Significant Accounting Policies (Details 5) (USD $)	6 Months Ended
	Jun. 30, 2012 Y	Jun. 30, 2011 Y
Employee Stock Options:
Weighted-average assumptions
Risk-free interest rate (as a percent)	0.80%	2.30%
Dividend yield (as a percent)	0.00%	0.00%
Volatility (as a percent)	51.10%	51.40%
Expected Life (in years/months)	5.1	5.3
ESPP:
Weighted-average assumptions
Risk-free interest rate (as a percent)	0.10%	0.20%
Dividend yield (as a percent)	0.00%	0.00%
Volatility (as a percent)	42.30%	26.50%
Expected Life (in years/months)	6	6
RSUs
Weighted-average assumptions
Weighted-average grant date fair value (in dollars per unit)	7.60