Financial Derivatives (Schedule of Credit Derivatives) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Credit Derivatives [Line Items]
Financial derivatives–assets, at fair value-	$ 198,023	$ 132,518
Derivative Liability	(38,520)	(54,198)
Derivative Assets (Liabilities), at Fair Value, Net	159,503	78,320
Credit default swaps on asset-backed indices
Credit Derivatives [Line Items]
Financial derivatives–assets, at fair value-	3,574	3,366
Derivative Liability	(33)	(33)
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Long
Credit Derivatives [Line Items]
Notional value	234	253
Financial derivatives–assets, at fair value-	$ 12	$ 4
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Long | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	14 years 3 months	14 years 11 months 26 days
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Short
Credit Derivatives [Line Items]
Notional value	$ 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
Credit Derivatives [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 - Liabilities | Long
Credit Derivatives [Line Items]
Notional value	$ 65	$ 65
Derivative Liability	$ (33)	$ (33)
Credit default swaps on asset-backed indices | Financial Derivatives - Liabilities | Long | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	25 years 8 months 23 days	26 years 5 months 23 days
Credit default swaps on corporate bond indices
Credit Derivatives [Line Items]
Financial derivatives–assets, at fair value-	$ 2,298	$ 83
Derivative Liability	(8,891)	(1,513)
Credit default swaps on corporate bond indices | Financial Derivatives - Assets | Long
Credit Derivatives [Line Items]
Notional value	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
Credit Derivatives [Line Items]
Remaining Years to Maturity	4 years 8 months 1 day	11 months 19 days
Credit default swaps on corporate bond indices | Financial Derivatives - Assets | Short
Credit Derivatives [Line Items]
Notional value	$ 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 - Liabilities | Short
Credit Derivatives [Line Items]
Notional value	$ 716,384	$ 165,006
Remaining Years to Maturity	5 years 1 month 9 days	4 years 11 months 8 days
Derivative Liability	$ (8,891)	$ (1,513)
Credit default swaps on asset-backed securities
Credit Derivatives [Line Items]
Financial derivatives–assets, at fair value-	76	76
Credit default swaps on asset-backed securities | Financial Derivatives - Assets | Short
Credit Derivatives [Line Items]
Notional value	220	220
Financial derivatives–assets, at fair value-	$ 76	$ 76
Credit default swaps on asset-backed securities | Financial Derivatives - Assets | Short | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	11 years 10 months 9 days	12 years 7 months 9 days
Credit default swaps on corporate bonds
Credit Derivatives [Line Items]
Derivative Liability	$ (268)	$ (259)
Credit default swaps on corporate bonds | Financial Derivatives - Assets | Long
Credit Derivatives [Line Items]
Notional value	31	0
Financial derivatives–assets, at fair value-	$ 0	$ 0
Credit default swaps on corporate bonds | Financial Derivatives - Assets | Long | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	2 months 19 days	0 days
Credit default swaps on corporate bonds | Financial Derivatives - Liabilities | Short
Credit Derivatives [Line Items]
Notional value	$ 16,400	$ 16,400
Derivative Liability	$ (268)	$ (259)
Credit default swaps on corporate bonds | Financial Derivatives - Liabilities | Short | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	3 years 3 months 21 days	4 years 21 days
Credit default swaps
Credit Derivatives [Line Items]
Notional value	$ 626,491	$ 238,773
Derivative Assets (Liabilities), at Fair Value, Net	$ (3,244)	$ 1,720
Credit default swaps | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	7 years 2 months 23 days	12 years 4 months 6 days
Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Fair Value	$ 2,277	$ 11
Notional value	$ 149,283	$ 2,355