Loss And Loss Adjustment Expense Reserves (Schedule Of Total Estimated Recoveries From Ineligible Second-Lien Mortgage Loans) (Detail) (Ineligible Mortgage Loans [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Ineligible Mortgage Loans [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Total Estimated Recoveries from Ineligible Mortgage Loans, Beginning Balance	$ 3,583
Accretion of Future Collections	11
Changes in Discount Rates	(1)
Recoveries (Collections)
Changes in Amount of Collections
Changes in Assumptions	374
Total Estimated Recoveries from Ineligible Mortgage Loans, Ending Balance	$ 3,967