Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (19,587)	$ 36,433
Other comprehensive income, net of tax:
Foreign currency translation adjustments	20,547	4,371
Interest rate swaps – net change in deferred gain or loss	10,114	(2,568)
Pension plans – net change in deferred actuarial loss	56	48
Other comprehensive income, net of tax	30,717	1,851
Comprehensive income	$ 11,130	$ 38,284