Condensed Consolidated Statements of Comprehensive Income (Unaudited) Statement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other comprehensive income/(loss)
Adoption of new accounting standards	$ 0	$ 0	$ 408	$ 0
Market value adjustments on interest rate swaps, net of tax	4,101	50	8,238	1,580
Foreign currency translation adjustments	(13,486)	3,135	(17,600)	16,683
Supplemental benefit plans adjustments, net of tax	(123)	1,731	(247)	1,625
Total other comprehensive (loss)/income	(9,508)	4,916	(9,201)	19,888
Net income	58,516	41,260	86,803	56,698
Comprehensive income	$ 49,008	$ 46,176	$ 77,602	$ 76,586