Condensed Consolidated Statements of Comprehensive Income (Unaudited) Statement - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 23,183	$ 22,451	$ 19,298	$ 109,254
Other comprehensive loss
Adoption of new accounting standards	0	0	0	408
Market value adjustments on interest rate swaps, net of tax	(8,121)	2,532	(41,415)	10,770
Reclassification adjustment for gain on terminated interest rate swap included in net income	0	0	(67)	0
Foreign currency translation adjustments	(13,529)	(6,129)	(9,007)	(23,729)
Supplemental benefit plans adjustments, net of tax	(149)	(124)	(448)	(371)
Total other comprehensive loss	(21,799)	(3,721)	(50,937)	(12,922)
Comprehensive income/(loss)	$ 1,384	$ 18,730	$ (31,639)	$ 96,332