Goodwill and Intangibles, including DAC and VOBA, net - Summary of Definite Lived Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified			12 Months Ended				12 Months Ended				12 Months Ended				12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Minimum	Sep. 30, 2014 Maximum	Sep. 30, 2014 Customer relationships	Sep. 30, 2013 Customer relationships	Sep. 30, 2014 Customer relationships Minimum	Sep. 30, 2014 Customer relationships Maximum	Sep. 30, 2014 Trade names	Sep. 30, 2013 Trade names	Sep. 30, 2014 Trade names Minimum	Sep. 30, 2014 Trade names Maximum	Sep. 30, 2014 Technology assets	Sep. 30, 2013 Technology assets	Sep. 30, 2014 Technology assets Minimum	Sep. 30, 2014 Technology assets Maximum
Finite-Lived Intangible Assets [Line Items]
Cost	$ 1,240.4	$ 1,229.6			$ 877.1	$ 885.9			$ 171.1	$ 171.6			$ 192.2	$ 172.1
Accumulated Amortization	(323.2)	(244.5)			(204.6)	(160.8)			(61.0)	(44.7)			(57.6)	(39.0)
Net	$ 917.2	$ 985.1			$ 672.5	$ 725.1			$ 110.1	$ 126.9			$ 134.6	$ 133.1
Amortizable Life			1 year	20 years			15 years	20 years			1 year	12 years			4 years	17 years