Derivative Financial Instruments - Effect of Derivative Instruments on the Consolidated Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Derivatives designated as hedging instruments | Interest rate swap contract | Interest expense
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) Recognized in Statement of Income	$ (2,445)	$ (1,170)
Derivatives designated as hedging instruments | Terminated interest rate swap contract | Interest expense
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) Recognized in Statement of Income	(929)	0
Derivatives not designated as hedging instruments | Foreign exchange contracts | Other income (expense), net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) Recognized in Statement of Income	$ 122	$ 6