CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net loss	$ 6,531	$ (48,481)	$ (83,147)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization of debt discounts	44,883	41,413	29,207
Stock-based compensation	69,872	62,156	38,398
Debt exchange expense on senior note conversions		265	11,484
Other, net	(1,612)
Unrealized loss on long term investment	4,581
Loss on repurchase of convertible senior notes			17,934
Excess tax benefit from stock based compensation	(2,872)	22	(214)
Changes in operating assets and liabilities:
Accounts receivable	(56,517)	(22,559)	35,577
Prepaid expenses and other assets	3,583	(30,489)	247
Inventory	98	(4,093)	(6,590)
Accounts payable	5,623	5,360	5,141
Accrued and other liabilities	25,245	35,530	27,189
Deferred revenue - collaborative agreements	(12,879)	(12,868)	(66,046)
Net cash provided by (used in) operating activities	86,536	26,256	9,180
Cash flows from investing activities:
Long term investment	(39,829)
Capital expenditures	(26,003)	(27,876)	(4,267)
Purchases of marketable securities	(108,152)	(134,091)	(33,713)
Sale and maturities of marketable securities	68,974	23,528	583
Net cash used in investing activities	(105,010)	(138,439)	(37,397)
Cash flows from financing activities:
Restricted investments, net	7	500	(15,000)
Proceeds from issuance of common stock under stock plans	86,436	92,844	73,157
Direct financing arrangement repayments	(1,699)
Excess tax provision (benefit) from stock based compensation	2,872	(22)	214
Proceeds from issuance of convertible senior notes, net of costs			728,696
Repurchase of convertible senior notes			(499,994)
Cash paid in connection with exchange of 4.75% convertible senior notes due 2015		(265)	(11,484)
Net cash provided by financing activities	87,616	93,057	275,589
Foreign currency translation change		(6)
Net decrease in cash and cash equivalents	69,142	(19,132)	247,372
Cash and cash equivalents at beginning of period	452,297	471,429	224,057
Cash and cash equivalents at end of period	521,439	452,297	471,429
Supplemental Schedule of Cash Flow Information
Interest paid	12,746	11,290	15,587
Incomes taxes paid	62	37	140
Purchase of property and equipment financed by direct financing lease		31,495	19,274
Pfizer Notes Due 2014
Supplemental Schedule of Cash Flow Information
Reclassification to common stock and additional paid in capital in connection with conversion/exchange of debt instruments			9,373
4.75% Convertible Senior Notes due 2015
Adjustments to reconcile net loss to net cash used in operating activities:
Loss on repurchase of convertible senior notes			(17,900)
Cash flows from financing activities:
Repurchase of convertible senior notes		(300)	(11,500)
Supplemental Schedule of Cash Flow Information
Reclassification to common stock and additional paid in capital in connection with conversion/exchange of debt instruments	88,974	$ 5,161	154,338
Reclassification to additional paid in capital in connection with repurchase of debt instruments			$ (381,405)
1.25% Convertible Senior Notes due 2020
Supplemental Schedule of Cash Flow Information
Reclassification to common stock and additional paid in capital in connection with conversion/exchange of debt instruments	$ 180