Significant Accounting Policies (Details 4)	6 Months Ended
	Jun. 30, 2011 Employee Stock Options	Jun. 30, 2010 Employee Stock Options
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)	51.40%	55.70%
Expected Life (in years/months)	5.3	5.1
ESPP:
Weighted-average assumptions
Risk-free interest rate (as a percent)	0.20%	0.20%
Dividend yield (as a percent)	0.00%	0.00%
Volatility (as a percent)	26.50%	54.80%
Expected Life (in years/months)	6	6