Pensions and Other Postretirement Benefits (Accrued Pension and Other Postretirement Costs) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Accrued pension and other postretirement costs	$ (14,713)	$ (11,597)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Accrued pension and other postretirement costs	(10,634)	(8,226)
OPEB Plans
Defined Benefit Plan Disclosure [Line Items]
Accrued pension and other postretirement costs	$ (3,833)	$ (3,373)