Loss And Loss Adjustment Expense Reserves (RMBS Reserves) (Narrative) (Details) (USD $)	1 Months Ended	6 Months Ended
	May 31, 2011	Dec. 31, 2011	Jun. 30, 2011
Percentage of loans in delinquent bucket	10.00%
Percentage of loans charged off	30.00%
Percentage of current roll to loss for transaction	3.00%
Decrease in percentage of current roll to loss for transaction	25.00%	0.75%
Percentage of further reduction of current roll to loss for transaction			0.00%
ALT-A [Member] | RMBS And ALT-A [Member]
Assumed percent of loss severity			100.00%
Percentage of loss before declining			25.00%
RMBS [Member]
Delinquency period for fully charged-off loans, days			90
Recoveries of actual and expected payments			$ 154,000,000
RMBS And HELOC And CES [Member]
Charged-off loan recovery value			0
Assumed roll rate for ninety plus day delinquent loans			100.00%
Roll rate percentage for additional stress test			97.00%
Period of elevated delinquency and loss, beginning, months			6
Current roll to loss percentage as a percent of prior month roll to loss percentage			25.00%
Period of elevated delinquency and loss for stress case, additional months			6
Increase to case basis reserves			$ 175,000,000