Basis of Presentation, Significant Accounting Polices and Practicies and Recent Accounting Pronouncements Basis of Presentation - Additional Information (Details) $ in Millions	3 Months Ended
	Dec. 31, 2015 USD ($) $ / MMBTU	Dec. 31, 2014 USD ($)	Sep. 30, 2015 USD ($)	Apr. 06, 2011 USD ($)
Basis of Presentation [Line Items]
Deferred Finance Costs, Net	$ 100.2		$ 102.9
Asset Impairment Charges	63.2	$ 249.8
Impairment of Proved Oil and Gas Properties	54.4	190.0
Energy Segment [Member]
Basis of Presentation [Line Items]
Asset Impairment Charges	$ 54.4	$ 190.0
FGL [Member]
Basis of Presentation [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	19.60%
Statutory Accounting Practices, Statutory Capital and Surplus, Increase (Decrease) as a Result of ReDomestication by Entity	$ 41.9
Statutory Accounting Practices, Statutory Capital and Surplus, Unassigned Balance Netted Against Additional Paid in Capital				$ 806.0
Raven Re [Member]
Basis of Presentation [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	220.0		226.3
Statutory Accounting Practices, Permitted Practice, Change in Statutory Capital and Surplus	4.1		2.5
Statutory Accounting Practices, Non-Permitted Practice, Change in Statutory Capital and Surplus	13.7		33.1
Statutory Accounting Practices, Statutory Capital and Surplus, Change in Permitted Practice to Non-Permitted, Balance	$ 210.3		$ 195.6
Natural Gas [Member]
Basis of Presentation [Line Items]
Average Sales Prices | $ / MMBTU	2.59
Accounting Standards Update 2015-17 [Member]
Basis of Presentation [Line Items]
Deferred Tax Assets, Net	$ 39.1