Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 266,745	$ 233,290	$ 122,456
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments	10,375	4,169	(31,245)
Interest rate swaps - net change in deferred gain or loss	(30,940)	(39,394)	(10,844)
Pension plans - net change in deferred actuarial gain or loss	(725)	(2,846)	123
Other comprehensive (loss) income, net of tax	(21,290)	(38,071)	(41,966)
Comprehensive income	$ 245,455	$ 195,219	$ 80,490