Loss And Loss Adjustment Expense Reserves (RMBS Recoveries) (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Loss And Loss Adjustment Expense Reserves [Line Items]
Federal statutory rate	35.00%	35.00%	35.00%
Estimated insurance recoveries, after income taxes	$ 233	$ 2,300
Percentage of recognized estimated recoveries in relationship to consolidated total shareholder's equity	7.00%	73.00%
Remaining weighted average contract period (in years)	9 years 8 months 12 days	8 years 8 months 12 days