Loss And Loss Adjustment Expense Reserves (Summary Of Credit Impairments Related To Derivatives) (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2013 securityloan
Loss And Loss Adjustment Expense Reserves [Line Items]
Discount rate of credit impairments	5.09%
Proprietary performance data on CRE loans, amount from 1992 to 2011				80,000
Additional estimated credit impairment on Cmbs derivatives	$ 601,000,000
Aggregate ITD credit impairment on Cmbs derivatives since 2010	4,200,000,000
Cmbs severities exceeded complete loss in certain instances	100.00%
Policyholder (Benefits) And Claims Incurred Net	117,000,000	50,000,000	(80,000,000)
Commercial Real Estate Collateralized Debt Obligations [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	$ (33,000,000)
Minimum [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Percentage of loss on liquidation	1.00%
Maximum [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Percentage of loss on liquidation	2.00%