Financial Derivatives (Fair Value of Financial Derivatives) (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-	[1]	$ 15,356	$ 20,001
Financial derivatives–liabilities, at fair value-	[1]	(26,904)	$ (20,806)
Total		(11,548)
TBA securities purchase contracts
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		445
Financial derivatives–liabilities, at fair value-		(33)
TBA securities sale contracts
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		86
Financial derivatives–liabilities, at fair value-		(3,042)
Fixed payer interest rate swaps
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		2,291
Financial derivatives–liabilities, at fair value-		(6,243)
Fixed receiver interest rate swaps
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		3,096
Financial derivatives–liabilities, at fair value-		(1,328)
Basis swaps
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		4
Credit default swaps on asset-backed securities
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		1,233
Financial derivatives–liabilities, at fair value-		(822)
Credit default swaps on asset-backed indices
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		3,276
Credit default swaps on corporate bonds
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		715
Financial derivatives–liabilities, at fair value-		(945)
Credit default swaps on corporate bond indices
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		3,519
Financial derivatives–liabilities, at fair value-		(11,907)
Recovery swaps
Derivatives, Fair Value [Line Items]
Financial derivatives–liabilities, at fair value-		(8)
Total return swaps
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		123
Futures
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		138
Financial derivatives–liabilities, at fair value-		(2,454)
Forwards
Derivatives, Fair Value [Line Items]
Financial derivatives–assets, at fair value-		430
Financial derivatives–liabilities, at fair value-		$ (122)

[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.