Supplemental Information (Other Noncurrent Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Supplemental Information [Abstract]
Pension benefits	$ 417.2	$ 703.8
Postretirement benefits	47.0	57.0
Other employee benefits	94.4	99.3
Noncurrent customer liability	92.4	62.6
Long-term accrued income taxes related to U.S. tax reform	184.4	0.0
Contingencies related to uncertain tax positions	113.2	130.6
Advance payments	58.2	39.0
Environmental liabilities	64.6	72.3
Derivative instruments	39.9	36.0
Asset retirement obligations	189.5	144.0
Obligation for future contribution to an equity affiliate	94.4	94.4
Obligations associated with EfW	63.3	65.3
Other	78.4	107.6
Other noncurrent liabilities	$ 1,536.9	$ 1,611.9

Other employee benefits not separately dislcosed

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The amounts due to customers for utilities used in the normal course of business for a sum of money expected to be payable at a future date more than one year from the balance sheet date.

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Amount of tax liability from transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act of 2017, classified as noncurrent.

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Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable after twelve months or beyond the next operating cycle if longer.

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Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

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Amount of liability, recognized in statement of financial position, for defined benefit pension plan, classified as noncurrent. Excludes other postretirement benefit plan.

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Amount of liability, recognized in statement of financial position, for defined benefit other postretirement plan, classified as noncurrent. Excludes pension plan.

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Obligations not otherwise itemized or categorized in the footnotes to the financial statements that are expected to be paid after one year (or the normal operating cycle, if longer), from the balance sheet date.

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