Information Regarding Concentration of Reinsurance Recoverables and Ratings Profile of its Reinsurers (Parenthetical) (Detail)	Sep. 30, 2012
Ceded Credit Risk [Line Items]
Percentage reinsurance recoverables	100.00%	[1]
A (Excellent) or higher
Ceded Credit Risk [Line Items]
Percentage reinsurance recoverables	92.10%

[1] Reinsurance recoverables reflect amounts due from one or more reinsurance subsidiaries of the listed company.