Loss And Loss Adjustment Expense Reserves (Schedule Of Losses And Loss Adjustment Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Loss And Loss Adjustment Expense Reserves [Line Items]
Losses and LAE related to actual and expected payments	$ 230
Recoveries of actual and expected payments	(308)
Gross losses incurred	(78)
Reinsurance	(2)
Second-Lien RMBS [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Losses and LAE related to actual and expected payments	163
Recoveries of actual and expected payments	(380)
Gross losses incurred	(217)
Reinsurance	0
Other Loss And LAE [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Losses and LAE related to actual and expected payments	67
Recoveries of actual and expected payments	72
Gross losses incurred	139
Reinsurance	$ (2)