Fair Value Measurements - Schedule of Assets and Liabilities at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2023	Sep. 30, 2023
Foreign Exchange Contract | Not Designated as Hedging Instrument
Accrued expenses and other liabilities
Derivative, notional amount		$ 29.7
Level 1
Other noncurrent assets
Total assets at fair value	$ 255.8	19.6
Accrued expenses and other liabilities
Total liabilities at fair value	0.0	0.0
Level 2
Other noncurrent assets
Total assets at fair value	96.1	285.2
Accrued expenses and other liabilities
Total liabilities at fair value	0.0	0.1
NAV (a)
Other noncurrent assets
Total assets at fair value	1.9	2.1
Accrued expenses and other liabilities
Total liabilities at fair value	23.0	20.8
Fair Value, Measurements, Recurring
Prepaid Expense and Other Assets, Current [Abstract]
Currency derivatives		0.1
Other noncurrent assets
Non-qualified trust funds	1.9	2.1
Deferred compensation investments	20.6	19.0
Total assets at fair value	353.8	306.9
Accrued expenses and other liabilities
Currency derivatives		0.1
Deferred compensation obligations	23.0	20.8
Total liabilities at fair value	23.0	20.9
Fair Value, Measurements, Recurring | Money market funds
Cash and cash equivalents
Cash and cash equivalents	235.2	0.6
Fair Value, Measurements, Recurring | Time deposits
Cash and cash equivalents
Cash and cash equivalents	90.9	277.3
Fair Value, Measurements, Recurring | Prepaid expenses and other current assets
Prepaid Expense and Other Assets, Current [Abstract]
Interest rate swap agreements	5.2	7.8
Fair Value, Measurements, Recurring | Level 1
Other noncurrent assets
Deferred compensation investments	20.6	19.0
Fair Value, Measurements, Recurring | Level 1 | Money market funds
Cash and cash equivalents
Cash and cash equivalents	235.2	0.6
Fair Value, Measurements, Recurring | Level 2
Prepaid Expense and Other Assets, Current [Abstract]
Currency derivatives		0.1
Other noncurrent assets
Non-qualified trust funds	0.0	0.0
Accrued expenses and other liabilities
Currency derivatives		0.1
Fair Value, Measurements, Recurring | Level 2 | Time deposits
Cash and cash equivalents
Cash and cash equivalents	90.9	277.3
Fair Value, Measurements, Recurring | Level 2 | Prepaid expenses and other current assets
Prepaid Expense and Other Assets, Current [Abstract]
Interest rate swap agreements	5.2	7.8
Fair Value, Measurements, Recurring | NAV (a)
Other noncurrent assets
Non-qualified trust funds	1.9	2.1
Accrued expenses and other liabilities
Deferred compensation obligations	$ 23.0	$ 20.8