Summary of Business and Significant Accounting Policies (Details 1)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Stock Options [Member]
Fair value of stock option grant and stock purchase right granted under the ESPP estimated on the date of grant using Black-Scholes option pricing model
Expected volatility, minimum		57.00%	54.00%	50.00%
Expected volatility, maximum	54.00%	69.00%	57.00%	69.00%
Expected term (in years)	6 years 18 days	5 years 7 months 28 days	6 years 18 days	5 years 9 months 29 days
Risk-free interest rate, minimum	0.87%	0.00%	0.87%	0.00%
Risk-free interest rate, maximum	0.93%	3.03%	1.18%	3.03%
Dividend yield
2012 ESPP [Member]
Fair value of stock option grant and stock purchase right granted under the ESPP estimated on the date of grant using Black-Scholes option pricing model
Expected volatility	0.42%		0.42%
Expected term (in years)	6 months 29 days		6 months 29 days
Risk-free interest rate	0.16%		0.16%
Dividend yield