Long-Term Debt - Repayments (Details) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)
Debt Disclosure [Abstract]
Debt Covenant, Leverage Ratio	4.25		4.25
Debt Covenant, Percentage of Revolving Credit Commitments	30.00%		30.00%
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt	$ 1,185.6	$ 50.6	$ 1,256.5	$ 151.7
Gross Exchanges of Long-term debt	$ 0.0	0.0	$ 0.0	99.9
Debt Covenant, Leverage Ratio	4.25		4.25
Debt Covenant, Percentage of Revolving Credit Commitments	30.00%		30.00%
Loss on extinguishment of debt and refinancing fees, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums	$ 1.7	(6.5)	$ (1.6)	(16.9)
Write off of Debt Issuance Costs and Deferred Financing Fees	3.2	0.4	3.4	2.1
Write-off of Unamortized Debt Discount/(Premium)	(4.6)	0.0	(4.6)	0.0
Municipal Bonds
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt	1.1	1.1	1.1	1.1
Gross Exchanges of Long-term debt	0.0	0.0	0.0	0.0
Municipal Bonds \| Loss on extinguishment of debt and refinancing fees, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums	0.0	0.0	0.0	0.0
Write off of Debt Issuance Costs and Deferred Financing Fees	0.0	0.0	0.0	0.0
Write-off of Unamortized Debt Discount/(Premium)	0.0	0.0		0.0
Revolving Credit Facility
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt	300.0		345.0
Gross Exchanges of Long-term debt	0.0		0.0
Revolving Credit Facility \| Loss on extinguishment of debt and refinancing fees, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums	0.0		0.0
Write off of Debt Issuance Costs and Deferred Financing Fees	0.0		0.0
Write-off of Unamortized Debt Discount/(Premium)	0.0		0.0
4.50% Senior Notes Maturing in September 2031 \| Senior Notes
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt	25.2	49.5	51.1	120.5
Gross Exchanges of Long-term debt	0.0	0.0	0.0	0.0
4.50% Senior Notes Maturing in September 2031 \| Senior Notes \| Loss on extinguishment of debt and refinancing fees, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums	(2.7)	(6.5)	(6.0)	(16.9)
Write off of Debt Issuance Costs and Deferred Financing Fees	0.2	0.4	0.4	1.0
Write-off of Unamortized Debt Discount/(Premium)	0.0	$ 0.0	0.0	0.0
5.75% Senior Notes Maturing March 2027 \| Senior Notes
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt	459.3		459.3
Gross Exchanges of Long-term debt	0.0		0.0
5.75% Senior Notes Maturing March 2027 \| Senior Notes \| Loss on extinguishment of debt and refinancing fees, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums	4.4		4.4
Write off of Debt Issuance Costs and Deferred Financing Fees	1.6		1.6
Write-off of Unamortized Debt Discount/(Premium)	(4.6)		(4.6)
Third Incremental Term Loan \| Term Loan
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt				30.1
Gross Exchanges of Long-term debt				99.9
Third Incremental Term Loan \| Term Loan \| Loss on extinguishment of debt and refinancing fees, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums				0.0
Write off of Debt Issuance Costs and Deferred Financing Fees				1.1
Write-off of Unamortized Debt Discount/(Premium)				$ 0.0
Fourth Incremental Term Loan \| Term Loan
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt	400.0		400.0
Gross Exchanges of Long-term debt	0.0		0.0
Fourth Incremental Term Loan \| Term Loan \| Loss on extinguishment of debt and refinancing fees, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums	0.0		0.0
Write off of Debt Issuance Costs and Deferred Financing Fees	1.4		1.4
Write-off of Unamortized Debt Discount/(Premium)	$ 0.0		$ 0.0