Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 103,406	$ 46,270	$ 124,201	$ 26,683
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments	12,761	(60,015)	5,525	(39,468)
Interest rate swaps – net change in deferred gain or loss	(24,715)	3,093	(39,220)	13,207
Pension plans – net change in deferred actuarial loss	41	55	83	111
Other comprehensive (loss) income, net of tax	(11,913)	(56,867)	(33,612)	(26,150)
Comprehensive income (loss)	$ 91,493	$ (10,597)	$ 90,589	$ 533