Stock-based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	$ 3,020,000	$ 3,744,000	$ 5,226,000
Treasury Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		(12,000)	(1,042)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	(216,395)	(222,176)	(299,964)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	0	0	0
Performance Share Award Program [Member] | Performance Share Award Program 2011 Grant [Member] | Restricted Stock Units (RSUs) [Member] | Employee stock award program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock comp shares surrendered	29,593
Stock comp shares surrendered, value	3,600,000
Stock comp shares surrendered, per share price	$ 120.34
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	$ 100,000