Non-pension Post-retirement Benefits (Net Benefit Costs) (Details) - Non-pension Post-retirement Benefit Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 605	$ 632
Interest cost on projected benefit obligation	1,860	2,148
Amortization of unrecognized:
Prior service cost (credit)	(282)	(201)
Actuarial gain	(273)	(316)
Non-pension post-retirement benefit expense (income)	1,910	2,263
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	604	631
Interest cost on projected benefit obligation	1,822	2,104
Amortization of unrecognized:
Prior service cost (credit)	(282)	(201)
Actuarial gain	(209)	(257)
Non-pension post-retirement benefit expense (income)	1,935	2,277
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Interest cost on projected benefit obligation	38	44
Amortization of unrecognized:
Prior service cost (credit)	0	0
Actuarial gain	(64)	(59)
Non-pension post-retirement benefit expense (income)	$ (25)	$ (14)