Loss And Loss Adjustment Expense Reserves (Schedule Of Present Value Of The Probability-Weighted Future Claim Payments And Recoveries) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Loss Reserves Claim Liability [Member] | Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loss and loss adjustment expense reserves	$ 635	$ 790
Lae Reserves [Member] | Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loss and loss adjustment expense reserves	53	63
Loss And Lae Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loss and loss adjustment expense reserves	688	853
Loss And Lae Reserves [Member] | Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loss and loss adjustment expense reserves	688	853
Insurance Loss Recoverable [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance loss recoverable	(742)	(3,648)
Insurance Loss Recoverable [Member] | Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance claim loss recoverable	(737)	(3,610)
LAE insurance loss recoverable	(5)	(38)
Insurance loss recoverable	(742)	(3,648)
Reinsurance recoverable on unpaid losses	7	14
Reinsurance recoverable on unpaid LAE	0	0
Reinsurance recoverable on paid losses	0	1
Reinsurance recoverable on paid and unpaid losses	$ 7	$ 15