Loss And Loss Adjustment Expense Reserves (Loss And LAE Activity) (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	$ 46	$ 12	$ 40	$ 62
Weighted average risk-free rate used to discount claim liability	1.89%
Insurance loss recoverable	$ 483		483		$ 533
CDO Portfolio [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	33		35
CDO Portfolio [Member] | Variable Interest Entity Primary Beneficiary [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Elimination Of Loss And LAE Expense (Benefit) As Result Of Consolidating VIEs	(21)		(13)
Second Lien Residential Mortgage Backed Securities And Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	36	47	29	72
First Lien Residential Mortgage Backed Securities [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	(26)	(3)	(16)	27
Financial Guarantee [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Aggregate CDO Loss And LAE Reserves	145		145		111
Financial Guarantee [Member] | CDO Portfolio [Member] | Variable Interest Entity Primary Beneficiary [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Elimination Of Loss And Lae Reserves As Result Of Consolidating VIEs	212		212		225
Loss And Lae Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Reserves for expected future claim payments	719		719		653
Expected recoveries of future payments	219		219		147
Recoveries On Unpaid Losses [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Expected recoveries of future payments	219		219		147
Insurance Loss Recoverable [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance loss recoverable	483		483
Insurance Loss Recoverable [Member] | Classified [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance claim loss recoverable	483		483		533
Insurance loss recoverable	483		483		533
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	388		388		$ 379
Remedial Actions For Insured Obligations [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	$ 7	$ 30	$ 5	$ 34