Equity Incentive Program (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant under 2012 Plan	17,000,000
Stock-based compensation expense [Abstract]
Pre-tax compensation expense	$ 8,348	$ 8,574
Tax benefit	(2,975)	(3,107)
Total stock-based compensation expense, net of tax	$ 5,373	$ 5,467
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued during period (in shares)	1,602,195	1,719,943
Risk-free interest rate (in hundredths)	1.39%	1.05%
Dividend yield (in hundredths)	2.06%	2.03%
Expected life (in years)	7 years 1 month	5 years 8 months
Volatility (in hundredths)	33.78%	36.41%
Grant price (in dollars per share)	$ 71.86	$ 65.38
Fair value at date of grant (in dollars per share)	$ 20.62	$ 18.51
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued during period (in shares)	47,032	50,416
Risk-free interest rate (in hundredths)	0.40%	0.37%
Dividend yield (in hundredths)	2.06%	2.03%
Expected life (in years)	2 years 11 months	2 years 11 months
Volatility (in hundredths)	30.36%	34.10%
Fair value at date of grant (in dollars per share)	$ 80.47	$ 71.98