Valuation (Schedule Of Significant Unobservable Inputs, Qualitative Information) (Details) (USD $) In Thousands, unless otherwise specified							6 Months Ended				6 Months Ended				6 Months Ended				6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Level 3 [Member]	Dec. 31, 2011 Level 3 [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Residential Mortgage Backed Securities And Securitized Debt [Member]		Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Residential Mortgage Backed Securities And Securitized Debt [Member] Minimum [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Residential Mortgage Backed Securities And Securitized Debt [Member] Maximum [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Residential Mortgage Backed Securities And Securitized Debt [Member] Weighted Average [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Credit Default Swaps On Asset Backed Securities [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Credit Default Swaps On Asset Backed Securities [Member] Minimum [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Credit Default Swaps On Asset Backed Securities [Member] Maximum [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Credit Default Swaps On Asset Backed Securities [Member] Weighted Average [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Commercial Mortgage-Backed Securities And Commercial Mortgage Loans [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Commercial Mortgage-Backed Securities And Commercial Mortgage Loans [Member] Minimum [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Commercial Mortgage-Backed Securities And Commercial Mortgage Loans [Member] Maximum [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Private Label Commercial Mortgage-Backed Securities And Commercial Mortgage Loans [Member] Weighted Average [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Agency Interest Only Residential Mortgage-Backed Securities [Member]	Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Agency Interest Only Residential Mortgage-Backed Securities [Member] Minimum [Member]		Jun. 30, 2012 Level 3 [Member] Income Approach Valuation Technique [Member] Agency Interest Only Residential Mortgage-Backed Securities [Member] Maximum [Member]		Jun. 30, 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	$ 1,242,294	$ 1,331,104	$ 461,540	$ 504,861	$ 383,644	[1]				$ 38,759				$ 33,055				$ 4,667
Yield							4.20%	37.70%	9.30%						(25.50%)	13.00%	7.70%
Projected Collateral Prepayments							0.60%	42.50%	15.70%		5.60%	36.20%	13.50%						83.50%		94.30%		87.50%
Projected Collateral Losses							4.00%	87.90%	36.60%		25.20%	62.30%	48.60%		0.00%	28.20%	5.70%
Projected Collateral Recoveries							0.00%	41.60%	21.00%		11.50%	37.90%	19.40%		0.00%	42.30%	16.80%
Projected Collateral Scheduled Amortization							3.50%	89.80%	26.70%		8.60%	37.30%	18.50%		50.50%	100.00%	77.50%		5.70%		16.50%		12.50%
Total Outstanding Collateral									100.00%				100.00%				100.00%						100.00%
LIBOR OAS																			7.23%	[2]	27.19%	[2]	11.73%	[2]
Securitized debt	$ 1,415	$ 0

[1] Includes securitized debt with a fair value of $1.4 million as of June 30, 2012.

[2] Shown in basis points.