Investments in Securities and Fair Value Investments in Securities (Schedule of Fair Value Assets Measured on Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	$ 53,989	$ 79,791
Equity securities, at fair value (cost: December 31, 2022: $25,278; December 31, 2021: $29,478)	51,691	76,853
Money market funds and US treasury bills	103,649	45,930
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	4,322	0
Equity securities, at fair value (cost: December 31, 2022: $25,278; December 31, 2021: $29,478)	51,691	76,853
Money market funds and US treasury bills	103,649	45,930
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	49,667	79,791
Equity securities, at fair value (cost: December 31, 2022: $25,278; December 31, 2021: $29,478)	0	0
Money market funds and US treasury bills	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	0	0
Equity securities, at fair value (cost: December 31, 2022: $25,278; December 31, 2021: $29,478)	0	0
Money market funds and US treasury bills	0	0
General obligations of U.S. states, territories and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	42,878	61,795
General obligations of U.S. states, territories and political subdivisions | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	4,322	0
General obligations of U.S. states, territories and political subdivisions | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	38,556	61,795
General obligations of U.S. states, territories and political subdivisions | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	0	0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	11,111	17,996
Corporate debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	0	0
Corporate debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	11,111	17,996
Corporate debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, available-for-sale, at fair value	$ 0	$ 0