Retirement Plans and Postretirement Medical Benefits (Estimated Amounts to be Amortized from AOCI into Net Periodic Benefit) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
United States
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 29,071
Prior service credit	(60)
Transition asset	0
Total	29,011
Foreign
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	8,279
Prior service credit	(77)
Transition asset	(8)
Total	8,194
Nonpension postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	297
Prior service credit	3,537
Total	$ 3,834