Fair Value of Financial Instruments - Additional Information (Detail) $ in Millions	3 Months Ended
Dec. 31, 2015 USD ($)
Front Street Future Policyholder Benefits Reserve [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change In Fair Value Of Derivatives	$ 7.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Balance Type:	na
Period Type:	duration