Derivative Financial Instruments - Effect of Derivative Instruments on the Consolidated Statement of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Derivatives designated as hedging instruments | Interest rate swap contract | Interest expense, net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
(Loss) Gain Recognized in Consolidated Statements of (Loss) Income	$ (4,835)	$ (9,360)	$ 524
Derivatives designated as hedging instruments | Terminated interest rate swap contract | Interest expense, net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
(Loss) Gain Recognized in Consolidated Statements of (Loss) Income	(9,287)	0	0
Derivatives not designated as hedging instruments | Foreign exchange contracts | Other expense, net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
(Loss) Gain Recognized in Consolidated Statements of (Loss) Income	$ (794)	$ (222)	$ 28