Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating activities:
Net loss	$ (46,743)	$ (60,199)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	4,538	3,502
Depreciation and amortization	1,172	1,192
Amortization of debt issuance costs and non-cash interest	1,898	1,289
Change in fair value of warrant liabilities	3,611	(546)
Change in fair value of embedded derivatives	(166)	(137)
Changes in operating assets and liabilities:
Trade accounts receivable	(591)	(1,473)
Inventory, net	2,546	1,089
Prepaid expenses and other current assets	(469)	(181)
Other assets	(286)	213
Accounts payable and accrued expenses	(805)	(529)
Deferred rent	49	(44)
Deferred revenue	(8,462)	(8,411)
Net cash used in operating activities	(43,708)	(64,235)
Investing activities:
Purchases of property and equipment	(255)	(426)
Net cash used in investing activities	(255)	(426)
Financing activities:
Proceeds from revolving credit facility	9,900	34,353
Payments on borrowings of debt	(40,051)	(6,094)
Proceeds from exercise of common stock options	27	92
Proceeds from issuance of common stock and common stock warrants	67,114	57,985
Net cash provided by financing activities	36,990	86,336
Net (decrease) increase in cash and cash equivalents	(6,973)	21,675
Cash and cash equivalents at beginning of period	56,525	49,172
Cash and cash equivalents at end of period	$ 49,552	$ 70,847