Summary of Significant Accounting Policies (Details 8) (USD $)	1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 31, 2010 Life Sciences Tax Incentive Program 2010 item	Dec. 31, 2012 Life Sciences Tax Incentive Program 2010	Dec. 31, 2011 Life Sciences Tax Incentive Program 2010	Dec. 31, 2010 Life Sciences Tax Incentive Program 2010	Jan. 31, 2011 Life Sciences Tax Incentive Program 2011 item	Dec. 31, 2012 Life Sciences Tax Incentive Program 2011	Oct. 31, 2010 Federal Qualifying Therapeutic Discovery Projects program	Mar. 31, 2011 Federal Qualifying Therapeutic Discovery Projects program	Dec. 31, 2010 Federal Qualifying Therapeutic Discovery Projects program
Summary of significant accounting policies
Tax incentive awarded					$ 1,500,000				$ 1,347,000
State research and development tax credits monetized					1,350,000				1,212,000
Number of incremental employees pledged to be hired					50				50
Performance period					5 years				5 years
Amount of benefit recognized						270,000	270,000	270,000		484,000
Grants awarded											2,445,000
Grants received												504,000	1,941,000
Other income		(1,357,000)	(1,150,000)	(2,669,000)									(2,445,000)
Other Income (Expense)
Settlement from former service provider			1,800,000
Deferred Financing Costs
Deferred financing costs		32,000	1,946,000
Deferred financing costs netted against the equity proceeds within stockholders' equity	$ 2,748,000	$ 2,748,000		$ 25,000