CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Balances, value at Dec. 31, 2009	$ 22,657	$ 33	$ 230,441	$ (24)	$ (207,793)
Balances, shares at Dec. 31, 2009		33,563,670
Issuance of common stock pursuant to stock plans, value	140	1	139
Issuance of common stock pursuant to stock plans, shares		138,572
Stock-based compensation	803		803
Change in unrealized gain (loss) on marketable securities	25			25
Net loss	(18,682)				(18,682)
Balances, value at Dec. 31, 2010	4,943	34	231,383	1	(226,475)
Balances, shares at Dec. 31, 2010		33,702,242
Issuance of common stock to certain investors, net of issuance costs of $0.4 million & $2.5 million for 2012 & 2011 respectively	24,007	15	23,992
Issuance of common stock to certain investors, net of issuance costs, shares		15,284,118
Issuance of common stock pursuant to stock plans, value	149		149
Issuance of common stock pursuant to stock plans, shares		142,115
Stock-based compensation	1,039		1,039
Change in unrealized gain (loss) on marketable securities	(2)			(2)
Net loss	(25,653)				(25,653)
Balances, value at Dec. 31, 2011	4,483	49	256,563	(1)	(252,128)
Balances, shares at Dec. 31, 2011	49,128,475	49,128,475
Issuance of common stock to certain investors, net of issuance costs of $0.4 million & $2.5 million for 2012 & 2011 respectively	12,323	2	12,321
Issuance of common stock to certain investors, net of issuance costs, shares		2,022,144
Exercise of warrants to purchase common stock		4,727,331
Exercise of warrants to purchase common stock, value	8,849	5	8,844
Issuance of common stock pursuant to stock plans, value	738		738
Issuance of common stock pursuant to stock plans, shares		553,257
Stock-based compensation	3,010		3,010
Reclassification of fair value of warrants exercised from liability to equity	27,867		27,867
Change in unrealized gain (loss) on marketable securities	12			12
Net loss	(71,135)				(71,135)
Balances, value at Dec. 31, 2012	$ (13,853)	$ 56	$ 309,343	$ 11	$ (323,263)
Balances, shares at Dec. 31, 2012	56,431,207	56,431,207