Stock-Based Compensation (Details)	3 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended					9 Months Ended	1 Months Ended	9 Months Ended			1 Months Ended
	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Minimum	Sep. 30, 2012 Minimum	Sep. 30, 2011 Minimum	Sep. 30, 2012 Maximum	Sep. 30, 2012 Maximum	Sep. 30, 2011 Maximum	Sep. 30, 2012 Employee	Sep. 30, 2011 Employee	Dec. 31, 2011 2008 Plan	Sep. 30, 2012 2008 Plan Employee	Apr. 30, 2012 2011 Plan	Sep. 30, 2012 2011 Plan Employee	Sep. 30, 2012 2011 Plan Non-employee	Sep. 30, 2011 2011 Plan Non-employee	Apr. 30, 2012 2011 Plan Director
Stock-based compensation
Common stock available for issuance (in shares)												830,000
Additional common stock available for issuance (in shares)														3,500,000
Stock options issued (in shares)		3,220,000								3,200,000	1,900,000					100,000	100,000
Vesting period													3 years		3 years			1 year
Assumptions used to estimate grant date fair value of options granted
Risk-free interest rate (as a percent)	1.60%			0.70%	0.90%	1.60%	0.90%	1.10%	2.50%
Expected term	5 years 10 months 24 days			5 years 3 months 18 days	5 years 3 months 18 days	5 years	5 years 10 months 24 days	5 years 10 months 24 days	5 years 10 months 24 days
Expected volatility (as a percent)	73.00%		73.00%	66.00%	66.00%		68.00%	72.00%