Pension (Contributions to Pension Plans) (Details) - Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Estimated contributions in 2018	$ 2,279
Employer contributions	3,150	$ 3,535
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Estimated contributions in 2018	131
Employer contributions	499	259
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Estimated contributions in 2018	2,148
Employer contributions	$ 2,651	$ 3,276