Loss And Loss Adjustment Expense Reserves (Schedule Of Losses And Loss Adjustment Expenses) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder Benefits And Claims Incurred Net	$ (6)		$ 50
U S Public Finance Insurance [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder Benefits And Claims Incurred Net	(6)		(14)
Second-Lien RMBS [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder Benefits And Claims Incurred Net	(8)		25
First-Lien RMBS [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder Benefits And Claims Incurred Net	9		30
Other [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Policyholder Benefits And Claims Incurred Net	$ (1)	[1]	$ 9	[1]

[1] Includes ABS CDOs, CMBS, non-U.S. public finance and other issues.