Financial Derivatives (Credit Default Swaps) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Financial derivatives–assets, at fair value-	$ 198,023	$ 132,518
Financial derivatives–liabilities, at fair value-	(38,520)	(54,198)
Fair Value	(159,503)	(78,320)
Credit default swaps on asset-backed indices
Derivative [Line Items]
Financial derivatives–assets, at fair value-	3,574	3,366
Financial derivatives–liabilities, at fair value-	(33)	(33)
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Short
Derivative [Line Items]
Notional Amount	(42,770)	(58,004)
Financial derivatives–assets, at fair value-	$ 3,562	$ 3,362
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Short | Weighted Average
Derivative [Line Items]
Remaining Years to Maturity	35 years 3 months 25 days	35 years 8 months 12 days
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Long
Derivative [Line Items]
Notional Amount	$ (234)	$ (253)
Financial derivatives–assets, at fair value-	$ 12	$ 4
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Long | Weighted Average
Derivative [Line Items]
Remaining Years to Maturity	14 years 3 months	14 years 11 months 26 days
Credit default swaps on asset-backed securities
Derivative [Line Items]
Financial derivatives–assets, at fair value-	$ 76	$ 76
Credit default swaps on asset-backed securities | Financial Derivatives - Assets | Short
Derivative [Line Items]
Notional Amount	(220)	(220)
Financial derivatives–assets, at fair value-	$ 76	$ 76
Credit default swaps on asset-backed securities | Financial Derivatives - Assets | Short | Weighted Average
Derivative [Line Items]
Remaining Years to Maturity	11 years 10 months 9 days	12 years 7 months 9 days
Credit default swaps
Derivative [Line Items]
Notional Amount	$ (626,491)	$ (238,773)
Fair Value	$ 3,244	$ (1,720)
Credit default swaps | Weighted Average
Derivative [Line Items]
Remaining Years to Maturity	7 years 2 months 23 days	12 years 4 months 6 days
Credit default swaps on corporate bond indices
Derivative [Line Items]
Financial derivatives–assets, at fair value-	$ 2,298	$ 83
Financial derivatives–liabilities, at fair value-	(8,891)	(1,513)
Credit default swaps on corporate bond indices | Financial Derivatives - Assets | Short
Derivative [Line Items]
Notional Amount	0	(1,498)
Financial derivatives–assets, at fair value-	$ 0	$ 43
Remaining Years to Maturity	0 days	11 months 19 days
Credit default swaps on corporate bond indices | Financial Derivatives - Assets | Long
Derivative [Line Items]
Notional Amount	$ (148,953)	$ (2,037)
Financial derivatives–assets, at fair value-	$ 2,298	$ 40
Credit default swaps on corporate bond indices | Financial Derivatives - Assets | Long | Weighted Average
Derivative [Line Items]
Remaining Years to Maturity	4 years 8 months 1 day	11 months 19 days
Credit default swaps on corporate bonds
Derivative [Line Items]
Financial derivatives–liabilities, at fair value-	$ (268)	$ (259)
Credit default swaps on corporate bonds | Financial Derivatives - Assets | Long
Derivative [Line Items]
Notional Amount	(31)	0
Financial derivatives–assets, at fair value-	$ 0	$ 0
Credit default swaps on corporate bonds | Financial Derivatives - Assets | Long | Weighted Average
Derivative [Line Items]
Remaining Years to Maturity	2 months 19 days	0 days