Pension Plans and Other Postretirement Benefits - Domestic and Foreign Pension and Postretirement Defined Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Total net pension benefits (credit) cost	$ 74	$ 846	$ 67	$ 3,056
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,067	842	3,090	3,123
Interest cost	8,375	9,115	24,983	27,978
Expected return on assets	(9,960)	(9,920)	(29,799)	(30,429)
Actuarial gain	0	0	0	(50)
Amortization of prior service benefit	29	230	102	698
Total net pension benefits (credit) cost	(489)	267	(1,624)	1,320
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	30	29	91	86
Interest cost	585	620	1,755	1,862
Expected return on assets	(28)	(46)	(83)	(140)
Amortization of prior service benefit	(24)	(24)	(72)	(72)
Total net pension benefits (credit) cost	$ 563	$ 579	$ 1,691	$ 1,736