Loss And Loss Adjustment Expense Reserves (Loss And LAE Activity) (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	$ 117,000,000	$ 50,000,000	$ (80,000,000)
Losses and loss adjustment expense payments, net of reinsurance	433,000,000
Decrease in insurance loss recoverable related to paid losses	3,000,000,000
Weighted average risk-free rate used to discount claim liability	2.37%	1.38%
Loss and loss adjustment expense collections, net of reinsurance	2,900,000,000
Losses and LAE related to actual and expected payments	98,000,000
U S Public Finance Insurance [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Losses and loss adjustment expense payments, net of reinsurance	143,000,000
Abs Cdo Portfolio [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
ABS CDO exposure decrease since December 31,2007	96.00%
Policyholder (Benefits) And Claims Incurred Net	(24,000,000)
Elimination Of Loss And LAE Expense As Result Of Consolidating VIE	9,000,000
Rmbs And Heloc And Ces [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Reduction of excess interest cash flows from securitizations	207,000,000
Losses and loss adjustment expense payments, net of reinsurance	196,000,000
Loss and loss adjustment expense collections, net of reinsurance	2,800,000,000
Rmbs And Heloc And Ces [Member] | Ineligible Loan Recoveries [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Change in recoveries of actual and expected payments primarily related to ineligible mortgages	317,000,000
Second Lien Residential Mortgage Backed Securities And Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	(2,000,000)
Elimination Of Loss And LAE Expense As Result Of Consolidating VIE	50,000,000
Insurance claim loss recoverable		3,600,000,000
Losses and LAE related to actual and expected payments	108,000,000
First Lien Residential Mortgage Backed Securities [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	(70,000,000)
Elimination Of Loss And LAE Expense As Result Of Consolidating VIE	3,000,000
Losses and LAE related to actual and expected payments	(60,000,000)
Financial Guarantee [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Aggregate ABS CDO Loss And LAE Reserves	115,000,000
Financial Guarantee [Member] | Variable Interest Entity Primary Beneficiary [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Aggregate ABS CDO Loss And LAE Reserves	226,000,000
Loss And Lae Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Reserves for expected future claim payments	847,000,000	1,200,000,000
Expected recoveries of future payments	206,000,000	332,000,000
Recoveries On Unpaid Losses [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Expected recoveries of future payments	206,000,000	332,000,000	562,000,000
Insurance Loss Recoverable [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance loss recoverable	694,000,000	3,648,000,000	3,046,000,000
Insurance Loss Recoverable [Member] | Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance claim loss recoverable	694,000,000	3,610,000,000
Insurance loss recoverable	694,000,000	3,648,000,000
Insurance Loss Recoverable [Member] | Second Lien Residential Mortgage Backed Securities And Reserves [Member] | Ineligible Loan Recoveries [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance loss recoverable		2,500,000,000
Loan Repurchase Commitments [Member] | Second Lien Residential Mortgage Backed Securities And Reserves [Member] | Variable Interest Entity Primary Beneficiary [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loan repurchase commitments		1,100,000,000
Loan Repurchase Commitments [Member] | Second Lien Residential Mortgage Backed Securities And Reserves [Member] | Ineligible Loan Recoveries [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Total estimated insurance recoveries	$ 359,000,000