Pension Plans and Other Postretirement Benefits - Domestic and Foreign Pension and Postretirement Defined Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Total net pension and postretirement benefits cost (credit)	$ 577	$ (890)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,130	1,268
Interest cost	8,320	8,027
Expected return on assets	(9,452)	(10,764)
Amortization of prior service benefit	6	22
Total net pension and postretirement benefits cost (credit)	4	(1,447)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	24	29
Interest cost	549	542
Expected return on assets	0	(2)
Amortization of prior service benefit	0	(12)
Total net pension and postretirement benefits cost (credit)	$ 573	$ 557