Financial Derivatives (Schedule of Credit Derivatives) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Credit Derivatives [Line Items]
Financial derivatives–assets, at fair value-		$ 18,894	$ 15,479
Derivative Liability		(12,298)	(24,553)
Derivative Assets (Liabilities), at Fair Value, Net		6,596	(9,074)
Credit default swaps on asset-backed indices
Credit Derivatives [Line Items]
Financial derivatives–assets, at fair value-		1,751	2,184
Derivative Liability		(39)	(130)
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Long
Credit Derivatives [Line Items]
Notional value		484	395
Financial derivatives–assets, at fair value-		$ 7	5
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Long | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	16 years 11 months 26 days	24 years 3 months 25 days
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Short
Credit Derivatives [Line Items]
Notional value		$ 13,947	12,888
Financial derivatives–assets, at fair value-		$ 1,744	2,179
Credit default swaps on asset-backed indices | Financial Derivatives - Assets | Short | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	39 years 7 months 9 days	42 years 5 months 4 days
Credit default swaps on asset-backed indices | Financial Derivatives - Liabilities | Long
Credit Derivatives [Line Items]
Notional value		$ 89	479
Derivative Liability		$ (39)	(130)
Credit default swaps on asset-backed indices | Financial Derivatives - Liabilities | Long | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	32 years 4 months 9 days	27 years 4 months 28 days
Credit default swaps on asset-backed indices | Financial Derivatives - Liabilities | Short
Credit Derivatives [Line Items]
Notional value		$ 491	1
Derivative Liability		$ 0	0
Credit default swaps on asset-backed indices | Financial Derivatives - Liabilities | Short | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	29 years	24 years 5 months 1 day
Credit default swaps on corporate bond indices
Credit Derivatives [Line Items]
Financial derivatives–assets, at fair value-		$ 156	3,420
Derivative Liability		(1,870)	(6,438)
Credit default swaps on corporate bond indices | Financial Derivatives - Assets | Long
Credit Derivatives [Line Items]
Notional value		2,168	67,779
Financial derivatives–assets, at fair value-		$ 156	3,296
Credit default swaps on corporate bond indices | Financial Derivatives - Assets | Long | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	2 years 6 months 7 days	1 year 11 months 19 days
Credit default swaps on corporate bond indices | Financial Derivatives - Assets | Short
Credit Derivatives [Line Items]
Notional value		$ 0	2,173
Financial derivatives–assets, at fair value-		$ 0	124
Credit default swaps on corporate bond indices | Financial Derivatives - Assets | Short | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	2 years 11 months 19 days	0 days
Credit default swaps on corporate bond indices | Financial Derivatives - Liabilities | Short
Credit Derivatives [Line Items]
Notional value		$ 21,183	110,624
Derivative Liability		$ (1,870)	(6,438)
Credit default swaps on corporate bond indices | Financial Derivatives - Liabilities | Short | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	2 years 9 months 10 days	4 years 9 months
Credit default swaps on asset-backed securities
Credit Derivatives [Line Items]
Financial derivatives–assets, at fair value-		$ 303	347
Credit default swaps on asset-backed securities | Financial Derivatives - Assets | Short
Credit Derivatives [Line Items]
Notional value		910	957
Financial derivatives–assets, at fair value-		$ 303	347
Credit default swaps on asset-backed securities | Financial Derivatives - Assets | Short | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	14 years 8 months 12 days	13 years 8 months 15 days
Credit default swaps on corporate bonds
Credit Derivatives [Line Items]
Derivative Liability		$ (99)	(747)
Credit default swaps on corporate bonds | Financial Derivatives - Liabilities | Short
Credit Derivatives [Line Items]
Notional value		3,400	8,400
Derivative Liability		$ (99)	(747)
Credit default swaps on corporate bonds | Financial Derivatives - Liabilities | Short | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	4 years 2 months 1 day	3 years 5 months 19 days
Credit default swaps
Credit Derivatives [Line Items]
Notional value		$ 37,190	66,390
Derivative Assets (Liabilities), at Fair Value, Net		$ 202	(1,364)
Credit default swaps | Weighted Average
Credit Derivatives [Line Items]
Remaining Years to Maturity	10 years 3 months	19 years 1 month 6 days
Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Fair Value		$ 124	3,171
Notional value		$ 2,741	$ 68,653