Goodwill and Intangibles, including DAC and VOBA - Summary of Changes in Carrying Amounts of Goodwill and Intangible Assets Including FGL's DAC and VOBA Balances (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Intangible Assets, Including Goodwill [Roll Forward]
Beginning Balance, Goodwill	$ 1,476.7
Beginning Balance, Indefinite Lived Intangible Assets	1,178.1
Beginning Balance, Finite Lived Intangible Assets	985.1
Beginning Balance, Intangible Assets, Excluding Goodwill	2,729.1
Goodwill, Acquired During Period	3.5
Acquisitions (Note 3), Indefinite Lived Intangible Assets
Acquisitions (Note 13)
Deferrals	52.6
Less: Components of amortization:
Amortization of intangibles	43.4	86.6
Adjustment for unrealized investment (gains), net, Goodwill	7.9
Effect of translation, Goodwill	(4.0)
Effect of translation, Indefinite Lived intangible assets	3.4
Effect of translation, Intangible Assets Excluding Goodwill	3.5
Ending Balance, Goodwill	1,476.2
Ending Balance, Indefinite Lived Intangible Assets	1,181.5
Ending Balance, Finite Lived Intangible Assets	965.0
Ending Balance, Intangible Assets, Excluding Goodwill	2,749.7
Unlocking [Member]
Less: Components of amortization:
Goodwill Amortization
Indefinite Lived Intangible Assets, Amortization
Amortization of intangibles	(15.2)
Reclassifications [Member]
Less: Components of amortization:
Goodwill Amortization
Indefinite Lived Intangible Assets, Amortization
Amortization of intangibles
Interest [Member]
Less: Components of amortization:
Goodwill Amortization
Indefinite Lived Intangible Assets, Amortization
Amortization of intangibles	(7.0)
Periodic amortization [Member]
Less: Components of amortization:
Goodwill Amortization
Indefinite Lived Intangible Assets, Amortization
Amortization of intangibles	65.6
Definite Lived Intangible Assets [Member]
Intangible Assets, Including Goodwill [Roll Forward]
Beginning Balance, Finite Lived Intangible Assets	985.1
Acquisitions (Note 3), Finite-Lived Intangible Assets
Deferrals
Less: Components of amortization:
Amortization of intangibles	20.2	17.1
Adjustment for unrealized investment (gains), net, Goodwill
Effect of translation, Finite Lived intangible assets	0.1
Ending Balance, Finite Lived Intangible Assets	965.0
Definite Lived Intangible Assets [Member] | Unlocking [Member]
Less: Components of amortization:
Amortization of intangibles
Definite Lived Intangible Assets [Member] | Reclassifications [Member]
Less: Components of amortization:
Amortization of intangibles
Definite Lived Intangible Assets [Member] | Interest [Member]
Less: Components of amortization:
Amortization of intangibles
Definite Lived Intangible Assets [Member] | Periodic amortization [Member]
Less: Components of amortization:
Amortization of intangibles	20.2
VOBA [Member]
Intangible Assets, Including Goodwill [Roll Forward]
Beginning Balance, Finite Lived Intangible Assets	225.3
Acquisitions (Note 3), Finite-Lived Intangible Assets
Deferrals
Less: Components of amortization:
Amortization of intangibles	13.2	58.9
Adjustment for unrealized investment (gains), net, Goodwill	1.6
Effect of translation, Finite Lived intangible assets
Ending Balance, Finite Lived Intangible Assets	213.7
VOBA [Member] | Unlocking [Member]
Less: Components of amortization:
Amortization of intangibles	(11.8)
VOBA [Member] | Reclassifications [Member]
Less: Components of amortization:
Amortization of intangibles
VOBA [Member] | Interest [Member]
Less: Components of amortization:
Amortization of intangibles	(3.7)
VOBA [Member] | Periodic amortization [Member]
Less: Components of amortization:
Amortization of intangibles	28.7
DAC [Member]
Intangible Assets, Including Goodwill [Roll Forward]
Beginning Balance, Finite Lived Intangible Assets	340.6
Acquisitions (Note 3), Finite-Lived Intangible Assets
Deferrals	52.6
Less: Components of amortization:
Amortization of intangibles	10.0	10.6
Adjustment for unrealized investment (gains), net, Goodwill	6.3
Effect of translation, Finite Lived intangible assets
Ending Balance, Finite Lived Intangible Assets	389.5
DAC [Member] | Unlocking [Member]
Less: Components of amortization:
Amortization of intangibles	(3.4)
DAC [Member] | Reclassifications [Member]
Less: Components of amortization:
Amortization of intangibles
DAC [Member] | Interest [Member]
Less: Components of amortization:
Amortization of intangibles	(3.3)
DAC [Member] | Periodic amortization [Member]
Less: Components of amortization:
Amortization of intangibles	16.7
Goodwill [Member]
Intangible Assets, Including Goodwill [Roll Forward]
Deferrals
Less: Components of amortization:
Adjustment for unrealized investment (gains), net, Goodwill
Indefinite Lived Intangible Assets [Member]
Intangible Assets, Including Goodwill [Roll Forward]
Deferrals
Less: Components of amortization:
Adjustment for unrealized investment (gains), net, Goodwill