BioMarin Pharmaceutical (BMRN) 10-Q 1 May 20 2020 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2020	Apr. 20, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	000-26727
Entity Registrant Name	BioMarin Pharmaceutical Inc
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	68-0397820
Entity Address, Address Line One	770 Lindaro Street
Entity Address, City or Town	San Rafael
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94901
City Area Code	415
Local Phone Number	506-6700
Title of 12(b) Security	Common Stock, par value $0.001
Trading Symbol	BMRN
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		180,836,856
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001048477
Current Fiscal Year End Date	--12-31

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	[1]
Current assets:
Cash and cash equivalents	$ 476,632	$ 437,446
Short-term investments	381,764	316,361
Accounts receivable, net	396,384	377,404
Inventory	705,652	680,275
Other current assets	155,817	130,657
Total current assets	2,116,249	1,942,143
Noncurrent assets:
Long-term investments	290,796	411,978
Property, plant and equipment, net	1,009,972	1,010,868
Intangible assets, net	443,717	456,580
Goodwill	196,199	197,039
Deferred tax assets	539,990	549,422
Other assets	125,918	122,009
Total assets	4,722,841	4,690,039
Current liabilities:
Accounts payable and accrued liabilities	454,506	570,621
Short-term convertible debt, net	365,964	361,882
Total current liabilities	820,470	932,503
Noncurrent liabilities:
Long-term convertible debt, net	486,713	486,238
Long-term contingent consideration	50,524	50,793
Other long-term liabilities	125,172	98,124
Total liabilities	1,482,879	1,567,658
Stockholders’ equity:
Common stock, $0.001 par value: 500,000,000 shares authorized; 180,761,969 and 179,383,114 shares issued and outstanding, respectively.	181	180
Additional paid-in capital	4,854,814	4,832,707
Company common stock held by Nonqualified Deferred Compensation Plan (the NQDC)	(9,832)	(9,961)
Accumulated other comprehensive income	34,127	20,164
Accumulated deficit	(1,639,328)	(1,720,709)
Total stockholders’ equity	3,239,962	3,122,381	[2]
Total liabilities and stockholders’ equity	$ 4,722,841	$ 4,690,039
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.
[2]	The beginning balances were derived from the audited Consolidated Financial Statements included in Company’s Annual Report on Form 10-K for the years ended December 31, 2019 and 2018, respectively, filed with the SEC on February 27, 2020.

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	180,761,969	179,383,114
Common stock, shares outstanding (in shares)	180,761,969	179,383,114

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
REVENUES:
Total revenues	$ 502,069	$ 400,745
OPERATING EXPENSES:
Cost of sales	111,374	89,182
Research and development	142,257	183,591
Selling, general and administrative	187,295	162,158
Intangible asset amortization and contingent consideration	15,677	19,765
Gain on sale of nonfinancial assets	(59,495)	0
Total operating expenses	397,108	454,696
INCOME (LOSS) FROM OPERATIONS	104,961	(53,951)
Equity in the loss of BioMarin/Genzyme LLC	(77)	(185)
Interest income	5,244	6,298
Interest expense	(6,915)	(6,727)
Other income (expense), net	(1,861)	1,608
INCOME (LOSS) BEFORE INCOME TAXES	101,352	(52,957)
Provision for income taxes	19,971	3,516
NET INCOME (LOSS)	$ 81,381	$ (56,473)
NET INCOME (LOSS) PER SHARE, BASIC (in dollars per share)	$ 0.45	$ (0.32)
NET INCOME (LOSS) PER SHARE, DILUTED (in dollars per share)	$ 0.44	$ (0.32)
Weighted average common shares outstanding, basic (in shares)	179,898	178,271
Weighted average common shares outstanding, diluted (in shares)	187,163	178,271
COMPREHENSIVE INCOME (LOSS)	$ 95,344	$ (41,950)
Net product revenues
REVENUES:
Total revenues	489,043	394,483
Royalty and other revenues
REVENUES:
Total revenues	$ 13,026	$ 6,262

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands		Total		Common Stock	Additional Paid-in Capital	Company Stock Held By NQDC	Accumulated other comprehensive income (loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2018	[1]			178,253,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				780,000
Ending balance (in shares) at Mar. 31, 2019				179,033,000
Beginning Balance at Dec. 31, 2018	[1]	$ 2,967,940		$ 178	$ 4,669,926	$ (13,301)	$ 5,271	$ (1,694,134)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				1	(28,732)
Stock-based compensation					41,706
Common stock held by the NQDC					0	389
Other comprehensive income							14,523
Net income (loss)		(56,473)						(56,473)
Ending Balance at Mar. 31, 2019		2,936,627		$ 179	4,682,900	(12,912)	19,794	(1,753,334)
Beginning balance (in shares) at Dec. 31, 2019	[1]			179,838,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				924,000
Ending balance (in shares) at Mar. 31, 2020				180,762,000
Beginning Balance at Dec. 31, 2019	[1]	3,122,381	[2]	$ 180	4,832,707	(9,961)	20,164	(1,720,709)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				1	(24,227)
Stock-based compensation					46,463
Common stock held by the NQDC					(129)	129
Other comprehensive income							13,963
Net income (loss)		81,381						81,381
Ending Balance at Mar. 31, 2020		$ 3,239,962		$ 181	$ 4,854,814	$ (9,832)	$ 34,127	$ (1,639,328)
[1]	The beginning balances were derived from the audited Consolidated Financial Statements included in Company’s Annual Report on Form 10-K for the years ended December 31, 2019 and 2018, respectively, filed with the SEC on February 27, 2020.
[2]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020		Mar. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 81,381		$ (56,473)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	25,964		22,427
Non-cash interest expense	4,618		4,409
(Accretion of discount) Amortization of premium on investments	60		(891)
Stock-based compensation	46,994		42,761
Gain on sale of nonfinancial assets	(59,495)		0
Deferred income taxes	10,603		(704)
Unrealized foreign exchange (gain) loss	9,400		(419)
Non-cash changes in the fair value of contingent consideration	(4)		12,260
Other	(383)		(19)
Changes in operating assets and liabilities:
Accounts receivable, net	(31,898)		(51,690)
Inventory	(20,706)		1,735
Other current assets	8,302		10,112
Other assets	(441)		2,220
Accounts payable and accrued liabilities	(94,733)		(42,070)
Other long-term liabilities	5,144		1,474
Net cash used in operating activities	(15,194)		(54,868)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant and equipment	(40,554)		(28,756)
Maturities and sales of investments	94,701		219,894
Purchases of available-for-sale securities	(40,104)		(239,843)
Proceeds from sale of nonfinancial assets	67,159		0
Purchase of intangible assets	(3,463)		(1,706)
Other	(335)		(68)
Net cash provided by (used in) investing activities	77,404		(50,479)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercises of awards under equity incentive plans	10,116		5,798
Taxes paid related to net share settlement of equity awards	(28,844)		(30,105)
Principal repayments of financing leases	(943)		(674)
Net cash used in financing activities	(19,671)		(24,981)
Effect of exchange rate changes on cash	(3,353)		715
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	39,186		(129,613)
Cash and cash equivalents:
Beginning of period	437,446	[1]	493,982
End of period	476,632		364,369
SUPPLEMENTAL CASH FLOW DISCLOSURES:
Cash paid for income taxes	2,267		906
Cash paid for interest	1,403		1,483
SUPPLEMENTAL CASH FLOW DISCLOSURES FOR NON-CASH INVESTING AND FINANCING ACTIVITIES:
Decrease in accounts payable and accrued liabilities related to fixed assets	$ (19,927)		$ (3,502)
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.

NATURE OF OPERATIONS

NATURE OF OPERATIONS	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
NATURE OF OPERATIONS	NATURE OF OPERATIONS BioMarin Pharmaceutical Inc. (the Company) is a global biotechnology company that develops and commercializes innovative therapies for people with serious and life-threatening rare diseases and medical conditions. The Company selects product candidates for diseases and conditions that represent a significant unmet medical need, have well-understood biology and provide an opportunity to be first-to-market or offer a significant benefit over existing products. The Company’s portfolio consists of several commercial therapies and multiple clinical and preclinical product candidates. The Company expects to continue to finance future cash needs that exceed its operating activities primarily through its current cash, cash equivalents and investments and through proceeds from debt or equity offerings, commercial borrowing, or through collaborative agreements with corporate partners. If the Company elects to increase its spending on development programs significantly above current long-term plans or enters into potential licenses and other acquisitions of complementary technologies, products or companies, the Company may need additional capital.

BASIS OF PRESENTATION

BASIS OF PRESENTATION	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION The accompanying Condensed Consolidated Financial Statements have been prepared pursuant to United States (U.S.) generally accepted accounting principles (U.S. GAAP) and the rules and regulations of the SEC for Quarterly Reports on Form 10-Q and do not include all of the information and note disclosures required by U.S. GAAP for complete financial statements, although the Company believes that the disclosures herein are adequate to ensure that the information presented is not misleading. The Condensed Consolidated Financial Statements should therefore be read in conjunction with the Consolidated Financial Statements and Notes thereto for the fiscal year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K. The results of operations for the three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020 or any other period. On January 1, 2020, the Company adopted Financial Accounting Standards Board (FASB) Accounting Standards Update (ASU) No. 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments (ASU 2016-13), as amended, using a modified retrospective approach. The standard has amended the guidance for measuring and recording credit losses on financial assets measured at amortized cost by replacing the incurred-loss model with an expected-loss model. This new standard also requires that credit losses related to available-for-sale debt securities be recorded as an allowance through net income rather than by reducing the carrying amount under the current, other-than-temporary impairment model. Results for reporting periods beginning January 1, 2020 are presented under ASU 2016-13 and the adoption of this standard had no impact on the Company’s Financial Statements. U.S. GAAP requires management to make estimates and assumptions that affect amounts reported in the Condensed Consolidated Financial Statements and accompanying disclosures. Although these estimates are based on management’s best knowledge of current events and actions that the Company may undertake in the future, actual results may be different from those estimates. The Condensed Consolidated Financial Statements reflect all adjustments of a normal, recurring nature that are, in the opinion of management, necessary for a fair presentation of results for these interim periods. The full extent to which the novel coronavirus disease (referred to as COVID-19) pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including revenues, expenses, reserves and allowances, manufacturing, clinical trials and research and development costs, will depend on future developments that are highly uncertain at this time. As events continue to evolve and additional information becomes available, the Company’s estimates may change materially in future periods. Management performed an evaluation of the Company’s activities through the date of filing of this Quarterly Report on Form 10-Q, and has concluded that there were no subsequent events or transactions that occurred subsequent to the balance sheet date prior to filing this Quarterly Report on Form 10-Q that would require recognition or disclosure in the Condensed Consolidated Financial Statements.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Except as detailed below, there have been no material changes to the Company’s significant accounting policies during the three months ended March 31, 2020, as compared to the significant accounting policies disclosed in Note 3 – Significant Accounting Policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Marketable Securities The Company determines the appropriate classification of its investments in debt and equity securities at the time of purchase and reevaluates such designations at each reporting period. The Company classifies its debt and equity securities with

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	3 Months Ended
	Mar. 31, 2020
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS Except as described in Note 2 – Basis of Presentation , there have been no new accounting pronouncements adopted by the Company or new accounting pronouncements issued by the FASB during the three months ended March 31, 2020, as compared to the recent accounting pronouncements described in Note 4 of the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, that the Company believes are of significance or potential significance to the Company.

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
FINANCIAL INSTRUMENTS	FINANCIAL INSTRUMENTS All marketable securities were classified as available-for-sale at March 31, 2020 and December 31, 2019. The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category for each period presented: March 31, 2020 Amortized Cost Gross Gross Aggregate Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 287,756 $ — $ — $ 287,756 $ 287,756 $ — $ — Level 2: Money market instruments 188,876 — — 188,876 188,876 — — Corporate debt securities 475,439 1,450 (1,888) 475,001 — 286,894 188,107 U.S. government agency securities 181,818 3,561 185,379 — 92,597 92,782 Asset-backed securities 11,454 59 (33) 11,480 — 2,273 9,207 Foreign and other 549 152 (1) 700 — 700 Subtotal 858,136 5,222 (1,922) 861,436 188,876 381,764 290,796 Total $ 1,145,892 $ 5,222 $ (1,922) $ 1,149,192 $ 476,632 $ 381,764 $ 290,796 (1) The Company’s short-term marketable securities mature in one year or less. (2) The Company’s long-term marketable securities mature between one As of March 31, 2020, the Company has the ability and intent to hold all investments that were in an unrealized loss position until maturity or recovery. The Company considered the extent to which fair value is less than amortized cost basis, conditions specifically related to the security’s industry and geography, payment structure and history and changes to the ratings (if any) in determining that the decline in fair value compared to carrying value is not related to a credit loss. December 31, 2019 Amortized Cost Gross Gross Aggregate Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 259,347 $ — $ — $ 259,347 $ 259,347 $ — $ — Level 2: Money market instruments 173,100 — — 173,100 173,100 — — Corporate debt securities 518,523 3,575 (12) 522,086 — 233,294 288,792 U.S. government agency securities 209,633 993 (67) 210,559 4,999 83,067 122,493 Foreign and other 549 145 (1) 693 — — 693 Subtotal 901,805 4,713 (80) 906,438 178,099 316,361 411,978 Total $ 1,161,152 $ 4,713 $ (80) $ 1,165,785 $ 437,446 $ 316,361 $ 411,978 (1) The Company’s short-term marketable securities mature in one year or less. (2) The Company’s long-term marketable securities mature between one

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS Intangible assets consisted of the following: March 31, December 31, Intangible assets: Finite-lived intangible assets $ 623,972 $ 652,734 Accumulated amortization (180,255) (196,154) Net carrying value $ 443,717 $ 456,580 In January 2020, the Company completed the sale of worldwide rights to Firdapse, the Company's commercial product for the treatment of Lambert-Eaton myasthenic syndrome, to a third party in exchange for a one-time cash payment of $67.2 million plus residual royalties. Under the terms of the agreement, the Company agreed to provide certain transition services to the third-party purchaser, such as customer sales and support, for up to 12 months after the closing of the transaction. During the first quarter of 2020, the Company recognized a net before-tax gain of $59.5 million related to the sale of the Firdapse intellectual property and existing inventory. Additionally, the Company recognized a $0.8 million reduction to goodwill and disposed of $32.2 million in intangible assets, including related accumulated amortization of $31.6 million, as a result of the sale of Firdapse.

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	3 Months Ended
	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	(7) PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment, net consisted of the following: March 31, December 31, Building and improvements $ 727,272 $ 725,906 Manufacturing and laboratory equipment 376,035 366,951 Computer hardware and software 170,132 167,554 Leasehold improvements 51,323 51,324 Furniture and equipment 38,124 38,569 Land improvements 7,349 7,349 Land 90,418 90,418 Construction-in-progress 119,328 111,897 1,579,981 1,559,968 Accumulated depreciation (570,009) (549,100) Total property, plant and equipment, net $ 1,009,972 $ 1,010,868 The construction-in-progress balance primarily included costs related to significant in-progress projects at the Company's facilities in Marin County, California, and Shanbally, Ireland.

SUPPLEMENTAL BALANCE SHEET INFO

SUPPLEMENTAL BALANCE SHEET INFORMATION	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
SUPPLEMENTAL BALANCE SHEET INFORMATION	SUPPLEMENTAL BALANCE SHEET INFORMATION Inventory consisted of the following: March 31, December 31, Raw materials $ 82,207 $ 74,442 Work-in-process 371,963 349,978 Finished goods 251,482 255,855 Total inventory $ 705,652 $ 680,275 Inventory as of March 31, 2020, included manufacturing-related costs for the commercial production of valoctocogene roxaparvovec inventory totaling $52.5 million. Valoctocogene roxaparvovec is an investigational gene therapy product candidate for the treatment of severe hemophilia A. The Company must receive marketing approval from the applicable regulators before the valoctocogene roxaparvovec inventory can be sold commercially. The Company believes that all material uncertainties related to the ultimate regulatory approval of valoctocogene roxaparvovec for commercial sale have been significantly reduced. A number of factors were taken into consideration, including the current status in the drug development process, pivotal clinical trial results for the underlying product candidate, results from meetings with the relevant regulatory authorities prior to the filing of regulatory applications, historical experience, as well as potential impediments to the approval process such as product safety or efficacy, as well as commercialization and marketplace trends. If regulatory approval is not obtained, the manufacturing-related costs for the commercial production of valoctocogene roxaparvovec will be expensed to Research and Development (R&D). Accounts Payable and Accrued Liabilities consisted of the following: March 31, December 31, 2019 Accounts payable and accrued operating expenses $ 235,163 $ 240,981 Accrued compensation expense 95,148 192,467 Accrued rebates payable 63,917 57,163 Accrued royalties payable 20,331 30,797 Deferred revenue 7,889 13,037 Value added taxes payable 8,444 8,395 Forward foreign currency exchange contracts 7,675 10,448 Lease liabilities 10,401 10,700 Other 5,538 6,633 Total accounts payable and accrued liabilities $ 454,506 $ 570,621

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Company measures certain financial assets and liabilities at fair value in accordance with the policy described in Note 3 – Significant Accounting Policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. The following tables present the classification within the fair value hierarchy of financial assets and liabilities not disclosed elsewhere in these Condensed Consolidated Financial Statements that are remeasured on a recurring basis as of March 31, 2020 and December 31, 2019. There were no financial assets or liabilities that were remeasured using a quoted price in active markets for identical assets (Level 1) as of March 31, 2020. Fair Value Measurements at March 31, 2020 Significant Other Significant Total Assets: Other current assets: NQDC Plan assets $ 367 $ — $ 367 Other assets: NQDC Plan assets 14,917 — 14,917 Restricted investments (1) 4,554 — 4,554 Total other assets 19,471 — 19,471 Total assets $ 19,838 $ — $ 19,838 Liabilities: Current liabilities: NQDC Plan liability $ 367 $ — $ 367 Other long-term liabilities: NQDC Plan liability 14,917 — 14,917 Contingent consideration — 50,524 50,524 Total other long-term liabilities 14,917 50,524 65,441 Total liabilities $ 15,284 $ 50,524 $ 65,808 Fair Value Measurements at December 31, 2019 Significant Other Significant Total Assets: Other current assets: NQDC Plan assets $ 1,177 $ — $ 1,177 Other assets: NQDC Plan assets 16,288 — 16,288 Restricted investments (1) 3,168 — 3,168 Total other assets 19,456 — 19,456 Total assets $ 20,633 $ — $ 20,633 Liabilities: Current liabilities: NQDC Plan liability $ 1,177 $ — $ 1,177 Other long-term liabilities: NQDC Plan liability 16,288 — 16,288 Contingent consideration — 50,793 50,793 Total other long-term liabilities 16,288 50,793 67,081 Total liabilities $ 17,465 $ 50,793 $ 68,258 (1) The restricted investments at March 31, 2020 and December 31, 2019 secure the Company's irrevocable standby letters of credit obtained in connection with certain commercial agreements. There were no transfers between levels during the three months ended March 31, 2020. The following table represents a roll forward of contingent consideration. Contingent consideration at December 31, 2019 $ 50,793 Changes in fair value of contingent consideration (4) Foreign exchange remeasurement of Euro denominated contingent acquisition consideration (265) Contingent consideration at March 31, 2020 $ 50,524

DERIVATIVE INSTRUMENTS AND HEDG

DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES	3 Months Ended
	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES	DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES The Company uses forward foreign currency exchange contracts (forward contracts) to hedge certain operational exposures resulting from potential changes in foreign currency exchange rates. Such exposures result from portions of the Company’s forecasted revenues and operating expenses being denominated in currencies other than the U.S. Dollar (USD), primarily the Euro. The Company designates certain of these forward contracts as hedging instruments and also enters into forward contracts that are considered to be economic hedges that are not designated as hedging instruments. Whether designated or undesignated, these forward contracts protect against the reduction in value of forecasted foreign currency cash flows resulting from product revenues, royalty revenues, operating expenses and asset or liability positions designated in currencies other than the USD. To receive hedge accounting treatment, cash flow hedges must be highly effective in offsetting changes to expected future cash flows on hedged transactions. The Company does not hold or issue derivative instruments for trading or speculative purposes. The maximum length of time over which the Company is hedging its exposure to the reduction in value of forecasted foreign currency revenues through forward contracts is through March 2023. The following table summarizes the Company’s derivatives designated as hedging instruments outstanding as of March 31, 2020 (notional amounts in millions): Foreign Exchange Contracts Number of Aggregate Notional Maturity Purchase: Euros 137 165.4 Apr 2020 - Mar 2023 Sell: Australian Dollars 36 12.8 Apr 2020 - Mar 2021 Canadian Dollars 50 41.2 Apr 2020 - Mar 2021 Colombian Pesos 27 93,150.0 Apr 2020 - Mar 2021 Euros 374 605.3 Apr 2020 - Mar 2023 Norwegian Krone 36 82.0 Apr 2020 - Mar 2021 Total 660 The following table summarizes the Company’s derivatives not designated as hedging instruments outstanding as of March 31, 2020 (notional amounts in millions): Foreign Exchange Contracts Number of Aggregate Notional Maturity Purchase: Euros 1 4.1 Jun 2020 Great British Pounds 1 8.3 Jun 2020 Sell: Colombian Pesos 1 49,800.0 Jun 2020 Rubles 1 1,055.0 Jun 2020 Total 4 The fair value carrying amounts of the Company’s derivatives, as classified within the fair value hierarchy, were as follows: Balance Sheet Location March 31, 2020 December 31, 2019 Derivatives designated as hedging instruments: Asset Derivatives - Level 2 (1) Other current assets $ 30,077 $ 19,584 Other assets 16,984 13,539 Subtotal $ 47,061 $ 33,123 Liability Derivatives - Level 2 (1) Accounts payable and accrued liabilities $ 7,522 $ 8,184 Other long-term liabilities 5,790 5,493 Subtotal $ 13,312 $ 13,677 Derivatives not designated as hedging instruments: Asset Derivatives - Level 2 (1) Other current assets $ 200 $ 469 Liability Derivatives - Level 2 (1) Accounts payable and accrued liabilities $ 153 $ 2,264 Total Derivatives Assets $ 47,261 $ 33,592 Total Derivatives Liabilities $ 13,465 $ 15,941 (1) For additional discussion of fair value measurements, see Note 3 – Summary of Significant Accounting Policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. The following tables summarize the impact of gains and losses from the Company's derivatives on its Condensed Consolidated Statements of Comprehensive Income (Loss) for the periods presented. Three Months Ended Derivatives Designated as Cash Flow Hedging Instruments March 31, 2020 March 31, 2019 Amount of Gain (Loss) Recognized in Other Comprehensive Income $ 19,630 $ 12,825 Three Months Ended March 31, 2020 March 31, 2019 Derivatives Designated as Cash Flow Hedging Instruments Cash Flow Hedging Gains (Losses) Cash Flow Hedging Gains (Losses) Net product revenues as reported $ 489,043 $ 6,329 $ 394,483 $ 695 Operating expenses as reported $ 397,108 $ (1,673) $ 454,696 $ 271 Derivatives Not Designated as Hedging Instruments Gains (Losses) Recognized in Earnings Gains (Losses) Recognized in Earnings Operating Expenses $ 3,809 $ (2,978) As of March 31, 2020, the Company expects to reclassify unrealized gains of $21.0 million from AOCI to earnings as the forecasted revenue and operating expense transactions occur over the next 12 months.

LEASES

LEASES	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Leases	LEASES The following table presents the Company’s right-of-use (ROU) assets and lease liabilities as of March 31, 2020: Lease Classification Classification March 31, December 31, Assets: Operating Other Assets $ 49,116 $ 49,045 Financing Other Assets 9,703 10,389 Total ROU assets $ 58,819 $ 59,434 Liabilities: Current: Operating Accounts payable and accrued liabilities $ 7,114 $ 7,451 Financing Accounts payable and accrued liabilities 3,287 3,249 Noncurrent: Operating Other long-term liabilities 44,529 44,092 Financing Other long-term liabilities 5,844 6,708 Total lease liabilities $ 60,774 $ 61,500 Maturities of lease liabilities as of March 31, 2020 by fiscal year were as follows: Maturity of Lease Liabilities Operating Financing Total Remainder of 2020 $ 8,814 $ 2,763 $ 11,577 2021 9,441 3,070 12,511 2022 8,749 2,339 11,088 2023 7,805 1,749 9,554 2024 5,995 — 5,995 Thereafter 22,044 — 22,044 Total lease payments 62,848 9,921 72,769 Less: Interest (11,205) (790) (11,995) Present value of lease liabilities $ 51,643 $ 9,131 $ 60,774 Three Months Ended Lease Cost Classification 2020 2019 Operating (1) Operating Expenses $ 2,748 $ 3,080 Financing: Amortization Operating Expenses 707 607 Interest expense Operating Expenses 125 161 Total lease costs $ 3,580 $ 3,848 (1) Includes short-term leases and variable lease costs, both of which were not material in the periods presented. Three Months Ended Other Information 2020 2019 Weighted average remaining lease term (in years): Operating leases 7.6 7.8 Financing leases 3.1 4.0 Weighted average discount rate: Operating leases 5.1 % 5.2 % Financing leases 5.3 % 5.4 % As of March 31, 2020, no operating leases are expected to commence in the remainder of 2020. Three Months Ended Supplemental Cash Flow Information 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Cash used in operating activities: Operating leases $ 1,440 $ 1,600 Financing leases $ 127 $ 161 Cash used in financing activities: Financing leases $ 823 $ 674 ROU assets obtained in exchange for lease obligations: Operating leases $ 2,427 $ 19 Financing leases $ 27 $ 68
Leases	LEASES The following table presents the Company’s right-of-use (ROU) assets and lease liabilities as of March 31, 2020: Lease Classification Classification March 31, December 31, Assets: Operating Other Assets $ 49,116 $ 49,045 Financing Other Assets 9,703 10,389 Total ROU assets $ 58,819 $ 59,434 Liabilities: Current: Operating Accounts payable and accrued liabilities $ 7,114 $ 7,451 Financing Accounts payable and accrued liabilities 3,287 3,249 Noncurrent: Operating Other long-term liabilities 44,529 44,092 Financing Other long-term liabilities 5,844 6,708 Total lease liabilities $ 60,774 $ 61,500 Maturities of lease liabilities as of March 31, 2020 by fiscal year were as follows: Maturity of Lease Liabilities Operating Financing Total Remainder of 2020 $ 8,814 $ 2,763 $ 11,577 2021 9,441 3,070 12,511 2022 8,749 2,339 11,088 2023 7,805 1,749 9,554 2024 5,995 — 5,995 Thereafter 22,044 — 22,044 Total lease payments 62,848 9,921 72,769 Less: Interest (11,205) (790) (11,995) Present value of lease liabilities $ 51,643 $ 9,131 $ 60,774 Three Months Ended Lease Cost Classification 2020 2019 Operating (1) Operating Expenses $ 2,748 $ 3,080 Financing: Amortization Operating Expenses 707 607 Interest expense Operating Expenses 125 161 Total lease costs $ 3,580 $ 3,848 (1) Includes short-term leases and variable lease costs, both of which were not material in the periods presented. Three Months Ended Other Information 2020 2019 Weighted average remaining lease term (in years): Operating leases 7.6 7.8 Financing leases 3.1 4.0 Weighted average discount rate: Operating leases 5.1 % 5.2 % Financing leases 5.3 % 5.4 % As of March 31, 2020, no operating leases are expected to commence in the remainder of 2020. Three Months Ended Supplemental Cash Flow Information 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Cash used in operating activities: Operating leases $ 1,440 $ 1,600 Financing leases $ 127 $ 161 Cash used in financing activities: Financing leases $ 823 $ 674 ROU assets obtained in exchange for lease obligations: Operating leases $ 2,427 $ 19 Financing leases $ 27 $ 68

DEBT

DEBT	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
DEBT	DEBT Convertible Notes As of March 31, 2020, the Company had outstanding fixed-rate notes with varying maturities for an undiscounted aggregate principal amount of $870.0 million (collectively the Notes). The Notes are senior subordinated convertible obligations, and interest is payable in arrears, semi-annually. The following table summarizes information regarding the Company’s convertible debt: March 31, December 31, 1.50% senior subordinated convertible notes due in October 2020 (the 2020 Notes) $ 374,993 $ 374,993 Unamortized discount (8,322) (12,078) Unamortized deferred offering costs (707) (1,033) Convertible Notes due in 2020, net (1) 365,964 361,882 0.599% senior subordinated convertible notes due in August 2024 (the 2024 Notes) 495,000 495,000 Unamortized discount (6,179) (6,533) Unamortized deferred offering costs (2,108) (2,229) Convertible Notes due in 2024, net 486,713 486,238 Total convertible debt, net $ 852,677 $ 848,120 Fair value of fixed rate convertible debt (2) : Convertible Notes due in October 2020 401,081 405,679 Convertible Notes due in August 2024 513,147 521,839 Total fair value of fixed rate convertible debt $ 914,228 $ 927,518 (1) The 2020 Notes are classified as a current liability in the periods presented since they mature in October 2020. (2) The fair value of the Company’s fixed-rate convertible debt is based on open market trades and is classified as Level 1 in the fair value hierarchy. For additional discussion of fair value measurements, see Note 3 – Summary of Significant Accounting Policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Interest expense on the Company’s convertible debt consisted of the following: Three Months Ended 2020 2019 Coupon interest expense $ 2,172 $ 2,157 Amortization of debt issuance costs 508 507 Accretion of discount on convertible notes 4,110 3,902 Total interest expense on convertible debt $ 6,790 $ 6,566 See Note 13 - Debt in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 for additional information related to the Company’s convertible debt. Revolving Credit Facility In October 2018, the Company entered into an unsecured revolving credit facility of up to $200.0 million (the 2018 Credit Facility). The 2018 Credit Facility includes a letter of credit subfacility and a swingline loan subfacility and is intended to finance ongoing working capital needs and for other general corporate purposes. Borrowings under the 2018 Credit Facility bear interest, at the Company’s option, at a rate equal to either (a) the LIBOR rate (except that if LIBOR is less than zero it shall be deemed to be zero for purposes of the 2018 Credit Facility), or LIBOR successor rate, plus an applicable margin ranging from 1.00% to 1.95% per annum, based upon the Company’s net leverage ratio and earnings before interest, taxes, depreciation and amortization (EBITDA) for each of the two most recently ended four-quarter measurement periods, or (b) the Base Rate, generally the prime lending rate, plus an applicable margin ranging from 0.00% to 0.95%, based upon the Company’s net leverage ratio and EBITDA for each of the two most recently ended four-quarter measurement periods. Commitment fees payable on the undrawn amount range from 0.15% to 0.35% per annum based upon the Company’s net leverage ratio and EBITDA for each of the two most recently ended four-quarter measurement periods. The Company’s obligations under the Credit Facility are guaranteed by its direct subsidiary, California Corporate Center Acquisition LLC, and such obligations may in the future be guaranteed from time to time by certain other material domestic subsidiaries. The 2018 Credit Facility matures on October 19, 2021 at which time all outstanding amounts become due and payable, except that if at least $100.0 million aggregate principal amount of the 2020 Notes remain outstanding on August 1, 2020 and certain other conditions have not been met, the Company may be required to repay all amounts borrowed under the 2018 Credit Facility on August 1, 2020. The Company incurred approximately $1.0 million of issuance costs, which will be amortized to Interest Expense over the term of the 2018 Credit Facility. The 2018 Credit Facility contains financial covenants requiring the Company to maintain a minimum interest coverage ratio and a minimum liquidity requirement. As of March 31, 2020, and December 31, 2019, there were no outstanding amounts due on nor any usage of the 2018 Credit Facility. As of March 31, 2020, the Company and certain of its subsidiaries that served as guarantors were in compliance with all covenants.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME	ACCUMULATED OTHER COMPREHENSIVE INCOME The following table summarizes amounts reclassified out of AOCI and their effect on the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for the three months ended March 31, 2020 and 2019. Condensed Consolidated Three Months Ended 2020 2019 Gains (losses) on cash flow hedges: Forward contracts Net product revenues $ 6,329 $ 695 Forward contracts Operating expenses (1,673) 271 Total gain (loss) on cash flow hedges $ 4,656 $ 966 The following tables summarize changes in the accumulated balances for each component of AOCI, including current period other comprehensive income (loss) and reclassifications out of AOCI for the three months ended March 31, 2020 and 2019. Three Months Ended March 31, 2020 Unrealized Gains Unrealized Gains Other Total AOCI balance at December 31, 2019 $ 16,614 $ 3,565 $ (15) $ 20,164 Other comprehensive income (loss) before reclassifications 19,630 (1,334) 15 18,311 Less: net gain (loss) reclassified from AOCI 4,656 — 4,656 Tax effect — 308 — 308 Net current-period other comprehensive income (loss) 14,974 (1,026) 15 13,963 AOCI balance at March 31, 2020 $ 31,588 $ 2,539 $ — $ 34,127 Three Months Ended March 31, 2019 Unrealized Gains Unrealized Gains Other Total AOCI balance at December 31, 2018 $ 7,201 $ (1,917) $ (13) $ 5,271 Other comprehensive income (loss) before 12,825 3,455 (1) 16,279 Less: gain (loss) reclassified from AOCI 966 — — 966 Tax effect — (790) — (790) Net current-period other comprehensive income (loss) 11,859 2,665 (1) 14,523 AOCI balance at March 31, 2019 $ 19,060 $ 748 $ (14) $ 19,794

REVENUE, CREDIT CONCENTRATIONS

REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION	3 Months Ended
	Mar. 31, 2020
Concentration Risk And Geographic Information [Abstract]
REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION	REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION The Company operates in one business segment, which primarily focuses on the development and commercialization of innovative therapies for people with serious and life-threatening rare diseases and medical conditions. The Company considers there to be revenue concentration risks for regions where Net Product Revenues exceed 10% of consolidated Net Product Revenues. The concentration of the Company’s Net Product Revenues within the regions below may have a material adverse effect on the Company’s revenues and results of operations if sales in the respective regions experience difficulties. The following table disaggregates Total Revenues from external customers and collaborative partners by geographic region. Net product revenues by geographic region are based on patient location for the Company’s commercial products, except for Aldurazyme, which is sold exclusively to Genzyme Corporation, a wholly owned subsidiary of Sanofi (Genzyme) who markets and sells Aldurazyme world-wide. Aldurazyme revenues earned by the Company are included in the U.S. region as the transactions are with Genzyme whose headquarters is located in the U.S. Three Months Ended 2020 2019 Total revenues by geographic region: United States $ 244,172 $ 190,936 Europe 145,036 124,539 Latin America 59,924 33,839 Rest of world 52,937 51,431 Total revenues $ 502,069 $ 400,745 The following table disaggregates Net Product Revenues by product. Three Months Ended 2020 2019 Net product revenues by product: Brineura $ 23,970 $ 12,180 Firdapse 1,288 5,112 Kuvan 122,028 106,924 Naglazyme 114,256 86,927 Palynziq 34,632 12,272 Vimizim 137,203 125,801 Total net product revenues marketed by the Company $ 433,377 $ 349,216 Aldurazyme net product revenues marketed by Genzyme 55,666 45,267 Total net product revenues $ 489,043 $ 394,483 The table below disaggregates total Net Product Revenues based on patient location for products sold directly by the Company, and global sales of Aldurazyme, which is marketed by Genzyme. Three Months Ended 2020 2019 United States $ 181,671 $ 144,285 Europe 140,851 123,085 Latin America 59,924 33,840 Rest of world 50,931 48,006 Total net product revenues marketed by the Company 433,377 349,216 Aldurazyme net product revenues marketed by Genzyme 55,666 45,267 Total net product revenues $ 489,043 $ 394,483 The following table illustrates the percentage of the Company’s total Net Product Revenues attributed to the Company’s largest customers for the periods presented. Three Months Ended 2020 2019 Customer A 13 % 18 % Customer B 12 % 11 % Customer C 11 % 12 % Customer D 11 % 11 % Total 47 % 52 % On a consolidated basis, two customers accounted for 29% and 14% of the March 31, 2020 accounts receivable balance, respectively, compared to December 31, 2019, when two customers accounted for 24% and 16% of the accounts receivable balance, respectively. As of March 31, 2020, and December 31, 2019, the accounts receivable balance for Genzyme included $86.5 million and $60.2 million, respectively, of unbilled accounts receivable, which become payable to the Company when the product is sold by Genzyme. The Company does not require collateral from its customers but does perform periodic credit evaluations of its customers’ financial condition and requires immediate payment in certain circumstances. The outbreak of COVID-19 will continue to affect economies and business around the world. Although the Company did not see a significant impact on its Net Product Revenues or overall business operations in the first quarter of 2020, ongoing and future effects of COVID-19 (or any future pandemic) on all aspects of its operations, and the duration of such effects, are highly uncertain and difficult to predict. The Company is actively monitoring and managing its response and assessing potential impacts to its operating results and financial condition, as well as adverse developments in its business. The Company is mindful that conditions in the current macroeconomic environment could affect the Company’s ability to achieve its goals. The Company sells its products in countries that face economic volatility and weakness. Although the Company has historically collected receivables from customers in certain countries, sustained weakness or further deterioration of the local economies and currencies and adverse effects of the impact of the ongoing COVID-19 pandemic may cause customers in those countries to be unable to pay for the Company’s products. The Company believes that the allowances for doubtful accounts related to these countries, if any, was adequate based on its analysis of the specific business circumstances and expectations of collection for each of the underlying accounts in these countries. The Company will continue to monitor these conditions and will attempt to adjust its business processes, as appropriate, to mitigate macroeconomic risks to its business.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION The Company has stockholder-approved equity incentive plans that provide for the granting of service-based restricted stock units (RSUs), market-based RSUs, performance-based RSUs, stock options and other types of awards to its employees, officers and non-employee directors. Compensation expense included in the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for all stock-based compensation arrangements was as follows: Three Months Ended March 31, 2020 2019 Cost of sales $ 5,084 $ 4,819 Research and development 13,711 13,833 Selling, general and administrative 28,199 24,109 Total stock-based compensation expense $ 46,994 $ 42,761 Stock-based compensation of $4.6 million and $3.8 million was capitalized into inventory for the three months ended March 31, 2020 and 2019, respectively. Capitalized stock-based compensation is recognized as cost of sales when the related product is sold. Restricted Stock Unit Awards with Market Conditions In March 2020, the Compensation Committee and Board approved the grant of 126,710 RSUs with market-based vesting conditions (base TSR-RSUs) to certain executives. These base TSR-RSUs vest, if at all, in full following a three Restricted Stock Unit Awards with Performance Conditions In March 2020, the Compensation Committee and Board approved the grant of 63,400 RSUs with performance-based vesting conditions (base RSUs) and a grant date fair value of $73.82 per RSU. This award is contingent upon the achievement of a three-year Non-GAAP income target and the awarded RSUs, if any, vest ratably over a three In March 2020, the Compensation Committee and Board approved the grant of 63,400 RSUs with performance-based vesting conditions (base RSUs) and a grant date fair value of $73.82 per RSU. This award is contingent upon the achievement of a three-year strategic goal target and the awarded RSUs, if any, vest ratably over a three

NET INCOME (LOSS) PER COMMON SH

NET INCOME (LOSS) PER COMMON SHARE	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
NET INCOME (LOSS) PER COMMON SHARE	NET INCOME (LOSS) PER COMMON SHARE Potentially issuable shares of common stock include shares issuable upon the exercise of outstanding employee stock option awards, common stock issuable under the Company’s Employee Share Purchase Plan (ESPP), unvested RSUs, common stock held by the NQDC and contingent issuances of common stock related to convertible debt. The following table sets forth the computation of basic and diluted earnings per common share (in thousands of common shares): Three Months Ended March 31, 2020 2019 Numerator: Net Income (Loss), basic $ 81,381 $ (56,473) Add: Interest on 2024 notes 936 — Net Income (Loss), diluted $ 82,317 $ (56,473) Denominator: Weighted-average common shares outstanding, basic 179,898 178,271 Effect of dilutive securities: Options to purchase common stock 1,708 — Common stock issuable under the 2024 notes 3,970 — Unvested RSUs 1,037 — Common stock potentially issuable for ESPP purchases 346 — Common shares held by the NQDC 204 — Weighted-average common shares outstanding, diluted 187,163 178,271 Net Income (Loss) per common share, basic $ 0.45 $ (0.32) Net Income (Loss) per common share, diluted $ 0.44 $ (0.32) In addition to the equity instruments included in the table above, the table below presents potential shares of common stock that were excluded from the computation of diluted earnings per common share as they were anti-dilutive (in thousands): Three Months Ended March 31, 2020 2019 Options to purchase common stock 6,063 7,749 Common stock issuable under the 2020 Notes 3,983 3,983 Common stock issuable under the 2024 Notes — 3,970 Unvested RSUs 3,811 4,164 Common stock potentially issuable for ESPP purchases 232 417 Common stock held by the NQDC — 202 Total number of potentially issuable shares 14,089 20,485 The potential effect of the capped call transactions with respect to the 2020 Notes was excluded from the diluted net income (loss) per share as of March 31, 2020 and 2019, respectively, as the Company’s closing stock price on March 31, 2020 and 2019, respectively, did not exceed the conversion price of $94.15 per share. There is no similar capped call transaction associated with the 2024 Notes. See Note 13 to the Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 for additional information related to the Company’s convertible debt and capped call transaction.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Contingencies From time to time the Company is involved in legal actions arising in the normal course of its business. The process of resolving matters through litigation or other means is inherently uncertain and it is possible that an unfavorable resolution of these matters could adversely affect the Company, its results of operations, financial condition or cash flows. The Company’s general practice is to expense legal fees as services are rendered in connection with legal matters, and to accrue for liabilities when losses are probable and reasonably estimable. Contingent Payments As of March 31, 2020, the Company was subject to contingent payments totaling approximately $355.4 million upon achievement of certain development and regulatory activities and commercial sales milestones, if they occur before certain dates in the future. Of this amount, $66.0 million relates to the acquisition of certain rights and other assets with respect to Kuvan and Palynziq from a third party and $243.1 million relates to programs that are no longer being developed. As of March 31, 2020, the Company recorded a total of $50.5 million of contingent liabilities. See Note 9 to these Condensed Consolidated Financial Statements for further information regarding the fair value of the Company’s contingent consideration. Other Commitments In the normal course of business, the Company enters into various firm purchase commitments primarily related to active pharmaceutical ingredients, certain inventory-related items and certain third-party R&D services. As of March 31, 2020, such commitments and other minimum contractual obligations for clinical and post-marketing services were estimated at approximately $113.4 million.

BASIS OF PRESENTATION (Policies

BASIS OF PRESENTATION (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	The accompanying Condensed Consolidated Financial Statements have been prepared pursuant to United States (U.S.) generally accepted accounting principles (U.S. GAAP) and the rules and regulations of the SEC for Quarterly Reports on Form 10-Q and do not include all of the information and note disclosures required by U.S. GAAP for complete financial statements, although the Company believes that the disclosures herein are adequate to ensure that the information presented is not misleading. The Condensed Consolidated Financial Statements should therefore be read in conjunction with the Consolidated Financial Statements and Notes thereto for the fiscal year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K. The results of operations for the three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020 or any other period. U.S. GAAP requires management to make estimates and assumptions that affect amounts reported in the Condensed Consolidated Financial Statements and accompanying disclosures. Although these estimates are based on management’s best knowledge of current events and actions that the Company may undertake in the future, actual results may be different from those estimates. The Condensed Consolidated Financial Statements reflect all adjustments of a normal, recurring nature that are, in the opinion of management, necessary for a fair presentation of results for these interim periods. The full extent to which the novel coronavirus disease (referred to as COVID-19) pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including revenues, expenses, reserves and allowances, manufacturing, clinical trials and research and development costs, will depend on future developments that are highly uncertain at this time. As events continue to evolve and additional information becomes available, the Company’s estimates may change materially in future periods. Management performed an evaluation of the Company’s activities through the date of filing of this Quarterly Report on Form 10-Q, and has concluded that there were no subsequent events or transactions that occurred subsequent to the balance sheet date prior to filing this Quarterly Report on Form 10-Q that would require recognition or disclosure in the Condensed Consolidated Financial Statements.
Recent Accounting Pronouncements	On January 1, 2020, the Company adopted Financial Accounting Standards Board (FASB) Accounting Standards Update (ASU) No. 2016-13, Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments (ASU 2016-13), as amended, using a modified retrospective approach. The standard has amended the guidance for measuring and recording credit losses on financial assets measured at amortized cost by replacing the incurred-loss model with an expected-loss model. This new standard also requires that credit losses related to available-for-sale debt securities be recorded as an allowance through net income rather than by reducing the carrying amount under the current, other-than-temporary impairment model. Results for reporting periods beginning January 1, 2020 are presented under ASU 2016-13 and the adoption of this standard had no impact on the Company’s Financial Statements.
Marketable Securities	Marketable Securities The Company determines the appropriate classification of its investments in debt and equity securities at the time of purchase and reevaluates such designations at each reporting period. The Company classifies its debt and equity securities with

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Schedule of Cash, Cash Equivalents and Available-for-Sale Securities by Significant Investment Category	The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category for each period presented: March 31, 2020 Amortized Cost Gross Gross Aggregate Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 287,756 $ — $ — $ 287,756 $ 287,756 $ — $ — Level 2: Money market instruments 188,876 — — 188,876 188,876 — — Corporate debt securities 475,439 1,450 (1,888) 475,001 — 286,894 188,107 U.S. government agency securities 181,818 3,561 185,379 — 92,597 92,782 Asset-backed securities 11,454 59 (33) 11,480 — 2,273 9,207 Foreign and other 549 152 (1) 700 — 700 Subtotal 858,136 5,222 (1,922) 861,436 188,876 381,764 290,796 Total $ 1,145,892 $ 5,222 $ (1,922) $ 1,149,192 $ 476,632 $ 381,764 $ 290,796 (1) The Company’s short-term marketable securities mature in one year or less. (2) The Company’s long-term marketable securities mature between one December 31, 2019 Amortized Cost Gross Gross Aggregate Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 259,347 $ — $ — $ 259,347 $ 259,347 $ — $ — Level 2: Money market instruments 173,100 — — 173,100 173,100 — — Corporate debt securities 518,523 3,575 (12) 522,086 — 233,294 288,792 U.S. government agency securities 209,633 993 (67) 210,559 4,999 83,067 122,493 Foreign and other 549 145 (1) 693 — — 693 Subtotal 901,805 4,713 (80) 906,438 178,099 316,361 411,978 Total $ 1,161,152 $ 4,713 $ (80) $ 1,165,785 $ 437,446 $ 316,361 $ 411,978 (1) The Company’s short-term marketable securities mature in one year or less. (2) The Company’s long-term marketable securities mature between one

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	Intangible assets consisted of the following: March 31, December 31, Intangible assets: Finite-lived intangible assets $ 623,972 $ 652,734 Accumulated amortization (180,255) (196,154) Net carrying value $ 443,717 $ 456,580

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	3 Months Ended
	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of Property Plant and Equipment Net	Property, plant and equipment, net consisted of the following: March 31, December 31, Building and improvements $ 727,272 $ 725,906 Manufacturing and laboratory equipment 376,035 366,951 Computer hardware and software 170,132 167,554 Leasehold improvements 51,323 51,324 Furniture and equipment 38,124 38,569 Land improvements 7,349 7,349 Land 90,418 90,418 Construction-in-progress 119,328 111,897 1,579,981 1,559,968 Accumulated depreciation (570,009) (549,100) Total property, plant and equipment, net $ 1,009,972 $ 1,010,868

SUPPLEMENTAL BALANCE SHEET IN_2

SUPPLEMENTAL BALANCE SHEET INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Inventory	Inventory consisted of the following: March 31, December 31, Raw materials $ 82,207 $ 74,442 Work-in-process 371,963 349,978 Finished goods 251,482 255,855 Total inventory $ 705,652 $ 680,275
Schedule of Accounts Payable and Accrued Liabilities	Accounts Payable and Accrued Liabilities consisted of the following: March 31, December 31, 2019 Accounts payable and accrued operating expenses $ 235,163 $ 240,981 Accrued compensation expense 95,148 192,467 Accrued rebates payable 63,917 57,163 Accrued royalties payable 20,331 30,797 Deferred revenue 7,889 13,037 Value added taxes payable 8,444 8,395 Forward foreign currency exchange contracts 7,675 10,448 Lease liabilities 10,401 10,700 Other 5,538 6,633 Total accounts payable and accrued liabilities $ 454,506 $ 570,621

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities	The following tables present the classification within the fair value hierarchy of financial assets and liabilities not disclosed elsewhere in these Condensed Consolidated Financial Statements that are remeasured on a recurring basis as of March 31, 2020 and December 31, 2019. There were no financial assets or liabilities that were remeasured using a quoted price in active markets for identical assets (Level 1) as of March 31, 2020. Fair Value Measurements at March 31, 2020 Significant Other Significant Total Assets: Other current assets: NQDC Plan assets $ 367 $ — $ 367 Other assets: NQDC Plan assets 14,917 — 14,917 Restricted investments (1) 4,554 — 4,554 Total other assets 19,471 — 19,471 Total assets $ 19,838 $ — $ 19,838 Liabilities: Current liabilities: NQDC Plan liability $ 367 $ — $ 367 Other long-term liabilities: NQDC Plan liability 14,917 — 14,917 Contingent consideration — 50,524 50,524 Total other long-term liabilities 14,917 50,524 65,441 Total liabilities $ 15,284 $ 50,524 $ 65,808 Fair Value Measurements at December 31, 2019 Significant Other Significant Total Assets: Other current assets: NQDC Plan assets $ 1,177 $ — $ 1,177 Other assets: NQDC Plan assets 16,288 — 16,288 Restricted investments (1) 3,168 — 3,168 Total other assets 19,456 — 19,456 Total assets $ 20,633 $ — $ 20,633 Liabilities: Current liabilities: NQDC Plan liability $ 1,177 $ — $ 1,177 Other long-term liabilities: NQDC Plan liability 16,288 — 16,288 Contingent consideration — 50,793 50,793 Total other long-term liabilities 16,288 50,793 67,081 Total liabilities $ 17,465 $ 50,793 $ 68,258 (1) The restricted investments at March 31, 2020 and December 31, 2019 secure the Company's irrevocable standby letters of credit obtained in connection with certain commercial agreements.
Liabilities Measured at Fair Value on Recurring Basis Using Level 3 Inputs	The following table represents a roll forward of contingent consideration. Contingent consideration at December 31, 2019 $ 50,793 Changes in fair value of contingent consideration (4) Foreign exchange remeasurement of Euro denominated contingent acquisition consideration (265) Contingent consideration at March 31, 2020 $ 50,524

DERIVATIVE INSTRUMENTS AND HE_2

DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES (Tables)	3 Months Ended
	Mar. 31, 2020
Derivative [Line Items]
Fair Value Carrying Amount of Derivatives	The fair value carrying amounts of the Company’s derivatives, as classified within the fair value hierarchy, were as follows: Balance Sheet Location March 31, 2020 December 31, 2019 Derivatives designated as hedging instruments: Asset Derivatives - Level 2 (1) Other current assets $ 30,077 $ 19,584 Other assets 16,984 13,539 Subtotal $ 47,061 $ 33,123 Liability Derivatives - Level 2 (1) Accounts payable and accrued liabilities $ 7,522 $ 8,184 Other long-term liabilities 5,790 5,493 Subtotal $ 13,312 $ 13,677 Derivatives not designated as hedging instruments: Asset Derivatives - Level 2 (1) Other current assets $ 200 $ 469 Liability Derivatives - Level 2 (1) Accounts payable and accrued liabilities $ 153 $ 2,264 Total Derivatives Assets $ 47,261 $ 33,592 Total Derivatives Liabilities $ 13,465 $ 15,941 (1) For additional discussion of fair value measurements, see Note 3 – Summary of Significant Accounting Policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019.
Summary of Impact of Gains and Losses from Derivatives Designated as Hedging Instruments	The following tables summarize the impact of gains and losses from the Company's derivatives on its Condensed Consolidated Statements of Comprehensive Income (Loss) for the periods presented. Three Months Ended Derivatives Designated as Cash Flow Hedging Instruments March 31, 2020 March 31, 2019 Amount of Gain (Loss) Recognized in Other Comprehensive Income $ 19,630 $ 12,825 Three Months Ended March 31, 2020 March 31, 2019 Derivatives Designated as Cash Flow Hedging Instruments Cash Flow Hedging Gains (Losses) Cash Flow Hedging Gains (Losses) Net product revenues as reported $ 489,043 $ 6,329 $ 394,483 $ 695 Operating expenses as reported $ 397,108 $ (1,673) $ 454,696 $ 271 Derivatives Not Designated as Hedging Instruments Gains (Losses) Recognized in Earnings Gains (Losses) Recognized in Earnings Operating Expenses $ 3,809 $ (2,978)
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Summary of Derivatives Designated as Hedging Instruments Outstanding	The following table summarizes the Company’s derivatives designated as hedging instruments outstanding as of March 31, 2020 (notional amounts in millions): Foreign Exchange Contracts Number of Aggregate Notional Maturity Purchase: Euros 137 165.4 Apr 2020 - Mar 2023 Sell: Australian Dollars 36 12.8 Apr 2020 - Mar 2021 Canadian Dollars 50 41.2 Apr 2020 - Mar 2021 Colombian Pesos 27 93,150.0 Apr 2020 - Mar 2021 Euros 374 605.3 Apr 2020 - Mar 2023 Norwegian Krone 36 82.0 Apr 2020 - Mar 2021 Total 660
Not Designated as Hedging Instrument
Derivative [Line Items]
Summary of Derivatives Designated as Hedging Instruments Outstanding	The following table summarizes the Company’s derivatives not designated as hedging instruments outstanding as of March 31, 2020 (notional amounts in millions): Foreign Exchange Contracts Number of Aggregate Notional Maturity Purchase: Euros 1 4.1 Jun 2020 Great British Pounds 1 8.3 Jun 2020 Sell: Colombian Pesos 1 49,800.0 Jun 2020 Rubles 1 1,055.0 Jun 2020 Total 4

LEASES (Tables)

LEASES (Tables)	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Schedule of ROU Assets and Lease Liabilities	The following table presents the Company’s right-of-use (ROU) assets and lease liabilities as of March 31, 2020: Lease Classification Classification March 31, December 31, Assets: Operating Other Assets $ 49,116 $ 49,045 Financing Other Assets 9,703 10,389 Total ROU assets $ 58,819 $ 59,434 Liabilities: Current: Operating Accounts payable and accrued liabilities $ 7,114 $ 7,451 Financing Accounts payable and accrued liabilities 3,287 3,249 Noncurrent: Operating Other long-term liabilities 44,529 44,092 Financing Other long-term liabilities 5,844 6,708 Total lease liabilities $ 60,774 $ 61,500
Schedule of Maturities of Operating Lease Liabilities	Maturities of lease liabilities as of March 31, 2020 by fiscal year were as follows: Maturity of Lease Liabilities Operating Financing Total Remainder of 2020 $ 8,814 $ 2,763 $ 11,577 2021 9,441 3,070 12,511 2022 8,749 2,339 11,088 2023 7,805 1,749 9,554 2024 5,995 — 5,995 Thereafter 22,044 — 22,044 Total lease payments 62,848 9,921 72,769 Less: Interest (11,205) (790) (11,995) Present value of lease liabilities $ 51,643 $ 9,131 $ 60,774
Schedule of Maturities of Finance Lease Liabilities	Maturities of lease liabilities as of March 31, 2020 by fiscal year were as follows: Maturity of Lease Liabilities Operating Financing Total Remainder of 2020 $ 8,814 $ 2,763 $ 11,577 2021 9,441 3,070 12,511 2022 8,749 2,339 11,088 2023 7,805 1,749 9,554 2024 5,995 — 5,995 Thereafter 22,044 — 22,044 Total lease payments 62,848 9,921 72,769 Less: Interest (11,205) (790) (11,995) Present value of lease liabilities $ 51,643 $ 9,131 $ 60,774
Schedule of Lease Cost	Three Months Ended Lease Cost Classification 2020 2019 Operating (1) Operating Expenses $ 2,748 $ 3,080 Financing: Amortization Operating Expenses 707 607 Interest expense Operating Expenses 125 161 Total lease costs $ 3,580 $ 3,848 (1) Includes short-term leases and variable lease costs, both of which were not material in the periods presented. Three Months Ended Supplemental Cash Flow Information 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Cash used in operating activities: Operating leases $ 1,440 $ 1,600 Financing leases $ 127 $ 161 Cash used in financing activities: Financing leases $ 823 $ 674 ROU assets obtained in exchange for lease obligations: Operating leases $ 2,427 $ 19 Financing leases $ 27 $ 68
Schedule of Other Information	Three Months Ended Other Information 2020 2019 Weighted average remaining lease term (in years): Operating leases 7.6 7.8 Financing leases 3.1 4.0 Weighted average discount rate: Operating leases 5.1 % 5.2 % Financing leases 5.3 % 5.4 %

DEBT (Tables)

DEBT (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Summary of Convertible Debt	The following table summarizes information regarding the Company’s convertible debt: March 31, December 31, 1.50% senior subordinated convertible notes due in October 2020 (the 2020 Notes) $ 374,993 $ 374,993 Unamortized discount (8,322) (12,078) Unamortized deferred offering costs (707) (1,033) Convertible Notes due in 2020, net (1) 365,964 361,882 0.599% senior subordinated convertible notes due in August 2024 (the 2024 Notes) 495,000 495,000 Unamortized discount (6,179) (6,533) Unamortized deferred offering costs (2,108) (2,229) Convertible Notes due in 2024, net 486,713 486,238 Total convertible debt, net $ 852,677 $ 848,120 Fair value of fixed rate convertible debt (2) : Convertible Notes due in October 2020 401,081 405,679 Convertible Notes due in August 2024 513,147 521,839 Total fair value of fixed rate convertible debt $ 914,228 $ 927,518 (1) The 2020 Notes are classified as a current liability in the periods presented since they mature in October 2020. (2) The fair value of the Company’s fixed-rate convertible debt is based on open market trades and is classified as Level 1 in the fair value hierarchy. For additional discussion of fair value measurements, see Note 3 – Summary of Significant Accounting Policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019.
Summary of Interest Expense on Debt	Interest expense on the Company’s convertible debt consisted of the following: Three Months Ended 2020 2019 Coupon interest expense $ 2,172 $ 2,157 Amortization of debt issuance costs 508 507 Accretion of discount on convertible notes 4,110 3,902 Total interest expense on convertible debt $ 6,790 $ 6,566

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Summary of Amounts Reclassified out of Accumulated Other Comprehensive Income	The following table summarizes amounts reclassified out of AOCI and their effect on the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for the three months ended March 31, 2020 and 2019. Condensed Consolidated Three Months Ended 2020 2019 Gains (losses) on cash flow hedges: Forward contracts Net product revenues $ 6,329 $ 695 Forward contracts Operating expenses (1,673) 271 Total gain (loss) on cash flow hedges $ 4,656 $ 966
Summary of Changes in Accumulated Balances of AOCI Including Current Period Other Comprehensive Income (Loss) and Reclassifications Out of AOCI	The following tables summarize changes in the accumulated balances for each component of AOCI, including current period other comprehensive income (loss) and reclassifications out of AOCI for the three months ended March 31, 2020 and 2019. Three Months Ended March 31, 2020 Unrealized Gains Unrealized Gains Other Total AOCI balance at December 31, 2019 $ 16,614 $ 3,565 $ (15) $ 20,164 Other comprehensive income (loss) before reclassifications 19,630 (1,334) 15 18,311 Less: net gain (loss) reclassified from AOCI 4,656 — 4,656 Tax effect — 308 — 308 Net current-period other comprehensive income (loss) 14,974 (1,026) 15 13,963 AOCI balance at March 31, 2020 $ 31,588 $ 2,539 $ — $ 34,127 Three Months Ended March 31, 2019 Unrealized Gains Unrealized Gains Other Total AOCI balance at December 31, 2018 $ 7,201 $ (1,917) $ (13) $ 5,271 Other comprehensive income (loss) before 12,825 3,455 (1) 16,279 Less: gain (loss) reclassified from AOCI 966 — — 966 Tax effect — (790) — (790) Net current-period other comprehensive income (loss) 11,859 2,665 (1) 14,523 AOCI balance at March 31, 2019 $ 19,060 $ 748 $ (14) $ 19,794

REVENUE, CREDIT CONCENTRATION_2

REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2020
Concentration Risk And Geographic Information [Abstract]
Schedule of Total Revenues from External Customers and Collaborative Partners by Geographic Region	The following table disaggregates Total Revenues from external customers and collaborative partners by geographic region. Net product revenues by geographic region are based on patient location for the Company’s commercial products, except for Aldurazyme, which is sold exclusively to Genzyme Corporation, a wholly owned subsidiary of Sanofi (Genzyme) who markets and sells Aldurazyme world-wide. Aldurazyme revenues earned by the Company are included in the U.S. region as the transactions are with Genzyme whose headquarters is located in the U.S. Three Months Ended 2020 2019 Total revenues by geographic region: United States $ 244,172 $ 190,936 Europe 145,036 124,539 Latin America 59,924 33,839 Rest of world 52,937 51,431 Total revenues $ 502,069 $ 400,745
Schedule of Net Product Revenues by Product	The following table disaggregates Net Product Revenues by product. Three Months Ended 2020 2019 Net product revenues by product: Brineura $ 23,970 $ 12,180 Firdapse 1,288 5,112 Kuvan 122,028 106,924 Naglazyme 114,256 86,927 Palynziq 34,632 12,272 Vimizim 137,203 125,801 Total net product revenues marketed by the Company $ 433,377 $ 349,216 Aldurazyme net product revenues marketed by Genzyme 55,666 45,267 Total net product revenues $ 489,043 $ 394,483
Schedule of Total Net Product Revenues Based on Patient Location	The table below disaggregates total Net Product Revenues based on patient location for products sold directly by the Company, and global sales of Aldurazyme, which is marketed by Genzyme. Three Months Ended 2020 2019 United States $ 181,671 $ 144,285 Europe 140,851 123,085 Latin America 59,924 33,840 Rest of world 50,931 48,006 Total net product revenues marketed by the Company 433,377 349,216 Aldurazyme net product revenues marketed by Genzyme 55,666 45,267 Total net product revenues $ 489,043 $ 394,483
Schedule of Net Product Revenue Concentrations Attributed to Largest Customers	The following table illustrates the percentage of the Company’s total Net Product Revenues attributed to the Company’s largest customers for the periods presented. Three Months Ended 2020 2019 Customer A 13 % 18 % Customer B 12 % 11 % Customer C 11 % 12 % Customer D 11 % 11 % Total 47 % 52 %

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	3 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Schedule of Stock-Based Compensation Expense	Compensation expense included in the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for all stock-based compensation arrangements was as follows: Three Months Ended March 31, 2020 2019 Cost of sales $ 5,084 $ 4,819 Research and development 13,711 13,833 Selling, general and administrative 28,199 24,109 Total stock-based compensation expense $ 46,994 $ 42,761

NET INCOME (LOSS) PER COMMON _2

NET INCOME (LOSS) PER COMMON SHARE (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per common share (in thousands of common shares): Three Months Ended March 31, 2020 2019 Numerator: Net Income (Loss), basic $ 81,381 $ (56,473) Add: Interest on 2024 notes 936 — Net Income (Loss), diluted $ 82,317 $ (56,473) Denominator: Weighted-average common shares outstanding, basic 179,898 178,271 Effect of dilutive securities: Options to purchase common stock 1,708 — Common stock issuable under the 2024 notes 3,970 — Unvested RSUs 1,037 — Common stock potentially issuable for ESPP purchases 346 — Common shares held by the NQDC 204 — Weighted-average common shares outstanding, diluted 187,163 178,271 Net Income (Loss) per common share, basic $ 0.45 $ (0.32) Net Income (Loss) per common share, diluted $ 0.44 $ (0.32)
Schedule Of Anti-Dilutive Common Stock Excluded From Computation of Diluted Net Loss Per Share	In addition to the equity instruments included in the table above, the table below presents potential shares of common stock that were excluded from the computation of diluted earnings per common share as they were anti-dilutive (in thousands): Three Months Ended March 31, 2020 2019 Options to purchase common stock 6,063 7,749 Common stock issuable under the 2020 Notes 3,983 3,983 Common stock issuable under the 2024 Notes — 3,970 Unvested RSUs 3,811 4,164 Common stock potentially issuable for ESPP purchases 232 417 Common stock held by the NQDC — 202 Total number of potentially issuable shares 14,089 20,485

Financial Instruments - Schedul

Financial Instruments - Schedule of Cash, Cash Equivalents and Available-for-Sale Securities by Significant Investment Category (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019		Mar. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,145,892	$ 1,161,152
Gross Unrealized Gains	5,222	4,713
Gross Unrealized Losses	(1,922)	(80)
Aggregate Fair Value	1,149,192	1,165,785
Cash and Cash Equivalents	476,632	437,446	[1]	$ 364,369	$ 493,982
Short-term Marketable Securities	381,764	316,361	[1]
Long-term Marketable Securities	290,796	411,978	[1]
Level 1: | Cash
Schedule of Available-for-sale Securities [Line Items]
Cash	287,756	259,347
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Aggregate Fair Value	287,756	259,347
Cash and Cash Equivalents	287,756	259,347
Short-term Marketable Securities	0	0
Long-term Marketable Securities	0	0
Level 2:
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	858,136	901,805
Gross Unrealized Gains	5,222	4,713
Gross Unrealized Losses	(1,922)	(80)
Aggregate Fair Value	861,436	906,438
Cash and Cash Equivalents	188,876	178,099
Short-term Marketable Securities	381,764	316,361
Long-term Marketable Securities	290,796	411,978
Level 2: | Money market instruments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	188,876	173,100
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Aggregate Fair Value	188,876	173,100
Cash and Cash Equivalents	188,876	173,100
Short-term Marketable Securities	0	0
Long-term Marketable Securities	0	0
Level 2: | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	475,439	518,523
Gross Unrealized Gains	1,450	3,575
Gross Unrealized Losses	(1,888)	(12)
Aggregate Fair Value	475,001	522,086
Cash and Cash Equivalents	0	0
Short-term Marketable Securities	286,894	233,294
Long-term Marketable Securities	188,107	288,792
Level 2: | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	181,818	209,633
Gross Unrealized Gains	3,561	993
Gross Unrealized Losses		(67)
Aggregate Fair Value	185,379	210,559
Cash and Cash Equivalents	0	4,999
Short-term Marketable Securities	92,597	83,067
Long-term Marketable Securities	92,782	122,493
Level 2: | Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,454
Gross Unrealized Gains	59
Gross Unrealized Losses	(33)
Aggregate Fair Value	11,480
Cash and Cash Equivalents	0
Short-term Marketable Securities	2,273
Long-term Marketable Securities	9,207
Level 2: | Foreign and other
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	549	549
Gross Unrealized Gains	152	145
Gross Unrealized Losses	(1)	(1)
Aggregate Fair Value	700	693
Cash and Cash Equivalents	0	0
Short-term Marketable Securities		0
Long-term Marketable Securities	$ 700	$ 693
Minimum
Schedule of Available-for-sale Securities [Line Items]
Long term marketable securities maturity period	1 year	1 year
Maximum
Schedule of Available-for-sale Securities [Line Items]
Short term marketable securities maturity period	1 year	1 year
Long term marketable securities maturity period	5 years	5 years
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - Fair Value, Measurements, Recurring $ in Millions	Mar. 31, 2020USD ($)investment	Dec. 31, 2019USD ($)
Schedule of Available-for-sale Securities [Line Items]
Number of investments | investment	3
Strategic Investment
Schedule of Available-for-sale Securities [Line Items]
Strategic investments fair value | $	$ 6.2	$ 6.2

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Intangible assets:
Finite-lived intangible assets	$ 623,972	$ 652,734
Accumulated amortization	180,255	196,154
Net carrying value	$ 443,717	$ 456,580	[1]
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jan. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Gain (loss) on disposition of other assets	$ 59,495	$ 0
Finite-lived intangible assets	623,972			$ 652,734
Accumulated amortization	180,255			$ 196,154
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Firdapse
Goodwill [Line Items]
Cash payment			$ 67,200
Gain (loss) on disposition of other assets	59,500
Increase (decrease) in goodwill	(800)
Finite-lived intangible assets	32,200
Accumulated amortization	$ 31,600

Property Plant and Equipment -

Property Plant and Equipment - Schedule of Property Plant and Equipment Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,579,981	$ 1,559,968
Accumulated depreciation	(570,009)	(549,100)
Total property, plant and equipment, net	1,009,972	1,010,868	[1]
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	727,272	725,906
Manufacturing and laboratory equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	376,035	366,951
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	170,132	167,554
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	51,323	51,324
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	38,124	38,569
Land improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,349	7,349
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	90,418	90,418
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 119,328	$ 111,897
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.

Property Plant and Equipment _2

Property Plant and Equipment - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 21.5	$ 21.4
Depreciation capitalized into inventory	$ 11.2	$ 6.5

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Inventory [Line Items]
Raw materials	$ 82,207	$ 74,442
Work-in-process	371,963	349,978
Finished goods	251,482	255,855
Total inventory	705,652	$ 680,275	[1]
Pre-Launch Valoctocogene Roxaparvovec
Inventory [Line Items]
Total inventory	$ 52,500
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts payable and accrued operating expenses	$ 235,163	$ 240,981
Accrued compensation expense	95,148	192,467
Accrued rebates payable	63,917	57,163
Accrued royalties payable	20,331	30,797
Deferred revenue	7,889	13,037
Value added taxes payable	8,444	8,395
Forward foreign currency exchange contracts	7,675	10,448
Lease liabilities	10,401	10,700
Other	5,538	6,633
Total accounts payable and accrued liabilities	$ 454,506	$ 570,621	[1]
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Financial Assets and Liabilities (Detail) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Quoted Price in Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets remeasured	$ 0
Liabilities remeasured	0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	19,471,000	$ 19,456,000
Fair value of financial assets, Total	19,838,000	20,633,000
Fair value of other non-current liabilities	65,441,000	67,081,000
Fair value of financial liabilities, Total	65,808,000	68,258,000
Fair Value, Measurements, Recurring | NQDC Plan liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	367,000	1,177,000
Fair value of other non-current liabilities	14,917,000	16,288,000
Fair Value, Measurements, Recurring | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current liabilities	50,524,000	50,793,000
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	19,471,000	19,456,000
Fair value of financial assets, Total	19,838,000	20,633,000
Fair value of other non-current liabilities	14,917,000	16,288,000
Fair value of financial liabilities, Total	15,284,000	17,465,000
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | NQDC Plan liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	367,000	1,177,000
Fair value of other non-current liabilities	14,917,000	16,288,000
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	0	0
Fair value of financial assets, Total	0	0
Fair value of other non-current liabilities	50,524,000	50,793,000
Fair value of financial liabilities, Total	50,524,000	50,793,000
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | NQDC Plan liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	0	0
Fair value of other non-current liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current liabilities	50,524,000	50,793,000
Fair Value, Measurements, Recurring | NQDC Plan assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	367,000	1,177,000
Fair value of other non-current assets	14,917,000	16,288,000
Fair Value, Measurements, Recurring | NQDC Plan assets | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	367,000	1,177,000
Fair value of other non-current assets	14,917,000	16,288,000
Fair Value, Measurements, Recurring | NQDC Plan assets | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	0	0
Fair value of other non-current assets	0	0
Fair Value, Measurements, Recurring | Restricted Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	4,554,000	3,168,000
Fair Value, Measurements, Recurring | Restricted Investments | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	4,554,000	3,168,000
Fair Value, Measurements, Recurring | Restricted Investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	$ 0	$ 0

Fair Value Measurements - Liabi

Fair Value Measurements - Liabilities Measured at Fair Value on Recurring Basis Using Level 3 Inputs (Detail) - Contingent Payment $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration at December 31, 2019	$ 50,793
Changes in fair value of contingent consideration	(4)
Foreign exchange remeasurement of Euro denominated contingent acquisition consideration	(265)
Contingent consideration at March 31, 2020	$ 50,524

Derivative Instruments and He_3

Derivative Instruments and Hedging Strategies - Summary of Derivatives Designated as Hedging Instruments Outstanding (Detail) - Derivatives Designated As Hedging Instruments - Foreign exchange contracts € in Millions, kr in Millions, $ in Millions, $ in Millions, $ in Millions	Mar. 31, 2020CAD ($)Derivative	Mar. 31, 2020AUD ($)Derivative	Mar. 31, 2020EUR (€)Derivative	Mar. 31, 2020NOK (kr)Derivative	Mar. 31, 2020COP ($)Derivative
Derivative [Line Items]
Number of Contracts	660	660	660	660	660
Australian Dollars | Sell
Derivative [Line Items]
Number of Contracts	36	36	36	36	36
Aggregate Notional Amount in Foreign Currency | $		$ 12.8
Canadian Dollars | Sell
Derivative [Line Items]
Number of Contracts	50	50	50	50	50
Aggregate Notional Amount in Foreign Currency | $	$ 41.2
Colombian Pesos | Sell
Derivative [Line Items]
Number of Contracts	27	27	27	27	27
Aggregate Notional Amount in Foreign Currency | $					$ 93,150
Euros | Sell
Derivative [Line Items]
Number of Contracts	374	374	374	374	374
Aggregate Notional Amount in Foreign Currency | €			€ 605.3
Euros | Purchase
Derivative [Line Items]
Number of Contracts	137	137	137	137	137
Aggregate Notional Amount in Foreign Currency | €			€ 165.4
Norwegian Krone | Sell
Derivative [Line Items]
Number of Contracts	36	36	36	36	36
Aggregate Notional Amount in Foreign Currency | kr				kr 82

Derivative Instruments and He_4

Derivative Instruments and Hedging Strategies - Summary of Derivatives Not Designated as Hedging Instruments Outstanding (Detail) - Not Designated as Hedging Instrument ₽ in Millions, € in Millions, £ in Millions, $ in Millions	Mar. 31, 2020RUB (₽)Derivative	Mar. 31, 2020EUR (€)Derivative	Mar. 31, 2020COP ($)Derivative	Mar. 31, 2020GBP (£)Derivative
Derivative [Line Items]
Number of Contracts	4	4	4	4
Euros | Foreign exchange contracts | Purchase
Derivative [Line Items]
Number of Contracts	1	1	1	1
Aggregate Notional Amount in Foreign Currency | €		€ 4.1
Great British Pounds | Foreign exchange contracts | Purchase
Derivative [Line Items]
Number of Contracts	1	1	1	1
Aggregate Notional Amount in Foreign Currency | £				£ 8.3
Colombian Pesos | Foreign exchange contracts | Sell
Derivative [Line Items]
Number of Contracts	1	1	1	1
Aggregate Notional Amount in Foreign Currency | $			$ 49,800
Rubles | Foreign exchange contracts | Sell
Derivative [Line Items]
Number of Contracts	1	1	1	1
Aggregate Notional Amount in Foreign Currency | ₽	₽ 1,055

Derivative Instruments and He_5

Derivative Instruments and Hedging Strategies - Fair Value Carrying Amount of Derivatives (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative Asset, Fair Value	$ 47,261	$ 33,592
Derivative Liability, Fair Value	13,465	15,941
Level 2: | Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Derivative Asset, Fair Value	47,061	33,123
Derivative Liability, Fair Value	13,312	13,677
Level 2: | Derivatives Designated As Hedging Instruments | Other current assets
Derivative [Line Items]
Derivative Asset, Fair Value	30,077	19,584
Level 2: | Derivatives Designated As Hedging Instruments | Other assets
Derivative [Line Items]
Derivative Asset, Fair Value	16,984	13,539
Level 2: | Derivatives Designated As Hedging Instruments | Accounts payable and accrued liabilities
Derivative [Line Items]
Derivative Liability, Fair Value	7,522	8,184
Level 2: | Derivatives Designated As Hedging Instruments | Other long-term liabilities
Derivative [Line Items]
Derivative Liability, Fair Value	5,790	5,493
Level 2: | Not Designated as Hedging Instrument | Other current assets
Derivative [Line Items]
Derivative Asset, Fair Value	200	469
Level 2: | Not Designated as Hedging Instrument | Accounts payable and accrued liabilities
Derivative [Line Items]
Derivative Liability, Fair Value	$ 153	$ 2,264

Derivative Instruments and He_6

Derivative Instruments and Hedging Strategies - Summary of Impact of Gains and Losses from Derivatives Designated as Hedging Instruments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Net product revenues	$ 502,069	$ 400,745
Operating expenses as reported	397,108	454,696
Derivatives Designated As Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income	19,630	12,825
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Recognized in Earnings	3,809	(2,978)
Operating Expense | Derivatives Designated As Hedging Instruments | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Hedging Gains (Losses) Reclassified into Earnings	(1,673)	271
Net product revenues
Derivative Instruments, Gain (Loss) [Line Items]
Net product revenues	489,043	394,483
Net product revenues | Derivatives Designated As Hedging Instruments | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Hedging Gains (Losses) Reclassified into Earnings	$ 6,329	$ 695

Derivative Instruments and He_7

Derivative Instruments and Hedging Strategies - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Amount reclassified from AOCI to earnings as related to forecasted revenue and operating expense transactions	$ 21

Leases - Schedule of ROU Assets

Leases - Schedule of ROU Assets and Lease Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets:
Operating	$ 49,116	$ 49,045
Financing	9,703	10,389
Total ROU assets	58,819	59,434
Liabilities:
Operating, Current	7,114	7,451
Financing, Current	3,287	3,249
Operating, Noncurrent	44,529	44,092
Financing, Noncurrent	5,844	6,708
Total lease liabilities	$ 60,774	$ 61,500

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Lease Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Operating
Remainder of 2020	$ 8,814
2021	9,441
2022	8,749
2023	7,805
2024	5,995
Thereafter	22,044
Total lease payments	62,848
Less: Interest	(11,205)
Present value of lease liabilities	51,643
Financing
Remainder of 2020	2,763
2021	3,070
2022	2,339
2023	1,749
2024	0
Thereafter	0
Total lease payments	9,921
Less: Interest	(790)
Present value of lease liabilities	9,131
Total
Remainder of 2020	11,577
2021	12,511
2022	11,088
2023	9,554
2024	5,995
Thereafter	22,044
Total lease payments	72,769
Less: Interest	(11,995)
Present value of lease liabilities	$ 60,774	$ 61,500

Leases - Schedule of Lease Cost

Leases - Schedule of Lease Cost (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lease Cost
Total lease costs	$ 3,580	$ 3,848
Operating Expenses
Lease Cost
Operating	2,748	3,080
Amortization	707	607
Interest expense	$ 125	$ 161

Leases - Schedule of Other Info

Leases - Schedule of Other Information (Detail) - USD ($)	Mar. 31, 2020	Mar. 31, 2019
Weighted average remaining lease term (in years):
Operating leases	7 years 7 months 6 days	7 years 9 months 18 days
Financing leases	3 years 1 month 6 days	4 years
Weighted average discount rate:
Operating leases	5.10%	5.20%
Financing leases	5.30%	5.40%
Additional leases not yet commenced (undiscounted):
Operating lease liability to commence in the remainder of 2019	$ 0

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash used in operating activities:
Operating leases	$ 1,440	$ 1,600
Financing leases	127	161
Cash used in financing activities:
Financing leases	823	674
ROU assets obtained in exchange for lease obligations:
Operating leases	2,427	19
Financing leases	$ 27	$ 68

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	1 Months Ended
	Oct. 31, 2018	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Carrying value of equity component		$ 870,000,000
The 2018 Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 200,000,000
To repay early, minimum required amount outstanding with certain other conditions have not been met	100,000,000
Debt issuance costs	$ 1,000,000
Outstanding amount		$ 0	$ 0
The 2018 Credit Facility | Minimum
Debt Instrument [Line Items]
Percentage of commitment fees payable on undrawn amount	0.15%
The 2018 Credit Facility | Minimum | LIBOR Rate
Debt Instrument [Line Items]
Debt instrument interest rate percentage	1.00%
The 2018 Credit Facility | Minimum | Base Rate
Debt Instrument [Line Items]
Debt instrument interest rate percentage	0.00%
The 2018 Credit Facility | Maximum
Debt Instrument [Line Items]
Percentage of commitment fees payable on undrawn amount	0.35%
The 2018 Credit Facility | Maximum | LIBOR Rate
Debt Instrument [Line Items]
Debt instrument interest rate percentage	1.95%
The 2018 Credit Facility | Maximum | Base Rate
Debt Instrument [Line Items]
Debt instrument interest rate percentage	0.95%

Debt - Summary of Convertible D

Debt - Summary of Convertible Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Convertible Notes	$ 870,000
Short-term convertible debt, net	365,964	$ 361,882	[1]
Convertible Notes, net of unamortized discount and deferred offering costs	486,713	486,238	[1]
Total convertible debt, net	852,677	848,120
Total fair value of fixed rate convertible debt	$ 914,228	$ 927,518
1.50% Senior Subordinated Convertible Notes Due in October 2020
Debt Instrument [Line Items]
Convertible notes stated rate	1.50%	1.50%
Convertible Notes	$ 374,993	$ 374,993
Convertible debt, unamortized discount	(8,322)	(12,078)
Convertible debt, Unamortized deferred offering costs	(707)	(1,033)
Short-term convertible debt, net	365,964	361,882
Total fair value of fixed rate convertible debt	$ 401,081	$ 405,679
0.599% Senior Subordinated Convertible Notes Due in August 2024
Debt Instrument [Line Items]
Convertible notes stated rate	0.599%	0.599%
Convertible Notes	$ 495,000	$ 495,000
Convertible debt, unamortized discount	(6,179)	(6,533)
Convertible debt, Unamortized deferred offering costs	(2,108)	(2,229)
Convertible Notes, net of unamortized discount and deferred offering costs	486,713	486,238
Total fair value of fixed rate convertible debt	$ 513,147	$ 521,839
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.

Debt - Summary of Interest Expe

Debt - Summary of Interest Expense on Convertible Debt (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule Of Interest Expenses [Line Items]
Total interest expense on convertible debt	$ 6,915	$ 6,727
Convertible Senior Notes
Schedule Of Interest Expenses [Line Items]
Coupon interest expense	2,172	2,157
Amortization of debt issuance costs	508	507
Accretion of discount on convertible notes	4,110	3,902
Total interest expense on convertible debt	$ 6,790	$ 6,566

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income - Amounts Reclassified out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net product revenues	$ 502,069	$ 400,745
Total gain (loss) on cash flow hedges	104,961	(53,951)
Net product revenues
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net product revenues	489,043	394,483
Amount Reclassified from AOCI Gain (Loss) | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total gain (loss) on cash flow hedges	4,656	966
Amount Reclassified from AOCI Gain (Loss) | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Forward contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operating expenses	(1,673)	271
Amount Reclassified from AOCI Gain (Loss) | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Net product revenues | Forward contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net product revenues	$ 6,329	$ 695

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income - Summary of Changes in Accumulated Balances of AOCI Including Current Period Other Comprehensive Income (Loss) and Reclassifications Out of AOCI (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	[2]	$ 3,122,381	[1]	$ 2,967,940
Other comprehensive income (loss) before      reclassifications		18,311		16,279
Less: net gain (loss) reclassified from AOCI		4,656		966
Tax effect		308		(790)
Net current-period other comprehensive income (loss)		13,963		14,523
Ending Balance		3,239,962		2,936,627
Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		16,614		7,201
Other comprehensive income (loss) before      reclassifications		19,630		12,825
Less: net gain (loss) reclassified from AOCI		4,656		966
Tax effect		0		0
Net current-period other comprehensive income (loss)		14,974		11,859
Ending Balance		31,588		19,060
Unrealized Gains (Losses) on Available for-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		3,565		(1,917)
Other comprehensive income (loss) before      reclassifications		(1,334)		3,455
Less: net gain (loss) reclassified from AOCI				0
Tax effect		308		(790)
Net current-period other comprehensive income (loss)		(1,026)		2,665
Ending Balance		2,539		748
Other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		(15)		(13)
Other comprehensive income (loss) before      reclassifications		15		(1)
Less: net gain (loss) reclassified from AOCI		0		0
Tax effect		0		0
Net current-period other comprehensive income (loss)		15		(1)
Ending Balance		0		(14)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	[2]	20,164		5,271
Ending Balance		$ 34,127		$ 19,794
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.
[2]	The beginning balances were derived from the audited Consolidated Financial Statements included in Company’s Annual Report on Form 10-K for the years ended December 31, 2019 and 2018, respectively, filed with the SEC on February 27, 2020.

Revenue, Credit Concentration_3

Revenue, Credit Concentrations and Geographic Information - Additional Information (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020USD ($)Segment	Dec. 31, 2019USD ($)
Concentration Risk And Geographic Information [Line Items]
Number of operating business segment | Segment	1
Accounts receivable, net	$ 396,384	$ 377,404	[1]
Customers
Concentration Risk And Geographic Information [Line Items]
Accounts receivable, net	$ 86,500	$ 60,200
Credit Concentration Risk | Accounts Receivable | Customer One
Concentration Risk And Geographic Information [Line Items]
Concentration risk, percentage	29.00%	24.00%
Credit Concentration Risk | Accounts Receivable | Customer Two
Concentration Risk And Geographic Information [Line Items]
Concentration risk, percentage	14.00%	16.00%
[1]	December 31, 2019 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on February 27, 2020.

Revenue, Credit Concentration_4

Revenue, Credit Concentrations and Geographic Information - Disaggregates of Total Revenues from External Customers and Collaborative Partners by Geographic Region (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from External Customer [Line Items]
Total revenues	$ 502,069	$ 400,745
United States
Revenue from External Customer [Line Items]
Total revenues	244,172	190,936
Europe
Revenue from External Customer [Line Items]
Total revenues	145,036	124,539
Latin America
Revenue from External Customer [Line Items]
Total revenues	59,924	33,839
Rest of world
Revenue from External Customer [Line Items]
Total revenues	$ 52,937	$ 51,431

Revenue, Credit Concentration_5

Revenue, Credit Concentrations and Geographic Information - Disaggregates of Net Product Revenues by Product (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from External Customer [Line Items]
Net product revenues	$ 502,069	$ 400,745
Marketed by Company
Revenue from External Customer [Line Items]
Net product revenues	433,377	349,216
Aldurazyme | Marketed by Genzyme
Revenue from External Customer [Line Items]
Net product revenues	55,666	45,267
Brineura | Marketed by Company
Revenue from External Customer [Line Items]
Net product revenues	23,970	12,180
Firdapse | Marketed by Company
Revenue from External Customer [Line Items]
Net product revenues	1,288	5,112
Kuvan | Marketed by Company
Revenue from External Customer [Line Items]
Net product revenues	122,028	106,924
Naglazyme | Marketed by Company
Revenue from External Customer [Line Items]
Net product revenues	114,256	86,927
Palynziq | Marketed by Company
Revenue from External Customer [Line Items]
Net product revenues	34,632	12,272
Vimizim | Marketed by Company
Revenue from External Customer [Line Items]
Net product revenues	137,203	125,801
Total net product revenues
Revenue from External Customer [Line Items]
Net product revenues	$ 489,043	$ 394,483

Revenue, Credit Concentration_6

Revenue, Credit Concentrations and Geographic Information - Disaggregates of Total Net Product Revenues Based on Patient Location (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Net product revenues	$ 502,069	$ 400,745
United States
Disaggregation of Revenue [Line Items]
Net product revenues	244,172	190,936
Europe
Disaggregation of Revenue [Line Items]
Net product revenues	145,036	124,539
Latin America
Disaggregation of Revenue [Line Items]
Net product revenues	59,924	33,839
Rest of world
Disaggregation of Revenue [Line Items]
Net product revenues	52,937	51,431
Total net product revenues
Disaggregation of Revenue [Line Items]
Net product revenues	489,043	394,483
Marketed by Company
Disaggregation of Revenue [Line Items]
Net product revenues	433,377	349,216
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim
Disaggregation of Revenue [Line Items]
Net product revenues	433,377	349,216
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | United States
Disaggregation of Revenue [Line Items]
Net product revenues	181,671	144,285
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Europe
Disaggregation of Revenue [Line Items]
Net product revenues	140,851	123,085
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Latin America
Disaggregation of Revenue [Line Items]
Net product revenues	59,924	33,840
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Rest of world
Disaggregation of Revenue [Line Items]
Net product revenues	50,931	48,006
Marketed by Genzyme | Aldurazyme
Disaggregation of Revenue [Line Items]
Net product revenues	$ 55,666	$ 45,267

Revenue, Credit Concentration_7

Revenue, Credit Concentrations and Geographic Information - Total Net Product Revenue Concentrations Attributed to Largest Customers (Detail) - Customer Concentration Risk - Net Product Revenue	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Concentration Risk [Line Items]
Concentration risk, percentage	47.00%	52.00%
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	13.00%	18.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%	11.00%
Customer C
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%	12.00%
Customer D
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%	11.00%

Stock-Based Compensation - Expe

Stock-Based Compensation - Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 46,994	$ 42,761
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	5,084	4,819
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	13,711	13,833
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 28,199	$ 24,109

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense capitalized to inventory		$ 4.6	$ 3.8
Restricted Stock Unit Awards With Market Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted restricted stock units	126,710	126,710
Award vesting service period	3 years
Base percentage of annual target ceiling	100.00%
Weighted-average fair value per RSU granted (in dollars per share)	$ 112.12
Restricted Stock Unit Awards With Market Conditions | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual percentage of shares earned, performance metric	0.00%
Percentage of Annual TSR multiplier on absolute basis	50.00%
Restricted Stock Unit Awards With Market Conditions | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual percentage of shares earned, performance metric	200.00%
Restricted Stock Unit Awards With Performance Conditions, Non-GAAP Income Target
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted restricted stock units	63,400	63,400
Award vesting service period	3 years
Weighted-average fair value per RSU granted (in dollars per share)	$ 73.82
Restricted Stock Unit Awards With Performance Conditions, Non-GAAP Income Target | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual percentage of shares earned, performance metric	50.00%
Restricted Stock Unit Awards With Performance Conditions, Non-GAAP Income Target | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual percentage of shares earned, performance metric	200.00%
Restricted Stock Unit Awards With Performance Conditions, Strategic Goal Target
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted restricted stock units	63,400	63,400
Award vesting service period	3 years
Weighted-average fair value per RSU granted (in dollars per share)	$ 73.82
Restricted Stock Unit Awards With Performance Conditions, Strategic Goal Target | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual percentage of shares earned, performance metric	50.00%
Restricted Stock Unit Awards With Performance Conditions, Strategic Goal Target | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual percentage of shares earned, performance metric	200.00%

NET INCOME (LOSS) PER COMMON _3

NET INCOME (LOSS) PER COMMON SHARE - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net Income (Loss), basic	$ 81,381	$ (56,473)
Net Income (Loss), diluted	$ 82,317	$ (56,473)
Denominator:
Weighted average number of shares outstanding, basic	179,898	178,271
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Weighted-average common shares outstanding, diluted	187,163	178,271
Net Income (Loss) per common share, basic (in dollars per share)	$ 0.45	$ (0.32)
Net Income (Loss) per common share, diluted (in dollars per share)	$ 0.44	$ (0.32)
Common stock issuable under the 2024 Notes
Numerator:
Add: Interest on 2024 notes	$ 936	$ 0
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	3,970	0
Options to purchase common stock
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	1,708	0
Unvested restricted stock units
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	1,037	0
Common stock potentially issuable for ESPP purchases
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	346	0
Common stock held by the NQDC
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities	204	0

NET INCOME (LOSS) PER COMMON _4

NET INCOME (LOSS) PER COMMON SHARE - Schedule Of Anti-Dilutive Common Stock Excluded From Computation of Diluted Net Loss Per Share (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	14,089	20,485
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	6,063	7,749
Common stock issuable under the 2020 Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	3,983	3,983
Common stock issuable under the 2024 Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	0	3,970
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	3,811	4,164
Common stock potentially issuable for ESPP purchases
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	232	417
Common stock held by the NQDC
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	0	202

NET INCOME (LOSS) PER COMMON _5

NET INCOME (LOSS) PER COMMON SHARE - Additional Information (Detail) - $ / shares	Mar. 31, 2020	Mar. 31, 2019
Convertible Notes due 2020
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price, per share (in dollars per share)	$ 94.15	$ 94.15

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones	$ 355.4
Contingent liabilities	50.5
Clinical and Post Marketing Services
Commitments And Contingencies [Line Items]
Purchase commitments and other minimum contractual obligations	113.4
Third Party
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones	66
Completed Programs | Third Party
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones	$ 243.1

Uncategorized Items - bmrn-2020

Label	Element	Value
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (2,727,000)
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 0