Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income/(loss)	$ 59,005	$ (5,572)	$ 92,824	$ (3,885)
Other comprehensive income/(loss)
Market value adjustments on interest rate swaps, net of tax	(1,490)	(21,088)	(38,380)	(33,294)
Reclassification adjustment for gain on terminated interest rate swap included in net income	0	(67)	0	(67)
Foreign currency translation adjustments	26,680	(820)	(12,010)	4,522
Supplemental benefit plans adjustments, net of tax	(75)	(150)	112	(299)
Total other comprehensive income/(loss)	25,115	(22,125)	(50,278)	(29,138)
Comprehensive income/(loss)	$ 84,120	$ (27,697)	$ 42,546	$ (33,023)