Divestitures Divestitures - Additional Information (Details) - USD ($) $ in Millions			3 Months Ended		6 Months Ended
		Dec. 01, 2015	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax			$ 13.0		$ 13.0
Gain (Loss) on Disposition of Oil and Gas Property			0.0	$ 0.0	105.6	$ 0.0
FGL [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred Tax Assets, Valuation Allowance			237.7		237.7
Discontinued Operation, Tax Effect of Discontinued Operation, Deferred Taxes, Current	[1]				90.9
Deferred Tax Liabilities, Parent's Basis in Discontinued Operation			328.6		328.6
Business Acquisition, Termination Fee Payable for Termination of Merger Agreement			51.5		51.5
Disposal Group, Including Discontinued Operation, Write-down of assets held for sale to fair value less costs to sell			(23.5)		(23.5)		$ 0.0
Compass Production Partners [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transaction costs, Sale of Oil and Gas Properties		$ 1.9
Proceeds from Sale of Oil and Gas Property and Equipment		$ 147.5			4.5
Gain (Loss) on Disposition of Oil and Gas Property					105.6
Majority-Owned Subsidiary, Unconsolidated [Member] | FGL [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Interest Income			$ 1.2	$ 0.6	$ 2.3	$ 2.3

[1] (b) Included in the income tax expense for the six months ended March 31, 2016 was a $90.9 of net income tax expense related to the establishment of a deferred tax liability of $328.6 at March 31, 2016 as a result of classifying the Company’s ownership interest in FGL as held for sale. The deferred tax liability was partially offset by a $237.7 reduction of valuation allowance on HRG’s net operating and capital loss carryforwards expected to offset the FGL taxable gain at March 31, 2016. The remaining liability is expected to be offset by current year losses recognized in Continuing Operations except for $13.0 of estimated alternative minimum taxes.