Valuation (Schedule Of Significant Unobservable Inputs, Qualitative Information) (Details) (USD $) In Thousands, unless otherwise specified							12 Months Ended				12 Months Ended				12 Months Ended				12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Level 3 [Member]	Dec. 31, 2011 Level 3 [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Residential Mortgage Backed Securities And Securitized Debt [Member]		Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Residential Mortgage Backed Securities And Securitized Debt [Member] Minimum [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Residential Mortgage Backed Securities And Securitized Debt [Member] Maximum [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Residential Mortgage Backed Securities And Securitized Debt [Member] Weighted Average [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Credit Default Swaps On Asset Backed Securities [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Credit Default Swaps On Asset Backed Securities [Member] Minimum [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Credit Default Swaps On Asset Backed Securities [Member] Maximum [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Credit Default Swaps On Asset Backed Securities [Member] Weighted Average [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Commercial Mortgage-Backed Securities And Commercial Mortgage Loans [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Commercial Mortgage-Backed Securities And Commercial Mortgage Loans [Member] Minimum [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Commercial Mortgage-Backed Securities And Commercial Mortgage Loans [Member] Maximum [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Commercial Mortgage-Backed Securities And Commercial Mortgage Loans [Member] Weighted Average [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Agency Interest Only Residential Mortgage-Backed Securities [Member]	Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Agency Interest Only Residential Mortgage-Backed Securities [Member] Minimum [Member]		Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Agency Interest Only Residential Mortgage-Backed Securities [Member] Maximum [Member]		Dec. 31, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Agency Interest Only Residential Mortgage-Backed Securities [Member] Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value			$ 599,914	$ 504,861	$ 527,031	[1]				$ 36,030				$ 28,873				$ 6,644
Yield							2.60%	29.10%	7.80%						5.20%	17.90%	9.50%
Projected Collateral Prepayments							0.70%	64.60%	22.70%		8.70%	44.10%	18.70%						81.00%		100.00%		92.70%
Projected Collateral Losses							3.70%	79.70%	28.00%		20.40%	57.10%	37.80%		0.00%	25.10%	3.90%
Projected Collateral Recoveries							0.00%	41.00%	21.40%		12.20%	32.80%	19.30%		0.00%	88.90%	20.50%
Projected Collateral Scheduled Amortization							4.10%	90.40%	27.90%		9.80%	35.50%	24.20%		0.00%	100.00%	75.60%		0.00%	[2]	19.00%	[2]	7.30%	[2]
LIBOR OAS																			8.16%	[3]	75.58%	[3]	11.89%	[3]
Total Outstanding Collateral									100.00%				100.00%				100.00%						100.00%
Securitized debt	$ 1,335	$ 0

[1] Includes securitized debt with a fair value of $1.3 million as of December 31, 2012.

[2] For simplicity of presentation, net negative amortization is disregarded.

[3] Shown in basis points.