Fair Value of Financial Instruments Significant Unobservable Inputs Level 3 (Details) (Fair Value, Inputs, Level 3 [Member])	12 Months Ended
	Dec. 31, 2012
Non-Agency CMBS [Member]
Fair Value Inputs, Quantitative Information [Abstract]
Fair Value Inputs, Prepayment Rate	20.00%	[1]
Fair Value Inputs, Probability of Default	2.50%	[1]
Fair Value Inputs, Loss Severity	35.00%	[1]
Fair Value Inputs, Discount Rate	4.30%	[1]
Non-Agency RMBS [Member]
Fair Value Inputs, Quantitative Information [Abstract]
Fair Value Inputs, Prepayment Rate	5.00%	[1]
Fair Value Inputs, Probability of Default	0.50%	[1]
Fair Value Inputs, Loss Severity	9.00%	[1]
Fair Value Inputs, Discount Rate	5.10%	[1]

[1] Data presented are weighted averages.