BioMarin Pharmaceutical (BMRN) 10-Q 3 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 23, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	BMRN
Entity Registrant Name	BIOMARIN PHARMACEUTICAL INC
Entity Central Index Key	1,048,477
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		177,590,376

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	[1]
Current assets:
Cash and cash equivalents	$ 427,411	$ 598,028
Short-term investments	935,662	797,940
Accounts receivable, net	363,566	261,365
Inventory	473,356	475,775
Other current assets	80,072	74,036
Total current assets	2,280,067	2,207,144
Noncurrent assets:
Long-term investments	279,988	385,785
Property, plant and equipment, net	900,480	896,700
Intangible assets, net	502,295	517,510
Goodwill	197,039	197,039
Deferred tax assets	425,380	399,095
Other assets	39,430	29,852
Total assets	4,624,679	4,633,125
Current liabilities:
Accounts payable and accrued liabilities	358,732	401,921
Short-term convertible debt, net	369,752	360,949
Short-term contingent acquisition consideration	76,466	53,648
Total current liabilities	804,950	816,518
Noncurrent liabilities:
Long-term convertible debt, net	821,871	813,521
Long-term contingent acquisition consideration	57,674	135,318
Other long-term liabilities	55,080	59,105
Total liabilities	1,739,575	1,824,462
Stockholders’ equity:
Common stock, $0.001 par value: 500,000,000 shares authorized; 177,508,135 and 175,843,749 shares issued and outstanding, respectively.	178	176
Additional paid-in capital	4,577,300	4,483,220
Company common stock held by Nonqualified Deferred Compensation Plan (the NQDC)	(13,390)	(14,224)
Accumulated other comprehensive loss	(1,129)	(22,961)
Accumulated deficit	(1,677,855)	(1,637,548)
Total stockholders’ equity	2,885,104	2,808,663
Total liabilities and stockholders’ equity	$ 4,624,679	$ 4,633,125
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017	[1]
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	177,508,135	175,843,749
Common stock, shares outstanding	177,508,135	175,843,749
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
REVENUES:
Total revenues	$ 372,845	$ 317,448	$ 746,292	$ 621,193
OPERATING EXPENSES:
Cost of sales	79,019	56,305	161,352	106,311
Research and development	175,582	143,039	359,530	288,042
Selling, general and administrative	153,280	143,505	291,616	263,524
Intangible asset amortization and contingent consideration	10,227	13,411	23,429	22,336
Gain on sale of intangible assets	20,000	0	20,000	0
Total operating expenses	398,108	356,260	815,927	680,213
LOSS FROM OPERATIONS	(25,263)	(38,812)	(69,635)	(59,020)
Equity in the loss of BioMarin/Genzyme LLC	(107)	(220)	(39)	(743)
Interest income	5,569	2,983	10,803	6,055
Interest expense	(12,225)	(10,040)	(23,787)	(20,159)
Other income, net	2,849	543	2,677	4,015
LOSS BEFORE INCOME TAXES	(29,177)	(45,546)	(79,981)	(69,852)
Benefit from income taxes	(12,385)	(8,713)	(19,040)	(16,729)
NET LOSS	$ (16,792)	$ (36,833)	$ (60,941)	$ (53,123)
NET LOSS PER SHARE, BASIC AND DILUTED	$ (0.09)	$ (0.21)	$ (0.35)	$ (0.31)
Weighted average common shares outstanding, basic and diluted	176,873	174,374	176,405	173,547
COMPREHENSIVE INCOME (LOSS)	$ 10,624	$ (56,511)	$ (38,523)	$ (80,597)
Net Product Revenues
REVENUES:
Total revenues	367,786	315,926	736,885	618,116
Royalty and Other Revenues
REVENUES:
Total revenues	$ 5,059	$ 1,522	$ 9,407	$ 3,077

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands		Total		Common Stock	Additional Paid-in Capital	Company Common Stock Held By The NQDC	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance at Dec. 31, 2016							$ 12,816
Net loss		$ (53,123)
Ending Balance at Jun. 30, 2017							(14,658)
Beginning Balance at Mar. 31, 2017							5,020
Net loss		(36,833)
Ending Balance at Jun. 30, 2017							(14,658)
Beginning Balance at Dec. 31, 2017		2,808,663	[1]	$ 176	$ 4,483,220	$ (14,224)	(22,961)	$ (1,637,548)
Beginning Balance (in shares) at Dec. 31, 2017				175,844
Impact of change in accounting principle at Dec. 31, 2017	[2]						(586)
Impact of change in accounting principle (ASC 606) at Dec. 31, 2017		20,048						20,048
Impact of change in accounting principle (ASU 2018-02) at Dec. 31, 2017							(586)	586
Adjusted balance at January 1, 2018 at Dec. 31, 2017		2,828,711		$ 176	4,483,220	(14,224)	(23,547)	(1,616,914)
Net loss		(60,941)						(60,941)
Other comprehensive income		22,418					22,418
Issuances under equity incentive plans, net of tax		16,312		$ 2	16,310
Issuances under equity incentive plans, net of tax (in share)				1,664
Common stock held by the NQDC		834				834
Stock-based compensation		77,770			77,770
Ending Balance at Jun. 30, 2018		2,885,104		$ 178	4,577,300	(13,390)	(1,129)	(1,677,855)
Ending Balance (in shares) at Jun. 30, 2018				177,508
Beginning Balance at Mar. 31, 2018							(28,545)
Net loss		(16,792)
Ending Balance at Jun. 30, 2018		$ 2,885,104		$ 178	$ 4,577,300	$ (13,390)	$ (1,129)	$ (1,677,855)
Ending Balance (in shares) at Jun. 30, 2018				177,508
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.
[2]	As of January 1, 2018, the Company early adopted the requirements of ASU 2018-02. The amount represents the reclassification from Accumulated Other Comprehensive Income (Loss) to Accumulated Deficit in the first quarter of 2018 related to the adoption of ASU 2018-02. See Note 4 for additional discussion

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (60,941)		$ (53,123)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	44,610		38,497
Non-cash interest expense	17,300		15,601
Accretion of discount on investments	(41)		1,327
Stock-based compensation	75,214		70,775
Gain on sale of intangible assets	(20,000)		0
Gain on the sale of equity investments	0		(3,252)
Deferred income taxes	(29,681)		(22,770)
Unrealized foreign exchange gain	(5,693)		(4,870)
Non-cash changes in the fair value of contingent acquisition consideration	1,828		7,195
Other	1,772		3,806
Changes in operating assets and liabilities:
Accounts receivable, net	(77,416)		(16,834)
Inventory	15,493		(60,369)
Other current assets	(2,037)		(3,710)
Other assets	(6,448)		(1,109)
Accounts payable and accrued liabilities	(32,989)		(36,286)
Other long-term liabilities	2,663		3,459
Net cash used in operating activities	(76,366)		(61,663)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant and equipment	(52,682)		(116,847)
Maturities and sales of investments	311,969		234,617
Purchases of available-for-sale securities	(345,458)		(130,986)
Proceeds from sale of intangible asset	20,000		0
Other	(841)		(1,560)
Net cash used in investing activities	(67,012)		(14,776)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercises of awards under equity incentive plans	44,926		40,659
Taxes paid related to net share settlement of equity awards	(28,614)		(26,624)
Payment of contingent acquisition consideration	(43,108)		(1,894)
Other	0		(28)
Net cash (used in) provided by financing activities	(26,796)		12,113
Effect of exchange rate changes on cash	(443)		10,860
NET DECREASE IN CASH AND CASH EQUIVALENTS	(170,617)		(53,466)
Cash and cash equivalents:
Beginning of period	598,028	[1]	408,330
End of period	427,411		354,864
SUPPLEMENTAL CASH FLOW DISCLOSURES:
Cash paid for income taxes	14,858		16,341
Cash paid for interest, net of interest capitalized into fixed assets	5,831		4,519
SUPPLEMENTAL CASH FLOW DISCLOSURES FOR NON CASH INVESTING AND FINANCING ACTIVITIES:
Decrease in accounts payable and accrued liabilities related to fixed assets	(7,734)		(29,300)
Conversion of convertible debt	$ 0		$ 22,477
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.

NATURE OF OPERATIONS

NATURE OF OPERATIONS	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
NATURE OF OPERATIONS	(1) NATURE OF OPERATIONS BioMarin Pharmaceutical Inc. (the Company) is a global biotechnology company that develops and commercializes innovative therapies for people with serious and life-threatening rare diseases and medical conditions. The Company selects product candidates for diseases and conditions that represent a significant unmet medical need, have well-understood biology and provide an opportunity to be first-to-market or offer a significant benefit over existing products. The Company’s therapy portfolio consists of seven commercial products and multiple clinical and pre-clinical product candidates. Palynziq (formerly known as pegvaliase) was granted marketing approval in the United States (U.S.) on May 24, 2018. The Company expects to continue to finance future cash needs that exceed its operating activities primarily through its current cash, cash equivalents and investments and through proceeds from debt or equity offerings, commercial borrowing, or through collaborative agreements with corporate partners. If the Company elects to increase its spending on development programs significantly above current long-term plans or enters into potential licenses and other acquisitions of complementary technologies, products or companies, the Company may need additional capital.

BASIS OF PRESENTATION

BASIS OF PRESENTATION	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
BASIS OF PRESENTATION	(2) BASIS OF PRESENTATION The accompanying Condensed Consolidated Financial Statements have been prepared pursuant to U.S. generally accepted accounting principles (U.S. GAAP) and the rules and regulations of the SEC for Quarterly Reports on Form 10-Q and do not include all of the information and note disclosures required by U.S. GAAP for complete financial statements, although the Company believes that the disclosures herein are adequate to ensure that the information presented is not misleading. The Condensed Consolidated Financial Statements should therefore be read in conjunction with the Consolidated Financial Statements and Notes thereto for the fiscal year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K. Effective January 1, 2018, the Company adopted the requirements of Accounting Standards Codification 606, Revenue from Contracts with Customers Significant Accounting Policies U.S. GAAP requires management to make estimates and assumptions that affect amounts reported in the Condensed Consolidated Financial Statements and accompanying disclosures. Although these estimates are based on management’s best knowledge of current events and actions that the Company may undertake in the future, actual results may be different from those estimates. The Condensed Consolidated Financial Statements reflect all adjustments of a normal, recurring nature that are, in the opinion of management, necessary for a fair presentation of results for these interim periods. The results of operations for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2018 or any other period. Management performed an evaluation of the Company’s activities through the date of filing of this Quarterly Report on Form 10-Q, and has concluded that there were no subsequent events or transactions that occurred subsequent to the balance sheet date prior to filing this Quarterly Report on Form 10-Q that would require recognition or disclosure in the Condensed Consolidated Financial Statements.

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES	(3) SIGNIFICANT ACCOUNTING POLICIES Except as detailed below, there have been no material changes to the Company’s significant accounting policies during the six months ended June 30, 2018, as compared to the significant accounting policies disclosed in Note 3 of the Consolidated Financial Statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017. Effective January 1, 2018, the Company adopted the provisions of ASC 606 using the modified retrospective method for all contracts not completed as of the date of adoption. For contracts that were modified before the effective date, the Company reflected the aggregate effect of all modifications when identifying performance obligations and allocating transaction price in accordance with available practical expedients. The reported results for 2018 reflect the application of ASC 606 guidance, while the reported results for 2017 were prepared under the guidance of ASC 605, Revenue Recognition Under ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that are within the scope of ASC 606, the Company performs the following five steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer, and is the unit of account in ASC 606. 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. 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. Revenues from product sales are recognized when the customer obtains control of the Company’s product, which occurs at a point in time, typically upon shipment to the customer. Amounts collected from customers and remitted to governmental authorities, which primarily consist of value-added taxes related to product sales in foreign jurisdictions, are presented on a net basis in the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss), in that taxes billed to customers are not included as a component of Net Product Revenues. For Aldurazyme revenues, the Company receives a payment ranging from 39.5% to 50% on worldwide net Aldurazyme sales by Genzyme Corporation (Genzyme) depending on sales volume, which is included in Net Product Revenues in the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss). Under the previous guidance the Company only recognized a portion of this amount as product transfer revenue when the product was released to Genzyme because all of the Company’s performance obligations were fulfilled at that point, the prices were substantially fixed or determinable and title to, and risk of loss for, the product had transferred to Genzyme. The product transfer revenue only represented the fixed amount per unit of Aldurazyme that Genzyme was required to pay the Company if the product was unsold by Genzyme. The amount of product transfer revenue was eventually deducted from the calculated royalty recognized when the product was subsequently sold by Genzyme. The Company recorded the Aldurazyme revenues based on net sales information provided by Genzyme and recorded product transfer revenues based on the fulfillment of Genzyme purchase orders in accordance with the terms of the related agreements with Genzyme. Under ASC 606, the Company recognizes its best estimate of the entire revenue that it expects to receive when the product is released and control is transferred to Genzyme. The Company records Aldurazyme net product revenues based on the estimated variable consideration payable when the product is sold through by Genzyme. Actual amounts of consideration ultimately received may differ from the Company’s estimates, however the Company does not expect any such difference to be material. If actual results in the future vary from the Company’s estimates, the Company will make adjustments, which would affect Net Product Revenues and earnings in the period such variances become known. Revenue Reserves Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration for which reserves are established and which result from government rebates, sales returns, and other incentives that are offered within contracts between the Company and its customers, as such specialty pharmacies, hospitals, authorized distributors and government purchasers. These reserves are based on the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable (if the amount is payable to the customer) or a current liability (if the amount is payable to a party other than a customer). Where appropriate, these estimates take into consideration a range of possible outcomes which are probability-weighted for relevant factors such as the Company’s historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained, and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust its estimates, which would affect net product revenue and earnings in the period such variances become known. Government Rebates : The Company records reserves for rebates payable under Medicaid and other government programs as a reduction of revenue at the time product revenues are recorded. The Company’s reserve calculations require estimates, including estimates of customer mix, to determine which sales will be subject to rebates and the amount of such rebates. The Company updates its estimates and assumptions on a quarterly basis and records any necessary adjustments to its reserves. Sales Returns : The Company records allowances for product returns, if appropriate, as a reduction of revenue at the time product sales are recorded. 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 historical 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. The Company relies on historical return rates to estimate returns. 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. Other Incentives : Other incentives include fees paid to the Company’s distributors, discounts for prompt payment and the estimated costs of the Company’s patient co-payment assistance programs. Beginning in 2018, the Company also offers a branded co-pay assistance program for eligible patients with commercial insurance in the U.S. who are on Kuvan or Brineura therapy. The branded co-pay assistance programs assist commercially insured patients who have coverage for Kuvan or Brineura and are intended to reduce each participating patient’s portion of the financial responsibility for Kuvan’s or Brineura’s purchase price up to a specified dollar amount of assistance. The Company records fees paid to distributors, cash discounts and amounts paid under the branded specific co-pay assistance program for each patient as a reduction of revenue. Royalty and Other Revenues Royalties : For arrangements that include the receipt of sales-based royalties, including milestone payments based on the level of sales when the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (a) when the related sales occur, or (b) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone payments : At the inception of each arrangement that includes developmental, regulatory or commercial milestone payments, the Company evaluates whether achieving the milestones is considered probable and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated milestone (such as a regulatory submission by the Company) is included in the transaction price. Milestone payments that are not within the control of the Company, such as approvals from regulators or where attainment of the specified event is dependent on the development activities of a third-party, are not considered probable of being achieved until those approvals are received or the specified event occurs. Revenue is recognized from the satisfaction of performance obligations in the amount billable to the customer .

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	6 Months Ended
	Jun. 30, 2018
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	(4) RECENT ACCOUNTING PRONOUNCEMENTS Except as described below, there have been no new accounting pronouncements or changes to accounting pronouncements during the six months ended June 30, 2018, as compared to the recent accounting pronouncements described in Note 4 of the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, that the Company believes are of significance or potential significance to the Company. Accounting Pronouncements Not Yet Adopted In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-02, Leases As of June 30, 2018, 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 Condensed 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 Condensed Consolidated Balance Sheets due to the requirement to recognize lease ROU assets and corresponding liabilities related to leases on the Company’s Condensed Consolidated Balance Sheets, however it is not anticipated to have a material impact on the Company’s other Condensed Consolidated Financial Statements. Accounting Pronouncements Adopted Effective January 1, 2018, the Company adopted ASC 606, which provides principles for recognizing revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. The Company adopted ASC 606 on a modified retrospective basis through a cumulative adjustment to equity. See Note 3 – Significant Accounting Policies Revenue, Credit Concentrations and Geographic Information The cumulative effect of applying the new guidance of ASC 606 As Reported Adjusted December 31, 2017 Aldurazyme (1) Tax Provision (2) January 1, 2018 Balance Sheet Assets: Accounts receivable, net $ 261,365 $ 26,012 $ — $ 287,377 Deferred tax assets $ 399,095 $ — $ (5,964 ) $ 393,131 Total assets $ 4,633,125 $ 26,012 $ (5,964 ) $ 4,653,173 Equity: Accumulated deficit $ (1,637,548 ) $ 26,012 $ (5,964 ) $ (1,617,500 ) Total liabilities and stockholders' equity $ 4,633,125 $ 26,012 $ (5,964 ) $ 4,653,173 (1) This adjustment represents management’s estimate of the variable consideration to be earned on worldwide sales of Aldurazyme by Genzyme in excess of the product transfer revenue previously recognized for Genzyme’s ending inventory at December 31, 2017. The product transfer revenue previously recognized as revenue represents the fixed amount per unit of Aldurazyme that Genzyme was required to pay the Company if the product was unsold by Genzyme. (2) The adoption of ASC 606 primarily resulted in an acceleration of the variable consideration components of revenue as of December 31, 2017, which in turn generated additional deferred tax liabilities that ultimately reduced the Company's net deferred tax asset position. The tax provision amount has been calculated using the Company’s estimated statutory rate. The impact of adoption on the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for the three and six months ended June 30, 2018 was as follows: Three Months Ended June 30, 2018 Balance without Adoption of As Reported Adjustments (1) ASC 606 Net product revenues $ 367,786 $ 48 $ 367,834 Benefit from income taxes $ (12,385 ) $ 11 $ (12,374 ) Net loss $ (16,792 ) $ 37 $ (16,755 ) Six Months Ended June 30, 2018 Balance without Adoption of As Reported Adjustments (1) ASC 606 Net product revenues $ 736,885 $ (27,150 ) $ 709,735 Benefit from income taxes $ (19,040 ) $ (6,225 ) $ (25,265 ) Net loss $ (60,941 ) $ (20,925 ) $ (81,866 ) (1) The adoption of ASC 606 resulted in additional revenues recognized in the first half of 2018, which in turn generated additional deferred tax liabilities that reduced the Company's benefit from income taxes. The Benefit from Income Taxes amount has been calculated using the Company’s estimated statutory rate. The impact of adoption on the Company’s Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2018 was as follows: Balance without Adoption of As Reported Adjustments (1) ASC 606 Net loss $ (60,941 ) $ (20,925 ) $ (81,866 ) Deferred income taxes $ (29,681 ) $ (6,225 ) $ (35,906 ) Changes in operating assets and liabilities: Accounts receivable, net $ (77,416 ) $ 27,150 $ (50,266 ) Net cash used in operating activities $ (76,366 ) $ — $ (76,366 ) (1) The adoption of ASC 606 resulted in decreased Net Loss and increased Accounts Receivable, Net due to additional revenues recognized in the first quarter of 2018, which in turn generated additional deferred tax liabilities that reduced the Company's net Deferred Tax Assets. The Deferred Income Taxes amount has been calculated using the Company’s estimated statutory rate. In February 2018, the FASB issued ASU No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

NET LOSS PER COMMON SHARE

NET LOSS PER COMMON SHARE	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
NET LOSS PER COMMON SHARE	(5) 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 Employee Stock Purchase Plan (ESPP), unvested restricted stock units (RSUs), common stock held by the NQDC and contingent issuances of common stock related to convertible debt. 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 of common shares): Three and Six Months Ended June 30, 2018 2017 Options to purchase common stock 7,829 8,440 Common stock issuable under the 2018 Notes 3,983 3,983 Common stock issuable under the 2020 Notes 3,983 3,983 Common stock issuable under the 2024 Notes 3,970 — Unvested restricted stock units 3,544 3,041 Common stock potentially issuable for ESPP purchases 433 387 Common stock held by the NQDC 208 224 Total number of potentially issuable shares 23,950 20,058 In connection with the issuance of to the Company’s 0.75% senior subordinated convertible notes due in 2018 (the 2018 Notes) and the Company’s 1.50% senior subordinated convertible notes due in 2020 (the 2020 Notes), the Company entered into capped call transactions with respect to 50% of the principal amount of the 2018 Notes and 50% of the principal amount of the 2020 Notes with certain hedge counterparties with conversion price of $94.15 per share. Although the Company’s stock price on June 29, 2018 (the last trading day before June 30, 2018) exceeded the conversion price, the potential effect of the capped call transactions and potential shares issuable under the 2018 Notes and the 2020 Notes were excluded from the calculation of diluted loss per share in the three and six excluded from the diluted net loss per share in the three and six months ended

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	6 Months Ended
	Jun. 30, 2018
Investments Debt And Equity Securities [Abstract]
FINANCIAL INSTRUMENTS	(6) FINANCIAL INSTRUMENTS All marketable securities were classified as available-for-sale at June 30, 2018 and December 31, 2017. The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category as of June 30, 2018 and December 31, 2017, respectively: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 209,062 $ — $ — $ 209,062 $ 209,062 $ — $ — Level 2: Money market instruments 177,882 — — 177,882 177,882 — — Corporate debt securities 643,979 136 (3,452 ) 640,663 7,708 411,185 221,770 Commercial paper 51,818 1 — 51,819 18,947 32,871 — U.S. government agency securities 532,066 4 (1,597 ) 530,473 11,312 461,143 58,019 Foreign and other 33,035 150 (23 ) 33,162 2,500 30,463 199 Subtotal 1,438,780 291 (5,072 ) 1,433,999 218,349 935,662 279,988 Total $ 1,647,842 $ 291 $ (5,072 ) $ 1,643,061 $ 427,411 $ 935,662 $ 279,988 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 340,253 $ — $ — $ 340,253 $ 340,253 $ — $ — Level 2: Money market instruments 215,441 — — 215,441 215,441 — — Corporate debt securities 707,652 150 (2,553 ) 705,249 3,096 406,188 295,965 Commercial paper 24,566 — — 24,566 2,751 21,815 — U.S. government agency securities 472,593 — (1,975 ) 470,618 35,497 345,501 89,620 Foreign and other 25,540 150 (64 ) 25,626 990 24,436 200 Subtotal 1,445,792 300 (4,592 ) 1,441,500 257,775 797,940 385,785 Total $ 1,786,045 $ 300 $ (4,592 ) $ 1,781,753 $ 598,028 $ 797,940 $ 385,785 (1) (2) The Company’s cash equivalents and marketable securities are classified within Level 2 in the fair value hierarchy because they are valued using third-party pricing sources and remeasured on a recurring basis. 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 12 to these Condensed Consolidated Financial Statements for additional information related to the Company’s fair value measurements. 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 June 30, 2018, the Company’s investments in an unrealized loss position were not significant and were considered to be temporary in nature. 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 is deemed to have occurred.

INTANGIBLE ASSETS

INTANGIBLE ASSETS	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS	(7) INTANGIBLE ASSETS Intangible assets consisted of the following: June 30, December 31, 2018 2017 Intangible assets: Finite-lived intangible assets $ 303,298 $ 303,298 Indefinite-lived intangible assets 326,359 326,359 Gross intangible assets: 629,657 629,657 Less: Accumulated amortization (127,362 ) (112,147 ) Net carrying value $ 502,295 $ 517,510 Indefinite-Lived Intangible Assets Intangible assets related to in-process research and development (IPR&D) assets are considered to be indefinite-lived until the completion or abandonment of the associated research and development (R&D) efforts. During the second quarter of 2018, no amounts have been reclassified to definite-lived and no impairment charges were recorded. During the second quarter of 2018, the Company received $20.0 million in milestone payments due to the achievement by a third party of regulatory milestones related to a previously sold intangible asset, which th

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	6 Months Ended
	Jun. 30, 2018
Property Plant And Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	(8) PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment, net consisted of the following: June 30, December 31, 2018 2017 Building and improvements $ 674,682 $ 663,347 Manufacturing and laboratory equipment 316,331 294,521 Computer hardware and software 152,010 144,268 Leasehold improvements 38,352 42,572 Furniture and equipment 30,833 31,515 Land improvements 5,977 5,331 Land 62,369 62,369 Construction-in-progress 60,582 59,511 1,341,136 1,303,434 Accumulated depreciation (440,656 ) (406,734 ) Total property, plant and equipment, net $ 900,480 $ 896,700 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 expense for the three and six months ended June 30, 2018 was $20.1 million and $40.1 million, respectively, of which $6.6 million and $10.5 million, respectively, was capitalized into inventory. Depreciation expense for the three and six months ended June 30, 2017 was $17.9 million and $35.4 million, respectively, of which $6.2 million and $11.8 million, respectively, was capitalized into inventory. Capitalized interest related to the Company’s property, plant and equipment purchases for each of the three and six months ended June 30, 2018 and 2017 was insignificant.

SUPPLEMENTAL BALANCE SHEET INFO

SUPPLEMENTAL BALANCE SHEET INFORMATION	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
SUPPLEMENTAL BALANCE SHEET INFORMATION	(9) SUPPLEMENTAL BALANCE SHEET INFORMATION Inventory consisted of the following: June 30, December 31, 2018 2017 Raw materials $ 46,537 $ 49,877 Work-in-process 234,370 234,674 Finished goods 192,449 191,224 Total inventory $ 473,356 $ 475,775 Accounts Payable and Accrued Liabilities consisted of the following: June 30, December 31, 2018 2017 Accounts payable and accrued operating expenses $ 166,416 $ 166,616 Accrued compensation expense 94,954 140,781 Accrued rebates payable 50,944 36,472 Accrued royalties payable 18,620 18,820 Value added taxes payable 9,191 9,740 Forward foreign currency exchange contracts 7,165 14,464 Accrued income taxes 2,658 5,528 Other 8,784 9,500 Total accounts payable and accrued liabilities $ 358,732 $ 401,921

DEBT

DEBT	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
DEBT	(10) DEBT Convertible Notes As of June 30, 2018, the Company had outstanding fixed-rate notes with varying maturities for an aggregate principal amount of $1.2 billion (collectively the Notes). The Notes are senior subordinated convertible obligations, and interest is payable in arrears, quarterly. The following table summarizes information regarding the Company’s convertible debt: June 30, December 31, 2018 2017 0.75% senior subordinated convertible notes due in October 2018 $ 374,980 $ 374,980 Unamortized discount (4,659 ) (12,488 ) Unamortized deferred offering costs (569 ) (1,543 ) Convertible Notes due in 2018, net 369,752 360,949 1.50% senior subordinated convertible notes due in October 2020 374,993 374,993 Unamortized discount (33,531 ) (40,287 ) Unamortized deferred offering costs (2,983 ) (3,631 ) Convertible Notes due in 2020, net 338,479 331,075 0.599% senior subordinated convertible notes due in August 2024 495,000 495,000 Unamortized discount (8,651 ) (9,355 ) Unamortized deferred offering costs (2,957 ) (3,199 ) Convertible Notes due in 2024, net 483,392 482,446 Total convertible debt, net $ 1,191,623 $ 1,174,470 Fair value of fixed rate convertible debt Convertible Notes due in 2018 (1) $ 398,874 $ 403,955 Convertible Notes due in 2020 (1) 442,240 446,470 Convertible Notes due in 2024 (1) 502,509 493,894 Total $ 1,343,623 $ 1,344,319 (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 12 to these Condensed Consolidated Financial Statements for additional information related to the Company’s fair value measurements. Interest expense on the Company’s convertible debt consisted of the following: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Coupon interest expense $ 3,527 $ 2,194 $ 6,488 $ 4,558 Amortization of debt issuance costs 1,006 886 2,010 1,772 Accretion of discount on convertible notes 7,692 6,960 15,289 13,829 Total interest expense on convertible debt $ 12,225 $ 10,040 $ 23,787 $ 20,159 See Note 13 to the Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 for additional information related to the Company’s convertible debt. Revolving Credit Facility The Company maintains a senior unsecured revolving credit facility (Credit Facility) that provides revolving credit of up to $100.0 million in revolving loans (the Revolving Credit Facility), a $10.0 million letter of credit subfacility and a $15.0 million swingline loan subfacility. The maturity date of the Revolving Credit Facility will occur on November 29, 2018. As of June 30, 2018 and December 31, 2017, there were no outstanding amounts due on nor any usage of the Credit Facility. As of June 30, 2018, the Company and certain of its subsidiaries that serve as guarantors were in compliance with all covenants.

DERIVATIVE INSTRUMENTS AND HEDG

DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES	6 Months Ended
	Jun. 30, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES	(11) DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES 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 monetary assets and liabilities and forecasted revenues and operating expenses being denominated in currencies other than the U.S. Dollar (USD), primarily the Euro. The Company designates certain of these forward 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 USD related to changes in foreign currency exchange rates. The Company also enters into some forward foreign currency exchange contracts 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 USD. 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. The following table summarizes the Company’s designated forward foreign currency exchange contracts outstanding as of June 30, 2018 (notional amounts in millions): Aggregate Notional Number of Amount in Foreign Exchange Contracts Contracts Foreign Currency Maturity Brazilian Reais – Sell 2 143.8 Aug. 2018 Canadian Dollars – Sell 12 15.0 Jul. 2018 - Dec. 2018 Colombian Pesos – Sell 6 48,000.0 Jul. 2018 - Dec. 2018 Euros – Purchase 108 134.4 Jul. 2018 - Jun. 2021 Euros – Sell 394 488.2 Jul. 2018 - Jun. 2021 Total 522 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 June 2021. Over the next twelve months, the Company expects to reclassify unrealized losses of $2.2 million from Accumulated Other Comprehensive Loss t The following table summarizes the Company’s non-designated forward foreign currency exchange contracts outstanding as of June 30, 2018 (notional amounts in millions): Aggregate Notional Number of Amount in Foreign Exchange Contracts Contracts Foreign Currency Maturity Brazilian Reais – Purchase 5 52.2 Aug. 2018 British Pounds – Sell 1 2.6 Jul. 2018 Colombian Pesos – Sell 1 34,000.0 Jul. 2018 Euros – Purchase 3 52.2 Jul. 2018 Total 10 The fair value carrying amounts of the Company’s derivative instruments, as classified within the fair value hierarchy, were as follows: Asset Derivatives Liability Derivatives June 30, 2018 June 30, 2018 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments: Level 2 (1) Forward foreign currency exchange contracts Other current assets $ 8,599 Accounts payable and accrued liabilities $ 6,608 Forward foreign currency exchange contracts Other assets 5,852 Other long- term liabilities 4,571 Total 14,451 11,179 Derivatives not designated as hedging instruments: Level 2 (1) Forward foreign currency exchange contracts Other current assets 1,440 Accounts payable and accrued liabilities 557 Total 1,440 557 Total value of derivative contracts $ 15,891 $ 11,736 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: Level 2 (1) Forward foreign currency exchange contracts Other current assets $ 4,015 Accounts payable and 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: Level 2 (1) Forward foreign currency exchange contracts Other current assets 675 Accounts payable and accrued liabilities 44 Total 675 44 Total value of derivative contracts $ 9,663 $ 27,150 (1) See Note 12 to these Condensed Consolidated Financial Statements for additional information related to the Company’s fair value measurements. The effect of the Company’s derivative instruments on the Condensed Consolidated Financial Statements for the three and six months ended June 30, 2018 and 2017 was as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Derivatives Designated as Hedging Instruments: Net gain (loss) recognized in accumulated other comprehensive loss (1) $ 23,582 $ (19,165 ) $ 14,356 $ (23,364 ) Net gain (loss) reclassified from accumulated other comprehensive income (loss) into earnings (2) (2,659 ) 695 (8,444 ) 3,211 Net gain recognized in net loss (3) 2,700 826 2,322 1,706 Derivatives Not Designated as Hedging Instruments: Net gain (loss) recognized in net loss (4) (4,238 ) 5,373 2,985 5,631 (1) Net change in the fair value of the effective portion classified as accumulated other comprehensive loss. (2) Effective portion classified as Net Product Revenues and Operating expenses. (3) Ineffective portion and amount excluded from effectiveness testing classified as Operating expenses. (4) Classified as Operating expenses. 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	6 Months Ended
	Jun. 30, 2018
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. In addition to available-for-sale debt securities, debt and foreign currency derivatives, which are disclosed in Notes 6, 10 and 11, respectively, the following tables below present the classification within fair value hierarchy of financial assets and liabilities not disclosed elsewhere. Fair Value Measurements at June 30, 2018 Quoted Price in Active Markets For Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets: Other current assets: NQDC Plan assets $ — $ 1,018 $ — $ 1,018 Restricted investments (1) — 7,721 — 7,721 Total other current assets — 8,739 — 8,739 Other assets: NQDC Plan assets — 12,832 — 12,832 Restricted investments (1) — 6,889 — 6,889 Strategic investments (2) 1,616 — — 1,616 Total other assets 1,616 19,721 — 21,337 Total assets $ 1,616 $ 28,460 $ — $ 30,076 Liabilities: Current liabilities: NQDC Plan liability $ 1,050 $ 1,018 $ — $ 2,068 Contingent acquisition consideration — — 76,466 76,466 Total current liabilities 1,050 1,018 76,466 78,534 Other long-term liabilities: NQDC Plan liability $ 18,588 $ 12,832 — 31,420 Contingent acquisition consideration — — 57,674 57,674 Total other long-term liabilities 18,588 12,832 57,674 89,094 Total liabilities $ 19,638 $ 13,850 $ 134,140 $ 167,628 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: Other current assets: NQDC Plan assets $ — $ 967 $ — $ 967 Restricted investments (1) — 15,647 — 15,647 Total other current assets — 16,614 — 16,614 Other assets: NQDC Plan assets — 11,859 — 11,859 Total other assets — 11,859 — 11,859 Total assets $ — $ 28,473 $ — $ 28,473 Liabilities: Current liabilities: NQDC Plan liability $ 1,356 $ 967 $ — $ 2,323 Contingent acquisition consideration — — 53,648 53,648 Total current liabilities 1,356 967 53,648 55,971 Other long-term liabilities: NQDC Plan liability 18,272 11,859 — 30,131 Contingent acquisition consideration — — 135,318 135,318 Total other long-term liabilities 18,272 11,859 135,318 165,449 Total liabilities $ 19,628 $ 12,826 $ 188,966 $ 221,420 (1) The restricted investments at June 30, 2018 and December 31, 2017 secure the Company’s irrevocable standby letters of credit obtained in connection with certain commercial agreements. (2) The Company has 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 Consolidated Balance Sheets. There were no transfers between levels during the three and six months ended June 30, 2018. The Company’s Level 2 instruments 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. Liabilities measured at fair value using Level 3 inputs consisted of contingent acquisition consideration and asset retirement obligations. The following tables represent a roll-forward of contingent acquisition consideration. Contingent acquisition consideration at December 31, 2017 $ 188,966 Changes in the fair value of other contingent acquisition consideration 8,284 Milestone payments to Ares Trading S.A. (Merck Serono) (61,607 ) Foreign exchange remeasurement of Euro denominated contingent acquisition consideration (1,503 ) Contingent acquisition consideration at June 30, 2018 $ 134,140 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 June 30, 2018 and December 31, 2017, the balance of the asset retirement obligation liability was $4.2 million at each period. 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. Refer to Note 3 – Significant Accounting Policies

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
STOCK-BASED COMPENSATION	(13) STOCK-BASED COMPENSATION Compensation expense included in the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for all stock-based compensation arrangements was as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Cost of sales $ 3,246 $ 2,510 $ 6,386 $ 4,796 R&D 15,573 14,647 28,842 26,141 Selling, general and administrative 19,787 22,944 39,986 39,838 Total stock-based compensation expense $ 38,606 $ 40,101 $ 75,214 $ 70,775 Stock-based compensation expense of $5.4 million and $9.0 million was capitalized into inventory for the three and six months ended June 30, 2018, respectively, compared to stock-based compensation expense of $4.4 million and $7.6 million that was capitalized into inventory for the three and six months ended June 30, 2017, respectively. Capitalized stock-based compensation is recognized as cost of sales when the related product is sold. Equity Awards with Service-Based Vesting Conditions The assumptions used to estimate the per share fair value of stock options granted under the Company’s 2017 Equity Incentive Plan and the Company’s Amended and Restated 2006 Share Incentive Plan were as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Expected volatility 38.4% 37.8 – 39.6% 37.8 – 38.4% 37.6 – 39.7% Dividend yield 0.0% 0.0% 0.0% 0.0% Expected life 5.7 years 5.0 – 6.6 years 4.6 – 5.7 years 5.0 – 6.6 years Risk-free interest rate 2.7% 1.8 – 1.9% 2.3 – 2.7% 1.8 – 2.2% During the six The Company issued new stock purchase rights under the ESPP during the three and six months ended June 30, 2018, using the following assumptions to estimate the per share fair value: Three and Six Months Ended June 30, 2018 2017 Expected volatility 29.7 - 33.3% 30.7 - 42.3% Dividend yield 0.0% 0.0% Expected life 6-24 months 6-24 months Risk-free interest rate 1.2 - 2.5% 1.0 - 1.3% During the six 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 2018, the Compensation Committee and Board approved the grant of 129,680 RSUs (base RSUs) with performance-based vesting conditions. This award is contingent upon the achievement of a 2018 revenue target and the awarded RSUs, if any, vest ratably over a three-year service period. The number of shares that may be earned range between of the base RSUs, dependent on the percentage of 2018 “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 RSUs with performance-based vesting conditions with similar performance conditions were granted in 2017, 2016 and 2015. The following table details the base RSUs granted, RSUs earned and expected to vest and the performance multiplier achieved for the RSUs with performance-based vesting conditions for the years ended December 31, 2017, 2016 and 2015, respectively, as well as the base RSUs granted in March 2018: Grant Date Date of Grant Base RSUs Granted Fair Value per RSU Multiplier Achieved RSUs Earned March 2018 129,680 $ 83.57 (a) (a) March 2017 133,250 $ 87.42 1.03 132,548 March 2016 130,310 $ 83.43 1.03 134,219 March 2015 58,300 $ 108.36 1.11 64,713 (a) The Company’s Compensation Committee is expected to approve the multiplier and total earned RSUs in the first quarter of 2019 based on the Company’s performance against the 2018 managed revenue target. The Company evaluated the 2018 revenue target in the context of its current 2018 revenue forecast, and related confidence level in the forecast, and determined that attainment of the revenue target was probable for accounting purposes commencing in the first quarter of 2018.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	(14) ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following table summarizes amounts reclassified out of AOCI and their effect on the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for the three and six months ended June 30, 2018 and 2017. Condensed Consolidated Three Months Ended June 30, Six Months Ended June 30, Statement of Details about AOCI Components 2018 2017 2018 2017 Comprehensive Loss Classification Gains (losses) on cash flow hedges: Forward foreign currency exchange contracts $ (4,062 ) $ 1,119 $ (11,708 ) $ 4,661 Net product revenues Forward foreign currency exchange contracts 1,403 (424 ) 3,264 (1,450 ) Operating expenses Total gain (loss) on cash flow hedges (2,659 ) 695 (8,444 ) 3,211 Gain on sale of available-for-sale debt securities — — — 3,252 Other income Income tax effect of the above — — — (1,181 ) Benefit from income taxes Total gain on available-for-sale debt securities — — — 2,071 $ (2,659 ) $ 695 $ (8,444 ) $ 5,282 Net loss The following tables summarize changes in the accumulated balances for each component of AOCI, including current period other comprehensive income (loss) and reclassifications out of AOCI for the three and six months ended June 30, 2018 and 2017. Three Months Ended June 30, 2018 Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Available-for-Sale Debt Securities Foreign Currency Items Total AOCI balance at March 31, 2018 $ (23,673 ) $ (4,866 ) $ (6 ) $ (28,545 ) Other comprehensive income (loss) before reclassifications 23,582 1,531 (5 ) 25,108 Less: net loss reclassified from AOCI (2,659 ) — — (2,659 ) Tax effect — (351 ) — (351 ) Net current-period other comprehensive income (loss) 26,241 1,180 (5 ) 27,416 AOCI balance at June 30, 2018 $ 2,568 $ (3,686 ) $ (11 ) $ (1,129 ) Three Months Ended June 30, 2017 Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Available-for-Sale Debt Securities Foreign Currency Items Total AOCI balance at March 31, 2017 $ 6,291 $ (1,258 ) $ (13 ) $ 5,020 Other comprehensive income (loss) before reclassifications (19,165 ) 267 4 (18,894 ) Less: gain reclassified from AOCI 695 — — 695 Tax effect — (89 ) — (89 ) Net current-period other comprehensive income (loss) (19,860 ) 178 4 (19,678 ) AOCI balance at June 30, 2017 $ (13,569 ) $ (1,080 ) $ (9 ) $ (14,658 ) Six Months Ended June 30, 2018 Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Available-for-Sale Securities Foreign Currency Items Total AOCI balance at December 31, 2017 $ (20,232 ) $ (2,722 ) $ (7 ) $ (22,961 ) Impact of change in accounting principle (1) — $ (586 ) — $ (586 ) AOCI balance at January 1, 2018 $ (20,232 ) $ (3,308 ) $ (7 ) $ (23,547 ) Other comprehensive income (loss) before reclassifications 14,356 (490 ) (4 ) 13,862 Less: loss reclassified from AOCI (8,444 ) — — (8,444 ) Tax effect — 112 — 112 Net current-period other comprehensive income (loss) 22,800 (378 ) (4 ) 22,418 AOCI balance at June 30, 2018 $ 2,568 $ (3,686 ) $ (11 ) $ (1,129 ) (1) As of January 1, 2018, the Company early adopted the requirements of ASU 2018-02. The amount represents the reclassification from Accumulated Other Comprehensive Income (Loss) to Accumulated Deficit in the first quarter of 2018 related to the adoption of ASU 2018-02. See Note 4 for additional discussion . Six Months Ended June 30, 2017 Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Available-for-Sale Securities Foreign Currency Items Total AOCI balance at December 31, 2016 $ 13,006 $ (178 ) $ (12 ) $ 12,816 Other comprehensive income (loss) before reclassifications (23,364 ) 1,834 3 (21,527 ) Less: gain reclassified from AOCI 3,211 3,252 — 6,463 Tax effect — 516 — 516 Net current-period other comprehensive income (loss) (26,575 ) (902 ) 3 (27,474 ) AOCI balance at June 30, 2017 $ (13,569 ) $ (1,080 ) $ (9 ) $ (14,658 )

REVENUE, CREDIT CONCENTRATIONS

REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION	6 Months Ended
	Jun. 30, 2018
Concentration Risk And Geographic Information [Abstract]
REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION	(15) REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION The Company operates in one business segment, which primarily focuses on the development and commercialization of innovative therapies for people with serious and life threatening rare diseases and medical conditions. The Company considers there to be revenue concentration risks for regions where net product revenues exceed 10% of consolidated net product revenues. The concentration of the Company’s net product revenues within the regions below may have a material adverse effect on the Company’s revenues and results of operations if sales in the respective regions experience difficulties. The Company adopted the requirements of ASC 606 on January 1, 2018 using the modified retrospective method, therefore there is a lack of comparability to the prior periods presented. See Note 4 – Recent Accounting Pronouncements The following table disaggregates Total Revenues from external customers and collaborative partners by geographic region. Net product revenues by geographic region are based on patient location for the Company’s commercial products, except for Aldurazyme. 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 is located in the U.S. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total revenues by geographic region: United States $ 162,788 $ 141,611 $ 353,360 $ 274,095 Europe 107,221 87,672 212,871 171,577 Latin America 58,158 66,739 96,633 112,035 Rest of world 44,678 21,426 83,428 63,486 Total revenues $ 372,845 $ 317,448 $ 746,292 $ 621,193 The following table disaggregates total Net Product Revenues from external customers by product. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net product revenues by product: Aldurazyme $ 24,003 $ 19,985 $ 90,059 $ 39,340 Brineura 10,890 254 17,807 254 Firdapse 5,177 4,855 10,103 8,965 Kuvan 109,045 101,944 208,160 194,290 Naglazyme 91,086 85,751 166,082 166,309 Vimizim 127,585 103,137 244,674 208,958 Total net product revenues $ 367,786 $ 315,926 $ 736,885 $ 618,116 The table below disaggregates total Net Product Revenues 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 ’ Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 United States $ 138,411 $ 121,256 $ 262,552 $ 233,962 Europe 104,262 87,672 207,419 171,577 Latin America 58,158 66,738 96,633 112,032 Rest of world 42,952 20,275 80,222 61,205 Total net product revenue marketed by the Company 343,783 295,941 646,826 578,776 Aldurazyme net product revenues marketed by Genzyme 24,003 19,985 90,059 39,340 Total net product revenues $ 367,786 $ 315,926 $ 736,885 $ 618,116 The following table illustrates the percentage of the Company’s total Net Product Revenues attributed to the Company’s largest customers for the three and six months ended June 30, 2018 and 2017. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Customer A 18 % 17 % 18 % 17 % Customer B 7 % 6 % 12 % 6 % Customer C 12 % 14 % 12 % 13 % Customer D 10 % 10 % 9 % 10 % Customer E 4 % 10 % 2 % 7 % Total 51 % 57 % 53 % 53 % On a consolidated basis, the Company’s two largest customer accounts receivable balances accounted for 30% and 15% of the June 30, 2018 total accounts receivable balance, respectively, compared to December 31, 2017, when the two largest customer accounts receivable balances accounted for 21% and 18% of the total accounts receivable balance, respectively. As of June 30, 2018, and December 31, 2017, the accounts receivable balance for Genzyme included $85.0 million and $18.1 million, respectively, of unbilled accounts receivable, which become payable to the Company when the product is sold through by Genzyme. The Company does not require collateral from its customers, but does perform periodic credit evaluations of its customers’ financial condition and requires 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.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	(16) COMMITMENTS AND CONTINGENCIES Contingencies From time to time the Company is involved in legal actions arising in the normal course of its business. The process of resolving matters through litigation or other means is inherently uncertain and it is possible that an unfavorable resolution of these matters could adversely affect the Company, its results of operations, financial condition 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. Contingent Payments As of June 30, 2018, the Company is subject to contingent payments totaling approximately $540.4 million upon achievement of certain development and regulatory activities and commercial sales and licensing milestones if they occur before certain dates in the future. Of this amount, $158.0 million relates to the acquisition of certain rights and other assets with respect to Kuvan and Palynziq from Merck Serono and $53.2 million relates to programs that are no longer being developed. As of June 30, 2018, the Company has recorded a total of $134.1 million of contingent acquisition consideration on its Condensed Consolidated Balances Sheet. The Company paid $61.6 million of contingent acquisition consideration in April 2018 related to the filing of the European Marketing Authorization Application for Palynziq. See Note 12 to these Condensed Consolidated Financial Statements for further information regarding the Company’s contingent acquisition consideration. Other Commitments In the normal course of business, the Company enters into various firm purchase commitments primarily related to active pharmaceutical ingredients June 30, 2018

BENEFIT FROM INCOME TAXES

BENEFIT FROM INCOME TAXES	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
BENEFIT FROM INCOME TAXES	(17) BENEFIT FROM INCOME TAXES The 2017 Tax Act, which became effective on January 1, 2018 resulted in significant changes to the U.S. corporate income tax system including a federal statutory rate reduction from 35% to 21% and the elimination or reduction of certain domestic deductions and credits. The 2017 Tax Act changed U.S. international taxation from a worldwide basis to a modified territorial system that includes base erosion prevention measures on foreign earnings. This will result in the Company’s foreign subsidiaries being subject to U.S. taxation in the future. U.S. and foreign tax expense was computed using a forecasted annual effective tax rate for the three and six months ended June 30, 2018 from income taxes for the three and six months ended June 30, 2017 using an actual year-to-date tax calculation. Foreign tax expense was computed using a forecasted annual effective tax rate for the three and six months ended June 30, 2017. The Company included a provisional estimate of the impact of the 2017 Tax Act in its 2017 tax provision in accordance with its interpretation of the 2017 Tax

SIGNIFICANT ACCOUNTING POLICI24

SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	The accompanying Condensed Consolidated Financial Statements have been prepared pursuant to U.S. generally accepted accounting principles (U.S. GAAP) and the rules and regulations of the SEC for Quarterly Reports on Form 10-Q and do not include all of the information and note disclosures required by U.S. GAAP for complete financial statements, although the Company believes that the disclosures herein are adequate to ensure that the information presented is not misleading. The Condensed Consolidated Financial Statements should therefore be read in conjunction with the Consolidated Financial Statements and Notes thereto for the fiscal year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K. Effective January 1, 2018, the Company adopted the requirements of Accounting Standards Codification 606, Revenue from Contracts with Customers Significant Accounting Policies U.S. GAAP requires management to make estimates and assumptions that affect amounts reported in the Condensed Consolidated Financial Statements and accompanying disclosures. Although these estimates are based on management’s best knowledge of current events and actions that the Company may undertake in the future, actual results may be different from those estimates. The Condensed Consolidated Financial Statements reflect all adjustments of a normal, recurring nature that are, in the opinion of management, necessary for a fair presentation of results for these interim periods. The results of operations for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2018 or any other period. Management performed an evaluation of the Company’s activities through the date of filing of this Quarterly Report on Form 10-Q, and has concluded that there were no subsequent events or transactions that occurred subsequent to the balance sheet date prior to filing this Quarterly Report on Form 10-Q that would require recognition or disclosure in the Condensed Consolidated Financial Statements.
Net Product Revenues	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. 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. Revenues from product sales are recognized when the customer obtains control of the Company’s product, which occurs at a point in time, typically upon shipment to the customer. Amounts collected from customers and remitted to governmental authorities, which primarily consist of value-added taxes related to product sales in foreign jurisdictions, are presented on a net basis in the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss), in that taxes billed to customers are not included as a component of Net Product Revenues. For Aldurazyme revenues, the Company receives a payment ranging from 39.5% to 50% on worldwide net Aldurazyme sales by Genzyme Corporation (Genzyme) depending on sales volume, which is included in Net Product Revenues in the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss). Under the previous guidance the Company only recognized a portion of this amount as product transfer revenue when the product was released to Genzyme because all of the Company’s performance obligations were fulfilled at that point, the prices were substantially fixed or determinable and title to, and risk of loss for, the product had transferred to Genzyme. The product transfer revenue only represented the fixed amount per unit of Aldurazyme that Genzyme was required to pay the Company if the product was unsold by Genzyme. The amount of product transfer revenue was eventually deducted from the calculated royalty recognized when the product was subsequently sold by Genzyme. The Company recorded the Aldurazyme revenues based on net sales information provided by Genzyme and recorded product transfer revenues based on the fulfillment of Genzyme purchase orders in accordance with the terms of the related agreements with Genzyme. Under ASC 606, the Company recognizes its best estimate of the entire revenue that it expects to receive when the product is released and control is transferred to Genzyme. The Company records Aldurazyme net product revenues based on the estimated variable consideration payable when the product is sold through by Genzyme. Actual amounts of consideration ultimately received may differ from the Company’s estimates, however the Company does not expect any such difference to be material. If actual results in the future vary from the Company’s estimates, the Company will make adjustments, which would affect Net Product Revenues and earnings in the period such variances become known.
Revenue Reserves	Revenue Reserves Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration for which reserves are established and which result from government rebates, sales returns, and other incentives that are offered within contracts between the Company and its customers, as such specialty pharmacies, hospitals, authorized distributors and government purchasers. These reserves are based on the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable (if the amount is payable to the customer) or a current liability (if the amount is payable to a party other than a customer). Where appropriate, these estimates take into consideration a range of possible outcomes which are probability-weighted for relevant factors such as the Company’s historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained, and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust its estimates, which would affect net product revenue and earnings in the period such variances become known. Government Rebates : The Company records reserves for rebates payable under Medicaid and other government programs as a reduction of revenue at the time product revenues are recorded. The Company’s reserve calculations require estimates, including estimates of customer mix, to determine which sales will be subject to rebates and the amount of such rebates. The Company updates its estimates and assumptions on a quarterly basis and records any necessary adjustments to its reserves. Sales Returns : The Company records allowances for product returns, if appropriate, as a reduction of revenue at the time product sales are recorded. 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 historical 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. The Company relies on historical return rates to estimate returns. 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. Other Incentives : Other incentives include fees paid to the Company’s distributors, discounts for prompt payment and the estimated costs of the Company’s patient co-payment assistance programs. Beginning in 2018, the Company also offers a branded co-pay assistance program for eligible patients with commercial insurance in the U.S. who are on Kuvan or Brineura therapy. The branded co-pay assistance programs assist commercially insured patients who have coverage for Kuvan or Brineura and are intended to reduce each participating patient’s portion of the financial responsibility for Kuvan’s or Brineura’s purchase price up to a specified dollar amount of assistance. The Company records fees paid to distributors, cash discounts and amounts paid under the branded specific co-pay assistance program for each patient as a reduction of revenue.
Royalty and Other Revenues	Royalty and Other Revenues Royalties : For arrangements that include the receipt of sales-based royalties, including milestone payments based on the level of sales when the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (a) when the related sales occur, or (b) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone payments : At the inception of each arrangement that includes developmental, regulatory or commercial milestone payments, the Company evaluates whether achieving the milestones is considered probable and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated milestone (such as a regulatory submission by the Company) is included in the transaction price. Milestone payments that are not within the control of the Company, such as approvals from regulators or where attainment of the specified event is dependent on the development activities of a third-party, are not considered probable of being achieved until those approvals are received or the specified event occurs. Revenue is recognized from the satisfaction of performance obligations in the amount billable to the customer .

RECENT ACCOUNTING PRONOUNCEME25

RECENT ACCOUNTING PRONOUNCEMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
Summary of Adjustments to Accounts on Condensed Consolidated Balance Sheet, Comprehensive Income (Loss) Statements and Cash Flows Statement	The cumulative effect of applying the new guidance of ASC 606 As Reported Adjusted December 31, 2017 Aldurazyme (1) Tax Provision (2) January 1, 2018 Balance Sheet Assets: Accounts receivable, net $ 261,365 $ 26,012 $ — $ 287,377 Deferred tax assets $ 399,095 $ — $ (5,964 ) $ 393,131 Total assets $ 4,633,125 $ 26,012 $ (5,964 ) $ 4,653,173 Equity: Accumulated deficit $ (1,637,548 ) $ 26,012 $ (5,964 ) $ (1,617,500 ) Total liabilities and stockholders' equity $ 4,633,125 $ 26,012 $ (5,964 ) $ 4,653,173 (1) This adjustment represents management’s estimate of the variable consideration to be earned on worldwide sales of Aldurazyme by Genzyme in excess of the product transfer revenue previously recognized for Genzyme’s ending inventory at December 31, 2017. The product transfer revenue previously recognized as revenue represents the fixed amount per unit of Aldurazyme that Genzyme was required to pay the Company if the product was unsold by Genzyme. (2) The adoption of ASC 606 primarily resulted in an acceleration of the variable consideration components of revenue as of December 31, 2017, which in turn generated additional deferred tax liabilities that ultimately reduced the Company's net deferred tax asset position. The tax provision amount has been calculated using the Company’s estimated statutory rate. The impact of adoption on the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for the three and six months ended June 30, 2018 was as follows: Three Months Ended June 30, 2018 Balance without Adoption of As Reported Adjustments (1) ASC 606 Net product revenues $ 367,786 $ 48 $ 367,834 Benefit from income taxes $ (12,385 ) $ 11 $ (12,374 ) Net loss $ (16,792 ) $ 37 $ (16,755 ) Six Months Ended June 30, 2018 Balance without Adoption of As Reported Adjustments (1) ASC 606 Net product revenues $ 736,885 $ (27,150 ) $ 709,735 Benefit from income taxes $ (19,040 ) $ (6,225 ) $ (25,265 ) Net loss $ (60,941 ) $ (20,925 ) $ (81,866 ) (1) The adoption of ASC 606 resulted in additional revenues recognized in the first half of 2018, which in turn generated additional deferred tax liabilities that reduced the Company's benefit from income taxes. The Benefit from Income Taxes amount has been calculated using the Company’s estimated statutory rate. The impact of adoption on the Company’s Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2018 was as follows: Balance without Adoption of As Reported Adjustments (1) ASC 606 Net loss $ (60,941 ) $ (20,925 ) $ (81,866 ) Deferred income taxes $ (29,681 ) $ (6,225 ) $ (35,906 ) Changes in operating assets and liabilities: Accounts receivable, net $ (77,416 ) $ 27,150 $ (50,266 ) Net cash used in operating activities $ (76,366 ) $ — $ (76,366 ) (1) The adoption of ASC 606 resulted in decreased Net Loss and increased Accounts Receivable, Net due to additional revenues recognized in the first quarter of 2018, which in turn generated additional deferred tax liabilities that reduced the Company's net Deferred Tax Assets. The Deferred Income Taxes amount has been calculated using the Company’s estimated statutory rate.

NET LOSS PER COMMON SHARE (Tabl

NET LOSS PER COMMON SHARE (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
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 of common shares): Three and Six Months Ended June 30, 2018 2017 Options to purchase common stock 7,829 8,440 Common stock issuable under the 2018 Notes 3,983 3,983 Common stock issuable under the 2020 Notes 3,983 3,983 Common stock issuable under the 2024 Notes 3,970 — Unvested restricted stock units 3,544 3,041 Common stock potentially issuable for ESPP purchases 433 387 Common stock held by the NQDC 208 224 Total number of potentially issuable shares 23,950 20,058

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
Investments Debt And Equity Securities [Abstract]
Schedule of Cash, Cash Equivalents and Available-for-Sale Securities by Significant Investment Category	The following tables show the Company’s cash, cash equivalents and available-for-sale securities by significant investment category as of June 30, 2018 and December 31, 2017, respectively: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 209,062 $ — $ — $ 209,062 $ 209,062 $ — $ — Level 2: Money market instruments 177,882 — — 177,882 177,882 — — Corporate debt securities 643,979 136 (3,452 ) 640,663 7,708 411,185 221,770 Commercial paper 51,818 1 — 51,819 18,947 32,871 — U.S. government agency securities 532,066 4 (1,597 ) 530,473 11,312 461,143 58,019 Foreign and other 33,035 150 (23 ) 33,162 2,500 30,463 199 Subtotal 1,438,780 291 (5,072 ) 1,433,999 218,349 935,662 279,988 Total $ 1,647,842 $ 291 $ (5,072 ) $ 1,643,061 $ 427,411 $ 935,662 $ 279,988 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash and Cash Equivalents Short-term Marketable Securities (1) Long-term Marketable Securities (2) Level 1: Cash $ 340,253 $ — $ — $ 340,253 $ 340,253 $ — $ — Level 2: Money market instruments 215,441 — — 215,441 215,441 — — Corporate debt securities 707,652 150 (2,553 ) 705,249 3,096 406,188 295,965 Commercial paper 24,566 — — 24,566 2,751 21,815 — U.S. government agency securities 472,593 — (1,975 ) 470,618 35,497 345,501 89,620 Foreign and other 25,540 150 (64 ) 25,626 990 24,436 200 Subtotal 1,445,792 300 (4,592 ) 1,441,500 257,775 797,940 385,785 Total $ 1,786,045 $ 300 $ (4,592 ) $ 1,781,753 $ 598,028 $ 797,940 $ 385,785 (1) (2)

INTANGIBLE ASSETS (Tables)

INTANGIBLE ASSETS (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	Intangible assets consisted of the following: June 30, December 31, 2018 2017 Intangible assets: Finite-lived intangible assets $ 303,298 $ 303,298 Indefinite-lived intangible assets 326,359 326,359 Gross intangible assets: 629,657 629,657 Less: Accumulated amortization (127,362 ) (112,147 ) Net carrying value $ 502,295 $ 517,510

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	6 Months Ended
	Jun. 30, 2018
Property Plant And Equipment [Abstract]
Schedule of Property Plant and Equipment Net	Property, plant and equipment, net consisted of the following: June 30, December 31, 2018 2017 Building and improvements $ 674,682 $ 663,347 Manufacturing and laboratory equipment 316,331 294,521 Computer hardware and software 152,010 144,268 Leasehold improvements 38,352 42,572 Furniture and equipment 30,833 31,515 Land improvements 5,977 5,331 Land 62,369 62,369 Construction-in-progress 60,582 59,511 1,341,136 1,303,434 Accumulated depreciation (440,656 ) (406,734 ) Total property, plant and equipment, net $ 900,480 $ 896,700

SUPPLEMENTAL BALANCE SHEET IN30

SUPPLEMENTAL BALANCE SHEET INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Inventory	Inventory consisted of the following: June 30, December 31, 2018 2017 Raw materials $ 46,537 $ 49,877 Work-in-process 234,370 234,674 Finished goods 192,449 191,224 Total inventory $ 473,356 $ 475,775
Schedule of Accounts Payable and Accrued Liabilities	Accounts Payable and Accrued Liabilities consisted of the following: June 30, December 31, 2018 2017 Accounts payable and accrued operating expenses $ 166,416 $ 166,616 Accrued compensation expense 94,954 140,781 Accrued rebates payable 50,944 36,472 Accrued royalties payable 18,620 18,820 Value added taxes payable 9,191 9,740 Forward foreign currency exchange contracts 7,165 14,464 Accrued income taxes 2,658 5,528 Other 8,784 9,500 Total accounts payable and accrued liabilities $ 358,732 $ 401,921

DEBT (Tables)

DEBT (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Summary of Convertible Debt	The following table summarizes information regarding the Company’s convertible debt: June 30, December 31, 2018 2017 0.75% senior subordinated convertible notes due in October 2018 $ 374,980 $ 374,980 Unamortized discount (4,659 ) (12,488 ) Unamortized deferred offering costs (569 ) (1,543 ) Convertible Notes due in 2018, net 369,752 360,949 1.50% senior subordinated convertible notes due in October 2020 374,993 374,993 Unamortized discount (33,531 ) (40,287 ) Unamortized deferred offering costs (2,983 ) (3,631 ) Convertible Notes due in 2020, net 338,479 331,075 0.599% senior subordinated convertible notes due in August 2024 495,000 495,000 Unamortized discount (8,651 ) (9,355 ) Unamortized deferred offering costs (2,957 ) (3,199 ) Convertible Notes due in 2024, net 483,392 482,446 Total convertible debt, net $ 1,191,623 $ 1,174,470 Fair value of fixed rate convertible debt Convertible Notes due in 2018 (1) $ 398,874 $ 403,955 Convertible Notes due in 2020 (1) 442,240 446,470 Convertible Notes due in 2024 (1) 502,509 493,894 Total $ 1,343,623 $ 1,344,319 (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 12 to these Condensed Consolidated Financial Statements for additional information related to the Company’s fair value measurements.
Summary of Interest Expense on Debt	Interest expense on the Company’s convertible debt consisted of the following: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Coupon interest expense $ 3,527 $ 2,194 $ 6,488 $ 4,558 Amortization of debt issuance costs 1,006 886 2,010 1,772 Accretion of discount on convertible notes 7,692 6,960 15,289 13,829 Total interest expense on convertible debt $ 12,225 $ 10,040 $ 23,787 $ 20,159

DERIVATIVE INSTRUMENTS AND HE32

DERIVATIVE INSTRUMENTS AND HEDGING STRATEGIES (Tables)	6 Months Ended
	Jun. 30, 2018
Derivative [Line Items]
Fair Value Carrying Amount of Derivative Instruments	The fair value carrying amounts of the Company’s derivative instruments, as classified within the fair value hierarchy, were as follows: Asset Derivatives Liability Derivatives June 30, 2018 June 30, 2018 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments: Level 2 (1) Forward foreign currency exchange contracts Other current assets $ 8,599 Accounts payable and accrued liabilities $ 6,608 Forward foreign currency exchange contracts Other assets 5,852 Other long- term liabilities 4,571 Total 14,451 11,179 Derivatives not designated as hedging instruments: Level 2 (1) Forward foreign currency exchange contracts Other current assets 1,440 Accounts payable and accrued liabilities 557 Total 1,440 557 Total value of derivative contracts $ 15,891 $ 11,736 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: Level 2 (1) Forward foreign currency exchange contracts Other current assets $ 4,015 Accounts payable and 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: Level 2 (1) Forward foreign currency exchange contracts Other current assets 675 Accounts payable and accrued liabilities 44 Total 675 44 Total value of derivative contracts $ 9,663 $ 27,150 (1) See Note 12 to these Condensed Consolidated Financial Statements for additional information related to the Company’s fair value measurements.
Effect of Derivative Instruments	The effect of the Company’s derivative instruments on the Condensed Consolidated Financial Statements for the three and six months ended June 30, 2018 and 2017 was as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Derivatives Designated as Hedging Instruments: Net gain (loss) recognized in accumulated other comprehensive loss (1) $ 23,582 $ (19,165 ) $ 14,356 $ (23,364 ) Net gain (loss) reclassified from accumulated other comprehensive income (loss) into earnings (2) (2,659 ) 695 (8,444 ) 3,211 Net gain recognized in net loss (3) 2,700 826 2,322 1,706 Derivatives Not Designated as Hedging Instruments: Net gain (loss) recognized in net loss (4) (4,238 ) 5,373 2,985 5,631 (1) Net change in the fair value of the effective portion classified as accumulated other comprehensive loss. (2) Effective portion classified as Net Product Revenues and Operating expenses. (3) Ineffective portion and amount excluded from effectiveness testing classified as Operating expenses. (4) Classified as Operating expenses.
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Summary of Designated Forward Foreign Currency Exchange Contracts Outstanding	The following table summarizes the Company’s designated forward foreign currency exchange contracts outstanding as of June 30, 2018 (notional amounts in millions): Aggregate Notional Number of Amount in Foreign Exchange Contracts Contracts Foreign Currency Maturity Brazilian Reais – Sell 2 143.8 Aug. 2018 Canadian Dollars – Sell 12 15.0 Jul. 2018 - Dec. 2018 Colombian Pesos – Sell 6 48,000.0 Jul. 2018 - Dec. 2018 Euros – Purchase 108 134.4 Jul. 2018 - Jun. 2021 Euros – Sell 394 488.2 Jul. 2018 - Jun. 2021 Total 522
Not Designated as Hedging Instrument
Derivative [Line Items]
Summary of Designated Forward Foreign Currency Exchange Contracts Outstanding	The following table summarizes the Company’s non-designated forward foreign currency exchange contracts outstanding as of June 30, 2018 (notional amounts in millions): Aggregate Notional Number of Amount in Foreign Exchange Contracts Contracts Foreign Currency Maturity Brazilian Reais – Purchase 5 52.2 Aug. 2018 British Pounds – Sell 1 2.6 Jul. 2018 Colombian Pesos – Sell 1 34,000.0 Jul. 2018 Euros – Purchase 3 52.2 Jul. 2018 Total 10

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities	The Company measures certain financial assets and liabilities at fair value on a recurring basis. In addition to available-for-sale debt securities, debt and foreign currency derivatives, which are disclosed in Notes 6, 10 and 11, respectively, the following tables below present the classification within fair value hierarchy of financial assets and liabilities not disclosed elsewhere. Fair Value Measurements at June 30, 2018 Quoted Price in Active Markets For Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets: Other current assets: NQDC Plan assets $ — $ 1,018 $ — $ 1,018 Restricted investments (1) — 7,721 — 7,721 Total other current assets — 8,739 — 8,739 Other assets: NQDC Plan assets — 12,832 — 12,832 Restricted investments (1) — 6,889 — 6,889 Strategic investments (2) 1,616 — — 1,616 Total other assets 1,616 19,721 — 21,337 Total assets $ 1,616 $ 28,460 $ — $ 30,076 Liabilities: Current liabilities: NQDC Plan liability $ 1,050 $ 1,018 $ — $ 2,068 Contingent acquisition consideration — — 76,466 76,466 Total current liabilities 1,050 1,018 76,466 78,534 Other long-term liabilities: NQDC Plan liability $ 18,588 $ 12,832 — 31,420 Contingent acquisition consideration — — 57,674 57,674 Total other long-term liabilities 18,588 12,832 57,674 89,094 Total liabilities $ 19,638 $ 13,850 $ 134,140 $ 167,628 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: Other current assets: NQDC Plan assets $ — $ 967 $ — $ 967 Restricted investments (1) — 15,647 — 15,647 Total other current assets — 16,614 — 16,614 Other assets: NQDC Plan assets — 11,859 — 11,859 Total other assets — 11,859 — 11,859 Total assets $ — $ 28,473 $ — $ 28,473 Liabilities: Current liabilities: NQDC Plan liability $ 1,356 $ 967 $ — $ 2,323 Contingent acquisition consideration — — 53,648 53,648 Total current liabilities 1,356 967 53,648 55,971 Other long-term liabilities: NQDC Plan liability 18,272 11,859 — 30,131 Contingent acquisition consideration — — 135,318 135,318 Total other long-term liabilities 18,272 11,859 135,318 165,449 Total liabilities $ 19,628 $ 12,826 $ 188,966 $ 221,420 (1) The restricted investments at June 30, 2018 and December 31, 2017 secure the Company’s irrevocable standby letters of credit obtained in connection with certain commercial agreements. (2) The Company has 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 Consolidated Balance Sheets.
Liabilities Measured at Fair Value Using Level 3 Inputs	Contingent acquisition consideration at December 31, 2017 $ 188,966 Changes in the fair value of other contingent acquisition consideration 8,284 Milestone payments to Ares Trading S.A. (Merck Serono) (61,607 ) Foreign exchange remeasurement of Euro denominated contingent acquisition consideration (1,503 ) Contingent acquisition consideration at June 30, 2018 $ 134,140

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation Expense	Compensation expense included in the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for all stock-based compensation arrangements was as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Cost of sales $ 3,246 $ 2,510 $ 6,386 $ 4,796 R&D 15,573 14,647 28,842 26,141 Selling, general and administrative 19,787 22,944 39,986 39,838 Total stock-based compensation expense $ 38,606 $ 40,101 $ 75,214 $ 70,775
Stock Option Valuation Assumptions	The assumptions used to estimate the per share fair value of stock options granted under the Company’s 2017 Equity Incentive Plan and the Company’s Amended and Restated 2006 Share Incentive Plan were as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Expected volatility 38.4% 37.8 – 39.6% 37.8 – 38.4% 37.6 – 39.7% Dividend yield 0.0% 0.0% 0.0% 0.0% Expected life 5.7 years 5.0 – 6.6 years 4.6 – 5.7 years 5.0 – 6.6 years Risk-free interest rate 2.7% 1.8 – 1.9% 2.3 – 2.7% 1.8 – 2.2%
Stock Purchase Rights Assumptions	The Company issued new stock purchase rights under the ESPP during the three and six months ended June 30, 2018, using the following assumptions to estimate the per share fair value: Three and Six Months Ended June 30, 2018 2017 Expected volatility 29.7 - 33.3% 30.7 - 42.3% Dividend yield 0.0% 0.0% Expected life 6-24 months 6-24 months Risk-free interest rate 1.2 - 2.5% 1.0 - 1.3%
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 for the RSUs with performance-based vesting conditions for the years ended December 31, 2017, 2016 and 2015, respectively, as well as the base RSUs granted in March 2018: Grant Date Date of Grant Base RSUs Granted Fair Value per RSU Multiplier Achieved RSUs Earned March 2018 129,680 $ 83.57 (a) (a) March 2017 133,250 $ 87.42 1.03 132,548 March 2016 130,310 $ 83.43 1.03 134,219 March 2015 58,300 $ 108.36 1.11 64,713 (a) The Company’s Compensation Committee is expected to approve the multiplier and total earned RSUs in the first quarter of 2019 based on the Company’s performance against the 2018 managed revenue target. The Company evaluated the 2018 revenue target in the context of its current 2018 revenue forecast, and related confidence level in the forecast, and determined that attainment of the revenue target was probable for accounting purposes commencing in the first quarter of 2018.

ACCUMULATED OTHER COMPREHENSI35

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Amounts Reclassified out of AOCI	The following table summarizes amounts reclassified out of AOCI and their effect on the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for the three and six months ended June 30, 2018 and 2017. Condensed Consolidated Three Months Ended June 30, Six Months Ended June 30, Statement of Details about AOCI Components 2018 2017 2018 2017 Comprehensive Loss Classification Gains (losses) on cash flow hedges: Forward foreign currency exchange contracts $ (4,062 ) $ 1,119 $ (11,708 ) $ 4,661 Net product revenues Forward foreign currency exchange contracts 1,403 (424 ) 3,264 (1,450 ) Operating expenses Total gain (loss) on cash flow hedges (2,659 ) 695 (8,444 ) 3,211 Gain on sale of available-for-sale debt securities — — — 3,252 Other income Income tax effect of the above — — — (1,181 ) Benefit from income taxes Total gain on available-for-sale debt securities — — — 2,071 $ (2,659 ) $ 695 $ (8,444 ) $ 5,282 Net loss
Summary of Changes in Accumulated Balances of AOCI Including Current Period Other Comprehensive Income (Loss) and Reclassifications Out of AOCI	The following tables summarize changes in the accumulated balances for each component of AOCI, including current period other comprehensive income (loss) and reclassifications out of AOCI for the three and six months ended June 30, 2018 and 2017. Three Months Ended June 30, 2018 Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Available-for-Sale Debt Securities Foreign Currency Items Total AOCI balance at March 31, 2018 $ (23,673 ) $ (4,866 ) $ (6 ) $ (28,545 ) Other comprehensive income (loss) before reclassifications 23,582 1,531 (5 ) 25,108 Less: net loss reclassified from AOCI (2,659 ) — — (2,659 ) Tax effect — (351 ) — (351 ) Net current-period other comprehensive income (loss) 26,241 1,180 (5 ) 27,416 AOCI balance at June 30, 2018 $ 2,568 $ (3,686 ) $ (11 ) $ (1,129 ) Three Months Ended June 30, 2017 Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Available-for-Sale Debt Securities Foreign Currency Items Total AOCI balance at March 31, 2017 $ 6,291 $ (1,258 ) $ (13 ) $ 5,020 Other comprehensive income (loss) before reclassifications (19,165 ) 267 4 (18,894 ) Less: gain reclassified from AOCI 695 — — 695 Tax effect — (89 ) — (89 ) Net current-period other comprehensive income (loss) (19,860 ) 178 4 (19,678 ) AOCI balance at June 30, 2017 $ (13,569 ) $ (1,080 ) $ (9 ) $ (14,658 ) Six Months Ended June 30, 2018 Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Available-for-Sale Securities Foreign Currency Items Total AOCI balance at December 31, 2017 $ (20,232 ) $ (2,722 ) $ (7 ) $ (22,961 ) Impact of change in accounting principle (1) — $ (586 ) — $ (586 ) AOCI balance at January 1, 2018 $ (20,232 ) $ (3,308 ) $ (7 ) $ (23,547 ) Other comprehensive income (loss) before reclassifications 14,356 (490 ) (4 ) 13,862 Less: loss reclassified from AOCI (8,444 ) — — (8,444 ) Tax effect — 112 — 112 Net current-period other comprehensive income (loss) 22,800 (378 ) (4 ) 22,418 AOCI balance at June 30, 2018 $ 2,568 $ (3,686 ) $ (11 ) $ (1,129 ) (1) As of January 1, 2018, the Company early adopted the requirements of ASU 2018-02. The amount represents the reclassification from Accumulated Other Comprehensive Income (Loss) to Accumulated Deficit in the first quarter of 2018 related to the adoption of ASU 2018-02. See Note 4 for additional discussion . Six Months Ended June 30, 2017 Unrealized Gains (Losses) on Cash Flow Hedges Unrealized Gains (Losses) on Available-for-Sale Securities Foreign Currency Items Total AOCI balance at December 31, 2016 $ 13,006 $ (178 ) $ (12 ) $ 12,816 Other comprehensive income (loss) before reclassifications (23,364 ) 1,834 3 (21,527 ) Less: gain reclassified from AOCI 3,211 3,252 — 6,463 Tax effect — 516 — 516 Net current-period other comprehensive income (loss) (26,575 ) (902 ) 3 (27,474 ) AOCI balance at June 30, 2017 $ (13,569 ) $ (1,080 ) $ (9 ) $ (14,658 )

REVENUE, CREDIT CONCENTRATION36

REVENUE, CREDIT CONCENTRATIONS AND GEOGRAPHIC INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2018
Concentration Risk And Geographic Information [Abstract]
Disaggregates of Total Revenues from External Customers and Collaborative Partners by Geographic Region	The following table disaggregates Total Revenues from external customers and collaborative partners by geographic region. Net product revenues by geographic region are based on patient location for the Company’s commercial products, except for Aldurazyme. 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 is located in the U.S. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Total revenues by geographic region: United States $ 162,788 $ 141,611 $ 353,360 $ 274,095 Europe 107,221 87,672 212,871 171,577 Latin America 58,158 66,739 96,633 112,035 Rest of world 44,678 21,426 83,428 63,486 Total revenues $ 372,845 $ 317,448 $ 746,292 $ 621,193
Disaggregates of Total Net Product Revenues from External Customers by Product	The following table disaggregates total Net Product Revenues from external customers by product. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net product revenues by product: Aldurazyme $ 24,003 $ 19,985 $ 90,059 $ 39,340 Brineura 10,890 254 17,807 254 Firdapse 5,177 4,855 10,103 8,965 Kuvan 109,045 101,944 208,160 194,290 Naglazyme 91,086 85,751 166,082 166,309 Vimizim 127,585 103,137 244,674 208,958 Total net product revenues $ 367,786 $ 315,926 $ 736,885 $ 618,116
Disaggregates of Total Net Product Revenues Based on Patient Location	The table below disaggregates total Net Product Revenues 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 ’ Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 United States $ 138,411 $ 121,256 $ 262,552 $ 233,962 Europe 104,262 87,672 207,419 171,577 Latin America 58,158 66,738 96,633 112,032 Rest of world 42,952 20,275 80,222 61,205 Total net product revenue marketed by the Company 343,783 295,941 646,826 578,776 Aldurazyme net product revenues marketed by Genzyme 24,003 19,985 90,059 39,340 Total net product revenues $ 367,786 $ 315,926 $ 736,885 $ 618,116
Total Net Product Revenue Concentrations Attributed to Largest Customers	The following table illustrates the percentage of the Company’s total Net Product Revenues attributed to the Company’s largest customers for the three and six months ended June 30, 2018 and 2017. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Customer A 18 % 17 % 18 % 17 % Customer B 7 % 6 % 12 % 6 % Customer C 12 % 14 % 12 % 13 % Customer D 10 % 10 % 9 % 10 % Customer E 4 % 10 % 2 % 7 % Total 51 % 57 % 53 % 53 %

Nature of Operations - Addition

Nature of Operations - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018Product
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of approved commercial products	7

Summary of Significant Accounti

Summary of Significant Accounting Policies - Additional Information (Detail) - Aldurazyme	Jun. 30, 2018
Minimum
Significant Accounting Policies [Line Items]
Payment received as percentage of net product sales	39.50%
Maximum
Significant Accounting Policies [Line Items]
Payment received as percentage of net product sales	50.00%

Recent Accounting Pronounceme39

Recent Accounting Pronouncements - Summary of Adjustments to Accounts on Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands		Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	[1]
ASSETS
Accounts receivable, net		$ 363,566		$ 261,365
Deferred tax assets		425,380		399,095
Total assets		4,624,679		4,633,125
Equity:
Accumulated deficit		(1,677,855)		(1,637,548)
Total liabilities and stockholders' equity		$ 4,624,679		$ 4,633,125
ASC 606
ASSETS
Accounts receivable, net			$ 287,377
Deferred tax assets			393,131
Total assets			4,653,173
Equity:
Accumulated deficit			(1,617,500)
Total liabilities and stockholders' equity			4,653,173
Adjustments | ASC 606 | Tax Provision
ASSETS
Accounts receivable, net	[2]		0
Deferred tax assets	[2]		(5,964)
Total assets	[2]		(5,964)
Equity:
Accumulated deficit	[2]		(5,964)
Total liabilities and stockholders' equity	[2]		(5,964)
Adjustments | ASC 606 | Aldurazyme
ASSETS
Accounts receivable, net	[3]		26,012
Deferred tax assets	[3]		0
Total assets	[3]		26,012
Equity:
Accumulated deficit	[3]		26,012
Total liabilities and stockholders' equity	[3]		$ 26,012
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.
[2]	The adoption of ASC 606 primarily resulted in an acceleration of the variable consideration components of revenue as of December 31, 2017, which in turn generated additional deferred tax liabilities that ultimately reduced the Company's net deferred tax asset position. The tax provision amount has been calculated using the Company’s estimated statutory rate.
[3]	This adjustment represents management’s estimate of the variable consideration to be earned on worldwide sales of Aldurazyme by Genzyme in excess of the product transfer revenue previously recognized for Genzyme’s ending inventory at December 31, 2017. The product transfer revenue previously recognized as revenue represents the fixed amount per unit of Aldurazyme that Genzyme was required to pay the Company if the product was unsold by Genzyme.

Recent Accounting Pronounceme40

Recent Accounting Pronouncements - Summary of Adjustments to Accounts on Condensed Consolidated Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Recent Accounting Pronouncements [Line Items]
Net product revenues		$ 372,845	$ 317,448	$ 746,292		$ 621,193
Benefit from income taxes		(12,385)	(8,713)	(19,040)		(16,729)
Net loss		(16,792)	(36,833)	(60,941)		(53,123)
Net Product Revenues
Recent Accounting Pronouncements [Line Items]
Net product revenues		367,786	$ 315,926	736,885		$ 618,116
Adjustments
Recent Accounting Pronouncements [Line Items]
Benefit from income taxes	[1]	11		(6,225)
Net loss	[1]	37		(20,925)	[2]
Adjustments | Net Product Revenues
Recent Accounting Pronouncements [Line Items]
Net product revenues	[1]	48		(27,150)
Balance Without Adoption of ASC 606
Recent Accounting Pronouncements [Line Items]
Benefit from income taxes		(12,374)		(25,265)
Net loss		(16,755)		(81,866)
Balance Without Adoption of ASC 606 | Net Product Revenues
Recent Accounting Pronouncements [Line Items]
Net product revenues		$ 367,834		$ 709,735
[1]	The adoption of ASC 606 resulted in additional revenues recognized in the first half of 2018, which in turn generated additional deferred tax liabilities that reduced the Company's benefit from income taxes. The Benefit from Income Taxes amount has been calculated using the Company’s estimated statutory rate.
[2]	The adoption of ASC 606 resulted in decreased Net Loss and increased Accounts Receivable, Net due to additional revenues recognized in the first quarter of 2018, which in turn generated additional deferred tax liabilities that reduced the Company's net Deferred Tax Assets. The Deferred Income Taxes amount has been calculated using the Company’s estimated statutory rate.

Recent Accounting Pronounceme41

Recent Accounting Pronouncements - Summary of Adjustments to Accounts on Condensed Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Recent Accounting Pronouncements [Line Items]
Net loss		$ (16,792)	$ (36,833)	$ (60,941)		$ (53,123)
Deferred income taxes				(29,681)		(22,770)
Changes in operating assets and liabilities:
Accounts receivable, net				(77,416)		$ (16,834)
Net cash used in operating activities				(76,366)
Adjustments
Recent Accounting Pronouncements [Line Items]
Net loss	[1]	37		(20,925)	[2]
Deferred income taxes	[2]			(6,225)
Changes in operating assets and liabilities:
Accounts receivable, net	[2]			27,150
Net cash used in operating activities	[2]			0
Balance Without Adoption of ASC 606
Recent Accounting Pronouncements [Line Items]
Net loss		$ (16,755)		(81,866)
Deferred income taxes				(35,906)
Changes in operating assets and liabilities:
Accounts receivable, net				(50,266)
Net cash used in operating activities				$ (76,366)
[1]	The adoption of ASC 606 resulted in additional revenues recognized in the first half of 2018, which in turn generated additional deferred tax liabilities that reduced the Company's benefit from income taxes. The Benefit from Income Taxes amount has been calculated using the Company’s estimated statutory rate.
[2]	The adoption of ASC 606 resulted in decreased Net Loss and increased Accounts Receivable, Net due to additional revenues recognized in the first quarter of 2018, which in turn generated additional deferred tax liabilities that reduced the Company's net Deferred Tax Assets. The Deferred Income Taxes amount has been calculated using the Company’s estimated statutory rate.

Recent Accounting Pronounceme42

Recent Accounting Pronouncements - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
ASU 2018-02
Recent Accounting Pronouncements [Line Items]
Reclassification from AOCI to accumulated deficit	$ 0.6

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	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
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	23,950	20,058	23,950	20,058
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	7,829	8,440	7,829	8,440
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	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	3,983
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	3,970	0
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	3,544	3,041	3,544	3,041
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	433	387	433	387
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	208	224	208	224

Net Loss Per Common Share - Add

Net Loss Per Common Share - Additional Information (Detail)	Jun. 30, 2018$ / shares
Convertible Notes due 2018
Earnings Per Share [Line Items]
Debt instrument, interest rate, stated percentage, per annum	0.75%
Percentage of capped call transactions to principal amount	50.00%
Convertible Notes due 2020
Earnings Per Share [Line Items]
Debt instrument, interest rate, stated percentage, per annum	1.50%
Percentage of capped call transactions to principal amount	50.00%
Convertible Notes due 2018 and due 2020
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price, per share	$ 94.15

Schedule of Cash, Cash Equivale

Schedule of Cash, Cash Equivalents and Available-for-Sale Securities by Significant Investment Category (Detail) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017		Jun. 30, 2017	Dec. 31, 2016
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Amortized Cost		$ 1,647,842	$ 1,786,045
Gross Unrealized Gains		291	300
Gross Unrealized Losses		(5,072)	(4,592)
Fair Value		1,643,061	1,781,753
Cash and Cash Equivalents		427,411	598,028	[1]	$ 354,864	$ 408,330
Short-term Marketable Securities	[2]	935,662	797,940
Long-term Marketable Securities	[3]	279,988	385,785
Level 1 | Cash
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Cash		209,062	340,253
Gross Unrealized Gains		0	0
Gross Unrealized Losses		0	0
Cash and Cash Equivalents		209,062	340,253
Short-term Marketable Securities	[2]	0	0
Long-term Marketable Securities	[3]	0	0
Level 2
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Amortized Cost		1,438,780	1,445,792
Gross Unrealized Gains		291	300
Gross Unrealized Losses		(5,072)	(4,592)
Fair Value		1,433,999	1,441,500
Cash and Cash Equivalents		218,349	257,775
Short-term Marketable Securities	[2]	935,662	797,940
Long-term Marketable Securities	[3]	279,988	385,785
Level 2 | Money Market Instruments
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Amortized Cost		177,882	215,441
Gross Unrealized Gains		0	0
Gross Unrealized Losses		0	0
Fair Value		177,882	215,441
Cash and Cash Equivalents		177,882	215,441
Short-term Marketable Securities	[2]	0	0
Long-term Marketable Securities	[3]	0	0
Level 2 | Corporate Debt Securities
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Amortized Cost		643,979	707,652
Gross Unrealized Gains		136	150
Gross Unrealized Losses		(3,452)	(2,553)
Fair Value		640,663	705,249
Cash and Cash Equivalents		7,708	3,096
Short-term Marketable Securities	[2]	411,185	406,188
Long-term Marketable Securities	[3]	221,770	295,965
Level 2 | Commercial Paper
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Amortized Cost		51,818	24,566
Gross Unrealized Gains		1	0
Gross Unrealized Losses		0	0
Fair Value		51,819	24,566
Cash and Cash Equivalents		18,947	2,751
Short-term Marketable Securities	[2]	32,871	21,815
Long-term Marketable Securities	[3]	0	0
Level 2 | U.S. Government Agency Securities
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Amortized Cost		532,066	472,593
Gross Unrealized Gains		4	0
Gross Unrealized Losses		(1,597)	(1,975)
Fair Value		530,473	470,618
Cash and Cash Equivalents		11,312	35,497
Short-term Marketable Securities	[2]	461,143	345,501
Long-term Marketable Securities	[3]	58,019	89,620
Level 2 | Foreign and Other
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Amortized Cost		33,035	25,540
Gross Unrealized Gains		150	150
Gross Unrealized Losses		(23)	(64)
Fair Value		33,162	25,626
Cash and Cash Equivalents		2,500	990
Short-term Marketable Securities	[2]	30,463	24,436
Long-term Marketable Securities	[3]	$ 199	$ 200
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.
[2]	The Company’s short-term marketable securities mature in one year or less.
[3]	The Company’s long-term marketable securities mature between one and five years.

Schedule of Cash, Cash Equiva46

Schedule of Cash, Cash Equivalents and Available-for-Sale Securities by Significant Investment Category (Parenthetical) (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Minimum
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Long-term marketable securities maturity period	1 year	1 year
Maximum
Schedule Of Cash Cash Equivalents And Available For Sale Securities [Line Items]
Short-term marketable securities maturity period	1 year	1 year
Long-term marketable securities maturity period	5 years	5 years

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018USD ($)
Investments Debt And Equity Securities [Abstract]
Other- than- temporary impairment	$ 0

Intangible Assets (Detail)

Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Intangible assets:
Finite-lived intangible assets	$ 303,298	$ 303,298
Indefinite-lived intangible assets	326,359	326,359
Gross intangible assets:	629,657	629,657
Less: Accumulated amortization	(127,362)	(112,147)
Net carrying value	$ 502,295	$ 517,510	[1]
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail)	3 Months Ended
	Jun. 30, 2018USD ($)
Medivation
Goodwill And Intangible Assets [Line Items]
Milestone payments received	$ 20,000,000
IPR&D
Goodwill And Intangible Assets [Line Items]
Amount reclassified to definite-lived intangible assets	0
Impairment charges on definite-lived intangible assets	$ 0

Schedule of Property Plant and

Schedule of Property Plant and Equipment Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,341,136	$ 1,303,434
Accumulated depreciation	(440,656)	(406,734)
Total property, plant and equipment, net	900,480	896,700	[1]
Building and Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	674,682	663,347
Manufacturing and Laboratory Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	316,331	294,521
Computer Hardware and Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	152,010	144,268
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	38,352	42,572
Furniture and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	30,833	31,515
Land Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,977	5,331
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	62,369	62,369
Construction-in-Progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 60,582	$ 59,511
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.

Property Plant and Equipment -

Property Plant and Equipment - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property Plant And Equipment [Abstract]
Depreciation expense	$ 20.1	$ 17.9	$ 40.1	$ 35.4
Depreciation capitalized into inventory	$ 6.6	$ 6.2	$ 10.5	$ 11.8

Schedule of Inventory (Detail)

Schedule of Inventory (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 46,537	$ 49,877
Work-in-process	234,370	234,674
Finished goods	192,449	191,224
Total inventory	$ 473,356	$ 475,775	[1]
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.

Schedule of Accounts Payable an

Schedule of Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Accounts payable and accrued operating expenses	$ 166,416	$ 166,616
Accrued compensation expense	94,954	140,781
Accrued rebates payable	50,944	36,472
Accrued royalties payable	18,620	18,820
Value added taxes payable	9,191	9,740
Forward foreign currency exchange contracts	7,165	14,464
Accrued income taxes	2,658	5,528
Other	8,784	9,500
Total accounts payable and accrued liabilities	$ 358,732	$ 401,921	[1]
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Convertible notes outstanding	$ 1,191,623,000	$ 1,174,470,000
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 100,000,000
Maturity date of convertible debt	Nov. 29, 2018
Letter of credit subfacility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 10,000,000
Swingline loan subfacility
Debt Instrument [Line Items]
Maximum borrowing capacity	15,000,000
Credit Facility [Member]
Debt Instrument [Line Items]
Outstanding amount	$ 0	$ 0

Summary of Convertible Debt (De

Summary of Convertible Debt (Detail) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Convertible Notes, net of unamortized discount and deferred offering costs		$ 369,752	$ 360,949	[1]
Convertible Notes, net of unamortized discount and deferred offering costs		821,871	813,521	[1]
Total convertible debt, net		1,191,623	1,174,470
Convertible Notes, fair value		1,343,623	1,344,319
0.75% Senior Subordinated Convertible Notes Due in October 2018
Debt Instrument [Line Items]
Convertible Notes		374,980	374,980
Convertible debt, unamortized discount		(4,659)	(12,488)
Convertible debt, Unamortized deferred offering costs		(569)	(1,543)
Convertible Notes, net of unamortized discount and deferred offering costs		369,752	360,949
Convertible Notes, fair value	[2]	398,874	403,955
1.50% Senior Subordinated Convertible Notes Due in October 2020
Debt Instrument [Line Items]
Convertible Notes		374,993	374,993
Convertible debt, unamortized discount		(33,531)	(40,287)
Convertible debt, Unamortized deferred offering costs		(2,983)	(3,631)
Convertible Notes, net of unamortized discount and deferred offering costs		338,479	331,075
Convertible Notes, fair value	[2]	442,240	446,470
0.599% Senior Subordinated Convertible Notes Due in August 2024
Debt Instrument [Line Items]
Convertible Notes		495,000	495,000
Convertible debt, unamortized discount		(8,651)	(9,355)
Convertible debt, Unamortized deferred offering costs		(2,957)	(3,199)
Convertible Notes, net of unamortized discount and deferred offering costs		483,392	482,446
Convertible Notes, fair value	[2]	$ 502,509	$ 493,894
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.
[2]	The fair value of the Company’s fixed-rate convertible debt is based on open market trades and is classified as Level 1 in the fair value hierarchy. See Note 12 to these Condensed Consolidated Financial Statements for additional information related to the Company’s fair value measurements.

Summary of Convertible Debt (Pa

Summary of Convertible Debt (Parenthetical) (Detail)	Jun. 30, 2018
0.75% Senior Subordinated Convertible Notes Due in October 2018
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	0.75%
1.50% Senior Subordinated Convertible Notes Due in October 2020
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	1.50%
0.599% Senior Subordinated Convertible Notes Due in August 2024
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	0.599%

Summary of Interest Expense on

Summary of Interest Expense on Convertible Debt (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule Of Interest Expenses [Line Items]
Total interest expense on convertible debt	$ 12,225	$ 10,040	$ 23,787	$ 20,159
Convertible Senior Notes
Schedule Of Interest Expenses [Line Items]
Coupon interest expense	3,527	2,194	6,488	4,558
Amortization of debt issuance costs	1,006	886	2,010	1,772
Accretion of discount on convertible notes	7,692	6,960	15,289	13,829
Total interest expense on convertible debt	$ 12,225	$ 10,040	$ 23,787	$ 20,159

Summary of Designated Forward F

Summary of Designated Forward Foreign Currency Exchange Contracts Outstanding (Detail) - Foreign exchange contracts	6 Months Ended
	Jun. 30, 2018BRL (R$)Derivative	Jun. 30, 2018CAD ($)Derivative	Jun. 30, 2018COP ($)Derivative	Jun. 30, 2018EUR (€)Derivative
Maximum
Derivative [Line Items]
Maturity	Jun. 30, 2021
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Number of Contracts	522	522	522	522
Derivatives Designated As Hedging Instruments | Euros | Purchase
Derivative [Line Items]
Number of Contracts	108	108	108	108
Aggregate Notional Amount in Foreign Currency | €				€ 134,400,000
Derivatives Designated As Hedging Instruments | Euros | Sell
Derivative [Line Items]
Number of Contracts	394	394	394	394
Aggregate Notional Amount in Foreign Currency | €				€ 488,200,000
Derivatives Designated As Hedging Instruments | Euros | Minimum | Purchase
Derivative [Line Items]
Maturity	Jul. 31, 2018
Derivatives Designated As Hedging Instruments | Euros | Minimum | Sell
Derivative [Line Items]
Maturity	Jul. 31, 2018
Derivatives Designated As Hedging Instruments | Euros | Maximum | Purchase
Derivative [Line Items]
Maturity	Jun. 30, 2021
Derivatives Designated As Hedging Instruments | Euros | Maximum | Sell
Derivative [Line Items]
Maturity	Jun. 30, 2021
Derivatives Designated As Hedging Instruments | Canadian Dollars | Sell
Derivative [Line Items]
Number of Contracts	12	12	12	12
Aggregate Notional Amount in Foreign Currency | $		$ 15,000,000
Derivatives Designated As Hedging Instruments | Canadian Dollars | Minimum | Sell
Derivative [Line Items]
Maturity	Jul. 31, 2018
Derivatives Designated As Hedging Instruments | Canadian Dollars | Maximum | Sell
Derivative [Line Items]
Maturity	Dec. 31, 2018
Derivatives Designated As Hedging Instruments | Colombian Pesos | Sell
Derivative [Line Items]
Number of Contracts	6	6	6	6
Aggregate Notional Amount in Foreign Currency | $			$ 48,000,000,000
Derivatives Designated As Hedging Instruments | Colombian Pesos | Minimum | Sell
Derivative [Line Items]
Maturity	Jul. 31, 2018
Derivatives Designated As Hedging Instruments | Colombian Pesos | Maximum | Sell
Derivative [Line Items]
Maturity	Dec. 31, 2018
Derivatives Designated As Hedging Instruments | Brazilian Reais | Sell
Derivative [Line Items]
Number of Contracts	2	2	2	2
Aggregate Notional Amount in Foreign Currency | R$	R$ 143800000
Maturity	Aug. 31, 2018

Derivative Instruments and He59

Derivative Instruments and Hedging Strategies - Additional Information (Detail) - Foreign Currency Derivatives $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Derivative [Line Items]
Amount reclassified from accumulated other comprehensive loss to earnings as related to forecasted revenue and operating expense transactions	$ 2.2
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	Jun. 30, 2021

Summary of Non-Designated Forwa

Summary of Non-Designated Forward Foreign Currency Exchange Contracts Outstanding (Detail) - Foreign exchange contracts	6 Months Ended
	Jun. 30, 2018BRL (R$)Derivative	Jun. 30, 2018COP ($)Derivative	Jun. 30, 2018EUR (€)Derivative	Jun. 30, 2018GBP (£)Derivative
Maximum
Derivative [Line Items]
Maturity	Jun. 30, 2021
Not Designated as Hedging Instrument
Derivative [Line Items]
Number of Contracts	10	10	10	10
Not Designated as Hedging Instrument | Euros | Purchase
Derivative [Line Items]
Number of Contracts	3	3	3	3
Aggregate Notional Amount in Foreign Currency | €			€ 52,200,000
Maturity	Jul. 31, 2018
Not Designated as Hedging Instrument | Brazilian Reais | Purchase
Derivative [Line Items]
Number of Contracts	5	5	5	5
Aggregate Notional Amount in Foreign Currency | R$	R$ 52200000
Maturity	Aug. 31, 2018
Not Designated as Hedging Instrument | United Kingdom, Pounds | Sell
Derivative [Line Items]
Number of Contracts	1	1	1	1
Aggregate Notional Amount in Foreign Currency | £				£ 2,600,000
Maturity	Jul. 31, 2018
Not Designated as Hedging Instrument | Colombian Pesos | Sell
Derivative [Line Items]
Number of Contracts	1	1	1	1
Aggregate Notional Amount in Foreign Currency | $		$ 34,000,000,000
Maturity	Jul. 31, 2018

Fair Value Carrying Amount of D

Fair Value Carrying Amount of Derivative Instruments (Detail) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative Asset, Fair Value	[1]	$ 15,891	$ 9,663
Derivative Liability, Fair Value	[1]	11,736	27,150
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Derivative Asset, Fair Value	[1]	14,451	8,988
Derivative Liability, Fair Value	[1]	11,179	27,106
Derivatives Designated As Hedging Instruments | Forward Foreign Currency Exchange Contracts | Other Current Assets
Derivative [Line Items]
Derivative Asset, Fair Value	[1]	8,599	4,015
Derivatives Designated As Hedging Instruments | Forward Foreign Currency Exchange Contracts | Other Assets
Derivative [Line Items]
Derivative Asset, Fair Value	[1]	5,852	4,973
Derivatives Designated As Hedging Instruments | Forward Foreign Currency Exchange Contracts | Accounts Payable and Accrued Liabilities
Derivative [Line Items]
Derivative Liability, Fair Value	[1]	6,608	14,420
Derivatives Designated As Hedging Instruments | Forward Foreign Currency Exchange Contracts | Other Long-Term Liabilities
Derivative [Line Items]
Derivative Liability, Fair Value	[1]	4,571	12,686
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Fair Value	[1]	1,440	675
Derivative Liability, Fair Value	[1]	557	44
Not Designated as Hedging Instrument | Forward Foreign Currency Exchange Contracts | Other Current Assets
Derivative [Line Items]
Derivative Asset, Fair Value	[1]	1,440	675
Not Designated as Hedging Instrument | Forward Foreign Currency Exchange Contracts | Accounts Payable and Accrued Liabilities
Derivative [Line Items]
Derivative Liability, Fair Value	[1]	$ 557	$ 44
[1]	See Note 12 to these Condensed Consolidated Financial Statements for additional information related to the Company’s fair value measurements.

Effect of Derivative Instrument

Effect of Derivative Instruments (Detail) - Forward Foreign Currency Exchange Contracts - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivatives Designated As Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) recognized in accumulated other comprehensive loss	[1]	$ 23,582	$ (19,165)	$ 14,356	$ (23,364)
Net gain (loss) reclassified from accumulated other comprehensive income (loss) into earnings	[2]	(2,659)	695	(8,444)	3,211
Net gain (loss) recognized in net loss	[3]	(4,238)	5,373	2,985	5,631
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) recognized in net loss	[4]	$ 2,700	$ 826	$ 2,322	$ 1,706
[1]	Net change in the fair value of the effective portion classified as accumulated other comprehensive loss.
[2]	Effective portion classified as Net Product Revenues and Operating expenses.
[3]	Classified as Operating expenses.
[4]	Ineffective portion and amount excluded from effectiveness testing classified as Operating expenses.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets		$ 8,739	$ 16,614
Fair value of other non-current assets		21,337	11,859
Fair value of financial assets, Total		30,076	28,473
Fair value of other current liabilities		78,534	55,971
Fair value of other non-current liabilities		89,094	165,449
Fair value of financial liabilities, Total		167,628	221,420
Contingent Acquisition Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities		76,466	53,648
Fair value of other non-current liabilities		57,674	135,318
NQDC Plan Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities		2,068	2,323
Fair value of other non-current liabilities		31,420	30,131
Restricted Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	[1]	7,721	15,647
Fair value of other non-current assets	[1]	6,889
Strategic Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	[2]	1,616
NQDC Plan Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets		1,018	967
Fair value of other non-current assets		12,832	11,859
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		1,616	0
Fair value of financial assets, Total		1,616	0
Fair value of other current liabilities		1,050	1,356
Fair value of other non-current liabilities		18,588	18,272
Fair value of financial liabilities, Total		19,638	19,628
Quoted Price In Active Markets For Identical Assets (Level 1) | Contingent Acquisition Consideration
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
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		1,050	1,356
Fair value of other non-current liabilities		18,588	18,272
Quoted Price In Active Markets For Identical Assets (Level 1) | Restricted Investments
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
Quoted Price In Active Markets For Identical Assets (Level 1) | Strategic Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	[2]	1,616
Quoted Price In Active Markets For Identical Assets (Level 1) | NQDC Plan Assets
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
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		8,739	16,614
Fair value of other non-current assets		19,721	11,859
Fair value of financial assets, Total		28,460	28,473
Fair value of other current liabilities		1,018	967
Fair value of other non-current liabilities		12,832	11,859
Fair value of financial liabilities, Total		13,850	12,826
Significant Other Observable Inputs (Level 2) | Contingent Acquisition Consideration
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
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		1,018	967
Fair value of other non-current liabilities		12,832	11,859
Significant Other Observable Inputs (Level 2) | Restricted Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets	[1]	7,721	15,647
Fair value of other non-current assets	[1]	6,889
Significant Other Observable Inputs (Level 2) | Strategic Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	[2]	0
Significant Other Observable Inputs (Level 2) | NQDC Plan Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current assets		1,018	967
Fair value of other non-current assets		12,832	11,859
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 of financial assets, Total		0	0
Fair value of other current liabilities		76,466	53,648
Fair value of other non-current liabilities		57,674	135,318
Fair value of financial liabilities, Total		134,140	188,966
Significant Unobservable Inputs (Level 3) | Contingent Acquisition Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other current liabilities		76,466	53,648
Fair value of other non-current liabilities		57,674	135,318
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
Significant Unobservable Inputs (Level 3) | Restricted Investments
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
Significant Unobservable Inputs (Level 3) | Strategic Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of other non-current assets	[2]	0
Significant Unobservable Inputs (Level 3) | NQDC Plan Assets
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
[1]	The restricted investments at June 30, 2018 and December 31, 2017 secure the Company’s irrevocable standby letters of credit obtained in connection with certain commercial agreements.
[2]	The Company has 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 Consolidated Balance Sheets.

Liabilities Measured at Fair Va

Liabilities Measured at Fair Value Using Level 3 Inputs (Detail) - Contingent Payment $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent acquisition consideration, Beginning balance	$ 188,966
Changes in the fair value of other contingent acquisition consideration	8,284
Foreign exchange remeasurement of Euro denominated contingent acquisition consideration	(1,503)
Contingent acquisition consideration, Ending balance	134,140
Merck Serono
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Milestone payments to Ares Trading S.A.	$ (61,607)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Asset retirement obligations	$ 4.2	$ 4.2

Compensation Expense (Detail)

Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 38,606	$ 40,101	$ 75,214	$ 70,775
Cost of Sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	3,246	2,510	6,386	4,796
R&D
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	15,573	14,647	28,842	26,141
Selling, General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 19,787	$ 22,944	$ 39,986	$ 39,838

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense capitalized to inventory		$ 5.4	$ 4.4	$ 9	$ 7.6
Shares, granted				775,380
Weighted-average fair value per share granted				$ 33.34
Restricted Stock With Service Based Vesting Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, granted				1,519,780
Weighted-average fair value per RSU granted				$ 84.19
March 2018 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value per RSU granted	$ 83.57
Granted restricted stock units	129,680
Award vesting service period	3 years
Percentage of threshold achievement	70.00%
Percentage of ceiling achievement	125.00%
March 2018 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%
March 2018 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%

Assumptions Used to Estimate Pe

Assumptions Used to Estimate Per Share Fair Value of Stock Options Granted (Detail) - Stock Option	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	38.40%	37.80%	37.80%	37.60%
Expected volatility, maximum		39.60%	38.40%	39.70%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Expected life	5 years 8 months 12 days			6 years 10 months 24 days
Risk-free interest rate	2.70%
Risk-free interest rate, minimum		1.80%	2.30%	1.80%
Risk-free interest rate, maximum		1.90%	2.70%	2.20%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life		5 years	4 years 7 months 6 days	5 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life		6 years 7 months 6 days	5 years 8 months 12 days	6 years 7 months 6 days

Assumptions Used to Estimate 69

Assumptions Used to Estimate Per Share Fair Value of Stock Purchase Rights (Detail) - Employee Stock Purchase Plan	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility, minimum	29.70%	30.70%	29.70%	30.70%
Expected volatility, maximum	33.30%	42.30%	33.30%	42.30%
Dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate, minimum	1.20%	1.00%	1.20%	1.00%
Risk-free interest rate, maximum	2.50%	1.30%	2.50%	1.30%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	6 months	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	24 months

Summary of Restricted Stock Uni

Summary of Restricted Stock Unit Awards with Performance Conditions (Detail)	1 Months Ended
	Mar. 31, 2018$ / sharesshares	Mar. 31, 2017$ / sharesshares	Mar. 31, 2016$ / sharesshares	Mar. 31, 2015$ / sharesshares
March 2018 Base Restricted Stock Unit Awards with Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Base RSUs Granted	129,680
Grant Date Fair Value per RSU | $ / shares	$ 83.57
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		1.03
RSUs Earned		132,548
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			1.03
RSUs Earned			134,219
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				1.11
RSUs Earned				64,713

Amounts Reclassified out of AOC

Amounts Reclassified out of AOCI (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total revenues	$ 372,845	$ 317,448	$ 746,292	$ 621,193
LOSS FROM OPERATIONS	(25,263)	(38,812)	(69,635)	(59,020)
Other income	2,849	543	2,677	4,015
Benefit from income taxes	(12,385)	(8,713)	(19,040)	(16,729)
NET LOSS	(16,792)	(36,833)	(60,941)	(53,123)
Net Product Revenues
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total revenues	367,786	315,926	736,885	618,116
Reclassified out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Benefit from income taxes	0	0	0	(1,181)
NET LOSS	(2,659)	695	(8,444)	5,282
Reclassified out of Accumulated Other Comprehensive Income | Gains (losses) on Cash Flow Hedges
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
LOSS FROM OPERATIONS	(2,659)	695	(8,444)	3,211
Reclassified out of Accumulated Other Comprehensive Income | Gains (losses) on Cash Flow Hedges | Forward Foreign Currency Exchange Contracts
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Operating expenses	1,403	(424)	3,264	(1,450)
Reclassified out of Accumulated Other Comprehensive Income | Gains (losses) on Cash Flow Hedges | Net Product Revenues | Forward Foreign Currency Exchange Contracts
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total revenues	(4,062)	1,119	(11,708)	4,661
Reclassified out of Accumulated Other Comprehensive Income | Gain on Sale of Available-for-Sale Debt Securities
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other income	0	0	0	3,252
Total gain on available-for-sale debt securities	$ 0	$ 0	$ 0	$ 2,071

Summary of Changes in Accumulat

Summary of Changes in Accumulated Balances of AOCI Including Current Period Other Comprehensive Income (Loss) and Reclassifications Out of AOCI (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	[1]			$ 2,808,663
Adjusted balance at January 1, 2018				2,828,711
Other comprehensive income (loss) before reclassifications		$ 25,108	$ (18,894)	13,862	$ (21,527)
Less: net gain (loss) reclassified from AOCI		(2,659)	695	(8,444)	6,463
Tax effect		(351)	(89)	112	516
Net current-period other comprehensive income (loss)		27,416	(19,678)	22,418	(27,474)
Ending Balance		2,885,104		2,885,104
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(23,673)	6,291	(20,232)	13,006
Impact of change in accounting principle	[2]			0
Adjusted balance at January 1, 2018				(20,232)
Other comprehensive income (loss) before reclassifications		23,582	(19,165)	14,356	(23,364)
Less: net gain (loss) reclassified from AOCI		(2,659)	695	(8,444)	3,211
Tax effect		0	0	0	0
Net current-period other comprehensive income (loss)		26,241	(19,860)	22,800	(26,575)
Ending Balance		2,568	(13,569)	2,568	(13,569)
Unrealized Gains (Losses) on Available-for-Sale Debt Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(4,866)	(1,258)	(2,722)	(178)
Impact of change in accounting principle	[2]			(586)
Adjusted balance at January 1, 2018				(3,308)
Other comprehensive income (loss) before reclassifications		1,531	267	(490)	1,834
Less: net gain (loss) reclassified from AOCI		0	0	0	3,252
Tax effect		(351)	(89)	112	516
Net current-period other comprehensive income (loss)		1,180	178	(378)	(902)
Ending Balance		(3,686)	(1,080)	(3,686)	(1,080)
Foreign Currency Items
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(6)	(13)	(7)	(12)
Impact of change in accounting principle	[2]			0
Adjusted balance at January 1, 2018				(7)
Other comprehensive income (loss) before reclassifications		(5)	4	(4)	3
Less: net gain (loss) reclassified from AOCI		0	0	0	0
Tax effect		0	0	0	0
Net current-period other comprehensive income (loss)		(5)	4	(4)	3
Ending Balance		(11)	(9)	(11)	(9)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(28,545)	5,020	(22,961)	12,816
Impact of change in accounting principle	[2]			(586)
Adjusted balance at January 1, 2018				(23,547)
Ending Balance		$ (1,129)	$ (14,658)	$ (1,129)	$ (14,658)
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.
[2]	As of January 1, 2018, the Company early adopted the requirements of ASU 2018-02. The amount represents the reclassification from Accumulated Other Comprehensive Income (Loss) to Accumulated Deficit in the first quarter of 2018 related to the adoption of ASU 2018-02. See Note 4 for additional discussion

Revenue, Credit Concentration73

Revenue, Credit Concentrations and Geographic Information - Additional Information (Detail) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018USD ($)SegmentCustomer	Dec. 31, 2017USD ($)Customer
Concentration Risk And Geographic Information [Line Items]
Number of operating business segment | Segment	1
Accounts receivable, net	$ 363,566	$ 261,365	[1]
Largest Customers
Concentration Risk And Geographic Information [Line Items]
Accounts receivable, net	$ 85,000	$ 18,100
Accounts Receivable | Largest Customers
Concentration Risk And Geographic Information [Line Items]
Number of customers accounted for largest balance in accounts receivable | Customer	2	2
Geographic Concentration Risk | Net Product Revenue | Minimum
Concentration Risk And Geographic Information [Line Items]
Concentration risk, percentage	10.00%
Credit Concentration Risk | Accounts Receivable | Larger Customer One
Concentration Risk And Geographic Information [Line Items]
Concentration risk, percentage	30.00%	21.00%
Credit Concentration Risk | Accounts Receivable | Larger Customer Two
Concentration Risk And Geographic Information [Line Items]
Concentration risk, percentage	15.00%	18.00%
[1]	December 31, 2017 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 26, 2018.

Disaggregates of Total Revenues

Disaggregates of Total Revenues from External Customers and Collaborative Partners by Geographic Region (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue from External Customer [Line Items]
Total revenues	$ 372,845	$ 317,448	$ 746,292	$ 621,193
United States
Revenue from External Customer [Line Items]
Total revenues	162,788	141,611	353,360	274,095
Europe
Revenue from External Customer [Line Items]
Total revenues	107,221	87,672	212,871	171,577
Latin America
Revenue from External Customer [Line Items]
Total revenues	58,158	66,739	96,633	112,035
Rest of World
Revenue from External Customer [Line Items]
Total revenues	$ 44,678	$ 21,426	$ 83,428	$ 63,486

Disaggregates of Total Net Prod

Disaggregates of Total Net Product Revenues from External Customers by Product (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue from External Customer [Line Items]
Net product revenues	$ 372,845	$ 317,448	$ 746,292	$ 621,193
Aldurazyme
Revenue from External Customer [Line Items]
Net product revenues	24,003	19,985	90,059	39,340
Brineura
Revenue from External Customer [Line Items]
Net product revenues	10,890	254	17,807	254
Firdapse
Revenue from External Customer [Line Items]
Net product revenues	5,177	4,855	10,103	8,965
Kuvan
Revenue from External Customer [Line Items]
Net product revenues	109,045	101,944	208,160	194,290
Naglazyme
Revenue from External Customer [Line Items]
Net product revenues	91,086	85,751	166,082	166,309
Vimizim
Revenue from External Customer [Line Items]
Net product revenues	127,585	103,137	244,674	208,958
Net Product Revenues
Revenue from External Customer [Line Items]
Net product revenues	$ 367,786	$ 315,926	$ 736,885	$ 618,116

Disaggregates of Total Net Pr76

Disaggregates of Total Net Product Revenues Based on Patient Location (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation Of Revenue [Line Items]
Net product revenues	$ 372,845	$ 317,448	$ 746,292	$ 621,193
United States
Disaggregation Of Revenue [Line Items]
Net product revenues	162,788	141,611	353,360	274,095
Europe
Disaggregation Of Revenue [Line Items]
Net product revenues	107,221	87,672	212,871	171,577
Latin America
Disaggregation Of Revenue [Line Items]
Net product revenues	58,158	66,739	96,633	112,035
Rest of World
Disaggregation Of Revenue [Line Items]
Net product revenues	44,678	21,426	83,428	63,486
Aldurazyme
Disaggregation Of Revenue [Line Items]
Net product revenues	24,003	19,985	90,059	39,340
Net Product Revenues
Disaggregation Of Revenue [Line Items]
Net product revenues	367,786	315,926	736,885	618,116
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, and Vimizim
Disaggregation Of Revenue [Line Items]
Net product revenues	343,783	295,941	646,826	578,776
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, and Vimizim | United States
Disaggregation Of Revenue [Line Items]
Net product revenues	138,411	121,256	262,552	233,962
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, and Vimizim | Europe
Disaggregation Of Revenue [Line Items]
Net product revenues	104,262	87,672	207,419	171,577
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, and Vimizim | Latin America
Disaggregation Of Revenue [Line Items]
Net product revenues	58,158	66,738	96,633	112,032
Marketed by Company | Brineura, Firdapse, Kuvan, Naglazyme, and Vimizim | Rest of World
Disaggregation Of Revenue [Line Items]
Net product revenues	42,952	20,275	80,222	61,205
Marketed by Genzyme | Aldurazyme
Disaggregation Of Revenue [Line Items]
Net product revenues	$ 24,003	$ 19,985	$ 90,059	$ 39,340

Total Net Product Revenue Conce

Total Net Product Revenue Concentrations Attributed to Largest Customers (Detail) - Customer Concentration Risk - Net Product Revenue	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Concentration Risk [Line Items]
Concentration risk, percentage	51.00%	57.00%	53.00%	53.00%
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	18.00%	17.00%	18.00%	17.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	7.00%	6.00%	12.00%	6.00%
Customer C
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%	14.00%	12.00%	13.00%
Customer D
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%	10.00%	9.00%	10.00%
Customer E
Concentration Risk [Line Items]
Concentration risk, percentage	4.00%	10.00%	2.00%	7.00%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	Apr. 27, 2018	Jun. 30, 2018	Jun. 30, 2017
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones		$ 540,400
Contingent consideration		134,100
Contingent acquisition consideration	$ 61,600	43,108	$ 1,894
Purchase commitment for the next five years		62,000
Merck Serono
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones		158,000
Completed Programs | Merck Serono
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones		$ 53,200

Benefit From Income Taxes - Add

Benefit From Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Corporate income tax rate		21.00%	35.00%
Amount for remeasurement of deferred taxes	$ 4.6