Loss And Loss Adjustment Expense Reserves (Schedule Of Losses And Loss Adjustment Expenses) (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Loss And Loss Adjustment Expense Reserves [Line Items]
Losses and LAE related to actual and expected payments			$ 255
Recoveries of actual and expected payments			(49)
Gross losses incurred			206
Reinsurance			(2)
Losses and LAE	190	(20)	204	122
Second-Lien RMBS [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Losses and LAE related to actual and expected payments			157
Recoveries of actual and expected payments			(122)
Gross losses incurred			35
Reinsurance			0
Losses and LAE			35
Other [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Losses and LAE related to actual and expected payments			98
Recoveries of actual and expected payments			73
Gross losses incurred			171
Reinsurance			(2)
Losses and LAE			$ 169