Financial Derivatives (Credit Default Swaps) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Financial derivatives–assets, at fair value-	$ 23,082	$ 15,479
Financial derivatives–liabilities, at fair value-	(19,438)	(24,553)
Fair Value	(3,644)	9,074
Credit default swaps on asset-backed indices
Derivative [Line Items]
Financial derivatives–assets, at fair value-	2,087	2,184
Financial derivatives–liabilities, at fair value-	(127)	(130)
Credit default swaps on asset-backed indices | Financial Derivatives - Liabilities | Short
Derivative [Line Items]
Notional Amount	(1)	(1)
Financial derivatives–liabilities, at fair value-	0	0
Credit default swaps on asset-backed securities
Derivative [Line Items]
Financial derivatives–assets, at fair value-	320	347
Credit default swaps
Derivative [Line Items]
Notional Amount	(50,134)	(66,390)
Fair Value	103	1,364
Credit default swaps on corporate bond indices
Derivative [Line Items]
Financial derivatives–assets, at fair value-	3,427	3,420
Financial derivatives–liabilities, at fair value-	(5,128)	(6,438)
Credit default swaps on corporate bond indices | Financial Derivatives - Liabilities | Short
Derivative [Line Items]
Notional Amount	(93,661)	(110,624)
Financial derivatives–liabilities, at fair value-	$ (5,128)	$ (6,438)