Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	$ 3,744
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)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	(183,455)	(216,395)	(222,176)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation		$ 0	$ 0
Performance Share Award Program [Member] | Performance Share Award Program 2013 Grant [Domain] | 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	25,162
Stock comp shares surrendered, value	$ 2,700
Stock comp shares surrendered, per share price	$ 108.74
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	$ 400