Investments, Securities with Continuous Unrealized Loss Position (Details) $ in Thousands	Sep. 30, 2023 USD ($) Securities	Dec. 31, 2022 USD ($) Securities
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	$ 24,783	$ 159,874
12 months or longer	171,806	33,773
Total	196,589	193,647
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	1,051	20,326
12 months or longer	33,585	8,464
Total	$ 34,636	$ 28,790
Number of securities in unrealized loss position | Securities	251	237
Allowance for expected credit losses on available-for-sale fixed maturities	$ 0	$ 0
U.S. Treasury Securities and Obligations of U.S. Government Agencies and Authorities [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	10,205	23,763
12 months or longer	36,873	19,259
Total	47,078	43,022
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	264	2,410
12 months or longer	6,331	3,516
Total	6,595	5,926
Allowance for expected credit losses on available-for-sale fixed maturities	0
Obligations of States and Political Subdivisions [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	2,121	8,183
12 months or longer	5,449	0
Total	7,570	8,183
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	39	1,702
12 months or longer	1,908	0
Total	1,947	1,702
Allowance for expected credit losses on available-for-sale fixed maturities	0
Corporate Securities [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	12,457	127,928
12 months or longer	129,484	14,514
Total	141,941	142,442
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	748	16,214
12 months or longer	25,346	4,948
Total	26,094	$ 21,162
Allowance for expected credit losses on available-for-sale fixed maturities	$ 0