deposit that are collateral for standby letters of credit to qualify for workers’ compensation self-insurance. The certificates of deposit have original maturities greater than three months, but less than one year. As of December 31, 2020 and 2019, the balance of restricted short-term investments was $2.2 million and $2.3 million, respectively.
Financial Instruments	Financial Instruments The carrying amounts of cash and cash equivalents, short-term investments, restricted cash and short-term investments, accounts receivable, accounts payable, accrued expenses, and short-term borrowings approximate fair value due to the short maturity of these items. The majority of the Company’s long-term obligations consist of variable rate debt, and their carrying value approximates fair value as the stated borrowing rates are comparable to rates currently offered to the Company for instruments with similar maturities. The Company at times enters into fixed interest rate swap contracts to exchange the variable interest rates for fixed interest rates without the exchange of the underlying notional debt amounts. Such interest rate swap contracts are recorded at their fair values.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash, money market accounts, certificates of deposit and highly liquid investments purchased with original maturities of three months or less.
Short-Term Investments	Short-Term Investments Short-term investments as of December 31, 2020 and 2019 consisted of certificates of deposit and investment grade corporate bonds with original expiration dates within 12 months.
Allowance for Credit Losses	Allowance for Credit Losses The Company evaluates the collectability of accounts receivable based on a combination of factors. When the Company is aware of circumstances that may impair a customer’s ability to pay subsequent to the original sale, the Company records a specific allowance to reduce the amounts receivable to the amount that the Company reasonably believes to be collectable. For all other customers, the Company recognizes an allowance for credit losses based on factors that include the length of time the receivables are past due, industry and geographic concentrations, the current economic conditions and historical collection experience. As of December 31, 2020 and 2019, the Company's allowance for credit losses was $1.3 million and $1.1 million, respectively.
Inventories	Inventories Inventories consist of currently marketed products and products manufactured under contract. Inventories are stated using the first-in, first-out method, on a consistent basis. The Company states inventory at the lower of cost and net realizable value. Provisions are made for slow-moving, unsellable, or obsolete items. Net realizable value is determined using the estimated selling price, in the ordinary course of business, less estimated costs to complete and dispose.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are stated at cost or, in the case of assets acquired in a business combination, at fair value on the purchase date. Depreciation and amortization expense is computed using the straight-line method over the estimated useful lives of the related assets as follows:
Intangible Assets	Intangible Assets Intangible assets with finite lives are amortized using the straight-line method over the period the asset is expected to contribute directly or indirectly to the future cash flows of the Company as follows:
Impairment of Long Lived Assets, including Identifiable Definite-Lived Intangible Assets	Impairment of Long-Lived Assets, including Identifiable Definite-Lived Intangible Assets The Company reviews long-term and identifiable definite-lived intangible assets or asset groups for impairment when events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable. If the sum of the expected future undiscounted cash flows is less than the carrying amount of the asset or an asset group, further impairment analysis is performed. An impairment loss is measured as the amount by which the carrying amount of the asset or asset groups exceeds the fair value (assets to be held and used) or fair value less cost to sell (assets to be disposed of). The Company also reviews the useful lives of its assets periodically to determine whether events and circumstances warrant a revision to the remaining useful life. Changes in the useful life are adjusted prospectively by revising the remaining period over which the asset is amortized.
Deferred Income Taxes	Deferred Income Taxes The Company utilizes the liability method of accounting for income taxes, under which deferred taxes are determined based on the temporary differences between the financial statements and the tax basis of assets and liabilities using enacted tax rates. A valuation allowance is recorded when it is more likely than not that the deferred tax assets will not be realized.
Impairment of Indefinite-Lived Intangible Asset and Goodwill
Self-Insured Claims	Self-Insured Claims The Company is primarily self-insured, up to certain limits, for workers’ compensation claims. The Company has purchased stop-loss insurance, which will reimburse the Company for individual claims in excess of $350,000 annually or aggregate claims exceeding $3.5 million annually. Operations are charged with the cost of claims reported and an estimate of claims incurred but not reported. A liability for unpaid claims and the associated claim expenses, including incurred but not reported losses, is actuarially determined and reflected in accrued liabilities in the accompanying consolidated balance sheets. Total expense under the program was approximately $0.5 million, $0.4 million, and $2.6 million, for the years ended December 31, 2020, 2019 and 2018, respectively. The self-insured claims liability was $4.5 million and $4.9 million at December 31, 2020 and 2019, respectively. The determination of such claims and expenses and the appropriateness of the related liability is reviewed periodically and updated, as necessary. Changes in estimates are recorded in the period identified.
Business Combinations	Business Combinations Business combinations are accounted for using the acquisition method of accounting, which requires an acquirer to recognize the assets acquired and the liabilities assumed at the acquisition date measured at their fair values as of that date. Fair value determinations are based on discounted cash flow analyses or other valuation techniques. In determining the fair value of the assets acquired and liabilities assumed in a material acquisition, the Company may utilize appraisals from third party valuation firms to determine fair values of some or all of the assets acquired and liabilities assumed, or may complete some or all of the valuations internally. In either case, the Company takes full responsibility for the determination of the fair value of the assets acquired and liabilities assumed. The value of goodwill reflects the excess of the fair value of the consideration conveyed to the seller over the fair value of the net assets received. Acquisition-related costs that the Company incurs to effect a business combination are expensed in the periods in which the costs are incurred. When the operations of the acquired businesses were not material to the Company’s consolidated financial statements, no pro forma presentations were disclosed.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update, or ASU, No. 2016-13 Financial Instruments – Credit Losses In January 2017, the FASB issued ASU No. 2017-04 Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU No. 2018-13 Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU No. 2018-14 Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans In August 2018, the FASB issued ASU No. 2018-15 Customer’s Accounting for Implementation Cost Incurred in a Cloud Computing Arrangement that is a Service Contract The adoption of the guidance did not have a material impact on the Company’s consolidated financial statements and related disclosures. In October 2018, the FASB issued ASU No. 2018-17 Targeted Improvements to Related Party Guidance for Variable Interest Entities In November 2018, the FASB issued ASU No. 2018-18 Clarifying the Interaction between Topic 808 and Topic 606 In December 2019, the FASB issued ASU No. 2019-12 Simplifying the Accounting for Income Taxes (Topic 740) In April 2020, the FASB issued ASU No. 2020-04 Reference Rate Reform (Topic 848), Facilitation of the Effects of Reference Rate Reform on Financial Reporting

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
Summary of Significant Accounting Policies (Tables)	Dec. 31, 2020
Summary of Significant Accounting Policies
Schedule of estimated useful life of property, plant and equipment	Buildings 20 - 31 years Machinery and equipment 3 - 12 years Furniture and fixtures 3 - 7 years Automobiles 4 - 5 years Leasehold improvements Lesser of remaining lease term or useful life
Schedule of estimated useful life of intangible assets	Product rights 10 - 15 years Patents 10 - 20 years Land-use rights 37 - 50 years

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
Revenue Recognition (Tables)	Dec. 31, 2020
Revenue Recognition
Schedule of chargeback and rebates provision analysis	Year Ended December 31, 2020 2019 (in thousands) Beginning balance $ 21,644 $ 22,423 Provision for chargebacks and rebates 158,152 131,524 Credits and payments issued to third parties (159,416) (132,303) Ending balance $ 20,380 $ 21,644
Schedule of product return liability analysis	Year Ended December 31, 2020 2019 (in thousands) Beginning balance $ 10,339 $ 8,030 Provision for product returns 11,810 7,305 Credits issued to third parties (7,945) (4,996) Ending balance $ 14,204 $ 10,339

Income (Loss) per Share Attri_2

Income (Loss) per Share Attributable to Amphastar Pharmaceuticals, Inc. Stockholders (Tables)	12 Months Ended
	Dec. 31, 2020
Income (Loss) per Share Attributable to Amphastar Pharmaceuticals, Inc. Stockholders
Schedule of basic and diluted net income (loss) per share calculation	Year Ended December 31, 2020 2019 2018 (in thousands, except per share data) Basic and dilutive numerator: Net income (loss) attributable to Amphastar Pharmaceuticals, Inc. $ 1,403 $ 48,939 $ (5,738) Denominator: Weighted-average shares outstanding — basic 47,038 46,982 46,395 Net effect of dilutive securities: Incremental shares from equity awards 2,086 2,925 — Weighted-average shares outstanding — diluted 49,124 49,907 46,395 Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. stockholders — basic $ 0.03 $ 1.04 $ (0.12) Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. stockholders — diluted $ 0.03 $ 0.98 $ (0.12)

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
Segment Reporting (Tables)	Dec. 31, 2020
Segment Reporting
Schedule of financial information by reporting segment	Year Ended December 31, 2020 2019 2018 (in thousands) Net revenues: Finished pharmaceutical products $ 331,368 $ 302,000 $ 271,059 API 18,478 20,357 23,607 Total net revenues 349,846 322,357 294,666 Gross profit (loss): Finished pharmaceutical products 151,645 136,576 113,220 API (8,305) (4,653) (6,235) Total gross profit 143,340 131,923 106,985 Operating expenses 132,386 131,962 115,608 Income from operations 10,954 (39) (8,623) Non-operating (expense) income (6,317) 60,267 (1,303) Income (loss) before income taxes $ 4,637 $ 60,228 $ (9,926)
Schedule of net revenues in the finished pharmaceutical products segment	Year Ended December 31, 2020 2019 2018 (in thousands) Finished pharmaceutical products net revenues: Primatene Mist ® $ 51,725 $ 18,065 $ 3,574 Enoxaparin 48,681 42,695 53,371 Phytonadione 42,646 45,786 41,897 Lidocaine 41,113 46,013 43,328 Naloxone 33,416 34,761 37,195 Epinephrine 23,799 13,885 10,055 Other finished pharmaceutical products 89,988 100,795 81,639 Total finished pharmaceutical products net revenues $ 331,368 $ 302,000 $ 271,059
Schedule of depreciation and amortization expense by reporting segment	Year Ended December 31, 2020 2019 2018 (in thousands) Depreciation and amortization expense Finished pharmaceutical products $ 5,766 $ 5,581 $ 4,872 API 3,264 1,477 1,181 Total depreciation and amortization expense $ 9,030 $ 7,058 $ 6,053
Schedule of net revenues and carrying values of long-lived assets by geographic region	Net Revenue Long-Lived Assets Year Ended December 31, December 31, 2020 2019 2018 2020 2019 (in thousands) United States $ 333,093 $ 304,896 $ 279,122 $ 129,401 $ 126,383 China 3,161 1,481 — 98,538 81,428 France 13,592 15,980 15,544 52,770 45,737 Total $ 349,846 $ 322,357 $ 294,666 $ 280,709 $ 253,548

Customer and Supplier Concent_2

Customer and Supplier Concentration (Tables)	12 Months Ended
Customer and Supplier Concentration (Tables)	Dec. 31, 2020
Customer and Supplier Concentration
Schedule of accounts receivable and net revenues by major customer	% of Total Accounts % of Net Receivable Revenue December 31, December 31, Year Ended December 31, 2020 2019 2020 2019 2018 AmerisourceBergen 9 % 13 % 23 % 24 % 27 % McKesson 24 % 34 % 22 % 25 % 27 % Cardinal Health 17 % 17 % 17 % 22 % 21 %

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2020
Fair Value Measurements
Schedule of financial assets and liabilities measured on a recurring basis	Total (Level 1) (Level 2) (Level 3) (in thousands) Cash equivalents - money market $ 58,710 $ 58,710 $ — $ — Restricted cash - money market 1,865 1,865 — — Short-term investments - certificates of deposit 9,089 — 9,089 — Restricted short-term investments - certificates of deposit 2,200 — 2,200 — Corporate bonds 1,307 — 1,307 — Interest rate swaps related to variable rate loans (902) — (902) — Fair value measurement as of December 31, 2020 $ 72,269 $ 60,575 $ 11,694 $ — Cash equivalents - money market $ 29,521 $ 29,521 $ — $ — Restricted cash - money market 1,865 1,865 — — Short-term investments - certificates of deposit 8,867 — 8,867 — Restricted short-term investments - certificates of deposit 2,290 — 2,290 — Corporate bonds 2,789 — 2,789 — Interest rate swaps related to variable rate loans (364) — (364) — Fair value measurement as of December 31, 2019 $ 44,968 $ 31,386 $ 13,582 $ —

Investments (Tables)

Investments (Tables)	12 Months Ended
Investments (Tables)	Dec. 31, 2020
Investments
Schedule of securities classified as held-to-maturity	Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (in thousands) Corporate bonds $ 1,307 $ — $ — $ 1,307 Total investments as of December 31, 2020 $ 1,307 $ — $ — $ 1,307 Corporate bonds $ 2,790 $ — $ (1) $ 2,789 Total investments as of December 31, 2019 $ 2,790 $ — $ (1) $ 2,789

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
Goodwill and Intangible Assets (Tables)	Dec. 31, 2020
Goodwill and Intangible Assets
Schedule of weighted-average life, original cost, accumulated amortization and net book value by major class	Weighted-Average Accumulated Life (Years) Original Cost Amortization Net Book Value (in thousands) Definite-lived intangible assets IMS (UK) international product rights 10 $ 9,561 $ 4,223 $ 5,338 Patents 12 486 297 189 Land-use rights 39 2,540 617 1,923 Subtotal 12 12,587 5,137 7,450 Indefinite-lived intangible assets Trademark * 29,225 — 29,225 Goodwill - Finished pharmaceutical products * 3,940 — 3,940 Subtotal * 33,165 — 33,165 As of December 31, 2020 * $ 45,752 $ 5,137 $ 40,615 Weighted-Average Accumulated Life (Years) Original Cost Amortization Net Book Value (in thousands) Definite-lived intangible assets IMS (UK) international product rights 10 $ 9,226 $ 3,152 $ 6,074 Patents 12 486 255 231 Land-use rights 39 2,540 551 1,989 Other intangible assets 4 69 69 — Subtotal 12 12,321 4,027 8,294 Indefinite-lived intangible assets Trademark * 29,225 — 29,225 Goodwill - Finished pharmaceutical products * 3,634 — 3,634 Subtotal * 32,859 — 32,859 As of December 31, 2019 * $ 45,180 $ 4,027 $ 41,153 * Intangible assets with indefinite lives have an indeterminable average life.
Schedule of changes in carrying amounts of goodwill	December 31, 2020 2019 (in thousands) Beginning balance $ 3,634 $ 3,951 Currency translation 306 (317) Ending balance $ 3,940 $ 3,634
Schedule of finite-lived intangible assets, future amortization expense	(in thousands) 2021 $ 1,064 2022 1,045 2023 1,035 2024 1,035 2025 1,035 Thereafter 2,236 Total amortizable intangible assets 7,450 Indefinite-lived intangibles 33,165 Total intangibles (net of accumulated amortization) $ 40,615

Inventories (Tables)

Inventories (Tables)	12 Months Ended
Inventories (Tables)	Dec. 31, 2020
Inventories
Schedule of inventories	December 31, 2020 2019 (in thousands) Raw materials and supplies $ 47,051 $ 59,233 Work in process 37,257 35,548 Finished goods 12,523 15,720 Total inventories $ 96,831 $ 110,501

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	12 Months Ended
Property, Plant, and Equipment (Tables)	Dec. 31, 2020
Property, Plant, and Equipment
Schedule of property, plant, and equipment	December 31, 2020 2019 (in thousands) Buildings $ 124,326 $ 117,928 Leasehold improvements 30,028 29,531 Land 7,719 7,603 Machinery and equipment 211,666 164,802 Furniture, fixtures, and automobiles 26,482 22,043 Construction in progress 43,981 56,354 Total property, plant, and equipment 444,202 398,261 Less accumulated depreciation (184,147) (164,405) Total property, plant, and equipment, net $ 260,055 $ 233,856

Accounts Payable and Accrued _2

Accounts Payable and Accrued Liabilities (Tables)	12 Months Ended
Accounts Payable and Accrued Liabilities (Tables)	Dec. 31, 2020
Accounts Payable and Accrued Liabilities.
Schedule of accounts payable and accrued liabilities	December 31, 2020 2019 (in thousands) Accrued customer fees and rebates $ 9,029 $ 9,633 Accrued payroll and related benefits 24,597 21,872 Accrued product returns, current portion 10,190 7,126 Accrued loss on firm purchase commitments 1,223 3,352 Accrued litigation settlements 13,780 — Other accrued liabilities 12,328 10,007 Total accrued liabilities 71,147 51,990 Accounts payable 24,357 25,061 Total accounts payable and accrued liabilities $ 95,504 $ 77,051

Debt (Tables)

Debt (Tables)	12 Months Ended
Debt (Tables)	Dec. 31, 2020
Debt
Schedule of debt	December 31, 2020 2019 (in thousands) Line of Credit Facilities Line of credit facility with China Everbright Bank due June 2021 $ 764 $ — Line of credit facility with China Merchant Bank due August 2021 382 — Line of credit facility with Bank of Nanjing due October 2021 153 — Line of credit facility with Cathay Bank due May 2022 — — Line of credit facility with East West Bank due December 2022 — — Equipment line of credit facility with East West Bank due September 2025 3,216 — Mortgage Loans Mortgage payable with East West Bank due May 2021 3,306 3,401 Mortgage payable with East West Bank due October 2026 3,334 3,400 Mortgage payable with East West Bank due June 2027 8,510 8,659 Mortgage payable with Cathay Bank due August 2027 7,268 7,452 Equipment Loans Equipment loan with East West Bank due June 2021 612 1,837 Equipment loan due with East West Bank December 2022 4,000 6,000 Equipment loan with East West Bank due February 2024 5,254 3,570 Other Loans and Payment Obligations Acquisition loan with Cathay Bank due June 2024 8,710 10,928 French government loan paid off June 2020 — 28 French government loan due July 2021 64 114 French government loans due December 2026 350 374 Payment Obligation to Merck — 561 Equipment under Finance Leases 526 811 Total debt 46,449 47,135 Less current portion of long-term debt 12,263 7,741 Long-term debt, net of current portion $ 34,186 $ 39,394
Schedule of Maturities of Long-term Debt	Long-term Debt (in thousands) 2021 $ 11,950 2022 7,450 2023 5,666 2024 3,069 2025 1,273 Thereafter 16,515 $ 45,923

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2020
Income Taxes
Schedule of income (loss) before income taxes	Year Ended December 31, 2020 2019 2018 (in thousands) Income (loss) before income taxes: United States $ 15,634 $ 77,092 $ 3,580 Foreign (10,997) (16,864) (13,506) Total income (loss) before taxes $ 4,637 $ 60,228 $ (9,926)
Summary of provision (benefit) for income taxes	Year Ended December 31, 2020 2019 2018 (in thousands) Current provision: Federal $ 1,803 $ 4,283 $ 32 State 541 430 343 Foreign 279 1,514 773 Total current provision 2,623 6,227 1,148 Deferred provision (benefit): Federal 1,770 9,825 (687) State (1,489) 499 (3,900) Foreign 636 (2,828) 173 Total deferred provision (benefit) 917 7,496 (4,414) Total provision (benefit) for income taxes $ 3,540 $ 13,723 $ (3,266)
Schedule of reconciliation of the statutory federal income tax rate	Year Ended December 31, 2020 2019 2018 Statutory federal income tax (benefit) 21.0 % 21.0 % 21.0 % State tax expense, net of federal tax benefit (16.2) 1.2 28.3 Foreign tax rate differences (20.1) 1.2 4.0 Foreign valuation allowance 89.5 2.5 (42.0) Research and development credits (65.1) (4.8) 28.0 Share-based compensation 18.7 (1.5) 5.1 Executive compensation 48.1 2.9 (12.4) Deferred tax remeasurement — — 1.0 Employee-related expenses 1.7 0.2 (0.4) Other (1.3) 0.1 0.3 Effective tax rate (benefit) 76.3 % 22.8 % 32.9 %
Summary of deferred tax assets and liabilities	December 31, 2020 2019 (in thousands) Deferred tax assets: Research and development credits $ 18,531 $ 18,603 Net operating loss carryforward 16,187 10,782 Inventory capitalization and reserve 7,744 8,518 Share-based compensation 5,564 6,390 Operating leases 4,999 4,741 Accrued expenses 4,340 4,153 Accrued chargebacks 3,927 3,729 Product return allowance 3,798 2,835 Intangibles 2,124 2,124 Other 2,633 85 Total deferred tax assets 69,847 61,960 Deferred tax liabilities: Depreciation/amortization 13,735 11,528 Intangibles 7,298 6,743 Operating leases 4,808 4,571 Federal impact of state deferred taxes 3,987 3,674 Total deferred tax liabilities 29,828 26,516 Valuation allowance (15,780) (10,438) Net deferred tax assets $ 24,239 $ 25,006
Schedule of unrecognized tax benefits	December 31, 2020 2019 2018 (in thousands) Balance at the beginning of the year $ 8,331 $ 6,994 $ 7,438 Deductions based on tax positions related to prior years — — (1,566) Additions based on tax positions related to the current year 1,815 1,382 1,304 Deductions based on tax audit settlement — (45) (126) Deductions based on statute of limitations (93) — (56) Balance at the end of the year $ 10,053 $ 8,331 $ 6,994

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
Stockholders' Equity (Tables)	Dec. 31, 2020
Stockholders' Equity
Schedule of key assumptions to determine fair value of options	Year Ended December 31, 2020 2019 2018 Average volatility 43.1 % 42.5 % 39.9 % Average risk-free interest rate 0.8 % 2.4 % 2.7 % Weighted-average expected life in years 5.7 5.7 5.7 Dividend yield rate — % — % — %
Schedule of the summary of option activity under all plans	Weighted-Average Weighted-Average Remaining Aggregate Exercise Contractual Intrinsic Options Price Term (Years) Value (1) (in thousands) Outstanding as of December 31, 2019 9,763,485 $ 15.26 Options granted 1,803,048 13.57 Options exercised (1,761,104) 13.96 Options cancelled (112,180) 16.42 Options expired (1,112,774) 16.45 Outstanding as of December 31, 2020 8,580,475 $ 15.00 5.20 $ 45,392 Exercisable as of December 31, 2020 5,754,823 $ 14.41 3.93 $ 33,548
Schedule of information relating to options grants	Year Ended December 31, 2020 2019 2018 (in thousands, except per share data) Weighted-average grant date fair value per option share $ 5.51 $ 8.48 $ 7.80 Intrinsic value of options exercised 9,169 7,718 7,372 Cash received from options exercised 24,357 7,761 11,753 Total fair value of the options vested during the year 9,978 7,613 7,972
Schedule of the summary of nonvested options status	Weighted-Average Grant Date Options Fair Value Non-vested as of December 31, 2019 2,747,133 $ 6.99 Options granted 1,803,048 5.51 Options vested (1,612,349) 6.19 Options forfeited (112,180) 7.09 Non-vested as of December 31, 2020 2,825,652 6.50
Schedule of information relating to RSU grants and deliveries	Total Fair Market Value of RSUs Issued Total RSUs as Issued Compensation (1) (in thousands) RSUs outstanding at December 31, 2019 1,099,496 RSUs granted 733,566 $ 9,926 RSUs forfeited (48,490) RSUs vested (2) (628,054) RSUs outstanding at December 31, 2020 1,156,518 (1) The total FMV is derived from the number of RSUs granted times the current stock price on the date of grant. (2) Of the vested RSUs, 240,318 shares of common stock were surrendered to fulfil tax withholding obligations
Schedule of recorded share-based compensation expense under all plans	Year Ended December 31, 2020 2019 2018 (in thousands) Cost of revenues $ 4,248 $ 3,819 $ 3,923 Operating expenses: Selling, distribution, and marketing 456 387 383 General and administrative 14,089 11,538 10,853 Research and development 1,705 1,551 1,521 Total share-based compensation $ 20,498 $ 17,295 $ 16,680

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
Commitments and Contingencies (Tables)	Dec. 31, 2020
Commitments and Contingencies
Schedule of lease information	The components of lease costs for the years ended December 31, 2020 and 2019 were as follows: Year Ended December 31, 2020 2019 (in thousands) Operating lease costs $ 4,462 $ 3,981 Short-term lease costs 649 613 Finance lease costs Amortization of right-of-use assets 351 351 Interest on lease liabilities 33 46 Total finance lease costs $ 384 $ 397 Total lease costs $ 5,495 $ 4,991 Other information pertaining to leases is as follows: Year Ended December 31, 2020 2019 (in thousands, except lease term and discount rate) Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 4,491 $ 3,531 Operating cash flows from finance leases 33 46 Financing cash flows from finance leases 369 354 Right-of use assets obtained in exchange for lease liabilities Operating leases 4,819 7,978 Finance leases 61 143 Weighted-average remaining lease term (years) Operating leases 8.7 8.1 Finance leases 2.3 2.8 Weighted-average discount rate Operating leases 5.2 % 5.9 % Finance leases 5.0 % 4.6 %
Schedule of future minimum rental payments for operating leases	Operating Finance Leases Leases Total (in thousands) 2021 $ 4,362 $ 250 $ 4,612 2022 4,071 210 4,281 2023 2,819 50 2,869 2024 2,308 38 2,346 2025 1,976 18 1,994 Thereafter 10,691 — 10,691 Total lease payments $ 26,227 $ 566 $ 26,793 Less: interest 5,406 40 5,446 Total $ 20,821 $ 526 $ 21,347

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details) - USD ($)	Jul. 02, 2018	Jul. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Proceeds from private placement				$ 18,298,000	$ 38,036,000
Gains and (losses) of intercompany foreign currency transactions			$ 3,000,000	(700,000)	(1,500,000)
Income tax expense allocated to other comprehensive income			900,000	0	0
Selling, distribution, and marketing expense			14,780,000	12,830,000	8,156,000
Allowance for Credit Losses			1,300,000	1,100,000
Restricted cash			1,865,000	1,865,000
Certificates of deposit			2,200,000	2,300,000
Amount retained, individual claims			350,000
Amount retained, aggregate claims			3,500,000
Actuarially Determined Self-insurance Expense			500,000	400,000	2,600,000
Self-insurance Claims Liability			4,500,000	4,900,000
ANP
Proceeds from private placement		$ 56,300,000
Proceeds from private placement		$ 56,300,000
Equity interest retained post private placement	58.00%
Finished Pharmaceutical Products \| Primatene Mist
Advertising expense			5,800,000	4,300,000	400,000
Shipping and Handling [Member]
Selling, distribution, and marketing expense			$ 4,300,000	$ 4,300,000	$ 3,700,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies (Schedule of PP&E Useful Lives) (Details)	12 Months Ended
	Dec. 31, 2020
Buildings \| Minimum
Property, Plant and Equipment
Property, Plant and Equipment Useful Life	20 years
Buildings \| Maximum
Property, Plant and Equipment
Property, Plant and Equipment Useful Life	31 years
Machinery and equipment \| Minimum
Property, Plant and Equipment
Property, Plant and Equipment Useful Life	3 years
Machinery and equipment \| Maximum
Property, Plant and Equipment
Property, Plant and Equipment Useful Life	12 years
Furniture and Fixtures \| Minimum
Property, Plant and Equipment
Property, Plant and Equipment Useful Life	3 years
Furniture and Fixtures \| Maximum
Property, Plant and Equipment
Property, Plant and Equipment Useful Life	7 years
Automobiles \| Minimum
Property, Plant and Equipment
Property, Plant and Equipment Useful Life	4 years
Automobiles \| Maximum
Property, Plant and Equipment
Property, Plant and Equipment Useful Life	5 years

Summary of Significant Accoun_6

Summary of Significant Accounting Policies (Schedule of Intangible Useful Lives) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Useful life of intangibles	12 years	12 years
Product rights \| Minimum
Useful life of intangibles	10 years
Product rights \| Maximum
Useful life of intangibles	15 years
Patents
Useful life of intangibles	12 years	12 years
Patents \| Minimum
Useful life of intangibles	10 years
Patents \| Maximum
Useful life of intangibles	20 years
Land-use rights
Useful life of intangibles	39 years	39 years
Land-use rights \| Minimum
Useful life of intangibles	37 years
Land-use rights \| Maximum
Useful life of intangibles	50 years

Business Acquisitions (Details)

Business Acquisitions (Details) $ in Millions	1 Months Ended	12 Months Ended
Business Acquisitions (Details) $ in Millions	Mar. 31, 2016USD ($)item	Dec. 31, 2020	Dec. 31, 2019
Business Acquisitions
Useful life of intangibles		12 years	12 years
Hikma Pharmaceuticals PLC
Business Acquisitions
Number of Different Injectable Chemical Entities \| item	11
Payment to Acquire Business, Gross \| $	$ 4
Useful life of intangibles	15 years
Number of Injectable Products Acquired \| item	14
Assets acquired \| $	$ 4

Revenue Recognition (Analysis o

Revenue Recognition (Analysis of the Chargeback Provision) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Beginning balance	$ 21,644	$ 22,423
Provision for chargebacks and rebates	158,152	131,524
Credits and payments issued to third parties	(159,416)	(132,303)
Ending balance	$ 20,380	21,644
Minimum
Payment terms	30 days
Settlement of chargebacks and rebates terms	30 days
Maximum
Payment terms	75 days
Settlement of chargebacks and rebates terms	60 days
Accounts Receivable, Net
Provision for chargebacks and rebates	$ 16,400	15,400
Accounts Payable and Accrued Liabilities
Provision for chargebacks and rebates	$ 4,000	$ 6,200

Revenue Recognition (Analysis_2

Revenue Recognition (Analysis of Product Return Liability) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Aggregate product return rate	1.40%	1.10%
Return accrual included in accounts payable and accrued liabilities	$ 10,190	$ 7,126
Return accrual included in other long-term liabilities	4,000	3,200
Product returns
Beginning balance	10,339	8,030
Provision for product returns	11,810	7,305
Credits issued to third parties	(7,945)	(4,996)
Ending balance	$ 14,204	$ 10,339

Income (Loss) per Share Attri_3

Income (Loss) per Share Attributable to Amphastar Pharmaceuticals, Inc. Stockholders (Narrative) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Exercise Price of Excluded Securities		$ 21.99
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Shares	1,917,437	803,257	10,105,565
Antidilutive Securities Excluded from Computation of Earnings Per Share, Exercise Price of Excluded Securities	$ 20.85
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Shares			1,206,661
Employee Stock Purchase Plan (ESPP)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Shares			51,792

Income (Loss) per Share Attri_4

Income (Loss) per Share Attributable to Amphastar Pharmaceuticals, Inc. Stockholders (Calculation of Basic and Diluted Net Income (Loss) Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic and dilutive numerator:
Net Income (Loss) Attributable to Parent	$ 1,403	$ 48,939	$ (5,738)
Denominator:
Shares outstanding	47,038	46,982	46,395
Weighted-average shares outstanding-basic	47,038	46,982	46,395
Net effect of dilutive securities:
Incremental shares from equity awards	2,086	2,925
Weighted-average shares outstanding - diluted	49,124	49,907	46,395
Net income (loss) per share - basic	$ 0.03	$ 1.04	$ (0.12)
Net income (loss) per share - diluted	$ 0.03	$ 0.98	$ (0.12)

Segment Reporting (Selected Fin

Segment Reporting (Selected Financial Information by Reporting Segment) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments \| segment	2
Net revenues:
Net Revenue	$ 349,846	$ 322,357	$ 294,666
Gross profit (loss):
Gross Profit	143,340	131,923	106,985
Operating expenses	132,386	131,962	115,608
Income (loss) from operations	10,954	(39)	(8,623)
Non-operating income (expenses)	(6,317)	60,267	(1,303)
Income (loss) before income taxes	4,637	60,228	(9,926)
Finished Pharmaceutical Products
Net revenues:
Net Revenue	331,368	302,000	271,059
Gross profit (loss):
Gross Profit	151,645	136,576	113,220
API
Net revenues:
Net Revenue	18,478	20,357	23,607
Gross profit (loss):
Gross Profit	$ (8,305)	$ (4,653)	$ (6,235)

Segment Reporting (Summary of N

Segment Reporting (Summary of Net Revenues by Product Segment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	$ 349,846	$ 322,357	$ 294,666
Finished Pharmaceutical Products
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	331,368	302,000	271,059
Finished Pharmaceutical Products \| Enoxaparin
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	48,681	42,695	53,371
Finished Pharmaceutical Products \| Lidocaine
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	41,113	46,013	43,328
Finished Pharmaceutical Products \| Phytonadione
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	42,646	45,786	41,897
Finished Pharmaceutical Products \| Naloxone
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	33,416	34,761	37,195
Finished Pharmaceutical Products \| Epinephrine
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	23,799	13,885	10,055
Finished Pharmaceutical Products \| Primatene Mist
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	51,725	18,065	3,574
Finished Pharmaceutical Products \| Other Finished Pharmaceutical Products
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	$ 89,988	$ 100,795	$ 81,639

Segment Reporting (Depreciation

Segment Reporting (Depreciation and Amortization Expense by Reporting Segment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Depreciation and amortization expense	$ 9,030	$ 7,058	$ 6,053
Finished Pharmaceutical Products
Segment Reporting Information [Line Items]
Depreciation and amortization expense	5,766	5,581	4,872
API
Segment Reporting Information [Line Items]
Depreciation and amortization expense	$ 3,264	$ 1,477	$ 1,181

Segment Reporting (Summary of R

Segment Reporting (Summary of Revenues and Long-Lived Assets by Geographic Region) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Revenue	$ 349,846	$ 322,357	$ 294,666
Long-Lived Assets	280,709	253,548
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Revenue	333,093	304,896	279,122
Long-Lived Assets	129,401	126,383
CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Revenue	3,161	1,481
Long-Lived Assets	98,538	81,428
FRANCE
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Revenue	13,592	15,980	$ 15,544
Long-Lived Assets	$ 52,770	$ 45,737

Customer and Supplier Concent_3

Customer and Supplier Concentration (Details) - Customer Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2020customeritem	Dec. 31, 2019customeritem	Dec. 31, 2018item
Revenue, Major Customer [Line Items]
Number of major customers that are wholesale distributors	3
Accounts Receivable, Net
Revenue, Major Customer [Line Items]
Number of major customers \| customer	3	3
Net Revenues
Revenue, Major Customer [Line Items]
Number of major customers	3	3	3
AmerisourceBergen \| Accounts Receivable, Net
Revenue, Major Customer [Line Items]
Major Customers	9.00%	13.00%
AmerisourceBergen \| Net Revenues
Revenue, Major Customer [Line Items]
Major Customers	23.00%	24.00%	27.00%
Cardinal Health \| Accounts Receivable, Net
Revenue, Major Customer [Line Items]
Major Customers	17.00%	17.00%
Cardinal Health \| Net Revenues
Revenue, Major Customer [Line Items]
Major Customers	17.00%	22.00%	21.00%
McKesson \| Accounts Receivable, Net
Revenue, Major Customer [Line Items]
Major Customers	24.00%	34.00%
McKesson \| Net Revenues
Revenue, Major Customer [Line Items]
Major Customers	22.00%	25.00%	27.00%

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Values of the Company's Financial Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	$ 1,865	$ 1,865
Short-term investments	9,089	8,867
Restricted short-term investments	2,200	2,290
Fair value measurement	72,269	44,968
Recurring Basis \| Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps related to variable rate loans	(902)	(364)
Recurring Basis \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate bonds	1,307	2,789
Recurring Basis \| Money market
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	58,710	29,521
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash	1,865	1,865
Fair value measurement	60,575	31,386
Level 1 \| Money market
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	58,710	29,521
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	9,089	8,867
Restricted short-term investments	2,200	2,290
Fair value measurement	11,694	13,582
Level 2 \| Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps related to variable rate loans	(902)	(364)
Level 2 \| Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate bonds	$ 1,307	$ 2,789

Investments (Held-to_Maturity)

Investments (Held-to_Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 1,307	$ 2,790
Gross Unrealized Losses		(1)
Fair Value	1,307	2,789
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,307	2,790
Gross Unrealized Losses		(1)
Fair Value	$ 1,307	$ 2,789

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Summary of Intangible Assets) (Details) $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2018USD ($)	Feb. 28, 2017USD ($)item	Jun. 30, 2017USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Definite-lived intangible assets
Weighted-Average Life (Years)				12 years	12 years
Finite-Lived Intangible Assets, Gross				$ 12,587	$ 12,321
Accumulated Amortization				5,137	4,027
Finite-Lived Intangible Assets, Net				7,450	8,294
Indefinite-lived intangible assets
Indefinite-lived intangible assets				29,200
Goodwill recognized				3,940	3,634	$ 3,951
Subtotal, Original Cost				33,165	32,859
Subtotal, Net Book Value				33,165	32,859
Balance, Original Cost				45,752	45,180
Balance, Net Book Value				40,615	41,153
Proceeds received from sale of ANDAs						$ 4,400
Hikma Pharmaceuticals PLC
Indefinite-lived intangible assets
Number of Injectable Products Sold \| item		14
Sale price of intangible assets		$ 6,400
Proceeds received from sale of ANDAs	$ 4,400	$ 1,000	$ 1,000
Royalty Fee Percentage		2.00%
Finished Pharmaceutical Products
Indefinite-lived intangible assets
Goodwill recognized				3,940	3,634
Trademarks
Indefinite-lived intangible assets
Indefinite-lived intangible assets				$ 29,225	$ 29,225
Patents
Definite-lived intangible assets
Weighted-Average Life (Years)				12 years	12 years
Finite-Lived Intangible Assets, Gross				$ 486	$ 486
Accumulated Amortization				297	255
Finite-Lived Intangible Assets, Net				$ 189	$ 231
Land-use rights
Definite-lived intangible assets
Weighted-Average Life (Years)				39 years	39 years
Finite-Lived Intangible Assets, Gross				$ 2,540	$ 2,540
Accumulated Amortization				617	551
Finite-Lived Intangible Assets, Net				$ 1,923	$ 1,989
Other intangible assets
Definite-lived intangible assets
Weighted-Average Life (Years)					4 years
Finite-Lived Intangible Assets, Gross					$ 69
Accumulated Amortization					$ 69
International Medication Systems (UK) Limited \| Acquired international product rights
Definite-lived intangible assets
Weighted-Average Life (Years)				10 years	10 years
Finite-Lived Intangible Assets, Gross				$ 9,561	$ 9,226
Accumulated Amortization				4,223	3,152
Finite-Lived Intangible Assets, Net				$ 5,338	$ 6,074

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets (Summary of Changes in the Carrying Amount of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets
Beginning balance	$ 3,634	$ 3,951
Currency translation and other adjustments	306	(317)
Ending balance	$ 3,940	$ 3,634

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets (Summary of Expected Amortization Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
2021	$ 1,064
2022	1,045
2023	1,035
2024	1,035
2025	1,035
Thereafter	2,236
Finite-Lived Intangible Assets, Net	7,450	$ 8,294
Indefinite-lived intangibles	33,165
Balance, Net Book Value	40,615	41,153
Amortization expense	1,036	1,037	$ 1,987
Product rights
Amortization expense	$ 1,200	$ 1,000	$ 1,800

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	12 Months Ended
Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Raw materials and supplies	$ 47,051	$ 59,233
Work in process	37,257	35,548
Finished goods	12,523	15,720
Total inventory, net	96,831	110,501
Inventory adjustment to reflect net realizable value	13,900	9,400	$ 12,900
Enoxaparin
Inventory adjustment to reflect net realizable value	9,400	5,800	9,100
Inventory, Firm Purchase Commitment, Loss	$ 1,200	$ 1,300	$ 5,200

Property, Plant, and Equipmen_2

Property, Plant, and Equipment (Summary of Property, Plant, and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	$ 444,202	$ 398,261
Less accumulated depreciation and amortization	(184,147)	(164,405)
Total property, plant, and equipment, net	260,055	233,856
Buildings
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	124,326	117,928
Leasehold improvement
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	30,028	29,531
Land
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	7,719	7,603
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	211,666	164,802
Furniture, fixtures, and automobiles
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	26,482	22,043
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	$ 43,981	$ 56,354

Property, Plant, and Equipmen_3

Property, Plant, and Equipment (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant, and Equipment
Depreciation expense	$ 20,491	$ 17,073	$ 14,529
Interest Costs Capitalized	$ 1,800	$ 2,300	$ 2,200

Accounts Payable and Accrued _3

Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Payable and Accrued Liabilities.
Accrued customer fees and rebates	$ 9,029	$ 9,633
Accrued payroll and related benefits	24,597	21,872
Accrued product returns, current portion	10,190	7,126
Accrued loss on firm purchase commitments	1,223	3,352
Accrued litigation settlement	13,780
Other accrued liabilities	12,328	10,007
Total accrued liabilities	71,147	51,990
Accounts payable	24,357	25,061
Total accounts payable and accrued liabilities	$ 95,504	$ 77,051

Debt (Schedule of Debt) (Detail

Debt (Schedule of Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument
Equipment under Finance Leases	$ 526	$ 811
Total debt	46,449	47,135
Less current portion of long-term debt and finance leases	12,263	7,741
Long-term debt and finance leases, net of current portion	34,186	39,394
Mortgage Payable - Due May 2021 \| East West Bank
Debt Instrument
Long Term Debt	3,306	3,401
Equipment Loan - Due June 2021 \| East West Bank
Debt Instrument
Long Term Debt	612	1,837
Equipment Loan - Due December 2022 \| East West Bank
Debt Instrument
Long Term Debt	4,000	6,000
Equipment Loan - Due February 2024 \| East West Bank
Debt Instrument
Long Term Debt	5,254	3,570
Mortgage Payable - Due October 2026 \| East West Bank
Debt Instrument
Long Term Debt	3,334	3,400
Mortgage Payable - Due June 2027 \| East West Bank
Debt Instrument
Long Term Debt	8,510	8,659
Mortgage Payable - Due August 2027 \| Cathay Bank
Debt Instrument
Long Term Debt	7,268	7,452
Acquisition Loan - Due June 2024 \| Cathay Bank
Debt Instrument
Long Term Debt	8,710	10,928
Line of credit - Due June 2021 \| China Everbright Bank
Debt Instrument
Long Term Debt	764
Line of Credit - Due August 2021 \| China Merchant Bank
Debt Instrument
Long Term Debt	382
Line of Credit - Due October 2021 \| Bank of Nanjing
Debt Instrument
Long Term Debt	153
Equipment Line of Credit - Due September 2025 \| East West Bank
Debt Instrument
Long Term Debt	3,216
French Government Loan - Due June 2020 \| Seine-Normandie Water Agency
Debt Instrument
Long Term Debt		28
French Government Loan - Due July 2021 \| Seine-Normandie Water Agency
Debt Instrument
Long Term Debt	64	114
French Government Loan 4 - Due December 2026 \| Seine-Normandie Water Agency
Debt Instrument
Long Term Debt	$ 350	374
Payment Obligation To Merck
Debt Instrument
Long Term Debt		$ 561

Debt (Narrative) (Details)

Sep. 01, 2020USD ($)

Feb. 03, 2020USD ($)

Jan. 31, 2020USD ($)

Aug. 14, 2017USD ($)

Jun. 28, 2017USD ($)

May 18, 2017USD ($)building

May 11, 2017USD ($)

Sep. 08, 2016USD ($)building

Jan. 31, 2015USD ($)item

Apr. 30, 2014USD ($)

Apr. 22, 2014USD ($)

Mar. 31, 2020USD ($)

Jan. 31, 2019USD ($)

Dec. 31, 2018USD ($)

Jun. 30, 2018USD ($)

Jan. 31, 2015USD ($)item

Dec. 31, 2020USD ($)

Dec. 31, 2019

Dec. 31, 2018USD ($)

Oct. 31, 2020USD ($)

Aug. 31, 2020USD ($)

Jun. 30, 2020USD ($)

Jul. 31, 2019

Dec. 31, 2018loan

Mar. 31, 2016USD ($)

Jan. 08, 2016USD ($)building

Apr. 10, 2012USD ($)

Mar. 31, 2012USD ($)

Sep. 15, 2006USD ($)

Debt

Proceeds from borrowing under lines of credit

$ 1,238,000

$ 347,000

Seine-Normandie Water Agency

Debt

Principal amount

$ 700,000

Debt Instrument, Term

8 years

Number of Loans with Government Agency

500,000

Debt Instrument, Periodic Payment, Interest

$ 0

Notes Payable

400,000

Line of Credit Facility - Due Deember 2022 | East West Bank

Debt

Line of Credit Facility, Maximum Borrowing Capacity

$ 15,000,000

$ 10,000,000

Line of Credit outstanding

Mortgage Payable - Due May 2021 | East West Bank

Debt

Principal amount

$ 3,700,000

Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid

$ 3,300,000

Debt Instrument, Interest Rate, Stated Percentage

4.39%

Mortgage Payable - Due May 2021 | East West Bank | Rancho Cucamonga, California

Debt

Number of Buildings Securing Loan | building

Equipment Loan - Due June 2021 | East West Bank

Debt

Line of Credit Converted into Equipment Loan, Amount

$ 5,000,000

Debt Instrument, Interest Rate, Stated Percentage

4.86%

Line of Credit Facility, Maximum Borrowing Capacity

$ 5,000,000

Equipment Loan - Due December 2022 | East West Bank

Debt

Debt Instrument, Interest Rate, Stated Percentage

5.87%

Line of Credit Facility, Maximum Borrowing Capacity

$ 8,000,000

Proceeds from borrowing under lines of credit

$ 8,000,000

Draw down period

18 months

Term of loan after draw down period expires

48 months

Equipment Line of Credit - Due February 2024 | East West Bank

Debt

Line of Credit Converted into Equipment Loan, Amount

$ 6,600,000

Debt Instrument, Interest Rate, Stated Percentage

3.85%

Line of Credit Facility, Maximum Borrowing Capacity

$ 10,000,000

Line of Credit outstanding

3,600,000

Proceeds from borrowing under lines of credit

$ 3,000,000

Draw down period

12 months

Term of loan after draw down period expires

48 months

Equipment Line of Credit - Due February 2024 | East West Bank | Prime Rate

Debt

Debt Instrument, Basis Spread on Variable Rate

(1.00%)

Mortgage Payable - Due October 2026 | East West Bank | Rancho Cucamonga, California

Debt

Principal amount

$ 3,600,000

$ 2,800,000

Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid

$ 2,900,000

Number of Buildings Securing Loan | building

Debt Instrument, Interest Rate, Stated Percentage

4.15%

Mortgage Payable - Due October 2026 | East West Bank | LIBOR | Rancho Cucamonga, California

Debt

Debt Instrument, Basis Spread on Variable Rate

2.75%

Mortgage Payable - Due June 2027 | East West Bank

Debt

Principal amount

$ 9,000,000

Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid

$ 7,400,000

Debt Instrument, Interest Rate, Stated Percentage

4.79%

Mortgage Payable - Due June 2027 | East West Bank | Rancho Cucamonga, California

Debt

Number of Buildings Securing Loan | building

Mortgage Payable - Due June 2027 | East West Bank | Chino, California

Debt

Number of Buildings Securing Loan | building

Mortgage Payable - Due June 2027 | East West Bank | LIBOR

Debt

Debt Instrument, Basis Spread on Variable Rate

2.50%

Acquisition Loan - Due June 2024 | Cathay Bank

Debt

Principal amount

$ 21,900,000

Debt Instrument Loan Collateral Percentage

65.00%

Debt Instrument Covenant Period To Discharge Final Judgment

30 days

Debt Instrument Covenant Period To Discharge Final Judgment

30 days

Acquisition Loan - Due June 2024 | Cathay Bank | Prime Rate

Debt

Debt Instrument, Interest Rate, Stated Percentage

5.00%

Line of Credit Facility - Due May 2022 | Cathay Bank

Debt

Line of Credit Facility, Maximum Borrowing Capacity

$ 20,000,000

Line of Credit outstanding

Mortgage Payable - Due August 2027 | Cathay Bank | Canton, Massachusetts

Debt

Principal amount

$ 7,900,000

Debt Instrument, Interest Rate, Stated Percentage

4.70%

Duration by which the loan bears interest at fixed rate

5 years

Line of credit - Due June 2021 | China Everbright Bank

Debt

Debt Instrument, Interest Rate, Stated Percentage

4.05%

Line of Credit Facility, Maximum Borrowing Capacity

$ 700,000

Line of Credit outstanding

800,000

Line of Credit - Due August 2021 | China Merchant Bank

Debt

Debt Instrument, Interest Rate, Stated Percentage

4.35%

Line of Credit Facility, Maximum Borrowing Capacity

$ 400,000

Line of Credit outstanding

400,000

Line of Credit - Due October 2021 | Bank of Nanjing

Debt

Debt Instrument, Interest Rate, Stated Percentage

4.60%

Line of Credit Facility, Maximum Borrowing Capacity

$ 200,000

Line of Credit outstanding

200,000

Credit Agreement - Expires March 2023 | China Merchant Bank

Debt

Line of Credit Facility, Maximum Borrowing Capacity

$ 14,600,000

Draw down period

36 months

Equipment Line of Credit - Due September 2025 | East West Bank

Debt

Debt Instrument, Basis Spread on Variable Rate

0.50%

Line of Credit Facility, Maximum Borrowing Capacity

$ 10,000,000

Line of Credit outstanding

$ 3,200,000

Draw down period

12 months

Term of loan after draw down period expires

48 months

Payment Obligation To Merck

Debt

Principal amount

$ 16,000,000

Debt Instrument, Term

4 years

Minimum | Seine-Normandie Water Agency

Debt

Debt Instrument, Term

3 years

Minimum | Seine-Normandie Water Agency | Prime Rate

Debt

Debt Instrument, Interest Rate, Stated Percentage

4.00%

Minimum | Acquisition Loan - Due June 2024 | Cathay Bank | Prime Rate

Debt

Debt Instrument, Basis Spread on Variable Rate

4.00%

Minimum | Line of Credit Facility - Due May 2022 | Cathay Bank | Prime Rate

Debt

Debt Instrument, Interest Rate, Stated Percentage

4.00%

Minimum | Payment Obligation To Merck

Debt

Debt Instrument, Interest Rate, Stated Percentage

3.00%

Maximum | Seine-Normandie Water Agency

Debt

Debt Instrument, Term

6 years

Debt (Long-Term Debt Maturities

Debt (Long-Term Debt Maturities) (Details) $ in Thousands	Dec. 31, 2020USD ($)
Debt
2021	$ 11,950
2022	7,450
2023	5,666
2024	3,069
2025	1,273
Thereafter	16,515
Total long-term Debt	$ 45,923

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Tax Credit Carryforward [Line Items]
Federal income tax rate	21.00%	21.00%	21.00%
Deferred tax assets	$ 24,980	$ 25,873
Cumulative excess benefits of stock compensation established	5,564	6,390
Deferred Tax Assets, Valuation Allowance	15,780	10,438
Accumulated undistributed foreign earnings	51,600	44,900
Hanxin
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Valuation Allowance	2,100
AFP
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Valuation Allowance	13,700	$ 10,400
Federal \| Research and Development Tax Credit
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	$ 2,100
Tax Credit Carryforward, Expiration Date	Dec. 31, 2041
California \| Earliest Tax Year
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2032
California \| Research and Development Tax Credit
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	$ 21,900
State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards	1,600
Foreign Tax Authority \| FRANCE
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards	55,600
Foreign Tax Authority \| UNITED KINGDOM
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards	1,400
Foreign Tax Authority \| CHINA
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards	$ 12,400
Foreign Tax Authority \| CHINA \| Latest Tax Year
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2024

Income Taxes (Summary of Income

Income Taxes (Summary of Income Before Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income (loss) before income taxes:
United States	$ 15,634	$ 77,092	$ 3,580
Foreign	(10,997)	(16,864)	(13,506)
Income (loss) before income taxes	4,637	60,228	(9,926)
Income tax provision (benefit)	3,540	13,723	(3,266)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 1,097	$ 46,505	$ (6,660)
Income tax provision as a percentage of income before income taxes	76.30%	22.80%	32.90%

Income Taxes (Summary of Provis

Income Taxes (Summary of Provision (Benefit) for Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current provision (benefit):
Federal	$ 1,803	$ 4,283	$ 32
State	541	430	343
Foreign	279	1,514	773
Total current provision (benefit)	2,623	6,227	1,148
Deferred provision (benefit):
Federal	1,770	9,825	(687)
State	(1,489)	499	(3,900)
Foreign	636	(2,828)	173
Total deferred provision (benefit)	917	7,496	(4,414)
Total provision (benefit) for income taxes	$ 3,540	$ 13,723	$ (3,266)

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of the Statutory Federal Income Tax Rate to the Effective Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the statutory federal income tax rate to the Companys effective rate:
Statutory federal income tax (benefit)	21.00%	21.00%	21.00%
State tax expense, net of federal tax benefit	(16.20%)	1.20%	28.30%
Foreign tax rate differences	(20.10%)	1.20%	4.00%
Foreign valuation allowance	89.50%	2.50%	(42.00%)
Research and development credits	(65.10%)	(4.80%)	28.00%
Share-based compensation	18.70%	(1.50%)	5.10%
Executive compensation	48.10%	2.90%	(12.40%)
Deferred tax remeasurement			1.00%
Employee-related expenses	1.70%	0.20%	(0.40%)
Other	(1.30%)	0.10%	0.30%
Effective tax rate (benefit)	76.30%	22.80%	32.90%

Income Taxes (Schedule of Defer

Income Taxes (Schedule of Deferred Tax Assets/Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Research and development credits	$ 18,531	$ 18,603
Net operating loss carryforward	16,187	10,782
Inventory capitalization and reserve	7,744	8,518
Share-based compensation	5,564	6,390
Operating leases	4,999	4,741
Accrued expenses	4,340	4,153
Accrued chargebacks	3,927	3,729
Product return allowance	3,798	2,835
Intangibles	2,124	2,124
Other	2,633	85
Total deferred tax assets	69,847	61,960
Deferred tax liabilities:
Depreciation/amortization	13,735	11,528
Intangibles	7,298	6,743
Operating leases	4,808	4,571
Federal impact of state deferred taxes	3,987	3,674
Total deferred tax liabilities	29,828	26,516
Valuation allowance	(15,780)	(10,438)
Net deferred tax assets	$ 24,239	$ 25,006

Income Taxes (Reconciliation _2

Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	$ 8,331	$ 6,994	$ 7,438
Deductions based on tax positions related to prior years			(1,566)
Additions based on tax positions related to the current year	1,815	1,382	1,304
Deductions based on tax audit settlement		(45)	(126)
Deductions based on statute of limitations	(93)		(56)
Balance at the end of the year	$ 10,053	$ 8,331	$ 6,994

Income Taxes (Uncertain Income

Income Taxes (Uncertain Income Tax Positions - Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 9.9		$ 8.1
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions		$ 1.6
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 0.2	0.1	$ 0.3
Effective Income Tax Rate Reconciliation, Tax Settlement, State and Local, Amount		$ 0.1
Domestic Tax Authority \| Earliest Tax Year \| Federal
Income Tax Contingency [Line Items]
Open Tax Year	2017
Domestic Tax Authority \| Latest Tax Year \| Federal
Income Tax Contingency [Line Items]
Open Tax Year	2019
State and Local Jurisdiction \| Earliest Tax Year
Income Tax Contingency [Line Items]
Open Tax Year	2016
State and Local Jurisdiction \| Latest Tax Year
Income Tax Contingency [Line Items]
Open Tax Year	2019
Foreign Tax Authority \| Earliest Tax Year
Income Tax Contingency [Line Items]
Open Tax Year	2010
Foreign Tax Authority \| Latest Tax Year
Income Tax Contingency [Line Items]
Open Tax Year	2019

Stockholders' Equity (Common an

Stockholders' Equity (Common and Preferred Stock) (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity
Common stock; shares authorized	300,000,000	300,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Stockholders' Equity (Share Buy

Stockholders' Equity (Share Buyback Program) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity, Class of Treasury Stock [Line Items]
Stock buyback program, authorized amount	$ 140,000
Treasury Stock, Value, Acquired, Cost Method	$ 24,425	$ 22,291	$ 25,047
November 2014 Share Repurchase Plan
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Shares, Acquired (in Shares)	1,366,384	1,122,781	1,414,924
Treasury Stock, Value, Acquired, Cost Method	$ 24,400	$ 22,300	$ 25,000

Stockholders' Equity (The 2015

Stockholders' Equity (The 2015 Equity Incentive Plan) (Details) - shares	1 Months Ended	12 Months Ended
	Jan. 31, 2021	Dec. 31, 2020	Mar. 18, 2015
The 2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares)		6,386,666	5,300,296
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)			5,000,000
Equity Incentive Plan, Term		10 years
Share Based Compensation Arrangement By Share Based Payment Award Potential Number of Additional Shares Authorized (in Shares)		3,000,000
Share Based Compensation Arrangement by Share Based Payment Award Potential Annual Increase in Shares, Percentage		2.50%
The 2015 Equity Incentive Plan \| Minimum \| Shares subject to a minimum vesting requirement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares awarded subject to a minimum vesting requirement		95.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		1 year
The 2015 Equity Incentive Plan \| Subsequent Events
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	1,187,386
Amended and Restated 2005 Equity Plan \| Existing Employees \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Amended and Restated 2005 Equity Plan \| Existing Employees \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		5 years
Amended and Restated 2005 Equity Plan \| New Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
Amended and Restated 2005 Equity Plan \| Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		1 year

Stockholders' Equity (2014 Empl

Stockholders' Equity (2014 Employee Stock Purchase Plan) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation		$ 20,498	$ 17,295	$ 16,680
2014 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan, Offering Duration, Maximum	27 months
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date	85.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in Shares)		807,550
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares)		1,192,450
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)	2,000,000
Allocated share based compensation		$ 800	$ 700	$ 700

Stockholders' Equity (Key Assum

Stockholders' Equity (Key Assumptions Used in Determining Fair Value of Options Granted) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity
Average overall forfeiture rate	5.00%	5.00%	5.00%
Average volatility	43.10%	42.50%	39.90%
Risk-free interest rate	0.80%	2.40%	2.70%
Weighted-average expected life in years	5 years 8 months 12 days	5 years 8 months 12 days	5 years 8 months 12 days

Stockholders' Equity (Summary o

Stockholders' Equity (Summary of Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Options
Outstanding Options, Beginning of period		9,763,485
Options granted		1,803,048
Options exercised		(1,761,104)
Options cancelled		(112,180)
Options expired		(1,112,774)
Outstanding Options, End of period		8,580,475	9,763,485
Exercisable at the end of period		5,754,823
Weighted-Average Exercise Price
Outstanding Exercise Price (in dollars per share)		$ 15.26
Options granted (in dollars per share)		13.57
Options exercised (in dollars per share)		13.96
Options cancelled (in dollars per share)		16.42
Options expired (in dollars per share)		16.45
Outstanding Exercise Price (in dollars per share)		15	$ 15.26
Exercisable at the end of period (in dollars per share)		$ 14.41
Additional Disclosures
Outstanding Contractual Term (in Years)		5 years 2 months 12 days
Outstanding Intrinsic Value		$ 45,392
Exercisable remaining contractual term (in Years)		3 years 11 months 4 days
Exercisable aggregate intrinsic value		$ 33,548
Allocated share based compensation		$ 20,498	$ 17,295	$ 16,680
The 2015 Plan and 2005 Plan [Member] \| Minimum
Additional Disclosures
Outstanding Contractual Term (in Years)		5 years
Vesting term		3 years
The 2015 Plan and 2005 Plan [Member] \| Maximum
Additional Disclosures
Outstanding Contractual Term (in Years)		10 years
Vesting term		5 years
Employee Stock Option
Additional Disclosures
Allocated share based compensation		$ 9,100	$ 8,100	$ 8,200
Employee Stock Option \| President, General Counsel and member of board of directors
Additional Disclosures
Allocated share based compensation	$ 700
Vesting (percent)	80.00%

Stockholders' Equity (Informati

Stockholders' Equity (Information Relating to Option Grants and Exercises) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity
Weighted-average grant date fair value (in Dollars per share)	$ 5.51	$ 8.48	$ 7.80
Intrinsic value of options exercised	$ 9,169	$ 7,718	$ 7,372
Cash received	24,357	7,761	11,753
Total fair value of the options vested during the year	$ 9,978	$ 7,613	$ 7,972

Stockholders' Equity (Summary_2

Stockholders' Equity (Summary of Nonvested Options) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Options
Nonvested at beginning of period	2,747,133
Options granted	1,803,048
Options vested	(1,612,349)
Options forfeited	(112,180)
Nonvested at end of period	2,825,652	2,747,133
Weighted-Average Grant Date Fair Value
Nonvested at beginning of period (in dollars per share)	$ 6.99
Options granted (in dollars per share)	5.51	$ 8.48	$ 7.80
Options vested (in dollars per share)	6.19
Options forfeited (in dollars per share)	7.09
Nonvested at end of period (in dollars per share)	$ 6.50	$ 6.99
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options	$ 11.2
Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 2 months 12 days

Stockholders' Equity (Restricte

Stockholders' Equity (Restricted Stock Units) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding Contractual Term (in Years)		5 years 2 months 12 days
Allocated share based compensation		$ 20,498	$ 17,295	$ 16,680
Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		2 years 2 months 12 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		5 years
Allocated share based compensation		$ 10,000	$ 8,200	$ 7,700
Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		2 years 2 months 12 days
Share-based Compensation Arrangement by Share-based Payment Award, Restricted Stock Units, Number of Shares of Common Stock Per Award (in Shares)		1
Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options		$ 12,000
Maximum \| Amended and Restated 2005 Equity Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years
Board of Directors \| Amended and Restated 2005 Equity Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		1 year
President, General Counsel and member of board of directors \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	$ 1,600
Vesting (percent)	80.00%

Stockholders' Equity (Informa_2

Stockholders' Equity (Information Relating to RSU Grants and Deliveries) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Total RSUs outstanding at the beginning of the period	1,099,496
RSUs granted	733,566
RSUs forfeited	(48,490)
RSUs vested	(628,054)
Total RSUs outstanding at the end of the period	1,156,518
Total Fair Market Value of RSUs Issued
RSUs granted (in Dollars) \| $	$ 9,926
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Stock surrendered to fulfill tax withholding obligations	240,318

Stockholders' Equity (The 2018

Stockholders' Equity (The 2018 ANP Equity Incentive Plan) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	1,803,048
Outstanding Options, End of period	8,580,475	9,763,485
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	5 years 2 months 12 days
Allocated share based compensation	$ 20,498	$ 17,295	$ 16,680
The 2018 ANP Equity Incentive Plan \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	2,433,445	3,648,932
Outstanding Options, End of period	5,709,977
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	10 years
Allocated share based compensation	$ 700	$ 300

Stockholders' Equity (Share-Bas

Stockholders' Equity (Share-Based Compensation Expense Included in the Statement of Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	$ 20,498	$ 17,295	$ 16,680
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	4,248	3,819	3,923
Selling, distribution and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	456	387	383
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	14,089	11,538	10,853
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	$ 1,705	$ 1,551	$ 1,521

Employee Benefits (Details)

Employee Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Employee Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Benefits
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 1.9	$ 1.5	$ 1.3
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	0.30%	0.90%
Defined Benefit Plan, Benefit Obligation	$ 3	$ 2.4
Pension Cost	0.2	$ 0.2	$ 0.3
Deferred compensation plan assets	1.6
Deferred compensation plan liabilities	$ 1.7

Commitments and Contingencies_2

Commitments and Contingencies (Purchase Commitments) (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Nov. 30, 2012	Jan. 31, 2010	Dec. 31, 2020	Dec. 31, 2019
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Contractual Obligation			$ 46,449	$ 47,135
Commitments to Purchase Equipment and Raw Materials
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Long-term Purchase Commitment, Amount			48,800
Commitment to develop land \| ANP
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Contractual Obligation	$ 15,000
Payments for Construction in Process			$ 19,500
Land-use rights \| ANP
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Finite-lived Intangible Assets Acquired	$ 1,300	$ 1,200

Commitments and Contingencies_3

Commitments and Contingencies (Lease Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Right-of-use assets	$ 20,042	$ 18,805
Lease obligations	20,821
Operating lease cost	4,462	3,981
Short-term lease costs	649	613
Amortization of right-of-use assets	351	351
Interest on lease liabilities	33	46
Total financed lease cost	384	397
Total lease costs	$ 5,495	$ 4,991
Minimum
Lessee, Lease, Description [Line Items]
Lease renewal term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lease renewal term	6 years
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Right-of-use assets			$ 13,900
Lease obligations			$ 14,100

Commitments and Contingencies_4

Commitments and Contingencies (Lease Cash Flow Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies
Operating cash flows from operating Leases	$ 4,491	$ 3,531
Operating cash flows from finance leases	33	46
Financing cash flows from finance leases	369	354
Right-of use assets obtained in exchange for lease obligations: Operating leases	4,819	7,978
Right-of use assets obtained in exchange for lease obligations: Finance leases	$ 61	$ 143
Weighted-average remaining lease term (years), Operating leases	8 years 8 months 12 days	8 years 1 month 6 days
Weighted-average remaining lease term (years), Finance leases	2 years 3 months 18 days	2 years 9 months 18 days
Weighted-average discount rate, Operating leases	5.20%	5.90%
Weighted-average discount rate, Finance leases	5.00%	4.60%

Commitments and Contingencies_5

Commitments and Contingencies (Future Minimum Rental Payments) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Leases
2021	$ 4,362
2022	4,071
2023	2,819
2024	2,308
2025	1,976
Thereafter	10,691
Total lease payments	26,227
Less: interest	5,406
Total	20,821
Finance Leases
2021	250
2022	210
2023	50
2024	38
2025	18
Total lease payments	566
Less: interest	40
Total	526	$ 811
Total
2021	4,612
2022	4,281
2023	2,869
2024	2,346
2025	1,994
Thereafter	10,691
Total lease payments	26,793
Less: interest	5,446
Total	$ 21,347

Related-Party Transactions (Det

Related-Party Transactions (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Proceeds from private placement			$ 18,298	$ 38,036
Retirement agreement \| Senior Vice President of Engineering and President of AFP
Related Party Transaction [Line Items]
Retirement Compensation Expense		$ 1,100
Retirement agreement \| Senior Vice President of Engineering and President of AFP \| Cash compensation
Related Party Transaction [Line Items]
Cash compensation		$ 1,000
Compensation period		3 years
Retirement agreement \| Senior Vice President of Engineering and President of AFP \| Health insurance coverage
Related Party Transaction [Line Items]
Compensation period		6 years
ANP
Related Party Transaction [Line Items]
Proceeds from private placement	$ 56,300
Proceeds from private placement	56,300
ANP \| Management and directors
Related Party Transaction [Line Items]
Proceeds from private placement	$ 36,400

Litigation (Details)

Litigation (Details) $ in Thousands	Feb. 09, 2021USD ($)	Dec. 14, 2020USD ($)	Nov. 13, 2020USD ($)	May 20, 2019USD ($)	Sep. 21, 2011item	Dec. 31, 2020USD ($)
Loss Contingencies [Line Items]
Estimated Litigation Liability						$ 13,780
Employee Litigation v. International Medication Systems, Limited
Loss Contingencies [Line Items]
Estimated Litigation Liability						1,000
Employee Litigation v. International Medication Systems, Limited \| Subsequent Events
Loss Contingencies [Line Items]
Litigation Settlement, Amount	$ 1,000
Amphastar Pharmaceuticals, Inc. Vs Aventis Pharma, SA
Loss Contingencies [Line Items]
Estimated Litigation Liability						$ 12,800
Pending Litigation [Member] \| Enoxaparin Patent Litigation
Loss Contingencies [Line Items]
Number of Alleged Patent Infringements \| item					2
Settled Litigation [Member] \| Enoxaparin Patent Litigation
Loss Contingencies [Line Items]
Litigation Settlement, amount paid to the Company				$ 59,900
Settled Litigation [Member] \| Amphastar Pharmaceuticals, Inc. Vs Aventis Pharma, SA
Loss Contingencies [Line Items]
Litigation Settlement, Amount			$ 12,100
Costs and expenses			$ 700
Settled Litigation [Member] \| Amphastar Pharmaceuticals, Inc. Vs Aventis Pharma, SA \| Supplemental Action requesting revision of amount
Loss Contingencies [Line Items]
Litigation Settlement, Amount		$ 12,200