BioMarin Pharmaceutical (BMRN) 10-K 26 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Feb. 13, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	BMRN
Entity Registrant Name	BIOMARIN PHARMACEUTICAL INC
Entity Central Index Key	1,048,477
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		176,072,261
Entity Public Float			$ 8.5

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 598,028	$ 408,330
Short-term investments	797,940	381,347
Accounts receivable, net	261,365	215,280
Inventory	475,775	355,126
Other current assets	74,036	61,708
Total current assets	2,207,144	1,421,791
Noncurrent assets:
Long-term investments	385,785	572,711
Property, plant and equipment, net	896,700	798,768
Intangible assets, net	517,510	553,780
Goodwill	197,039	197,039
Deferred tax assets	399,095	446,786
Other assets	29,852	32,815
Total assets	4,633,125	4,023,690
Current liabilities:
Accounts payable and accrued liabilities	401,921	370,505
Short-term convertible debt, net	360,949	22,478
Short-term contingent acquisition consideration payable	53,648	46,327
Total current liabilities	816,518	439,310
Noncurrent liabilities:
Long-term convertible debt, net	813,521	660,761
Long-term contingent acquisition consideration payable	135,318	115,310
Other long-term liabilities	59,105	42,034
Total liabilities	1,824,462	1,257,415
Stockholders’ equity:
Common stock, $0.001 par value: 500,000,000 and 250,000,000 shares authorized, respectively; 175,843,749 and 172,647,588 shares issued and outstanding, respectively.	176	173
Additional paid-in capital	4,483,220	4,288,113
Company common stock held by Nonqualified Deferred Compensation Plan (the NQDC)	(14,224)	(14,321)
Accumulated other comprehensive income (loss)	(22,961)	12,816
Accumulated deficit	(1,637,548)	(1,520,506)
Total stockholders’ equity	2,808,663	2,766,275
Total liabilities and stockholders’ equity	$ 4,633,125	$ 4,023,690

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	250,000,000
Common stock, shares issued	175,843,749	172,647,588
Common stock, shares outstanding	175,843,749	172,647,588

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
REVENUES:
Net product revenues	$ 1,270,445	$ 1,110,381	$ 884,522
Royalty and other revenues	43,201	6,473	5,373
Total revenues	1,313,646	1,116,854	889,895
OPERATING EXPENSES:
Cost of sales	241,786	209,620	152,008
Research and development	610,753	661,905	634,806
Selling, general and administrative	554,336	476,593	402,271
Intangible asset amortization and contingent consideration	46,471	(26,953)	(17,690)
Impairment of intangible assets	0	599,118	198,700
Gain on sale of intangible asset	(125,000)	0	(369,498)
Total operating expenses	1,328,346	1,920,283	1,000,597
LOSS FROM OPERATIONS	(14,700)	(803,429)	(110,702)
Equity in the loss of BioMarin/Genzyme LLC	(1,291)	(538)	(817)
Interest income	14,853	7,487	4,501
Interest expense	(42,707)	(39,499)	(38,244)
Other income (expense)	7,970	4,929	(9,462)
LOSS BEFORE INCOME TAXES	(35,875)	(831,050)	(154,724)
Provision for (benefit from) income taxes	81,167	(200,840)	17,075
NET LOSS	$ (117,042)	$ (630,210)	$ (171,799)
NET LOSS PER SHARE, BASIC	$ (0.67)	$ (3.80)	$ (1.07)
NET LOSS PER SHARE, DILUTED	$ (0.67)	$ (3.81)	$ (1.07)
Weighted average common shares outstanding, basic	174,427	165,985	160,025
Weighted average common shares outstanding, diluted	174,427	166,219	160,025

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
NET LOSS	$ (117,042)	$ (630,210)	$ (171,799)
OTHER COMPREHENSIVE INCOME (LOSS):
Net foreign currency gain (loss)	5	(2)	(59)
Unrealized holding loss arising during the period, net of tax impact of $272, $4,412 and $1,581, respectively.	(483)	(7,692)	(2,878)
Less: reclassifications to net loss, net of tax impact of $(1,191), $42 and $(681), respectively.	2,061	(73)	1,192
Net change in unrealized holding loss, net of tax	(2,544)	(7,619)	(4,070)
Unrealized holding gain (loss) arising during the period, net of tax impact of $0.	(38,351)	9,677	17,300
Less: reclassifications to net loss, net of tax impact of $0.	(5,113)	10,273	19,604
Net change in unrealized holding loss, net of tax	(33,238)	(596)	(2,304)
OTHER COMPREHENSIVE LOSS, NET OF TAX	(35,777)	(8,217)	(6,433)
COMPREHENSIVE LOSS	$ (152,819)	$ (638,427)	$ (178,232)

CONSOLIDATED STATEMENTS OF COM6

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Unrealized holding loss arising during the period, tax	$ 272	$ 4,412	$ 1,581
Reclassifications to net loss, tax	(1,191)	42	(681)
Unrealized holding gain (loss) arising during the period, tax	0	0	0
Reclassifications to net loss, tax	$ 0	$ 0	$ 0

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Company Stock Held By NQDC	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2014	$ 1,527,894	$ 149	$ 2,359,744	$ (9,695)	$ 27,466	$ (849,770)
Beginning Balance (in shares) at Dec. 31, 2014		149,094
Net loss	(171,799)					(171,799)
Other comprehensive loss	(6,433)				(6,433)
Issuance of common stock, net of offering costs	888,257	$ 10	888,247
Issuance of common stock, net of offering costs (in shares)		9,775
Issuances under equity incentive plans, net of tax	40,056	$ 2	40,054
Issuances under equity incentive plans, net of tax (in share)		2,208
Conversion of convertible notes, net	9,112	$ 1	9,111
Conversion of convertible notes, net (in shares)		449
Company stock held by NQDC	(3,921)			(3,921)
Excess tax benefit from stock option exercises	2,190		2,190
Stock-based compensation	115,491		115,491
Ending Balance at Dec. 31, 2015	2,400,847	$ 162	3,414,837	(13,616)	21,033	(1,021,569)
Ending Balance (in shares) at Dec. 31, 2015		161,526
Net loss	(630,210)					(630,210)
Cumulative-effect adjustment of new share-based compensation guidance	131,273					131,273
Other comprehensive loss	(8,217)				(8,217)
Issuance of common stock, net of offering costs	712,938	$ 8	712,930
Issuance of common stock, net of offering costs (in shares)		7,500
Issuances under equity incentive plans, net of tax	14,758	$ 3	14,755
Issuances under equity incentive plans, net of tax (in share)		3,184
Conversion of convertible notes, net	8,928		8,928
Conversion of convertible notes, net (in shares)		438
Company stock held by NQDC	(705)			(705)
Stock-based compensation	136,663		136,663
Ending Balance at Dec. 31, 2016	2,766,275	$ 173	4,288,113	(14,321)	12,816	(1,520,506)
Ending Balance (in shares) at Dec. 31, 2016		172,648
Net loss	(117,042)					(117,042)
Other comprehensive loss	(35,777)				(35,777)
Issuances under equity incentive plans, net of tax	27,352	$ 2	27,350
Issuances under equity incentive plans, net of tax (in share)		2,092
Conversion of convertible notes, net	22,477	$ 1	22,476
Conversion of convertible notes, net (in shares)		1,104
Company stock held by NQDC	97			97
Stock-based compensation	145,281		145,281
Ending Balance at Dec. 31, 2017	$ 2,808,663	$ 176	$ 4,483,220	$ (14,224)	$ (22,961)	$ (1,637,548)
Ending Balance (in shares) at Dec. 31, 2017		175,844

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (117,042)	$ (630,210)	$ (171,799)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	87,861	96,912	47,187
Non-cash interest expense	32,300	29,930	28,493
Accretion of discount on investments	3,077	1,300	2,177
Stock-based compensation expense	140,263	134,641	111,525
Gain on sale of intangible asset	(125,000)	0	(369,498)
(Gain) loss on sale of equity investment	(3,252)	108	(3,022)
Impairment of assets	0	599,118	211,502
Deferred income taxes	44,464	(228,054)	(76,827)
Unrealized foreign exchange loss (gain)	6,258	(14,481)	(19,575)
Non-cash changes in the fair value of contingent acquisition consideration payable	10,342	(57,161)	(28,457)
Other	5,935	336	2,463
Changes in operating assets and liabilities:
Accounts receivable, net	(25,256)	(51,483)	(16,367)
Inventory	(96,890)	(64,512)	(50,989)
Other current assets	(20,687)	19,316	25,800
Other assets	(2,439)	(4,979)	(3,157)
Accounts payable and accrued liabilities	45,517	(53,205)	90,298
Other long-term liabilities	5,792	(5,413)	747
Net cash used in operating activities	(8,757)	(227,837)	(219,499)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant and equipment	(199,219)	(148,380)	(227,653)
Deposit on purchase of PKU rights	0	0	(371,756)
Maturities and sales of investments	425,960	367,569	424,713
Purchase of available-for-sale debt securities	(655,447)	(699,749)	(873,184)
Proceeds from sale of intangible asset	125,000	0	410,000
Business acquisitions, net of cash acquired	0	(2,789)	(538,392)
Other	(1,753)	(698)	(3,326)
Net cash used in investing activities	(305,459)	(484,047)	(1,179,598)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercises of awards under equity incentive plans	60,859	74,227	63,045
Taxes paid related to net share settlement of equity awards	(33,507)	(59,469)	(22,989)
Proceeds from public offering of common stock, net	0	712,938	888,257
Proceeds from convertible senior subordinated note offering, net	481,713	0	0
Payment of contingent acquisition consideration payable	(1,894)	0	0
Other	(26)	(588)	(2,590)
Net cash provided by financing activities	507,145	727,108	925,723
Effect of exchange rate changes on cash	(3,231)	(3,934)	(5,072)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	189,698	11,290	(478,446)
Cash and cash equivalents:
Beginning of period	408,330	397,040	875,486
End of period	598,028	408,330	397,040
SUPPLEMENTAL CASH FLOW DISCLOSURES:
Cash paid for interest, net of interest capitalized into fixed assets	8,544	8,643	9,307
Cash paid for income taxes	23,895	95,857	16,084
Stock-based compensation capitalized into inventory	16,052	11,449	11,140
Depreciation capitalized into inventory	24,076	17,375	14,627
SUPPLEMENTAL CASH FLOW DISCLOSURES FOR NON-CASH INVESTING AND FINANCING ACTIVITIES:
Increase (decrease) in accounts payable and accrued liabilities related to fixed assets	(25,786)	20,158	(4,651)
Conversion of convertible debt, net	$ 22,477	$ 8,928	$ 9,112

NATURE OF OPERATIONS AND BUSINE

NATURE OF OPERATIONS AND BUSINESS RISKS	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
NATURE OF OPERATIONS AND BUSINESS RISKS	(1) NATURE OF OPERATIONS AND BUSINESS RISKS BioMarin Pharmaceutical Inc. (the Company or BioMarin) 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 therapy portfolio consists of six commercial products and multiple clinical and pre-clinical product candidates. The Company expects to continue to finance future cash needs that exceed its operating activities primarily through its current cash, cash equivalents and investments and through proceeds from debt or equity offerings, commercial borrowing, or through collaborative agreements with corporate partners. If the Company elects to increase its spending on development programs significantly above current long-term plans or enters into potential licenses and other acquisitions of complementary technologies, products or companies, the Company may need additional capital. The Company is subject to a number of risks, including: the financial performance of its commercial products; the potential need for additional financings; the Company’s ability to successfully commercialize its approved products; the uncertainty of the Company’s research and development (R&D) efforts resulting in future successful commercial products; the Company’s ability to successfully obtain regulatory approval for new products; significant competition from larger organizations; reliance on the proprietary technology of others; dependence on key personnel; uncertain patent protection; dependence on corporate partners and collaborators; and possible restrictions on reimbursement from governmental agencies and healthcare organizations, as well as other changes in the healthcare industry. Please see “ Risk Factors

BASIS OF PRESENTATION

BASIS OF PRESENTATION	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
BASIS OF PRESENTATION	(2) BASIS OF PRESENTATION Basis of Presentation These 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 for Annual Reports on Form 10-K and include the accounts of BioMarin and its wholly owned subsidiaries. All significant intercompany transactions have been eliminated. Management performed an evaluation of the Company’s activities through the date of filing of this Annual Report on Form 10-K, and has concluded that there are no subsequent events or transactions that occurred subsequent to the balance sheet date and prior to the filing this Annual Report on Form 10-K that would require recognition or disclosure in the Consolidated Financial Statements. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the dates of the financial statements, and the reported amounts of revenues and expenses during the reporting period. 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.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	(3) SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Cash, Cash Equivalents and Investments The Company treats liquid investments with original maturities of three months or less when purchased as cash and cash equivalents. Cash and cash equivalents primarily consist of cash on deposit with banks, investments in money market funds and debt securities with original maturities of three months or less when purchased. The Company determines the appropriate classification of its investments in debt and equity securities at the time of purchase and reevaluates such designations at each balance sheet date. The Company classifies its debt and equity securities with original maturities greater than three months when purchased as either short-term or long-term investments based on each instrument’s underlying contractual maturity date and its availability for use in current operations. Available-for-sale debt securities are recorded at fair market value, with unrealized gains and losses included in Accumulated Other Comprehensive Income (Loss) on the Company’s Consolidated Balance Sheets, with the exception of unrealized losses believed to be other-than-temporary, if any, which are reported in Other Income (Expense) in the current period. Available-for-sale debt securities primarily consist of corporate securities, commercial paper, U.S. federal government agency securities and certificates of deposit. Inventory The Company values inventory at the lower of cost and net realizable value and determines the cost of inventory using the average-cost method. The Company analyzes its inventory levels quarterly and adjusts inventory to its net realizable value, if required, for obsolete, or has a cost basis in excess of its expected net realizable value or for quantities in excess of expected requirements. These adjustments are recognized as Cost of Sales in the Company’s Consolidated Statements of Operations. When future commercialization is considered probable and the future economic benefit is expected to be realized, based on management’s judgment, the Company capitalizes pre-launch inventory costs prior to regulatory approval. A number of factors are taken into consideration, including the current status in the regulatory approval process, pivotal clinical trial results for the underlying product candidate, results from meetings with the relevant regulatory authorities prior to the filing of regulatory applications, historical experience, as well as potential impediments to the approval process such as product safety or efficacy, commercialization and marketplace trends. As of December 31, 2017, the amount of pre-launch inventory on the Company’s Consolidated Balance Sheets was not significant. Property, Plant and Equipment Property, plant and equipment are stated at cost net of accumulated depreciation. Depreciation is computed using the straight-line method over the related estimated useful lives as presented in the table below. Significant additions and improvements are capitalized, while repairs and maintenance are charged to expense as incurred. Depreciation of property, plant and equipment are included in Cost of Sales, Selling, General and Administrative and Research and Development, as appropriate, in the Consolidated Statements of Operations. Property and equipment purchased for specific R&D projects with no alternative uses are expensed as incurred and recorded to Research and Development in the Consolidated Statements of Operations. Leasehold improvements Shorter of life of asset or lease term Building and improvements 15 to 50 years Manufacturing and laboratory equipment 5 to 18 years Computer hardware and software 3 to 10 years Office furniture and equipment 5 to 10 years Vehicles 5 years Land improvements 5 to 10 years Land Not applicable Construction-in-progress Not applicable Leases Certain of the Company’s operating lease agreements include scheduled rent escalations over the lease term, as well as tenant improvement allowances. Scheduled increases in rent expense are recognized on a straight-line basis over the lease term. The difference between rent expense and rent paid is recorded as deferred rent and included in Other Liabilities in the Consolidated Balance Sheets. The tenant improvement allowances and free rent periods are recognized as a reduction of rent expense over the lease term on a straight-line basis. Rent expense is recorded to Cost of Sales, Research and Development and/or Selling, General and Administrative, as appropriate, in the Consolidated Statements of Operations. Goodwill and Intangible Assets The Company records goodwill in a business combination when the total consideration exceeds the fair value of the net tangible and identifiable intangible assets acquired. Intangible assets with indefinite useful lives are related to purchased in-process research and development (IPR&D) projects and are measured at their respective fair values as of the acquisition date. The Company does not amortize goodwill and intangible assets with indefinite useful lives. Intangible assets related to IPR&D projects are considered to be indefinite lived until the completion or abandonment of the associated R&D efforts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets are considered finite-lived and are amortized using the straight-line method based on their respective estimated useful lives at that point in time. The amortization of these intangible assets is included in Intangible Asset Amortization and Contingent Consideration in the Consolidated Statements of Operations. Impairment The Company reviews its goodwill and indefinite lived intangible assets for impairment annually in the fourth quarter, or more frequently as warranted by events or changes in circumstances which indicate that the carrying amount may not be recoverable. The Company qualitatively assesses goodwill and indefinite lived intangible assets to determine whether it is more likely than not that the fair value of the Company’s single reporting unit or other indefinite lived intangible asset is less than its carrying amount. If it is determined that the fair value is more likely than not less than its carrying value, a two-step impairment test will be performed. In the first step of the impairment test, the Company compares the carrying value of its single reporting unit or applicable asset to its fair value, which the Company estimates using a discounted cash flow analysis. If the carrying amount of its single reporting unit or asset exceeds its estimated fair value, the Company performs the second step, and determines the impairment loss, if any, as the excess of the carrying value of the goodwill or intangible asset over its fair value. Impairment charges that are not material are recorded to Intangible Asset Amortization and Contingent Consideration in the Consolidated Statements of Operations. See Note 7 to these Consolidated Financial Statements for the results of the Company’s 2017 qualitative assessment. Long-lived assets including property, plant and equipment and finite-lived intangible assets are reviewed for impairment whenever facts or circumstances whether internally or externally may suggest that the carrying value of an asset or asset group may not be recoverable. Should there be an indication of impairment, the Company tests for recoverability by comparing the estimated undiscounted future cash flows expected to result from the use of the asset or asset group and its eventual disposition to the carrying amount of the asset or asset group. Any excess of the carrying value of the asset or asset group over its estimated fair value is recognized as an impairment loss. Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred, the price to the buyer is fixed or determinable and collection from the customer is reasonably assured. Net Product Revenues —The Company recognizes revenues from product sales when title and risk of loss have passed to the customer, which typically occurs upon delivery. Product sales transactions are evidenced by customer purchase orders, customer contracts, invoices and/or the related shipping documents. Amounts collected from customers and remitted to governmental authorities, which primarily consists of value-added taxes related to product sales in foreign jurisdictions, are presented on a net basis in the Consolidated Statements of Operations, in that taxes billed to customers are not included as a component of net product revenues. In the U.S., the Company’s commercial products are generally sold to specialty pharmacies or end-users, such as hospitals, which act as retailers. Through December 31, 2015, the Company also sold Kuvan to Ares Trading S.A. (Merck Serono) at a price near its manufacturing cost, and Merck Serono resold the product to end users outside the U.S., Canada and Japan. The royalty earned from Kuvan product sold by Merck Serono in the EU was included as a component of Net Product Revenues in the period earned. Outside the U.S., the Company’s commercial products are sold to its authorized distributors or directly to government purchasers or hospitals, which act as the end-users. The Company receives a payment ranging from . See Note 4 to these Consolidated Financial Statements for further discussion on the Company’s adoption of Accounting Standards Update (ASU) No. 2014-09 (ASU 2014-09), Revenue from Contracts with Customers , as amended (commonly referred to as ASC Topic 606) on January 1, 2018. The Company records an allowance for government and other rebates is estimated based on products sold, customer mix, and program requirements. The Company evaluates its customer mix to estimate which sales will be subject to rebates and consider changes to government program guidelines that would impact the actual rebates and/or estimates of which sales qualify for such rebates. The Company updates its estimates and assumptions on a quarterly basis based on actual historical experience and records any necessary adjustments to its reserves. The Company records fees paid to distributors and cash discounts as a reduction of revenue. The Company records allowances for product returns, if appropriate, as a reduction of revenue at the time product sales are recorded. The Company relies on historical return rates to estimate returns. Several factors are considered in determining whether an allowance for product returns is required, including market exclusivity of the products based on their orphan drug status, the patient population, the customers’ limited return rights and the Company’s experience with returns. Because of the pricing of the Company’s commercial products, the limited number of patients and the customers’ limited return rights, most customers and retailers carry a limited inventory. Certain international customers, usually government entities, tend to purchase larger quantities of product less frequently. Although such buying patterns may result in revenue fluctuations from quarter to quarter, the Company has not experienced any increased product returns or risk of product returns related to such buying patterns. Genzyme’s contractual return rights for Aldurazyme are limited to defective product. Based on these factors and the fact that the Company has not experienced significant product returns to date, management has concluded that product returns will be minimal. In the future, if any of these factors and/or the history of product returns change, an allowance for product returns may be required. Royalty and Other Revenues— includes royalties on net sales of products with which the Company has no direct involvement, collaborative agreement revenues and rental income. Royalty revenue Revenue from non-refundable up-front license fees, such as under an obligation to supply product, is recognized as performance occurs and the Company’s obligations are completed or recognized up-front upon agreement execution if there are no continuing involvement performance obligations. Revenue associated with substantive at-risk milestones is recognized based upon the achievement of the milestones set forth in the respective agreements. Advance payments received in excess of amounts earned are classified as deferred revenue on the Company’s Consolidated Balance Sheets . Research and Development R&D costs are generally expensed as incurred. These expenses include contract R&D provided by third parties, most product manufacturing prior to regulatory approval, materials and supplies, clinical and regulatory costs, and personnel costs including salaries, benefits and stock-based compensation. In instances where the Company enters into agreements with third parties for R&D activities, costs are expensed upon the earlier of when non-refundable amounts are due or as services are performed unless there is an alternative future use of the funds in other R&D projects. Amounts due under such arrangements may be either fixed fee or fee for service and may include upfront payments, monthly payments and payments upon the completion of milestones or receipt of deliverables. Convertible Debt For non-conventional convertible debt that may be settled entirely or partially in cash, the Company separately accounts for the liability and equity components by allocating the proceeds from issuance between the liability component and the embedded conversion option, or equity component. The value of the equity component is calculated by first measuring the fair value of the liability component, using the interest rate of a similar liability that does not have a conversion feature, as of the issuance date. The difference between the proceeds from the convertible debt issuance and the amount measured as the liability component is recorded as the equity component with a corresponding discount recorded on the debt. The liability component is presented net of any discounts and issuance costs. For conventional convertible debt that may only be settled with common shares, the Company accounts for the debt net of any discounts or issuance costs on the Consolidated Balance Sheet. The Company recognizes discount accretion and debt issuance cost amortization using the effective interest method as part of Interest Expense in the Consolidated Statements of Operations. Net Loss Per Common Share Basic net loss per share is calculated by dividing net loss by the weighted average shares of common stock outstanding during the period. Diluted net loss per share reflects the potential dilution that would occur if securities or other contracts to issue common stock were exercised or converted into common stock; however, potential common equivalent shares are excluded if their effect is anti-dilutive. See Note 14 to these Consolidated Financial Statements for further details. Stock-Based Compensation The Company has stock-based compensation plans, including an Employee Stock Purchase Plan (ESPP), under which various types of equity-based awards are granted or available to employees, including restricted stock units (RSUs) with both performance and service-based vesting conditions and stock options. Stock-based compensation expense is recognized on a straight-line basis over the requisite service period for each award and is classified as Cost of Sales, Research and Development or Selling, General and Administrative, as appropriate, in the Consolidated Statements of Operations. The Company accounts for forfeitures as they occur. The fair value of each stock option award and the Company’s ESPP awards are estimated on the date of grant using the Black-Scholes valuation model and the following assumptions: expected life of a stock option, expected volatility, risk-free interest rate and expected dividend yield. The dividend yield reflects that the Company has not paid any cash dividends since inception and does not intend to pay any cash dividends in the foreseeable future. The expected life of stock options is based on observed historical exercise patterns. Groups of employees that have similar historical exercise patterns were considered separately for valuation purposes. The Company has identified two groups, executive and non-executive employees, with distinctly different exercise patterns. The executive employee group has a history of holding stock options for longer periods than non-executive employees. The determination of the fair value of stock-based payment awards using an option-pricing model is affected by the Company’s stock price and may use assumptions regarding a number of complex and subjective variables. The fair value of RSUs with service-based vesting conditions and RSUs with performance conditions is determined to be the fair market value of the Company’s underlying common stock on the date of grant. The stock-based compensation for RSUs with service-based vesting is recognized ratably over the period during which the vesting restrictions lapse. Stock-based compensation for RSUs with performance conditions is recognized ratably over the service period beginning in the period the Company determines it is probable that the performance condition will be achieved. See Note 17 to these Consolidated Financial Statements for further information. Income Taxes The Company calculates and provides for income taxes in each of the tax jurisdictions in which it operates. Deferred tax assets and liabilities, measured using enacted tax rates, are recognized for the future tax consequences of temporary differences between the tax and financial statement basis of assets and liabilities. A valuation allowance reduces the deferred tax assets to the amount that is more likely than not to be realized. The Company establishes liabilities or reduces assets for uncertain tax positions when the Company believes certain tax positions are not more likely than not of being sustained if challenged. Each quarter, the Company evaluates these uncertain tax positions and adjusts the related tax assets and liabilities in light of changing facts and circumstances. The Company uses financial projections to support its net deferred tax assets, which contain significant assumptions and estimates of future operations. If such assumptions were to differ significantly, it may have a material impact on the Company’s ability to realize its deferred tax assets. At the end of each period, the Company will reassess the ability to realize its deferred tax benefits. If it is more likely than not that the Company would not realize the deferred tax benefits, a valuation allowance may need to be established against all or a portion of the deferred tax assets, which will result in a charge to tax expense. Foreign Currency For the Company and its subsidiaries, the functional currency has been determined to be the U.S. dollar. Assets and liabilities denominated in foreign currency are remeasured at period-end exchange rates for monetary assets. Non-monetary assets and liabilities denominated in foreign currencies are remeasured at historical rates. Foreign currency transaction gains and losses resulting from remeasurement are recognized in Selling, General and Administrative in the Consolidated Statements of Operations. Derivatives and Hedging Activities The Company accounts for its derivative instruments as either assets or liabilities on the balance sheet and measures them at fair value. Derivatives that are not designated as hedging instruments are adjusted to fair value through earnings in Selling, General and Administrative in the Consolidated Statements of Operations. For derivative instruments that hedge the exposure to variability in expected future cash flows that are designated as cash flow hedges, the effective portion of the gain or loss is reported as a component of Accumulated Other Comprehensive Income (Loss) in shareholders’ equity and reclassified to earnings in the same period or periods during which the hedged transaction affects earnings. The ineffective portion of the gain or loss on the derivative instrument, if any, is recognized in earnings in the current period. To receive hedge accounting treatment, cash flow hedges must be highly effective in offsetting changes to expected future cash flows on hedged transactions. The Company does not hold or issue derivative instruments for trading or speculative purposes. See Note 11 to these Consolidated Financial Statements for further information. Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and non-financials assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. The Company defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities that are required to be recorded at fair value, the Company considers the principal or most advantageous market in which the Company would transact and the market-based risk measurements or assumptions that that market participants would use to price the asset or liability, such as risks inherent in valuation techniques, transfer restrictions and credit risk. When estimating fair value, depending on the nature and complexity of the asset or liability, the Company may use the following techniques: • Income approach, which is based on the present value of a future stream of net cash flows • Market approach, which is based on market prices and other information from market transactions involving identical or comparable assets or liabilities. The Company’s fair value methodologies depend on the following types of inputs: • Quoted prices for identical assets or liabilities in active markets (Level 1 inputs) • Quoted prices for similar assets or liabilities in active markets, or quoted prices for identical or similar assets or liabilities that are not active, or inputs other than quoted process that are directly or indirectly observable, or inputs that are derived principally from, or corroborated by, observable market data by correlation or other means (Level 2 inputs) • Unobservable inputs that reflect estimates and assumptions (Level 3 inputs) See Note 12 to these Consolidated Financial Statements for further information. Segment Information The Company currently operates in one business segment focused on the development and commercialization of innovative therapies for people with serious and life threatening rare diseases and medical conditions. A single management team reports to the chief operating decision maker who comprehensively manages the entire business. All products are included in one segment because the majority of the Company’s products have similar economic and other characteristics, including the nature of the products and production processes, type of customers, distribution methods and regulatory environment. The Company is not organized by market and is managed and operated as one business. The Company does not operate any separate lines of business or separate business entities with respect to its products. Accordingly, the Company does not accumulate discrete financial information with respect to separate products, other than revenues, and does not have separately reportable segments. Acquisitions Acquisitions of businesses are accounted for using the acquisition method of accounting. The Company allocates the purchase price of acquired businesses to the tangible and intangible assets acquired and liabilities assumed based upon their estimated fair values on the acquisition date. The purchase price allocation process requires management to make significant estimates and assumptions, especially at the acquisition date with respect to intangible assets and IPR&D. In connection with the purchase price allocations for acquisitions, the Company estimates the fair value of contingent acquisition consideration payments utilizing a probability-based income approach inclusive of an estimated discount rate. Each reporting period thereafter, the Company revalues these obligations and records increases or decreases in their fair value as adjustments to Intangible Asset Amortization and Contingent Consideration in the Consolidated Statements of Operations. Changes in the fair value of the contingent acquisition consideration payable can result from changes to one or multiple inputs including the estimated probability with respect to regulatory approval, changes in the assumed timing of when milestones are likely to be achieved and changes in assumed discount periods and rates.

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	12 Months Ended
	Dec. 31, 2017
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	(4) RECENT ACCOUNTING PRONOUNCEMENTS Accounting Pronouncements Not Yet Adopted Effective January, 1, 2018, the Company will adopt Accounting Standards Codification, Topic 606, Revenue from Contracts with Customers As the Company completes its analysis of the accounting for the Company’s customer contracts under the new revenue standard, management is assessing the required changes to the Company’s accounting policies, systems and internal control over financial reporting. Based on management’s preliminary assessment of the Company’s material contracts with customers, management does not anticipate that ASC Topic 606 will have a material impact on the timing of revenue recognition for the products that are marketed by the Company. Based on management’s preliminary assessment of the Company’s contract with Genzyme, the Company expects to recognize Aldurazyme revenues when the product is shipped to Genzyme and all the required quality control certifications are complete, because all of the Company’s performance obligations are fulfilled at that point in time. The Company expects to record Aldurazyme net product revenues based on the estimated tiered payment that will be in effect when the product is sold through by Genzyme. Management believes any differences between estimated revenues from Genzyme and actual payments will be insignificant. In the first quarter of 2018, the management expects the impact of adopting ASC Topic 606 to result in a $20.0 million reduction in Accumulated Deficit, the cumulative effect adjustment under the modified retrospective approach, a $26.0 million increase in Accounts Receivable and a $6.0 million decrease in Deferred Tax Assets. In February 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-02, Leases As of December 31, 2017, the Company’s task force formed in connection with the adoption of ASU 2016-02 was in the process of analyzing the Company’s lease contracts and the potential impact the standard may have on its Consolidated Financial Statements and related disclosures. After completing the analysis of the accounting for the Company’s lease contracts under the standard, management will assess the required changes to the Company’s accounting policies, systems and internal control over financial reporting. Based on management’s preliminary analysis, the Company anticipates the standard may have a material impact on the Company’s Consolidated Balance Sheets due to the requirement to recognize lease ROU assets and corresponding liabilities related to leases on the Company’s Consolidated Balance Sheets, but it is not anticipated to have a material impact on the Company’s other Consolidated Financial Statements. See Note 23 to these Consolidated Financial Statements for additional information regarding the Company’s lease obligations as of December 31, 2017. In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . Accounting Pronouncements Adopted In January 2017, the FASB issued ASU No. 2017-04, Goodwill and Other - Simplifying the Test for Goodwill Impairment In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
ACQUISITIONS	(5) ACQUISITIONS The Merck PKU Business On October 1, 2015, the Company entered into a Termination and Transition Agreement with Ares Trading S.A. (Merck Serono), as amended and restated on December 23, 2015 (the A&R Kuvan Agreement), to terminate the Development, License and Commercialization Agreement, dated May 13, 2005, as amended (the License Agreement), between the Company and Merck Serono, including the license to Kuvan the Company had granted to Merck Serono under the License Agreement. Also on October 1, 2015, the Company and Merck Serono entered into a Termination Agreement (the Pegvaliase Agreement) to terminate the license to pegvaliase the Company had granted to Merck Serono under the License Agreement. On January 1, 2016, pursuant to the A&R Kuvan Agreement and the Pegvaliase Agreement, the Company completed the acquisition from Merck Serono and its affiliates of certain rights and other assets with respect to Kuvan and pegvaliase (the Merck PKU Business). As a result, the Company acquired all global rights to Kuvan and pegvaliase from Merck Serono, with the exception of Kuvan in Japan. Previously, the Company had exclusive rights to Kuvan in the U.S. and Canada and pegvaliase in the U.S. and Japan. In connection with the acquisition of the , the Company recognized transaction costs of $0.6 million, of which $0.3 million was recognized in each of the years ended December 31, 2016 and 2015. Pursuant to the A&R Kuvan Agreement, the Company paid Merck Serono $374.5 million in cash and is obligated to pay Merck Serono up to a maximum of €60.0 million, in cash, if future sales milestones are met. Pursuant to the Pegvaliase Agreement, the Company is obligated to pay Merck Serono up to a maximum of €125.0 million, in cash, if future development milestones are met. Merck Serono transferred certain inventory, regulatory materials and approvals, and intellectual property rights to the Company and performed certain transition services for the Company. As of December 31, 2016, the inventory acquired from Merck Serono has been sold through to customers. The Company and Merck Serono have no further rights or obligations under the License Agreement with respect to Kuvan or pegvaliase. Kuvan is a commercialized product for the treatment of patients with phenylketonuria (PKU) and/or for primary BH4 deficiency in certain countries. At the time of the acquisition, pegvaliase was in pivotal studies as a potential therapeutic option for adult patients with PKU. In March 2016, the Company announced that its pivotal Phase 3 PRISM-2 study of pegvaliase met the primary endpoint of change in blood Phe compared with placebo (p<0.0001). The Company submitted a marketing application for pegvaliase in the U.S. in June 2017. The Company plans to submit a Marketing Authorization Application for pegvaliase to the European Medicines Agency (EMA) in the first quarter of 2018. In a notice received from the U.S. Food and Drug Administration (FDA), the Prescription Drug User Fee Act (PDUFA) target action date for pegvaliase has been extended by three months to May 28, 2018, which was changed to May 25, 2018 due to the Memorial Day holiday. Kuvan has Orphan Drug exclusivity in the EU until 2020, and pegvaliase has Orphan Drug designation in the U.S. and the EU. The acquisition date fair value of the contingent acquisition consideration payments, Kuvan global marketing rights, with the exception of Japan, and pegvaliase IPR&D acquired was estimated by applying a probability-based income approach utilizing an appropriate discount rate. See Note 12 to these Consolidated Financial Statements for additional discussion regarding fair value measurements of the contingent acquisition consideration payable included on the Company’s Consolidated Balance Sheet. The following table presents the final allocation of the purchase consideration for the Merck PKU Business acquisition, including the contingent acquisition consideration payable based on the acquisition date fair value. The allocation of the purchase price below reflects an inventory adjustment in the second quarter of 2016. Cash payments $ 374,545 Estimated fair value of contingent acquisition consideration payable 138,974 Total consideration $ 513,519 Kuvan intangible assets $ 172,961 Pegvaliase IPR&D 326,359 Inventory 14,199 Total identifiable assets acquired $ 513,519 The amount allocated to the Kuvan intangible assets is considered to be finite-lived and is being amortized on a straight-line basis over its estimated useful life through 2024. The amount allocated to pegvaliase acquired IPR&D is considered to be indefinite-lived as R&D efforts are ongoing and, as such, is not subject to amortization. See Note 7 to these Consolidated Financial Statements for further discussion of indefinite-lived intangible assets .

INVESTMENTS

INVESTMENTS	12 Months Ended
	Dec. 31, 2017
Investments Schedule [Abstract]
INVESTMENTS	(6) INVESTMENTS The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s available-for-sale debt securities by major security type at December 31, 2017 and 2016 are summarized in the tables below: Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value at December 31, 2017 Corporate debt securities $ 707,652 $ 150 $ (2,553 ) $ 705,249 Commercial paper 24,566 — — 24,566 U.S. government agency securities 472,593 — (1,975 ) 470,618 Foreign and other 25,540 150 (64 ) 25,626 Total $ 1,230,351 $ 300 $ (4,592 ) $ 1,226,059 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value at December 31, 2016 Certificates of deposit $ 2,800 $ — $ — $ 2,800 Corporate debt securities 641,670 329 (2,282 ) 639,717 Commercial paper 16,075 — — 16,075 U.S. government agency securities 310,635 37 (747 ) 309,925 Foreign and other 48 86 — 134 Total $ 971,228 $ 452 $ (3,029 ) $ 968,651 The fair values of available-for-sale securities by contractual maturity were as follows: December 31, 2017 2016 Maturing in one year or less $ 840,274 $ 395,940 Maturing after one year through five years 385,785 572,711 Total $ 1,226,059 $ 968,651 Impairment assessments are made at the individual security level each reporting period. When the fair value of an investment is less than its cost at the balance sheet date, a determination is made as to whether the impairment is other-than-temporary and, if it is other-than-temporary, an impairment loss is recognized in earnings equal to the difference between the investment’s amortized cost and fair value at such date. As of December 31, 2017, some of the Company’s investments were in an unrealized loss position. However, the Company has the ability and intent to hold all investments that have been in a continuous loss position until maturity or recovery, thus no other-than-temporary impairment was deemed to have occurred. See Note 12 to these Consolidated Financial Statements for additional discussion regarding the fair value of the Company’s available-for-sale securities.

INTANGIBLE ASSETS

INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS	(7) INTANGIBLE ASSETS Intangible assets consisted of the following: December 31, 2017 2016 Intangible assets: Finite-lived intangible assets $ 303,298 $ 305,122 Indefinite-lived intangible assets 326,359 332,199 Gross intangible assets: 629,657 637,321 Less: Accumulated amortization (112,147 ) (83,541 ) Net carrying value $ 517,510 $ 553,780 Finite-Lived Intangible Assets The following table summarizes the net-book-value and estimated remaining life of the Company’s finite-lived intangible assets as of December 31, 2017: Net Balance at December 31, 2017 Average Remaining Life Repurchased royalty rights $ 39,938 5.9 years Acquired intellectual property 149,229 7.2 years License payments for marketing approvals 1,357 4.4 years In-place and above market tenant leases 627 0.7 - 5.6 years Total $ 191,151 As of December 31, 2017, the estimated future amortization expense associated with the Company’s finite-lived intangible assets for each of the five succeeding fiscal years was as follows: Fiscal Year Amount 2018 $ 30,400 2019 30,086 2020 27,605 2021 26,681 2022 26,657 Thereafter 49,722 $ 191,151 Indefinite-Lived Intangible Assets Indefinite-lived intangible assets consisted of the following: December 31, 2017 2016 In-Process Research and Development: Pegvaliase $ 326,359 $ 326,359 Other acquired pre-clinical compounds — 5,840 Net carrying value $ 326,359 $ 332,199 Intangible assets related to IPR&D assets are considered to be indefinite-lived until the completion or abandonment of the associated R&D efforts. The Company recognized an impairment charge of $5.8 million related to acquired IPR&D assets during the fourth quarter of 2017, which was included in Intangible Asset Amortization and Contingent Consideration in the Consolidated Statements of Operations. In 2016 and 2015, the Company recorded impairment charges of $574.1 million and $198.7 million, respectively, related to the Kyndrisa and other exon IPR&D assets based on the status of development efforts. These impairments reduced the remaining book value to zero due to the termination of the programs. In 2016, the Company also recognized an impairment charge of $25.0 million related to the reveglucosidase alfa IPR&D assets due to the decision to terminate that development program. In December 2017, the Company sold the Rare Pediatric Disease Priority Review Voucher (PRV) it received from the FDA in connection with the U.S. approval of Brineura. In exchange for the voucher the Company received $125.0 million from Novartis Pharma AG. The proceeds from the sale of the PRV were recognized as a gain on the sale of intangible asset as the PRV did not have a carrying value on the Company’s Consolidated Balance Sheet at the time of sale.

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	(8) PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment, net, consisted of the following: December 31, 2017 2016 Building and improvements $ 663,347 $ 510,805 Manufacturing and laboratory equipment 294,521 242,899 Computer hardware and software 144,268 129,506 Leasehold improvements 42,572 44,184 Furniture and equipment 31,515 27,229 Land improvements 5,331 4,881 Land 62,369 55,412 Construction-in-progress 59,511 126,446 1,303,434 1,141,362 Less: Accumulated depreciation $ (406,734 ) (342,594 ) Total property, plant and equipment, net $ 896,700 $ 798,768 The construction-in-process balance primarily includes costs related to the Company’s significant in-process projects at its facilities in Marin County, California, and in Shanbally, Ireland. Depreciation for the years ended December 31, 2017, 2016 and 2015 was $75.8 million, $73.2 million and $50.1 million, respectively, of which $24.1 million, $17.4 million and $14.6 million was capitalized into inventory, respectively. Capitalized interest related to the Company’s property, plant and equipment purchases for each of the three years ended December 31, 2017 was insignificant.

INVENTORY

INVENTORY	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
INVENTORY	(9) INVENTORY Inventory consisted of the following: December 31, 2017 2016 Raw materials $ 49,877 $ 51,250 Work-in-process 234,674 167,788 Finished goods 191,224 136,088 Total inventory $ 475,775 $ 355,126

SUPPLEMENTAL BALANCE SHEET INFO

SUPPLEMENTAL BALANCE SHEET INFORMATION	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
SUPPLEMENTAL BALANCE SHEET INFORMATION	(10) SUPPLEMENTAL BALANCE SHEET INFORMATION Accounts payable and accrued liabilities consisted of the following: December 31, 2017 2016 Accounts payable and accrued operating expenses $ 166,616 $ 191,353 Accrued compensation expense 140,781 109,038 Accrued rebates payable 36,472 34,737 Accrued royalties payable 18,820 15,151 Value added taxes payable 9,740 7,848 Forward foreign currency exchange contracts 14,464 5,201 Accrued income taxes 5,528 — Other 9,500 7,177 Total accounts payable and accrued liabilities $ 401,921 $ 370,505 The roll forward of significant estimated accrued rebates and reserve for cash discounts for the years ended December 31, 2017, 2016 and 2015 were as follows: Balance at Beginning of Period Provision for Current Period Sales Provision/ (Reversals) for Prior Period Sales Actual Charges Related to Current Period Sales Actual Charges Related to Prior Period Sales Balance at End of Period Year ended December 31, 2017: Accrued rebates $ 34,737 $ 56,282 $ (3,686 ) $ (31,714 ) $ (19,147 ) $ 36,472 Reserve for cash discounts 888 10,730 (58 ) (9,601 ) (904 ) 1,055 Year ended December 31, 2016: Accrued rebates $ 32,553 $ 44,347 $ (5,205 ) $ (23,879 ) $ (13,079 ) $ 34,737 Reserve for cash discounts 831 8,889 (22 ) (8,160 ) (650 ) 888 Year ended December 31, 2015: Accrued rebates $ 14,859 $ 45,356 $ (1,245 ) $ (18,421 ) $ (7,996 ) $ 32,553 Reserve for cash discounts 688 7,402 — (6,722 ) (537 ) 831

DERIVATIVE INSTRUMENTS AND HEDG

DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES	12 Months Ended
	Dec. 31, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES	(11) DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES Foreign Currency Exchange Rate Exposure The Company uses forward foreign currency exchange contracts to hedge certain operational exposures resulting from potential changes in foreign currency exchange rates. Such exposures result from portions of the Company’s forecasted revenues and operating expenses being denominated in currencies other than the U.S. dollar, primarily the Euro. The Company designates certain of these forward foreign currency exchange contracts as hedging instruments and enters into some forward foreign currency exchange contracts that are considered to be economic hedges that are not designated as hedging instruments. Whether designated or undesignated, these forward foreign currency exchange contracts protect against the reduction in value of forecasted foreign currency cash flows resulting from product revenues, royalty revenues, operating expenses and asset or liability positions designated in currencies other than the U.S. dollar. The fair values of forward foreign currency exchange contracts are estimated using current exchange rates and interest rates, and take into consideration the current creditworthiness of the counterparties or the Company, as applicable. Information regarding the specific instruments used by the Company to hedge its exposure to foreign currency exchange rate fluctuations is provided below. See Note 12 to these Consolidated Financial Statements for additional discussion regarding the fair value of forward foreign currency exchange contracts. The Company enters into forward foreign currency exchange contracts in order to protect against the fluctuations in revenue and operating expenses associated with foreign currency-denominated cash flows. The Company has formally designated these forward foreign currency exchange contracts as cash flow hedges and expects them to be highly effective in offsetting fluctuations in operating expenses denominated in Euros and revenues denominated in currencies other than the U.S. dollar related to changes in foreign currency exchange rates. The following table summarizes the Company ’ Aggregate Notional Number of Amount in Foreign Exchange Contracts Contracts Foreign Currency Maturity Brazilian Reais – Sell 6 160.0 May 2018 Canadian Dollars – Sell 24 27.2 Jan. 2018 - Dec. 2018 Colombian Pesos – Sell 12 93,000.0 Jan. 2018 - Dec. 2018 Euros – Purchase 80 122.2 Jan. 2018 - Dec. 2020 Euros – Sell 289 373.5 Jan. 2018 - Dec. 2020 Total 411 The maximum length of time over which the Company is hedging its exposure to the reduction in value of forecasted foreign currency revenues through forward foreign currency exchange contracts is through December 2020. Over the next twelve months, the Company expects to reclassify $12.1 million from Accumulated Other Comprehensive Income (Loss) to earnings as the forecasted revenue and operating expense transactions occur. The following table summarizes the Company ’ Aggregate Notional Number of Amount in Foreign Exchange Contracts Contracts Foreign Currency Maturity British Pounds – Sell 1 5.0 January 2018 Euros – Purchase 4 93.5 January 2018 Total 5 The fair value carrying amounts of the Company’s derivative instruments were as follows: Asset Derivatives Liability Derivatives December 31, 2017 December 31, 2017 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments: Forward foreign currency exchange contracts Other current assets $ 4,015 Accounts payable & accrued liabilities $ 14,420 Forward foreign currency exchange contracts Other assets 4,973 Other long- term liabilities 12,686 Total $ 8,988 $ 27,106 Derivatives not designated as hedging instruments: Forward foreign currency exchange contracts Other current assets $ 675 Accounts payable & accrued liabilities $ 44 Total 675 44 Total value of derivative contracts $ 9,663 $ 27,150 Asset Derivatives Liability Derivatives December 31, 2016 December 31, 2016 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments: Forward foreign currency exchange contracts Other current assets $ 13,048 Accounts payable & accrued liabilities $ 5,176 Forward foreign currency exchange contracts Other assets 8,194 Other long- term liabilities 2,342 Total $ 21,242 $ 7,518 Derivatives not designated as hedging instruments: Forward foreign currency exchange contracts Other current assets $ 964 Accounts payable & accrued liabilities $ 25 Total 964 25 Total value of derivative contracts $ 22,206 $ 7,543 The effect of the Company’s derivative instruments on the Consolidated Financial Statements for the years ended December 31, 2017, 2016 and 2015 was as follows: Years Ended December 31, 2017 2016 2015 Derivatives Designated as Hedging Instruments: Net gain (loss) recognized in accumulated other comprehensive loss (1) $ (38,351 ) $ 9,677 $ 17,300 Net gain (loss) reclassified from accumulated other comprehensive income (loss) into earnings (2) (5,113 ) 6,529 19,604 Net gain (loss) recognized in net loss (3) 2,576 5,070 (727 ) Derivatives Not Designated as Hedging Instruments: Net gain (loss) recognized in net loss (4) $ 8,255 $ (8,687 ) $ 4,493 (1) Net change in the fair value of the effective portion classified as accumulated other comprehensive income (loss). (2) Effective portion classified as Net Product Revenues and SG&A expense. (3) Ineffective portion and amount excluded from effectiveness testing classified as SG&A expense. (4) Classified as SG&A expense. The Company is exposed to counterparty credit risk on all of its derivative financial instruments. The Company has established and maintains strict counterparty credit guidelines and enters into hedges only with financial institutions that are investment grade or better to minimize the Company’s exposure to potential defaults. The Company does not require collateral to be pledged under these agreements.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	(12) FAIR VALUE MEASUREMENTS The Company measures certain financial assets and liabilities at fair value on a recurring basis, including available-for-sale fixed income securities and foreign currency derivatives. The tables below present the fair value of these financial assets and liabilities determined using the following input levels. Fair Value Measurements at December 31, 2017 Quoted Price in Active Markets For Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets: Cash equivalents (including available-for-sale debt securities): Money market instruments — 215,441 — 215,441 Corporate debt securities — 3,096 — 3,096 Commercial paper — 2,751 — 2,751 U.S. government agency securities — 35,497 — 35,497 Foreign and other — 990 — 990 Total cash and cash equivalents — 257,775 — 257,775 Available-for-sale debt securities: Short-term: Corporate debt securities — 406,188 — 406,188 Commercial paper — 21,815 — 21,815 U.S. government agency securities — 345,501 — 345,501 Foreign and other — 24,436 — 24,436 Long-term: Corporate debt securities — 295,965 — 295,965 U.S. government agency securities — 89,620 — 89,620 Foreign and other — 200 — 200 Total available-for-sale debt securities — 1,183,725 — 1,183,725 Other Current Assets: NQDC Plan assets — 967 — 967 Forward foreign currency exchange contract (1) — 4,690 — 4,690 Restricted investments (2) — 15,647 — 15,647 Total other current assets — 21,304 — 21,304 Other Assets: NQDC Plan assets — 11,859 — 11,859 Forward foreign currency exchange contract (1) — 4,973 — 4,973 Total other assets — 16,832 — 16,832 Total assets $ — $ 1,479,636 $ — $ 1,479,636 Liabilities: Current Liabilities: NQDC Plan liability $ 1,356 $ 967 $ — $ 2,323 Forward foreign currency exchange contract (1) — 14,464 — 14,464 Contingent acquisition consideration payable — — 53,648 53,648 Total current liabilities 1,356 15,431 53,648 70,435 Other long-term liabilities: NQDC Plan liability 18,272 11,859 — 30,131 Forward foreign currency exchange contract (1) — 12,686 — 12,686 Contingent acquisition consideration payable — — 135,318 135,318 Total other long-term liabilities 18,272 24,545 135,318 178,135 Total liabilities $ 19,628 $ 39,976 $ 188,966 $ 248,570 Fair Value Measurements at December 31, 2016 Quoted Price in Active Markets For Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets: Cash equivalents (including available-for-sale debt securities): Money market instruments — 235,571 — 235,571 Corporate debt securities — 8,593 — 8,593 U.S. government agency securities — 6,000 — 6,000 Total cash and cash equivalents — 250,164 — 250,164 Available-for-sale debt securities: Short-term: Certificates of deposit — 2,800 — 2,800 Corporate debt securities — 193,974 — 193,974 Commercial paper — 16,075 — 16,075 U.S. government agency securities — 168,498 — 168,498 Long-term: Corporate debt securities — 437,150 — 437,150 U.S. government agency securities — 135,427 — 135,427 Foreign and other — 134 — 134 Total available-for-sale debt securities — 954,058 — 954,058 Other Current Assets: Nonqualified Deferred Compensation Plan assets — 163 — 163 Forward foreign currency exchange contract (1) — 14,012 — 14,012 Restricted investments (2) — 3,754 — 3,754 Total other current assets — 17,929 — 17,929 Other Assets: Nonqualified Deferred Compensation Plan assets — 9,121 — 9,121 Forward foreign currency exchange contract (1) — 8,194 — 8,194 Strategic investment (3) 4,064 — — 4,064 Total other assets 4,064 17,315 — 21,379 Total assets $ 4,064 $ 1,239,466 $ — $ 1,243,530 Liabilities: Current Liabilities: Nonqualified Deferred Compensation Plan liability $ 2,073 $ 163 $ — $ 2,236 Forward foreign currency exchange contract (1) — 5,201 — 5,201 Contingent acquisition consideration payable — — 46,327 46,327 Total current liabilities 2,073 5,364 46,327 53,764 Other long-term liabilities: Nonqualified Deferred Compensation Plan liability 17,303 9,121 — 26,424 Forward foreign currency exchange contract (1) — 2,342 — 2,342 Contingent acquisition consideration payable — — 115,310 115,310 Total other long-term liabilities 17,303 11,463 115,310 144,076 Total liabilities $ 19,376 $ 16,827 $ 161,637 $ 197,840 (1) See Note 11 to these Consolidated Financial Statements for further information regarding the derivative instruments. (2) The restricted investments as of December 31, 2017 and 2016 secure the Company’s irrevocable standby letter of credit obtained in connection with certain commercial agreements. (3) The Company had investments in marketable equity securities measured using quoted prices in an active market that are considered strategic investments and included in Other Assets on the Company’s Balance Sheets. As of December 31, 2017, all holdings in the Company’s strategic investments have been liquidated. There were no transfers between levels during the year ended December 31, 2017. The Company’s Level 2 securities are valued using third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities, issuer credit spreads, benchmark securities, prepayment/default projections based on historical data and other observable inputs. The Company validates the prices provided by its third-party pricing services by understanding the models used, obtaining market values from other pricing sources, analyzing pricing data in certain instances and confirming those securities traded in active markets. See Note 6 to these Consolidated Financial Statements for further information regarding the Company’s financial instruments. Liabilities measured at fair value using Level 3 inputs consisted of contingent acquisition consideration payable and asset retirement obligations. The Company’s contingent acquisition consideration payable is estimated using a probability-based income approach utilizing an appropriate discount rate. Key assumptions used by management to estimate the fair value of contingent acquisition consideration payable include estimated probabilities, the estimated timing of when a milestone may be attained and assumed discount periods and rates. Subsequent changes in the fair value of the contingent acquisition consideration payable, resulting from management’s revision of key assumptions, will be recorded in Intangible Asset Amortization and Contingent Consideration in the Company’s Consolidated Statements of Comprehensive Loss. The probability-based income approach used by management to estimate the fair value of the contingent acquisition consideration is most sensitive to changes in the estimated probabilities. Contingent acquisition consideration payable at December 31, 2016 $ 161,637 Milestone payments to former Huxley Pharmaceuticals, Inc. shareholders (3,500 ) Reversal of contingent liability related to revised estimate of Firdapse FDA acceptance and approval milestones (4,245 ) Changes in the fair value of other contingent acquisition consideration payable 14,587 Foreign exchange remeasurement of Euro denominated contingent acquisition consideration payable 20,487 Contingent acquisition consideration payable at December 31, 2017 $ 188,966 Under certain of the Company’s lease agreements, the Company is contractually obligated to return leased space to its original condition upon termination of the lease agreement. The Company records an asset retirement obligation liability and a corresponding capital asset in an amount equal to the estimated fair value of the obligation, when estimable. In subsequent periods, for each such lease, the Company records interest expense to accrete the asset retirement obligation liability to full value and depreciates each capitalized asset retirement obligation asset, both over the term of the associated lease agreement. As of December 31, 2017, the balance of the asset retirement obligation liability was $4.2 million. The Company acquired intangible assets as a result of various business acquisitions. The estimated fair value of these long-lived assets was measured using Level 3 inputs as of the acquisition date.

DEBT

DEBT	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
DEBT	(13) DEBT 2024 Convertible Notes In August 2017, the Company issued $495.0 million in aggregate principal amount of senior subordinated convertible notes with a maturity date of August 1, 2024 (the 2024 Notes). The 2024 Notes were issued to the public at 98% of face value and bear interest at the rate of 0.599% per annum. The effective interest rate on the 2024 Notes the year ended December 31, 2017 was 1.1%. Interest is payable semi-annually in cash on February 1 and August 1 of each year, beginning February 1, 2018. The 2024 Notes are convertible, at the option of the holder into shares of the Company’s common stock. The initial conversion rate for the 2024 Notes is 8.0212 shares per $1,000 principal amount of the 2024 Notes, which represents a conversion price of approximately $124.67 per share, subject to adjustment under certain conditions. Following certain corporate transactions, the Company will, in certain circumstances, increase the conversion rate for a holder that elects to convert its 2024 Notes in connection with such corporate transactions by a number of additional shares of the Company’s common stock. A holder may convert fewer than all of such holder’s 2024 Notes so long as the amount of the 2024 Notes converted is an integral multiple of $1,000 principal amount. Net proceeds from the offering were $481.7 million. The 2024 Notes are senior subordinated, unsecured obligations, and rank (i) subordinated in right of payment to the prior payment in full of any of the Company’s existing and future senior debt, (ii) equal in right of payment to any of the Company’s existing and future senior subordinated debt, (iii) senior in right of payment to any of the Company’s existing and future indebtedness that is expressly subordinated in right of payment to the 2024 Notes, and (iv) effectively subordinated to any of the Company’s existing and future secured indebtedness, to the extent of the value of the collateral securing that indebtedness and structurally subordinated to all existing and future indebtedness and other liabilities, including trade payables, and (to the extent the Company is not a holder thereof) preferred equity, if any, of the Company’s subsidiaries. Upon the occurrence of a “fundamental change,” as defined in the indenture governing the 2024 Notes, the holders may require the Company to repurchase all or a portion of such holder’s 2024 Notes for cash at 100% of the principal amount of the 2024 Notes being purchased, plus any accrued and unpaid interest. In connection with the issuance of the 2024 Notes, the Company recorded a discount on the 2024 Notes of $9.9 million, which will be accreted and recorded as additional interest expense over the life of the 2024 Notes. In connection with the issuance of the 2024 Notes, the Company incurred $3.4 million of issuance costs. These costs were deferred and are being amortized over the life of the 2024 Notes and recorded as additional interest expense. 2018/2020 Convertible Notes On October 15, 2013, the Company issued $750.0 million in aggregate principal amount of senior subordinated convertible notes consisting of $375.0 million in aggregate principal amount of 0.75% senior subordinated convertible notes with a maturity date of October 15, 2018 (the 2018 Notes) and $375.0 million in aggregate principal amount of 1.50% senior subordinated convertible notes with a maturity date of October 15, 2020 (the 2020 Notes). Net proceeds from the offering were $726.2 million. The 2018 Notes and the 2020 Notes bear interest at a rate of 0.75% and 1.50% per year, respectively, which is payable semiannually in arrears on April 15 and October 15 of each year. The effective interest rate on the 2018 Notes and 2020 Notes the year ended December 31, 2017 was 6.0% and 7.5%, respectively. The 2018 Notes and the 2020 Notes are senior unsecured obligations, and rank (i) subordinated to any of the Company’s existing and future unsecured senior debt, (ii) equally to any of the Company’s existing and future senior subordinated debt, (iii) senior to any of the Company’s future indebtedness that is expressly subordinated to the 2018 Notes and the 2020 Notes, and (iv) effectively junior to any secured indebtedness to the extent of the value of the assets securing such indebtedness. Upon the occurrence of a “fundamental change”, as defined in the indenture, the holders may require the Company to repurchase all or a portion of the 2018 Notes and the 2020 Notes for cash at 100% of the principal amount of the Notes being purchased, plus any accrued and unpaid interest. The initial conversion rate for the 2018 Notes is 10.6213 shares per $1,000 principal amount of the 2018 Notes, which represents a conversion price of approximately $94.15 per share, and the initial conversion rate for the 2020 Notes is 10.6213 shares per $1,000 principal amount of the 2020 Notes, which represents a conversion price of approximately $94.15 per share, Such conversion rates are subject to adjustment under certain conditions. Holders may convert their 2018 Notes or 2020 Notes at their option at any time prior to July 15, 2018, in the case of the 2018 Notes, and July 15, 2020, in the case of the 2020 Notes, only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on March 31, 2014 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the applicable conversion price on each applicable trading day; (2) during the five business day period after any five consecutive trading day period (the measurement period) in which the trading price per $1,000 principal amount of the relevant notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the applicable conversion rate on each such trading day; or (3) upon the occurrence of specified corporate events. On or after July 15, 2018, in the case of the 2018 Notes, or July 15, 2020, in the case of the 2020 Notes, until the close of business on the second scheduled trading day immediately preceding the applicable maturity date, holders may convert their notes at any time, regardless of the foregoing circumstances. Upon conversion of the 2018 Notes and the 2020 Notes, the Company may pay cash, shares of the Company’s common stock or a combination of cash and stock, as determined by the Company in its discretion. The Company has separately accounted for the liability and equity components of the 2018 Notes and the 2020 Notes by allocating the proceeds from issuance of the 2018 Notes and the 2020 Notes between the liability component and the embedded conversion option, or equity component. This allocation was done by first estimating an interest rate at the time of issuance for similar notes that do not include the embedded conversion option. The Company allocated $156.2 million to the equity component, net of offering costs of $5.1 million. The Company recorded a discount on the notes of $161.3 million which will be accreted and recorded as additional interest expense over the life of the 2018 Notes and the 2020 Notes. Additionally, in connection with the issuance of the 2018 Notes and the 2020 Notes, the Company incurred $23.8 million of issuance costs, which are being amortized and recorded as additional interest expense over the life of the Notes. To minimize the impact of potential dilution upon conversion of the 2018 Notes and the 2020 Notes, the Company entered into capped call transactions separate from the issuance of the Notes with certain counterparties covering 3,982,988 shares of the Company’s common stock, subject to adjustment. The capped calls have a strike price of $94.15 and a cap price of $121.05 and are exercisable when and if the Notes are converted. If upon conversion of the Notes, the price of the Company’s common stock is above the strike price of the capped calls, the counterparties will deliver shares of the Company’s common stock and/or cash with an aggregate value equal to the difference between the price of the Company’s common stock at the conversion date and the strike price, multiplied by the number of shares of the Company’s common stock related to the capped calls being exercised. The Company paid $29.8 million for these capped calls transactions, which was recorded as additional paid-in capital. 2017 Convertible Notes In April 2007, the Company sold $324.9 million in aggregate principal amount of senior subordinated convertible notes due in April 2017 (the 2017 Notes). The 2017 Notes were issued at face value and bore interest at the rate of 1.875% per annum, payable semi-annually in cash. The 2017 Notes were convertible, at the option of the holder, at any time prior to maturity or repurchase, into shares of the Company’s common stock at a conversion rate of 49.1171 shares per $1,000 principal amount of the 2017 Notes, which is equal to a conversion price of approximately $20.36 per share, subject to adjustment in certain circumstances. The 2017 Notes did not include a call provision and the Company was unable to unilaterally redeem the 2017 Notes prior to maturity on April 23, 2017. During the twelve months ended December 31, 2017, 2016 and 2015, certain existing holders of the 2017 Notes elected to convert $22.5 million, $8.9 million and $8.1 million in aggregate principal amount of the 2017 Notes into 1,103,998, 438,462 and 399,469 shares, respectively, of the Company ’ The following table summarizes information regarding the Company’s convertible debt at December 31: 2017 2016 Convertible Notes due 2017 $ — $ 22,503 Unamortized deferred offering costs — (25 ) Convertible Notes due 2017, net — 22,478 Convertible Notes due 2018 374,980 374,980 Unamortized discount (12,488 ) (27,566 ) Unamortized deferred offering costs (1,543 ) (3,484 ) Convertible Notes due 2018, net 360,949 343,930 Convertible Notes due 2020 374,993 374,993 Unamortized discount (40,287 ) (53,239 ) Unamortized deferred offering costs (3,631 ) (4,923 ) Convertible Notes due 2020, net 331,075 316,831 Convertible Notes due in 2024 495,000 — Unamortized discount (9,355 ) — Unamortized deferred offering costs (3,199 ) — Convertible Notes due in 2024, net 482,446 — Total convertible debt, net $ 1,174,470 $ 683,239 Fair value of fixed rate convertible debt Convertible Notes due in 2017 (1) $ — $ 90,977 Convertible Notes due in 2018 (1) 403,955 423,202 Convertible Notes due in 2020 (1) 446,470 442,754 Convertible Notes due in 2024 (1) 493,894 — Total $ 1,344,319 $ 956,933 (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. See Note 14 to these Consolidated Financial Statements for further discussion of the effect of conversion on net loss per common share. Revolving Credit Facility In November 2016, the Company entered into a credit agreement (Credit Agreement) providing for up to $100.0 million (Revolving Credit Facility), a $10.0 million letter of credit subfacility and a $15.0 million swing line loan subfacility. The maturity date of the Revolving Credit Facility will occur on November 29, 2018. Interest on any outstanding balance of the Revolving Credit Facility is payable quarterly and draws may be voluntary prepaid at any time without penalty. In connection with entering into the Credit Agreement, $0.6 million in financing costs was incurred and will be amortized as Interest Expense over the term of the Credit Agreement. As of December 31, 2017, there were no outstanding amounts due under the Revolving Credit Facility. In connection with the Revolving Credit Facility, the Company and certain of its subsidiaries are required to comply with covenants, including, among other things, restrictions on the Company’s and such subsidiaries’ ability to incur additional indebtedness, dispose of its assets, incur liens, make investments, and pay dividends or other distributions, in each case subject to specified exceptions. The Credit Agreement also contains customary indemnification obligations and customary events of default. If the Company’s Global Liquidity, which is defined as the sum of the market value of unrestricted cash, marketable securities and other assets to the extent constituting “cash and cash equivalents,” “short-term investments” or “long-term investments” as reflected in the Company’s Consolidated Balance Sheet, in each case, held by the Company or certain of the Company’s subsidiaries at such time, regardless of where such assets are domiciled, falls below $225.0 million at the end of any month or at the time of any borrowing or issuance of a letter of credit under the Revolving Credit Facility, then the Company’s obligations under the Credit Agreement will also be secured by the assets held by the Company in the custody account, which was established in the first quarter of 2017. As of December 31, 2017, the Company and certain of its subsidiaries that serve as guarantors are in compliance with all covenants. Interest expense on the Company’s debt consisted of the following: Years Ended December 31, 2017 2016 2015 Coupon interest $ 10,407 $ 9,555 $ 9,750 Amortization of debt issuance costs 3,725 3,367 3,294 Accretion of discount on convertible notes 28,575 26,577 25,200 Total interest expense on convertible debt $ 42,707 $ 39,499 $ 38,244

NET LOSS PER COMMON SHARE

NET LOSS PER COMMON SHARE	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
NET LOSS PER COMMON SHARE	(14) NET 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 ESPP, unvested restricted stock units (RSUs), common stock held by the NQDC and contingent issuances of common stock related to convertible debt. The following table sets forth the computation of basic and diluted earnings per common share (in thousands of common shares): Years Ended December 31, 2017 2016 2015 Numerator: Net loss, basic $ (117,042 ) $ (630,210 ) $ (171,799 ) Less: gain on common stock held by the NQDC — (3,184 ) — Net loss, diluted (117,042 ) (633,394 ) (171,799 ) Denominator: Weighted-average common shares outstanding, basic 174,427 165,985 160,025 Effect of dilutive securities: Common stock held by the NQDC — 234 — Weighted-average common shares outstanding, diluted 174,427 166,219 160,025 Net loss per common share, basic $ (0.67 ) $ (3.80 ) $ (1.07 ) Net loss per common share, diluted $ (0.67 ) $ (3.81 ) $ (1.07 ) The table below presents potential shares of common stock that were excluded from the computation of basic and diluted earnings per common share as they were anti-dilutive using the if-converted or treasury stock method (in thousands): Years Ended December 31, 2017 2016 2015 Options to purchase common stock 8,108 8,856 10,323 Common stock issuable under the 2017 Notes — 1,105 1,544 Common stock issuable under the 2018 Notes 3,983 3,983 3,983 Common stock issuable under the 2020 Notes 3,983 3,983 3,983 Common stock issuable under the 2024 Notes 3,970 — — Unvested restricted stock units 2,911 2,618 1,743 Common stock potentially issuable for ESPP purchases 436 404 312 Common stock held by the NQDC 220 — 243 Total number of potentially issuable shares 23,611 20,949 22,131 The potential effect of the capped call transactions with respect to the 2018 Notes and the 2020 Notes was excluded from the diluted net income/loss per share as the Company’s closing stock price on December 31, 2017 and 2016 did not exceed the conversion price of $94.15 per share for the 2018 Notes and the 2020 Notes. Although the Company’s stock price exceeded the conversion price $94.15 at December 31, 2015, the potential shares issuable under the 2018 Notes and the 2020 Notes were excluded from the calculation of diluted loss per share as they were anti-dilutive using the if-converted method. There is no similar capped call transaction associated with the 2024 Notes. See Note 13 to these Consolidated Financial Statements for information on the Company’s debt.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
INCOME TAXES	(15) INCOME TAXES The provision for (benefit from) income taxes is based on loss before income taxes as follows: Years Ended December 31, 2017 2016 2015 U.S. Source $ (19,461 ) $ 10,696 $ 182,215 Non-U.S. Source (16,414 ) (841,746 ) (336,939 ) Loss before income taxes $ (35,875 ) $ (831,050 ) $ (154,724 ) The U.S. and foreign components of the provision for (benefit from) income taxes are as follows: Years Ended December 31, 2017 2016 2015 Provision for current income tax expense: Federal $ 29,848 $ 22,239 $ 84,743 State and local 2,880 1,418 5,323 Foreign 3,975 3,557 3,836 36,703 27,214 93,902 Provision for (benefit from) deferred income tax expense: Federal 12,446 (78,428 ) (17,741 ) State and local 32,336 (6,012 ) (8,770 ) Foreign (318 ) (143,614 ) (50,316 ) 44,464 (228,054 ) (76,827 ) Provision for (benefit from) income taxes $ 81,167 $ (200,840 ) $ 17,075 On December 22, 2017, the bill known as the Tax Cuts and Jobs Act (the 2017 Tax Act) was signed into law. The new law has resulted in significant changes to the U.S. corporate income tax system. These changes include a federal statutory rate reduction from 35% to 21% The Company’s deferred tax assets and liabilities are measured at the enacted tax rate expected to apply when these temporary differences are expected to be realized or settled. The Company recorded a provisional expense of $42.3 million related to the 2017 Tax Act, which included $33.1 million for the re-measurement of the net deferred tax assets at the lower enacted corporate tax rate and $9.2 million related to the increased limitations on executive compensation. The Company also assessed the impact of the 2017 Tax Act on its financial projections and concluded that is more likely than not that certain of its state tax credits will not be utilized in the foreseeable future, and recognized $41.4 million of income tax expense during the fourth quarter of 2017 to establish a valuation allowance against those state tax credits. These credits do not expire, however, the Company projects that it will be generating more credits than it will utilize on an annual basis. The incremental net income tax expense recognized as a result of the 2017 Tax Act was an estimate and the measurement of deferred tax assets is subject to further analysis and potential correlative adjustments as developing interpretations and guidance from the U.S. Treasury Department, the IRS, and other standard setting bodies provide additional clarifications of the provisions of the 2017 Tax Act. Updated guidance and regulations For the year ended December 31, 2016, the Company’s Dutch operations had a book net loss of $539.2 million, which included the impairment of the Kyndrisa IPR&D assets and a resulting deferred tax benefit of $143.5 million associated with the reversal of the deferred tax liability of such IPR&D assets. The following is a reconciliation of the statutory federal income tax rate to the Company’s effective income tax rate expressed as a percentage of loss before income taxes: Years Ended December 31, 2017 2016 2015 Federal statutory income tax rate 35.0 % 35.0 % 35.0 % State and local taxes (20.3 )% 0.4 % (2.2 )% Orphan Drug & General Business Credit 93.9 % 7.5 % 34.8 % Stock compensation expense 19.1 % 4.6 % (2.8 )% Changes in the fair value of contingent acquisition consideration payable (3.1 )% 0.9 % 0.2 % Subpart F income (84.1 )% — % (8.4 )% Foreign tax rate differential (26.2 )% (18.6 )% (46.2 )% Section 162(m) limitation (26.5 )% (5.4 )% (1.3 )% Tax Cuts and Jobs Act of 2017 (118.0 )% — % — % Other 1.9 % 0.3 % (1.6 )% Valuation allowance/deferred benefit (97.9 )% (0.5 )% (18.5 )% Effective income tax rate (226.2 )% 24.2 % (11.0 )% The significant components of the Company’s net deferred tax assets are as follows: December 31, 2017 2016 Net deferred tax assets: Net operating loss carryforwards $ 48,374 $ 49,787 Tax credit carryforwards 384,381 352,535 Accrued expenses, reserves, and prepaids 54,565 77,904 Intangible assets 17,556 26,751 Stock-based compensation 31,371 47,713 Inventory 13,206 15,581 Impairment 2,609 5,017 Other 2,358 1,519 Valuation allowance (111,001 ) (73,037 ) Total deferred tax assets 443,419 503,770 Joint venture basis difference (1,229 ) (1,714 ) Acquired intangibles (3,332 ) (8,773 ) Convertible notes discount (10,100 ) (24,394 ) Property, plant and equipment (29,663 ) (22,103 ) Total deferred tax liabilities (44,324 ) (56,984 ) Net deferred tax assets $ 399,095 $ 446,786 In 2017, the increase in the valuation allowance was primarily due to the state tax credits discussed above. The incremental expense was partially offset by a reduction in the valuation allowance related to fully valued assets that expired in 2017. As of December 31, 2017, the Company had the following net operating loss and tax credit carryforwards, which if not utilized, will expire as follows (dollars in thousands): Type Amount Year Federal net operating loss carryforwards $ 15,554 2028 – 2033 Federal R&D and orphan drug credit carryforwards $ 403,828 2030 – 2037 State net operating loss carryforwards $ 108,133 2019 – 2036 Dutch net operating loss carryforwards $ 145,150 2020 – 2025 The $9.5 million of Irish net operating losses and $83.7 million of state research credit carryovers will carry forward indefinitely. The Company’s net operating losses and credits could be subject to annual limitations due to ownership change limitations provided by IRC Section 382 and similar state provisions. An annual limitation could result in the expiration of net operating losses and tax credit carryforward before utilization. There are limitations on the tax attributes of acquired entities however, the Company does not believe the limitations will have a material impact on the utilization of the net operating losses or tax credits. The financial statement recognition of the benefit for a tax position is dependent upon the benefit being more likely than not to be sustainable upon audit by the applicable taxing authority. If this threshold is met, the tax benefit is then measured and recognized at the largest amount that is greater than 50% likely of being realized upon ultimate settlement. A reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2017 and 2016 is as follows: December 31, 2017 2016 Balance at beginning of period $ 103,210 $ 86,731 Additions based on tax positions related to the current year 11,042 15,982 (Deletions) Additions for tax positions of prior years (766 ) 497 Balance at end of period $ 113,486 $ 103,210 Included in the balance of unrecognized tax benefits at December 31, 2017 are potential benefits of $113.5 million that, if recognized, would affect the effective tax rate. The Company’s policy for classifying interest and penalties associated with unrecognized income tax benefits is to include such items in the income tax expense. The total amount of accrued interest and penalties was not significant as of December 31, 2017. The Company files income tax returns in the U.S. and various foreign jurisdictions. The U.S. and foreign jurisdictions have statute of limitations ranging from three to five years. However, carryforward tax attributes that were generated in 2014 and earlier may still be adjusted upon examination by tax authorities. Currently, the Company is under audit by the Internal Revenue Service for the year 2014. U.S. income and foreign withholding taxes have not been recognized on the excess of the amount for financial reporting over the tax basis of investments in foreign subsidiaries that are essentially permanent in duration. This excess totaled approximately $10.7 million as of December 31, 2017, which will be indefinitely reinvested; deferred income taxes have not been provided on such foreign earnings.

EQUITY COMPENSATION PLANS

EQUITY COMPENSATION PLANS	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
EQUITY COMPENSATION PLANS	(16) EQUITY COMPENSATION PLANS Share Incentive Plan The Company’s stock-based compensation plans include the 2017 Equity Incentive Plan and the ESPP. The 2017 Equity Incentive Plan, which was approved by the Company’s stockholders on June 6, 2017 and became effective that same date, and is the successor to and continuation of the Company’s Amended and Restated 2006 Share Incentive Plan (the 2006 Share Incentive Plan), provides for awards of RSUs and stock options as well as other forms of equity compensation. No additional awards will be granted under the 2006 Share Incentive Plan; however, there are vested and unvested awards outstanding under the 2006 Share Incentive Plan. Stock option awards granted to employees generally vest over a four-year period on a cliff basis twelve months after the grant date and then monthly thereafter. The contractual term of stock option awards is generally ten years from the grant date. RSUs granted to employees generally vest annually over a straight-line four-year period after the grant date. RSUs granted to directors generally vest in full one year after the grant date. Shares formerly reserved for future issuance under the 2006 Share Incentive Plan were transferred to the 2017 Equity Incentive Plan, from which future shares shall be issued. The Company’s stock-based compensation plans are administered by the Company’s Board of Directors, or designated Committee thereof, which selects persons to receive awards and determines the number of shares subject to each award and the terms, conditions, performance measures and other provisions of the awards. As of December 31, 2017, options to purchase approximately 8.1 million shares were outstanding under the Company’s stock option plans. As of December 31, 2017, approximately 10.9 million shares were authorized for future issuance under the 2017 Equity Incentive Plan. Employee Stock Purchase Plan Under BioMarin’s ESPP, which was initially approved in June 2006, replacing the Company’s previous plan, and was further amended on March 5, 2014, employees meeting specific employment qualifications are eligible to participate and can purchase shares on established dates (each purchase date) semi-annually through payroll deductions at the lower of 85% of the fair market value of the stock at the commencement of the offering period or each purchase date of the offering period. Each offering period will span up to two years. The ESPP permits eligible employees to purchase common stock through payroll deductions for up to 10% of qualified compensation, up to an annual limit of $25,000. The ESPP is intended to qualify as an “employee stock purchase plan” under Section 423 of the IRC. During the year ended December 31, 2017, the Company issued 0.2 million shares under the ESPP. As of December 31, 2017, there were approximately 3.5 million shares were authorized and 0.6 million shares reserved for future issuance under the ESPP. Board of Director Grants On September 28, 2017, the Board of Directors (the Board) approved revised compensation for the Independent Directors of the Company as follows. On the date of the Company’s annual meeting of stockholders for a given year, each re-elected Independent Director receives an RSU grant valued at $375,000, with the number of RSUs to be granted calculated based on the three month trailing average closing price of our common stock on the Nasdaq Global Select Market Prior to September 28, 2017, each Independent Director was automatically granted an initial equity grant valued at $550,000, with the number of equity awards to be granted calculated based on the three month trailing average closing price of our common stock on the Nasdaq Global Select Market See Note 3 to these Consolidated Financial Statements for discussion regarding the valuation of equity awards. Shares Available Under Equity Compensation Plans At December 31, 2017, an aggregate of approximately 30.0 million unissued shares was authorized for future issuance under the Company’s stock plans, which includes shares issuable under the 2017 Equity Incentive Plan, the ESPP and the Company’s expired plans. Under the 2017 Equity Incentive Plan, shares issued under the 2006 Share Incentive Plan and the 2017 Equity Incentive Plan that expire or are forfeited generally become available for future issuance under the 2017 Equity Incentive Plan.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
STOCK-BASED COMPENSATION	(17) STOCK-BASED COMPENSATION Stock Options The following table summarizes activity under the Company’s stock option plans, including the 2012 and 2014 Inducement Plans and those suspended upon the adoption of the 2017 Share Incentive Plan, for the year ended December 31, 2017. All option grants presented in the table had exercise prices not less than the fair value of the underlying common stock on the grant date: Shares Weighted Average Exercise Price Weighted Average Remaining Years Aggregate Intrinsic Value (1) Options outstanding as of December 31, 2016 8,856,208 $ 51.13 5.4 $ 304,356 Granted 801,170 $ 87.74 Exercised (1,367,307 ) $ 34.96 Expired and forfeited (182,090 ) $ 92.98 Options outstanding as of December 31, 2017 8,107,981 $ 56.53 5.1 $ 281,141 Options unvested at December 31, 2017 1,462,941 $ 88.19 8.5 $ 6,313 Exercisable at December 31, 2017 6,645,032 $ 49.56 4.3 $ 274,828 (1) The aggregate intrinsic value for outstanding options is calculated as the difference between the exercise price of the underlying awards and the quoted price of the Company’s common stock on the Nasdaq Global Select Market as of the last trading day for the respective year. The aggregate intrinsic value of options outstanding and exercisable includes options with an exercise price below $89.17, the closing price of the Company’s common stock on the Nasdaq Global Select Market on December 29, 2017, the last trading day of the year. The weighted-average fair value per option granted in the years ended December 31, 2017, 2016 and 2015 were $36.07, $40.70 and $56.76, respectively. The total intrinsic value of options exercised during the years ended December 31, 2017, 2016 and 2015 was $77.0 million, $127.4 million and $146.6 million, respectively. The aggregate intrinsic value of options exercised was determined as of the date of option exercise. Upon the exercise of the options, the Company issues new common stock from its authorized shares. There were 7.4 million options that were in-the-money at December 31, 2017. The assumptions used to estimate the per share fair value of stock options granted during the periods presented were as follows: Years Ended December 31, 2017 2016 2015 Expected volatility 38 – 40% 36 – 44% 36 – 45% Dividend yield 0.00% 0.00% 0.00% Expected life 4.9 – 6.6 years 5.0 – 8.1 years 6.4 – 8.0 years Risk-free interest rate 1.8 – 2.2% 1.1 – 2.3% 1.5 – 2.2% The Company recorded $36.7 million, $45.5 million and $41.5 million of compensation costs related to current period vesting of stock options for the years ended December 31, 2017, 2016 and 2015, respectively. As of December 31, 2017, the total unrecognized compensation cost related to unvested stock options was $49.2 million. These costs are expected to be recognized over a weighted average period of 2.4 years. The net tax benefit from stock options exercised during the year ended December 31, 2017 was $7.8 million. The assumptions used to estimate the per share fair value of stock purchase rights granted under the ESPP were as follows: Years Ended December 31, 2017 2016 2015 Expected volatility 28 – 42% 42 – 50% 36 – 38% Dividend yield 0.00% 0.00% 0.00% Expected life 6 – 24 months 6 – 24 months 6 – 24 months Risk-free interest rate 1.0 – 1.6% 0.4 – 0.8% 0.1 – 0.8% The Company recorded $11.7 million, $10.1 million and $7.1 million of compensation costs related to shares granted under the ESPP for the years ended December 31, 2017, 2016 and 2015, respectively. As of December 31, 2017, there was $12.9 million of total unrecognized compensation cost related to unvested stock options issuable under the ESPP. These costs are expected to be recognized over a weighted average period of 1.4 years. Restricted Stock Unit Awards with Service-Based Vesting Conditions RSUs are generally subject to forfeiture if employment terminates prior to the release of vesting restrictions. Below is a summary of RSU activity under the plan for the year ended December 31, 2017: Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Years Aggregate Intrinsic Value Non-vested units as of December 31, 2016 2,444,966 $ 92.70 1.4 $ 202,541 Granted 1,382,900 $ 87.88 Vested (837,926 ) $ 92.00 Forfeited (310,406 ) $ 96.02 Non-vested units as of December 31, 2017 2,679,534 $ 90.04 1.4 $ 238,934 The weighted-average grant date fair value per share of RSUs granted during the years ended December 31, 2017, 2016 and 2015, was $87.88, $84.18 and $119.86, respectively. The total intrinsic value of restricted stock that vested and was released in the years ended December 31, 2017, 2016 and 2015 was $76.5 million, $63.5 million and $59.5 million, respectively. The Company recorded $86.5 million, $74.7 million and $47.9 million of compensation costs related to RSUs with service-based vesting conditions for the years ended December 31, 2017, 2016 and 2015, respectively. As of December 31, 2017, there was $173.7 million of total unrecognized compensation cost related to unvested RSUs with service-based vesting conditions. These costs are expected to be recognized over a weighted average period of 1.3 years. Restricted Stock Unit Awards with Performance Conditions The Compensation Committee of the Board (with respect to awards to certain executive officers other than the Chief Executive Officer) and the Board (with respect to awards to the Chief Executive Officer) may grant RSUs with performance-based vesting conditions to certain executive officers. In March 2017, the Compensation Committee and Board approved the grant of 133,250 RSUs (base RSUs) with performance-based vesting conditions. This award is contingent upon the achievement of a 2017 revenue target and the number of shares that may be earned range between 50% and 200% of the base RSUs, dependent on the percentage of 2017 “managed revenues” (defined as the Company’s net product revenues, excluding net revenues attributable to Aldurazyme, and determined using fixed foreign currency exchange rates) achieved against the target managed revenues, with a threshold achievement level of 75% of target and a ceiling achievement level of 125% of target. RSUs with performance-based vesting conditions with similar performance conditions were granted in 2016 and 2015. The following table details the base RSUs granted, RSUs earned and expected to vest and the performance multiplier achieved and compensation expense recognized for the RSUs with performance-based vesting conditions for the years ended December 31, 2017, 2016 and 2015, respectively (dollars in thousands, except per RSU amounts): Grant Date Compensation Expense for the Years Ended December 31, Date of Grant Base RSUs Granted Fair Value per RSU Multiplier Achieved RSUs Earned 2017 2016 2015 March 2017 (1) 133,250 $ 87.42 103 % 131,651 $ 4,141 $ — $ — March 2016 (2) 130,310 $ 83.43 103 % 134,219 $ 3,928 $ 2,956 $ — March 2015 (2) 58,300 $ 108.36 111 % 64,713 $ 2,291 $ 2,342 $ 1,805 (1) Based on the Company’s performance against the 2017 revenue target, the Company expects its Compensation Committee to approve a multiplier of 103% and the participating executive officers to earn 131,651 RSUs, which will continue to vest ratably over a three-year service period. (2) The RSUs with performance-based vesting conditions granted in 2016 and 2015 were earned on the one year anniversary upon achievement of the respective performance target and vest ratably over a three-year service period. As of December 31, 2017, total unrecognized compensation expense of $12.4 million related to RSU awards with performance-vesting conditions is expected to be recognized over a weighted average period of 1.8 years. Compensation expense included in the Company’s Consolidated Statements of Operations for all stock-based compensation arrangements was as follows: Years Ended December 31, 2017 2016 2015 Cost of sales $ 10,636 $ 9,121 $ 6,836 Research and development 53,112 58,279 49,399 Selling, general and administrative 76,515 67,241 55,290 Total stock-based compensation expense $ 140,263 $ 134,641 $ 111,525 Stock-based compensation of $16.1 million, $11.4 million and $11.1 million was capitalized into inventory, for the years ended December 31, 2017, 2016 and 2015, respectively. Capitalized stock-based compensation is recognized as cost of sales when the related product is sold.

COMPREHENSIVE INCOME

COMPREHENSIVE INCOME	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
COMPREHENSIVE INCOME	(18) COMPREHENSIVE INCOME The following table summarizes amounts reclassified out of Accumulated Other Comprehensive Income (AOCI) and their effect on the Company’s Consolidated Statements of Operations for the years ended December 31, 2017 and 2016. Amount Reclassified from AOCI (Gain) Loss Years Ended December 31, Consolidated Statement of Details about AOCI Components 2017 2016 Operations Classification Gains (losses) on cash flow hedges: Forward foreign currency exchange contracts $ (5,377 ) $ 6,112 Net product revenues Forward foreign currency exchange contracts 264 4,161 Selling, general and administrative Total gain (loss) on cash flow hedges (5,113 ) 10,273 Gain (loss) on sale of available-for-sale debt securities 3,252 (115 ) Other income (expense) Less income tax effect of the above 1,191 42 Provision for (benefit from) income taxes $ (3,052 ) $ 10,116 Net loss The following table summarizes changes in the accumulated balances for each component of other comprehensive loss, including current period reclassifications out of AOCI and other amounts of current-period other comprehensive income, for the years ended December 31, 2017 and 2016. Year Ended Balance at December 31, 2017 Gains and Losses on Cash Flow Hedges Unrealized Gains on Available-for-Sale Debt Securities Foreign Currency Items Total AOCI balance at December 31, 2016 13,006 (178 ) (12 ) 12,816 Other comprehensive income (loss) before reclassifications (38,351 ) (755 ) 5 (39,101 ) Less: gain (loss) reclassified from AOCI (5,113 ) 3,252 (1,861 ) Tax effect — 1,463 — 1,463 Net current-period other comprehensive income (loss) (33,238 ) (2,544 ) 5 (35,777 ) AOCI balance at December 31, 2017 $ (20,232 ) $ (2,722 ) $ (7 ) $ (22,961 ) Year Ended Balance at December 31, 2016 Gains and Losses on Cash Flow Hedges Unrealized Gains on Available-for-Sale Debt Securities Foreign Currency Items Total AOCI balance at December 31, 2015 13,602 7,441 (10 ) 21,033 Other comprehensive income (loss) before reclassifications 9,677 (12,104 ) (2 ) (2,429 ) Less: net gain (loss) reclassified from AOCI 10,273 (115 ) 10,158 Tax effect — 4,370 — 4,370 Net current-period other comprehensive loss (596 ) (7,619 ) (2 ) (8,217 ) AOCI balance at December 31, 2016 13,006 (178 ) (12 ) 12,816

REVENUE AND CREDIT CONCENTRATIO

REVENUE AND CREDIT CONCENTRATIONS	12 Months Ended
	Dec. 31, 2017
Risks And Uncertainties [Abstract]
REVENUE AND CREDIT CONCENTRATIONS	(19) REVENUE AND CREDIT CONCENTRATIONS Net Product Revenue - The Company considers there to be revenue concentration risks for regions where net product revenue exceeds 10% of consolidated net product revenue. The concentration of the Company’s net product revenue within the regions below may have a material adverse effect on the Company’s revenue and results of operations if sales in the respective regions experience difficulties . The table below summarizes consolidated net product revenue concentrations based on patient location for Brineura, Firdapse, Kuvan, Naglazyme, and Vimizim, which are sold directly by the Company, and global sales of Aldurazyme, which is marketed by Genzyme. Genzyme is the Company ’ Years Ended December 31, 2017 2016 2015 Region: United States 39 % 37 % 39 % Europe 21 % 23 % 19 % Latin America 14 % 13 % 16 % Rest of world 19 % 19 % 15 % Total net product revenues marketed by the Company 93 % 92 % 89 % Aldurazyme net product revenues marketed by Genzyme 7 % 8 % 11 % Total net product revenue 100 % 100 % 100 % The following table illustrates the percentage of the Company’s consolidated net product revenues attributed to the Company’s largest customers. For the Years Ended December 31, 2017 2016 2015 Customer A 18 % 19 % 15 % Customer B 14 % 13 % 13 % Customer C 10 % 10 % — Customer D 7 % 8 % 11 % Customer E 7 % 6 % 10 % Total 56 % 56 % 49 % On a consolidated basis, the Company’s two largest customers accounted for 21% and 18% of the December 31, 2017 accounts receivable balance, respectively, compared to December 31, 2016 when the two largest customers accounted for 26% and 20% of the accounts receivable balance, respectively. As of December 31, 2017 and 2016, accounts receivable balance for Genzyme included $18.1 million and $30.7 million, respectively, of unbilled accounts receivable related to net incremental Aldurazyme product transfers to Genzyme. The Company does not require collateral from its customers, but does perform periodic credit evaluations of its customers’ financial condition and requires immediate payment in certain circumstances. The Company sells its products in countries that face economic volatility and weakness. Although the Company has historically collected receivables from customers in such countries, sustained weakness or further deterioration of the local economies and currencies may cause customers in those countries to be unable to pay for the Company’s products. The Company has not historically experienced a significant level of uncollected receivables and has received continued payments from its more aged accounts in these countries. The Company believes that the allowances for doubtful accounts related to these countries, if any, is adequate based on its analysis of the specific business circumstances and expectations of collection for each of the underlying accounts in these countries.

SEGMENT AND GEOGRAPHIC INFORMAT

SEGMENT AND GEOGRAPHIC INFORMATION	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
SEGMENT AND GEOGRAPHIC INFORMATION	(20) SEGMENT 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. Years Ended December 31, 2017 2016 2015 Net product revenues by product: Aldurazyme $ 89,959 $ 93,749 $ 97,912 Brineura 8,595 — — Firdapse 18,890 18,028 16,037 Kuvan 407,542 348,009 239,336 Naglazyme 332,208 296,537 303,090 Vimizim 413,251 354,058 228,147 Total net product revenues $ 1,270,445 $ 1,110,381 $ 884,522 The following table summarizes 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 based on the location of Genzyme’s headquarters. Although Genzyme sells Aldurazyme worldwide, the revenues earned by the Company based on Genzyme’s net sales are included in the U.S. region as the transactions are with Genzyme whose headquarters are located in the U.S. Years Ended December 31, 2017 2016 2015 Total revenues by geographic region: United States $ 588,243 $ 507,539 $ 444,075 Europe 301,487 252,633 171,216 Latin America 182,438 147,471 142,305 Rest of world 241,478 209,211 132,299 Total revenues $ 1,313,646 $ 1,116,854 $ 889,895 The following table summarizes non-monetary long-lived assets by geographic region. Non-monetary long-lived assets primarily consist of property, plant and equipment, intangible assets, deferred tax assets and goodwill. December 31, 2017 2016 Long-lived assets by geography: United States $ 1,183,791 $ 1,183,938 Europe 823,657 812,833 Rest of world 2,694 2,568 Total long-lived assets $ 2,010,142 $ 1,999,339

COLLABORATION AND LICENSE AGREE

COLLABORATION AND LICENSE AGREEMENTS	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
COLLABORATION AND LICENSE AGREEMENTS	(21) COLLABORATION AND LICENSE AGREEMENTS In July 2017, the Company executed a license agreement and a settlement agreement (the Sarepta Agreements) with Sarepta Therapeutics (Sarepta) that provide Sarepta with global exclusive rights to the Company’s Duchenne muscular dystrophy (DMD) patent estate for EXONDYS 51 and all future exon-skipping products. The Sarepta Agreements resolved the ongoing worldwide patent proceedings related to the use of EXONDYS 51 and all future exon-skipping products for the treatment of DMD. Pursuant to the Sarepta Agreements, Sarepta paid the Company a one-time upfront fee of $35.0 million, which was recognized as license revenue. Under the Sarepta Agreements, Sarepta may pay certain additional regulatory and commercial milestone fees for exons 51, 45, 53 and possibly on future exon-skipping products to the Company if certain development and sales milestones are achieved. Additionally, Sarepta will pay the Company royalties based on 5% of net sales in the U.S. through the end of 2023 and 8% of net sales in the EU and in other countries where certain of the Company’s patents exist through September 30, 2024. The Company retained the right to convert the license to a co-exclusive right in the event it decides to proceed with an exon-skipping therapy for DMD. The Company is engaged in R&D collaborations with various other entities. These provide for sponsorship of R&D by the Company and may also provide for exclusive royalty-bearing intellectual property licenses or rights of first negotiation regarding licenses to intellectual property development under the collaborations. Typically, these agreements can be terminated for cause by either party upon 90 days written notice. On October 6, 2015, the Company completed the sale of talazoparib to Medivation Inc. (Medivation) pursuant to an asset purchase agreement (the Medivation Asset Purchase Agreement). Pursuant to the Medivation Asset Purchase Agreement, Medivation paid the Company an upfront payment of $410.0 million upon the closing of the transaction. In addition, contingent upon the successful development and commercialization of talazoparib, In September 2016, Pfizer Inc. acquired Medivation, therefore obligations under the Medivation Asset Purchase Agreement transferred to Pfizer. In accordance with the Medivation Asset Purchase Agreement, Pfizer will pay the Company milestone payments of up to $160.0 million and mid-single digit percentage royalties on net sales of talazoparib. During the fourth quarter of 2015, the Company recognized a net gain of $369.5 million related to the sale of the talazoparib intangible assets. In October 2012, the Company licensed to Catalyst Pharmaceutical Partners, Inc., (Catalyst) the North American rights to develop and market Firdapse. In consideration of this licensing arrangement, the Company received from Catalyst a $5.0 million convertible promissory note. Under the terms of the note agreement, the Company received 6.7 million shares of Catalyst common stock upon the automatic conversion of the convertible promissory note on December 10, 2012. In exchange for the North American rights to Firdapse the Company may receive royalties of 7% to 10% on net product sales of Firdapse in North America. As of December 31, 2017, there were no amounts due from Catalyst for reimbursable development costs and the Company no longer held shares of Catalyst common stock. In September 2007, the Company licensed to Asubio Pharma Co., Ltd. (a subsidiary of Daiichi Sankyo) exclusive rights to data and intellectual property contained in the Kuvan new drug application. The Company receives royalties on net sales of the product in Japan.

COMPENSATION AGREEMENTS AND PLA

COMPENSATION AGREEMENTS AND PLANS	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
COMPENSATION AGREEMENTS AND PLANS	(22) COMPENSATION AGREEMENTS AND PLANS Employment Agreements The Company has entered into employment agreements with certain officers. Generally, these agreements can be terminated without cause by the Company upon prior written notice and payment of specified severance, or by the officer upon four weeks’ prior written notice to the Company. 401(k) Plan The Company sponsors the BioMarin Retirement Savings Plan (the 401(k) Plan). Most employees (Participants) are eligible to participate following the start of their employment, at the beginning of each calendar month. Participants may contribute to the 401(k) Plan up to the lesser of 100% of their current compensation or an amount up to a statutorily prescribed annual limit. The Company pays the direct expenses of the 401(k) Plan and matched 100% of each Participant’s contributions, up to a maximum of the lesser of 6% of the employee’s annual compensation or $14,000 per year ($16,000 per year effective January 1, 2018). The Company’s matching contribution vests over four years from employment commencement and was approximately $19.8 million, $16.0 million and $15.1 million for the years ended December 31, 2017, 2016 and 2015, respectively. Employer contributions not vested upon employee termination are forfeited. Deferred Compensation Plan In December 2005, the Company adopted the Deferred Compensation Plan. All of the investments held in the NQDC Plan are classified as trading securities and recorded at fair value with changes in the investments’ fair values recognized as earnings in the period they occur. Company stock issued and held by the NQDC Plan is accounted for similarly to treasury stock in that the value of the employer stock is determined on the date the restricted stock vests and the shares are issued into the NQDC Plan. The restricted stock issued into the NQDC Plan is recorded as stockholders’ equity and changes in the fair value of the corresponding liability are recognized in earnings as incurred. The corresponding liabilities for the NQDC Plan are included in Accounts Payable and Accrued Liabilities and Other Long-Term Liabilities in the Company’s Consolidated Balance Sheets. The corresponding assets for the NQDC Plan are included in Other Current Assets and Other Assets in the Company’s Consolidated Balance Sheets. As of December 31, 2017 and 2016, the fair value of Company stock held by the Deferred Compensation Plan, was $19.6 million and $19.4 million, respectively, which is included in current and non-current liabilities. The change in market value amounted to a loss of $1.4 million, a gain of $5.0 million and a gain of $2.5 million in the years 2017, 2016 and 2015, respectively. See Note 12 to these Consolidated Financial Statements for additional discussion regarding the fair value of the Deferred Compensation Plan assets and liabilities.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	(23) COMMITMENTS AND CONTINGENCIES Lease Commitments The Company leases office space and research, testing and manufacturing laboratory space in various facilities under operating agreements expiring at various dates through 2026. Certain of the leases provide for options by the Company to extend the lease for multiple five-year renewal periods and also provide for annual minimum increases in rent, usually based on a consumer price index or annual minimum increases. Minimum lease payments for future years are as follows: 2018 $ 9,697 2019 7,671 2020 5,996 2021 4,948 2022 3,961 Thereafter 5,851 Total $ 38,124 Rent expense for the years ended December 31, 2017, 2016 and 2015 was $11.4 million, $11.6 million and $9.3 million, respectively. Deferred rent accruals at December 31, 2017 totaled $2.3 million, of which $2.0 million was current. Deferred rent accruals at December 31, 2016 totaled $2.4 million, of which $2.0 million was current. Research and Development Funding and Technology Licenses The Company uses experts and laboratories at universities and other institutions to perform certain R&D activities. These amounts are included as R&D expense as services are provided. The Company has also licensed technology, for which it is required to pay royalties upon future sales, subject to certain annual minimums. Other Commitments In the normal course of business, the Company enters into various firm purchase commitments primarily related to active pharmaceutical ingredients and certain inventory related items. As of December 31, 2017, these commitments for the next five years were approximately $52.8 million. The amounts primarily related to active pharmaceutical ingredients represent minimum purchase requirements and post marketing commitments related to the Company’s approved products. Contingencies From time to time the Company is involved in legal actions arising in the normal course of its business. The most significant of these actions are described below. 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 and 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. Paragraph IV Notice s The Company received a paragraph IV notice letter, dated December 23, 2016, from Dr. Reddy’s Laboratories, Inc. and Dr. Reddy’s Laboratories, Ltd. (collectively, DRL), notifying the Company that DRL had filed an abbreviated new drug application (ANDA) seeking approval of a proposed generic version of Kuvan (sapropterin dihydrochloride) 100 mg oral powder prior to the expiration of the Company’s patents listed in the FDA's Approved Drug Products with Therapeutic Equivalence Evaluations (the Orange Book). The Company filed a lawsuit alleging patent infringement against DRL. In August 2017, the Company entered into a settlement agreement with DRL (the DRL Powder Settlement Agreement) that resolved the patent litigation with DRL in the U.S. related to Kuvan 100 mg oral powder. Under the terms of the DRL Powder Settlement Agreement, the Company granted DRL a non-exclusive license to its Kuvan-related patents to allow DRL to market a generic version of sapropterin dihydrochloride in oral powder form in 100 mg and 500 mg packet formulations in the U.S. for the indications approved for Kuvan beginning on October 1, 2020, or earlier under certain circumstances. The Company also received two separate paragraph IV notice letters, dated January 14, 2016 and January 22, 2015, from Par Pharmaceutical, Inc. (Par), notifying the Company that Par had filed an ANDA seeking approval of proposed generic versions of Kuvan 100 mg oral powder and Kuvan 100 mg oral tablets, respectively, prior to the expiration of the Company’s patents listed in the FDA’s Orange Book. The Company filed two lawsuits alleging patent infringement against Par (the lawsuit against Par pertaining to the proposed generic version of Kuvan 100 mg oral tablets was filed together with Merck & Cie), and the The Company also received a paragraph IV notice letter, dated October 3, 2014, from DRL notifying the Company that DRL had filed an ANDA seeking approval of a proposed generic version of Kuvan 100 mg oral tablets prior to the expiration of the Company’s patents listed in the FDA’s Orange Book. The Company, together with Merck & Cie, filed a lawsuit alleging patent infringement against DRL. In September 2015, the Company and Merck & Cie entered into a settlement agreement with DRL (the DRL Tablet Settlement Agreement) that resolved the patent litigation with DRL in the U.S. related to Kuvan 100 mg oral tablets. Under the terms of the DRL Tablet Settlement Agreement, the Company granted DRL a non-exclusive license to its Kuvan-related patents to allow DRL to market a generic version of sapropterin dihydrochloride 100 mg oral tablets in the U.S. for the indications approved for Kuvan beginning on October 1, 2020, or earlier under certain circumstances. Contingent Payments As of December 31, 2017, the Company is also subject to contingent payments totaling approximately $604.6 million upon achievement of development and regulatory activities and commercial sales and licensing milestones if they occur before certain dates in the future. Of this amount, $222.0 million (or € As of December 31, 2017, the Company has recorded $189.0 million of contingent acquisition consideration payable on its Consolidated Balance Sheets in Short-term and Long-term Contingent Acquisition Consideration Payable, of which $53.6 million is expected to be paid in the next twelve months.

BASIS OF PRESENTATION (Policies

BASIS OF PRESENTATION (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation These 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 for Annual Reports on Form 10-K and include the accounts of BioMarin and its wholly owned subsidiaries. All significant intercompany transactions have been eliminated. Management performed an evaluation of the Company’s activities through the date of filing of this Annual Report on Form 10-K, and has concluded that there are no subsequent events or transactions that occurred subsequent to the balance sheet date and prior to the filing this Annual Report on Form 10-K that would require recognition or disclosure in the Consolidated Financial Statements.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the dates of the financial statements, and the reported amounts of revenues and expenses during the reporting period. 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.
Cash, Cash Equivalents and Investments	Cash, Cash Equivalents and Investments The Company treats liquid investments with original maturities of three months or less when purchased as cash and cash equivalents. Cash and cash equivalents primarily consist of cash on deposit with banks, investments in money market funds and debt securities with original maturities of three months or less when purchased. The Company determines the appropriate classification of its investments in debt and equity securities at the time of purchase and reevaluates such designations at each balance sheet date. The Company classifies its debt and equity securities with original maturities greater than three months when purchased as either short-term or long-term investments based on each instrument’s underlying contractual maturity date and its availability for use in current operations. Available-for-sale debt securities are recorded at fair market value, with unrealized gains and losses included in Accumulated Other Comprehensive Income (Loss) on the Company’s Consolidated Balance Sheets, with the exception of unrealized losses believed to be other-than-temporary, if any, which are reported in Other Income (Expense) in the current period. Available-for-sale debt securities primarily consist of corporate securities, commercial paper, U.S. federal government agency securities and certificates of deposit.
Inventory	Inventory The Company values inventory at the lower of cost and net realizable value and determines the cost of inventory using the average-cost method. The Company analyzes its inventory levels quarterly and adjusts inventory to its net realizable value, if required, for obsolete, or has a cost basis in excess of its expected net realizable value or for quantities in excess of expected requirements. These adjustments are recognized as Cost of Sales in the Company’s Consolidated Statements of Operations. When future commercialization is considered probable and the future economic benefit is expected to be realized, based on management’s judgment, the Company capitalizes pre-launch inventory costs prior to regulatory approval. A number of factors are taken into consideration, including the current status in the regulatory approval process, pivotal clinical trial results for the underlying product candidate, results from meetings with the relevant regulatory authorities prior to the filing of regulatory applications, historical experience, as well as potential impediments to the approval process such as product safety or efficacy, commercialization and marketplace trends. As of December 31, 2017, the amount of pre-launch inventory on the Company’s Consolidated Balance Sheets was not significant.
Property, Plant And Equipment	Property, Plant and Equipment Property, plant and equipment are stated at cost net of accumulated depreciation. Depreciation is computed using the straight-line method over the related estimated useful lives as presented in the table below. Significant additions and improvements are capitalized, while repairs and maintenance are charged to expense as incurred. Depreciation of property, plant and equipment are included in Cost of Sales, Selling, General and Administrative and Research and Development, as appropriate, in the Consolidated Statements of Operations. Property and equipment purchased for specific R&D projects with no alternative uses are expensed as incurred and recorded to Research and Development in the Consolidated Statements of Operations. Leasehold improvements Shorter of life of asset or lease term Building and improvements 15 to 50 years Manufacturing and laboratory equipment 5 to 18 years Computer hardware and software 3 to 10 years Office furniture and equipment 5 to 10 years Vehicles 5 years Land improvements 5 to 10 years Land Not applicable Construction-in-progress Not applicable
Leases	Leases Certain of the Company’s operating lease agreements include scheduled rent escalations over the lease term, as well as tenant improvement allowances. Scheduled increases in rent expense are recognized on a straight-line basis over the lease term. The difference between rent expense and rent paid is recorded as deferred rent and included in Other Liabilities in the Consolidated Balance Sheets. The tenant improvement allowances and free rent periods are recognized as a reduction of rent expense over the lease term on a straight-line basis. Rent expense is recorded to Cost of Sales, Research and Development and/or Selling, General and Administrative, as appropriate, in the Consolidated Statements of Operations.
Goodwill and Intangible Assets	Goodwill and Intangible Assets The Company records goodwill in a business combination when the total consideration exceeds the fair value of the net tangible and identifiable intangible assets acquired. Intangible assets with indefinite useful lives are related to purchased in-process research and development (IPR&D) projects and are measured at their respective fair values as of the acquisition date. The Company does not amortize goodwill and intangible assets with indefinite useful lives. Intangible assets related to IPR&D projects are considered to be indefinite lived until the completion or abandonment of the associated R&D efforts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets are considered finite-lived and are amortized using the straight-line method based on their respective estimated useful lives at that point in time. The amortization of these intangible assets is included in Intangible Asset Amortization and Contingent Consideration in the Consolidated Statements of Operations.
Impairment	Impairment The Company reviews its goodwill and indefinite lived intangible assets for impairment annually in the fourth quarter, or more frequently as warranted by events or changes in circumstances which indicate that the carrying amount may not be recoverable. The Company qualitatively assesses goodwill and indefinite lived intangible assets to determine whether it is more likely than not that the fair value of the Company’s single reporting unit or other indefinite lived intangible asset is less than its carrying amount. If it is determined that the fair value is more likely than not less than its carrying value, a two-step impairment test will be performed. In the first step of the impairment test, the Company compares the carrying value of its single reporting unit or applicable asset to its fair value, which the Company estimates using a discounted cash flow analysis. If the carrying amount of its single reporting unit or asset exceeds its estimated fair value, the Company performs the second step, and determines the impairment loss, if any, as the excess of the carrying value of the goodwill or intangible asset over its fair value. Impairment charges that are not material are recorded to Intangible Asset Amortization and Contingent Consideration in the Consolidated Statements of Operations. See Note 7 to these Consolidated Financial Statements for the results of the Company’s 2017 qualitative assessment. Long-lived assets including property, plant and equipment and finite-lived intangible assets are reviewed for impairment whenever facts or circumstances whether internally or externally may suggest that the carrying value of an asset or asset group may not be recoverable. Should there be an indication of impairment, the Company tests for recoverability by comparing the estimated undiscounted future cash flows expected to result from the use of the asset or asset group and its eventual disposition to the carrying amount of the asset or asset group. Any excess of the carrying value of the asset or asset group over its estimated fair value is recognized as an impairment loss.
Revenue Recognition	Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred, the price to the buyer is fixed or determinable and collection from the customer is reasonably assured. Net Product Revenues —The Company recognizes revenues from product sales when title and risk of loss have passed to the customer, which typically occurs upon delivery. Product sales transactions are evidenced by customer purchase orders, customer contracts, invoices and/or the related shipping documents. Amounts collected from customers and remitted to governmental authorities, which primarily consists of value-added taxes related to product sales in foreign jurisdictions, are presented on a net basis in the Consolidated Statements of Operations, in that taxes billed to customers are not included as a component of net product revenues. In the U.S., the Company’s commercial products are generally sold to specialty pharmacies or end-users, such as hospitals, which act as retailers. Through December 31, 2015, the Company also sold Kuvan to Ares Trading S.A. (Merck Serono) at a price near its manufacturing cost, and Merck Serono resold the product to end users outside the U.S., Canada and Japan. The royalty earned from Kuvan product sold by Merck Serono in the EU was included as a component of Net Product Revenues in the period earned. Outside the U.S., the Company’s commercial products are sold to its authorized distributors or directly to government purchasers or hospitals, which act as the end-users. The Company receives a payment ranging from . See Note 4 to these Consolidated Financial Statements for further discussion on the Company’s adoption of Accounting Standards Update (ASU) No. 2014-09 (ASU 2014-09), Revenue from Contracts with Customers , as amended (commonly referred to as ASC Topic 606) on January 1, 2018. The Company records an allowance for government and other rebates is estimated based on products sold, customer mix, and program requirements. The Company evaluates its customer mix to estimate which sales will be subject to rebates and consider changes to government program guidelines that would impact the actual rebates and/or estimates of which sales qualify for such rebates. The Company updates its estimates and assumptions on a quarterly basis based on actual historical experience and records any necessary adjustments to its reserves. The Company records fees paid to distributors and cash discounts as a reduction of revenue. The Company records allowances for product returns, if appropriate, as a reduction of revenue at the time product sales are recorded. The Company relies on historical return rates to estimate returns. Several factors are considered in determining whether an allowance for product returns is required, including market exclusivity of the products based on their orphan drug status, the patient population, the customers’ limited return rights and the Company’s experience with returns. Because of the pricing of the Company’s commercial products, the limited number of patients and the customers’ limited return rights, most customers and retailers carry a limited inventory. Certain international customers, usually government entities, tend to purchase larger quantities of product less frequently. Although such buying patterns may result in revenue fluctuations from quarter to quarter, the Company has not experienced any increased product returns or risk of product returns related to such buying patterns. Genzyme’s contractual return rights for Aldurazyme are limited to defective product. Based on these factors and the fact that the Company has not experienced significant product returns to date, management has concluded that product returns will be minimal. In the future, if any of these factors and/or the history of product returns change, an allowance for product returns may be required. Royalty and Other Revenues— includes royalties on net sales of products with which the Company has no direct involvement, collaborative agreement revenues and rental income. Royalty revenue Revenue from non-refundable up-front license fees, such as under an obligation to supply product, is recognized as performance occurs and the Company’s obligations are completed or recognized up-front upon agreement execution if there are no continuing involvement performance obligations. Revenue associated with substantive at-risk milestones is recognized based upon the achievement of the milestones set forth in the respective agreements. Advance payments received in excess of amounts earned are classified as deferred revenue on the Company’s Consolidated Balance Sheets .
Research and Development	Research and Development R&D costs are generally expensed as incurred. These expenses include contract R&D provided by third parties, most product manufacturing prior to regulatory approval, materials and supplies, clinical and regulatory costs, and personnel costs including salaries, benefits and stock-based compensation. In instances where the Company enters into agreements with third parties for R&D activities, costs are expensed upon the earlier of when non-refundable amounts are due or as services are performed unless there is an alternative future use of the funds in other R&D projects. Amounts due under such arrangements may be either fixed fee or fee for service and may include upfront payments, monthly payments and payments upon the completion of milestones or receipt of deliverables.
Convertible Debt	Convertible Debt For non-conventional convertible debt that may be settled entirely or partially in cash, the Company separately accounts for the liability and equity components by allocating the proceeds from issuance between the liability component and the embedded conversion option, or equity component. The value of the equity component is calculated by first measuring the fair value of the liability component, using the interest rate of a similar liability that does not have a conversion feature, as of the issuance date. The difference between the proceeds from the convertible debt issuance and the amount measured as the liability component is recorded as the equity component with a corresponding discount recorded on the debt. The liability component is presented net of any discounts and issuance costs. For conventional convertible debt that may only be settled with common shares, the Company accounts for the debt net of any discounts or issuance costs on the Consolidated Balance Sheet. The Company recognizes discount accretion and debt issuance cost amortization using the effective interest method as part of Interest Expense in the Consolidated Statements of Operations.
Net Loss Per Common Share	Net Loss Per Common Share Basic net loss per share is calculated by dividing net loss by the weighted average shares of common stock outstanding during the period. Diluted net loss per share reflects the potential dilution that would occur if securities or other contracts to issue common stock were exercised or converted into common stock; however, potential common equivalent shares are excluded if their effect is anti-dilutive. See Note 14 to these Consolidated Financial Statements for further details.
Stock-Based Compensation	Stock-Based Compensation The Company has stock-based compensation plans, including an Employee Stock Purchase Plan (ESPP), under which various types of equity-based awards are granted or available to employees, including restricted stock units (RSUs) with both performance and service-based vesting conditions and stock options. Stock-based compensation expense is recognized on a straight-line basis over the requisite service period for each award and is classified as Cost of Sales, Research and Development or Selling, General and Administrative, as appropriate, in the Consolidated Statements of Operations. The Company accounts for forfeitures as they occur. The fair value of each stock option award and the Company’s ESPP awards are estimated on the date of grant using the Black-Scholes valuation model and the following assumptions: expected life of a stock option, expected volatility, risk-free interest rate and expected dividend yield. The dividend yield reflects that the Company has not paid any cash dividends since inception and does not intend to pay any cash dividends in the foreseeable future. The expected life of stock options is based on observed historical exercise patterns. Groups of employees that have similar historical exercise patterns were considered separately for valuation purposes. The Company has identified two groups, executive and non-executive employees, with distinctly different exercise patterns. The executive employee group has a history of holding stock options for longer periods than non-executive employees. The determination of the fair value of stock-based payment awards using an option-pricing model is affected by the Company’s stock price and may use assumptions regarding a number of complex and subjective variables. The fair value of RSUs with service-based vesting conditions and RSUs with performance conditions is determined to be the fair market value of the Company’s underlying common stock on the date of grant. The stock-based compensation for RSUs with service-based vesting is recognized ratably over the period during which the vesting restrictions lapse. Stock-based compensation for RSUs with performance conditions is recognized ratably over the service period beginning in the period the Company determines it is probable that the performance condition will be achieved. See Note 17 to these Consolidated Financial Statements for further information.
Income Taxes	Income Taxes The Company calculates and provides for income taxes in each of the tax jurisdictions in which it operates. Deferred tax assets and liabilities, measured using enacted tax rates, are recognized for the future tax consequences of temporary differences between the tax and financial statement basis of assets and liabilities. A valuation allowance reduces the deferred tax assets to the amount that is more likely than not to be realized. The Company establishes liabilities or reduces assets for uncertain tax positions when the Company believes certain tax positions are not more likely than not of being sustained if challenged. Each quarter, the Company evaluates these uncertain tax positions and adjusts the related tax assets and liabilities in light of changing facts and circumstances. The Company uses financial projections to support its net deferred tax assets, which contain significant assumptions and estimates of future operations. If such assumptions were to differ significantly, it may have a material impact on the Company’s ability to realize its deferred tax assets. At the end of each period, the Company will reassess the ability to realize its deferred tax benefits. If it is more likely than not that the Company would not realize the deferred tax benefits, a valuation allowance may need to be established against all or a portion of the deferred tax assets, which will result in a charge to tax expense.
Foreign Currency	Foreign Currency For the Company and its subsidiaries, the functional currency has been determined to be the U.S. dollar. Assets and liabilities denominated in foreign currency are remeasured at period-end exchange rates for monetary assets. Non-monetary assets and liabilities denominated in foreign currencies are remeasured at historical rates. Foreign currency transaction gains and losses resulting from remeasurement are recognized in Selling, General and Administrative in the Consolidated Statements of Operations.
Derivatives and Hedging Activities	Derivatives and Hedging Activities The Company accounts for its derivative instruments as either assets or liabilities on the balance sheet and measures them at fair value. Derivatives that are not designated as hedging instruments are adjusted to fair value through earnings in Selling, General and Administrative in the Consolidated Statements of Operations. For derivative instruments that hedge the exposure to variability in expected future cash flows that are designated as cash flow hedges, the effective portion of the gain or loss is reported as a component of Accumulated Other Comprehensive Income (Loss) in shareholders’ equity and reclassified to earnings in the same period or periods during which the hedged transaction affects earnings. The ineffective portion of the gain or loss on the derivative instrument, if any, is recognized in earnings in the current period. To receive hedge accounting treatment, cash flow hedges must be highly effective in offsetting changes to expected future cash flows on hedged transactions. The Company does not hold or issue derivative instruments for trading or speculative purposes. See Note 11 to these Consolidated Financial Statements for further information.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and non-financials assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. The Company defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities that are required to be recorded at fair value, the Company considers the principal or most advantageous market in which the Company would transact and the market-based risk measurements or assumptions that that market participants would use to price the asset or liability, such as risks inherent in valuation techniques, transfer restrictions and credit risk. When estimating fair value, depending on the nature and complexity of the asset or liability, the Company may use the following techniques: • Income approach, which is based on the present value of a future stream of net cash flows • Market approach, which is based on market prices and other information from market transactions involving identical or comparable assets or liabilities. The Company’s fair value methodologies depend on the following types of inputs: • Quoted prices for identical assets or liabilities in active markets (Level 1 inputs) • Quoted prices for similar assets or liabilities in active markets, or quoted prices for identical or similar assets or liabilities that are not active, or inputs other than quoted process that are directly or indirectly observable, or inputs that are derived principally from, or corroborated by, observable market data by correlation or other means (Level 2 inputs) • Unobservable inputs that reflect estimates and assumptions (Level 3 inputs) See Note 12 to these Consolidated Financial Statements for further information.
Segment Information	Segment Information The Company currently operates in one business segment focused on the development and commercialization of innovative therapies for people with serious and life threatening rare diseases and medical conditions. A single management team reports to the chief operating decision maker who comprehensively manages the entire business. All products are included in one segment because the majority of the Company’s products have similar economic and other characteristics, including the nature of the products and production processes, type of customers, distribution methods and regulatory environment. The Company is not organized by market and is managed and operated as one business. The Company does not operate any separate lines of business or separate business entities with respect to its products. Accordingly, the Company does not accumulate discrete financial information with respect to separate products, other than revenues, and does not have separately reportable segments.
Acquisitions	Acquisitions Acquisitions of businesses are accounted for using the acquisition method of accounting. The Company allocates the purchase price of acquired businesses to the tangible and intangible assets acquired and liabilities assumed based upon their estimated fair values on the acquisition date. The purchase price allocation process requires management to make significant estimates and assumptions, especially at the acquisition date with respect to intangible assets and IPR&D. In connection with the purchase price allocations for acquisitions, the Company estimates the fair value of contingent acquisition consideration payments utilizing a probability-based income approach inclusive of an estimated discount rate. Each reporting period thereafter, the Company revalues these obligations and records increases or decreases in their fair value as adjustments to Intangible Asset Amortization and Contingent Consideration in the Consolidated Statements of Operations. Changes in the fair value of the contingent acquisition consideration payable can result from changes to one or multiple inputs including the estimated probability with respect to regulatory approval, changes in the assumed timing of when milestones are likely to be achieved and changes in assumed discount periods and rates.

SUMMARY OF SIGNIFICANT ACCOUN33

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule Of Property, Plant And Equipment Estimated Useful Lives	Leasehold improvements Shorter of life of asset or lease term Building and improvements 15 to 50 years Manufacturing and laboratory equipment 5 to 18 years Computer hardware and software 3 to 10 years Office furniture and equipment 5 to 10 years Vehicles 5 years Land improvements 5 to 10 years Land Not applicable Construction-in-progress Not applicable

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed	The following table presents the final allocation of the purchase consideration for the Merck PKU Business acquisition, including the contingent acquisition consideration payable based on the acquisition date fair value. The allocation of the purchase price below reflects an inventory adjustment in the second quarter of 2016. Cash payments $ 374,545 Estimated fair value of contingent acquisition consideration payable 138,974 Total consideration $ 513,519 Kuvan intangible assets $ 172,961 Pegvaliase IPR&D 326,359 Inventory 14,199 Total identifiable assets acquired $ 513,519

INVESTMENTS (Tables)

INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Investments Schedule [Abstract]
Amortized Cost, Gross Unrealized Holding Gain or Loss, and Fair Value of Available For Sale Debt Security by Major Security type	The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s available-for-sale debt securities by major security type at December 31, 2017 and 2016 are summarized in the tables below: Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value at December 31, 2017 Corporate debt securities $ 707,652 $ 150 $ (2,553 ) $ 705,249 Commercial paper 24,566 — — 24,566 U.S. government agency securities 472,593 — (1,975 ) 470,618 Foreign and other 25,540 150 (64 ) 25,626 Total $ 1,230,351 $ 300 $ (4,592 ) $ 1,226,059 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value at December 31, 2016 Certificates of deposit $ 2,800 $ — $ — $ 2,800 Corporate debt securities 641,670 329 (2,282 ) 639,717 Commercial paper 16,075 — — 16,075 U.S. government agency securities 310,635 37 (747 ) 309,925 Foreign and other 48 86 — 134 Total $ 971,228 $ 452 $ (3,029 ) $ 968,651
Fair Values of Available-For-Sale Securities by Contractual Maturity	The fair values of available-for-sale securities by contractual maturity were as follows: December 31, 2017 2016 Maturing in one year or less $ 840,274 $ 395,940 Maturing after one year through five years 385,785 572,711 Total $ 1,226,059 $ 968,651

INTANGIBLE ASSETS (Tables)

INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	Intangible assets consisted of the following: December 31, 2017 2016 Intangible assets: Finite-lived intangible assets $ 303,298 $ 305,122 Indefinite-lived intangible assets 326,359 332,199 Gross intangible assets: 629,657 637,321 Less: Accumulated amortization (112,147 ) (83,541 ) Net carrying value $ 517,510 $ 553,780
Schedule of Net-Book-Value and Estimated Remaining Life of Finite-Lived Intangible Assets	The following table summarizes the net-book-value and estimated remaining life of the Company’s finite-lived intangible assets as of December 31, 2017: Net Balance at December 31, 2017 Average Remaining Life Repurchased royalty rights $ 39,938 5.9 years Acquired intellectual property 149,229 7.2 years License payments for marketing approvals 1,357 4.4 years In-place and above market tenant leases 627 0.7 - 5.6 years Total $ 191,151
Schedule of Future Amortization Expense of Finite-Lived Intangible Assets	As of December 31, 2017, the estimated future amortization expense associated with the Company’s finite-lived intangible assets for each of the five succeeding fiscal years was as follows: Fiscal Year Amount 2018 $ 30,400 2019 30,086 2020 27,605 2021 26,681 2022 26,657 Thereafter 49,722 $ 191,151
Schedule of Indefinite-Lived Intangible Assets	Indefinite-lived intangible assets consisted of the following: December 31, 2017 2016 In-Process Research and Development: Pegvaliase $ 326,359 $ 326,359 Other acquired pre-clinical compounds — 5,840 Net carrying value $ 326,359 $ 332,199

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Schedule of Property Plant and Equipment Net	Property, plant and equipment, net, consisted of the following: December 31, 2017 2016 Building and improvements $ 663,347 $ 510,805 Manufacturing and laboratory equipment 294,521 242,899 Computer hardware and software 144,268 129,506 Leasehold improvements 42,572 44,184 Furniture and equipment 31,515 27,229 Land improvements 5,331 4,881 Land 62,369 55,412 Construction-in-progress 59,511 126,446 1,303,434 1,141,362 Less: Accumulated depreciation $ (406,734 ) (342,594 ) Total property, plant and equipment, net $ 896,700 $ 798,768

INVENTORY (Tables)

INVENTORY (Tables)	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Schedule Of Inventory	Inventory consisted of the following: December 31, 2017 2016 Raw materials $ 49,877 $ 51,250 Work-in-process 234,674 167,788 Finished goods 191,224 136,088 Total inventory $ 475,775 $ 355,126

SUPPLEMENTAL BALANCE SHEET IN39

SUPPLEMENTAL BALANCE SHEET INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities consisted of the following: December 31, 2017 2016 Accounts payable and accrued operating expenses $ 166,616 $ 191,353 Accrued compensation expense 140,781 109,038 Accrued rebates payable 36,472 34,737 Accrued royalties payable 18,820 15,151 Value added taxes payable 9,740 7,848 Forward foreign currency exchange contracts 14,464 5,201 Accrued income taxes 5,528 — Other 9,500 7,177 Total accounts payable and accrued liabilities $ 401,921 $ 370,505
Schedule of Estimated Accrued Rebates and Reserve for Cash Discounts	The roll forward of significant estimated accrued rebates and reserve for cash discounts for the years ended December 31, 2017, 2016 and 2015 were as follows: Balance at Beginning of Period Provision for Current Period Sales Provision/ (Reversals) for Prior Period Sales Actual Charges Related to Current Period Sales Actual Charges Related to Prior Period Sales Balance at End of Period Year ended December 31, 2017: Accrued rebates $ 34,737 $ 56,282 $ (3,686 ) $ (31,714 ) $ (19,147 ) $ 36,472 Reserve for cash discounts 888 10,730 (58 ) (9,601 ) (904 ) 1,055 Year ended December 31, 2016: Accrued rebates $ 32,553 $ 44,347 $ (5,205 ) $ (23,879 ) $ (13,079 ) $ 34,737 Reserve for cash discounts 831 8,889 (22 ) (8,160 ) (650 ) 888 Year ended December 31, 2015: Accrued rebates $ 14,859 $ 45,356 $ (1,245 ) $ (18,421 ) $ (7,996 ) $ 32,553 Reserve for cash discounts 688 7,402 — (6,722 ) (537 ) 831

DERIVATIVE INSTRUMENTS AND HE40

DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative [Line Items]
Fair Value Carrying Amount of Derivative Instruments	The fair value carrying amounts of the Company’s derivative instruments were as follows: Asset Derivatives Liability Derivatives December 31, 2017 December 31, 2017 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments: Forward foreign currency exchange contracts Other current assets $ 4,015 Accounts payable & accrued liabilities $ 14,420 Forward foreign currency exchange contracts Other assets 4,973 Other long- term liabilities 12,686 Total $ 8,988 $ 27,106 Derivatives not designated as hedging instruments: Forward foreign currency exchange contracts Other current assets $ 675 Accounts payable & accrued liabilities $ 44 Total 675 44 Total value of derivative contracts $ 9,663 $ 27,150 Asset Derivatives Liability Derivatives December 31, 2016 December 31, 2016 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments: Forward foreign currency exchange contracts Other current assets $ 13,048 Accounts payable & accrued liabilities $ 5,176 Forward foreign currency exchange contracts Other assets 8,194 Other long- term liabilities 2,342 Total $ 21,242 $ 7,518 Derivatives not designated as hedging instruments: Forward foreign currency exchange contracts Other current assets $ 964 Accounts payable & accrued liabilities $ 25 Total 964 25 Total value of derivative contracts $ 22,206 $ 7,543
Effect of Derivative Instruments	The effect of the Company’s derivative instruments on the Consolidated Financial Statements for the years ended December 31, 2017, 2016 and 2015 was as follows: Years Ended December 31, 2017 2016 2015 Derivatives Designated as Hedging Instruments: Net gain (loss) recognized in accumulated other comprehensive loss (1) $ (38,351 ) $ 9,677 $ 17,300 Net gain (loss) reclassified from accumulated other comprehensive income (loss) into earnings (2) (5,113 ) 6,529 19,604 Net gain (loss) recognized in net loss (3) 2,576 5,070 (727 ) Derivatives Not Designated as Hedging Instruments: Net gain (loss) recognized in net loss (4) $ 8,255 $ (8,687 ) $ 4,493 (1) Net change in the fair value of the effective portion classified as accumulated other comprehensive income (loss). (2) Effective portion classified as Net Product Revenues and SG&A expense. (3) Ineffective portion and amount excluded from effectiveness testing classified as SG&A expense. (4) Classified as SG&A expense.
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Summary of Designated Forward Foreign Currency Exchange Contracts Outstanding	The following table summarizes the Company ’ Aggregate Notional Number of Amount in Foreign Exchange Contracts Contracts Foreign Currency Maturity Brazilian Reais – Sell 6 160.0 May 2018 Canadian Dollars – Sell 24 27.2 Jan. 2018 - Dec. 2018 Colombian Pesos – Sell 12 93,000.0 Jan. 2018 - Dec. 2018 Euros – Purchase 80 122.2 Jan. 2018 - Dec. 2020 Euros – Sell 289 373.5 Jan. 2018 - Dec. 2020 Total 411
Not Designated as Hedging Instrument
Derivative [Line Items]
Summary of Designated Forward Foreign Currency Exchange Contracts Outstanding	The following table summarizes the Company ’ Aggregate Notional Number of Amount in Foreign Exchange Contracts Contracts Foreign Currency Maturity British Pounds – Sell 1 5.0 January 2018 Euros – Purchase 4 93.5 January 2018 Total 5

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities	The tables below present the fair value of these financial assets and liabilities determined using the following input levels. Fair Value Measurements at December 31, 2017 Quoted Price in Active Markets For Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets: Cash equivalents (including available-for-sale debt securities): Money market instruments — 215,441 — 215,441 Corporate debt securities — 3,096 — 3,096 Commercial paper — 2,751 — 2,751 U.S. government agency securities — 35,497 — 35,497 Foreign and other — 990 — 990 Total cash and cash equivalents — 257,775 — 257,775 Available-for-sale debt securities: Short-term: Corporate debt securities — 406,188 — 406,188 Commercial paper — 21,815 — 21,815 U.S. government agency securities — 345,501 — 345,501 Foreign and other — 24,436 — 24,436 Long-term: Corporate debt securities — 295,965 — 295,965 U.S. government agency securities — 89,620 — 89,620 Foreign and other — 200 — 200 Total available-for-sale debt securities — 1,183,725 — 1,183,725 Other Current Assets: NQDC Plan assets — 967 — 967 Forward foreign currency exchange contract (1) — 4,690 — 4,690 Restricted investments (2) — 15,647 — 15,647 Total other current assets — 21,304 — 21,304 Other Assets: NQDC Plan assets — 11,859 — 11,859 Forward foreign currency exchange contract (1) — 4,973 — 4,973 Total other assets — 16,832 — 16,832 Total assets $ — $ 1,479,636 $ — $ 1,479,636 Liabilities: Current Liabilities: NQDC Plan liability $ 1,356 $ 967 $ — $ 2,323 Forward foreign currency exchange contract (1) — 14,464 — 14,464 Contingent acquisition consideration payable — — 53,648 53,648 Total current liabilities 1,356 15,431 53,648 70,435 Other long-term liabilities: NQDC Plan liability 18,272 11,859 — 30,131 Forward foreign currency exchange contract (1) — 12,686 — 12,686 Contingent acquisition consideration payable — — 135,318 135,318 Total other long-term liabilities 18,272 24,545 135,318 178,135 Total liabilities $ 19,628 $ 39,976 $ 188,966 $ 248,570 Fair Value Measurements at December 31, 2016 Quoted Price in Active Markets For Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets: Cash equivalents (including available-for-sale debt securities): Money market instruments — 235,571 — 235,571 Corporate debt securities — 8,593 — 8,593 U.S. government agency securities — 6,000 — 6,000 Total cash and cash equivalents — 250,164 — 250,164 Available-for-sale debt securities: Short-term: Certificates of deposit — 2,800 — 2,800 Corporate debt securities — 193,974 — 193,974 Commercial paper — 16,075 — 16,075 U.S. government agency securities — 168,498 — 168,498 Long-term: Corporate debt securities — 437,150 — 437,150 U.S. government agency securities — 135,427 — 135,427 Foreign and other — 134 — 134 Total available-for-sale debt securities — 954,058 — 954,058 Other Current Assets: Nonqualified Deferred Compensation Plan assets — 163 — 163 Forward foreign currency exchange contract (1) — 14,012 — 14,012 Restricted investments (2) — 3,754 — 3,754 Total other current assets — 17,929 — 17,929 Other Assets: Nonqualified Deferred Compensation Plan assets — 9,121 — 9,121 Forward foreign currency exchange contract (1) — 8,194 — 8,194 Strategic investment (3) 4,064 — — 4,064 Total other assets 4,064 17,315 — 21,379 Total assets $ 4,064 $ 1,239,466 $ — $ 1,243,530 Liabilities: Current Liabilities: Nonqualified Deferred Compensation Plan liability $ 2,073 $ 163 $ — $ 2,236 Forward foreign currency exchange contract (1) — 5,201 — 5,201 Contingent acquisition consideration payable — — 46,327 46,327 Total current liabilities 2,073 5,364 46,327 53,764 Other long-term liabilities: Nonqualified Deferred Compensation Plan liability 17,303 9,121 — 26,424 Forward foreign currency exchange contract (1) — 2,342 — 2,342 Contingent acquisition consideration payable — — 115,310 115,310 Total other long-term liabilities 17,303 11,463 115,310 144,076 Total liabilities $ 19,376 $ 16,827 $ 161,637 $ 197,840 (1) See Note 11 to these Consolidated Financial Statements for further information regarding the derivative instruments. (2) The restricted investments as of December 31, 2017 and 2016 secure the Company’s irrevocable standby letter of credit obtained in connection with certain commercial agreements. (3) The Company had investments in marketable equity securities measured using quoted prices in an active market that are considered strategic investments and included in Other Assets on the Company’s Balance Sheets. As of December 31, 2017, all holdings in the Company’s strategic investments have been liquidated.
Liabilities Measured at Fair Value Using Level 3 Inputs	Contingent acquisition consideration payable at December 31, 2016 $ 161,637 Milestone payments to former Huxley Pharmaceuticals, Inc. shareholders (3,500 ) Reversal of contingent liability related to revised estimate of Firdapse FDA acceptance and approval milestones (4,245 ) Changes in the fair value of other contingent acquisition consideration payable 14,587 Foreign exchange remeasurement of Euro denominated contingent acquisition consideration payable 20,487 Contingent acquisition consideration payable at December 31, 2017 $ 188,966

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Summary of Convertible Debt	The following table summarizes information regarding the Company’s convertible debt at December 31: 2017 2016 Convertible Notes due 2017 $ — $ 22,503 Unamortized deferred offering costs — (25 ) Convertible Notes due 2017, net — 22,478 Convertible Notes due 2018 374,980 374,980 Unamortized discount (12,488 ) (27,566 ) Unamortized deferred offering costs (1,543 ) (3,484 ) Convertible Notes due 2018, net 360,949 343,930 Convertible Notes due 2020 374,993 374,993 Unamortized discount (40,287 ) (53,239 ) Unamortized deferred offering costs (3,631 ) (4,923 ) Convertible Notes due 2020, net 331,075 316,831 Convertible Notes due in 2024 495,000 — Unamortized discount (9,355 ) — Unamortized deferred offering costs (3,199 ) — Convertible Notes due in 2024, net 482,446 — Total convertible debt, net $ 1,174,470 $ 683,239 Fair value of fixed rate convertible debt Convertible Notes due in 2017 (1) $ — $ 90,977 Convertible Notes due in 2018 (1) 403,955 423,202 Convertible Notes due in 2020 (1) 446,470 442,754 Convertible Notes due in 2024 (1) 493,894 — Total $ 1,344,319 $ 956,933 (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.
Summary of Interest Expense on Debt	Interest expense on the Company’s debt consisted of the following: Years Ended December 31, 2017 2016 2015 Coupon interest $ 10,407 $ 9,555 $ 9,750 Amortization of debt issuance costs 3,725 3,367 3,294 Accretion of discount on convertible notes 28,575 26,577 25,200 Total interest expense on convertible debt $ 42,707 $ 39,499 $ 38,244

NET LOSS PER COMMON SHARE (Tabl

NET LOSS PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings per Common Share	The following table sets forth the computation of basic and diluted earnings per common share (in thousands of common shares): Years Ended December 31, 2017 2016 2015 Numerator: Net loss, basic $ (117,042 ) $ (630,210 ) $ (171,799 ) Less: gain on common stock held by the NQDC — (3,184 ) — Net loss, diluted (117,042 ) (633,394 ) (171,799 ) Denominator: Weighted-average common shares outstanding, basic 174,427 165,985 160,025 Effect of dilutive securities: Common stock held by the NQDC — 234 — Weighted-average common shares outstanding, diluted 174,427 166,219 160,025 Net loss per common share, basic $ (0.67 ) $ (3.80 ) $ (1.07 ) Net loss per common share, diluted $ (0.67 ) $ (3.81 ) $ (1.07 )
Schedule Of Anti-Dilutive Common Stock Excluded From Computation of Basic and Diluted Net Loss Per Share	The table below presents potential shares of common stock that were excluded from the computation of basic and diluted earnings per common share as they were anti-dilutive using the if-converted or treasury stock method (in thousands): Years Ended December 31, 2017 2016 2015 Options to purchase common stock 8,108 8,856 10,323 Common stock issuable under the 2017 Notes — 1,105 1,544 Common stock issuable under the 2018 Notes 3,983 3,983 3,983 Common stock issuable under the 2020 Notes 3,983 3,983 3,983 Common stock issuable under the 2024 Notes 3,970 — — Unvested restricted stock units 2,911 2,618 1,743 Common stock potentially issuable for ESPP purchases 436 404 312 Common stock held by the NQDC 220 — 243 Total number of potentially issuable shares 23,611 20,949 22,131

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Provision for (Benefit from) Income Taxes Based on Loss Before Income Taxes	The provision for (benefit from) income taxes is based on loss before income taxes as follows: Years Ended December 31, 2017 2016 2015 U.S. Source $ (19,461 ) $ 10,696 $ 182,215 Non-U.S. Source (16,414 ) (841,746 ) (336,939 ) Loss before income taxes $ (35,875 ) $ (831,050 ) $ (154,724 )
Schedule of Components of Provision for (Benefit From) Income Taxes	The U.S. and foreign components of the provision for (benefit from) income taxes are as follows: Years Ended December 31, 2017 2016 2015 Provision for current income tax expense: Federal $ 29,848 $ 22,239 $ 84,743 State and local 2,880 1,418 5,323 Foreign 3,975 3,557 3,836 36,703 27,214 93,902 Provision for (benefit from) deferred income tax expense: Federal 12,446 (78,428 ) (17,741 ) State and local 32,336 (6,012 ) (8,770 ) Foreign (318 ) (143,614 ) (50,316 ) 44,464 (228,054 ) (76,827 ) Provision for (benefit from) income taxes $ 81,167 $ (200,840 ) $ 17,075
Schedule of Reconciliation of Statutory Federal Income Tax Rate to Company's Effective Income Tax Rate	The following is a reconciliation of the statutory federal income tax rate to the Company’s effective income tax rate expressed as a percentage of loss before income taxes: Years Ended December 31, 2017 2016 2015 Federal statutory income tax rate 35.0 % 35.0 % 35.0 % State and local taxes (20.3 )% 0.4 % (2.2 )% Orphan Drug & General Business Credit 93.9 % 7.5 % 34.8 % Stock compensation expense 19.1 % 4.6 % (2.8 )% Changes in the fair value of contingent acquisition consideration payable (3.1 )% 0.9 % 0.2 % Subpart F income (84.1 )% — % (8.4 )% Foreign tax rate differential (26.2 )% (18.6 )% (46.2 )% Section 162(m) limitation (26.5 )% (5.4 )% (1.3 )% Tax Cuts and Jobs Act of 2017 (118.0 )% — % — % Other 1.9 % 0.3 % (1.6 )% Valuation allowance/deferred benefit (97.9 )% (0.5 )% (18.5 )% Effective income tax rate (226.2 )% 24.2 % (11.0 )%
Schedule of Components of Net Deferred Tax Assets	The significant components of the Company’s net deferred tax assets are as follows: December 31, 2017 2016 Net deferred tax assets: Net operating loss carryforwards $ 48,374 $ 49,787 Tax credit carryforwards 384,381 352,535 Accrued expenses, reserves, and prepaids 54,565 77,904 Intangible assets 17,556 26,751 Stock-based compensation 31,371 47,713 Inventory 13,206 15,581 Impairment 2,609 5,017 Other 2,358 1,519 Valuation allowance (111,001 ) (73,037 ) Total deferred tax assets 443,419 503,770 Joint venture basis difference (1,229 ) (1,714 ) Acquired intangibles (3,332 ) (8,773 ) Convertible notes discount (10,100 ) (24,394 ) Property, plant and equipment (29,663 ) (22,103 ) Total deferred tax liabilities (44,324 ) (56,984 ) Net deferred tax assets $ 399,095 $ 446,786
Summary of Expiration of not Utilized Net Operating Loss and Tax Credit Carryforwards	As of December 31, 2017, the Company had the following net operating loss and tax credit carryforwards, which if not utilized, will expire as follows (dollars in thousands): Type Amount Year Federal net operating loss carryforwards $ 15,554 2028 – 2033 Federal R&D and orphan drug credit carryforwards $ 403,828 2030 – 2037 State net operating loss carryforwards $ 108,133 2019 – 2036 Dutch net operating loss carryforwards $ 145,150 2020 – 2025
Schedule of Reconciliation of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2017 and 2016 is as follows: December 31, 2017 2016 Balance at beginning of period $ 103,210 $ 86,731 Additions based on tax positions related to the current year 11,042 15,982 (Deletions) Additions for tax positions of prior years (766 ) 497 Balance at end of period $ 113,486 $ 103,210

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	Stock Options The following table summarizes activity under the Company’s stock option plans, including the 2012 and 2014 Inducement Plans and those suspended upon the adoption of the 2017 Share Incentive Plan, for the year ended December 31, 2017. All option grants presented in the table had exercise prices not less than the fair value of the underlying common stock on the grant date: Shares Weighted Average Exercise Price Weighted Average Remaining Years Aggregate Intrinsic Value (1) Options outstanding as of December 31, 2016 8,856,208 $ 51.13 5.4 $ 304,356 Granted 801,170 $ 87.74 Exercised (1,367,307 ) $ 34.96 Expired and forfeited (182,090 ) $ 92.98 Options outstanding as of December 31, 2017 8,107,981 $ 56.53 5.1 $ 281,141 Options unvested at December 31, 2017 1,462,941 $ 88.19 8.5 $ 6,313 Exercisable at December 31, 2017 6,645,032 $ 49.56 4.3 $ 274,828 (1) The aggregate intrinsic value for outstanding options is calculated as the difference between the exercise price of the underlying awards and the quoted price of the Company’s common stock on the Nasdaq Global Select Market as of the last trading day for the respective year. The aggregate intrinsic value of options outstanding and exercisable includes options with an exercise price below $89.17, the closing price of the Company’s common stock on the Nasdaq Global Select Market on December 29, 2017, the last trading day of the year.
Stock Option Valuation Assumptions	The assumptions used to estimate the per share fair value of stock options granted during the periods presented were as follows: Years Ended December 31, 2017 2016 2015 Expected volatility 38 – 40% 36 – 44% 36 – 45% Dividend yield 0.00% 0.00% 0.00% Expected life 4.9 – 6.6 years 5.0 – 8.1 years 6.4 – 8.0 years Risk-free interest rate 1.8 – 2.2% 1.1 – 2.3% 1.5 – 2.2%
Employee Stock Purchase Plan Valuation Assumptions	The assumptions used to estimate the per share fair value of stock purchase rights granted under the ESPP were as follows: Years Ended December 31, 2017 2016 2015 Expected volatility 28 – 42% 42 – 50% 36 – 38% Dividend yield 0.00% 0.00% 0.00% Expected life 6 – 24 months 6 – 24 months 6 – 24 months Risk-free interest rate 1.0 – 1.6% 0.4 – 0.8% 0.1 – 0.8%
Summary of Restricted Stock Unit Activity	Below is a summary of RSU activity under the plan for the year ended December 31, 2017: Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Years Aggregate Intrinsic Value Non-vested units as of December 31, 2016 2,444,966 $ 92.70 1.4 $ 202,541 Granted 1,382,900 $ 87.88 Vested (837,926 ) $ 92.00 Forfeited (310,406 ) $ 96.02 Non-vested units as of December 31, 2017 2,679,534 $ 90.04 1.4 $ 238,934
Summary of Restricted Stock Unit Awards with Performance Conditions	The following table details the base RSUs granted, RSUs earned and expected to vest and the performance multiplier achieved and compensation expense recognized for the RSUs with performance-based vesting conditions for the years ended December 31, 2017, 2016 and 2015, respectively (dollars in thousands, except per RSU amounts): Grant Date Compensation Expense for the Years Ended December 31, Date of Grant Base RSUs Granted Fair Value per RSU Multiplier Achieved RSUs Earned 2017 2016 2015 March 2017 (1) 133,250 $ 87.42 103 % 131,651 $ 4,141 $ — $ — March 2016 (2) 130,310 $ 83.43 103 % 134,219 $ 3,928 $ 2,956 $ — March 2015 (2) 58,300 $ 108.36 111 % 64,713 $ 2,291 $ 2,342 $ 1,805 (1) Based on the Company’s performance against the 2017 revenue target, the Company expects its Compensation Committee to approve a multiplier of 103% and the participating executive officers to earn 131,651 RSUs, which will continue to vest ratably over a three-year service period. (2) The RSUs with performance-based vesting conditions granted in 2016 and 2015 were earned on the one year anniversary upon achievement of the respective performance target and vest ratably over a three-year service period.
Stock-Based Compensation Expense	Compensation expense included in the Company’s Consolidated Statements of Operations for all stock-based compensation arrangements was as follows: Years Ended December 31, 2017 2016 2015 Cost of sales $ 10,636 $ 9,121 $ 6,836 Research and development 53,112 58,279 49,399 Selling, general and administrative 76,515 67,241 55,290 Total stock-based compensation expense $ 140,263 $ 134,641 $ 111,525

COMPREHENSIVE INCOME (Tables)

COMPREHENSIVE INCOME (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Amounts Reclassified out of Accumulated Other Comprehensive Income	The following table summarizes amounts reclassified out of Accumulated Other Comprehensive Income (AOCI) and their effect on the Company’s Consolidated Statements of Operations for the years ended December 31, 2017 and 2016. Amount Reclassified from AOCI (Gain) Loss Years Ended December 31, Consolidated Statement of Details about AOCI Components 2017 2016 Operations Classification Gains (losses) on cash flow hedges: Forward foreign currency exchange contracts $ (5,377 ) $ 6,112 Net product revenues Forward foreign currency exchange contracts 264 4,161 Selling, general and administrative Total gain (loss) on cash flow hedges (5,113 ) 10,273 Gain (loss) on sale of available-for-sale debt securities 3,252 (115 ) Other income (expense) Less income tax effect of the above 1,191 42 Provision for (benefit from) income taxes $ (3,052 ) $ 10,116 Net loss
Summary of Changes in Accumulated Balances of Other Comprehensive Loss Including Current Period Reclassifications Out of AOCI and Other Amount of Current Period Other Comprehensive Income	The following table summarizes changes in the accumulated balances for each component of other comprehensive loss, including current period reclassifications out of AOCI and other amounts of current-period other comprehensive income, for the years ended December 31, 2017 and 2016. Year Ended Balance at December 31, 2017 Gains and Losses on Cash Flow Hedges Unrealized Gains on Available-for-Sale Debt Securities Foreign Currency Items Total AOCI balance at December 31, 2016 13,006 (178 ) (12 ) 12,816 Other comprehensive income (loss) before reclassifications (38,351 ) (755 ) 5 (39,101 ) Less: gain (loss) reclassified from AOCI (5,113 ) 3,252 (1,861 ) Tax effect — 1,463 — 1,463 Net current-period other comprehensive income (loss) (33,238 ) (2,544 ) 5 (35,777 ) AOCI balance at December 31, 2017 $ (20,232 ) $ (2,722 ) $ (7 ) $ (22,961 ) Year Ended Balance at December 31, 2016 Gains and Losses on Cash Flow Hedges Unrealized Gains on Available-for-Sale Debt Securities Foreign Currency Items Total AOCI balance at December 31, 2015 13,602 7,441 (10 ) 21,033 Other comprehensive income (loss) before reclassifications 9,677 (12,104 ) (2 ) (2,429 ) Less: net gain (loss) reclassified from AOCI 10,273 (115 ) 10,158 Tax effect — 4,370 — 4,370 Net current-period other comprehensive loss (596 ) (7,619 ) (2 ) (8,217 ) AOCI balance at December 31, 2016 13,006 (178 ) (12 ) 12,816

REVENUE AND CREDIT CONCENTRAT47

REVENUE AND CREDIT CONCENTRATIONS (Tables) - Net Product Revenue	12 Months Ended
	Dec. 31, 2017
Geographic Concentration Risk
Concentration Risk [Line Items]
Schedules of Consolidated Net Product Revenue Concentration	The table below summarizes consolidated net product revenue concentrations based on patient location for Brineura, Firdapse, Kuvan, Naglazyme, and Vimizim, which are sold directly by the Company, and global sales of Aldurazyme, which is marketed by Genzyme. Genzyme is the Company ’ Years Ended December 31, 2017 2016 2015 Region: United States 39 % 37 % 39 % Europe 21 % 23 % 19 % Latin America 14 % 13 % 16 % Rest of world 19 % 19 % 15 % Total net product revenues marketed by the Company 93 % 92 % 89 % Aldurazyme net product revenues marketed by Genzyme 7 % 8 % 11 % Total net product revenue 100 % 100 % 100 %
Customer Concentration Risk
Concentration Risk [Line Items]
Schedules of Consolidated Net Product Revenue Concentration	The following table illustrates the percentage of the Company’s consolidated net product revenues attributed to the Company’s largest customers. For the Years Ended December 31, 2017 2016 2015 Customer A 18 % 19 % 15 % Customer B 14 % 13 % 13 % Customer C 10 % 10 % — Customer D 7 % 8 % 11 % Customer E 7 % 6 % 10 % Total 56 % 56 % 49 %

SEGMENT AND GEOGRAPHIC INFORMA

SEGMENT AND GEOGRAPHIC INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment and Geographic Information by Product Revenue	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. Years Ended December 31, 2017 2016 2015 Net product revenues by product: Aldurazyme $ 89,959 $ 93,749 $ 97,912 Brineura 8,595 — — Firdapse 18,890 18,028 16,037 Kuvan 407,542 348,009 239,336 Naglazyme 332,208 296,537 303,090 Vimizim 413,251 354,058 228,147 Total net product revenues $ 1,270,445 $ 1,110,381 $ 884,522
Summary of Total Revenues from External Customers and Collaborative Partners by Geographic Region	The following table summarizes 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 based on the location of Genzyme’s headquarters. Although Genzyme sells Aldurazyme worldwide, the revenues earned by the Company based on Genzyme’s net sales are included in the U.S. region as the transactions are with Genzyme whose headquarters are located in the U.S. Years Ended December 31, 2017 2016 2015 Total revenues by geographic region: United States $ 588,243 $ 507,539 $ 444,075 Europe 301,487 252,633 171,216 Latin America 182,438 147,471 142,305 Rest of world 241,478 209,211 132,299 Total revenues $ 1,313,646 $ 1,116,854 $ 889,895
Summary of Non-Monetary Long-Lived Assets by Geographic Region	The following table summarizes non-monetary long-lived assets by geographic region. Non-monetary long-lived assets primarily consist of property, plant and equipment, intangible assets, deferred tax assets and goodwill. December 31, 2017 2016 Long-lived assets by geography: United States $ 1,183,791 $ 1,183,938 Europe 823,657 812,833 Rest of world 2,694 2,568 Total long-lived assets $ 2,010,142 $ 1,999,339

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Schedule of Minimum Lease Payments for Future Years	Minimum lease payments for future years are as follows: 2018 $ 9,697 2019 7,671 2020 5,996 2021 4,948 2022 3,961 Thereafter 5,851 Total $ 38,124

Nature of Operations and Busi50

Nature of Operations and Business Risks - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017Product
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of approved commercial products	6

Schedule of Property Plant and

Schedule of Property Plant and Equipment (Detail)	12 Months Ended
	Dec. 31, 2017
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, estimated useful life	Shorter of life of asset or lease term
Building and Improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	15 years
Building and Improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	50 years
Manufacturing and Laboratory Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	5 years
Manufacturing and Laboratory Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	18 years
Computer Hardware and Software | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	3 years
Computer Hardware and Software | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	10 years
Office Furniture and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	5 years
Office Furniture and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	10 years
Vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	5 years
Land Improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	5 years
Land Improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life, (in years)	10 years

Summary of Significant Accoun52

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017Segment
Significant Accounting Policies [Line Items]
Number of operating business segment	1
Aldurazyme | Minimum
Significant Accounting Policies [Line Items]
Payment received as percentage of net product sales	39.50%
Aldurazyme | Maximum
Significant Accounting Policies [Line Items]
Payment received as percentage of net product sales	50.00%

Recent Accounting Pronounceme53

Recent Accounting Pronouncements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Recent Accounting Pronouncements [Line Items]
Reduction in accumulated deficit			$ 131,273
Increase in accounts receivable		$ 25,256	$ 51,483	$ 16,367
Adopting ASC Topic 606 | Scenario Forecast
Recent Accounting Pronouncements [Line Items]
Reduction in accumulated deficit	$ 20,000
Increase in accounts receivable	26,000
Decrease in deferred tax assets	$ 6,000

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - Merck Serono $ in Thousands, € in Millions	Jan. 02, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017EUR (€)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Business combination transaction costs | $				$ 600	$ 300
Business acquisition, cash paid | $	$ 374,545	$ 374,500
Estimated useful life		through 2,024
Intangible assets amortization method		straight-line basis
A&R Kuvan Agreement
Business Acquisition [Line Items]
Maximum potential additional consideration milestone payments | €			€ 60
Pegvaliase Agreement
Business Acquisition [Line Items]
Maximum potential additional consideration milestone payments | €			€ 125

Acquisitions - Summary of Estim

Acquisitions - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail) - Merck Serono - USD ($) $ in Thousands	Jan. 02, 2016	Dec. 31, 2017	Jan. 01, 2016
Business Acquisition [Line Items]
Cash payments	$ 374,545	$ 374,500
Estimated fair value of contingent acquisition consideration payable			$ 138,974
Total consideration	$ 513,519
Kuvan intangible assets			172,961
Pegvaliase IPR&D			326,359
Inventory			14,199
Total identifiable assets acquired			$ 513,519

Amortized Cost Gross Unrealized

Amortized Cost Gross Unrealized Holding Gain or Loss and Fair Value of Available for Sale Debt Security by Major Security Type (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,230,351	$ 971,228
Gross Unrealized Holding Gains	300	452
Gross Unrealized Holding Losses	(4,592)	(3,029)
Aggregate Fair Value	1,226,059	968,651
Certificates of Deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,800
Gross Unrealized Holding Gains		0
Gross Unrealized Holding Losses		0
Aggregate Fair Value		2,800
Corporate Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	707,652	641,670
Gross Unrealized Holding Gains	150	329
Gross Unrealized Holding Losses	(2,553)	(2,282)
Aggregate Fair Value	705,249	639,717
Commercial Paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	24,566	16,075
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Aggregate Fair Value	24,566	16,075
U.S. Government Agency Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	472,593	310,635
Gross Unrealized Holding Gains	0	37
Gross Unrealized Holding Losses	(1,975)	(747)
Aggregate Fair Value	470,618	309,925
Foreign and Other
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	25,540	48
Gross Unrealized Holding Gains	150	86
Gross Unrealized Holding Losses	(64)	0
Aggregate Fair Value	$ 25,626	$ 134

Fair Values of Available-For-Sa

Fair Values of Available-For-Sale Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Maturing in one year or less	$ 840,274	$ 395,940
Maturing after one year through five years	385,785	572,711
Total	$ 1,226,059	$ 968,651

Investments - Additional Inform

Investments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)
Investments Debt And Equity Securities [Abstract]
Other- than- temporary impairment	$ 0

Intangible Assets (Detail)

Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Intangible assets:
Finite-lived intangible assets	$ 303,298	$ 305,122
Indefinite-lived intangible assets	326,359	332,199
Gross intangible assets:	629,657	637,321
Less: Accumulated amortization	(112,147)	(83,541)
Net carrying value	$ 517,510	$ 553,780

Schedule of Net-Book-Value and

Schedule of Net-Book-Value and Estimated Remaining Life of Finite-Lived Intangible Assets (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Finite-Lived Intangible Assets [Line Items]
Net Balance at December 31, 2017	$ 191,151
Repurchased royalty rights
Finite-Lived Intangible Assets [Line Items]
Net Balance at December 31, 2017	$ 39,938
Remaining Life (in years)	5 years 10 months 24 days
Acquired intellectual property
Finite-Lived Intangible Assets [Line Items]
Net Balance at December 31, 2017	$ 149,229
Remaining Life (in years)	7 years 2 months 12 days
License payments for marketing approvals
Finite-Lived Intangible Assets [Line Items]
Net Balance at December 31, 2017	$ 1,357
Remaining Life (in years)	4 years 4 months 24 days
In-place and above market tenant leases
Finite-Lived Intangible Assets [Line Items]
Net Balance at December 31, 2017	$ 627
In-place and above market tenant leases | Minimum
Finite-Lived Intangible Assets [Line Items]
Remaining Life (in years)	8 months 12 days
In-place and above market tenant leases | Maximum
Finite-Lived Intangible Assets [Line Items]
Remaining Life (in years)	5 years 7 months 6 days

Schedule of Future Amortization

Schedule of Future Amortization Expense of Finite-Lived Intangible Assets (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
2,018	$ 30,400
2,019	30,086
2,020	27,605
2,021	26,681
2,022	26,657
Thereafter	49,722
Finite-lived intangible assets, net	$ 191,151

Schedule of Indefinite Lived In

Schedule of Indefinite Lived Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Indefinite-lived Intangible Assets [Line Items]
Net carrying value	$ 326,359	$ 332,199
Pegvaliase
Indefinite-lived Intangible Assets [Line Items]
In-process research and development acquired	326,359	326,359
Other Acquired Pre-Clinical Compounds
Indefinite-lived Intangible Assets [Line Items]
In-process research and development acquired	$ 0	$ 5,840

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets [Line Items]
Impairment charge			$ 0	$ 599,118,000	$ 198,700,000
Indefinite-lived intangible assets	$ 326,359,000	$ 326,359,000	326,359,000	332,199,000
Proceeds from sale of intangible asset			125,000,000	0	410,000,000
IPR&D of Kyndrisa and Other Exon
Goodwill And Intangible Assets [Line Items]
Impairment charge				574,100,000	$ 198,700,000
Indefinite-lived intangible assets	0	0	$ 0
IPR&D of Reveglucosidase Alfa
Goodwill And Intangible Assets [Line Items]
Impairment charge				$ 25,000,000
Rare Pediatric Disease Priority Review Voucher
Goodwill And Intangible Assets [Line Items]
Proceeds from sale of intangible asset	$ 125,000,000
IPR&D
Goodwill And Intangible Assets [Line Items]
Impairment charge		$ 5,800,000

Property Plant and Equipment (D

Property Plant and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,303,434	$ 1,141,362
Less: Accumulated depreciation	(406,734)	(342,594)
Total property, plant and equipment, net	896,700	798,768
Building and Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	663,347	510,805
Manufacturing and Laboratory Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	294,521	242,899
Computer Hardware and Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	144,268	129,506
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	42,572	44,184
Furniture and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	31,515	27,229
Land Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,331	4,881
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	62,369	55,412
Construction-in-Progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 59,511	$ 126,446

Property Plant and Equipment -

Property Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Abstract]
Depreciation expense	$ 75,800	$ 73,200	$ 50,100
Depreciation capitalized into inventory	$ 24,076	$ 17,375	$ 14,627

Schedule of Inventory (Detail)

Schedule of Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 49,877	$ 51,250
Work-in-process	234,674	167,788
Finished goods	191,224	136,088
Total inventory	$ 475,775	$ 355,126

Schedule of Accounts Payable an

Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Accounts payable and accrued operating expenses	$ 166,616	$ 191,353
Accrued compensation expense	140,781	109,038
Accrued rebates payable	36,472	34,737
Accrued royalties payable	18,820	15,151
Value added taxes payable	9,740	7,848
Forward foreign currency exchange contracts	14,464	5,201
Accrued income taxes	5,528	0
Other	9,500	7,177
Total accounts payable and accrued liabilities	$ 401,921	$ 370,505

Schedule of Estimated Accrued R

Schedule of Estimated Accrued Rebates and Reserve for Cash Discounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accrued Rebates
Supplemental Balance Sheet Information [Line Items]
Balance at Beginning of Period	$ 34,737	$ 32,553	$ 14,859
Provision for Current Period Sales	56,282	44,347	45,356
Provision/(Reversals) for Prior Period Sales	(3,686)	(5,205)	(1,245)
Actual Charges Related to Current Period Sales	(31,714)	(23,879)	(18,421)
Actual Charges Related to Prior Period Sales	(19,147)	(13,079)	(7,996)
Balance at End of Period	36,472	34,737	32,553
Reserve for Cash Discount
Supplemental Balance Sheet Information [Line Items]
Balance at Beginning of Period	888	831	688
Provision for Current Period Sales	10,730	8,889	7,402
Provision/(Reversals) for Prior Period Sales	(58)	(22)	0
Actual Charges Related to Current Period Sales	(9,601)	(8,160)	(6,722)
Actual Charges Related to Prior Period Sales	(904)	(650)	(537)
Balance at End of Period	$ 1,055	$ 888	$ 831

Summary of Designated Forward F

Summary of Designated Forward Foreign Currency Exchange Contracts Outstanding (Detail) - Foreign exchange contracts	12 Months Ended
	Dec. 31, 2017EUR (€)Derivative	Dec. 31, 2017BRLDerivative	Dec. 31, 2017CADDerivative	Dec. 31, 2017COPDerivative
Maximum
Derivative [Line Items]
Maturity	Dec. 31, 2020
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Number of Contracts	411	411	411	411
Derivatives Designated As Hedging Instruments | Euros | Purchase
Derivative [Line Items]
Number of Contracts	80	80	80	80
Aggregate Notional Amount in Foreign Currency | €	€ 122,200,000
Derivatives Designated As Hedging Instruments | Euros | Purchase | Minimum
Derivative [Line Items]
Maturity	Jan. 1, 2018
Derivatives Designated As Hedging Instruments | Euros | Purchase | Maximum
Derivative [Line Items]
Maturity	Dec. 31, 2020
Derivatives Designated As Hedging Instruments | Euros | Sell
Derivative [Line Items]
Number of Contracts	289	289	289	289
Aggregate Notional Amount in Foreign Currency | €	€ 373,500,000
Derivatives Designated As Hedging Instruments | Euros | Sell | Minimum
Derivative [Line Items]
Maturity	Jan. 1, 2018
Derivatives Designated As Hedging Instruments | Euros | Sell | Maximum
Derivative [Line Items]
Maturity	Dec. 31, 2020
Derivatives Designated As Hedging Instruments | Canadian Dollars | Sell
Derivative [Line Items]
Number of Contracts	24	24	24	24
Aggregate Notional Amount in Foreign Currency | CAD			CAD 27,200,000
Derivatives Designated As Hedging Instruments | Canadian Dollars | Sell | Minimum
Derivative [Line Items]
Maturity	Jan. 1, 2018
Derivatives Designated As Hedging Instruments | Canadian Dollars | Sell | Maximum
Derivative [Line Items]
Maturity	Dec. 31, 2018
Derivatives Designated As Hedging Instruments | Colombian Pesos | Sell
Derivative [Line Items]
Number of Contracts	12	12	12	12
Aggregate Notional Amount in Foreign Currency | COP				COP 93,000,000,000
Derivatives Designated As Hedging Instruments | Colombian Pesos | Sell | Minimum
Derivative [Line Items]
Maturity	Jan. 1, 2018
Derivatives Designated As Hedging Instruments | Colombian Pesos | Sell | Maximum
Derivative [Line Items]
Maturity	Dec. 31, 2018
Derivatives Designated As Hedging Instruments | Brazilian Reais | Sell
Derivative [Line Items]
Number of Contracts	6	6	6	6
Aggregate Notional Amount in Foreign Currency | BRL		BRL 160,000,000
Maturity	May 31, 2018

Derivative Instruments and He70

Derivative Instruments and Hedging Strategies - Additional Information (Detail) - Foreign Currency Derivatives $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Derivative [Line Items]
Amount reclassified from accumulated other comprehensive income (loss) to earnings as related to forecasted revenue and operating expense transactions	$ 12.1
Maximum length of time over which hedging its exposure to the reduction in value of forecasted foreign currency cash flows through foreign currency forward contracts	12 months
Maximum
Derivative [Line Items]
Maturity period of foreign currency derivatives	Dec. 31, 2020

Summary of Non-Designated Forwa

Summary of Non-Designated Forward Foreign Currency Exchange Contracts Outstanding (Detail) - Not Designated as Hedging Instrument - Foreign exchange contracts	12 Months Ended
	Dec. 31, 2017EUR (€)Derivative	Dec. 31, 2017GBP (£)Derivative
Derivative [Line Items]
Number of Contracts	5	5
Euros | Purchase
Derivative [Line Items]
Number of Contracts	4	4
Aggregate Notional Amount in Foreign Currency | €	€ 93,500,000
Maturity	Jan. 1, 2018
United Kingdom, Pounds | Sell
Derivative [Line Items]
Number of Contracts	1	1
Aggregate Notional Amount in Foreign Currency | £		£ 5,000,000
Maturity	Jan. 1, 2018

Fair Value Carrying Amount of D

Fair Value Carrying Amount of Derivative Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative Asset, Fair Value	$ 9,663	$ 22,206
Derivative Liability, Fair Value	27,150	7,543
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Derivative Asset, Fair Value	8,988	21,242
Derivative Liability, Fair Value	27,106	7,518
Derivatives Designated As Hedging Instruments | Forward Foreign Currency Exchange Contracts | Other Current Assets
Derivative [Line Items]
Derivative Asset, Fair Value	4,015	13,048
Derivatives Designated As Hedging Instruments | Forward Foreign Currency Exchange Contracts | Other Assets
Derivative [Line Items]
Derivative Asset, Fair Value	4,973	8,194
Derivatives Designated As Hedging Instruments | Forward Foreign Currency Exchange Contracts | Accounts Payable and Accrued Liabilities
Derivative [Line Items]
Derivative Liability, Fair Value	14,420	5,176
Derivatives Designated As Hedging Instruments | Forward Foreign Currency Exchange Contracts | Other Long-Term Liabilities
Derivative [Line Items]
Derivative Liability, Fair Value	12,686	2,342
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value	675	964
Derivative Liability, Fair Value	44	25
Not Designated as Hedging Instrument | Forward Foreign Currency Exchange Contracts | Other Current Assets
Derivative [Line Items]
Derivative Asset, Fair Value	675	964
Not Designated as Hedging Instrument | Forward Foreign Currency Exchange Contracts | Accounts Payable and Accrued Liabilities
Derivative [Line Items]
Derivative Liability, Fair Value	$ 44	$ 25

Effect of Derivative Instrument

Effect of Derivative Instruments (Detail) - Forward Foreign Currency Exchange Contracts - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivatives Designated As Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) recognized in accumulated other comprehensive loss	[1]	$ (38,351)	$ 9,677	$ 17,300
Net gain (loss) reclassified from accumulated other comprehensive income (loss) into earnings	[2]	(5,113)	6,529	19,604
Net gain (loss) recognized in net loss	[3]	2,576	5,070	(727)
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) recognized in net loss	[4]	$ 8,255	$ (8,687)	$ 4,493
[1]	(1) Net change in the fair value of the effective portion classified as accumulated other comprehensive income (loss).
[2]	(2) Effective portion classified as Net Product Revenues and SG&A expense.
[3]	(3) Ineffective portion and amount excluded from effectiveness testing classified as SG&A expense.
[4]	(4) Classified as SG&A expense.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities (Detail) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of total available-for-sale debt securities		$ 1,226,059	$ 968,651
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		257,775	250,164
Fair value of total available-for-sale debt securities		1,183,725	954,058
Fair value of other current assets		21,304	17,929
Fair value of other non-current assets		16,832	21,379
Fair value of financial assets, Total		1,479,636	1,243,530
Fair value of other current liabilities		70,435	53,764
Fair value of other non-current liabilities		178,135	144,076
Fair value of financial liabilities, Total		248,570	197,840
Fair Value, Measurements, Recurring | Money Market Instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		215,441	235,571
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		2,323	2,236
Fair value of other non-current liabilities		30,131	26,424
Fair Value, Measurements, Recurring | Forward Foreign Currency Exchange Contract, Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	[1]	14,464	5,201
Fair value of other non-current liabilities	[1]	12,686	2,342
Fair Value, Measurements, Recurring | Contingent Acquisition Consideration Payable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities		53,648	46,327
Fair value of other non-current liabilities		135,318	115,310
Fair Value, Measurements, Recurring | Quoted Price In Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0	0
Fair value of total available-for-sale debt securities		0	0
Fair value of other current assets		0	0
Fair value of other non-current assets		0	4,064
Fair value of financial assets, Total		0	4,064
Fair value of other current liabilities		1,356	2,073
Fair value of other non-current liabilities		18,272	17,303
Fair value of financial liabilities, Total		19,628	19,376
Fair Value, Measurements, Recurring | Quoted Price In Active Markets For Identical Assets (Level 1) | Money Market Instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0	0
Fair Value, Measurements, Recurring | Quoted Price In Active Markets For Identical Assets (Level 1) | NQDC Plan Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities		1,356	2,073
Fair value of other non-current liabilities		18,272	17,303
Fair Value, Measurements, Recurring | Quoted Price In Active Markets For Identical Assets (Level 1) | Forward Foreign Currency Exchange Contract, Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	[1]	0	0
Fair value of other non-current liabilities	[1]	0	0
Fair Value, Measurements, Recurring | Quoted Price In Active Markets For Identical Assets (Level 1) | Contingent Acquisition Consideration Payable
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 Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		257,775	250,164
Fair value of total available-for-sale debt securities		1,183,725	954,058
Fair value of other current assets		21,304	17,929
Fair value of other non-current assets		16,832	17,315
Fair value of financial assets, Total		1,479,636	1,239,466
Fair value of other current liabilities		15,431	5,364
Fair value of other non-current liabilities		24,545	11,463
Fair value of financial liabilities, Total		39,976	16,827
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Money Market Instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		215,441	235,571
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		967	163
Fair value of other non-current liabilities		11,859	9,121
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Forward Foreign Currency Exchange Contract, Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	[1]	14,464	5,201
Fair value of other non-current liabilities	[1]	12,686	2,342
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Contingent Acquisition Consideration Payable
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)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0	0
Fair value of total available-for-sale debt securities		0	0
Fair value of other current assets		0	0
Fair value of other non-current assets		0	0
Fair value of financial assets, Total		0	0
Fair value of other current liabilities		53,648	46,327
Fair value of other non-current liabilities		135,318	115,310
Fair value of financial liabilities, Total		188,966	161,637
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Money Market Instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0	0
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) | Forward Foreign Currency Exchange Contract, Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities	[1]	0	0
Fair value of other non-current liabilities	[1]	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Contingent Acquisition Consideration Payable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities		53,648	46,327
Fair value of other non-current liabilities		135,318	115,310
Fair Value, Measurements, Recurring | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		3,096	8,593
Fair value of Available-for-sale debt securities, current		406,188	193,974
Fair value of Available-for-sale debt securities, non-current		295,965	437,150
Fair Value, Measurements, Recurring | Corporate Debt Securities | Quoted Price In Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0	0
Fair value of Available-for-sale debt securities, current		0	0
Fair value of Available-for-sale debt securities, non-current		0	0
Fair Value, Measurements, Recurring | Corporate Debt Securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		3,096	8,593
Fair value of Available-for-sale debt securities, current		406,188	193,974
Fair value of Available-for-sale debt securities, non-current		295,965	437,150
Fair Value, Measurements, Recurring | Corporate Debt Securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0	0
Fair value of Available-for-sale debt securities, current		0	0
Fair value of Available-for-sale debt securities, non-current		0	0
Fair Value, Measurements, Recurring | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		2,751
Fair value of Available-for-sale debt securities, current		21,815	16,075
Fair Value, Measurements, Recurring | Commercial Paper | Quoted Price In Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0
Fair value of Available-for-sale debt securities, current		0	0
Fair Value, Measurements, Recurring | Commercial Paper | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		2,751
Fair value of Available-for-sale debt securities, current		21,815	16,075
Fair Value, Measurements, Recurring | Commercial Paper | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0
Fair value of Available-for-sale debt securities, current		0	0
Fair Value, Measurements, Recurring | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		35,497	6,000
Fair value of Available-for-sale debt securities, current		345,501	168,498
Fair value of Available-for-sale debt securities, non-current		89,620	135,427
Fair Value, Measurements, Recurring | U.S. Government Agency Securities | Quoted Price In Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0	0
Fair value of Available-for-sale debt securities, current		0	0
Fair value of Available-for-sale debt securities, non-current		0	0
Fair Value, Measurements, Recurring | U.S. Government Agency Securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		35,497	6,000
Fair value of Available-for-sale debt securities, current		345,501	168,498
Fair value of Available-for-sale debt securities, non-current		89,620	135,427
Fair Value, Measurements, Recurring | U.S. Government Agency Securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0	0
Fair value of Available-for-sale debt securities, current		0	0
Fair value of Available-for-sale debt securities, non-current		0	0
Fair Value, Measurements, Recurring | Foreign and Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		990
Fair value of Available-for-sale debt securities, current		24,436
Fair value of Available-for-sale debt securities, non-current		200	134
Fair Value, Measurements, Recurring | Foreign and Other | Quoted Price In Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0
Fair value of Available-for-sale debt securities, current		0
Fair value of Available-for-sale debt securities, non-current		0	0
Fair Value, Measurements, Recurring | Foreign and Other | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		990
Fair value of Available-for-sale debt securities, current		24,436
Fair value of Available-for-sale debt securities, non-current		200	134
Fair Value, Measurements, Recurring | Foreign and Other | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of cash and cash equivalents including available-for-sale debt securities		0
Fair value of Available-for-sale debt securities, current		0
Fair value of Available-for-sale debt securities, non-current		0	0
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		967	163
Fair value of other non-current assets		11,859	9,121
Fair Value, Measurements, Recurring | NQDC Plan Assets | Quoted Price In Active Markets For Identical Assets (Level 1)
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 | 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		967	163
Fair value of other non-current assets		11,859	9,121
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 | Forward Foreign Current Exchange Contract Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	[1]	4,690	14,012
Fair value of other non-current assets	[1]	4,973	8,194
Fair Value, Measurements, Recurring | Forward Foreign Current Exchange Contract Assets | Quoted Price In Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	[1]	0	0
Fair value of other non-current assets	[1]	0	0
Fair Value, Measurements, Recurring | Forward Foreign Current Exchange Contract 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	[1]	4,690	14,012
Fair value of other non-current assets	[1]	4,973	8,194
Fair Value, Measurements, Recurring | Forward Foreign Current Exchange Contract 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	[1]	0	0
Fair value of other non-current assets	[1]	0	0
Fair Value, Measurements, Recurring | Restrictive Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	[2]	15,647	3,754
Fair Value, Measurements, Recurring | Restrictive Investments | Quoted Price In Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	[2]	0	0
Fair Value, Measurements, Recurring | Restrictive Investments | 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]	15,647	3,754
Fair Value, Measurements, Recurring | Restrictive Investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	[2]	$ 0	0
Fair Value, Measurements, Recurring | Certificates of Deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of Available-for-sale debt securities, current			2,800
Fair Value, Measurements, Recurring | Certificates of Deposit | Quoted Price In Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of Available-for-sale debt securities, current			0
Fair Value, Measurements, Recurring | Certificates of Deposit | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of Available-for-sale debt securities, current			2,800
Fair Value, Measurements, Recurring | Certificates of Deposit | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of Available-for-sale debt securities, current			0
Fair Value, Measurements, Recurring | Strategic Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	[3]		4,064
Fair Value, Measurements, Recurring | Strategic Investment | Quoted Price In Active Markets For Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	[3]		4,064
Fair Value, Measurements, Recurring | Strategic Investment | 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	[3]		0
Fair Value, Measurements, Recurring | Strategic Investment | 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	[3]		$ 0
[1]	See Note 11 to these Consolidated Financial Statements for further information regarding the derivative instruments.
[2]	The restricted investments as of December 31, 2017 and 2016 secure the Company’s irrevocable standby letter of credit obtained in connection with certain commercial agreements.
[3]	The Company had investments in marketable equity securities measured using quoted prices in an active market that are considered strategic investments and included in Other Assets on the Company’s Balance Sheets. As of December 31, 2017, all holdings in the Company’s strategic investments have been liquidated.

Liabilities Measured at Fair Va

Liabilities Measured at Fair Value Using Level 3 Inputs (Detail) - Contingent Payment $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent acquisition consideration payable, Beginning balance	$ 161,637
Changes in the fair value of other contingent acquisition consideration payable	14,587
Foreign exchange remeasurement of Euro denominated contingent acquisition consideration payable	20,487
Contingent acquisition consideration payable, Ending balance	188,966
Huxley Pharmaceuticals, Inc.
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Milestone payments to former shareholders	(3,500)
Firdapse
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Reversal of contingent liability related to revised estimate of Firdapse FDA acceptance and approval milestones	$ (4,245)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) $ in Millions	Dec. 31, 2017USD ($)
Fair Value Disclosures [Abstract]
Asset retirement obligations	$ 4.2

Debt - Additional Information (

Debt - Additional Information (Detail)	Apr. 23, 2017USD ($)	Oct. 15, 2013USD ($)	Aug. 31, 2017USD ($)$ / shares	Nov. 30, 2016USD ($)	Oct. 31, 2013USD ($)	Apr. 30, 2007USD ($)$ / sharesshares	Dec. 31, 2017USD ($)d$ / shares$ / Optionshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Feb. 13, 2015USD ($)$ / shares
Revolving Credit Facility
Debt Instrument [Line Items]
Maturity date of convertible debt				Nov. 29, 2018
Maximum borrowing capacity				$ 100,000,000
Frequency of interest payment							0
Amortization expense				600,000
Outstanding amount							$ 0
Debt instrument liquidity covenant assets, maximum							225,000,000
Letter of credit subfacility
Debt Instrument [Line Items]
Maximum borrowing capacity				10,000,000
Swing line loan subfacility
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 15,000,000
Convertible Senior Notes
Debt Instrument [Line Items]
Amortization expense							$ 3,725,000	$ 3,367,000	$ 3,294,000
Convertible Notes due in 2024
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount			$ 495,000,000
Maturity date of convertible debt			Aug. 1, 2024
Frequency of periodic payment							semi-annually in cash on February 1 and August 1 of each year
Interest payable beginning date			Feb. 1, 2018
Debt instrument percentage of face value			98.00%
Debt instrument, interest rate, stated percentage, per annum			0.599%
Debt instrument, effective interest rate							1.10%
Conversion rate of shares			8.0212
Principal amount on conversion rate			$ 1,000,000
Debt instrument, convertible, conversion price, per share | $ / shares			$ 124.67
Net proceeds from offering debt			$ 481,700,000
Repurchase of note principal amount							100.00%
Debt issuance costs							$ 3,400,000
Debt Instrument, unamortized discount			$ 9,900,000				9,355,000	0
Carrying value of equity component							495,000,000	0
Offering costs							$ 3,199,000	$ 0
Convertible Notes due 2018 and due 2020
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount		$ 750,000,000
Conversion rate of shares							10.6213
Principal amount on conversion rate										$ 1,000
Debt instrument, convertible, conversion price, per share | $ / shares							$ 94.15	$ 94.15	$ 94.15	$ 94.15
Net proceeds from offering debt		726,200,000
Repurchase of note principal amount							100.00%
Debt issuance costs							$ 23,800,000
Common stock trading day | d							20
Consecutive common stock trading days | d							30
Debt instrument convertible threshold percentage							130.00%
Number of business day period							5 days
Trading price percentage on reported sale price of common stock							98.00%
Carrying value of equity component							$ 156,200,000
Common stock shares covered under capped call transactions | shares							3,982,988
Strike price | $ / Option							94.15
Cap price | $ / Option							121.05
Payment for capped calls transactions					$ 29,800,000
Convertible Notes due 2018 and due 2020 | Convertible Senior Notes
Debt Instrument [Line Items]
Debt Instrument, unamortized discount							$ 161,300,000
Offering costs							$ 5,100,000
Convertible Notes due 2018
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount		$ 375,000,000
Maturity date of convertible debt		Oct. 15, 2018
Debt instrument, interest rate, stated percentage, per annum		0.75%
Debt instrument, effective interest rate							6.00%
Debt Instrument, unamortized discount							$ 12,488,000	$ 27,566,000
Carrying value of equity component							374,980,000	374,980,000
Offering costs							$ 1,543,000	3,484,000
Convertible Notes due 2020
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount		$ 375,000,000
Maturity date of convertible debt		Oct. 15, 2020
Debt instrument, interest rate, stated percentage, per annum		1.50%
Debt instrument, effective interest rate							7.50%
Conversion rate of shares							10.6213
Principal amount on conversion rate										$ 1,000
Debt instrument, convertible, conversion price, per share | $ / shares										$ 94.15
Debt Instrument, unamortized discount							$ 40,287,000	53,239,000
Carrying value of equity component							374,993,000	374,993,000
Offering costs							3,631,000	4,923,000
Convertible Notes due 2017
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount						$ 324,900,000
Maturity date of convertible debt						Apr. 23, 2017
Debt instrument, interest rate, stated percentage, per annum						1.875%
Conversion rate of shares						49.1171
Principal amount on conversion rate						$ 1,000
Debt instrument, convertible, conversion price, per share | $ / shares						$ 20.36
Carrying value of equity component							0	22,503,000
Offering costs							0	25,000
Convertible notes aggregate principal							$ 22,500,000	$ 8,900,000	$ 8,100,000
Notes converted, number of shares | shares						1,103,998		438,462	399,469
Debt conversion, final cash settlement amount	$ 26,000

Summary of Convertible Debt (De

Summary of Convertible Debt (Detail) - USD ($) $ in Thousands		Dec. 31, 2017	Aug. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Convertible Notes, net of unamortized deferred offering costs		$ 360,949		$ 22,478
Convertible Notes, net of unamortized discount and deferred offering costs		813,521		660,761
Total convertible debt, net		1,174,470		683,239
Convertible Notes, fair value		1,344,319		956,933
Convertible Notes due 2017
Debt Instrument [Line Items]
Convertible Notes		0		22,503
Convertible debt, Unamortized deferred offering costs		0		(25)
Convertible Notes, net of unamortized deferred offering costs		0		22,478
Convertible Notes, fair value	[1]	0		90,977
Convertible Notes due 2018
Debt Instrument [Line Items]
Convertible Notes		374,980		374,980
Convertible debt, unamortized discount		(12,488)		(27,566)
Convertible debt, Unamortized deferred offering costs		(1,543)		(3,484)
Convertible Notes, net of unamortized discount and deferred offering costs		360,949		343,930
Convertible Notes, fair value	[1]	403,955		423,202
Convertible Notes due 2020
Debt Instrument [Line Items]
Convertible Notes		374,993		374,993
Convertible debt, unamortized discount		(40,287)		(53,239)
Convertible debt, Unamortized deferred offering costs		(3,631)		(4,923)
Convertible Notes, net of unamortized discount and deferred offering costs		331,075		316,831
Convertible Notes, fair value	[1]	446,470		442,754
Convertible Notes due in 2024
Debt Instrument [Line Items]
Convertible Notes		495,000		0
Convertible debt, unamortized discount		(9,355)	$ (9,900)	0
Convertible debt, Unamortized deferred offering costs		(3,199)		0
Convertible Notes, net of unamortized discount and deferred offering costs		482,446		0
Convertible Notes, fair value	[1]	$ 493,894		$ 0
[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.

Summary of Interest Expense on

Summary of Interest Expense on Debt (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Interest Expenses [Line Items]
Total interest expense on convertible debt	$ 42,707	$ 39,499	$ 38,244
Convertible Senior Notes
Schedule Of Interest Expenses [Line Items]
Coupon interest	10,407	9,555	9,750
Amortization of debt issuance costs	3,725	3,367	3,294
Accretion of discount on convertible notes	28,575	26,577	25,200
Total interest expense on convertible debt	$ 42,707	$ 39,499	$ 38,244

Computation of Basic and Dilute

Computation of Basic and Diluted Earnings per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net loss, basic	$ (117,042)	$ (630,210)	$ (171,799)
Less: gain on common stock held by the NQDC	0	(3,184)	0
Net loss, diluted	$ (117,042)	$ (633,394)	$ (171,799)
Weighted-average common shares outstanding, basic	174,427	165,985	160,025
Common stock held by the NQDC	0	234	0
Weighted-average common shares outstanding, diluted	174,427	166,219	160,025
Net loss per common share, basic	$ (0.67)	$ (3.80)	$ (1.07)
Net loss per common share, diluted	$ (0.67)	$ (3.81)	$ (1.07)

Anti-Dilutive Common Stock Excl

Anti-Dilutive Common Stock Excluded From Computation of Basic and Diluted Net Loss Per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of earnings (loss) per share as they are anti-dilutive	23,611	20,949	22,131
Stock Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of earnings (loss) per share as they are anti-dilutive	8,108	8,856	10,323
Common stock issuable under the 2017 Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of earnings (loss) per share as they are anti-dilutive	0	1,105	1,544
Common stock issuable under the 2018 Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of earnings (loss) per share as they are anti-dilutive	3,983	3,983	3,983
Common stock issuable under the 2020 Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of earnings (loss) per share as they are anti-dilutive	3,983	3,983	3,983
Unvested restricted stock units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of earnings (loss) per share as they are anti-dilutive	2,911	2,618	1,743
Common stock issuable under the 2024 Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of earnings (loss) per share as they are anti-dilutive	3,970	0	0
Common stock potentially issuable for ESPP purchases
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of earnings (loss) per share as they are anti-dilutive	436	404	312
Common stock held by the NQDC
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential shares of common stock excluded from computation of earnings (loss) per share as they are anti-dilutive	220	0	243

Net Loss Per Common Share - Add

Net Loss Per Common Share - Additional Information (Detail) - $ / shares	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Feb. 13, 2015
Convertible Notes due 2018 and due 2020
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price, per share	$ 94.15	$ 94.15	$ 94.15	$ 94.15

Provision for Benefit from Inco

Provision for Benefit from Income Taxes Based Loss Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. Source	$ (19,461)	$ 10,696	$ 182,215
Non-U.S. Source	(16,414)	(841,746)	(336,939)
Loss before income taxes	$ (35,875)	$ (831,050)	$ (154,724)

Components of Provision for (Be

Components of Provision for (Benefit from) Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components Of Income Tax Expense Benefit Continuing Operations [Abstract]
Federal	$ 29,848	$ 22,239	$ 84,743
State and local	2,880	1,418	5,323
Foreign	3,975	3,557	3,836
Current income tax expense, total	36,703	27,214	93,902
Federal	12,446	(78,428)	(17,741)
State and local	32,336	(6,012)	(8,770)
Foreign	(318)	(143,614)	(50,316)
Deferred income tax expense (benefit), total	44,464	(228,054)	(76,827)
Provision for (benefit from) income taxes	$ 81,167	$ (200,840)	$ 17,075

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Corporate income tax rate			35.00%	35.00%	35.00%
Provisional expense related to 2017 Tax Act			$ 42,300
Amount for re-measurement of net deferred tax assets			33,100
Increased limitations on executive compensation			9,200
Income tax expense			$ 81,167	$ (200,840)	$ 17,075
Deemed repatriation toll tax on accumulated earnings of foreign subsidiaries, impact			The 2017 Tax Act also includes a one-time mandatory deemed repatriation toll tax on accumulated earnings of our foreign subsidiaries that did not impact the Company due to a net deficit in these foreign subsidiaries.
Impairment	$ 2,609		$ 2,609	5,017
Deferred income taxes			44,464	(228,054)	$ (76,827)
Net operating loss carryforwards	48,374		48,374	49,787
Unrecognized tax benefits that would affect the effective tax rate if recognized	113,500		113,500
Undistributed earnings of foreign subsidiaries	10,700		$ 10,700
Minimum
Income Tax Contingency [Line Items]
Income Tax Statute Of Limitations Period			3 years
Maximum
Income Tax Contingency [Line Items]
Income Tax Statute Of Limitations Period			5 years
Dutch | Kyndrisa | IPR&D
Income Tax Contingency [Line Items]
Impairment				539,200
Deferred income taxes				$ (143,500)
Valuation Allowance against State Tax Credits
Income Tax Contingency [Line Items]
Income tax expense	41,400
Domestic
Income Tax Contingency [Line Items]
Reduction in orphan drug credit benefit due to change in tax rate			50.00%
Net operating loss carryforwards	15,554		$ 15,554
Research credit carry forward	403,828		403,828
Foreign | Dutch
Income Tax Contingency [Line Items]
Net operating loss carryforwards	145,150		145,150
Foreign | Irish
Income Tax Contingency [Line Items]
Net operating loss carryforwards	9,500		9,500
State
Income Tax Contingency [Line Items]
Net operating loss carryforwards	108,133		108,133
Research credit carry forward	$ 83,700		$ 83,700
Scenario Forecast
Income Tax Contingency [Line Items]
Corporate income tax rate		21.00%

Reconciliation of Statutory Fed

Reconciliation of Statutory Federal Income Tax Rate to Company Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Federal statutory income tax rate	35.00%	35.00%	35.00%
State and local taxes	(20.30%)	0.40%	(2.20%)
Orphan Drug & General Business Credit	93.90%	7.50%	34.80%
Stock compensation expense	19.10%	4.60%	(2.80%)
Changes in the fair value of contingent acquisition consideration payable	(3.10%)	0.90%	0.20%
Subpart F income	(84.10%)		(8.40%)
Foreign tax rate differential	(26.20%)	(18.60%)	(46.20%)
Section 162(m) limitation	(26.50%)	(5.40%)	(1.30%)
Tax Cuts and Jobs Act of 2017	(118.00%)
Other	1.90%	0.30%	(1.60%)
Valuation allowance/deferred benefit	(97.90%)	(0.50%)	(18.50%)
Effective income tax rate	(226.20%)	24.20%	(11.00%)

Components of Company Net Defer

Components of Company Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 48,374	$ 49,787
Tax credit carryforwards	384,381	352,535
Accrued expenses, reserves, and prepaids	54,565	77,904
Intangible assets	17,556	26,751
Stock-based compensation	31,371	47,713
Inventory	13,206	15,581
Impairment	2,609	5,017
Other	2,358	1,519
Valuation allowance	(111,001)	(73,037)
Total deferred tax assets	443,419	503,770
Joint venture basis difference	(1,229)	(1,714)
Acquired intangibles	(3,332)	(8,773)
Convertible notes discount	(10,100)	(24,394)
Property, plant and equipment	(29,663)	(22,103)
Total deferred tax liabilities	(44,324)	(56,984)
Net deferred tax assets	$ 399,095	$ 446,786

Summary of Expiration of not Ut

Summary of Expiration of not Utilized Net Operating Loss and Tax Credit Carryforwards (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 48,374	$ 49,787
Federal
Income Tax Contingency [Line Items]
Net operating loss carryforwards	15,554
Federal R&D and orphan drug credit carryforwards	$ 403,828
Federal | Minimum
Income Tax Contingency [Line Items]
Operating loss carry forward if not utilized, expiration date	2,028
Federal R&D and orphan drug credit carryforwards, expiration date	2,030
Federal | Maximum
Income Tax Contingency [Line Items]
Operating loss carry forward if not utilized, expiration date	2,033
Federal R&D and orphan drug credit carryforwards, expiration date	2,037
State
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 108,133
Federal R&D and orphan drug credit carryforwards	$ 83,700
State | Minimum
Income Tax Contingency [Line Items]
Operating loss carry forward if not utilized, expiration date	2,019
State | Maximum
Income Tax Contingency [Line Items]
Operating loss carry forward if not utilized, expiration date	2,036
Dutch | Foreign
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 145,150
Dutch | Foreign | Minimum
Income Tax Contingency [Line Items]
Operating loss carry forward if not utilized, expiration date	2,020
Dutch | Foreign | Maximum
Income Tax Contingency [Line Items]
Operating loss carry forward if not utilized, expiration date	2,025

Reconciliation of Unrecognized

Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Balance at beginning of period	$ 103,210	$ 86,731
Additions based on tax positions related to the current year	11,042	15,982
(Deletions) Additions for tax positions of prior years	(766)	497
Balance at end of period	$ 113,486	$ 103,210

Equity Compensation Plans - Add

Equity Compensation Plans - Additional Information (Detail) - USD ($)	Sep. 28, 2017	Sep. 27, 2017	Dec. 31, 2017	Dec. 31, 2016
Stockholders Equity [Line Items]
Options outstanding			8,107,981	8,856,208
Share based awards, authorized			30,000,000
Board of Directors Chairman
Stockholders Equity [Line Items]
Contractual term of stock option awards, years		10 years
Options to purchase shares of common stock, percentage		100.00%
Independent Director | Common Stock
Stockholders Equity [Line Items]
Initial equity grant value		$ 550,000
Average closing price of common stock, trailing period		3 months
Additional equity grant value		$ 375,000
Stock Option | Board of Directors Chairman
Stockholders Equity [Line Items]
Percentage of share award allocation		50.00%
Stock Option | Independent Director | Common Stock
Stockholders Equity [Line Items]
Vesting period, years		3 years
Percentage of share award allocation		60.00%
Employee Stock Purchase Plan
Stockholders Equity [Line Items]
Shares reserved for future issuance			600,000
Options to purchase shares of common stock, percentage			85.00%
Span of offering period, in years			2 years
Maximum percentage of qualified compensation to be used for purchase			10.00%
Maximum payroll deductions			$ 25,000
Shares issued under the Employee Stock Purchase Plan			200,000
Share based awards, authorized			3,500,000
Unvested restricted stock units
Stockholders Equity [Line Items]
Vesting period, years		1 year
Unvested restricted stock units | Common Stock
Stockholders Equity [Line Items]
Vesting period, years		1 year
Unvested restricted stock units | Board of Directors Chairman
Stockholders Equity [Line Items]
Percentage of share award allocation		50.00%
Unvested restricted stock units | Independent Director
Stockholders Equity [Line Items]
Vesting period, years		3 years
Percentage of share award allocation		40.00%
Unvested restricted stock units | Independent Director | Common Stock
Stockholders Equity [Line Items]
Vesting period, years	1 year
Initial equity grant value	$ 375,000
Average closing price of common stock, trailing period	3 months
Share Incentive Plan
Stockholders Equity [Line Items]
Shares reserved for future issuance			10,900,000
Options outstanding			8,100,000
Share Incentive Plan | Stock Option
Stockholders Equity [Line Items]
Vesting period, years			4 years
Initial time period vesting requirements			12 months
Contractual term of stock option awards, years			10 years
Share Incentive Plan | Restricted Stock With Service Based Vesting Conditions
Stockholders Equity [Line Items]
Vesting period, years			4 years
Share Incentive Plan | Restricted Stock With Service Based Vesting Conditions | Board of Directors Chairman
Stockholders Equity [Line Items]
Vesting period, years			1 year

Summary of Stock Option Activit

Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Compensation Related Costs [Abstract]
Shares, Options outstanding as of December 31, 2016		8,856,208
Shares, Granted		801,170
Shares, Exercised		(1,367,307)
Shares, Expired and forfeited		(182,090)
Shares, Options outstanding as of December 31, 2017		8,107,981	8,856,208
Shares, Options unvested at December 31, 2017		1,462,941
Shares, Exercisable at December 31, 2017		6,645,032
Weighted Average Exercise Price, Outstanding as of December 31, 2016		$ 51.13
Weighted Average Exercise Price, Granted		87.74
Weighted Average Exercise Price, Exercised		34.96
Weighted Average Exercise Price, Expired and forfeited		92.98
Weighted Average Exercise Price, Outstanding as of December 31, 2017		56.53	$ 51.13
Weighted Average Exercise Price, Options unvested at December 31, 2017		88.19
Weighted Average Exercise Price, Exercisable at December 31, 2017		$ 49.56
Weighted Average Remaining Years, Options outstanding		5 years 1 month 6 days	5 years 4 months 24 days
Weighted Average Remaining Years, Options unvested at December 31, 2017		8 years 6 months
Weighted Average Remaining Years, Exercisable at December 31, 2017		4 years 3 months 18 days
Aggregate Intrinsic Value, Options outstanding	[1]	$ 281,141	$ 304,356
Aggregate Intrinsic Value, Options unvested at December 31, 2017	[1]	6,313
Aggregate Intrinsic Value, Exercisable at December 31, 2017	[1]	$ 274,828
[1]	The aggregate intrinsic value for outstanding options is calculated as the difference between the exercise price of the underlying awards and the quoted price of the Company’s common stock on the Nasdaq Global Select Market as of the last trading day for the respective year. The aggregate intrinsic value of options outstanding and exercisable includes options with an exercise price below $89.17, the closing price of the Company’s common stock on the Nasdaq Global Select Market on December 29, 2017, the last trading day of the year.

Summary of Stock Option Activ92

Summary of Stock Option Activity (Parenthetical) (Detail)	Dec. 29, 2017$ / shares
Compensation Related Costs [Abstract]
Closing price of common stock	$ 89.17

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value per option granted			$ 36.07	$ 40.70	$ 56.76
Total intrinsic value of options exercised			$ 77,000	$ 127,400	$ 146,600
Options in-the-money			7,400,000
Recognized compensation costs			$ 140,263	134,641	111,525
Net tax benefit from stock options exercised			7,800
Stock-based compensation capitalized to inventory			16,100	11,400	11,100
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation costs			36,700	45,500	41,500
Unrecognized compensation cost related to unvested awards			$ 49,200
Unrecognized compensation cost expected to recognized over weighted average period, in years			2 years 4 months 24 days
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation costs			$ 11,700	10,100	7,100
Unrecognized compensation cost related to unvested awards			$ 12,900
Unrecognized compensation cost expected to recognized over weighted average period, in years			1 year 4 months 24 days
Restricted Stock With Service Based Vesting Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation costs			$ 86,500	$ 74,700	$ 47,900
Unrecognized compensation cost related to unvested awards			$ 173,700
Unrecognized compensation cost expected to recognized over weighted average period, in years			1 year 3 months 18 days
Weighted-average fair value per RSU granted			$ 87.88	$ 84.18	$ 119.86
The total fair value of restricted stock vested and released			$ 76,500	$ 63,500	$ 59,500
Granted restricted stock units			2,679,534	2,444,966
2017 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation costs			$ 4,141	$ 0	0
Weighted-average fair value per RSU granted	$ 87.42
Granted restricted stock units	133,250
Percentage of threshold achievement	75.00%
Percentage of ceiling achievement	125.00%
Award vesting service period	3 years
2017 Base Restricted Stock Unit Awards with Performance Conditions | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of, number of shares may earned	50.00%
2017 Base Restricted Stock Unit Awards with Performance Conditions | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of, number of shares may earned	200.00%
2015 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recognized compensation costs			2,291	$ 2,342	$ 1,805
Unrecognized compensation cost related to unvested awards			$ 12,400
Weighted-average fair value per RSU granted		$ 108.36
Granted restricted stock units		58,300
Award vesting service period		3 years	1 year 9 months 18 days

Assumptions Used to Estimate Pe

Assumptions Used to Estimate Per Share Fair Value of Stock Options Granted (Detail) - Stock Option	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	38.00%	36.00%	36.00%
Expected volatility, maximum	40.00%	44.00%	45.00%
Dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate, minimum	1.80%	1.10%	1.50%
Risk-free interest rate, maximum	2.20%	2.30%	2.20%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	4 years 10 months 24 days	5 years	6 years 4 months 24 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	6 years 7 months 6 days	8 years 1 month 6 days	8 years

Assumptions Used to Estimate 95

Assumptions Used to Estimate Per Share Fair Value of Stock Purchase Rights Granted (Detail) - Employee Stock Purchase Plan	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	28.00%	42.00%	36.00%
Expected volatility, maximum	42.00%	50.00%	38.00%
Dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate, minimum	1.00%	0.40%	0.10%
Risk-free interest rate, maximum	1.60%	0.80%	0.80%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	6 months	6 months	6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	24 months	24 months	24 months

Summary of Restricted Stock Uni

Summary of Restricted Stock Unit Activity (Detail) - Restricted Stock With Service Based Vesting Conditions - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Share based Compensation Arrangements by Share based Payment Award, Equity Instruments, Other Than Options, Restricted Stock Units [Line Items]
Shares, Non-vested units as of December 31, 2016	2,444,966
Shares, Granted	1,382,900
Shares, Vested	(837,926)
Shares, Forfeited	(310,406)
Shares, Non-vested units as of December 31, 2017	2,679,534	2,444,966
Weighted Average Grant Date Fair Value, Non-vested units as of December 31, 2016	$ 92.70
Weighted Average Grant Date Fair Value, Granted	87.88	$ 84.18	$ 119.86
Weighted Average Grant Date Fair Value, Vested	92
Weighted Average Grant Date Fair Value, Forfeited	96.02
Weighted Average Grant Date Fair Value, Non-vested units as of December 31, 2017	$ 90.04	$ 92.70
Weighted Average Remaining Years, Non-vested units	1 year 4 months 24 days	1 year 4 months 24 days
Aggregate Intrinsic Value, Non-vested units	$ 238,934	$ 202,541

Summary of Restricted Stock U97

Summary of Restricted Stock Unit Awards with Performance Conditions (Detail) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Mar. 31, 2017$ / sharesshares	Mar. 31, 2016$ / sharesshares	Mar. 31, 2015$ / sharesshares	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Expense | $				$ 140,263	$ 134,641	$ 111,525
March 2017 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Base RSUs Granted	133,250
Grant Date Fair Value per RSU | $ / shares	$ 87.42
Multiplier Achieved	103
RSUs Earned	131,651
Compensation Expense | $				4,141	0	0
March 2016 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Base RSUs Granted		130,310
Grant Date Fair Value per RSU | $ / shares		$ 83.43
Multiplier Achieved		103
RSUs Earned		134,219
Compensation Expense | $				3,928	2,956	0
March 2015 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Base RSUs Granted			58,300
Grant Date Fair Value per RSU | $ / shares			$ 108.36
Multiplier Achieved			111
RSUs Earned			64,713
Compensation Expense | $				$ 2,291	$ 2,342	$ 1,805

Summary of Restricted Stock U98

Summary of Restricted Stock Unit Awards with Performance Conditions (Parenthetical) (Detail)	1 Months Ended			12 Months Ended
	Mar. 31, 2017shares	Mar. 31, 2016shares	Mar. 31, 2015shares	Dec. 31, 2017
March 2017 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Multiplier Achieved	103
RSUs Earned	131,651
Award vesting service period	3 years
March 2016 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Multiplier Achieved		103
RSUs Earned		134,219
Award vesting service period		3 years
March 2015 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Multiplier Achieved			111
RSUs Earned			64,713
Award vesting service period			3 years	1 year 9 months 18 days

Compensation Expense (Detail)

Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 140,263	$ 134,641	$ 111,525
Cost of Sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	10,636	9,121	6,836
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	53,112	58,279	49,399
Selling, General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 76,515	$ 67,241	$ 55,290

Amounts Reclassified out of Acc

Amounts Reclassified out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net product revenues	$ 1,270,445	$ 1,110,381	$ 884,522
Selling, general and administrative	554,336	476,593	402,271
LOSS FROM OPERATIONS	(14,700)	(803,429)	(110,702)
Other income (expense)	7,970	4,929	(9,462)
Provision for (benefit from) income taxes	81,167	(200,840)	17,075
NET LOSS	(117,042)	(630,210)	$ (171,799)
Amount Reclassified from AOCI (Gain) Loss
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Provision for (benefit from) income taxes	1,191	42
NET LOSS	(3,052)	10,116
Amount Reclassified from AOCI (Gain) Loss | Gains (losses) on Cash Flow Hedges
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
LOSS FROM OPERATIONS	(5,113)	10,273
Amount Reclassified from AOCI (Gain) Loss | Gains (losses) on Cash Flow Hedges | Forward Foreign Currency Exchange Contracts
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net product revenues	(5,377)	6,112
Selling, general and administrative	264	4,161
Amount Reclassified from AOCI (Gain) Loss | Gain (Loss) on Sale of Available-for-Sale Debt Securities
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)	$ 3,252	$ (115)

Summary of Changes in Accumulat

Summary of Changes in Accumulated Balances of Other Comprehensive Loss Including Current Period Reclassifications Out of AOCI and Other Amount of Current Period Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 2,766,275	$ 2,400,847
Other comprehensive income (loss) before reclassifications	(39,101)	(2,429)
Less: net gain (loss) reclassified from AOCI	(1,861)	10,158
Tax effect	1,463	4,370
Net current-period other comprehensive income (loss)	(35,777)	(8,217)
Ending Balance	2,808,663	2,766,275
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	13,006	13,602
Other comprehensive income (loss) before reclassifications	(38,351)	9,677
Less: net gain (loss) reclassified from AOCI	(5,113)	10,273
Tax effect	0	0
Net current-period other comprehensive income (loss)	(33,238)	(596)
Ending Balance	(20,232)	13,006
Unrealized Gains on Available-for-Sale Debt Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(178)	7,441
Other comprehensive income (loss) before reclassifications	(755)	(12,104)
Less: net gain (loss) reclassified from AOCI	3,252	(115)
Tax effect	1,463	4,370
Net current-period other comprehensive income (loss)	(2,544)	(7,619)
Ending Balance	(2,722)	(178)
Foreign Currency Items
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(12)	(10)
Other comprehensive income (loss) before reclassifications	5	(2)
Tax effect	0	0
Net current-period other comprehensive income (loss)	5	(2)
Ending Balance	(7)	(12)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	12,816	21,033
Ending Balance	$ (22,961)	$ 12,816

Revenue and Credit Concentra102

Revenue and Credit Concentrations - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Customer	Dec. 31, 2016USD ($)Customer	Dec. 31, 2015
Concentration Risk [Line Items]
Accounts receivable, net	$ 261,365	$ 215,280
Largest Customers
Concentration Risk [Line Items]
Accounts receivable, net	$ 18,100	$ 30,700
Accounts Receivable | Largest Customers
Concentration Risk [Line Items]
Number of customers accounted for largest balance in accounts receivable | Customer	2	2
Geographic Concentration Risk | Net Product Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	93.00%	92.00%	89.00%
Geographic Concentration Risk | Net Product Revenue | Minimum
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%
Credit Concentration Risk | Net Product Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%
Credit Concentration Risk | Accounts Receivable | Larger Customer One
Concentration Risk [Line Items]
Concentration risk, percentage	21.00%	26.00%
Credit Concentration Risk | Accounts Receivable | Larger Customer Two
Concentration Risk [Line Items]
Concentration risk, percentage	18.00%	20.00%

Consolidated Net Product Revenu

Consolidated Net Product Revenue Concentrations Based on Patient Location (Detail) - Net Product Revenue	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	93.00%	92.00%	89.00%
Geographic Concentration Risk | United States
Concentration Risk [Line Items]
Concentration risk, percentage	39.00%	37.00%	39.00%
Geographic Concentration Risk | Europe
Concentration Risk [Line Items]
Concentration risk, percentage	21.00%	23.00%	19.00%
Geographic Concentration Risk | Latin America
Concentration Risk [Line Items]
Concentration risk, percentage	14.00%	13.00%	16.00%
Geographic Concentration Risk | Rest of World
Concentration Risk [Line Items]
Concentration risk, percentage	19.00%	19.00%	15.00%
Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	56.00%	56.00%	49.00%
Customer Concentration Risk | Genzyme | Aldurazyme
Concentration Risk [Line Items]
Concentration risk, percentage	7.00%	8.00%	11.00%
Credit Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%

Consolidated Net Product Rev104

Consolidated Net Product Revenue Concentrations Attributed to Largest Customers (Detail) - Customer Concentration Risk - Net Product Revenue	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Concentration Risk [Line Items]
Concentration risk, percentage	56.00%	56.00%	49.00%
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	18.00%	19.00%	15.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	14.00%	13.00%	13.00%
Customer C
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%	10.00%	0.00%
Customer D
Concentration Risk [Line Items]
Concentration risk, percentage	7.00%	8.00%	11.00%
Customer E
Concentration Risk [Line Items]
Concentration risk, percentage	7.00%	6.00%	10.00%

Segment and Geographic Infor105

Segment and Geographic Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017Segment
Segment Reporting [Abstract]
Number of operating business segment	1

Segment and Geographic Infor106

Segment and Geographic Information by Product Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue from External Customer [Line Items]
Net product revenues	$ 1,270,445	$ 1,110,381	$ 884,522
Vimizim
Revenue from External Customer [Line Items]
Net product revenues	413,251	354,058	228,147
Brineura
Revenue from External Customer [Line Items]
Net product revenues	8,595	0	0
Naglazyme
Revenue from External Customer [Line Items]
Net product revenues	332,208	296,537	303,090
Kuvan
Revenue from External Customer [Line Items]
Net product revenues	407,542	348,009	239,336
Aldurazyme
Revenue from External Customer [Line Items]
Net product revenues	89,959	93,749	97,912
Firdapse
Revenue from External Customer [Line Items]
Net product revenues	$ 18,890	$ 18,028	$ 16,037

Summary of Total Revenues from

Summary of Total Revenues from External Customers and Collaborative Partners by Geographic Region (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue from External Customer [Line Items]
Total revenues	$ 1,313,646	$ 1,116,854	$ 889,895
United States
Revenue from External Customer [Line Items]
Total revenues	588,243	507,539	444,075
Europe
Revenue from External Customer [Line Items]
Total revenues	301,487	252,633	171,216
Latin America
Revenue from External Customer [Line Items]
Total revenues	182,438	147,471	142,305
Rest of World
Revenue from External Customer [Line Items]
Total revenues	$ 241,478	$ 209,211	$ 132,299

Summary of Non-Monetary Long-Li

Summary of Non-Monetary Long-Lived Assets by Geographic Region (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Revenue from External Customer [Line Items]
Total long-lived assets	$ 2,010,142	$ 1,999,339
United States
Revenue from External Customer [Line Items]
Total long-lived assets	1,183,791	1,183,938
Europe
Revenue from External Customer [Line Items]
Total long-lived assets	823,657	812,833
Rest of World
Revenue from External Customer [Line Items]
Total long-lived assets	$ 2,694	$ 2,568

Collaboration and License Ag109

Collaboration and License Agreements - Additional Information (Detail) - USD ($)	Oct. 06, 2015	Jul. 31, 2017	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2012	Sep. 30, 2016	Oct. 31, 2012
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Termination of collaborative agreement prior to written notice in number of days				90 days
Net gain on sale of intangible assets				$ 125,000,000	$ 0	$ 369,498,000
Royalties on net product sales									7.00%
Royalties on net product sales									10.00%
Talazoparib
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Net gain on sale of intangible assets			$ 369,500,000
Medivation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment received	$ 410,000,000
Milestone payments								$ 160,000,000
Catalyst Pharmaceutical Partners, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Licensing arrangement, convertible promissory note received							$ 5,000,000
Licensing arrangement, shares received upon conversion promissory note							6,700,000
Accounts receivable				$ 0
Common stock shares held				0
Sarepta Therapeutics | License Agreement And Settlement Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
License revenue		$ 35,000,000
Sarepta Therapeutics | United States | License Agreement And Settlement Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalties receivable percentage of net sales		5.00%
Sarepta Therapeutics | EU and Other Countries | License Agreement And Settlement Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalties receivable percentage of net sales		8.00%

Compensation Agreements and 110

Compensation Agreements and Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Compensation And Retirement Disclosure [Line Items]
Gain (loss) in fair value of restricted stock issued	$ (1,400,000)	$ 5,000,000	$ 2,500,000
BioMarin Retirement Savings Plan
Compensation And Retirement Disclosure [Line Items]
Employee contribution of their current compensation	100.00%
Company's contribution to match employees contribution	100.00%
Employer contribution of maximum percentage over employee's annual compensation	6.00%
Employer contribution over employee's annual compensation	$ 14,000
Employer contribution over employee's annual compensation starting next fiscal year	$ 16,000
Company's savings plan contribution vesting period, years	4 years
Company's contribution from employment commencement	$ 19,800,000	16,000,000	$ 15,100,000
Deferred Compensation Plan
Compensation And Retirement Disclosure [Line Items]
Fair value of company stock held	$ 19,600,000	$ 19,400,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Thousands, € in Millions	12 Months Ended
	Dec. 31, 2017USD ($)LawsuitCase$ / €	Dec. 31, 2017EUR (€)LawsuitCase	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Commitments and Contingencies [Line Items]
Lease expiration date	2,026	2,026
Lease extension option, renewal period	5 years	5 years
Rent expense	$ 11,400		$ 11,600	$ 9,300
Deferred rent accruals	2,300		2,400
Deferred rent accruals, current	2,000		2,000
Purchase commitment for the next five years	$ 52,800
Number of lawsuits alleging patent infringement filed | Lawsuit	2	2
Number of cases Consolidated | Case	2	2
Contingent payments upon achievement of development and regulatory activities and commercial sales and licensing milestones	$ 604,600
Contingent consideration payable	189,000
Short-term contingent acquisition consideration payable	53,648		$ 46,327
Merck Serono
Commitments and Contingencies [Line Items]
Contingent payments upon achievement of development and regulatory activities and commercial sales and licensing milestones	$ 222,000	€ 185
Currency exchange translation rate | $ / €	1.20
Completed Programs
Commitments and Contingencies [Line Items]
Contingent payments upon achievement of development and regulatory activities and commercial sales and licensing milestones	$ 53,400

Minimum Lease Payments for Futu

Minimum Lease Payments for Future Years (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,018	$ 9,697
2,019	7,671
2,020	5,996
2,021	4,948
2,022	3,961
Thereafter	5,851
Total	$ 38,124