Divestitures - Schedule of Intercompany Assets and Liabilities of Business Held for Sale (Details) - USD ($) $ in Millions	Mar. 31, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred charges and other assets	$ 60.8	$ 43.7
Disposal Group, Including Discontinued Operation, Assets, Current	1,976.0	28,929.2
Assets	8,240.3	35,849.7
Long Term Debt Current And Non Current	5,318.7	5,705.1
Accounts Payable and Accrued Liabilities, Current	360.7	373.1
Other long-term liabilities	101.1	26.2
Disposal Group, Including Discontinued Operation, Liabilities, Current	558.6	26,851.3
Liabilities	$ 6,896.6	$ 33,902.8