CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income (loss)		$ 24,047	$ (18,359)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization of debt discounts		11,058	11,835
Stock-based compensation		20,769	17,558
Other, net		178
Unrealized loss on long term investment		2,950
Excess tax benefit from stock based compensation			(3,833)
Changes in operating assets and liabilities:
Accounts receivable		13,170	(11,671)
Prepaid expenses and other assets		(3,667)	(194)
Inventory		752	1
Accounts payable		1,814	2,124
Accrued and other liabilities		29,679	1,190
Deferred revenue - collaborative agreements		(3,215)	(3,237)
Net cash provided by (used in) operating activities		97,535	(4,586)
Cash flows from investing activities:
Long term investment			(39,829)
Capital expenditures		(5,562)	(3,553)
Purchases of marketable securities		(16,795)	(34,467)
Sale and maturities of marketable securities		51,114	19,274
Net cash provided by (used in) investing activities		28,757	(58,575)
Cash flows from financing activities:
Restricted investments, net		110	125
Proceeds from issuance of common stock under stock plans		10,219	29,180
Direct financing arrangement repayments		(445)	(452)
Excess tax benefit from stock based compensation			3,833
Net cash provided by financing activities		9,884	32,686
Net increase in cash and cash equivalents		136,176	(30,475)
Cash and cash equivalents at beginning of period	[1]	521,439
Cash and cash equivalents at end of period		657,615	421,822
Supplemental Schedule of Cash Flow Information
Interest paid		846	839
Incomes taxes paid		14	$ 13
Reclassification to common stock and additional paid in capital in connection with conversions of 1.25% convertible senior notes due 2020		$ 4

[1] The condensed consolidated balance sheet at December 31, 2015 has been derived from the audited financial statements at that date.