CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 10,482	$ 10,974
Other comprehensive income/(loss), before tax:
Foreign currency translation adjustments	17,505	9,938
Amortization of pension liability adjustments:
Prior service credit	(1,114)	(1,113)
Net actuarial loss	1,297	1,347
Payments related to interest rate swaps included in earnings	180	600
Derivative valuation adjustment	5,715	416
Income taxes related to items of other comprehensive income/(loss):
Amortization of pension liability adjustment	(55)	(70)
Payments related to interest rate swaps included in earnings	(43)	(228)
Derivative valuation adjustment	(1,372)	(158)
Comprehensive income	32,595	21,706
Comprehensive income attributable to the noncontrolling interest	230	140
Comprehensive income attributable to the Company	$ 32,365	$ 21,566