Commercial Mortgage Residual Interests (Narrative And Schedule Of Key Assumptions Used In Determining The Value Of The Residuals) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Mortgage Loans On Real Estate [Line Items]
Discount rate	25.00%	25.00%
Loss severity of loans in foreclosure	20.00%	20.00%
LIBOR	Forward 3-month curve	Forward 3-month curve
Prime	Forward curve	Forward curve
Maximum [Member]
Mortgage Loans On Real Estate [Line Items]
Average Life Equivalent CPR Speeds Range	24.31%	18.57%
Foreclosures Frequency Curve Default Model	4.49%	4.70%
Minimum [Member]
Mortgage Loans On Real Estate [Line Items]
Average Life Equivalent CPR Speeds Range	0.80%	2.18%
Foreclosures Frequency Curve Default Model	0.10%	0.20%