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	$ 122,456	$ 3,279	$ 193,582
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments	(31,245)	47,363	(5,986)
Interest rate swaps - net change in deferred gain or loss	(10,844)	3,892	1,670
Pension plans - net change in deferred actuarial loss	123	(64)	(965)
Other comprehensive (loss) income, net of tax	(41,966)	51,191	(5,281)
Comprehensive income	$ 80,490	$ 54,470	$ 188,301