Nonpension Postretirement Benefits (Net Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Nonpension Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	$ 798	$ 856	$ 1,008
Interest cost on projected benefit obligation	2,659	2,589	2,948
Amortization of unrecognized:
Prior service cost	140	140	140
Loss (gain)	34	536	267
Nonpension postretirement benefit expense	3,631	4,121	4,363
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	797	855	1,007
Interest cost on projected benefit obligation	2,608	2,537	2,840
Amortization of unrecognized:
Prior service cost	140	140	140
Loss (gain)	81	592	267
Nonpension postretirement benefit expense	3,626	4,124	4,254
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost (benefits earned during the period)	1	1	1
Interest cost on projected benefit obligation	51	52	108
Amortization of unrecognized:
Prior service cost	0	0	0
Loss (gain)	(47)	(56)	0
Nonpension postretirement benefit expense	$ 5	$ (3)	$ 109