Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities
Net loss	$ (46,044)	$ (58,574)
Adjustments to reconcile net loss to net cash used in operating activities
Non-cash interest expense	4,267	470
Depreciation and amortization	2,241	1,319
Stock-based compensation	7,091	5,416
Changes in operating assets and liabilities
Purchased premiums and interest on available-for-sale securities	(4)	(291)
Accounts receivable	(748)	(5,270)
Accounts payable, accrued expenses and other	(6,027)	11,386
Deferred revenues	(26,169)	(2,404)
Other assets and liabilities, net	1,173	2,518
Net cash used in operating activities	(64,220)	(45,430)
Cash flows from investing activities
Purchases of available-for-sale securities	(20,100)	(8,290)
Proceeds from maturities of available-for-sale securities	94,733	49,010
Purchases of property and equipment	(2,983)	(3,305)
Other investing activities, net		(39)
Net cash provided by investing activities	71,650	37,376
Cash flows from financing activities
Proceeds from exercise of common stock options and warrants	4,936	1,204
Proceeds from convertible notes issued by majority owned subsidiary, net of issuance costs	300	274
Other financing activities, net	(1)	(195)
Net cash provided by financing activities	5,235	1,283
Net increase (decrease) in cash and cash equivalents	12,665	(6,771)
Cash and cash equivalents, beginning of period	65,086	37,714
Cash and cash equivalents, end of period	77,751	30,943
Non-cash investing and financing activities
Issuance of derivative liability	37	35
Property and equipment in accounts payable and accrued expenses	564
Disposal of fully depreciated assets	670	77
Supplemental disclosure of cash flows
Cash paid for interest	$ 4,915	$ 2,076