CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015		Jun. 30, 2014
Cash flows from operating activities:
Net loss	$ (9,063)		$ (70,830)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization of debt discounts	23,101		19,321
Stock-based compensation	35,150		30,825
Debt exchange expense on senior note conversions			265
Unrealized gain on long term investment	(27,174)
Excess tax provision (benefit) from stock based compensation	(2,073)		31
Changes in operating assets and liabilities:
Accounts receivable	(17,189)		(11,831)
Prepaid expenses and other assets	946		(10,494)
Inventory	(1,009)		(517)
Accounts payable	4,700		8,149
Accrued and other liabilities	7,866		(4,736)
Deferred revenue - collaborative agreements	(6,451)		(6,434)
Net cash provided by (used in) operating activities	8,804		(46,251)
Cash flows from investing activities:
Long term investment	(39,829)
Capital expenditures	(5,749)		(11,362)
Purchases of marketable securities	(80,212)		(65,115)
Maturities of marketable securities	40,524		247
Net cash used in investing activities	(85,266)		(76,230)
Cash flows from financing activities:
Restricted investments, net	(273)
Proceeds from issuance of common stock under stock plans	62,958		57,612
Direct financing arrangement repayments	(912)
Excess tax provision (benefit) from stock based compensation	2,073		(31)
Cash paid in connection with exchange of 4.75% convertible senior notes due 2015			(265)
Net cash provided by financing activities	63,846		57,316
Net decrease in cash and cash equivalents	(12,616)		(65,165)
Cash and cash equivalents at beginning of period	452,297	[1]	471,429
Cash and cash equivalents at end of period	439,681		406,264
Supplemental Schedule of Cash Flow Information
Interest paid	1,670		5,241
Incomes taxes paid	83
Convertible Senior Notes 4.75 Percent Due 2015
Supplemental Schedule of Cash Flow Information
Reclassification to additional paid in capital in connection with conversions or exchanges of 4.75% convertible senior notes due 2015	$ 45,327		$ 4,446

[1] The condensed consolidated balance sheet at December 31, 2014 has been derived from the audited financial statements at that date.