Valuation (Schedule Of Significant Unobservable Inputs, Qualitative Information) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Securitized debt	774,000		983,000
Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	638,486,000		756,934,000
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Residential Mortgage Backed Securities and Securitized Debt [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	201,373,000	[1]
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Residential Mortgage Backed Securities and Securitized Debt [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	1.83	[1]
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Residential Mortgage Backed Securities and Securitized Debt [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	119.58	[1]
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Residential Mortgage Backed Securities and Securitized Debt [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	73.58	[1]
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Residential Mortgage Backed Securities, Other Asset-backed securities And Securitized Debt [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value			550,701,000	[2]
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Residential Mortgage Backed Securities, Other Asset-backed securities And Securitized Debt [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation			1.80	[2]
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Residential Mortgage Backed Securities, Other Asset-backed securities And Securitized Debt [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation			110.35	[2]
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Residential Mortgage Backed Securities, Other Asset-backed securities And Securitized Debt [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation			78.09	[2]
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Commercial Mortgage Backed Securities And Commercial Mortgage Loans [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value			34,489,000
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Commercial Mortgage Backed Securities And Commercial Mortgage Loans [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation			14.25
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Commercial Mortgage Backed Securities And Commercial Mortgage Loans [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation			102.89
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Commercial Mortgage Backed Securities And Commercial Mortgage Loans [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation			74.24
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Commercial Mortgage-Backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	40,919,000
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Commercial Mortgage-Backed Securities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	5.62
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Commercial Mortgage-Backed Securities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	103.25
Level 3 [Member] | Market Approach Valuation Technique [Member] | Private Label Commercial Mortgage-Backed Securities [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	66.56
Level 3 [Member] | Market Approach Valuation Technique [Member] | Agency Interest Only Residential Mortgage-Backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	22,928,000		38,783,000
Level 3 [Member] | Market Approach Valuation Technique [Member] | Agency Interest Only Residential Mortgage-Backed Securities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	3.62		6.26
Level 3 [Member] | Market Approach Valuation Technique [Member] | Agency Interest Only Residential Mortgage-Backed Securities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	24.86		33.77
Level 3 [Member] | Market Approach Valuation Technique [Member] | Agency Interest Only Residential Mortgage-Backed Securities [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	11.38		14.53
Level 3 [Member] | Market Approach Valuation Technique [Member] | Other Asset-backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	123,029,000
Level 3 [Member] | Market Approach Valuation Technique [Member] | Other Asset-backed Securities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	21.50
Level 3 [Member] | Market Approach Valuation Technique [Member] | Other Asset-backed Securities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	137.00
Level 3 [Member] | Market Approach Valuation Technique [Member] | Other Asset-backed Securities [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	94.91
Level 3 [Member] | Income Approach Valuation Technique [Member] | Corporate debt, Non-exchange traded corporate equity, and warrants [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	45,668,000
Level 3 [Member] | Income Approach Valuation Technique [Member] | Corporate debt, Non-exchange traded corporate equity, and warrants [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	73.00
Yield	7.50%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Corporate debt, Non-exchange traded corporate equity, and warrants [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	108.00
Yield	24.30%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Corporate debt, Non-exchange traded corporate equity, and warrants [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non Binding Third-Party Valuation	95.08
Yield	13.30%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Private Label Residential Mortgage-Backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	72,222,000		67,158,000
Level 3 [Member] | Income Approach Valuation Technique [Member] | Private Label Residential Mortgage-Backed Securities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	3.00%		3.80%
Projected Collateral Prepayments	6.70%		6.90%
Projected Collateral Losses	0.00%		4.30%
Projected Collateral Recoveries	0.00%		0.30%
Projected Collateral Scheduled Amortization	0.00%		14.10%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Private Label Residential Mortgage-Backed Securities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	13.60%		20.50%
Projected Collateral Prepayments	100.00%		64.50%
Projected Collateral Losses	44.50%		35.20%
Projected Collateral Recoveries	22.40%		17.10%
Projected Collateral Scheduled Amortization	86.40%		87.30%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Private Label Residential Mortgage-Backed Securities [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	7.00%		8.00%
Projected Collateral Prepayments	45.60%		29.70%
Projected Collateral Losses	11.30%		17.40%
Projected Collateral Recoveries	8.00%		9.10%
Projected Collateral Scheduled Amortization	35.10%		43.80%
Total Outstanding Collateral	100.00%		100.00%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Private Label Commercial Mortgage-Backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	12,392,000		3,480,000
Level 3 [Member] | Income Approach Valuation Technique [Member] | Private Label Commercial Mortgage-Backed Securities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	12.00%		9.20%
Projected Collateral Losses	0.10%		0.20%
Projected Collateral Recoveries	0.90%		15.40%
Projected Collateral Scheduled Amortization	85.30%		84.40%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Private Label Commercial Mortgage-Backed Securities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	51.10%		18.20%
Projected Collateral Losses	2.50%		0.20%
Projected Collateral Recoveries	13.50%		15.40%
Projected Collateral Scheduled Amortization	99.00%		84.40%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Private Label Commercial Mortgage-Backed Securities [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	23.70%		13.50%
Projected Collateral Losses	0.70%		0.20%
Projected Collateral Recoveries	6.20%		15.40%
Projected Collateral Scheduled Amortization	93.10%		84.40%
Total Outstanding Collateral	100.00%		100.00%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Performing Commercial Mortgage Loans [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	21,328,000		8,788,000
Level 3 [Member] | Income Approach Valuation Technique [Member] | Performing Commercial Mortgage Loans [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	9.20%		12.70%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Performing Commercial Mortgage Loans [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	13.10%		12.80%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Performing Commercial Mortgage Loans [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	10.30%		12.70%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Non-performing Commercial Mortgage Loans [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	6,981,000		10,123,000
Level 3 [Member] | Income Approach Valuation Technique [Member] | Non-performing Commercial Mortgage Loans [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	15.30%		15.00%
Months to Resolution	0 months 15 days		5 months
Level 3 [Member] | Income Approach Valuation Technique [Member] | Non-performing Commercial Mortgage Loans [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	20.10%		15.00%
Months to Resolution	10 months 15 days		7 months
Level 3 [Member] | Income Approach Valuation Technique [Member] | Non-performing Commercial Mortgage Loans [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	16.40%		15.00%
Months to Resolution	8 months 6 days		6 months
Level 3 [Member] | Income Approach Valuation Technique [Member] | Agency Interest Only Residential Mortgage-Backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	8,457,000		1,721,000
Level 3 [Member] | Income Approach Valuation Technique [Member] | Agency Interest Only Residential Mortgage-Backed Securities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Projected Collateral Prepayments	50.20%		49.00%
Projected Collateral Scheduled Amortization	0.00%		41.90%
LIBOR OAS	1.54%	[3]	3.49%	[3]
Level 3 [Member] | Income Approach Valuation Technique [Member] | Agency Interest Only Residential Mortgage-Backed Securities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Projected Collateral Prepayments	100.00%		58.10%
Projected Collateral Scheduled Amortization	49.80%		51.00%
LIBOR OAS	17.96%	[3]	6.45%	[3]
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]
Projected Collateral Prepayments	75.50%		51.20%
Projected Collateral Scheduled Amortization	24.50%		48.80%
Total Outstanding Collateral	100.00%		100.00%
LIBOR OAS	3.59%	[3]	4.22%	[3]
Level 3 [Member] | Income Approach Valuation Technique [Member] | Residential Mortgage Loans and Real Estate Owned Properties [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	36,117,000
Level 3 [Member] | Income Approach Valuation Technique [Member] | Residential Mortgage Loans and Real Estate Owned Properties [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	6.10%
Months to Resolution	4 months 3 days
Level 3 [Member] | Income Approach Valuation Technique [Member] | Residential Mortgage Loans and Real Estate Owned Properties [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	12.00%
Months to Resolution	79 months 3 days
Level 3 [Member] | Income Approach Valuation Technique [Member] | Residential Mortgage Loans and Real Estate Owned Properties [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	7.30%
Months to Resolution	24 months 18 days
Level 3 [Member] | Income Approach Valuation Technique [Member] | Residential Mortgage Loans [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value			24,062,000
Level 3 [Member] | Income Approach Valuation Technique [Member] | Residential Mortgage Loans [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield			7.40%
Months to Resolution			16 months 9 days
Level 3 [Member] | Income Approach Valuation Technique [Member] | Residential Mortgage Loans [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield			7.40%
Months to Resolution			16 months 9 days
Level 3 [Member] | Income Approach Valuation Technique [Member] | Residential Mortgage Loans [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield			7.40%
Months to Resolution			16 months 9 days
Level 3 [Member] | Income Approach Valuation Technique [Member] | Other asset-backed securities and loans [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	23,259,000
Level 3 [Member] | Income Approach Valuation Technique [Member] | Other asset-backed securities and loans [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	0.00%
Projected Collateral Prepayments	62.70%
Projected Collateral Losses	4.00%
Projected Collateral Recoveries	1.70%
Projected Collateral Scheduled Amortization	31.60%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Other asset-backed securities and loans [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	14.40%
Projected Collateral Prepayments	62.70%
Projected Collateral Losses	4.00%
Projected Collateral Recoveries	1.70%
Projected Collateral Scheduled Amortization	31.60%
Level 3 [Member] | Income Approach Valuation Technique [Member] | Other asset-backed securities and loans [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	9.10%
Projected Collateral Prepayments	62.70%
Projected Collateral Losses	4.00%
Projected Collateral Recoveries	1.70%
Projected Collateral Scheduled Amortization	31.60%
Total Outstanding Collateral	100.00%
Credit Default Swaps On Asset Backed Securities [Member] | Level 3 [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	11,148,000		16,296,000
Credit Default Swaps On Asset Backed Securities [Member] | Level 3 [Member] | Income Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Projected Collateral Prepayments	17.80%		19.30%
Projected Collateral Losses	16.50%		15.50%
Projected Collateral Recoveries	7.70%		8.20%
Projected Collateral Scheduled Amortization	15.90%		15.70%
Credit Default Swaps On Asset Backed Securities [Member] | Level 3 [Member] | Income Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Projected Collateral Prepayments	55.80%		59.00%
Projected Collateral Losses	37.70%		47.80%
Projected Collateral Recoveries	18.50%		15.20%
Projected Collateral Scheduled Amortization	43.40%		41.20%
Credit Default Swaps On Asset Backed Securities [Member] | Level 3 [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Projected Collateral Prepayments	32.50%		29.90%
Projected Collateral Losses	29.70%		34.80%
Projected Collateral Recoveries	12.80%		13.10%
Projected Collateral Scheduled Amortization	25.00%		22.20%
Total Outstanding Collateral	100.00%		100.00%
Private Corporate Investments [Member] | Non-Exchange Traded Preferred Equity Investment in Commercial Mortgage-related Private Partnership | Level 3 [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	6,241,000
Private Corporate Investments [Member] | Non-Exchange Traded Preferred Equity Investment in Commercial Mortgage-related Private Partnership | Level 3 [Member] | Income Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	10.00%
Expected Holding Period (Months)	17 months
Private Corporate Investments [Member] | Non-Exchange Traded Preferred Equity Investment in Commercial Mortgage-related Private Partnership | Level 3 [Member] | Income Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	10.00%
Expected Holding Period (Months)	17 months
Private Corporate Investments [Member] | Non-Exchange Traded Preferred Equity Investment in Commercial Mortgage-related Private Partnership | Level 3 [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	10.00%
Expected Holding Period (Months)	17 months
Private Corporate Investments [Member] | Non-Exchange Traded Preferred and Common Equity Investment in Mortgage-Related Entities [Member] | Level 3 [Member] | Recent Transactions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	5,411,000

[1] Includes securitized debt with a fair value of $0.8 million as of December 31, 2014.

[2] Includes securitized debt with a fair value of $1.0 million as of December 31, 2013.

[3] Shown in basis points.