Equity Incentive Program (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant under 2012 Plan	17,000,000		17,000,000
Stock-based compensation expense [Abstract]
Pre-tax compensation expense	$ 7,483	$ 6,018	$ 23,589	$ 20,025
Tax benefit	(2,643)	(2,107)	(8,330)	(7,009)
Total stock-based compensation expense, net of tax	$ 4,840	$ 3,911	$ 15,259	$ 13,016
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued during period (in shares)			1,719,943	1,524,329
Risk-free interest rate (in hundredths)			1.05%	2.68%
Dividend yield (in hundredths)			2.03%	1.70%
Expected life (in years)			5 years 8 months	5 years 10 months
Volatility (in hundredths)			36.41%	33.56%
Grant price (in dollars per share)			$ 65.38	$ 66.59
Fair value at date of grant (in dollars per share)			$ 18.51	$ 20.13
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued during period (in shares)			50,416	44,751
Risk-free interest rate (in hundredths)			0.37%	1.34%
Dividend yield (in hundredths)			2.03%	1.61%
Expected life (in years)			2 years 11 months	2 years 11 months
Volatility (in hundredths)			34.10%	40.48%
Fair value at date of grant (in dollars per share)			$ 71.98	$ 91.41