Loss And Loss Adjustment Expense Reserves (Present Value Of Probability-Weighted Future Claim Payments And Recoveries) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loss Reserves (Claim Liability) [Member] \| Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loss and loss adjustment expense reserves	$ 790	$ 781
LAE Reserves [Member] \| Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loss and loss adjustment expense reserves	63	55
Loss And LAE Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loss and loss adjustment expense reserves	853	836	1,129
Loss And LAE Reserves [Member] \| Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loss and loss adjustment expense reserves	853	836
Insurance Loss Recoverable [Member] \| Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance claim loss recoverable	(3,610)	(3,032)
LAE insurance loss recoverable	(38)	(14)
Insurance loss recoverable	(3,648)	(3,046)
Reinsurance recoverable on unpaid losses	14	15
Reinsurance recoverable on paid losses	1	1
Reinsurance recoverable on paid and unpaid losses	$ 15	$ 16

The sum for all reinsurance arrangements of the known and estimated amount recoverable as of the balance sheet date from a given reinsurer for claims paid or incurred by the ceding insurer and associated claims settlement expenses for each reinsurance arrangement (or, the sum of all cases determined individually, probably applying different assumptions to each arrangement).

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The portion of reinsurance receivables representing the aggregate amount of estimated amounts due as of the balance sheet date from another insurer; also called reinsurance recoverables or unpaid losses recoverable, that are expected based upon statistical projections of incurred claims and claims settlement expenses which have not yet been reported to the insurer.

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- Definition

Receivables currently due from reinsurers for ceded claims paid.

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- Definition

Alternate concept name for the aggregate amount of policy reserves (provided for future obligations including unpaid claims and claims adjustment expenses) and policy benefits (liability for future policy benefits) as of the balance sheet date; grouped amount of all the liabilities associated with the company's insurance policies.

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