Reinsurance - Effect of Reinsurance on Premiums Earned, Benefits Incurred and Reserve Changes (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Reinsurance Disclosures [Abstract]
Document Period End Date	Dec. 31, 2013
Insurance Premiums:
Direct	$ 67.7	$ 72.4
Assumed	9.3	12.1
Ceded	(63.1)	(70.7)
Net	13.9	13.8
Benefits and Other Changes in Insurance Policy Reserves:
Direct	296.4	139.6
Assumed	5.4	6.5
Ceded	(67.1)	(62.5)
Net	$ 234.7	$ 83.6