Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities
Net loss	$ (18,414)	$ (9,277)
Adjustments to reconcile loss to net cash used in operating activities:
Change in fair value of warrant liability	(79)	328
Unrealized (loss) gain on marketable securities	(32)	8
Depreciation and amortization	162	225
Amortization of deferred financing costs and debt discount	83	83
Stock-based compensation expense	337	52
Changes in operating assets and liabilities :
Accounts receivable	(1,650)
Interest receivable	(8)
Inventory	(1,961)
Prepaid expenses and other assets	133	(158)
Accounts payable and accrued expenses	238	(1,254)
Deferred product revenue, net	3,551
Deferred licensing revenue	373	(58)
Other non-current liabilities	44	(17)
Net cash used in operating activities	(17,223)	(10,068)
Cash flows from investing activities
Purchases of marketable securities	(15,643)	(21,806)
Sales and maturities of marketable securities	12,866	293
Purchases of property and equipment, net	(372)	(40)
Net cash used in investing activities	(3,149)	(21,553)
Cash flows from financing activities
Proceeds from issuance of common stock	1,936	49
Repayment of secured notes payable	(2,832)	(437)
Financing costs and underwriters discounts	(125)	(669)
Net cash used in financing activities	(1,021)	(1,057)
Net change in cash and cash equivalents	(21,393)	(32,678)
Cash and cash equivalents at beginning of period	40,302	48,544
Cash and cash equivalents at end of period	18,909	15,866
Supplemental cash flow information:
Cash paid for interest	$ 610	$ 688