Unaudited Quarterly Results - Additional Information (Detail) $ in Millions	3 Months Ended
	Dec. 31, 2014 USD ($)
Interim Period, Costs Not Allocable
Reserve Increase for Long-term Care	$ 698.2
Reserve Charge for Long-term Care Product, After Tax	453.8
Pension Settlement Loss
Interim Period, Costs Not Allocable
Non-operating Retirement-related Loss	64.4
Non-operating Retirement Related Loss, After Tax	$ 41.9