Amphastar Pharmaceuticals (AMPH) 10-Q 9 Aug 19 2019 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Aug. 02, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	Amphastar Pharmaceuticals, Inc.
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Central Index Key	0001297184
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Common Stock, Shares Outstanding		47,226,496
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 120,373	$ 86,337
Restricted cash	1,865	1,865
Short-term investments	2,836	2,831
Restricted short-term investments	2,290	2,290
Accounts receivable, net	48,823	52,163
Inventories	99,232	69,322
Income tax refunds and deposits	226	49
Prepaid expenses and other assets	8,489	5,485
Total current assets	284,134	220,342
Property, plant, and equipment, net	220,060	210,418
Finance lease right-of-use assets	985
Operating lease right-of-use assets	20,143
Goodwill and intangible assets, net	41,718	42,267
Other assets	13,515	9,918
Deferred tax assets	20,746	30,618
Total assets	601,301	513,563
Current Liabilities:
Accounts payable and accrued liabilities	88,171	87,418
Income taxes payable	3,150	1,187
Current portion of long-term debt and capital leases	6,941	18,229
Current portion of operating lease liabilities	2,737
Total current liabilities	100,999	106,834
Long-term reserve for income tax liabilities	415	415
Long-term debt and finance leases, net of current portion	39,793	31,984
Long-term operating lease liabilities, net of current portion	17,754
Deferred tax liabilities	1,025	1,031
Other long-term liabilities	9,027	8,940
Total liabilities	169,013	149,204
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; 52,212,760 and 47,217,675 shares issued and outstanding as of June 30, 2019 and 51,438,675 and 46,631,118 shares issued and outstanding as of December 31, 2018, respectively	5	5
Additional paid-in capital	355,436	344,434
Retained earnings	116,086	67,485
Accumulated other comprehensive loss	(4,223)	(4,013)
Treasury stock	(79,459)	(75,476)
Total Amphastar Pharmaceuticals, Inc. stockholders’ equity	387,845	332,435
Noncontrolling Interests	44,443	31,924
Total equity	432,288	364,359
Total liabilities and stockholders’ equity	$ 601,301	$ 513,563

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
CONDENSED 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	52,212,760	51,438,675
Common stock; shares outstanding	47,217,675	46,631,118

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Net revenues	$ 79,047	$ 71,040	$ 158,837	$ 129,433
Cost of revenues	46,660	44,976	95,547	86,397
Gross profit	32,387	26,064	63,290	43,036
Operating (income) expenses:
Selling, distribution, and marketing	2,992	1,876	6,133	3,597
General and administrative	12,426	11,669	28,753	22,667
Research and development	15,996	15,460	30,603	29,490
Total operating expenses	31,414	29,005	65,489	55,754
Income (loss) from operations	973	(2,941)	(2,199)	(12,718)
Non-operating income (expenses):
Interest income	143	106	291	230
Interest expense	(24)	(100)	(54)	(118)
Other income (expenses), net	60,001	(1,265)	59,422	(483)
Total non-operating income (expenses), net	60,120	(1,259)	59,659	(371)
Income (loss) before income taxes	61,093	(4,200)	57,460	(13,089)
Income tax expense (benefit)	14,173	(1,347)	12,694	(3,095)
Net income (loss)	46,920	(2,853)	44,766	(9,994)
Net loss attributable to noncontrolling interest	(867)		(3,889)
Net income (loss) attributable to Amphastar Pharmaceuticals, Inc.	$ 47,787	$ (2,853)	$ 48,655	$ (9,994)
Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders:
Basic (in Dollars per share)	$ 1.01	$ (0.06)	$ 1.04	$ (0.21)
Diluted (in Dollars per share)	$ 0.96	$ (0.06)	$ 0.97	$ (0.21)
Weighted-average shares used to compute net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders:
Basic (in Shares)	47,107	46,557	46,925	46,535
Diluted (in Shares)	49,894	46,557	50,155	46,535

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss) attributable to Amphastar Pharmaceuticals, Inc.	$ 47,787	$ (2,853)	$ 48,655	$ (9,994)
Other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc., net of income taxes
Foreign currency translation adjustment	(97)	(2,256)	(210)	(1,066)
Total other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc.	(97)	(2,256)	(210)	(1,066)
Total comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc.	$ 47,690	$ (5,109)	$ 48,445	$ (11,060)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash Flows From Operating Activities:
Net income (loss)	$ 44,766	$ (9,994)
Reconciliation to net cash provided by operating activities:
Loss on impairment and disposal of assets	850	743
Depreciation of property, plant, and equipment	8,311	6,513
Amortization of product rights, trademarks, and patents	526	1,451
Operating lease right-of-use asset amortization	1,390
Share-based compensation	8,706	8,862
Changes in deferred taxes	9,872
Changes in operating assets and liabilities:
Accounts receivable, net	1,700	(5,221)
Inventories	(30,012)	1,625
Prepaid expenses and other assets	(1,221)	1,715
Income tax refund, deposits, and payable	1,784	(3,209)
Operating lease right-of-use assets and liabilities, net	(1,297)
Accounts payable and accrued liabilities	2,738	10,408
Net cash provided by operating activities	48,113	12,893
Cash Flows From Investing Activities:
Purchases and construction of property, plant, and equipment	(24,467)	(24,591)
Sale of intangible assets		4,400
Purchase of short-term investments		(204)
Payment of deposits and other assets	(86)	(114)
Net cash used in investing activities	(24,553)	(20,509)
Cash Flows From Financing Activities:
Proceeds from private placement	18,298
Equity related tax payments, net of proceeds from equity plans	(157)	(294)
Purchase of treasury stock	(4,088)	(14,850)
Proceeds from borrowing under lines of credit		260
Repayments under lines of credit	(347)
Proceeds from issuance of long-term debt		8,000
Principal payments on long-term debt	(3,219)	(2,834)
Net cash provided by (used in) financing activities	10,487	(9,718)
Effect of exchange rate changes on cash	(11)	(190)
Net increase (decrease) in cash, cash equivalents and restricted cash	34,036	(17,524)
Cash, cash equivalents, and restricted cash at beginning of period	88,202	67,459
Cash, cash equivalents, and restricted cash at end of period	122,238	49,935
Noncash Investing and Financing Activities:
Capital expenditure included in accounts payable	6,631	5,840
Operating lease right-of-use assets	7,671
Equipment acquired under finance leases	61	14
Supplemental Disclosures of Cash Flow Information:
Interest paid, net of capitalized interest	1,277	1,078
Income taxes paid	$ 1,147	$ 149

General

General	6 Months Ended
	Jun. 30, 2019
General
General	Note 1. Genera Amphastar Pharmaceuticals, Inc., a California corporation, was incorporated in February 1996 and merged with and into Amphastar Pharmaceuticals, Inc., a Delaware corporation, in July 2004 (together with its subsidiaries, hereinafter referred to as the “Company”). The Company is a specialty 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 products are primarily distributed through drug retailers. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements of the Company for the year ended December 31, 2018, and the notes thereto as filed with the Securities and Exchange Commission, or SEC, in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with generally accepted accounting principles, or GAAP, have been condensed or omitted from the accompanying condensed consolidated financial statements. The accompanying year-end condensed consolidated balance sheet was derived from the audited financial statements. The accompanying interim financial statements are unaudited, but reflect all adjustments which are, in the opinion of management, necessary for a fair statement of the Company’s consolidated financial position, results of operations, comprehensive income (loss) and cash flows for the periods presented. Unless otherwise noted, all such adjustments are of a normal, recurring nature. The Company’s results of operations, comprehensive income (loss) and cash flows for the interim periods are not necessarily indicative of the results of operations and cash flows that it may achieve in future periods.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Basis of Presentation The unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries, and are prepared in accordance with United States GAAP, or GAAP. All intercompany activity has been eliminated in the preparation of the condensed consolidated financial statements. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments (consisting only of normal recurring 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 Fine Chemistry Co., Ltd., or Letop, (5) Nanjing Hanxin Pharmaceutical Technology Co., Ltd, or Hanxin, (6) Nanjing Baixin Trading Co. Ltd., or Baixin, (7) Amphastar France Pharmaceuticals, S.A.S., or AFP, (8) Amphastar UK Ltd., or AUK, and (9) 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 for aggregate gross proceeds of approximately $57 million. While investors were initially required to complete their contributions in cash by December 31, 2018, ANP granted an extension to certain investors. Certain investors contributed their payments in Chinese yuan, which resulted in a difference in U.S. dollars, or USD, due to currency fluctuations subsequent to the execution of the placement agreement. A total of $56.3 million was received by ANP and the difference that was received in USD was expensed in the quarter ended March 31, 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 loss after July 2, 2018, was attributed to the Company in accordance with the Company’s equity interest of approximately 58% in ANP. In 2018, the Company identified certain errors in its accounting primarily related to the depreciation of certain leasehold improvements within property, plant and equipment. The errors were not material to any of the Company’s prior period annual financial statements. However, for comparative purposes, the Company has revised the prior period consolidated financial statements included herein. As a result, the net loss for the three months ended June 30, 2018 increased by $0.1 million. The errors did not result in a change to the basic or diluted net loss per share for the three months ended June 30, 2018. The net loss for the six months ended June 30, 2018, did not materially change as a result of the error. However, the error resulted in a change to the basic and diluted net loss per share for the six months ended June 30, 2018 by $0.01 and $0.01, respectively. The balances of property, plant, and equipment, net and retained earnings as of June 30, 2018, were reduced by $4.7 million and $3.6 million, respectively. The error did not result in a change to the net cash provided by operating activities in the Company’s consolidated statement of cash flows for the six months ended June 30, 2018. Use of Estimates The preparation of condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates. The principal accounting estimates include determination of allowances for doubtful accounts and 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, self-insured claims, 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 statements of operations. The Company’s French subsidiary, AFP, maintains its book of record in euros. Its other Chinese subsidiaries maintain their books of record in Chinese yuan. Its U.K. 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 three and six months ended June 30, 2019, were $0.4 million loss and $0.2 million gain, respectively, and for the three and six months ended June 30, 2018, were $1.7 million loss and $0.8 million loss, respectively. The Company does not undertake hedging transactions to cover its foreign currency exposure. Comprehensive Income (Loss) For the three and six months ended June 30, 2019 and 2018, the Company included its foreign currency translation gain or loss as part of its comprehensive income (loss). Restricted Cash and Short-Term Investments Restricted cash and short-term investments are collateral required for the Company to effect standby letters of credit and to qualify for workers’ compensation self-insurance and to guarantee certain vendor payments in France. As of June 30, 2019 and December 31, 2018, restricted cash and short-term investments include $1.9 million in cash and $2.3 million in certificates of deposit, respectively. The certificates of deposit have original maturities greater than three months and are classified as short-term investments. 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. 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. 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 , which is aimed at providing financial statement users with more useful information about the expected credit losses on financial instruments and other commitments to extend credit. The standard update changes the impairment model for financial assets measured at amortized cost, requiring presentation at the net amount expected to be collected. The measurement of expected credit losses requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Available-for-sale debt securities with unrealized losses will be recorded through an allowance for credit losses. The ASU and the related clarifications subsequently issued by FASB will become effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020. Early adoption is permitted for interim or annual periods after December 31, 2019. The Company will be required to apply the standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company does not believe the adoption of this accounting guidance will have a material impact on its consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU No. 2017-04 Simplifying the Test for Goodwill Impairment , which eliminates the requirement to calculate the implied fair value of goodwill. An entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The update also eliminated the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. An entity is required to disclose the amount of goodwill allocated to each reporting unit with a zero or negative carrying amount of net assets. The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020, and applied on a prospective basis. Early adoption is permitted for interim and annual goodwill impairment testing dates after January 1, 2017. The Company currently does not believe that the adoption of this accounting guidance will have a material impact on its consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU No. 2018-13 Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement , which removes, modifies, and adds certain disclosure requirements to ASC 820, Fair Value Measurement . The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020. Early adoption is permitted. The Company does not believe that the adoption of this accounting guidance will have a material impact on its consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU No. 2018-14 Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans , which removes, modifies, and adds certain disclosure requirements to ASC 715-20, Defined Benefit Plans . The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2021. Early adoption is permitted. The Company does not believe that the adoption of this accounting guidance will have a material impact on its 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 , which requires indirect interests held through related parties in common control arrangements be considered on a proportional basis for determining whether fees paid to decision makers and service providers are variable interests. The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020. Early adoption is permitted. The Company currently does not believe that the adoption of this accounting guidance will have a material impact on its consolidated financial statements and related disclosures. In November 2018, the FASB issued ASU No. 2018-18 Clarifying the Interaction between Topic 808 and Topic 606 , which requires transactions in collaborative arrangements to be accounted for under ASC 606, Revenue from Contracts with Customers, or ASC 606, if the counterparty is a customer for a good or service that is a distinct unit of account. The amendments also preclude entities from presenting consideration from transactions with a collaborator that is not a customer together with revenue recognized from contracts with customers. The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020. Early adoption is permitted, including in any interim period. The Company is currently evaluating the impact that the adoption of this guidance will have on its consolidated financial statements and related disclosures.

Revenue Recognition

Revenue Recognition	6 Months Ended
	Jun. 30, 2019
Revenue Recognition
Revenue Recognition	Note 3. Revenue Recognition In accordance with ASC 606, revenue is recognized at the time that the Company’s customers obtain control of the promised goods. 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. 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 only records revenue to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved, by estimating and recording reductions to revenue for discounts, product returns, and pricing adjustments, such as wholesaler chargebacks and retailer rebates, in the same period that the related revenue is recorded. 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: Six Months Ended June 30, 2019 2018 (in thousands) Beginning balance $ 22,423 $ 18,470 Provision for chargebacks and rebates 58,001 55,372 Credits and payments issued to third parties (61,704) (55,999) Ending balance $ 18,720 $ 17,843 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 June 30, 2019 and December 31, 2018, $11.5 million and $12.0 million were included in accounts receivable, net, on the condensed consolidated balance sheets, respectively. The remaining provision of $7.2 million and $10.4 million 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: Six Months Ended June 30, 2019 2018 (in thousands) Beginning balance $ 8,030 $ 6,522 Provision for product returns 3,654 917 Credits issued to third parties (2,243) (865) Ending balance $ 9,441 $ 6,574 Of the provision of product returns as of June 30, 2019 and December 31, 2018, $6.6 million and $5.3 million were included in accounts payable and accrued liabilities on the condensed consolidated balance sheets, respectively. The remaining provision as of June 30, 2019 and December 31, 2018, of $2.8 million and $2.7 million was included in other long-term liabilities, respectively. For the six months ended June 30, 2019 and 2018 , the Company’s aggregate product return rate was 1.5% and 1.3% of qualified sales, respectively.

Income (loss) per share attribu

Income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders	6 Months Ended
	Jun. 30, 2019
Income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders
Income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders	Note 4. Income (Loss) per Share Attributable to Amphastar Pharmaceuticals, Inc. Shareholders Basic net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders 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. shareholders 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 2018 ANP Equity Incentive Plan, or the 2018 Plan. For the three and six months ended June 30, 2019, options to purchase 783,001 and 762,937 shares of stock, respectively, with a weighted-average exercise price of $21.98 per share and $22.00 per share, respectively, were excluded in the computation of diluted net income per common share attributable to Amphastar Pharmaceuticals, Inc.’s shareholders because the effect from the assumed exercise of these options would be anti-dilutive. Additionally, 3,648,932 options to purchase ANP stock were awarded to ANP employees, which represent approximately 2% of ANP’s total equity, were excluded in the computation of diluted net income per common share attributable to Amphastar Pharmaceuticals, Inc.’s shareholders because the effect from the assumed exercise of these options would be anti-dilutive. As the Company reported a net loss for the three and six months ended June 30, 2018, the diluted net loss per share attributable to Amphastar Pharmaceuticals, Inc. shareholders, as reported, equals the basic net loss per share attributable to Amphastar Pharmaceuticals, Inc. shareholders 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 three and six months ended June 30, 2018, net loss per share were 11,649,241 stock options, 1,232,237 non-vested RSUs, and 60,854 shares issuable under the Company’s 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: Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands, except per share data) Basic and dilutive numerator: Net income (loss) attributable to Amphastar Pharmaceuticals, Inc. $ 47,787 $ (2,853) $ 48,655 $ (9,994) Denominator: Weighted-average shares outstanding — basic 47,107 46,557 46,925 46,535 Net effect of dilutive securities: Incremental shares from equity awards 2,787 — 3,230 — Weighted-average shares outstanding — diluted 49,894 46,557 50,155 46,535 Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders — basic $ 1.01 $ (0.06) $ 1.04 $ (0.21) Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders — diluted $ 0.96 $ (0.06) $ 0.97 $ (0.21)

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2019
Segment Reporting
Segment Reporting	Note 5. 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 enoxaparin, naloxone, phytonadione, lidocaine, medroxyprogesterone acetate, Primatene ® Mist, as well as various other critical and non-critical care drugs. The API segment manufactures and distributes recombinant human insulin API and porcine insulin API for external customers and internal product development. Selected financial information by reporting segment is presented below: Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Net revenues: Finished pharmaceutical products $ 73,735 $ 63,241 $ 148,274 $ 116,358 API 5,312 7,799 10,563 13,075 Total net revenues 79,047 71,040 158,837 129,433 Gross profit: Finished pharmaceutical products 34,540 27,649 66,852 47,285 API (2,153) (1,585) (3,562) (4,249) Total gross profit 32,387 26,064 63,290 43,036 Operating expenses 31,414 29,005 65,489 55,754 Income (loss) from operations 973 (2,941) (2,199) (12,718) Non-operating income (expense) 60,120 (1,259) 59,659 (371) Income (loss) before income taxes $ 61,093 $ (4,200) $ 57,460 $ (13,089) 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: Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Finished pharmaceutical products net revenues: Enoxaparin $ 9,838 $ 8,715 $ 24,322 $ 15,722 Phytonadione 12,441 10,806 22,561 19,987 Lidocaine 10,082 10,010 22,061 19,792 Naloxone 7,833 11,133 15,197 20,060 Medroxyprogesterone 6,696 6,365 13,909 9,071 Epinephrine 3,139 3,687 5,818 6,910 Primatene ® Mist 2,512 — 5,409 — Other finished pharmaceutical products 21,194 12,525 38,997 24,816 Total finished pharmaceutical products net revenues $ 73,735 $ 63,241 $ 148,274 $ 116,358 Net revenues and carrying values of long-lived assets of enterprises by geographic regions are as follows: Net Revenue Long-Lived Assets Three Months Ended Six Months Ended June 30, June 30, June 30, December 31, 2019 2018 2019 2018 2019 2018 (in thousands) United States $ 74,781 $ 68,560 $ 151,238 $ 121,664 $ 106,803 $ 109,331 China 984 — 984 — 68,620 58,059 France 3,282 2,480 6,615 7,769 44,637 43,028 United Kingdom — — — — — — Total $ 79,047 $ 71,040 $ 158,837 $ 129,433 $ 220,060 $ 210,418

Customer and Supplier Concentra

Customer and Supplier Concentration	6 Months Ended
	Jun. 30, 2019
Customer and Supplier Concentration
Customer and Supplier Concentration	Note 6. 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 three and six months ended June 30, 2019 and 2018, and accounts receivable as of June 30, 2019 and December 31, 2018, respectively. The following table provides accounts receivable and net revenue information for these major customers: % of Total Accounts % of Net Receivable Revenue Three Months Ended Six Months Ended June 30, December 31, June 30, June 30, 2019 2018 2019 2018 2019 2018 McKesson 28 % 28 % 25 % 25 % 27 % 26 % Cardinal Health 20 % 21 % 21 % 20 % 23 % 21 % AmerisourceBergen 12 % 19 % 25 % 27 % 23 % 26 % 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	6 Months Ended
	Jun. 30, 2019
Fair Value Measurements
Fair Value Measurements	Note 7. Fair Value Measurements The accounting standards of the FASB, define 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 June 30, 2019, cash equivalents include money market accounts. Short-term investments consist of certificates of deposit with original expiration dates within 12 months. These 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 restrictions on restricted cash and short-term investments have a negligible effect on the fair value of these financial assets. The Company does not hold any significant Level 2 or Level 3 instruments that are measured for 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 June 30, 2019 and December 31, 2018, there were no adjustments to fair value for nonfinancial assets or liabilities.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2019
Goodwill and Intangible Assets
Goodwill and Intangible Assets	Note 8. 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 8,880 2,590 6,290 Patents 12 486 234 252 Land-use rights 39 2,540 519 2,021 Other intangible assets 4 69 69 — Subtotal 13 11,975 3,412 8,563 Indefinite-lived intangible assets Trademark * 29,225 — 29,225 Goodwill - Finished pharmaceutical products * 3,930 — 3,930 Subtotal * 33,155 — 33,155 As of June 30, 2019 * $ 45,130 $ 3,412 $ 41,718 Weighted-Average Accumulated Life (Years) Original Cost Amortization Net Book Value (in thousands) Definite-lived intangible assets Cortrosyn ® product rights 12 $ 27,134 $ 27,134 $ — IMS (UK) international product rights 10 8,911 2,153 6,758 Patents 12 486 213 273 Land-use rights 39 2,540 486 2,054 Other intangible assets 4 69 63 6 Subtotal 12 39,140 30,049 9,091 Indefinite-lived intangible assets Trademark * 29,225 — 29,225 Goodwill - Finished pharmaceutical products * 3,951 — 3,951 Subtotal * 33,176 — 33,176 As of December 31, 2018 * $ 72,316 $ 30,049 $ 42,267 * 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 Pharmaceuticals, Inc. 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. In 2017, the Company recognized a gain of $2.6 million within operating (income) expenses on its consolidated statement of operations. Goodwill The changes in the carrying amounts of goodwill were as follows: June 30, December 31, 2019 2018 (in thousands) Beginning balance $ 3,951 $ 4,461 Currency translation (21) (510) Ending balance $ 3,930 $ 3,951 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, an over-the-counter bronchodilator product, recorded at the allocated fair value of $29.2 million, which is its carrying value as of June 30, 2019. 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 to be phased out on December 31, 2011. In 2013, the Company filed a new drug application, or NDA, for Primatene ® Mist, which utilizes a non-CFC propellant. In November 2018, the FDA granted over-the-counter approval of the NDA for Primatene ® Mist, and the Company re-launched this product in December 2018.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2019
Inventories
Inventories	Note 9. Inventories Inventories consist of the following: June 30, December 31, 2019 2018 (in thousands) Raw materials and supplies $ 45,633 $ 30,153 Work in process 36,224 30,272 Finished goods 17,375 8,897 Total inventories $ 99,232 $ 69,322 Charges totaling $2.5 million and $5.7 million were included in the cost of revenues in the Company’s consolidated statements of operations for the three and six months ended June 30, 2019, respectively, to adjust the Company’s inventory and related firm inventory purchase commitments to their net realizable value. For the three and six months ended June 30, 2018, charges totaling $1.2 million and $3.1 million were included in the cost of revenues, respectively, to adjust the Company’s inventory and related firm inventory purchase commitments to their net realizable value.

Property, Plant, and Equipment

Property, Plant, and Equipment	6 Months Ended
	Jun. 30, 2019
Property, Plant, and Equipment
Property, Plant, and Equipment	Note 10. Property, Plant, and Equipment Property, plant, and equipment consist of the following: June 30, December 31, 2019 2018 (in thousands) Buildings $ 97,340 $ 96,287 Leasehold improvements 29,211 26,755 Land 7,619 7,628 Machinery and equipment 151,457 143,299 Furniture, fixtures, and automobiles 19,982 19,151 Construction in progress 70,716 66,390 Total property, plant, and equipment 376,325 359,510 Less accumulated depreciation (156,265) (149,092) Total property, plant, and equipment, net $ 220,060 $ 210,418

Accounts Payable and Accrued Li

Accounts Payable and Accrued Liabilities	6 Months Ended
	Jun. 30, 2019
Accounts Payable and Accrued Liabilities
Accounts Payable and Accrued Liabilities	Note 11. Accounts Payable and Accrued Liabilities Accounts payable and accrued liabilities consisted of the following: June 30, December 31, 2019 2018 (in thousands) Accrued customer fees and rebates $ 11,455 $ 15,215 Accrued payroll and related benefits 20,357 19,430 Accrued product returns, current portion 6,644 5,349 Reserve for net loss on firm purchase commitments 3,403 5,355 Other accrued liabilities 14,850 10,746 Total accrued liabilities 56,709 56,095 Accounts payable 31,462 31,323 Total accounts payable and accrued liabilities $ 88,171 $ 87,418

Debt

Debt	6 Months Ended
	Jun. 30, 2019
Debt
Debt	Note 12. Debt Debt consists of the following: June 30, December 31, 2019 2018 (in thousands) Loans with East West Bank Equipment loan paid off January 2019 $ — $ 128 Line of credit facility due December 2020 — — Mortgage payable due February 2021 3,446 3,491 Equipment loan due June 2021 2,449 3,061 Equipment loan due December 2022 7,000 8,000 Line of credit facility due February 2024 — — Mortgage payable due October 2026 3,432 3,463 Mortgage payable due June 2027 8,732 8,801 Loans with Cathay Bank Line of credit facility due May 2020 — — Mortgage payable due August 2027 7,540 7,627 Acquisition loan due June 2024 11,979 13,025 Loans with Bank of Nanjing Working capital loan paid off June 2019 — 347 Loans with Seine-Normandie Water Agency French government loan due June 2020 26 French government loan due July 2021 176 French government loans due December 2026 438 Payment Obligation to Merck 558 552 Equipment under Finance Leases 958 — Equipment under Capital Leases — 1,055 Total debt 46,734 50,213 Less current portion of long-term debt 6,941 18,229 Long-term debt, net of current portion $ 39,793 $ 31,984 As of June 30, 2019, the fair value of the loans listed above approximated their carrying amount. The interest rate used in the fair value estimation was determined to be a Level 2 input. For certain loans with East West Bank, the Company has entered into fixed interest rate swap contracts to exchange the variable interest rates for fixed interest rates over the life of certain debt instruments without the exchange of the underlying notional debt amount. The interest rate swap contracts do not qualify for hedge accounting and are recorded at fair value based on Level 2 inputs. These swap contracts had an aggregate fair value of $0.4 million and $0.2 million as of June 30, 2019 and December 31, 2018, respectively. The change in fair value is recorded in other income (expense) in the Company’s condensed consolidated statement of operations. Acquisition loan – Due June 2024 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 , with a minimum interest rate of 5.00%. Beginning in August 2019, and through the maturity date, the Company must make monthly payments of principal and interest based on the then outstanding amount of the loan amortized over a 60-month period. Covenants At June 30, 2019 and December 31, 2018, the Company was in compliance with its debt covenants, which include a minimum current ratio, minimum debt service coverage, minimum tangible net worth, maximum debt-to-effective-tangible-net-worth ratio, and minimum deposit requirement computed on a consolidated basis. The profitability-related covenants for loans with Cathay Bank were not effective as of June 30, 2019 or December 31, 2018. Such covenants will become effective as of December 31, 2019.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Taxes
Income Taxes	Note 13. Income Taxes The following table sets forth the Company’s income tax provision (benefit) for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Income (loss) before taxes $ 61,093 $ (4,200) $ 57,460 $ (13,089) Income tax provision (benefit) 14,173 (1,347) 12,694 (3,095) Net income (loss) $ 46,920 $ (2,853) $ 44,766 $ (9,994) Income tax provision (benefit) as a percentage of loss before income taxes 23.2 % 32.1 % 22.1 % 23.6 % The decrease in the Company’s effective tax rate for the three and six months ended June 30, 2019, was primarily due to differences in pre-tax income (loss) positions and timing of discrete tax items. 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. M anagement 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 has discontinued recognizing AFP’s income tax benefits by recording a full valuation allowance until it is determined that it is more likely than not that AFP will generate sufficient taxable income to realize its deferred income tax assets. In 2019, for purposes of computing its annual effective tax rate, the Company did not benefit from its losses in the states where it files separately. This increased the Company’s income tax provision by an immaterial amount during the three and six months ended June 30, 2019.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2019
Stockholders' Equity
Stockholders' Equity	Note 14. Stockholders' Equity The changes in stockholders’ equity for the three and six months ended June 30, 2019 and 2018 consisted of the following: Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Stockholders’ equity beginning balance $ 380,266 $ 323,616 $ 364,359 $ 333,736 Beginning balance adjustment as a result of the adoption of new accounting standards — — (54) 582 Net income (loss) attributable to Amphastar Pharmaceuticals, Inc. 47,787 (2,853) 48,655 (9,994) Other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc. (97) (2,256) (210) (1,066) Net proceeds from the private placement of ANP — — 18,966 — Net loss attributable to non-controlling interests (867) — (3,889) — Net proceeds from equity plans, net of withholding tax payments 2,240 1,499 (157) (294) Share-based compensation expense 4,032 4,196 8,706 8,862 Purchase of treasury stock (1,073) (7,226) (4,088) (14,850) Stockholders’ equity ending balance $ 432,288 $ 316,976 $ 432,288 $ 316,976 Share Buyback Program Pursuant to the Company’s existing share buyback program, the Company purchased 50,980 and 196,459 shares of its common stock during the three and six months ended June 30, 2019, for total consideration of $1.1 million and $4.1 million, respectively. The Company purchased 430,137 and 837,741 shares of its common stock during the three and six months ended June 30, 2018, for total consideration of $7.2 million and $14.8 million, respectively. In May 2019, the Company’s Board of Directors authorized an increase of $20.0 million to the Company’s share buyback program, which is expected to continue for an indefinite period of time. The primary goal of the program is to offset dilution created by the Company’s equity compensation programs. 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 and applicable laws. 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. The 2015 Equity Incentive Plan As of June 30, 2019, the Company reserved an aggregate of 6,137,364 shares of common stock for future issuance under the 2015 Equity Incentive Plan, or the 2015 Plan, including 1,165,778 shares which were reserved in January 2019 pursuant to the evergreen provision in the 2015 Plan. 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 Employee Stock Purchase Plan 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 , non-vested stock options held by non-employees were revalued at each balance sheet date. As a result of the Company’s early adoption of the guidance in July 2018, stock options held by non-employees are no longer revalued after grant. The portion that is ultimately expected to vest is amortized and recognized in compensation expense on a straight-line basis over the requisite service period, generally from the grant date to the vesting date. The weighted-averages for key assumptions used in determining the fair value of options granted during the three and six months ended June 30, 2019 and 2018, are as follows: Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 Average volatility 43.4 % 41.7 % 42.5 % 39.9 % Risk-free interest rate 2.0 % 2.8 % 2.4 % 2.7 % Weighted-average expected life in years 5.0 4.9 5.7 5.7 Dividend yield rate — % — % — % — % A summary of option activity for the six months ended June 30, 2019, 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, 2018 10,105,565 $ 14.69 Options granted 1,033,268 20.96 Options exercised (1,074,413) 15.60 Options cancelled (5,219) 18.90 Options expired (2,325) 14.65 Outstanding as of June 30, 2019 10,056,876 $ 15.23 5.16 $ 59,792 Exercisable as of June 30, 2019 7,311,977 $ 14.18 4.13 $ 50,760 (1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the estimated fair value of the Company’s common stock for those awards that have an exercise price below the estimated fair value at June 30, 2019. For the three and six months ended June 30, 2019 , the Company recorded expenses of $1 .8 million and $4 .2 million, respectively, related to stock options granted. For the three and six months ended June 30, 2018 , the Company recorded expenses of $2.0 million and $4.6 million, respectively, related to stock options granted under all plans. Information relating to option grants and exercises is as follows: Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands, except per share data) Weighted-average grant date fair value per option share $ 8.17 $ 6.53 $ 8.46 $ 7.79 Intrinsic value of options exercised 452 277 5,822 1,338 Cash received from options exercised 1,108 650 5,047 2,511 Total fair value of the options vested during the year 388 1,383 7,502 7,790 A summary of the status of the Company’s non-vested options as of June 30, 2019, and changes during the six months ended June 30, 2019, is presented below: Weighted-Average Grant Date Options Fair Value Non-vested as of December 31, 2018 3,279,026 $ 5.47 Options granted 1,033,268 8.46 Options vested (1,562,176) 4.80 Options forfeited (5,219) 8.12 Non-vested as of June 30, 2019 2,744,899 6.97 As of June 30, 2019, there was $15.2 million of total unrecognized compensation cost, net of forfeitures, related to non-vested stock option based compensation arrangements granted. The cost is expected to be recognized over a weighted-average period of 2.5 years and will be adjusted for future changes in estimated forfeitures. 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 three and six months ended June 30, 2019, the Company recorded expenses of $2.0 million and $4.1 million, respectively, related to RSU awards granted . During the three and six months ended June 30, 2018, the Company recorded expenses of $2.0 million and $3.9 million, respectively, related to RSU awards granted. As of June 30, 2019, there was $16.5 million of total unrecognized compensation cost, net of forfeitures, related to non-vested RSU-based compensation arrangements granted. The cost is expected to be recognized over a weighted-average period of 2.5 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, 2018 1,206,661 RSUs granted 431,697 $ 8,733 RSUs forfeited (2,976) RSUs vested (2) (530,506) RSUs outstanding at June 30, 2019 1,104,876 (1) The total fair market value is derived from the number of RSUs granted times the stock price on the date of grant. (2) Of the vested RSUs, 233,539 shares of common stock were surrendered to fulfill tax withholding obligations. The Company recorded share-based compensation expense and it is included in the Company’s consolidated statement of operations as follows: Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Cost of revenues $ 959 $ 981 $ 2,238 $ 2,141 Operating expenses: Selling, distribution, and marketing 95 104 189 211 General and administrative 2,648 2,743 5,439 5,636 Research and development 330 368 840 874 Total share-based compensation $ 4,032 $ 4,196 $ 8,706 $ 8,862 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. In June 2019, ANP issued 3,648,932 stock options to its employees under the 2018 Plan all of which were still outstanding at June 30, 2019. The options vest over a period of approximately four years and have up to a 10 year contractual term. The total fair value of the options awarded was $2.1 million. For the three and six months ended June 30, 2019, the Company recorded an immaterial amount of expense related to stock options issued by ANP under the 2018 Plan.

Employee Benefits

Employee Benefits	6 Months Ended
	Jun. 30, 2019
Employee Benefits
Employee Benefits	Note 15. 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 three and six months ended June 30, 2019 were approximately $0.4 million and $0.7 million, respectively, compared to the prior year expense of $0.3 million and $0.6 million for the three and six months ended June 30, 2018, respectively. Defined Benefit Pension Plan In connection with the AFP acquisition, the Company assumed an obligation associated with a defined-benefit plan for eligible employees of AFP. 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 0.9% and 1.70% as of June 30, 2019 and December 31, 2018, 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 $2.2 million and $2.2 million at June 30, 2019 and December 31, 2018, respectively. The Company recorded an immaterial amount of expense under the plan for the three months ended June 30, 2019, and $0.1 million for the six months ended June 30, 2019. The Company recorded an immaterial amount of expense under the plan for the three months ended June 30, 2018, and $0.1 million for the six months ended June 30, 2018.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies
Commitments and Contingencies	Note 16. 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 in the consolidated balance sheets of approximately $14.1 million 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. 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 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 three and six months ended June 30, 2019 were as follows: Three Months Ended Six Months Ended June 30, June 30, 2019 2019 (in thousands) Operating lease costs $ 902 $ 1,790 Short-term lease costs 177 307 Finance lease costs Amortization of right-of-use assets 88 171 Interest on lease liabilities 12 24 Total finance lease costs $ 100 $ 195 Total lease costs $ 1,179 $ 2,292 Other information to leases are as follows: Six Months Ended June 30, 2019 Supplemental cash flow information (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 $ 1,648 Operating cash flows from finance leases 24 Financing cash flows from finance leases 171 Right-of use assets obtained in exchange for lease liabilities Operating leases 7,663 Finance leases 61 Weighted-average remaining lease term (years) Operating leases 8.4 Finance leases 2.9 Weighted-average discount rate Operating leases 5.9 % Finance leases 4.6 % Future minimum rental payments under operating leases that have initial or remaining non-cancelable lease terms in excess of 12 months as of June 30, 2019, are as follows: Operating Finance Leases Leases Total (in thousands) 2019 (excluding the Six Months Ended June 30, 2019) $ 1,844 $ 163 $ 2,007 2020 4,111 375 4,486 2021 4,335 298 4,633 2022 3,651 175 3,826 2023 2,429 14 2,443 Thereafter 10,167 6 10,173 Total lease payments $ 26,537 $ 1,031 $ 27,568 Less: interest 6,046 73 6,119 Total $ 20,491 $ 958 $ 21,449 Purchase Commitments As of June 30, 2019, the Company has entered into commitments to purchase equipment and raw materials for an aggregate amount of approximately $55.1 million. The Company anticipates that most of these commitments with remaining terms in excess of one year will be fulfilled by 2020. 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 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 June 30, 2019, the Company has spent $8.3 million on such construction. The Company anticipates that this spending commitment will be met by the end of 2019.

Related-Party Transactions

Related-Party Transactions	6 Months Ended
	Jun. 30, 2019
Related-Party Transactions
Related-Party Transactions	Note 17. 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, 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 from management and directors were approximately $29.7 million.

Litigation

Litigation	6 Months Ended
	Jun. 30, 2019
Litigation
Litigation	Note 18. 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.” The lawsuit was filed in the United States District Court for the District of Massachusetts, or the Massachusetts District Court. On September 17, 2015, the Company initiated a lawsuit by filing a complaint in the California District Court against Momenta and Sandoz, or the Defendants. The Company’s complaint generally asserts that Defendants have engaged in certain types of illegal, monopolistic, and anticompetitive conduct giving rise to various causes of action against them. On May 20, 2019, the Company and the Plaintiffs entered into a Settlement Agreement to fully settle the patent litigation and antitrust litigation. The Settlement Agreement was contingent upon the District Court’s granting a Joint Motion to Vacate the Patent Judgment and thereafter, the Plaintiffs’ payment of $59.9 Million to the Company. On June 18, 2019, the parties filed a Joint Motion to Vacate the Patent Judgment with the District Court, and on the same day, the District Court granted such motion. Accordingly, on June 19, 2019, the parties filed Joint Stipulations with the District Court to dismiss the patent litigation and the antitrust litigation, each of which is self-executing and effective upon filing pursuant to the Federal Rules of Civil Procedure 41(a)(1)(A)(ii). Furthermore, on June 26, 2019, the Federal Circuit issued an Order and a Mandate dismissing the appeal of the patent litigation. On June 27, 2019, pursuant to the Settlement Agreement, the Plaintiffs paid the Company $59.9 Million. The Company is not entitled to future rights or royalties related to this settlement. Accordingly, the Company recorded the settlement amount as other income (expenses), in its condensed consolidated statements of operations. False Claims Act Litigation In January 2009, the Company filed a qui tam complaint in the U.S. District Court for the Central District of California, or the California District Court, alleging that Aventis Pharma S.A., or Aventis, through its acquisition of a patent through false and misleading statements to the U.S. Patent and Trademark Office, as well as through false and misleading statements to the FDA, overcharged the federal and state governments for its Lovenox ® product. If the Company is successful in this litigation, it could be entitled to a portion of any damage award that the government ultimately may recover from Aventis. In October 2011, the California District Court unsealed the Company’s complaint. On February 28, 2014, Aventis filed a motion for summary judgment on the issue of the adequacy of the Company’s notice letter to the government, and the California District Court denied Aventis’ motion for summary judgment in a final order it issued on May 12, 2014. On June 9, 2014, at Aventis’ request, the California District Court issued an order certifying for appeal its order denying Aventis’ motion for summary judgment. On June 9, 2014, Aventis filed with the United States Court of Appeals for the Ninth Circuit, or the Ninth Circuit, a petition for permission to appeal the California District Court’s denial of Aventis’ motion for summary judgment, and the Company filed an opposition to Aventis’ petition on June 19, 2014. On August 22, 2014, the Ninth Circuit granted Aventis’ petition. The parties filed their respective appeal briefs with the Ninth Circuit. On November 10, 2016, the Ninth Circuit heard oral argument on the appeal. The California District Court set an evidentiary hearing for July 7, 2014 on the “original source” issue, a key element under the False Claims Act. The evidentiary hearing was conducted as scheduled, from July 7, 2014 through July 10, 2014. On July 13, 2015, the California District Court issued a ruling concluding that the Company is not an original source under the False Claims Act, and entered final judgment dismissing the case for lack of subject matter jurisdiction. On July 20, 2015, the Company filed with the Ninth Circuit a notice of appeal of the California District Court’s dismissal of the case, and Aventis filed a notice of cross-appeal on August 5, 2015. On November 12, 2015, Aventis filed a pleading asking that the California District Court impose various monetary penalties and fines against the Company, including disgorgement of enoxaparin revenues and attorneys’ fees expended by Aventis in this action, based on Aventis’ allegations that the Company engaged in sanctionable conduct. On November 23, 2015, the California District Court issued an order setting forth a procedure for sanctions proceedings as to the Company as well as its outside counsel. On December 24, 2015, the Company filed a pleading with the California District Court opposing the imposition of sanctions, and on January 20, 2016, Aventis filed a response pleading further pressing for the imposition of sanctions. On May 4, 2016, the California District Court issued three orders requesting that the Company and its outside counsel file a document showing cause as to why sanctions should not be imposed and to set up a conference call with the parties and the Court to discuss whether any discovery and/or a hearing is necessary. On June 13, 2016, the Company and its outside counsel each filed responses to the Court’s order to show cause as to why sanctions should not be imposed. On July 21, 2016, Aventis filed a response contending that the Court should impose sanctions. On February 10, 2017, the Court held a show cause hearing regarding the potential imposition of sanctions and took the matter under submission. On September 18, 2017, the District Court issued its decision that no sanctions will be imposed on either the Company or its counsel. On March 28, 2016, the Company filed its opening brief with the Ninth Circuit Court of Appeals setting forth detailed arguments as to why the False Claims Act litigation should not have been dismissed by the California District Court. On June 20, 2016, Aventis filed its principal brief in the appeal, responding to the Company’s arguments regarding dismissal of the False Claims Act litigation, and setting forth Aventis’ argument that it should be awarded attorneys’ fees and expenses. On September 19, 2016, the Company filed its reply brief to Aventis’ principal brief. On October 3, 2016, Aventis filed its reply brief in support of its cross-appeal of the District Court’s denial of attorneys’ fees. On November 10, 2016, the Ninth Circuit heard oral argument on the appeals. On May 11, 2017, the Ninth Circuit issued an opinion affirming the California District Court’s dismissal of the action for lack of subject matter jurisdiction; dismissing as moot Aventis’ appeal of the District Court’s denial of its motion for summary judgment on the issue of the adequacy of the Company’s notice letter to the government; reversing the District Court’s denial of Aventis’ motion for attorneys’ fees; and remanding the case to the District Court for resolution of the attorneys’ fees issue. 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, stating that it would refer the matter to a magistrate judge for a report and recommendation regarding the amount of the award to be made. On November 21, 2017, the District Court referred the matter to a magistrate judge. On August 7, 2018, Aventis filed its Application for Fees and Expenses. On November 26, 2018, the Company filed its Opposition to Aventis’ Application for Fees and Expenses. On February 12, 2019, following further briefing on the attorneys’ fee issue, the District Court approved of the parties’ consent for the Magistrate Judge to conduct all further proceedings in this matter at the district court level, including determining the amount of attorneys’ fees to be awarded and entering a final judgment. The Magistrate Judge held a hearing on the Application on May 8, 2019. At the May 8, 2019 hearing, the Magistrate Judge did not rule on the Application, but indicated that a written opinion on this Application for Fees and Expenses would be forthcoming. The Company intends to continue to vigorously defend against any imposition of attorneys’ fees and expenses in this case. Epinephrine Injection, 0.1 mg/mL Litigation On June 28, 2018, Belcher Pharmaceuticals, LLC, or Belcher, initiated a lawsuit by filing a complaint against IMS for infringement of U.S. Patent No. 9,283,197 (the “‘197 Patent”), with regard to IMS’s New Drug Application No. 211363, filed under 21 U.S.C. § 355(b)(2) of the Hatch-Waxman Act, for FDA approval to manufacture and sell 0.1 mg/mL epinephrine injections. On July 20, 2018, the Company filed a motion to dismiss Belcher’s complaint for patent infringement under Federal Rule of Civil Procedure 12(b)(6). On March 31, 2019, the Court denied the Company’s motion to dismiss. On April 15, 2019, the Company filed its Answer and Counterclaims. On April 24, 2019, the Court entered the Parties’ Joint Stipulation to stay the litigation until after Belcher’s June 2019 trial with Hospira, Inc. regarding the ‘197 patent. Belcher’s trial with Hospira regarding the ‘197 patent concluded in June 2019 but the Court has not yet ruled on the outcome of this trial. Thus, on July 3, 2019, the Parties filed a Joint Stipulation to stay the litigation pending the Court’s ruling on the outcome of Belcher’s trial with Hospira. The Company intends to vigorously defend this lawsuit. Vasopressin (20 units/mL) Patent Litigation On December 20, 2018, Par Pharmaceutical, Inc., Par Sterile Products, LLC and Endo Par Innovation Company (collectively, “Par”) initiated a patent lawsuit by filing a Complaint against the Company for infringement of U.S. Patent Nos. 9,375,478 (“the ‘478 Patent”), 9,687,526 (“the ‘526 Patent”), 9,744,209 (“the ‘209 Patent”), 9,744,239 (“the ‘239 Patent”), 9,750,785 (“the ‘785 Patent”) and 9,937,223 (“the ‘223 Patent”) (collectively, “Par Patents”) with regard to the Company’s Abbreviated New Drug Application No. 211,857 for FDA approval to manufacture and sell Vasopressin (20 units/ mL). The Company filed its Answer to this Complaint on February 19, 2019. On April 18, 2019, the Court held a scheduling conference and entered a Scheduling Order. Trial is scheduled for January 2021. The Company intends to vigorously defend this patent lawsuit. Other Litigation The Company is also subject to various other claims and lawsuits from time to time arising in the ordinary course of business. 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.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2019
Subsequent Events
Subsequent Events	Note 19. Subsequent Events Supply Agreement with MannKind Corporation In August 2019, the Company amended the Supply Agreement with MannKind Corporation, or MannKind, whereby MannKind’s aggregate total commitment of RHI API under the Supply Agreement was not reduced; however, the annual minimum purchase commitments of RHI API under the Supply Agreement were modified and extended for an additional two years through 2026, which timeframe would have previously lapsed after calendar year 2024. MannKind has agreed to pay the Company an amendment fee of $2.75 million, with $1.5 million due in September 2019, and the remaining balance due in December 2019.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2019
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries, and are prepared in accordance with United States GAAP, or GAAP. All intercompany activity has been eliminated in the preparation of the condensed consolidated financial statements. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments (consisting only of normal recurring 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 Fine Chemistry Co., Ltd., or Letop, (5) Nanjing Hanxin Pharmaceutical Technology Co., Ltd, or Hanxin, (6) Nanjing Baixin Trading Co. Ltd., or Baixin, (7) Amphastar France Pharmaceuticals, S.A.S., or AFP, (8) Amphastar UK Ltd., or AUK, and (9) 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 for aggregate gross proceeds of approximately $57 million. While investors were initially required to complete their contributions in cash by December 31, 2018, ANP granted an extension to certain investors. Certain investors contributed their payments in Chinese yuan, which resulted in a difference in U.S. dollars, or USD, due to currency fluctuations subsequent to the execution of the placement agreement. A total of $56.3 million was received by ANP and the difference that was received in USD was expensed in the quarter ended March 31, 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 loss after July 2, 2018, was attributed to the Company in accordance with the Company’s equity interest of approximately 58% in ANP. In 2018, the Company identified certain errors in its accounting primarily related to the depreciation of certain leasehold improvements within property, plant and equipment. The errors were not material to any of the Company’s prior period annual financial statements. However, for comparative purposes, the Company has revised the prior period consolidated financial statements included herein. As a result, the net loss for the three months ended June 30, 2018 increased by $0.1 million. The errors did not result in a change to the basic or diluted net loss per share for the three months ended June 30, 2018. The net loss for the six months ended June 30, 2018, did not materially change as a result of the error. However, the error resulted in a change to the basic and diluted net loss per share for the six months ended June 30, 2018 by $0.01 and $0.01, respectively. The balances of property, plant, and equipment, net and retained earnings as of June 30, 2018, were reduced by $4.7 million and $3.6 million, respectively. The error did not result in a change to the net cash provided by operating activities in the Company’s consolidated statement of cash flows for the six months ended June 30, 2018.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates. The principal accounting estimates include determination of allowances for doubtful accounts and 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, self-insured claims, 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 statements of operations. The Company’s French subsidiary, AFP, maintains its book of record in euros. Its other Chinese subsidiaries maintain their books of record in Chinese yuan. Its U.K. 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 three and six months ended June 30, 2019, were $0.4 million loss and $0.2 million gain, respectively, and for the three and six months ended June 30, 2018, were $1.7 million loss and $0.8 million loss, respectively. The Company does not undertake hedging transactions to cover its foreign currency exposure.
Comprehensive Income (Loss)	Comprehensive Income (Loss) For the three and six months ended June 30, 2019 and 2018, the Company included its foreign currency translation gain or loss as part of its comprehensive income (loss).
Restricted Cash and Short-term Investments	Restricted Cash and Short-Term Investments Restricted cash and short-term investments are collateral required for the Company to effect standby letters of credit and to qualify for workers’ compensation self-insurance and to guarantee certain vendor payments in France. As of June 30, 2019 and December 31, 2018, restricted cash and short-term investments include $1.9 million in cash and $2.3 million in certificates of deposit, respectively. The certificates of deposit have original maturities greater than three months and are classified as short-term investments.
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.
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.
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 , which is aimed at providing financial statement users with more useful information about the expected credit losses on financial instruments and other commitments to extend credit. The standard update changes the impairment model for financial assets measured at amortized cost, requiring presentation at the net amount expected to be collected. The measurement of expected credit losses requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Available-for-sale debt securities with unrealized losses will be recorded through an allowance for credit losses. The ASU and the related clarifications subsequently issued by FASB will become effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020. Early adoption is permitted for interim or annual periods after December 31, 2019. The Company will be required to apply the standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The Company does not believe the adoption of this accounting guidance will have a material impact on its consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU No. 2017-04 Simplifying the Test for Goodwill Impairment , which eliminates the requirement to calculate the implied fair value of goodwill. An entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The update also eliminated the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. An entity is required to disclose the amount of goodwill allocated to each reporting unit with a zero or negative carrying amount of net assets. The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020, and applied on a prospective basis. Early adoption is permitted for interim and annual goodwill impairment testing dates after January 1, 2017. The Company currently does not believe that the adoption of this accounting guidance will have a material impact on its consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU No. 2018-13 Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement , which removes, modifies, and adds certain disclosure requirements to ASC 820, Fair Value Measurement . The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020. Early adoption is permitted. The Company does not believe that the adoption of this accounting guidance will have a material impact on its consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU No. 2018-14 Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans , which removes, modifies, and adds certain disclosure requirements to ASC 715-20, Defined Benefit Plans . The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2021. Early adoption is permitted. The Company does not believe that the adoption of this accounting guidance will have a material impact on its 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 , which requires indirect interests held through related parties in common control arrangements be considered on a proportional basis for determining whether fees paid to decision makers and service providers are variable interests. The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020. Early adoption is permitted. The Company currently does not believe that the adoption of this accounting guidance will have a material impact on its consolidated financial statements and related disclosures. In November 2018, the FASB issued ASU No. 2018-18 Clarifying the Interaction between Topic 808 and Topic 606 , which requires transactions in collaborative arrangements to be accounted for under ASC 606, Revenue from Contracts with Customers, or ASC 606, if the counterparty is a customer for a good or service that is a distinct unit of account. The amendments also preclude entities from presenting consideration from transactions with a collaborator that is not a customer together with revenue recognized from contracts with customers. The guidance is effective for the Company’s interim and annual reporting periods during the year ending December 31, 2020. Early adoption is permitted, including in any interim period. The Company is currently evaluating the impact that the adoption of this guidance will have on its consolidated financial statements and related disclosures

Revenue Recognition (Tables)

Revenue Recognition (Tables)	6 Months Ended
	Jun. 30, 2019
Revenue Recognition
Schedule of chargeback and rebates provision analysis	Six Months Ended June 30, 2019 2018 (in thousands) Beginning balance $ 22,423 $ 18,470 Provision for chargebacks and rebates 58,001 55,372 Credits and payments issued to third parties (61,704) (55,999) Ending balance $ 18,720 $ 17,843
Schedule of product return liability analysis	Six Months Ended June 30, 2019 2018 (in thousands) Beginning balance $ 8,030 $ 6,522 Provision for product returns 3,654 917 Credits issued to third parties (2,243) (865) Ending balance $ 9,441 $ 6,574

Income (loss) per share attri_2

Income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders (Tables)	6 Months Ended
	Jun. 30, 2019
Income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders
Schedule of basic and diluted net income (loss) per share calculation	Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands, except per share data) Basic and dilutive numerator: Net income (loss) attributable to Amphastar Pharmaceuticals, Inc. $ 47,787 $ (2,853) $ 48,655 $ (9,994) Denominator: Weighted-average shares outstanding — basic 47,107 46,557 46,925 46,535 Net effect of dilutive securities: Incremental shares from equity awards 2,787 — 3,230 — Weighted-average shares outstanding — diluted 49,894 46,557 50,155 46,535 Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders — basic $ 1.01 $ (0.06) $ 1.04 $ (0.21) Net income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders — diluted $ 0.96 $ (0.06) $ 0.97 $ (0.21)

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2019
Segment Reporting
Schedule of financial information by reporting segment	Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Net revenues: Finished pharmaceutical products $ 73,735 $ 63,241 $ 148,274 $ 116,358 API 5,312 7,799 10,563 13,075 Total net revenues 79,047 71,040 158,837 129,433 Gross profit: Finished pharmaceutical products 34,540 27,649 66,852 47,285 API (2,153) (1,585) (3,562) (4,249) Total gross profit 32,387 26,064 63,290 43,036 Operating expenses 31,414 29,005 65,489 55,754 Income (loss) from operations 973 (2,941) (2,199) (12,718) Non-operating income (expense) 60,120 (1,259) 59,659 (371) Income (loss) before income taxes $ 61,093 $ (4,200) $ 57,460 $ (13,089)
Schedule of net revenues in the finished pharmaceutical products segment	Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Finished pharmaceutical products net revenues: Enoxaparin $ 9,838 $ 8,715 $ 24,322 $ 15,722 Phytonadione 12,441 10,806 22,561 19,987 Lidocaine 10,082 10,010 22,061 19,792 Naloxone 7,833 11,133 15,197 20,060 Medroxyprogesterone 6,696 6,365 13,909 9,071 Epinephrine 3,139 3,687 5,818 6,910 Primatene ® Mist 2,512 — 5,409 — Other finished pharmaceutical products 21,194 12,525 38,997 24,816 Total finished pharmaceutical products net revenues $ 73,735 $ 63,241 $ 148,274 $ 116,358
Schedule of net revenues and carrying values of long-lived assets by geographic region	Net Revenue Long-Lived Assets Three Months Ended Six Months Ended June 30, June 30, June 30, December 31, 2019 2018 2019 2018 2019 2018 (in thousands) United States $ 74,781 $ 68,560 $ 151,238 $ 121,664 $ 106,803 $ 109,331 China 984 — 984 — 68,620 58,059 France 3,282 2,480 6,615 7,769 44,637 43,028 United Kingdom — — — — — — Total $ 79,047 $ 71,040 $ 158,837 $ 129,433 $ 220,060 $ 210,418

Customer and Supplier Concent_2

Customer and Supplier Concentration (Tables)	6 Months Ended
	Jun. 30, 2019
Customer and Supplier Concentration
Schedule of accounts receivable and net revenues by major customer	% of Total Accounts % of Net Receivable Revenue Three Months Ended Six Months Ended June 30, December 31, June 30, June 30, 2019 2018 2019 2018 2019 2018 McKesson 28 % 28 % 25 % 25 % 27 % 26 % Cardinal Health 20 % 21 % 21 % 20 % 23 % 21 % AmerisourceBergen 12 % 19 % 25 % 27 % 23 % 26 %

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2019
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 8,880 2,590 6,290 Patents 12 486 234 252 Land-use rights 39 2,540 519 2,021 Other intangible assets 4 69 69 — Subtotal 13 11,975 3,412 8,563 Indefinite-lived intangible assets Trademark * 29,225 — 29,225 Goodwill - Finished pharmaceutical products * 3,930 — 3,930 Subtotal * 33,155 — 33,155 As of June 30, 2019 * $ 45,130 $ 3,412 $ 41,718 Weighted-Average Accumulated Life (Years) Original Cost Amortization Net Book Value (in thousands) Definite-lived intangible assets Cortrosyn ® product rights 12 $ 27,134 $ 27,134 $ — IMS (UK) international product rights 10 8,911 2,153 6,758 Patents 12 486 213 273 Land-use rights 39 2,540 486 2,054 Other intangible assets 4 69 63 6 Subtotal 12 39,140 30,049 9,091 Indefinite-lived intangible assets Trademark * 29,225 — 29,225 Goodwill - Finished pharmaceutical products * 3,951 — 3,951 Subtotal * 33,176 — 33,176 As of December 31, 2018 * $ 72,316 $ 30,049 $ 42,267 * Intangible assets with indefinite lives have an indeterminable average life.
Schedule of changes in carrying amounts of goodwill	June 30, December 31, 2019 2018 (in thousands) Beginning balance $ 3,951 $ 4,461 Currency translation (21) (510) Ending balance $ 3,930 $ 3,951

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2019
Inventories
Schedule of inventories	June 30, December 31, 2019 2018 (in thousands) Raw materials and supplies $ 45,633 $ 30,153 Work in process 36,224 30,272 Finished goods 17,375 8,897 Total inventories $ 99,232 $ 69,322

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	6 Months Ended
	Jun. 30, 2019
Property, Plant, and Equipment
Schedule of property, plant, and equipment	June 30, December 31, 2019 2018 (in thousands) Buildings $ 97,340 $ 96,287 Leasehold improvements 29,211 26,755 Land 7,619 7,628 Machinery and equipment 151,457 143,299 Furniture, fixtures, and automobiles 19,982 19,151 Construction in progress 70,716 66,390 Total property, plant, and equipment 376,325 359,510 Less accumulated depreciation (156,265) (149,092) Total property, plant, and equipment, net $ 220,060 $ 210,418

Accounts Payable and Accrued _2

Accounts Payable and Accrued Liabilities (Tables)	6 Months Ended
	Jun. 30, 2019
Accounts Payable and Accrued Liabilities
Schedule of accounts payable and accrued liabilities	June 30, December 31, 2019 2018 (in thousands) Accrued customer fees and rebates $ 11,455 $ 15,215 Accrued payroll and related benefits 20,357 19,430 Accrued product returns, current portion 6,644 5,349 Reserve for net loss on firm purchase commitments 3,403 5,355 Other accrued liabilities 14,850 10,746 Total accrued liabilities 56,709 56,095 Accounts payable 31,462 31,323 Total accounts payable and accrued liabilities $ 88,171 $ 87,418

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2019
Debt
Schedule of debt	June 30, December 31, 2019 2018 (in thousands) Loans with East West Bank Equipment loan paid off January 2019 $ — $ 128 Line of credit facility due December 2020 — — Mortgage payable due February 2021 3,446 3,491 Equipment loan due June 2021 2,449 3,061 Equipment loan due December 2022 7,000 8,000 Line of credit facility due February 2024 — — Mortgage payable due October 2026 3,432 3,463 Mortgage payable due June 2027 8,732 8,801 Loans with Cathay Bank Line of credit facility due May 2020 — — Mortgage payable due August 2027 7,540 7,627 Acquisition loan due June 2024 11,979 13,025 Loans with Bank of Nanjing Working capital loan paid off June 2019 — 347 Loans with Seine-Normandie Water Agency French government loan due June 2020 26 French government loan due July 2021 176 French government loans due December 2026 438 Payment Obligation to Merck 558 552 Equipment under Finance Leases 958 — Equipment under Capital Leases — 1,055 Total debt 46,734 50,213 Less current portion of long-term debt 6,941 18,229 Long-term debt, net of current portion $ 39,793 $ 31,984

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2019
Income Taxes
Summary of provision (benefit) for income taxes	Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Income (loss) before taxes $ 61,093 $ (4,200) $ 57,460 $ (13,089) Income tax provision (benefit) 14,173 (1,347) 12,694 (3,095) Net income (loss) $ 46,920 $ (2,853) $ 44,766 $ (9,994) Income tax provision (benefit) as a percentage of loss before income taxes 23.2 % 32.1 % 22.1 % 23.6 %

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2019
Stockholders' Equity
Summary of changes in stockholders' equity	Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Stockholders’ equity beginning balance $ 380,266 $ 323,616 $ 364,359 $ 333,736 Beginning balance adjustment as a result of the adoption of new accounting standards — — (54) 582 Net income (loss) attributable to Amphastar Pharmaceuticals, Inc. 47,787 (2,853) 48,655 (9,994) Other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc. (97) (2,256) (210) (1,066) Net proceeds from the private placement of ANP — — 18,966 — Net loss attributable to non-controlling interests (867) — (3,889) — Net proceeds from equity plans, net of withholding tax payments 2,240 1,499 (157) (294) Share-based compensation expense 4,032 4,196 8,706 8,862 Purchase of treasury stock (1,073) (7,226) (4,088) (14,850) Stockholders’ equity ending balance $ 432,288 $ 316,976 $ 432,288 $ 316,976
Schedule of key assumptions to determine fair value of options	Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 Average volatility 43.4 % 41.7 % 42.5 % 39.9 % Risk-free interest rate 2.0 % 2.8 % 2.4 % 2.7 % Weighted-average expected life in years 5.0 4.9 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, 2018 10,105,565 $ 14.69 Options granted 1,033,268 20.96 Options exercised (1,074,413) 15.60 Options cancelled (5,219) 18.90 Options expired (2,325) 14.65 Outstanding as of June 30, 2019 10,056,876 $ 15.23 5.16 $ 59,792 Exercisable as of June 30, 2019 7,311,977 $ 14.18 4.13 $ 50,760 The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the estimated fair value of the Company’s common stock for those awards that have an exercise price below the estimated fair value at June 30, 2019.
Schedule of information relating to options grants	Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands, except per share data) Weighted-average grant date fair value per option share $ 8.17 $ 6.53 $ 8.46 $ 7.79 Intrinsic value of options exercised 452 277 5,822 1,338 Cash received from options exercised 1,108 650 5,047 2,511 Total fair value of the options vested during the year 388 1,383 7,502 7,790
Schedule of the summary of nonvested options status	Weighted-Average Grant Date Options Fair Value Non-vested as of December 31, 2018 3,279,026 $ 5.47 Options granted 1,033,268 8.46 Options vested (1,562,176) 4.80 Options forfeited (5,219) 8.12 Non-vested as of June 30, 2019 2,744,899 6.97
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, 2018 1,206,661 RSUs granted 431,697 $ 8,733 RSUs forfeited (2,976) RSUs vested (2) (530,506) RSUs outstanding at June 30, 2019 1,104,876 (1) The total fair market value is derived from the number of RSUs granted times the stock price on the date of grant. (2) Of the vested RSUs, 233,539 shares of common stock were surrendered to fulfill tax withholding obligations.
Schedule of recorded share-based compensation expense under all plans	Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 (in thousands) Cost of revenues $ 959 $ 981 $ 2,238 $ 2,141 Operating expenses: Selling, distribution, and marketing 95 104 189 211 General and administrative 2,648 2,743 5,439 5,636 Research and development 330 368 840 874 Total share-based compensation $ 4,032 $ 4,196 $ 8,706 $ 8,862

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies
Schedule of lease information	The components of lease costs for the three and six months ended June 30, 2019 were as follows: Three Months Ended Six Months Ended June 30, June 30, 2019 2019 (in thousands) Operating lease costs $ 902 $ 1,790 Short-term lease costs 177 307 Finance lease costs Amortization of right-of-use assets 88 171 Interest on lease liabilities 12 24 Total finance lease costs $ 100 $ 195 Total lease costs $ 1,179 $ 2,292 Other information to leases are as follows: Six Months Ended June 30, 2019 Supplemental cash flow information (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 $ 1,648 Operating cash flows from finance leases 24 Financing cash flows from finance leases 171 Right-of use assets obtained in exchange for lease liabilities Operating leases 7,663 Finance leases 61 Weighted-average remaining lease term (years) Operating leases 8.4 Finance leases 2.9 Weighted-average discount rate Operating leases 5.9 % Finance leases 4.6 %
Schedule of future minimum payments	Operating Finance Leases Leases Total (in thousands) 2019 (excluding the Six Months Ended June 30, 2019) $ 1,844 $ 163 $ 2,007 2020 4,111 375 4,486 2021 4,335 298 4,633 2022 3,651 175 3,826 2023 2,429 14 2,443 Thereafter 10,167 6 10,173 Total lease payments $ 26,537 $ 1,031 $ 27,568 Less: interest 6,046 73 6,119 Total $ 20,491 $ 958 $ 21,449

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 02, 2018	Jul. 31, 2018	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Proceeds from private placement						$ 18,298
Gains and losses of intercompany foreign currency transactions			$ (400)		$ (1,700)	200	$ (800)
Selling, distribution, and marketing			2,992		1,876	6,133	3,597
Restricted Cash, Current			1,865			1,865		$ 1,865
Certificates of deposit			2,300			2,300		$ 2,300
Inventory adjustment to reflect net realizable value			$ 2,500		1,200	$ 5,700	$ 3,100
ANP
Proceeds from private placement		$ 57,000
Proceeds from private placement				$ 56,300
Equity interest retained post private placement	58.00%
Restatement adjustment
Impact of restatement on net income					100
Impact of restatement on earnings per share, basic							$ 0.01
Impact of restatement on earnings per share, diluted							$ 0.01
Impact of restatement on property, plant, and equipment, net					4,700		$ 4,700
Impact of restatement on retained earnings					$ 3,600		$ 3,600

Revenue Recognition (Analysis o

Revenue Recognition (Analysis of the Chargeback Provision) (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Beginning balance	$ 22,423	$ 18,470	$ 18,470
Provision for chargebacks and rebates	58,001	55,372
Credits and payments issued to third parties	(61,704)	(55,999)
Ending balance	18,720	$ 17,843	22,423
Accounts Receivable, Net
Provision for chargebacks and rebates	11,500		12,000
Accounts Payable and Accrued Liabilities [Member]
Provision for chargebacks and rebates	$ 7,200		$ 10,400

Revenue Recognition (Analysis_2

Revenue Recognition (Analysis of Product Return Liability) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Aggregate product return rate	1.50%	1.30%
Return accrual included in accounts payable and accrued liabilities	$ 6,644		$ 5,349
Return accrual included in other long-term liabilities	2,800		$ 2,700
Product returns
Beginning balance	8,030	$ 6,522
Provision for product returns	3,654	917
Credits issued to third parties	(2,243)	(865)
Ending balance	$ 9,441	$ 6,574

Income (loss) per share attri_3

Income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders (Narrative) (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 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	$ 21.98		$ 22
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Shares	783,001	11,649,241	762,937	11,649,241
Stock Options | ANP | Employees
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Shares	3,648,932
Shares awarded as approximate percentage of equity	2.00%
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		1,232,237		1,232,237
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		60,854		60,854

Income (loss) per share attri_4

Income (loss) per share attributable to Amphastar Pharmaceuticals, Inc. shareholders (Calculation of Basic and Diluted Net Income (Loss) Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Basic and dilutive numerator:
Net Income (Loss) Attributable to Parent	$ 47,787	$ (2,853)	$ 48,655	$ (9,994)
Denominator:
Shares outstanding	47,107	46,557	46,925	46,535
Weighted-average shares outstanding—basic	47,107	46,557	46,925	46,535
Net effect of dilutive securities:
Incremental shares from equity awards	2,787		3,230
Weighted-average shares outstanding — diluted	49,894	46,557	50,155	46,535
Net income (loss) per share — basic	$ 1.01	$ (0.06)	$ 1.04	$ (0.21)
Net income (loss) per share — diluted	$ 0.96	$ (0.06)	$ 0.97	$ (0.21)

Segment Reporting (Selected Fin

Segment Reporting (Selected Financial Information by Reporting Segment) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)segment	Jun. 30, 2018USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment			2
Net revenues:
Net Revenue	$ 79,047	$ 71,040	$ 158,837	$ 129,433
Gross Profit:
Gross Profit	32,387	26,064	63,290	43,036
Operating expenses	31,414	29,005	65,489	55,754
Income (loss) from operations	973	(2,941)	(2,199)	(12,718)
Non-operating income (expenses)	60,120	(1,259)	59,659	(371)
Income (loss) before income taxes	61,093	(4,200)	57,460	(13,089)
Finished Pharmaceutical Products
Net revenues:
Net Revenue	73,735	63,241	148,274	116,358
Gross Profit:
Gross Profit	34,540	27,649	66,852	47,285
API
Net revenues:
Net Revenue	5,312	7,799	10,563	13,075
Gross Profit:
Gross Profit	$ (2,153)	$ (1,585)	$ (3,562)	$ (4,249)

Segment Reporting (Summary of N

Segment Reporting (Summary of Net Revenues by Product Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	$ 79,047	$ 71,040	$ 158,837	$ 129,433
Finished Pharmaceutical Products
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	73,735	63,241	148,274	116,358
Finished Pharmaceutical Products | Enoxaparin
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	9,838	8,715	24,322	15,722
Finished Pharmaceutical Products | Naloxone
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	7,833	11,133	15,197	20,060
Finished Pharmaceutical Products | Lidocaine
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	10,082	10,010	22,061	19,792
Finished Pharmaceutical Products | Phytonadione
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	12,441	10,806	22,561	19,987
Finished Pharmaceutical Products | Epinephrine
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	3,139	3,687	5,818	6,910
Finished Pharmaceutical Products | Medroxyprogesterone
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	6,696	6,365	13,909	9,071
Finished Pharmaceutical Products | Primatene Mist
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	2,512		5,409
Finished Pharmaceutical Products | Other Finished Pharmaceutical Products
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Net Revenue	$ 21,194	$ 12,525	$ 38,997	$ 24,816

Segment Reporting (Summary of R

Segment Reporting (Summary of Revenues and Long-Lived Assets by Geographic Region) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Revenue	$ 79,047	$ 71,040	$ 158,837	$ 129,433
Long-Lived Assets	220,060		220,060		$ 210,418
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Revenue	74,781	68,560	151,238	121,664
Long-Lived Assets	106,803		106,803		109,331
CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Revenue	984		984
Long-Lived Assets	68,620		68,620		58,059
FRANCE
Revenues from External Customers and Long-Lived Assets [Line Items]
Net Revenue	3,282	$ 2,480	6,615	$ 7,769
Long-Lived Assets	$ 44,637		$ 44,637		$ 43,028

Customer and Supplier Concent_3

Customer and Supplier Concentration (Details) - Customer Concentration Risk [Member] - item	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
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	3				3
Net Revenues
Revenue, Major Customer [Line Items]
Number of major customers	3	3	3	3
AmerisourceBergen | Accounts Receivable, Net
Revenue, Major Customer [Line Items]
Major Customers			12.00%		19.00%
AmerisourceBergen | Net Revenues
Revenue, Major Customer [Line Items]
Major Customers	25.00%	27.00%	23.00%	26.00%
Cardinal Health | Accounts Receivable, Net
Revenue, Major Customer [Line Items]
Major Customers			20.00%		21.00%
Cardinal Health | Net Revenues
Revenue, Major Customer [Line Items]
Major Customers	21.00%	20.00%	23.00%	21.00%
McKesson | Accounts Receivable, Net
Revenue, Major Customer [Line Items]
Major Customers			28.00%		28.00%
McKesson | Net Revenues
Revenue, Major Customer [Line Items]
Major Customers	25.00%	25.00%	27.00%	26.00%

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Summary of Intangible Assets) (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	6 Months Ended		12 Months Ended
	Jan. 31, 2018	Feb. 28, 2017	Jun. 30, 2017	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2016
Definite-lived intangible assets
Weighted-Average Life (Years)				13 years		12 years
Finite-Lived Intangible Assets, Gross				$ 11,975		$ 39,140
Accumulated Amortization				3,412		30,049
Finite-Lived Intangible Assets, Net				8,563		9,091
Indefinite-lived intangible assets
Goodwill recognized				3,930		3,951	$ 4,461
Subtotal, Original Cost				33,155		33,176
Subtotal, Net Book Value				33,155		33,176
Balance, Original Cost				45,130		72,316
Balance, Net Book Value				41,718		42,267
Proceeds received from sale of ANDAs					$ 4,400
Hikma Pharmaceuticals PLC
Indefinite-lived intangible assets
Sale price of intangible assets								$ 6,400
Proceeds received from sale of ANDAs	$ 4,400	$ 1,000	$ 1,000
Royalty Fee Percentage		2.00%
Gain recognized within operating (income) expenses							$ 2,600
Finished Pharmaceutical Products
Indefinite-lived intangible assets
Goodwill recognized				3,930		3,951
Trademarks
Indefinite-lived intangible assets
Indefinite-lived intangible assets				$ 29,225		$ 29,225
Product rights
Definite-lived intangible assets
Weighted-Average Life (Years)						12 years
Finite-Lived Intangible Assets, Gross						$ 27,134
Accumulated Amortization						$ 27,134
Patents
Definite-lived intangible assets
Weighted-Average Life (Years)				12 years		12 years
Finite-Lived Intangible Assets, Gross				$ 486		$ 486
Accumulated Amortization				234		213
Finite-Lived Intangible Assets, Net				$ 252		$ 273
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				519		486
Finite-Lived Intangible Assets, Net				$ 2,021		$ 2,054
Other intangible assets
Definite-lived intangible assets
Weighted-Average Life (Years)				4 years		4 years
Finite-Lived Intangible Assets, Gross				$ 69		$ 69
Accumulated Amortization				$ 69		63
Finite-Lived Intangible Assets, Net						$ 6
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				$ 8,880		$ 8,911
Accumulated Amortization				2,590		2,153
Finite-Lived Intangible Assets, Net				$ 6,290		$ 6,758

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets (Summary of Changes in the Carrying Amount of Goodwill) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets
Beginning balance	$ 3,951	$ 4,461
Currency translation and other adjustments	(21)	(510)
Ending balance	$ 3,930	$ 3,951

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Inventories
Raw materials and supplies	$ 45,633		$ 45,633		$ 30,153
Work in process	36,224		36,224		30,272
Finished goods	17,375		17,375		8,897
Total inventory, net	99,232		99,232		$ 69,322
Inventory adjustment to reflect net realizable value	$ 2,500	$ 1,200	$ 5,700	$ 3,100

Property, Plant, and Equipmen_2

Property, Plant, and Equipment (Summary of Property, Plant, and Equipment) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	$ 376,325	$ 359,510
Less accumulated depreciation and amortization	(156,265)	(149,092)
Total property, plant, and equipment, net	220,060	210,418
Buildings
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	97,340	96,287
Leasehold improvement
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	29,211	26,755
Land
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	7,619	7,628
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	151,457	143,299
Furniture, fixtures, and automobiles
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	19,982	19,151
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment	$ 70,716	$ 66,390

Accounts Payable and Accrued _3

Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounts Payable and Accrued Liabilities
Accrued customer fees and rebates	$ 11,455	$ 15,215
Accrued payroll and related benefits	20,357	19,430
Accrued product returns, current portion	6,644	5,349
Reserve for net loss on firm purchase commitments	3,403	5,355
Other accrued liabilities	14,850	10,746
Total accrued liabilities	56,709	56,095
Accounts payable	31,462	31,323
Total accounts payable and accrued liabilities	$ 88,171	$ 87,418

Debt (Schedule of Debt) (Detail

Debt (Schedule of Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument
Equipment under Capital Leases		$ 1,055
Equipment under Finance Leases	$ 958
Total debt and capital leases	46,734	50,213
Less current portion of long-term debt and capital leases	6,941	18,229
Long-term debt and finance leases, net of current portion	39,793	31,984
Equipment Loan - Due January 2019 | East West Bank
Debt Instrument
Long Term Debt		128
Mortgage Payable - Due February 2021 | East West Bank
Debt Instrument
Long Term Debt	3,446	3,491
Equipment Loan - Due June 2021 | East West Bank
Debt Instrument
Long Term Debt	2,449	3,061
Equipment Line of Credit - Due December 2022 | East West Bank
Debt Instrument
Long Term Debt	7,000	8,000
Mortgage Payable - Due October 2026 | East West Bank
Debt Instrument
Long Term Debt	3,432	3,463
Mortgage Payable - Due June 2027 | East West Bank
Debt Instrument
Long Term Debt	8,732	8,801
Acquisition Loan - Due June 2024 | Cathay Bank
Debt Instrument
Long Term Debt	11,979	13,025
Mortgage Payable - Due August 2027 | Cathay Bank
Debt Instrument
Long Term Debt	7,540	7,627
Working Capital Loan - Due June 2019 | Bank of Nanjing
Debt Instrument
Long Term Debt		347
French Government Loan - Due June 2020 | Seine-Normandie Water Agency
Debt Instrument
Long Term Debt	26	55
French Government Loan - Due July 2021 | Seine-Normandie Water Agency
Debt Instrument
Long Term Debt	176	172
French Government Loan - Due December 2026 | Seine-Normandie Water Agency
Debt Instrument
Long Term Debt	438	436
Note Payable To Merck
Debt Instrument
Long Term Debt	$ 558	$ 552

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Debt
Proceeds from borrowing under lines of credit	$ 260
Long-term Debt and Capital Lease Obligations			$ 39,793	$ 31,984
Financed lease assets			985
East West Bank
Debt
Interest rate swap, fair value			400	200
Equipment Loan - Due January 2019 | East West Bank
Debt
Long Term Debt				128
Mortgage Payable - Due February 2021 | East West Bank
Debt
Long Term Debt			3,446	3,491
Equipment Loan - Due June 2021 | East West Bank
Debt
Long Term Debt			2,449	3,061
Mortgage Payable - Due October 2026 | East West Bank
Debt
Long Term Debt			3,432	3,463
Mortgage Payable - Due June 2027 | East West Bank
Debt
Long Term Debt			8,732	8,801
Acquisition Loan - Due June 2024 | Cathay Bank
Debt
Long Term Debt			11,979	13,025
Acquisition Loan - Due June 2024 | Cathay Bank | Prime Rate
Debt
Debt Instrument, Interest Rate, Stated Percentage		5.00%
Mortgage Payable - Due August 2027 | Cathay Bank
Debt
Long Term Debt			7,540	7,627
Working Capital Loan - Due June 2019 | Bank of Nanjing
Debt
Long Term Debt				347
Note Payable To Merck
Debt
Long Term Debt			$ 558	$ 552

Income Taxes (Summary of Income

Income Taxes (Summary of Income Before Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income (loss) before income taxes:
Income (loss) before income taxes	$ 61,093	$ (4,200)	$ 57,460	$ (13,089)
Income tax expense (benefit)	14,173	(1,347)	12,694	(3,095)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 46,920	$ (2,853)	$ 44,766	$ (9,994)
Income tax provision as a percentage of income before income taxes	23.20%	32.10%	22.10%	23.60%
Income tax benefit decrease	$ 0		$ 0

Stockholders' Equity (Summary o

Stockholders' Equity (Summary of the Changes in Stockholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stockholders' Equity
Balance	$ 380,266	$ 323,616	$ 364,359	$ 333,736
Beginning balance adjustment as a result of the adoption of new accounting standards			(54)	582
Net income (loss) attributable to Amphastar Pharmaceuticals, Inc.	47,787	(2,853)	48,655	(9,994)
Other comprehensive income (loss) attributable to Amphastar Pharmaceuticals, Inc.	(97)	(2,256)	(210)	(1,066)
Net proceeds from the private placement of ANP			18,966
Net loss attributable to non-controlling interest	(867)		(3,889)
Net proceeds (payments) from equity plans, net of withholding tax payments	2,240	1,499	(157)	(294)
Share-based compensation expense	4,032	4,196	8,706	8,862
Purchase of treasury stock	(1,073)	(7,226)	(4,088)	(14,850)
Balance	$ 432,288	$ 316,976	$ 432,288	$ 316,976

Stockholders' Equity (2014 Empl

Stockholders' Equity (2014 Employee Stock Purchase Plan) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stockholders' Equity
Allocated share based compensation	$ 4,032	$ 4,196	$ 8,706	$ 8,862

Stockholders' Equity (Share Buy

Stockholders' Equity (Share Buyback Program) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	May 06, 2019
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method	$ 1,073	$ 7,226	$ 4,088	$ 14,850
November 2014 Share Repurchase Plan
Equity, Class of Treasury Stock [Line Items]
Increase authorized for share buyback program					$ 20,000
Treasury Stock, Shares, Acquired (in Shares)	50,980	430,137	196,459	837,741
Treasury Stock, Value, Acquired, Cost Method	$ 1,100	$ 7,200	$ 4,100	$ 14,800

Stockholders' Equity (The 2015

Stockholders' Equity (The 2015 Equity Incentive Plan) (Details) - The 2015 Equity Incentive Plan - shares	Jan. 01, 2019	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)		6,137,364
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	1,165,778

Stockholders' Equity (The 2018

Stockholders' Equity (The 2018 ANP Equity Incentive Plan) (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted		1,033,268
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		5 years 1 month 28 days
The 2018 ANP Equity Incentive Plan
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
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	10 years
Share Based Compensation Arrangement By Share Based Payment Award Options Fair Value	$ 2.1
The 2018 ANP Equity Incentive Plan | Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	3,648,932

Stockholders' Equity (Key Assum

Stockholders' Equity (Key Assumptions Used in Determining Fair Value of Options Granted) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stockholders' Equity
Average volatility	43.40%	41.70%	42.50%	39.90%
Risk-free interest rate	2.00%	2.80%	2.40%	2.70%
Weighted-average expected life in years	5 years	4 years 10 months 24 days	5 years 8 months 12 days	5 years 8 months 12 days
Dividend yield rate	0.00%	0.00%	0.00%	0.00%

Stockholders' Equity (Summary_2

Stockholders' Equity (Summary of Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Options
Outstanding Options, Beginning of period			10,105,565
Options granted			1,033,268
Options exercised			(1,074,413)
Options cancelled			(5,219)
Options expired			(2,325)
Outstanding Options, End of period	10,056,876		10,056,876
Exercisable at the end of period	7,311,977		7,311,977
Weighted-Average Exercise Price
Outstanding Exercise Price (in dollars per share)			$ 14.69
Options granted (in dollars per share)			20.96
Options exercised (in dollars per share)			15.60
Options cancelled (in dollars per share)			18.90
Options expired (in dollars per share)			14.65
Outstanding Exercise Price (in dollars per share)	$ 15.23		15.23
Exercisable at the end of period (in dollars per share)	$ 14.18		$ 14.18
Additional Disclosures
Outstanding Contractual Term (in Years)			5 years 1 month 28 days
Outstanding Intrinsic Value	$ 59,792		$ 59,792
Exercisable remaining contractual term (in Years)			4 years 1 month 17 days
Exercisable aggregate intrinsic value	50,760		$ 50,760
Allocated share based compensation	4,032	$ 4,196	8,706	$ 8,862
Employee Stock Option
Additional Disclosures
Allocated share based compensation	$ 1,800	$ 2,000	$ 4,200	$ 4,600

Stockholders' Equity (Informati

Stockholders' Equity (Information Relating to Option Grants and Exercises) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stockholders' Equity
Weighted-average grant date fair value (in Dollars per share)	$ 8.17	$ 6.53	$ 8.46	$ 7.79
Intrinsic value of options exercised	$ 452	$ 277	$ 5,822	$ 1,338
Cash received	1,108	650	5,047	2,511
Total fair value of the options vested during the year	$ 388	$ 1,383	$ 7,502	$ 7,790

Stockholders' Equity (Summary_3

Stockholders' Equity (Summary of Nonvested Options) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Options
Nonvested at beginning of period			3,279,026
Options granted			1,033,268
Options vested			(1,562,176)
Options forfeited			(5,219)
Nonvested at end of period	2,744,899		2,744,899
Weighted-Average Grant Date Fair Value
Nonvested at beginning of period (in dollars per share)			$ 5.47
Options granted (in dollars per share)	$ 8.17	$ 6.53	8.46	$ 7.79
Options vested (in dollars per share)			4.80
Options forfeited (in dollars per share)			8.12
Nonvested at end of period (in dollars per share)	$ 6.97		$ 6.97
Employee Consultant And Directors Stock Options
Weighted-Average Grant Date Fair Value
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options	$ 15.2		$ 15.2
Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			2 years 6 months

Stockholders' Equity (Restricte

Stockholders' Equity (Restricted Stock Units) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding Contractual Term (in Years)			5 years 1 month 28 days
Allocated share based compensation	$ 4,032	$ 4,196	$ 8,706	$ 8,862
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	$ 2,000	$ 2,000	$ 4,100	$ 3,900
Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			2 years 6 months
Share-based Compensation Arrangement by Share-based Payment Award, Restricted Stock Units, Number of Shares of Common Stock Per Award (in Shares)	1		1
Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options	$ 16,500		$ 16,500

Stockholders' Equity (Informa_2

Stockholders' Equity (Information Relating to RSU Grants and Deliveries) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)shares
Restricted Stock Units (RSUs)
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	1,206,661
RSUs granted	431,697
RSUs forfeited	(2,976)
RSUs vested	(530,506)
Total RSUs outstanding at the end of the period	1,104,876
Stock surrendered to fulfill tax withholding obligations	233,539
Restricted Stock Units Issued as Compensation
Total Fair Market Value of RSUs Issued
RSUs granted (in Dollars) | $	$ 8,733

Stockholders' Equity (Share-Bas

Stockholders' Equity (Share-Based Compensation Expense Included in the Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	$ 4,032	$ 4,196	$ 8,706	$ 8,862
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	959	981	2,238	2,141
Selling, distribution and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	95	104	189	211
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	2,648	2,743	5,439	5,636
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation	$ 330	$ 368	$ 840	$ 874

Employee Benefits (Details)

Employee Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	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	$ 0.4	$ 0.3	$ 0.7	$ 0.6
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	0.90%		0.90%		1.70%
Defined Benefit Plan, Benefit Obligation	$ 2.2		$ 2.2		$ 2.2
Pension Cost			$ 0.1	$ 0.1

Commitments and Contingencies_2

Commitments and Contingencies (Lease Expense) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Right-of-use assets	$ 20,143	$ 20,143
Lease obligations	20,491	20,491
Operating lease cost	902	1,790
Short-term lease costs	177	307
Amortization of right-of-use assets	88	171
Interest on lease liabilities	12	24
Total financed lease cost	100	195
Total lease costs	$ 1,179	$ 2,292
Minimum
Lessee, Lease, Description [Line Items]
Lease renewal term	1 year	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lease renewal term	6 years	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_3

Commitments and Contingencies (Lease Cash Flow Information) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)
Commitments and Contingencies
Operating cash flows from operating Leases	$ 1,648
Operating cash flows from finance leases	24
Financing cash flows from finance leases	171
Right-of use assets obtained in exchange for lease obligations: Operating leases	7,663
Right-of use assets obtained in exchange for lease obligations: Finance leases	$ 61
Weighted-average remaining lease term (years), Operating leases	8 years 4 months 24 days
Weighted-average remaining lease term (years), Finance leases	2 years 10 months 24 days
Weighted-average discount rate, Operating leases	5.90%
Weighted-average discount rate, Finance leases	4.60%

Commitments and Contingencies_4

Commitments and Contingencies (Future Minimum Rental Payments) (Details) $ in Thousands	Jun. 30, 2019USD ($)
Operating Leases
2019 (excluding the six months ended June 30, 2019)	$ 1,844
2020	4,111
2021	4,335
2022	3,651
2023	2,429
Thereafter	10,167
Total lease payments	26,537
Less: interest	6,046
Total	20,491
Finance Leases
2019 (excluding the six months ended June 30, 2019)	163
2020	375
2021	298
2022	175
2023	14
Thereafter	6
Total lease payments	1,031
Less: interest	73
Total	958
Total
2019 (excluding the six months ended June 30, 2019)	2,007
2020	4,486
2021	4,633
2022	3,826
2023	2,443
Thereafter	10,173
Total lease payments	27,568
Less: interest	6,119
Total	$ 21,449

Commitments and Contingencies_5

Commitments and Contingencies (Purchase Commitments) (Details) - USD ($) $ in Millions	1 Months Ended		6 Months Ended
	Nov. 30, 2012	Jan. 31, 2010	Jun. 30, 2019
Commitments to Purchase Equipment and Raw Materials
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Long-term Purchase Commitment, Amount			$ 55.1
Land-use rights | Commitment to invest
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Finite-lived Intangible Assets Acquired	$ 1.3	$ 1.2
Land-use rights | Commitment to develop land
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Contractual Obligation	$ 15
Payments for Construction in Process			$ 8.3

Related-Party Transactions (Det

Related-Party Transactions (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
	Jul. 31, 2018	Mar. 31, 2019	Jun. 30, 2019
Related Party Transaction [Line Items]
Proceeds from private placement			$ 18,298
ANP
Related Party Transaction [Line Items]
Proceeds from private placement		$ 56,300
Proceeds from private placement	$ 57,000
ANP | Management and directors
Related Party Transaction [Line Items]
Proceeds from private placement	$ 29,700

Litigation (Details)

Litigation (Details) $ in Millions	Jun. 27, 2019USD ($)	Sep. 30, 2011item
Pending Litigation [Member] | Enoxaparin Patent Litigation
Loss Contingencies [Line Items]
Number of Alleged Patent Infringements | item		2
Settled Litigation [Member]
Loss Contingencies [Line Items]
Litigation Settlement, amount paid to the Company | $	$ 59.9

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - MannKind Corporation $ in Thousands	1 Months Ended
	Aug. 31, 2019USD ($)
Subsequent Events
Long-term Supply Commitment, Optional Renewal Period	2 years
Amendment fee receivable	$ 2,750
Amount due in September, 2019
Subsequent Events
Amendment fee receivable	$ 1,500