Stock-Based Compensation (Details)	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended					6 Months Ended	1 Months Ended	6 Months Ended		1 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Minimum	Jun. 30, 2011 Minimum	Jun. 30, 2012 Minimum	Jun. 30, 2011 Minimum	Jun. 30, 2012 Maximum	Jun. 30, 2011 Maximum	Jun. 30, 2012 Maximum	Jun. 30, 2011 Maximum	Jun. 30, 2012 Employee	Jun. 30, 2011 Employee	Dec. 31, 2011 2008 Plan	Jun. 30, 2012 2008 Plan Employee	Apr. 30, 2012 2011 Plan	Jun. 30, 2012 2011 Plan Employee	Jun. 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)			294,000										300,000	1,900,000					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)		2.50%		2.50%	0.89%		0.89%		1.11%		1.11%
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%	0.00%
Expected term					5 years 9 months 18 days	5 years	5 years 9 months 18 days	5 years	5 years 10 months 24 days	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%	71.00%		71.00%		72.00%		72.00%