Loss And Loss Adjustment Expense Reserves (Loss And LAE Activity) (Narrative) (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Abs Cdo Portfolio [Member]	Sep. 30, 2014 Second Lien Residential Mortgage Backed Securities And Reserves [Member]	Sep. 30, 2014 First Lien Residential Mortgage Backed Securities [Member]	Sep. 30, 2014 Financial Guarantee [Member]	Dec. 31, 2013 Financial Guarantee [Member]	Sep. 30, 2014 Financial Guarantee [Member] Variable Interest Entity Primary Beneficiary [Member]	Dec. 31, 2013 Financial Guarantee [Member] Variable Interest Entity Primary Beneficiary [Member]	Sep. 30, 2014 Loss And Lae Reserves [Member]	Dec. 31, 2013 Loss And Lae Reserves [Member]	Sep. 30, 2014 Recoveries On Unpaid Losses [Member]	Dec. 31, 2013 Recoveries On Unpaid Losses [Member]	Sep. 30, 2014 Insurance Loss Recoverable [Member]	Dec. 31, 2013 Insurance Loss Recoverable [Member]	Sep. 30, 2014 Insurance Loss Recoverable [Member] Classified [Member]	Dec. 31, 2013 Insurance Loss Recoverable [Member] Classified [Member]	Sep. 30, 2014 Loan Repurchase Commitments [Member] Second Lien Residential Mortgage Backed Securities And Reserves [Member] Ineligible Loan Recoveries [Member]	Dec. 31, 2013 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]
ABS CDO exposure decrease since December 31,2007					97.00%
Aggregate ABS CDO Loss And LAE Reserves								$ 72,000,000	$ 115,000,000	$ 243,000,000	$ 226,000,000
Policyholder (Benefits) And Claims Incurred Net	20,000,000	98,000,000	82,000,000	92,000,000	(14,000,000)	88,000,000	39,000,000
Elimination Of Loss And LAE Expense (Benefit) As Result Of Consolidating VIE					17,000,000	25,000,000	(1,000,000)
Reserves for expected future claim payments												612,000,000	847,000,000
Expected recoveries of future payments												95,000,000	206,000,000	95,000,000	206,000,000
Weighted average risk-free rate used to discount claim liability			2.01%
Total estimated insurance recoveries																				365,000,000	359,000,000
Insurance claim loss recoverable																		568,000,000	694,000,000
Insurance loss recoverable																575,000,000	694,000,000	575,000,000	694,000,000
Losses and LAE related to expected payments			$ (56,000,000)			$ 13,000,000	$ 43,000,000