BioMarin Pharmaceutical (BMRN) 10-Q 29 Oct 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 26, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
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		183,593,434
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001048477
Current Fiscal Year End Date	--12-31

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	[1]
Current assets:
Cash and cash equivalents	$ 617,143	$ 649,158
Short-term investments	462,333	416,228
Accounts receivable, net	374,937	448,351
Inventory	749,406	698,548
Other current assets	107,751	129,934
Total current assets	2,311,570	2,342,219
Noncurrent assets:
Long-term investments	466,618	285,473
Property, plant and equipment, net	1,024,787	1,032,471
Intangible assets, net	388,487	417,271
Goodwill	196,199	196,199
Deferred tax assets	1,445,109	1,432,150
Other assets	144,705	142,237
Total assets	5,977,475	5,848,020
Current liabilities:
Accounts payable and accrued liabilities	466,711	492,548
Short-term contingent consideration	48,187	0
Total current liabilities	514,898	492,548
Noncurrent liabilities:
Long-term convertible debt, net	1,078,093	1,075,145
Long-term contingent consideration	15,204	60,130
Other long-term liabilities	103,131	114,195
Total liabilities	1,711,326	1,742,018
Stockholders’ equity:
Common stock, $0.001 par value: 500,000,000 shares authorized; 183,567,424 and 181,740,999 shares issued and outstanding, respectively.	184	182
Additional paid-in capital	5,133,742	4,993,407
Company common stock held by Nonqualified Deferred Compensation Plan (the NQDC)	(10,225)	(9,839)
Accumulated other comprehensive income (loss)	10,239	(16,139)
Accumulated deficit	(867,791)	(861,609)
Total stockholders’ equity	4,266,149	4,106,002	[2]
Total liabilities and stockholders’ equity	$ 5,977,475	$ 5,848,020
[1]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.
[2]	The beginning balances for the nine-month periods were derived from the audited Consolidated Financial Statements included in Company’s Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on February 26, 2021.

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
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)	183,567,424	181,740,999
Common stock, shares outstanding (in shares)	183,567,424	181,740,999

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
REVENUES:
Total revenues	$ 408,742	$ 476,784	$ 1,396,465	$ 1,408,338
OPERATING EXPENSES:
Cost of sales	103,537	188,793	350,765	398,134
Research and development	157,869	147,053	467,701	471,449
Selling, general and administrative	183,333	179,450	541,812	542,157
Intangible asset amortization and contingent consideration	17,222	17,429	52,648	48,018
Gain on sale of nonfinancial assets	0	0	0	(59,495)
Total operating expenses	461,961	532,725	1,412,926	1,400,263
INCOME (LOSS) FROM OPERATIONS	(53,219)	(55,941)	(16,461)	8,075
Equity in the income (loss) of BioMarin/Genzyme LLC	177	(921)	(1,349)	(1,077)
Interest income	1,827	4,004	8,737	13,539
Interest expense	(3,870)	(9,597)	(11,491)	(24,560)
Other income, net	8,925	1,239	11,788	1,886
INCOME (LOSS) BEFORE INCOME TAXES	(46,160)	(61,216)	(8,776)	(2,137)
Benefit from income taxes	(9,666)	(846,019)	(2,594)	(839,138)
NET INCOME (LOSS)	$ (36,494)	$ 784,803	$ (6,182)	$ 837,001
NET INCOME (LOSS) PER SHARE, BASIC (in dollars per share)	$ (0.20)	$ 4.33	$ (0.03)	$ 4.63
NET INCOME (LOSS) PER SHARE, DILUTED (in dollars per share)	$ (0.20)	$ 4.01	$ (0.03)	$ 4.39
Weighted average common shares outstanding, basic (in shares)	183,214	181,142	182,616	180,592
Weighted average common shares outstanding, diluted (in shares)	183,214	197,674	182,616	194,959
COMPREHENSIVE INCOME (LOSS)	$ (25,316)	$ 765,138	$ 20,196	$ 827,222
Net product revenues
REVENUES:
Total revenues	393,840	460,741	1,348,279	1,368,816
Royalty and other revenues
REVENUES:
Total revenues	$ 14,902	$ 16,043	$ 48,186	$ 39,522

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands		Total		Common Stock	Additional Paid-in Capital	Treasury Stock	Company Stock Held By NQDC	Accumulated other comprehensive income (loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2019	[1]			179,838
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				2,172
Repurchase of common stock (in shares)				(518)
Ending balance (in shares) at Sep. 30, 2020				181,492
Beginning balance at Dec. 31, 2019	[1]	$ 3,122,381		$ 180	$ 4,832,707	$ 0	$ (9,961)	$ 20,164	$ (1,720,709)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				1	17,601
Stock-based compensation					136,688
Repurchase of common stock					(50,000)	(50,000)
Retirement of treasury stock						50,000
Common stock held by the NQDC					795		(795)
Other comprehensive income (loss)								(9,779)
Net income (loss)		837,001							837,001
Ending balance at Sep. 30, 2020		4,053,893		$ 181	4,937,791	0	(10,756)	10,385	(883,708)
Beginning balance (in shares) at Jun. 30, 2020	[1]			181,148
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				344
Repurchase of common stock (in shares)				0
Ending balance (in shares) at Sep. 30, 2020				181,492
Beginning balance at Jun. 30, 2020	[1]	3,236,679		$ 181	4,885,637	0	(10,678)	30,050	(1,668,511)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				0	7,319
Stock-based compensation					44,757
Repurchase of common stock					0	0
Retirement of treasury stock						0
Common stock held by the NQDC					78		(78)
Other comprehensive income (loss)								(19,665)
Net income (loss)		784,803							784,803
Ending balance at Sep. 30, 2020		4,053,893		$ 181	4,937,791	0	(10,756)	10,385	(883,708)
Beginning balance (in shares) at Dec. 31, 2020	[1]			181,741
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				1,827
Repurchase of common stock (in shares)				0
Ending balance (in shares) at Sep. 30, 2021				183,568
Beginning balance at Dec. 31, 2020	[1]	4,106,002	[2]	$ 182	4,993,407	0	(9,839)	(16,139)	(861,609)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				2	(11,551)
Stock-based compensation					151,500
Repurchase of common stock					0	0
Retirement of treasury stock						0
Common stock held by the NQDC					386		(386)
Other comprehensive income (loss)								26,378
Net income (loss)		(6,182)							(6,182)
Ending balance at Sep. 30, 2021		4,266,149		$ 184	5,133,742	0	(10,225)	10,239	(867,791)
Beginning balance (in shares) at Jun. 30, 2021	[1]			183,322
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans (in shares)				246
Repurchase of common stock (in shares)				0
Ending balance (in shares) at Sep. 30, 2021				183,568
Beginning balance at Jun. 30, 2021	[1]	4,241,571		$ 183	5,083,831	0	(10,207)	(939)	(831,297)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under equity incentive plans, net of tax				1	(460)
Stock-based compensation					50,353
Repurchase of common stock					0	0
Retirement of treasury stock						0
Common stock held by the NQDC					18		(18)
Other comprehensive income (loss)								11,178
Net income (loss)		(36,494)							(36,494)
Ending balance at Sep. 30, 2021		$ 4,266,149		$ 184	$ 5,133,742	$ 0	$ (10,225)	$ 10,239	$ (867,791)
[1]	The beginning balances for the nine-month periods were derived from the audited Consolidated Financial Statements included in Company’s Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on February 26, 2021.
[2]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ (6,182)	$ 837,001
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	82,053	77,814
Non-cash interest expense	3,114	14,766
Amortization of premium on investments	3,279	175
Stock-based compensation	153,372	142,125
Gain on sale of nonfinancial assets	0	(59,495)
Inventory reserves, net of stock-based compensation	0	75,609
Deferred income taxes	(12,020)	(854,199)
Unrealized foreign exchange (gain) loss	(1,347)	9,082
Non-cash changes in the fair value of contingent consideration	6,254	1,352
Other	(1,317)	388
Changes in operating assets and liabilities:
Accounts receivable, net	65,513	(32,915)
Inventory	(19,125)	(73,310)
Other current assets	27,029	32,848
Other assets	(407)	(5,543)
Accounts payable and accrued liabilities	(7,129)	(76,174)
Other long-term liabilities	269	9,225
Net cash provided by operating activities	293,356	98,749
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant and equipment	(66,840)	(83,286)
Maturities and sales of investments	502,112	345,224
Purchases of available-for-sale securities	(737,144)	(369,942)
Proceeds from sale of nonfinancial assets	0	67,159
Purchase of intangible assets	(8,026)	(14,369)
Investment in convertible note	0	(8,709)
Other	(994)	(725)
Net cash used in investing activities	(310,892)	(64,648)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercises of awards under equity incentive plans	32,877	60,268
Taxes paid related to net share settlement of equity awards	(44,428)	(42,667)
Repurchase of common stock	0	(50,000)
Proceeds from convertible senior subordinated note offering, net	0	585,752
Principal repayments of financing leases	(2,492)	(6,080)
Other	(401)	0
Net cash provided by (used in) financing activities	(14,444)	547,273
Effect of exchange rate changes on cash	(35)	(3,145)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(32,015)	578,229
Cash and cash equivalents:
Beginning of period	649,158	437,446
End of period	617,143	1,015,675
SUPPLEMENTAL CASH FLOW DISCLOSURES:
Cash paid for income taxes	15,531	4,355
Cash paid for interest	6,673	5,615
SUPPLEMENTAL CASH FLOW DISCLOSURES FOR NON-CASH INVESTING AND FINANCING ACTIVITIES:
Decrease in accounts payable and accrued liabilities related to fixed assets	(7,690)	(13,281)
Increase (decrease) in accounts payable and accrued liabilities related to intangible assets	$ 9,389	$ (3,043)

NATURE OF OPERATIONS

NATURE OF OPERATIONS	9 Months Ended
	Sep. 30, 2021
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 products and multiple clinical and preclinical product candidates for the treatment of various diseases. Voxzogo (formerly known as vosoritide) was granted marketing approval in the European Union (EU) on August 27, 2021. 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	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION The accompanying Condensed Consolidated Financial Statements have been prepared pursuant to United States generally accepted accounting principles (U.S. GAAP) and the rules and regulations of the Securities and Exchange Commission (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, 2020 included in the Company’s Annual Report on Form 10-K. The Condensed Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany transactions have been eliminated. The results of operations for the three and nine months ended September 30, 2021 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2021 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 (referred to as COVID-19) pandemic could continue to 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 remain uncertain at this time, particularly as virus variants continue to spread. 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	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES There have been no material changes to the Company’s significant accounting policies during the nine months ended September 30, 2021, as compared to the significant accounting policies disclosed in Note 3 – Summary of Significant Accounting Policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020.

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	9 Months Ended
	Sep. 30, 2021
Accounting Standards Update and Change in Accounting Principle [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTSThere have been no new accounting pronouncements adopted by the Company or new accounting pronouncements issued by the Financial Accounting Standards Board during the nine months ended September 30, 2021, 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, 2020, that the Company believes are of significance or potential significance to the Company.

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
FINANCIAL INSTRUMENTS	FINANCIAL INSTRUMENTS All marketable securities were classified as available-for-sale at September 30, 2021 and December 31, 2020. The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category for each period presented: September 30, 2021 Amortized Cost Gross Gross Aggregate Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 294,209 $ — $ — $ 294,209 $ 294,209 $ — $ — Level 2: Money market instruments 291,735 — — 291,735 291,735 — — Corporate debt securities 560,004 1,230 (198) 561,036 703 177,468 382,865 U.S. government agency securities 210,444 416 (7) 210,853 12,999 161,207 36,647 Commercial paper 129,818 1 (1) 129,818 17,497 112,321 — Asset-backed securities 55,182 26 (23) 55,185 — 8,272 46,913 Foreign and other 3,114 150 (6) 3,258 — 3,065 193 Subtotal 1,250,297 1,823 (235) 1,251,885 322,934 462,333 466,618 Total $ 1,544,506 $ 1,823 $ (235) $ 1,546,094 $ 617,143 $ 462,333 $ 466,618 December 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 $ 370,325 $ — $ — $ 370,325 $ 370,325 $ — $ — Level 2: Money market instruments 264,833 — — 264,833 264,833 — — Corporate debt securities 413,137 3,261 (8) 416,390 — 220,551 195,839 U.S. government agency securities 265,298 1,555 (1) 266,852 14,000 192,488 60,364 Asset-backed securities 31,659 85 (2) 31,742 — 3,189 28,553 Foreign and other 549 168 — 717 — — 717 Subtotal 975,476 5,069 (11) 980,534 278,833 416,228 285,473 Total $ 1,345,801 $ 5,069 $ (11) $ 1,350,859 $ 649,158 $ 416,228 $ 285,473 (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 September 30, 2021, the Company had the ability and intent to hold all investments that were in an unrealized loss position until maturity. The Company considered its intent and ability to hold the securities until recovery of amortized cost basis, 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. The Company has certain investments in non-marketable equity securities, measured using unobservable valuation inputs and remeasured on a nonrecurring basis, which are collectively considered strategic investments. As of September 30, 2021 and

SUPPLEMENTAL BALANCE SHEET INFO

SUPPLEMENTAL BALANCE SHEET INFORMATION	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
SUPPLEMENTAL BALANCE SHEET INFORMATION	SUPPLEMENTAL BALANCE SHEET INFORMATION Inventory consisted of the following: September 30, December 31, Raw materials $ 75,328 $ 76,673 Work-in-process 412,434 308,286 Finished goods 261,644 313,589 Total inventory $ 749,406 $ 698,548 Inventory as of September 30, 2021 included $4.8 million of Voxzogo pre-launch manufacturing-related costs incurred during the third quarter of 2021 that are intended for the U.S. Voxzogo, which was granted marketing approval in the EU on August 27, 2021, is still a product candidate in other regions, including the U.S., for the treatment of achondroplasia in children, the most common form of disproportionate short stature in humans. The Company must receive marketing approval from the U.S. Food and Drug Administration (FDA) before the Voxzogo inventory can be sold commercially in the U.S. Starting in 2021, the Company believed that material uncertainties related to the ultimate regulatory approval of Voxzogo had 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, historical experience, as well as potential impediments to the approval process such as product safety or efficacy, as well as commercialization and marketplace trends. 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, 2020 for additional information related to the Company’s policies on inventory produced prior to regulatory approval. Property, Plant and Equipment, Net consisted of the following: September 30, December 31, Property, plant and equipment, gross $ 1,724,702 $ 1,668,066 Accumulated depreciation (699,915) (635,595) Total property, plant and equipment, net $ 1,024,787 $ 1,032,471 Depreciation expense, net of amounts capitalized into inventory, for the three and nine months ended September 30, 2021 was $11.4 million and $35.7 million, respectively. Depreciation expense, net of amounts capitalized into inventory, for the three and nine months ended September 30, 2020 was $11.1 million and $31.1 million, respectively. Intangible Assets, Net consisted of the following: September 30, December 31, Finite-lived intangible assets $ 661,781 $ 644,087 Less: Accumulated amortization (273,294) (226,816) Net carrying value $ 388,487 $ 417,271 Accounts Payable and Accrued Liabilities consisted of the following: September 30, December 31, Accounts payable and accrued operating expenses $ 203,321 $ 191,429 Accrued compensation expense 158,130 165,023 Accrued rebates payable 68,329 65,526 Accrued royalties payable 14,512 17,155 Lease liabilities 9,659 11,754 Forward foreign currency exchange contracts 5,323 17,798 Value added taxes payable 1,412 9,562 Accrued income taxes 564 9,661 Other 5,461 4,640 Total accounts payable and accrued liabilities $ 466,711 $ 492,548

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2021
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 – Summary of Significant Accounting Policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. 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 September 30, 2021 and December 31, 2020. Other than the Company’s fixed-rate convertible debt disclosed in Note 9 – Debt , there were no financial assets or liabilities that were remeasured using a quoted price in active markets for identical assets (Level 1) as of September 30, 2021 or December 31, 2020. Fair Value Measurements as of September 30, 2021 Significant Other Significant Total Assets: Other current assets: NQDC Plan assets $ 2,089 $ — $ 2,089 Other assets: NQDC Plan assets 22,521 — 22,521 Restricted investments (1) 2,835 — 2,835 Total other assets 25,356 — 25,356 Total assets $ 27,445 $ — $ 27,445 Liabilities: Current liabilities: NQDC Plan liability $ 2,089 $ — $ 2,089 Contingent consideration — 48,187 48,187 Total current liabilities 2,089 48,187 50,276 Other long-term liabilities: NQDC Plan liability 22,521 — 22,521 Contingent consideration — 15,204 15,204 Total other long-term liabilities 22,521 15,204 37,725 Total liabilities $ 24,610 $ 63,391 $ 88,001 Fair Value Measurements as of December 31, 2020 Significant Other Significant Total Assets: Other current assets: NQDC Plan assets $ 2,415 $ — $ 2,415 Other assets: NQDC Plan assets 19,962 — 19,962 Restricted investments (1) 4,487 — 4,487 Total other assets 24,449 — 24,449 Total assets $ 26,864 $ — $ 26,864 Liabilities: Current liabilities: NQDC Plan liability $ 2,415 $ — $ 2,415 Other long-term liabilities: NQDC Plan liability 19,962 — 19,962 Contingent consideration — 60,130 60,130 Total other long-term liabilities 19,962 60,130 80,092 Total liabilities $ 22,377 $ 60,130 $ 82,507 (1) The restricted investments at September 30, 2021 and December 31, 2020 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 and nine months ended September 30, 2021. Liabilities measured at fair value using Level 3 inputs primarily consisted of contingent consideration. The following tables represent a roll-forward of contingent consideration. Contingent consideration as of December 31, 2020 $ 60,130 Changes in the fair value of contingent consideration 6,254 Foreign exchange remeasurement of Euro denominated contingent consideration (2,993) Contingent consideration as of September 30, 2021 $ 63,391

DERIVATIVE INSTRUMENTS AND HEDG

DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES	DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIESThe Company uses foreign currency exchange forward contracts (forward contracts) to protect against the reduction in value of forecasted foreign currency cash flows resulting from product revenues, royalty revenues and operating expenses denominated in currencies other than the U.S. Dollar (USD), primarily the Euro. Certain of these forward contracts are designated as cash flows hedges and have maturities of up to two years. The Company also enters into forward contracts to manage foreign exchange risk related to asset or liability positions denominated in currencies other than USD. Such forward contracts are considered to be economic hedges, are not designated as hedging instruments and have maturities of up to three months. The Company does not use derivative instruments for speculative trading purposes. The Company is exposed to counterparty credit risk on its derivatives. The Company has established and maintains strict counterparty credit guidelines and enters into hedging agreements with financial institutions that are investment grade or better to minimize the Company’s exposure to potential defaults. The Company is not required to pledge collateral under these agreements. The following table summarizes the aggregate notional amounts for the Company’s derivatives outstanding as of the periods presented. Foreign Exchange Contracts September 30, 2021 December 31, 2020 Derivatives designated as hedging instruments: Sell $ 654,516 $ 782,327 Purchase $ 168,080 $ 189,540 Derivatives not designated as hedging instruments: Sell $ 77,040 $ 98,343 Purchase $ 37,285 $ 12,277 The fair value carrying amounts of the Company’s derivatives, as classified within the fair value hierarchy, were as follows: Balance Sheet Location September 30, 2021 December 31, 2020 Derivatives designated as hedging instruments: Asset Derivatives - Level 2 (1) Other current assets $ 11,883 $ 6,268 Other assets 4,320 3,148 Subtotal $ 16,203 $ 9,416 Liability Derivatives - Level 2 (1) Accounts payable and accrued liabilities $ 5,257 $ 17,551 Other long-term liabilities 1,486 11,020 Subtotal $ 6,743 $ 28,571 Derivatives not designated as hedging instruments: Asset Derivatives - Level 2 (1) Other current assets $ 252 $ 84 Liability Derivatives - Level 2 (1) Accounts payable and accrued liabilities $ 66 $ 247 Total Derivatives Assets $ 16,455 $ 9,500 Total Derivatives Liabilities $ 6,809 $ 28,818 (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, 2020. 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 September 30, 2021 2020 Derivatives Designated as Cash Flow Hedging Instruments Cash Flow Hedging Gains (Losses) Cash Flow Hedging Gains (Losses) Net product revenues as reported $ 393,840 $ 401 $ 460,741 $ 2,693 Operating expenses as reported $ 461,961 $ (268) $ 532,725 $ (815) Derivatives Not Designated as Hedging Instruments Gains (Losses) Recognized in Earnings Gains (Losses) Recognized in Earnings Operating expenses $ 1,302 $ 4,166 Nine Months Ended September 30, 2021 2020 Derivatives Designated as Cash Flow Hedging Instruments Cash Flow Hedging Gains (Losses) Cash Flow Hedging Gains (Losses) Net product revenues as reported $ 1,348,279 $ (5,034) $ 1,368,816 $ 17,301 Operating expenses as reported $ 1,412,926 $ 81 $ 1,400,263 $ (4,274) Derivatives Not Designated as Hedging Instruments Gains (Losses) Recognized in Earnings Gains (Losses) Recognized in Earnings Operating expenses $ 2,310 $ 9,600 As of September 30, 2021, the Company expects to reclassify unrealized gains of $6.2 million from Accumulated Other Comprehensive Income (AOCI) to earnings as the forecasted revenues and operating expense transactions occur over the next 12 months. For additional discussion of balances in AOCI see Note 10 – Accumulated Other Comprehensive Income .

DEBT

DEBT	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
DEBT	DEBT Convertible Notes As of September 30, 2021, the Company had outstanding fixed-rate notes with varying maturities for an undiscounted aggregate principal amount of $1.1 billion (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: September 30, December 31, 1.25% senior subordinated convertible notes due in May 2027 (the 2027 Notes) $ 600,000 $ 600,000 Unamortized discount net of deferred offering costs (11,478) (12,995) 2027 Notes, net 588,522 587,005 0.599% senior subordinated convertible notes due in August 2024 (the 2024 Notes) 495,000 495,000 Unamortized discount net of deferred offering costs (5,429) (6,860) 2024 Notes, net 489,571 488,140 Total convertible debt, net $ 1,078,093 $ 1,075,145 Fair value of fixed rate convertible debt (1) : 2027 Notes $ 600,858 $ 627,090 2024 Notes 510,954 530,714 Total fair value of fixed rate convertible debt $ 1,111,812 $ 1,157,804 (1) 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, 2020. Interest expense on the Company’s convertible debt consisted of the following: Three Months Ended Nine Months Ended September 30, 2021 2020 2021 2020 Coupon interest expense $ 2,617 $ 4,255 $ 7,849 $ 9,443 Accretion of discount on convertible notes 835 4,696 2,503 13,201 Amortization of debt issuance costs 148 535 445 1,565 Total interest expense on convertible debt $ 3,600 $ 9,486 $ 10,797 $ 24,209 See Note 13 - Debt included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 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 which includes a letter of credit subfacility and a swingline loan subfacility. The credit facility is intended to finance ongoing working capital needs and for other general corporate purposes. In May 2021, the Company entered into an amendment agreement in respect of the credit facility, extending the maturity date from October 19, 2021 to May 28, 2024, among other changes. The amended credit facility contains financial covenants including a maximum leverage ratio and a minimum interest coverage ratio. As of September 30, 2021, there were no amounts outstanding under the credit facility and the Company and certain of its subsidiaries that serve as guarantors were in compliance with all covenants.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following tables summarize changes in the accumulated balances for each component of Accumulated Other Comprehensive Income (Loss) (AOCI), including current-period other comprehensive income (loss) and reclassifications out of AOCI, for the periods presented. Three Months Ended September 30, 2021 Unrealized Gains Unrealized Gains Other Total AOCI balance at June 30, 2021 $ (2,760) $ 1,821 $ — $ (939) Other comprehensive income (loss) before 11,914 (786) — 11,128 Less: gain (loss) reclassified from AOCI 133 — — 133 Tax effect — 183 — 183 Net current-period other comprehensive income (loss) 11,781 (603) — 11,178 AOCI balance at September 30, 2021 $ 9,021 $ 1,218 $ — $ 10,239 Three Months Ended September 30, 2020 Unrealized Gains Unrealized Gains Other Total AOCI balance at June 30, 2020 $ 22,963 $ 7,087 $ — $ 30,050 Other comprehensive income (loss) before (16,094) (2,201) — (18,295) Less: gain (loss) reclassified from AOCI 1,878 — — 1,878 Tax effect — 508 — 508 Net current-period other comprehensive income (loss) (17,972) (1,693) — (19,665) AOCI balance at September 30, 2020 $ 4,991 $ 5,394 $ — $ 10,385 Nine Months Ended September 30, 2021 Unrealized Gains Unrealized Gains Other Total AOCI balance at December 31, 2020 $ (20,028) $ 3,889 $ — $ (16,139) Other comprehensive income (loss) before 24,096 (3,470) — 20,626 Less: gain (loss) reclassified from AOCI (4,953) — — (4,953) Tax effect — 799 — 799 Net current-period other comprehensive income (loss) 29,049 (2,671) — 26,378 AOCI balance at September 30, 2021 $ 9,021 $ 1,218 $ — $ 10,239 Nine Months Ended September 30, 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 1,404 2,379 15 3,798 Less: gain (loss) reclassified from AOCI 13,027 — — 13,027 Tax effect — (550) — (550) Net current-period other comprehensive income (loss) (11,623) 1,829 15 (9,779) AOCI balance at September 30, 2020 $ 4,991 $ 5,394 $ — $ 10,385 For additional discussion of reclassifications from AOCI see Note 8 – Derivative Instruments and Hedging Strategies .

REVENUE, CREDIT CONCENTRATIONS

REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION	9 Months Ended
	Sep. 30, 2021
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 Sanofi Genzyme (Genzyme) who markets and sells Aldurazyme worldwide. 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 Nine Months Ended 2021 2020 2021 2020 Total revenues by geographic region: United States $ 196,239 $ 252,948 $ 608,670 $ 729,672 Europe 115,497 121,158 450,016 375,453 Latin America 38,958 44,064 140,911 141,852 Rest of world 58,048 58,614 196,868 161,361 Total revenues $ 408,742 $ 476,784 $ 1,396,465 $ 1,408,338 The following table disaggregates total Net Product Revenues by product. Three Months Ended Nine Months Ended 2021 2020 2021 2020 Net product revenues by product: Vimizim $ 136,744 $ 147,891 $ 466,697 $ 401,789 Naglazyme 71,172 76,323 297,321 271,585 Kuvan 67,687 123,993 217,257 368,604 Palynziq 60,729 46,092 173,702 121,354 Brineura 32,984 25,455 90,641 75,223 Voxzogo 144 — 144 — Firdapse — — — 1,316 Total net product revenues marketed by the Company $ 369,460 $ 419,754 $ 1,245,762 $ 1,239,871 Aldurazyme net product revenues marketed by Genzyme 24,380 40,987 $ 102,517 $ 128,945 Total net product revenues $ 393,840 $ 460,741 $ 1,348,279 $ 1,368,816 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 Nine Months Ended 2021 2020 2021 2020 United States $ 166,554 $ 203,892 $ 491,028 $ 582,734 Europe 108,568 115,548 424,144 360,718 Latin America 38,958 44,064 140,911 141,852 Rest of world 55,380 56,250 189,679 154,567 Total net product revenues marketed by the Company $ 369,460 $ 419,754 $ 1,245,762 $ 1,239,871 Aldurazyme net product revenues marketed by Genzyme 24,380 40,987 102,517 128,945 Total net product revenues $ 393,840 $ 460,741 $ 1,348,279 $ 1,368,816 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 Nine Months Ended 2021 2020 2021 2020 Customer A 20 % 16 % 17 % 15 % Customer B 16 % 14 % 14 % 14 % Customer C 11 % 11 % 10 % 12 % Total 47 % 41 % 41 % 41 % On a consolidated basis, two customers accounted for 31% and 14% of the Company’s September 30, 2021 accounts receivable balance, respectively, compared to December 31, 2020, when two customers accounted for 24% and 22% of the accounts receivable balance, respectively. As of September 30, 2021, and December 31, 2020, the accounts receivable balance for Genzyme included $83.9 million and $72.1 million, respectively, of unbilled accounts receivable, which becomes payable to the Company when the product is sold through by Genzyme. The Company does not require collateral from its customers, but does perform periodic credit evaluations of its customers’ financial condition and requires prepayments in certain circumstances. The COVID-19 pandemic continues to affect economies and business around the world. The Company’s global revenue sources, mostly in the form of demand interruptions such as missed patient infusions and delayed treatment starts for new patients, and its business operations were impacted by the COVID-19 pandemic during the nine months ended September 30, 2021 and 2020, and the Company anticipates a continued impact due to COVID-19 on its financial results in the remainder of 2021. The extent and duration of such effects remain uncertain and difficult to predict, particularly as virus variants continue to spread. The Company is actively monitoring and managing its response and assessing actual and potential impacts to its operating results and financial condition, as well as developments in its business, which could further impact developments, trends and expectations. See the risk factor related to the impact of the coronavirus pandemic, “The COVID-19 pandemic could continue to materially adversely affect our business, results of operations and financial condition.” described in “Risk Factors” in Part II, Item 1A of this Quarterly Report, for additional details on the impact of the COVID-19 pandemic. 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 effects of the impact of the ongoing COVID-19 pandemic may cause customers in those countries to delay payment or be unable to pay for the Company’s products. The Company believes that the allowances for doubtful accounts related to these countries, if any, are 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	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATIONThe 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 Nine Months Ended 2021 2020 2021 2020 Cost of sales $ 4,339 $ 10,342 $ 16,907 $ 20,381 Research and development 17,866 15,705 56,199 45,333 Selling, general and administrative 26,821 24,122 80,266 76,411 Total stock-based compensation expense $ 49,026 $ 50,169 $ 153,372 $ 142,125

NET INCOME (LOSS) PER COMMON SH

NET INCOME (LOSS) PER COMMON SHARE	9 Months Ended
	Sep. 30, 2021
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, the Company’s common stock held by the NQDC and contingent issuances of common stock related to the Company’s convertible debt. The following table sets forth the computation of basic and diluted earnings per common share (common shares in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Numerator: Net Income (loss), basic $ (36,494) $ 784,803 $ (6,182) $ 837,001 Add: Interest on convertible notes — 7,070 — 18,333 Net Income (loss), diluted $ (36,494) $ 791,873 $ (6,182) $ 855,334 Denominator: Weighted-average common shares outstanding, basic 183,214 181,142 182,616 180,592 Effect of dilutive securities: Options to purchase common stock — 1,731 — 1,728 Common stock issuable under the 2020 notes — 3,983 — 3,983 Common stock issuable under the 2024 notes — 3,970 — 3,970 Common stock issuable under the 2027 notes — 4,365 — 2,373 Unvested RSUs — 1,926 — 1,765 Common stock potentially issuable for ESPP purchases — 346 — 337 The Company’s common stock held by the NQDC — 211 — 211 Weighted-average common shares outstanding, diluted 183,214 197,674 182,616 194,959 Net income (loss) per common share, basic $ (0.20) $ 4.33 $ (0.03) $ 4.63 Net income (loss) per common share, diluted $ (0.20) $ 4.01 $ (0.03) $ 4.39 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 basic and diluted income (loss) per common share as they were anti-dilutive (in thousands): Three Months Ended September 30, Nine Months Ended 2021 2020 2021 2020 Options to purchase common stock 6,649 5,172 6,649 5,175 Common stock issuable under the 2024 Notes 3,970 — 3,970 — Common stock issuable under the 2027 Notes 4,365 — 4,365 — Unvested RSUs 5,292 2,900 5,292 3,060 Common stock potentially issuable for ESPP purchases 582 193 582 204 The Company’s common stock held by the NQDC 197 — 197 — Total number of potentially issuable shares 21,055 8,265 21,055 8,439 The Company’s 1.50% senior subordinated convertible notes due in October 2020 (the 2020 Notes) matured on October 15, 2020 and were settled in cash. The potential effect of the capped call transactions and potential shares issuable under the 2020 Notes were excluded from the calculation of diluted net income (loss) per share in the three and nine months ended September 30, 2020, as the Company’s closing price on September 30, 2020 did not exceed the conversion price of $94.15 per share. There is no similar capped call transaction associated with the 2024 Notes or the 2027 Notes.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2021
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 September 30, 2021, the Company was subject to contingent payments totaling approximately $708.8 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, $70.0 million were considered probable and comprised of commercial milestones related to the acquisition of certain rights and other assets with respect to Kuvan and Palynziq from a third party, $405.5 million were considered reasonably possible and primarily related to development milestones and $233.3 million were considered remote as the Company is no longer developing the related programs. As of September 30, 2021, the fair value of contingent liabilities recorded on the Company’s Condensed Consolidated Balance Sheet was $63.4 million of which $48.2 million was short term. See Note 7 – Fair Value Measurements to these Condensed Consolidated Financial Statements for further information regarding the fair value of the Company’s contingent consideration. Other Commitments The Company uses experts and laboratories at universities and other institutions to perform certain research and development (R&D) activities. These amounts are included as R&D expense as services are provided. 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 September 30, 2021, such commitments and other minimum contractual obligations for clinical and post-marketing services were estimated at approximately $107.7 million. The Company has also licensed technology, for which it is required to pay royalties upon future sales, subject to certain annual minimums.

BASIS OF PRESENTATION (Policies

BASIS OF PRESENTATION (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	The accompanying Condensed Consolidated Financial Statements have been prepared pursuant to United States generally accepted accounting principles (U.S. GAAP) and the rules and regulations of the Securities and Exchange Commission (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, 2020 included in the Company’s Annual Report on Form 10-K. The Condensed Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany transactions have been eliminated. The results of operations for the three and nine months ended September 30, 2021 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2021 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 (referred to as COVID-19) pandemic could continue to 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 remain uncertain at this time, particularly as virus variants continue to spread. As events continue to evolve and additional information becomes available, the Company’s estimates may change materially in future periods.

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2021
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: September 30, 2021 Amortized Cost Gross Gross Aggregate Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 294,209 $ — $ — $ 294,209 $ 294,209 $ — $ — Level 2: Money market instruments 291,735 — — 291,735 291,735 — — Corporate debt securities 560,004 1,230 (198) 561,036 703 177,468 382,865 U.S. government agency securities 210,444 416 (7) 210,853 12,999 161,207 36,647 Commercial paper 129,818 1 (1) 129,818 17,497 112,321 — Asset-backed securities 55,182 26 (23) 55,185 — 8,272 46,913 Foreign and other 3,114 150 (6) 3,258 — 3,065 193 Subtotal 1,250,297 1,823 (235) 1,251,885 322,934 462,333 466,618 Total $ 1,544,506 $ 1,823 $ (235) $ 1,546,094 $ 617,143 $ 462,333 $ 466,618 December 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 $ 370,325 $ — $ — $ 370,325 $ 370,325 $ — $ — Level 2: Money market instruments 264,833 — — 264,833 264,833 — — Corporate debt securities 413,137 3,261 (8) 416,390 — 220,551 195,839 U.S. government agency securities 265,298 1,555 (1) 266,852 14,000 192,488 60,364 Asset-backed securities 31,659 85 (2) 31,742 — 3,189 28,553 Foreign and other 549 168 — 717 — — 717 Subtotal 975,476 5,069 (11) 980,534 278,833 416,228 285,473 Total $ 1,345,801 $ 5,069 $ (11) $ 1,350,859 $ 649,158 $ 416,228 $ 285,473 (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

SUPPLEMENTAL BALANCE SHEET IN_2

SUPPLEMENTAL BALANCE SHEET INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Inventory	Inventory consisted of the following: September 30, December 31, Raw materials $ 75,328 $ 76,673 Work-in-process 412,434 308,286 Finished goods 261,644 313,589 Total inventory $ 749,406 $ 698,548
Schedule of Property Plant and Equipment Net	Property, Plant and Equipment, Net consisted of the following: September 30, December 31, Property, plant and equipment, gross $ 1,724,702 $ 1,668,066 Accumulated depreciation (699,915) (635,595) Total property, plant and equipment, net $ 1,024,787 $ 1,032,471
Schedule of Intangible Assets	Intangible Assets, Net consisted of the following: September 30, December 31, Finite-lived intangible assets $ 661,781 $ 644,087 Less: Accumulated amortization (273,294) (226,816) Net carrying value $ 388,487 $ 417,271
Schedule of Accounts Payable and Accrued Liabilities	Accounts Payable and Accrued Liabilities consisted of the following: September 30, December 31, Accounts payable and accrued operating expenses $ 203,321 $ 191,429 Accrued compensation expense 158,130 165,023 Accrued rebates payable 68,329 65,526 Accrued royalties payable 14,512 17,155 Lease liabilities 9,659 11,754 Forward foreign currency exchange contracts 5,323 17,798 Value added taxes payable 1,412 9,562 Accrued income taxes 564 9,661 Other 5,461 4,640 Total accounts payable and accrued liabilities $ 466,711 $ 492,548

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2021
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 September 30, 2021 and December 31, 2020. Other than the Company’s fixed-rate convertible debt disclosed in Note 9 – Debt , there were no financial assets or liabilities that were remeasured using a quoted price in active markets for identical assets (Level 1) as of September 30, 2021 or December 31, 2020. Fair Value Measurements as of September 30, 2021 Significant Other Significant Total Assets: Other current assets: NQDC Plan assets $ 2,089 $ — $ 2,089 Other assets: NQDC Plan assets 22,521 — 22,521 Restricted investments (1) 2,835 — 2,835 Total other assets 25,356 — 25,356 Total assets $ 27,445 $ — $ 27,445 Liabilities: Current liabilities: NQDC Plan liability $ 2,089 $ — $ 2,089 Contingent consideration — 48,187 48,187 Total current liabilities 2,089 48,187 50,276 Other long-term liabilities: NQDC Plan liability 22,521 — 22,521 Contingent consideration — 15,204 15,204 Total other long-term liabilities 22,521 15,204 37,725 Total liabilities $ 24,610 $ 63,391 $ 88,001 Fair Value Measurements as of December 31, 2020 Significant Other Significant Total Assets: Other current assets: NQDC Plan assets $ 2,415 $ — $ 2,415 Other assets: NQDC Plan assets 19,962 — 19,962 Restricted investments (1) 4,487 — 4,487 Total other assets 24,449 — 24,449 Total assets $ 26,864 $ — $ 26,864 Liabilities: Current liabilities: NQDC Plan liability $ 2,415 $ — $ 2,415 Other long-term liabilities: NQDC Plan liability 19,962 — 19,962 Contingent consideration — 60,130 60,130 Total other long-term liabilities 19,962 60,130 80,092 Total liabilities $ 22,377 $ 60,130 $ 82,507 (1) The restricted investments at September 30, 2021 and December 31, 2020 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	Liabilities measured at fair value using Level 3 inputs primarily consisted of contingent consideration. The following tables represent a roll-forward of contingent consideration. Contingent consideration as of December 31, 2020 $ 60,130 Changes in the fair value of contingent consideration 6,254 Foreign exchange remeasurement of Euro denominated contingent consideration (2,993) Contingent consideration as of September 30, 2021 $ 63,391

DERIVATIVE INSTRUMENTS AND HE_2

DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES (Tables)	9 Months Ended
	Sep. 30, 2021
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 September 30, 2021 December 31, 2020 Derivatives designated as hedging instruments: Asset Derivatives - Level 2 (1) Other current assets $ 11,883 $ 6,268 Other assets 4,320 3,148 Subtotal $ 16,203 $ 9,416 Liability Derivatives - Level 2 (1) Accounts payable and accrued liabilities $ 5,257 $ 17,551 Other long-term liabilities 1,486 11,020 Subtotal $ 6,743 $ 28,571 Derivatives not designated as hedging instruments: Asset Derivatives - Level 2 (1) Other current assets $ 252 $ 84 Liability Derivatives - Level 2 (1) Accounts payable and accrued liabilities $ 66 $ 247 Total Derivatives Assets $ 16,455 $ 9,500 Total Derivatives Liabilities $ 6,809 $ 28,818 (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, 2020.
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 September 30, 2021 2020 Derivatives Designated as Cash Flow Hedging Instruments Cash Flow Hedging Gains (Losses) Cash Flow Hedging Gains (Losses) Net product revenues as reported $ 393,840 $ 401 $ 460,741 $ 2,693 Operating expenses as reported $ 461,961 $ (268) $ 532,725 $ (815) Derivatives Not Designated as Hedging Instruments Gains (Losses) Recognized in Earnings Gains (Losses) Recognized in Earnings Operating expenses $ 1,302 $ 4,166 Nine Months Ended September 30, 2021 2020 Derivatives Designated as Cash Flow Hedging Instruments Cash Flow Hedging Gains (Losses) Cash Flow Hedging Gains (Losses) Net product revenues as reported $ 1,348,279 $ (5,034) $ 1,368,816 $ 17,301 Operating expenses as reported $ 1,412,926 $ 81 $ 1,400,263 $ (4,274) Derivatives Not Designated as Hedging Instruments Gains (Losses) Recognized in Earnings Gains (Losses) Recognized in Earnings Operating expenses $ 2,310 $ 9,600
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Summary of Derivatives Designated as Hedging Instruments Outstanding	The following table summarizes the aggregate notional amounts for the Company’s derivatives outstanding as of the periods presented. Foreign Exchange Contracts September 30, 2021 December 31, 2020 Derivatives designated as hedging instruments: Sell $ 654,516 $ 782,327 Purchase $ 168,080 $ 189,540 Derivatives not designated as hedging instruments: Sell $ 77,040 $ 98,343 Purchase $ 37,285 $ 12,277

DEBT (Tables)

DEBT (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Summary of Convertible Debt	The following table summarizes information regarding the Company’s convertible debt: September 30, December 31, 1.25% senior subordinated convertible notes due in May 2027 (the 2027 Notes) $ 600,000 $ 600,000 Unamortized discount net of deferred offering costs (11,478) (12,995) 2027 Notes, net 588,522 587,005 0.599% senior subordinated convertible notes due in August 2024 (the 2024 Notes) 495,000 495,000 Unamortized discount net of deferred offering costs (5,429) (6,860) 2024 Notes, net 489,571 488,140 Total convertible debt, net $ 1,078,093 $ 1,075,145 Fair value of fixed rate convertible debt (1) : 2027 Notes $ 600,858 $ 627,090 2024 Notes 510,954 530,714 Total fair value of fixed rate convertible debt $ 1,111,812 $ 1,157,804 (1) 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, 2020.
Summary of Interest Expense on Debt	Interest expense on the Company’s convertible debt consisted of the following: Three Months Ended Nine Months Ended September 30, 2021 2020 2021 2020 Coupon interest expense $ 2,617 $ 4,255 $ 7,849 $ 9,443 Accretion of discount on convertible notes 835 4,696 2,503 13,201 Amortization of debt issuance costs 148 535 445 1,565 Total interest expense on convertible debt $ 3,600 $ 9,486 $ 10,797 $ 24,209

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
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 Accumulated Other Comprehensive Income (Loss) (AOCI), including current-period other comprehensive income (loss) and reclassifications out of AOCI, for the periods presented. Three Months Ended September 30, 2021 Unrealized Gains Unrealized Gains Other Total AOCI balance at June 30, 2021 $ (2,760) $ 1,821 $ — $ (939) Other comprehensive income (loss) before 11,914 (786) — 11,128 Less: gain (loss) reclassified from AOCI 133 — — 133 Tax effect — 183 — 183 Net current-period other comprehensive income (loss) 11,781 (603) — 11,178 AOCI balance at September 30, 2021 $ 9,021 $ 1,218 $ — $ 10,239 Three Months Ended September 30, 2020 Unrealized Gains Unrealized Gains Other Total AOCI balance at June 30, 2020 $ 22,963 $ 7,087 $ — $ 30,050 Other comprehensive income (loss) before (16,094) (2,201) — (18,295) Less: gain (loss) reclassified from AOCI 1,878 — — 1,878 Tax effect — 508 — 508 Net current-period other comprehensive income (loss) (17,972) (1,693) — (19,665) AOCI balance at September 30, 2020 $ 4,991 $ 5,394 $ — $ 10,385 Nine Months Ended September 30, 2021 Unrealized Gains Unrealized Gains Other Total AOCI balance at December 31, 2020 $ (20,028) $ 3,889 $ — $ (16,139) Other comprehensive income (loss) before 24,096 (3,470) — 20,626 Less: gain (loss) reclassified from AOCI (4,953) — — (4,953) Tax effect — 799 — 799 Net current-period other comprehensive income (loss) 29,049 (2,671) — 26,378 AOCI balance at September 30, 2021 $ 9,021 $ 1,218 $ — $ 10,239 Nine Months Ended September 30, 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 1,404 2,379 15 3,798 Less: gain (loss) reclassified from AOCI 13,027 — — 13,027 Tax effect — (550) — (550) Net current-period other comprehensive income (loss) (11,623) 1,829 15 (9,779) AOCI balance at September 30, 2020 $ 4,991 $ 5,394 $ — $ 10,385

REVENUE, CREDIT CONCENTRATION_2

REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2021
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 Sanofi Genzyme (Genzyme) who markets and sells Aldurazyme worldwide. 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 Nine Months Ended 2021 2020 2021 2020 Total revenues by geographic region: United States $ 196,239 $ 252,948 $ 608,670 $ 729,672 Europe 115,497 121,158 450,016 375,453 Latin America 38,958 44,064 140,911 141,852 Rest of world 58,048 58,614 196,868 161,361 Total revenues $ 408,742 $ 476,784 $ 1,396,465 $ 1,408,338
Schedule of Net Product Revenues by Product	The following table disaggregates total Net Product Revenues by product. Three Months Ended Nine Months Ended 2021 2020 2021 2020 Net product revenues by product: Vimizim $ 136,744 $ 147,891 $ 466,697 $ 401,789 Naglazyme 71,172 76,323 297,321 271,585 Kuvan 67,687 123,993 217,257 368,604 Palynziq 60,729 46,092 173,702 121,354 Brineura 32,984 25,455 90,641 75,223 Voxzogo 144 — 144 — Firdapse — — — 1,316 Total net product revenues marketed by the Company $ 369,460 $ 419,754 $ 1,245,762 $ 1,239,871 Aldurazyme net product revenues marketed by Genzyme 24,380 40,987 $ 102,517 $ 128,945 Total net product revenues $ 393,840 $ 460,741 $ 1,348,279 $ 1,368,816
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 Nine Months Ended 2021 2020 2021 2020 United States $ 166,554 $ 203,892 $ 491,028 $ 582,734 Europe 108,568 115,548 424,144 360,718 Latin America 38,958 44,064 140,911 141,852 Rest of world 55,380 56,250 189,679 154,567 Total net product revenues marketed by the Company $ 369,460 $ 419,754 $ 1,245,762 $ 1,239,871 Aldurazyme net product revenues marketed by Genzyme 24,380 40,987 102,517 128,945 Total net product revenues $ 393,840 $ 460,741 $ 1,348,279 $ 1,368,816
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 Nine Months Ended 2021 2020 2021 2020 Customer A 20 % 16 % 17 % 15 % Customer B 16 % 14 % 14 % 14 % Customer C 11 % 11 % 10 % 12 % Total 47 % 41 % 41 % 41 %

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2021
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 Nine Months Ended 2021 2020 2021 2020 Cost of sales $ 4,339 $ 10,342 $ 16,907 $ 20,381 Research and development 17,866 15,705 56,199 45,333 Selling, general and administrative 26,821 24,122 80,266 76,411 Total stock-based compensation expense $ 49,026 $ 50,169 $ 153,372 $ 142,125

NET INCOME (LOSS) PER COMMON _2

NET INCOME (LOSS) PER COMMON SHARE (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per common share (common shares in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Numerator: Net Income (loss), basic $ (36,494) $ 784,803 $ (6,182) $ 837,001 Add: Interest on convertible notes — 7,070 — 18,333 Net Income (loss), diluted $ (36,494) $ 791,873 $ (6,182) $ 855,334 Denominator: Weighted-average common shares outstanding, basic 183,214 181,142 182,616 180,592 Effect of dilutive securities: Options to purchase common stock — 1,731 — 1,728 Common stock issuable under the 2020 notes — 3,983 — 3,983 Common stock issuable under the 2024 notes — 3,970 — 3,970 Common stock issuable under the 2027 notes — 4,365 — 2,373 Unvested RSUs — 1,926 — 1,765 Common stock potentially issuable for ESPP purchases — 346 — 337 The Company’s common stock held by the NQDC — 211 — 211 Weighted-average common shares outstanding, diluted 183,214 197,674 182,616 194,959 Net income (loss) per common share, basic $ (0.20) $ 4.33 $ (0.03) $ 4.63 Net income (loss) per common share, diluted $ (0.20) $ 4.01 $ (0.03) $ 4.39
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 basic and diluted income (loss) per common share as they were anti-dilutive (in thousands): Three Months Ended September 30, Nine Months Ended 2021 2020 2021 2020 Options to purchase common stock 6,649 5,172 6,649 5,175 Common stock issuable under the 2024 Notes 3,970 — 3,970 — Common stock issuable under the 2027 Notes 4,365 — 4,365 — Unvested RSUs 5,292 2,900 5,292 3,060 Common stock potentially issuable for ESPP purchases 582 193 582 204 The Company’s common stock held by the NQDC 197 — 197 — Total number of potentially issuable shares 21,055 8,265 21,055 8,439

Financial Instruments - Schedul

Financial Instruments - Schedule of Cash, Cash Equivalents and Available-for-Sale Securities by Significant Investment Category (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,544,506	$ 1,345,801
Gross Unrealized Gains	1,823	5,069
Gross Unrealized Losses	(235)	(11)
Aggregate Fair Value	1,546,094	1,350,859
Cash and Cash Equivalents	617,143	649,158	[1]
Short-term Marketable Securities	462,333	416,228	[1]
Long-term Marketable Securities	466,618	285,473	[1]
Level 1: | Cash
Schedule of Available-for-sale Securities [Line Items]
Cash	294,209	370,325
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Aggregate Fair Value	294,209	370,325
Cash and Cash Equivalents	294,209	370,325
Short-term Marketable Securities	0	0
Long-term Marketable Securities	0	0
Level 2:
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,250,297	975,476
Gross Unrealized Gains	1,823	5,069
Gross Unrealized Losses	(235)	(11)
Aggregate Fair Value	1,251,885	980,534
Cash and Cash Equivalents	322,934	278,833
Short-term Marketable Securities	462,333	416,228
Long-term Marketable Securities	466,618	285,473
Level 2: | Money market instruments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	291,735	264,833
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Aggregate Fair Value	291,735	264,833
Cash and Cash Equivalents	291,735	264,833
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	560,004	413,137
Gross Unrealized Gains	1,230	3,261
Gross Unrealized Losses	(198)	(8)
Aggregate Fair Value	561,036	416,390
Cash and Cash Equivalents	703	0
Short-term Marketable Securities	177,468	220,551
Long-term Marketable Securities	382,865	195,839
Level 2: | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	210,444	265,298
Gross Unrealized Gains	416	1,555
Gross Unrealized Losses	(7)	(1)
Aggregate Fair Value	210,853	266,852
Cash and Cash Equivalents	12,999	14,000
Short-term Marketable Securities	161,207	192,488
Long-term Marketable Securities	36,647	60,364
Level 2: | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	129,818
Gross Unrealized Gains	1
Gross Unrealized Losses	(1)
Aggregate Fair Value	129,818
Cash and Cash Equivalents	17,497
Short-term Marketable Securities	112,321
Long-term Marketable Securities	0
Level 2: | Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	55,182	31,659
Gross Unrealized Gains	26	85
Gross Unrealized Losses	(23)	(2)
Aggregate Fair Value	55,185	31,742
Cash and Cash Equivalents	0	0
Short-term Marketable Securities	8,272	3,189
Long-term Marketable Securities	46,913	28,553
Level 2: | Foreign and other
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,114	549
Gross Unrealized Gains	150	168
Gross Unrealized Losses	(6)	0
Aggregate Fair Value	3,258	717
Cash and Cash Equivalents	0	0
Short-term Marketable Securities	3,065	0
Long-term Marketable Securities	$ 193	$ 717
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]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Strategic Investment | Fair Value, Measurements, Recurring
Schedule of Available-for-sale Securities [Line Items]
Strategic investments fair value	$ 16.3	$ 10.5

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 75,328	$ 76,673
Work-in-process	412,434	308,286
Finished goods	261,644	313,589
Total inventory	$ 749,406	$ 698,548	[1]
[1]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	[1]
Inventory [Line Items]
Inventory	$ 749,406		$ 749,406		$ 698,548
Depreciation expense, net of amounts capitalized into inventory	11,400	$ 11,100	35,700	$ 31,100
Voxzogo
Inventory [Line Items]
Inventory	$ 4,800		$ 4,800
[1]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

Supplemental Balance Sheet In_5

Supplemental Balance Sheet Information - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Property, plant and equipment, gross	$ 1,724,702	$ 1,668,066
Accumulated depreciation	(699,915)	(635,595)
Property, plant and equipment, net	$ 1,024,787	$ 1,032,471	[1]
[1]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

Supplemental Balance Sheet In_6

Supplemental Balance Sheet Information - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Finite-lived intangible assets	$ 661,781	$ 644,087
Less: Accumulated amortization	(273,294)	(226,816)
Net carrying value	$ 388,487	$ 417,271	[1]
[1]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

Supplemental Balance Sheet In_7

Supplemental Balance Sheet Information - Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts payable and accrued operating expenses	$ 203,321	$ 191,429
Accrued compensation expense	158,130	165,023
Accrued rebates payable	68,329	65,526
Accrued royalties payable	14,512	17,155
Forward foreign currency exchange contracts	5,323	17,798
Lease liabilities	9,659	11,754
Value added taxes payable	1,412	9,562
Accrued income taxes	564	9,661
Other	5,461	4,640
Total accounts payable and accrued liabilities	$ 466,711	$ 492,548	[1]
[1]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Financial Assets and Liabilities (Detail) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
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	$ 0
Liabilities remeasured	0	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	25,356,000	24,449,000
Fair value of financial assets, Total	27,445,000	26,864,000
Fair value of other current liabilities	50,276,000
Fair value of other non-current liabilities	37,725,000	80,092,000
Fair value of financial liabilities, Total	88,001,000	82,507,000
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	2,089,000	2,415,000
Fair value of other non-current liabilities	22,521,000	19,962,000
Fair Value, Measurements, Recurring | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	48,187,000
Fair value of other non-current liabilities	15,204,000	60,130,000
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	25,356,000	24,449,000
Fair value of financial assets, Total	27,445,000	26,864,000
Fair value of other current liabilities	2,089,000
Fair value of other non-current liabilities	22,521,000	19,962,000
Fair value of financial liabilities, Total	24,610,000	22,377,000
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	2,089,000	2,415,000
Fair value of other non-current liabilities	22,521,000	19,962,000
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 current liabilities	0
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 current liabilities	48,187,000
Fair value of other non-current liabilities	15,204,000	60,130,000
Fair value of financial liabilities, Total	63,391,000	60,130,000
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 current liabilities	48,187,000
Fair value of other non-current liabilities	15,204,000	60,130,000
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	2,089,000	2,415,000
Fair value of other non-current assets	22,521,000	19,962,000
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	2,089,000	2,415,000
Fair value of other non-current assets	22,521,000	19,962,000
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	2,835,000	4,487,000
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	2,835,000	4,487,000
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	9 Months Ended
	Sep. 30, 2021USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration as of December 31, 2020	$ 60,130
Changes in the fair value of contingent consideration	6,254
Foreign exchange remeasurement of Euro denominated contingent consideration	(2,993)
Contingent consideration as of September 30, 2021	$ 63,391

Derivative Instruments and He_3

Derivative Instruments and Hedging Strategies - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)
Derivative [Line Items]
Amount reclassified from AOCI to earnings as related to forecasted revenue and operating expense transactions	$ 6.2
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Maturity of derivatives	2 years
Not Designated as Hedging Instrument
Derivative [Line Items]
Maturity of derivatives	3 months

Derivative Instruments and He_4

Derivative Instruments and Hedging Strategies - Summary of Derivatives Designated as and Not Designated as Hedging Instruments Outstanding (Detail) - Foreign exchange contracts - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivatives Designated As Hedging Instruments | Sell
Derivative [Line Items]
Notional amount	$ 654,516	$ 782,327
Derivatives Designated As Hedging Instruments | Purchase
Derivative [Line Items]
Notional amount	168,080	189,540
Not Designated as Hedging Instrument | Sell
Derivative [Line Items]
Notional amount	77,040	98,343
Not Designated as Hedging Instrument | Purchase
Derivative [Line Items]
Notional amount	$ 37,285	$ 12,277

Derivative Instruments and He_5

Derivative Instruments and Hedging Strategies - Fair Value Carrying Amount of Derivatives (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative asset, fair value	$ 16,455	$ 9,500
Derivative liability, fair value	6,809	28,818
Level 2: | Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Derivative asset, fair value	16,203	9,416
Derivative liability, fair value	6,743	28,571
Level 2: | Derivatives Designated As Hedging Instruments | Other current assets
Derivative [Line Items]
Derivative asset, fair value	11,883	6,268
Level 2: | Derivatives Designated As Hedging Instruments | Other assets
Derivative [Line Items]
Derivative asset, fair value	4,320	3,148
Level 2: | Derivatives Designated As Hedging Instruments | Accounts payable and accrued liabilities
Derivative [Line Items]
Derivative liability, fair value	5,257	17,551
Level 2: | Derivatives Designated As Hedging Instruments | Other long-term liabilities
Derivative [Line Items]
Derivative liability, fair value	1,486	11,020
Level 2: | Not Designated as Hedging Instrument | Other current assets
Derivative [Line Items]
Derivative asset, fair value	252	84
Level 2: | Not Designated as Hedging Instrument | Accounts payable and accrued liabilities
Derivative [Line Items]
Derivative liability, fair value	$ 66	$ 247

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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Revenue	$ 408,742	$ 476,784	$ 1,396,465	$ 1,408,338
Operating expenses as reported	461,961	532,725	1,412,926	1,400,263
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) Recognized in Earnings	1,302	4,166	2,310	9,600
Operating expenses as reported | 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	(268)	(815)	81	(4,274)
Net product revenues
Derivative Instruments, Gain (Loss) [Line Items]
Revenue	393,840	460,741	1,348,279	1,368,816
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	$ 401	$ 2,693	$ (5,034)	$ 17,301

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	Sep. 30, 2021	Oct. 31, 2018
Debt Instrument [Line Items]
Carrying value of equity component	$ 1,100,000,000
The 2018 Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 200,000,000
Outstanding amount	$ 0

Debt - Summary of Convertible D

Debt - Summary of Convertible Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Convertible notes	$ 1,100,000
Convertible notes, net of unamortized discount and deferred offering costs	1,078,093	$ 1,075,145	[1]
Total convertible debt, net	1,078,093	1,075,145
Total fair value of fixed rate convertible debt	$ 1,111,812	$ 1,157,804
1.25% Senior Subordinated Convertible Notes Due in May 2027
Debt Instrument [Line Items]
Convertible notes stated rate	1.25%	1.25%
Convertible notes	$ 600,000	$ 600,000
Unamortized discount net of deferred offering costs	(11,478)	(12,995)
Short-term contingent consideration	588,522	587,005
Total fair value of fixed rate convertible debt	$ 600,858	$ 627,090
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
Unamortized discount net of deferred offering costs	(5,429)	(6,860)
Convertible notes, net of unamortized discount and deferred offering costs	489,571	488,140
Total fair value of fixed rate convertible debt	$ 510,954	$ 530,714
[1]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

Debt - Summary of Interest Expe

Debt - Summary of Interest Expense on Convertible Debt (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule Of Interest Expenses [Line Items]
Total interest expense on convertible debt	$ 3,870	$ 9,597	$ 11,491	$ 24,560
Convertible Senior Notes
Schedule Of Interest Expenses [Line Items]
Coupon interest expense	2,617	4,255	7,849	9,443
Accretion of discount on convertible notes	835	4,696	2,503	13,201
Amortization of debt issuance costs	148	535	445	1,565
Total interest expense on convertible debt	$ 3,600	$ 9,486	$ 10,797	$ 24,209

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - 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		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021		Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	[1]	$ 4,241,571	$ 3,236,679	$ 4,106,002	[2]	$ 3,122,381
Other comprehensive income (loss) before      reclassifications		11,128	(18,295)	20,626		3,798
Less: gain (loss) reclassified from AOCI		133	1,878	(4,953)		13,027
Tax effect		183	508	799		(550)
Net current-period other comprehensive income (loss)		11,178	(19,665)	26,378		(9,779)
Ending balance		4,266,149	4,053,893	4,266,149		4,053,893
Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(2,760)	22,963	(20,028)		16,614
Other comprehensive income (loss) before      reclassifications		11,914	(16,094)	24,096		1,404
Less: gain (loss) reclassified from AOCI		133	1,878	(4,953)		13,027
Tax effect		0	0	0		0
Net current-period other comprehensive income (loss)		11,781	(17,972)	29,049		(11,623)
Ending balance		9,021	4,991	9,021		4,991
Unrealized Gains (Losses) on Available for-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		1,821	7,087	3,889		3,565
Other comprehensive income (loss) before      reclassifications		(786)	(2,201)	(3,470)		2,379
Less: gain (loss) reclassified from AOCI		0	0	0		0
Tax effect		183	508	799		(550)
Net current-period other comprehensive income (loss)		(603)	(1,693)	(2,671)		1,829
Ending balance		1,218	5,394	1,218		5,394
Other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		0	0	0		(15)
Other comprehensive income (loss) before      reclassifications		0	0	0		15
Less: gain (loss) reclassified from AOCI		0	0	0		0
Tax effect		0	0	0		0
Net current-period other comprehensive income (loss)		0	0	0		15
Ending balance		0	0	0		0
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	[1]	(939)	30,050	(16,139)		20,164
Ending balance		$ 10,239	$ 10,385	$ 10,239		$ 10,385
[1]	The beginning balances for the nine-month periods were derived from the audited Consolidated Financial Statements included in Company’s Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on February 26, 2021.
[2]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

Revenue, Credit Concentration_3

Revenue, Credit Concentrations and Geographic Information - Additional Information (Detail) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)Segment	Dec. 31, 2020USD ($)
Concentration Risk And Geographic Information [Line Items]
Number of operating business segment | Segment	1
Accounts receivable, net	$ 374,937	$ 448,351	[1]
Customers
Concentration Risk And Geographic Information [Line Items]
Accounts receivable, net	$ 83,900	$ 72,100
Credit Concentration Risk | Accounts Receivable | Customer One
Concentration Risk And Geographic Information [Line Items]
Concentration risk, percentage	31.00%	24.00%
Credit Concentration Risk | Accounts Receivable | Customer Two
Concentration Risk And Geographic Information [Line Items]
Concentration risk, percentage	14.00%	22.00%
[1]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.

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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue from External Customer [Line Items]
Total revenues	$ 408,742	$ 476,784	$ 1,396,465	$ 1,408,338
United States
Revenue from External Customer [Line Items]
Total revenues	196,239	252,948	608,670	729,672
Europe
Revenue from External Customer [Line Items]
Total revenues	115,497	121,158	450,016	375,453
Latin America
Revenue from External Customer [Line Items]
Total revenues	38,958	44,064	140,911	141,852
Rest of world
Revenue from External Customer [Line Items]
Total revenues	$ 58,048	$ 58,614	$ 196,868	$ 161,361

Revenue, Credit Concentration_5

Revenue, Credit Concentrations and Geographic Information - Disaggregates of Net Product Revenues by Product (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue from External Customer [Line Items]
Revenue	$ 408,742	$ 476,784	$ 1,396,465	$ 1,408,338
Vimizim | Marketed by Company
Revenue from External Customer [Line Items]
Revenue	136,744	147,891	466,697	401,789
Naglazyme | Marketed by Company
Revenue from External Customer [Line Items]
Revenue	71,172	76,323	297,321	271,585
Kuvan | Marketed by Company
Revenue from External Customer [Line Items]
Revenue	67,687	123,993	217,257	368,604
Palynziq | Marketed by Company
Revenue from External Customer [Line Items]
Revenue	60,729	46,092	173,702	121,354
Brineura | Marketed by Company
Revenue from External Customer [Line Items]
Revenue	32,984	25,455	90,641	75,223
Voxzogo | Marketed by Company
Revenue from External Customer [Line Items]
Revenue	144	0	144	0
Firdapse | Marketed by Company
Revenue from External Customer [Line Items]
Revenue	0	0	0	1,316
Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Marketed by Company
Revenue from External Customer [Line Items]
Revenue	369,460	419,754	1,245,762	1,239,871
Aldurazyme | Marketed by Genzyme
Revenue from External Customer [Line Items]
Revenue	24,380	40,987	102,517	128,945
Total net product revenues
Revenue from External Customer [Line Items]
Revenue	$ 393,840	$ 460,741	$ 1,348,279	$ 1,368,816

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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 408,742	$ 476,784	$ 1,396,465	$ 1,408,338
United States
Disaggregation of Revenue [Line Items]
Revenue	196,239	252,948	608,670	729,672
Europe
Disaggregation of Revenue [Line Items]
Revenue	115,497	121,158	450,016	375,453
Latin America
Disaggregation of Revenue [Line Items]
Revenue	38,958	44,064	140,911	141,852
Rest of world
Disaggregation of Revenue [Line Items]
Revenue	58,048	58,614	196,868	161,361
Total net product revenues
Disaggregation of Revenue [Line Items]
Revenue	393,840	460,741	1,348,279	1,368,816
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim
Disaggregation of Revenue [Line Items]
Revenue	369,460	419,754	1,245,762	1,239,871
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | United States
Disaggregation of Revenue [Line Items]
Revenue	166,554	203,892	491,028	582,734
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Europe
Disaggregation of Revenue [Line Items]
Revenue	108,568	115,548	424,144	360,718
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Latin America
Disaggregation of Revenue [Line Items]
Revenue	38,958	44,064	140,911	141,852
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, Palynziq, and Vimizim | Rest of world
Disaggregation of Revenue [Line Items]
Revenue	55,380	56,250	189,679	154,567
Marketed by Genzyme | Aldurazyme
Disaggregation of Revenue [Line Items]
Revenue	$ 24,380	$ 40,987	$ 102,517	$ 128,945

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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Customer A, B, & C
Concentration Risk [Line Items]
Concentration risk, percentage	47.00%	41.00%	41.00%	41.00%
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	20.00%	16.00%	17.00%	15.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	16.00%	14.00%	14.00%	14.00%
Customer C
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%	11.00%	10.00%	12.00%

Stock-Based Compensation - Expe

Stock-Based Compensation - Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 49,026	$ 50,169	$ 153,372	$ 142,125
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	4,339	10,342	16,907	20,381
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	17,866	15,705	56,199	45,333
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 26,821	$ 24,122	$ 80,266	$ 76,411

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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net Income (loss), basic	$ (36,494)	$ 784,803	$ (6,182)	$ 837,001
Add: Interest on convertible notes	0	7,070	0	18,333
Net Income (loss), diluted	$ (36,494)	$ 791,873	$ (6,182)	$ 855,334
Denominator:
Weighted average common shares outstanding, basic (in shares)	183,214	181,142	182,616	180,592
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Weighted average common shares outstanding, diluted (in shares)	183,214	197,674	182,616	194,959
Net income (loss) per common share, basic (in dollars per share)	$ (0.20)	$ 4.33	$ (0.03)	$ 4.63
Net income (loss) per common share, diluted (in dollars per share)	$ (0.20)	$ 4.01	$ (0.03)	$ 4.39
Options to purchase common stock
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities (in shares)	0	1,731	0	1,728
Common stock issuable under the 2020 Notes
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities (in shares)	0	3,983	0	3,983
Common stock issuable under the 2024 notes
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities (in shares)	0	3,970	0	3,970
Common stock issuable under the 2027 Notes
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities (in shares)	0	4,365	0	2,373
Unvested RSUs
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities (in shares)	0	1,926	0	1,765
Common stock potentially issuable for ESPP purchases
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities (in shares)	0	346	0	337
The Company’s common stock held by the NQDC
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Effect of dilutive securities (in shares)	0	211	0	211

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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	21,055	8,265	21,055	8,439
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	6,649	5,172	6,649	5,175
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)	3,970	0	3,970	0
Common stock issuable under the 2027 Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	4,365	0	4,365	0
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of potentially issuable shares (in shares)	5,292	2,900	5,292	3,060
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)	582	193	582	204
The Company’s 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)	197	0	197	0

Net Income (Loss) Per Common _5

Net Income (Loss) Per Common Share - Additional Information (Detail) - 1.50% Senior Subordinated Convertible Notes Due in October 2020 - $ / shares	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Line Items]
Convertible notes stated rate	1.50%
Debt instrument, convertible, conversion price, per share (in dollars per share)		$ 94.15

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	[1]
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones	$ 708,800
Contingent liabilities	63,400
Short-term contingent consideration	48,187	$ 0
Purchase commitments and other minimum contractual obligations	107,700
Kuvan And Palynziq | Third Party
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones	70,000
Early Stage Development Program | Third Party
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones	405,500
Programs No Longer Being Developed | Third Party
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones	$ 233,300
[1]	(1) December 31, 2020 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, 2020, filed with the SEC on February 26, 2021.