Significant Accounting Policies (Details 4)	9 Months Ended
	Sep. 30, 2011 Employee Stock Options Y	Sep. 30, 2010 Employee Stock Options Y
Employee Stock Options:
Weighted-average assumptions
Risk-free interest rate (as a percent)	2.30%	2.80%
Dividend yield (as a percent)	0.00%	0.00%
Volatility (as a percent)	52.40%	55.70%
Expected Life (in years/months)	5.3	5.2
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)	34.90%	47.80%
Expected Life (in years/months)	6	6
Board of Director Stock Options:
Weighted-average assumptions
Risk-free interest rate (as a percent)	2.90%	2.70%
Dividend yield (as a percent)	0.00%	0.00%
Volatility (as a percent)	52.80%	57.70%
Expected Life (in years/months)	7.8	7.8