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	$ (57,334)	$ (46,044)
Adjustments to reconcile net loss to net cash used in operating activities
Non-cash interest expense	4,038	4,267
Depreciation and amortization	2,092	2,241
Stock-based compensation	8,337	7,091
Changes in operating assets and liabilities
Purchased premiums and interest on available-for-sale securities		(4)
Accounts receivable	1,711	(748)
Accounts payable, accrued expenses and other	7,474	(6,027)
Deferred revenues	(26,502)	(26,169)
Other assets and liabilities, net	527	1,173
Net cash used in operating activities	(59,657)	(64,220)
Cash flows from investing activities
Purchases of available-for-sale securities		(20,100)
Proceeds from maturities of available-for-sale securities	53,963	94,733
Purchases of property and equipment	(4,105)	(2,983)
Net cash provided by investing activities	49,858	71,650
Cash flows from financing activities
Proceeds from exercise of common stock options and warrants	6,542	4,936
Proceeds from issuance of preferred stock of Silver Creek Pharmaceuticals, Inc.	1,233
Proceeds from convertible notes issued by Silver Creek Pharmaceuticals, Inc., net of issuance costs		300
Other financing activities, net		(1)
Net cash provided by financing activities	7,775	5,235
Net (decrease) increase in cash and cash equivalents	(2,024)	12,665
Cash and cash equivalents, beginning of period	35,688	65,086
Cash and cash equivalents, end of period	33,664	77,751
Non-cash investing and financing activities
Disposal of fully depreciated assets	106	670
Property and equipment in accounts payable and accrued expenses	2,060	564
Receivables related to stock option exercises	160
Supplemental disclosure of cash flows
Cash paid for interest	$ 4,946	$ 4,915