Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Operating activities:
Net loss	$ (10,292)	$ (18,983)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	1,256	951
Depreciation and amortization	393	391
Amortization of debt issuance costs and non-cash interest	681	342
Change in fair value of warrant liability	(49)	0
Change in fair value of embedded derivatives	(38)	0
Changes in operating assets and liabilities:
Trade accounts receivable	(30)	755
Inventory, net	1,995	41
Prepaid expenses and other current assets	(431)	110
Other assets	(197)	41
Accounts payable and accrued expenses	466	(3,097)
Deferred rent	(14)	(15)
Deferred revenue	(8,462)	(3,378)
Net cash used in operating activities	(14,722)	(22,842)
Investing activities:
Purchases of property and equipment	(111)	(119)
Net cash used in investing activities	(111)	(119)
Financing activities:
Proceeds from revolving credit facility	5,163	2,414
Payments on borrowings of debt	(7,013)	(2,379)
Proceeds from exercise of common stock options	2	14
Net cash provided by (used in) financing activities	(1,848)	49
Net decrease in cash and cash equivalents	(16,681)	(22,912)
Cash and cash equivalents at beginning of period	56,525	49,172
Cash and cash equivalents at end of period	$ 39,844	$ 26,260