Divestitures - Schedule of Assets and Liabilities of Business Held for Sale (Details) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, Discontinued Operation, Liabilities, Current		$ 398.6
Disposal group, Discontinued Operation, Assets, Current	$ 0.0	343.1
Cash and cash equivalents	497.3	661.2	$ 728.8	$ 677.0
Receivables, net (Note 9)	556.3	613.9
Other assets (Note 13)	172.6	412.0
Debt (Note 15)	5,430.9	5,984.6
Accounts payable and other current liabilities (Note 14)	989.8	1,062.0
Other liabilities	32.0	56.3
Compass Production Partners G.P. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents		34.0
Receivables, net (Note 9)		19.1
Property, Plant and Equipment including Oil and Gas Property, Net		288.9
Other assets (Note 13)		1.1
Debt (Note 15)		325.9
Accounts payable and other current liabilities (Note 14)		33.6
Other liabilities		39.1
FGL [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Investment	21,140.9	19,206.7
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	863.9	501.8
Disposal Group, Including Discontinued Operation, Accrued Investment Income	213.7	191.2
Disposal Group, Including Discontinued Operation, Reinsurance Recoverable	3,463.9	3,578.7
Disposal Group, Including Discontinued Operation, Deferred Tax Assets	0.0	189.1
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment	18.5	14.4
Disposal Group, Including Discontinued Operation, Intangible Assets	1,065.5	1,048.6
Disposal Group, Including Discontinued Operation, Other Assets	335.1	246.0
Disposal Group, Including Discontinued Operation, Write-down of assets held for sale to fair value less costs to sell	(362.8)	0.0
Disposal Group, Including Discontinued Operation, Assets	26,738.7	24,976.5
Disposal Group, Including Discontinued Operation, Insurance Reserves	23,944.6	22,560.1
Disposal Group, Including Discontinued Operation, Debt	398.8	295.9
Disposal Group, Including Discontinued Operation, Accounts Payable and Accrued Liabilities	57.0	43.7
Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities, Current	9.9	0.0
Disposal Group, Including Discontinued Operation, Other Liabilities	689.9	518.8
Disposal Group, Including Discontinued Operation, Liabilities	$ 25,100.2	$ 23,418.5