Pension Plans and Other Postretirement Benefits Domestic and Foreign Pension and Postretirement Defined Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Total net pension benefits (credit) cost	$ 19	$ 1,412	$ (7)	$ 2,210
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,020	1,233	2,023	2,281
Interest cost	8,320	9,498	16,608	18,863
Expected return on assets	(9,931)	(10,337)	(19,839)	(20,509)
Actuarial gain	0	0	0	(50)
Amortization of prior service benefit	46	440	73	468
Total net pension benefits (credit) cost	(545)	834	(1,135)	1,053
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	30	28	61	57
Interest cost	585	621	1,170	1,242
Expected return on assets	(27)	(47)	(55)	(94)
Amortization of prior service benefit	(24)	(24)	(48)	(48)
Total net pension benefits (credit) cost	$ 564	$ 578	$ 1,128	$ 1,157