Long-Term Debt - Additional Information (Details) - USD ($) $ in Millions							3 Months Ended		9 Months Ended
		Jul. 17, 2026	May 04, 2026	Jan. 29, 2025	Aug. 28, 2023	Dec. 18, 2013	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Sep. 30, 2025	Jun. 27, 2024
Debt Instrument [Line Items]
Loss on debt extinguishment	[1]						$ (9.8)	$ 0.0	$ (9.8)	$ (0.7)
Debt voluntary repayment									13.0	27.9
Debt borrowings during the period									104.5	14.5
Long-term debt, fair value							886.2		886.2		$ 796.8
Receivables Financing Agreement | Wholly-owned Subsidiary
Debt Instrument [Line Items]
Credit agreement, maximum borrowing capacity												$ 325.0
Weighted average interest rate												$ 50.0
Interest period term							89.9		89.9		82.3
Debt voluntary repayment									13.0	27.9
Debt borrowings during the period									105.1	14.5
SOFR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				0.50%
ABR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				1.50%
Series B Term Loan
Debt Instrument [Line Items]
Debt repayments							0.0	0.0	0.0	0.0
Credit Agreement | First Lien Credit Facility Term Loans
Debt Instrument [Line Items]
Credit agreement date						Dec. 18, 2013
Debt instrument, term						7 years
Credit agreement, maximum borrowing capacity						$ 1,460.0
Credit Agreement | First Lien Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, term						5 years
Credit agreement, maximum borrowing capacity						$ 210.0
Amended Credit Agreement
Debt Instrument [Line Items]
Loss on debt extinguishment		$ 9.7
Issue discount		$ 2.0
Debt instrument, effective interest rate		5.66%
Percentage of amortization debt payments		0.25%
Debt borrowings during the period					$ 450.0
Amended Credit Agreement | SOFR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				2.00%
Amended Credit Agreement | ABR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				1.00%
Amended Credit Agreement | First Lien Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, term						5 years
Credit agreement, maximum borrowing capacity						$ 300.0
Amended Credit Agreement | Series B Term Loan
Debt Instrument [Line Items]
Debt instrument, term						7 years
Credit agreement, maximum borrowing capacity						$ 1,200.0
Debt repayments		$ 738.0
Previous Revolving Credit Facility | First Lien Revolving Credit Facility
Debt Instrument [Line Items]
Interest period term							0.0		0.0		$ 0.0
Revolving Credit Facility
Debt Instrument [Line Items]
Loss on debt extinguishment			$ 0.1
Revolving Credit Facility | SOFR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			0.00%
Revolving Credit Facility | ABR
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			1.00%
Revolving Credit Facility | ABR | Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			1.25%
Revolving Credit Facility | ABR | Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			0.75%
Revolving Credit Facility | First Lien Revolving Credit Facility
Debt Instrument [Line Items]
Debt repayments							$ 0.0	$ 0.0	$ 0.0	$ 0.0
Debt instrument, maturity date			Apr. 22, 2031
Revolving Credit Facility | First Lien Revolving Credit Facility | SOFR | Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			2.25%
Revolving Credit Facility | First Lien Revolving Credit Facility | SOFR | Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate			1.75%

[1] Represents losses on the extinguishment of debt related to the Tenth Credit Agreement Amendment, the Eleventh Credit Agreement Amendment, and the Sixth Amendment to the Receivables Financing Agreement, in the nine months ended June 30, 2026, and the Ninth Credit Agreement Amendment, in the nine months ended June 30, 2025 and includes accelerated amortization of deferred financing fees and original issue discount as well as fees paid to lenders and third parties.