Financing Agreements - Schedule of borrowings (Details) - USD ($)	Sep. 30, 2024	Feb. 14, 2024	Sep. 30, 2023	Jun. 08, 2022	Mar. 03, 2021	Jun. 16, 2020	Sep. 25, 2019	Dec. 15, 2014
Debt Instrument [Line Items]
Total debt	$ 1,893,000,000		$ 2,010,100,000
Less: current portion	20,600,000		19,700,000
Long-term debt	1,872,400,000		1,990,400,000
$400.0 senior unsecured notes
Debt Instrument [Line Items]
Debt issued	400,000,000					$ 400,000,000.0
350 Million Senior Unsecured Notes
Debt Instrument [Line Items]
Debt issued					$ 350,000,000
Total debt	347,100,000		346,600,000
Former Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 1,000,000,000
Term loans | 350 Million Senior Unsecured Notes
Debt Instrument [Line Items]
Unamortized debt issuance costs	1,200,000		1,800,000
Senior unsecured notes | $500 senior unsecured notes
Debt Instrument [Line Items]
Debt issued		$ 500,000,000
Total debt	494,600,000		0
Senior unsecured notes | $400.0 senior unsecured notes
Debt Instrument [Line Items]
Total debt	0		398,000,000.0
Unamortized debt issuance costs	5,400,000
Senior unsecured notes | $375.0 senior unsecured notes
Debt Instrument [Line Items]
Debt issued							$ 375,000,000
Total debt	373,600,000		372,900,000				$ 374,400,000
Unamortized debt issuance costs	1,200,000		2,000,000.0
$1,000 revolving credit facility (excluding outstanding letters of credit)
Debt Instrument [Line Items]
Total debt	298,500,000		505,100,000
Maximum borrowing capacity	681,200,000
$100.0 Series A Notes
Debt Instrument [Line Items]
Debt issued								$ 100,000,000.0
Unamortized debt issuance costs	2,900,000		3,400,000
Other
Debt Instrument [Line Items]
Total debt	$ 200,000		$ 0