Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income (loss)	$ 562,007	$ (10,550)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Stock-based compensation expense	246,104	216,990
Depreciation expense	53,594	44,965
Write-downs of inventories to net realizable value	13,089	11,138
Deferred income taxes	3,595	(113,969)
Unrealized gain on equity securities	(88,217)	0
Intangible asset impairment charge	0	255,340
Acquired in-process research and development	0	160,000
Deconsolidation of VIE	0	76,644
Other non-cash items, net	10,701	(2,841)
Changes in operating assets and liabilities:
Accounts receivable, net	(75,167)	(60,165)
Inventories	(24,461)	(30,226)
Prepaid expenses and other assets	31,797	(84,296)
Accounts payable	23,023	6,925
Accrued expenses and other liabilities	199,643	147,476
Net cash provided by operating activities	955,708	617,431
Cash flows from investing activities:
Purchases of available-for-sale debt securities	(329,367)	(431,653)
Maturities of available-for-sale debt securities	308,406	247,149
Expenditures for property and equipment	(79,803)	(56,437)
Decrease in “Restricted cash and cash equivalents (VIE)” due to deconsolidation	0	(61,602)
Investment in equity securities	(60,490)	0
Purchase of in-process research and development	0	(160,000)
Net cash used in investing activities	(161,254)	(462,543)
Cash flows from financing activities:
Issuances of common stock under benefit plans	245,754	298,205
Repurchase of common stock	(207,038)	0
Payments on revolving credit facility	0	(300,000)
Advance from collaborator	7,500	10,000
Payments on capital lease obligations	(19,792)	(14,188)
Proceeds from capital lease financing	3,417	0
Proceeds related to construction financing lease obligation	9,566	4,700
Payments on construction financing lease obligation	(4,866)	(412)
Repayments of advanced funding	(3,714)	(3,132)
Other financing activities	(1,000)	0
Net cash provided by (used in) financing activities	29,827	(4,827)
Effect of changes in exchange rates on cash	(4,756)	5,001
Net increase in cash and cash equivalents	819,525	155,062
Cash, cash equivalents and restricted cash—beginning of period	1,667,526	1,231,707
Cash, cash equivalents and restricted cash—end of period	2,487,051	1,386,769
Supplemental disclosure of cash flow information:
Cash paid for interest	50,017	51,990
Cash paid for income taxes	10,316	4,154
Capitalization of costs related to construction financing lease obligation	3,389	33,827
Issuances of common stock from employee benefit plans receivable	5,509	868
Accrued share repurchase liability	$ 4,000	$ 0