Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 193,582	$ 175,635	$ 183,766
Other comprehensive (loss) income, net of tax
Foreign currency translation adjustments	(5,986)	(23,089)	(27,461)
Interest rate hedges - net change in deferred loss	1,670	(1,339)	2,163
Pension plans - net change in deferred actuarial loss	(965)	1,196	(4,217)
Other comprehensive (loss) income, net of tax	(5,281)	(23,232)	(29,515)
Comprehensive income	$ 188,301	$ 152,403	$ 154,251