Loss And Loss Adjustment Expense Reserves (Loss And LAE Activity) (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	$ 94	$ 22
Weighted average risk-free rate used to discount claim liability	2.14%
Insurance loss recoverable	$ 486		$ 504
Loss and loss adjustment expense reserves	559		541
Reinsurance Receivables Case Basis	6		6
Second Lien Residential Mortgage Backed Securities And Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	23	12
Lae [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder (Benefits) And Claims Incurred Net	12	$ 8
Loss and loss adjustment expense reserves	62		$ 60
Ineligible Mortgage Loans [Member] | Second Lien Residential Mortgage Backed Securities And Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Contract Claims On Ineligible Mortgage Loans Inception To Date Incurred Loss On Transactions	$ 440