Investments, Amortized Cost and Estimated Fair Value of Fixed Maturities by Contractual Maturity (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Held To Maturity [Abstract]
Due in one year or less, amortized cost	$ 22,133,000
Due after one year through five years, amortized cost	106,022,000
Due after five years through ten years, amortized cost	251,366,000
Due after ten years, amortized cost	295,877,000
Mortgage-backed securities, amortized cost	9,873,000
Held to maturity, amortized cost	685,271,000
Available For Sale [Abstract]
Due in one year or less, amortized cost	40,101,000
Due after one year through five years, amortized cost	175,077,000
Due after five years through ten years, amortized cost	102,498,000
Due after ten years, amortized cost	25,456,000
Mortgage-backed securities, amortized cost	285,619,000
Total available for sale, amortized cost	628,751,000	$ 571,913,000
Held To Maturity [Abstract]
Due in one year or less, estimated fair value	22,012,000
Due after one year through five years, estimated fair value	98,950,000
Due after five years through ten years, estimated fair value	217,144,000
Due after ten years, estimated fair value	225,272,000
Mortgage-backed securities, estimated fair value	9,125,000
Total held to maturity, estimated fair value	572,503,000	598,045,000
Available For Sale [Abstract]
Due in one year or less, estimated fair value	39,458,000
Due after one year through five years, estimated fair value	161,274,000
Due after five years through ten years, estimated fair value	89,399,000
Due after ten years, estimated fair value	20,589,000
Mortgage-backed securities, estimated fair value	255,820,000
Total available for sale, estimated fair value	$ 566,539,622	$ 523,791,931