Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 175,635	$ 183,766	$ 182,801
Other comprehensive (loss) income, net of tax
Foreign currency translation adjustments	(23,089)	(27,461)	503
Interest rate hedges - net change in deferred loss	(1,339)	2,163	2,107
Pension plans - net change in deferred actuarial loss	1,196	(4,217)	(233)
Other comprehensive (loss) income, net of tax	(23,232)	(29,515)	2,377
Comprehensive income	$ 152,403	$ 154,251	$ 185,178