Pension Benefit Obligations - Excess of Plan Assets (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
United States
Additional year-end information for pension plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	$ 168.8	$ 184.8	$ 247.8
Accumulated benefit obligation	168.8	184.8	247.8
Fair value of plan assets	98.8	101.4	138.9
Expected employer contributions in next fiscal year	12.9
International
Additional year-end information for pension plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	628.1	601.4	1,248.8
Accumulated benefit obligation	628.1	600.1	1,243.9
Fair value of plan assets	506.5	$ 456.9	$ 982.4
Expected employer contributions in next fiscal year	$ 22.2

Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year.

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Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

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Amount of plan asset for defined benefit plan with accumulated benefit obligation in excess of plan assets.

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