Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022		Sep. 30, 2021	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Hedging collateral deposits	$ 0	$ 91,670	[1]	$ 88,610	$ 0

[1] Netting Adjustments represent the impact of legally-enforceable master netting arrangements that allow the Company to net gain and loss positions held with the same counterparties. The net asset or net liability for each counterparty is recorded as an asset or liability on the Company’s balance sheet.