Derivative Financial Instruments - Notional Amounts (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Interest rate swap contract | Derivatives designated as hedging instruments:
Derivative [Line Items]
Derivative notional amount	$ 552,015	$ 555,210
Foreign exchange contracts | Buy | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Derivative notional amount	4,250	4,225
Foreign exchange contracts | Sell | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Derivative notional amount	$ 29,290	$ 23,235