Credit Arrangements and Debt Obligations - Effect of Derivatives on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Amount of gain (loss) recognized in other comprehensive income (loss)
Cash flow hedges	$ (1,015)	$ (960)	$ (7,536)	$ (9,409)
Income tax effect	273	258	2,027	2,531
Net of income taxes	(742)	(702)	(5,509)	(6,878)
Amount of net gain (loss) reclassified into earnings
Interest expense — net	(1,468)	443	(3,109)	1,923
Income tax expense	395	(119)	837	(517)
Net of income taxes	(1,073)	324	(2,272)	1,406
Total effect on other comprehensive income (loss)
Interest expense — net	453	(1,403)	(4,427)	(11,332)
Income tax expense	(122)	377	1,190	3,048
Net of income taxes	$ 331	$ (1,026)	$ (3,237)	$ (8,284)