Valuation (Schedule Of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014		Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	$ 57,560	[1]	$ 59,664	[1]
Fair value repurchase agreements	29,875	[1]	27,962	[1]
Investments sold short, at fair value-	(818,765)		(845,614)
Financial derivatives–liabilities, at fair value-	(29,504)	[1]	(44,791)	[1]
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	170,362		183,489
Total investments and financial derivatives–assets, at fair value and repurchase agreements	65		0
Total investments sold short, financial derivatives–liabilities, and securitized debt, at fair value	(7,045)		(8,742)
Level 1 [Member] | Investments Sold Short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	(6,903)		(6,369)
Level 1 [Member] | Investments Sold Short [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	0		0
Level 1 [Member] | Investments Sold Short [Member] | Government debt sold short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	0		0
Level 1 [Member] | Investments Sold Short [Member] | Common Stock Sold Short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	(6,903)		(6,369)
Level 1 [Member] | Financial Derivatives - Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(142)		(2,373)
Level 1 [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Liabilities [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Liabilities [Member] | Put Option [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Liabilities [Member] | Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(142)		(2,373)
Level 1 [Member] | Financial Derivatives - Liabilities [Member] | Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 1 [Member] | Securitized Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securitized debt	0		0
Level 1 [Member] | Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 1 [Member] | Investments [Member] | Private Label Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 1 [Member] | Investments [Member] | Private Label Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 1 [Member] | Investments [Member] | Commercial Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 1 [Member] | Investments [Member] | Residential Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 1 [Member] | Investments [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 1 [Member] | Investments [Member] | Residential Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0
Level 1 [Member] | Investments [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	65		0
Level 1 [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Assets [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Assets [Member] | Put Option [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 1 [Member] | Financial Derivatives - Assets [Member] | Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	65
Level 1 [Member] | Financial Derivatives - Assets [Member] | Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0
Level 1 [Member] | Repurchase Agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value repurchase agreements	0		0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0		0
Total investments and financial derivatives–assets, at fair value and repurchase agreements	1,148,978		1,060,822
Total investments sold short, financial derivatives–liabilities, and securitized debt, at fair value	(840,874)		(881,313)
Level 2 [Member] | Investments Sold Short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	(811,862)		(839,245)
Level 2 [Member] | Investments Sold Short [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	(787,667)		(811,957)
Level 2 [Member] | Investments Sold Short [Member] | Government debt sold short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	(24,195)		(27,288)
Level 2 [Member] | Investments Sold Short [Member] | Common Stock Sold Short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	0		0
Level 2 [Member] | Financial Derivatives - Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(29,012)		(42,068)
Level 2 [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(7,095)		(11,866)
Level 2 [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 2 [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(15,984)		(24,949)
Level 2 [Member] | Financial Derivatives - Liabilities [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(5,532)		(5,064)
Level 2 [Member] | Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(31)		(67)
Level 2 [Member] | Financial Derivatives - Liabilities [Member] | Put Option [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(328)		(84)
Level 2 [Member] | Financial Derivatives - Liabilities [Member] | Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 2 [Member] | Financial Derivatives - Liabilities [Member] | Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(42)		(38)
Level 2 [Member] | Securitized Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securitized debt	0		0
Level 2 [Member] | Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	1,076,782		989,842
Level 2 [Member] | Investments [Member] | Private Label Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 2 [Member] | Investments [Member] | Private Label Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 2 [Member] | Investments [Member] | Commercial Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 2 [Member] | Investments [Member] | Residential Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 2 [Member] | Investments [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0		0
Level 2 [Member] | Investments [Member] | Residential Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	0
Level 2 [Member] | Investments [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	1,076,782		989,842
Level 2 [Member] | Financial Derivatives - Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	42,321		43,018
Level 2 [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	5,097		4,937
Level 2 [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 2 [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	19,176		14,273
Level 2 [Member] | Financial Derivatives - Assets [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	17,473		23,553
Level 2 [Member] | Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	15		4
Level 2 [Member] | Financial Derivatives - Assets [Member] | Put Option [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	393		251
Level 2 [Member] | Financial Derivatives - Assets [Member] | Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0
Level 2 [Member] | Financial Derivatives - Assets [Member] | Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	167
Level 2 [Member] | Repurchase Agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value repurchase agreements	29,875		27,962
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0		0
Total investments and financial derivatives–assets, at fair value and repurchase agreements	694,403		756,934
Total investments sold short, financial derivatives–liabilities, and securitized debt, at fair value	(1,333)		(1,333)
Level 3 [Member] | Investments Sold Short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	0		0
Level 3 [Member] | Investments Sold Short [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	0		0
Level 3 [Member] | Investments Sold Short [Member] | Government debt sold short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	0		0
Level 3 [Member] | Investments Sold Short [Member] | Common Stock Sold Short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(350)		(350)
Level 3 [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(350)		(350)
Level 3 [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Liabilities [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Liabilities [Member] | Put Option [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Liabilities [Member] | Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Liabilities [Member] | Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	0		0
Level 3 [Member] | Securitized Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securitized debt	(983)		(983)
Level 3 [Member] | Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	679,229		740,288
Level 3 [Member] | Investments [Member] | Private Label Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	490,083		580,772
Level 3 [Member] | Investments [Member] | Private Label Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	32,645		32,994
Level 3 [Member] | Investments [Member] | Commercial Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	44,005		23,887
Level 3 [Member] | Investments [Member] | Residential Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	23,566		24,062
Level 3 [Member] | Investments [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	47,458		38,069
Level 3 [Member] | Investments [Member] | Residential Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	97
Level 3 [Member] | Investments [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	41,375		40,504
Level 3 [Member] | Financial Derivatives - Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	15,174		16,646
Level 3 [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	15,174		16,646
Level 3 [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Assets [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Assets [Member] | Put Option [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0		0
Level 3 [Member] | Financial Derivatives - Assets [Member] | Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0
Level 3 [Member] | Financial Derivatives - Assets [Member] | Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	0
Level 3 [Member] | Repurchase Agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value repurchase agreements	0		0
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	170,362		183,489
Total investments and financial derivatives–assets, at fair value and repurchase agreements	1,843,446		1,817,756
Total investments sold short, financial derivatives–liabilities, and securitized debt, at fair value	(849,252)		(891,388)
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments Sold Short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	(818,765)		(845,614)
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments Sold Short [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	(787,667)		(811,957)
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments Sold Short [Member] | Government debt sold short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	(24,195)		(27,288)
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments Sold Short [Member] | Common Stock Sold Short [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments sold short, at fair value-	(6,903)		(6,369)
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(29,504)		(44,791)
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(7,095)		(11,866)
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(350)		(350)
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Liabilities [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(15,984)		(24,949)
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Liabilities [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(5,532)		(5,064)
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Liabilities [Member] | Total Return Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(31)		(67)
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Liabilities [Member] | Put Option [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(328)		(84)
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Liabilities [Member] | Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(142)		(2,373)
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Liabilities [Member] | Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–liabilities, at fair value-	(42)		(38)
Estimate of Fair Value, Fair Value Disclosure [Member] | Securitized Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securitized debt	(983)		(983)
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	1,756,011		1,730,130
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments [Member] | Private Label Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	490,083		580,772
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments [Member] | Private Label Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	32,645		32,994
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments [Member] | Commercial Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	44,005		23,887
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments [Member] | Residential Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	23,566		24,062
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	47,458		38,069
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments [Member] | Residential Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	97
Estimate of Fair Value, Fair Value Disclosure [Member] | Investments [Member] | Agency residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, at fair value-	1,118,157		1,030,346
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	57,560		59,664
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	5,097		4,937
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Asset Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	15,174		16,646
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Assets [Member] | Credit Default Swaps On Corporate Bond Indices [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	19,176		14,273
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Assets [Member] | Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	17,473		23,553
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Assets [Member] | Total Return Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	15		4
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Assets [Member] | Put Option [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	393		251
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Assets [Member] | Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	65
Estimate of Fair Value, Fair Value Disclosure [Member] | Financial Derivatives - Assets [Member] | Forwards [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives–assets, at fair value-	167
Estimate of Fair Value, Fair Value Disclosure [Member] | Repurchase Agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value repurchase agreements	29,875		27,962
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers of financial instruments between Level 1, Level 2, or Level 3	$ 0		$ 0

[1] In the Company's Consolidated Statement of Assets, Liabilities, and Equity, all balances associated with repurchase agreements, reverse repurchase agreements, and financial derivatives are presented on a gross basis.