Consolidated Statements Of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock [Member] Underwritten Public Offering [Member]	Common Stock [Member] License Agreements [Member]	Common Stock [Member]	Additional Paid-In Capital [Member] Underwritten Public Offering [Member]	Additional Paid-In Capital [Member] License Agreements [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income/ (Loss) [Member]	Underwritten Public Offering [Member]	License Agreements [Member]	Total
Balances at Dec. 31, 2008			$ 410			$ 228,764	$ (174,054)	$ 276			$ 55,396
Balances, shares at Dec. 31, 2008			41,057,077
Issuance of common stock	30	6		20,830	4,911				20,860	4,917
Issuance of common stock, shares	3,000,000	636,133
Issuance of common stock upon exercise of stock options and in connection with restricted stock units			2			486					488
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, shares			160,159
Issuance of common stock under employee stock purchase plan			2			497					499
Issuance of common stock under employee stock purchase plan, shares			141,040
Stock-based compensation						8,467					8,467
Comprehensive loss:
Net unrealized gain (loss) on marketable securities								(258)			(258)
Net loss							(18,587)				(18,587)
Comprehensive loss											(18,845)
Balances at Dec. 31, 2009			450			263,955	(192,641)	18			71,782
Balances, shares at Dec. 31, 2009			44,994,409
Issuance of common stock upon exercise of stock options and in connection with restricted stock units			2			736					738
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, shares			249,156
Issuance of common stock under employee stock purchase plan			2			445					447
Issuance of common stock under employee stock purchase plan, shares			134,174
Stock-based compensation						7,818					7,818
Comprehensive loss:
Net unrealized gain (loss) on marketable securities								(24)			(24)
Net loss							(24,854)				(24,854)
Comprehensive loss											(24,878)
Balances at Dec. 31, 2010			454			272,954	(217,495)	(6)			55,907
Balances, shares at Dec. 31, 2010			45,377,739
Issuance of common stock	67			50,152					50,219
Issuance of common stock, shares	6,700,000
Issuance of common stock upon exercise of stock options and in connection with restricted stock units			3			1,191					1,194
Issuance of common stock upon exercise of stock options and in connection with restricted stock units, shares			324,416
Issuance of common stock under employee stock purchase plan			2			461					463
Issuance of common stock under employee stock purchase plan, shares			152,640
Stock-based compensation						8,081					8,081
Comprehensive loss:
Net unrealized gain (loss) on marketable securities								18			18
Net loss							(35,750)				(35,750)
Comprehensive loss											(35,732)
Balances at Dec. 31, 2011			$ 526			$ 332,839	$ (253,245)	$ 12			$ 80,132
Balances, shares at Dec. 31, 2011			52,554,795