Pension Benefit Obligations - Benefit Obligation (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
United States
Change in benefit obligation:
Benefit obligation at beginning of year	$ 265.4	$ 283.9	$ 275.6
Participant contributions	0.1	0.1
Interest cost	4.7	4.3	6.8
Benefits and expenses paid	(18.4)	(18.5)	(18.4)
Actuarial (gain) loss	(51.9)	(3.7)	22.0
Plan settlements	(1.8)	(0.7)	(2.1)
Benefit obligation at end of year	198.1	265.4	283.9
International.
Change in benefit obligation:
Benefit obligation at beginning of year	1,470.8	1,440.3	1,311.3
Service cost	0.5	0.5	0.6
Participant contributions	0.3	0.3	0.3
Interest cost	24.1	21.6	22.4
Benefits and expenses paid	(44.3)	(48.6)	(42.9)
Actuarial (gain) loss	(458.1)	(4.7)	82.8
Plan settlements	(2.2)	(5.9)	(4.1)
Plan amendments		0.4
Foreign currency translation (gain) loss	(199.9)	66.9	69.9
Benefit obligation at end of year	$ 791.2	$ 1,470.8	$ 1,440.3

Amount of cost recognized for passage of time related to defined benefit plan.

No definition available.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of contributions received by defined benefit plan from participant which increase benefit obligation.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

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Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of (increase) decrease to benefit obligation of defined benefit plan from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Includes, but is not limited to, lump-sum cash payment to participant in exchange for right to receive specified benefits, purchase of nonparticipating annuity contract and change from remeasurement.

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