CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 1,198,511	$ 895,522	$ 636,056
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	145,467	104,745	74,909
Non-cash compensation expense	507,277	559,878	459,049
Other non-cash charges and expenses, net	63,581	45,139	52,562
Deferred Taxes	318,809	(360,078)	(121,623)
Changes in assets and liabilites
Increase in Sanofi, Bayer, and trade accounts receivable	(362,720)	(143,827)	(491,421)
Increase in Inventories	(314,195)	(149,776)	(111,825)
(Increase) decrease in prepaid expenses and other assets	(113,331)	23,543	(79,476)
(Decrease) increase in deferred revenue	(113,099)	244,270	608,892
(Decrease) increase in accounts payable, accrued expenses and other liabilities	(23,188)	253,980	303,657
Total adjustments	108,601	577,874	694,724
Net cash provided by operating activities	1,307,112	1,473,396	1,330,780
Cash flows from investing activities:
Purchases of marketable and other securities	(1,277,140)	(809,419)	(557,105)
Sales or maturities of marketable securities	544,584	274,456	327,437
Capital expenditures	(272,626)	(511,941)	(677,933)
Net cash used in investing activities	(1,005,182)	(1,046,904)	(907,601)
Cash flows from financing activities:
Proceeds in connection with capital and facility lease obligations	57,000	5,085	27,373
Payments in connection with capital and facility lease obligations	(19,925)	(32,774)	(1,353)
Repayments of convertible senior notes	0	(12,894)	(166,467)
Payments in connection with reduction of outstanding warrants	0	(643,365)	(573,487)
Proceeds from issuance of Common Stock	240,213	126,739	206,358
Payments in connection with Common Stock tendered for employee tax obligations	(301,688)	(143,182)	(160,537)
Excess Tax Benefit from Share-based compensation	0	0	405,317
Net cash used in financing activities	(24,400)	(700,391)	(262,796)
Net increase (decrease) in cash and cash equivalents	277,530	(273,899)	160,383
Cash and cash equivalents at beginning of period	535,203	809,102	648,719
Cash and cash equivalents at end of period	812,733	535,203	809,102
Cash paid for interest (net of amounts capitalized)	18,678	5,454	10,582
Cash paid for income taxes	$ 754,843	$ 481,360	276,092
Warrant
Cash flows from financing activities:
Payments in connection with reduction of outstanding warrants			$ (399,500)