Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income (loss)	$ 249,548	$ (36,102)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Stock-based compensation expense	68,982	55,472
Depreciation and amortization expense	14,850	16,415
Deferred income taxes	1,212	2,060
Impairment of property and equipment	1,946	0
Other non-cash items, net	(5,152)	(3,835)
Changes in operating assets and liabilities:
Accounts receivable, net	(5,118)	(2,512)
Inventories	(3,650)	(4,771)
Prepaid expenses and other assets	(47,178)	(7,325)
Accounts payable	717	(343)
Accrued expenses and other liabilities	(9,931)	(29,922)
Accrued restructuring expense	305	(1,459)
Deferred revenues	(839)	(2,815)
Net cash provided by (used in) operating activities	265,692	(15,137)
Cash flows from investing activities:
Purchases of marketable securities	(248,273)	(224,624)
Maturities of marketable securities	98,393	131,173
Expenditures for property and equipment	(11,159)	(11,974)
Decrease in restricted cash and cash equivalents (VIE)	3,198	2,637
(Increase) decrease in other assets	60	80
Net cash used in investing activities	(157,781)	(102,708)
Cash flows from financing activities:
Issuances of common stock under benefit plans	11,249	8,846
Payments on revolving credit facility	(300,000)	0
Advance from collaborator	5,000	0
Payments on capital lease obligations	(4,703)	(4,041)
Payments on construction financing lease obligation	(117)	(103)
Repayments of advanced funding	(994)	0
Net cash (used in) provided by financing activities	(289,565)	4,702
Effect of changes in exchange rates on cash	1,388	2,620
Net decrease in cash and cash equivalents	(180,266)	(110,523)
Cash and cash equivalents—beginning of period	1,183,945	714,768
Cash and cash equivalents—end of period	1,003,679	604,245
Supplemental disclosure of cash flow information:
Cash paid for interest	17,527	20,603
Cash paid for income taxes	1,164	581
Capitalization of costs related to construction financing lease obligation	12,549	0
Issuances of common stock from employee benefit plans receivable	$ 19,847	$ 593