Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 41,388	$ 11,753	$ 165,589	$ 38,436
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments	3,553	964	9,078	(38,504)
Interest rate swaps – net change in deferred gain or loss	(11,379)		(50,599)
Interest rate swaps – net change in deferred gain or loss		350		13,557
Pension plans – net change in deferred actuarial loss	41	53	124	164
Other comprehensive (loss) income, net of tax	(7,785)	1,367	(41,397)	(24,783)
Comprehensive income	$ 33,603	$ 13,120	$ 124,192	$ 13,653