Consolidated Statements Of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]	Total
Balance at Dec. 31, 2008	$ 9,496	$ 33	$ 410,444	$ 212	$ (385,907)	$ 34,278
Balance, shares at Dec. 31, 2008	3	32,544
Components of comprehensive loss:
Net loss	0	0	0	0	(24,135)	(24,135)
Net change in unrealized gain (loss) on investments	0	0	0	(154)	0	(154)
Comprehensive loss						(24,289)
Issuance of common stock from public offering, net of expenses	0	6	9,329	0	0	9,335
Issuance of common stock from public offering, net of expenses, shares		6,000
Issuance of common stock from exercise of stock options and purchases from ESPP	0	0	78	0	0	78
Issuance of common stock from exercise of stock options and purchases from ESPP, shares		134
Stock-based compensation	0	0	2,046	0	0	2,046
Balance at Dec. 31, 2009	9,496	39	421,897	58	(410,042)	21,448
Balance, shares at Dec. 31, 2009	3	38,678
Components of comprehensive loss:
Net loss	0	0	0	0	(16,911)	(16,911)
Net change in unrealized gain (loss) on investments	0	0	0	50	0	50
Comprehensive loss						(16,861)
Issuance of common stock from public offering, net of expenses	0	8	16,940	0	0	16,948
Issuance of common stock from public offering, net of expenses, shares		8,306
Issuance of common stock from exercise of stock options and purchases from ESPP	0	0	369	0	0	369
Issuance of common stock from exercise of stock options and purchases from ESPP, shares		345
Stock-based compensation	0	0	1,828	0	0	1,828
Balance at Dec. 31, 2010	9,496	47	441,034	108	(426,953)	23,732
Balance, shares at Dec. 31, 2010	3	47,329
Components of comprehensive loss:
Net loss	0	0	0	0	(16,982)	(16,982)
Net change in unrealized gain (loss) on investments	0	0	0	(108)	0	(108)
Comprehensive loss						(17,090)
Issuance of common stock from public offering, net of expenses	0	4	9,674	0	0	9,678
Issuance of common stock from public offering, net of expenses, shares		3,701
Issuance of common stock from exercise of stock options and purchases from ESPP	0	0	143	0	0	143
Issuance of common stock from exercise of stock options and purchases from ESPP, shares		181
Stock-based compensation	0	0	1,850	0	0	1,850
Balance at Dec. 31, 2011	$ 9,496	$ 51	$ 452,701	$ 0	$ (443,935)	$ 18,313
Balance, shares at Dec. 31, 2011	3	51,211