Commitments and Contingencies - Letters of Credit (Details) - USD ($)	Sep. 30, 2023	Sep. 30, 2022
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 325,000,000
Line of Credit
Debt Instrument [Line Items]
Letters of credit outstanding	9,800,000	$ 11,300,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 325,000,000