Stock-Based Compensation (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Assumptions used in the Black-Scholes option-pricing model
Risk free interest rate , minimum	0.70%	1.80%	0.20%	1.80%
Risk free interest rate, maximum	1.00%	2.60%	1.20%	2.60%
Expected volatility, minimum	81.50%	72.30%	80.60%	72.30%
Expected volatility, maximum	82.80%	75.20%	82.80%	89.70%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Maximum [Member]
Assumptions used in the Black-Scholes option-pricing model
Expected term	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days
Minimum [Member]
Assumptions used in the Black-Scholes option-pricing model
Expected term	5 years	5 years 1 month 6 days	5 years	5 years