Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net earnings	$ 113,245	$ 271,623	$ 258,047
Other comprehensive income (loss):
Foreign currency translation adjustments	11,821	(22,576)	(10,604)
Interest rate caps, net of tax	198	(4,566)	2,449
Foreign exchange contracts, net of tax	565	(154)
Other comprehensive income (loss), net of tax	12,584	(27,296)	(8,155)
Total comprehensive income	$ 125,829	$ 244,327	$ 249,892