Loss And Loss Adjustment Expense Reserves (Schedule Of Losses And Loss Adjustment Expenses) (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Losses and LAE related to actual and expected payments			$ (38)
Recoveries of actual and expected payments			54
Gross losses incurred			16
Reinsurance			(2)
Losses and LAE	50	(73)	14	142
RMBS [Member]
Losses and LAE related to actual and expected payments			16
Recoveries of actual and expected payments			(66)
Gross losses incurred			(50)
Reinsurance			0
Losses and LAE			(50)
Non-RMBS [Member]
Losses and LAE related to actual and expected payments			(54)
Recoveries of actual and expected payments			120
Gross losses incurred			66
Reinsurance			(2)
Losses and LAE			$ 64