Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment owned, foreign currency contract, current value	$ 29.7	$ 150.5
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, notional amount matured	175.0
Outstanding derivative contracts notional amount	$ 175.0