Stockholders' Equity (Details 3)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Estimated fair value of purchase rights under the Employee stock purchase plan using Black-Scholes valuation model
Expected term (in years)	5 years	5 years 1 month 6 days	5 years 1 month 6 days	5 years 3 months 18 days
Expected volatility	46.00%	45.00%	46.00%	51.00%
Risk-free interest rate	0.67%	0.90%	0.78%	1.65%
Expected dividend yield
Employee Stock Purchase Plan [Member]
Estimated fair value of purchase rights under the Employee stock purchase plan using Black-Scholes valuation model
Expected term (in years)	6 months	6 months	6 months	4 months 21 days
Expected volatility	45.00%	45.00%	45.00%	36.00%
Risk-free interest rate	0.14%	0.07%	0.14%	0.18%
Expected dividend yield