Stock-based Compensation Stock-based Compensation (Details 3)	3 Months Ended		6 Months Ended
	Jun. 30, 2012 Years	Jun. 30, 2011 Years	Jun. 30, 2012 Years	Jun. 30, 2011 Years
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.40%	1.00%	0.40%	1.00%
Expected dividend yield	1.30%	0.70%	1.30%	0.70%
Expected term	4.2	4.3	4.2	4.3
Expected volatility	39.70%	42.30%	39.70%	42.30%
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.20%	0.10%	0.20%	0.10%
Expected dividend yield	1.30%	0.70%	1.30%	0.70%
Expected term	6	6	6	6
Expected volatility	27.40%	21.30%	27.40%	21.30%