Debt - Senior Credit Agreement (Details)	1 Months Ended	12 Months Ended
	Dec. 31, 2022 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Debt Instrument [Line Items]
Repayments of Debt		$ 698,800,000	$ 920,900,000	$ 38,100,000
Debt, gross		1,099,400,000
Secured Debt | Line of Credit
Debt Instrument [Line Items]
Debt, gross		439,400,000
Payments for Loans		23,800,000	11,900,000
Revolver | Line of Credit
Debt Instrument [Line Items]
Interest Expense, Debt			1,100,000
Debt, gross		$ 125,000,000.0	0
2022 Credit Facilities
Debt Instrument [Line Items]
Principal amount of line of credit	$ 950,000,000.0
2022 Credit Facilities | Minimum | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		1.375%
2022 Credit Facilities | Minimum | Base Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		0.375%
2022 Credit Facilities | Maximum | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		2.25%
2022 Credit Facilities | Maximum | Base Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		1.25%
2022 Credit Facilities | Line of Credit
Debt Instrument [Line Items]
Maximum consolidated leverage ratio		4.5
Minimum consolidated interest coverage ratio		3.0
2022 Term Loans | Secured Debt | Line of Credit
Debt Instrument [Line Items]
Principal amount of line of credit	$ 475,000,000.0
Term of debt	5 years
Debt Instrument, Periodic Payment		$ 5,900,000
2022 Revolver | Revolver | Line of Credit
Debt Instrument [Line Items]
Principal amount of line of credit	$ 475,000,000.0
Term of debt	5 years
Line of credit, sublimit	$ 100,000,000.0
Remaining borrowing capacity		346,800,000
2019 Term Loans | Revolver | Line of Credit
Debt Instrument [Line Items]
Repayments of Debt		445,600,000
2019 Credit Facilities | Revolver | Line of Credit
Debt Instrument [Line Items]
Repayments of Debt		290,000,000.0
Term Loan | Secured Debt | Line of Credit
Debt Instrument [Line Items]
Debt, gross		439,400,000	$ 463,100,000
Term Loan | Revolver | Line of Credit
Debt Instrument [Line Items]
Letters of credit outstanding		$ 3,200,000