Investments - Summary of Amortized Cost and Estimated Fair Value of Fixed Maturities by Contractual Maturity (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Held to maturity
Due in one year or less, Amortized Cost	$ 16,132,891
Due after one year through five years, Amortized Cost	73,727,277
Due after five years through ten years, Amortized Cost	182,428,771
Due after ten years, Amortized Cost	171,659,600
Mortgage-backed securities, Amortized Cost	32,145,243
Total held to maturity, Amortized Cost	476,093,782	$ 402,798,518
Available for sale
Due in one year or less, Amortized Cost	12,943,726
Due after one year through five years, Amortized Cost	89,684,400
Due after five years through ten years, Amortized Cost	112,308,452
Due after ten years, Amortized Cost	14,474,110
Mortgage-backed securities, Amortized Cost	327,428,590
Total available for sale, Amortized Cost	556,839,278	535,112,451
Held to maturity
Due in one year or less, Estimated Fair Value	16,205,362
Due after one year through five years, Estimated Fair Value	76,542,800
Due after five years through ten years, Estimated Fair Value	191,642,042
Due after ten years, Estimated Fair Value	183,183,313
Mortgage-backed securities, Estimated Fair Value	32,740,827
Total held to maturity, Estimated Fair Value	500,314,344	405,038,296
Available for sale
Due in one year or less, Estimated Fair Value	13,075,792
Due after one year through five years, Estimated Fair Value	91,992,458
Due after five years through ten years, Estimated Fair Value	115,407,525
Due after ten years, Estimated Fair Value	14,928,281
Mortgage-backed securities, Estimated Fair Value	329,547,747
Total available for sale, Estimated Fair Value	$ 564,951,803	$ 526,558,304