Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 83,019	$ 32,585	$ 52,812
Other comprehensive income/(loss), before tax:
Foreign currency translation adjustments	(27,383)	44,162	(23,967)
Pension/postretirement settlements and curtailments	1,494		51
Pension/postretirement plan remeasurement	851	2,955	(5,498)
Amortization of pension liability adjustments:
Prior service credit	(4,454)	(4,453)	(4,450)
Net actuarial loss	5,175	5,439	5,102
Payments related to interest rate swaps included in earnings	(146)	1,490	2,400
Derivative valuation adjustment	3,832	325	1,297
Income taxes related to items of other comprehensive income/(loss):
Pension/postretirement settlements and curtailments	(348)		(6)
Pension/postretirement plan remeasurement	(408)	(918)	1,104
Amortization of pension liability adjustments	(158)	(22)	27
Payments related to interest rate swaps included in earnings	37	(566)	(912)
Derivative valuation adjustment	(979)	(124)	(493)
Comprehensive income	60,532	80,873	27,467
Comprehensive income/(loss) attributable to the noncontrolling interest	111	(520)	77
Comprehensive income attributable to the Company	$ 60,421	$ 81,393	$ 27,390