Loss And Loss Adjustment Expense Reserves (RMBS Reserves) (Narrative) (Details) (USD $)	0 Months Ended		6 Months Ended		12 Months Ended		6 Months Ended	12 Months Ended
	Nov. 30, 2011	Nov. 30, 2011	Jun. 30, 2012	May 31, 2012	Dec. 31, 2011	Dec. 31, 2011 RMBS [Member] days	May 31, 2012 RMBS And HELOC And CES [Member]	Nov. 30, 2012 RMBS And HELOC And CES [Member]	Dec. 31, 2011 RMBS And HELOC And CES [Member]	Dec. 31, 2011 Firstlien RMBS [Member]	Dec. 31, 2011 Commercial Mortgage Backed [Member]	Dec. 31, 2011 ALT-A [Member] RMBS And ALT-A [Member]	Dec. 31, 2011 Foreclosure [Member]	Dec. 31, 2011 Real Estate Owned [Member]	Dec. 31, 2011 Bankruptcy [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Charged-off loan recovery value					$ 0
Delinquency period for fully charged-off loans, days						90
Assumed roll rate for ninety plus day delinquent loans									95.00%
Assumed roll rate for loans													90.00%	90.00%	75.00%
Period of elevated delinquency and loss, beginning, months							6
Percentage of loans in 30-59 days delinquent		10.00%
90+ day roll rate to loss is set										90.00%
Percentage of loans charged off		30.00%
Percentage of current roll to loss for transaction	3.00%
Loan severities in certain instances exceded											100.00%
Decrease in percentage of current roll to loss for transaction			0.75%	25.00%			25.00%
Current roll to loss early 2014					0.00%
Period of elevated delinquency and loss for stress case, additional months								6
Increase to case basis reserves if losses remain at modeled peak levels									$ 120,000,000
Percentage of loss after declining over a 24 month period												25.00%