Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 30,484	$ 30,366	$ 127,097	$ 109,872
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(3,032)	(7,900)	2,371	(21,783)
Interest rate hedges – net change in deferred loss	3,214	(5,810)	(5,865)	(6,480)
Pension – net change in actuarial deferred loss	37	53	112	159
Other comprehensive income (loss), net of tax	219	(13,657)	(3,382)	(28,104)
Comprehensive income	$ 30,703	$ 16,709	$ 123,715	$ 81,768