Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net earnings	$ 271,623	$ 258,047	$ 215,076
Other comprehensive income (loss):
Foreign currency translation adjustments	(22,576)	(10,604)	19,299
Interest rate caps, net of tax	(4,566)	2,449	(1,084)
Foreign exchange contracts, net of tax	(154)
Other comprehensive income (loss), net of tax	(27,296)	(8,155)	18,215
Total comprehensive income	$ 244,327	$ 249,892	$ 233,291