Equity Incentive Program (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 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	$ 7,532	$ 5,974	$ 16,106	$ 14,007
Tax benefit	(2,580)	(2,091)	(5,687)	(4,902)
Total stock-based compensation expense, net of tax	$ 4,952	$ 3,883	$ 10,419	$ 9,105
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 (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 (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