STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-in Capital Common Stock	Additional Paid-in Capital Warrants	Deficit Accumulated During the Development Stage
Beginning Balance at Dec. 31, 2009	$ 28,104	$ 42	$ 96,133	$ 23,073	$ (91,144)
Beginning Balance (in shares) at Dec. 31, 2009		41,583,528
Stock-based compensation	3,198		3,198
Exercise of employee stock options (in shares)		196,167
Exercise of employee stock options	225		225
Exercise of warrants to purchase common stock (in shares)		39,225
Exercise of warrants to purchase common stock	121		360	(239)
Issuance of restricted common stock (in shares)		115,000
Repurchase of shares of common stock (in shares)		(364,992)
Repurchase of shares of common stock	(1,429)		(1,429)
Forfeiture of unvested restricted common stock (in shares)		(11,250)
Issuance of common stock in a securities offering, net of commissions and expenses of $2,203 (in shares)		7,000,000
Issuance of common stock in a securities offering, net of commissions and expenses of $2,203	32,804	7	32,797
Net loss	(20,819)				(20,819)
Ending Balance at Sep. 30, 2010	$ 42,204	$ 49	$ 131,284	$ 22,834	$ (111,963)
Ending Balance (in shares) at Sep. 30, 2010		48,557,678