Investments - Summary of Amortized Cost and Estimated Fair Values of Fixed Maturities and Equity Securities (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Total held to maturity, Amortized Cost	$ 402,798,518	$ 366,655,077
Held to Maturity, Gross Unrealized Gains	8,872,223	15,341,893
Held to Maturity, Gross Unrealized Losses	6,632,445	1,546,542
Total held to maturity, Estimated Fair Value	405,038,296	380,450,428
Available for Sale, Amortized Cost	535,112,451	538,414,337
Available for Sale, Gross Unrealized Gains	2,139,728	5,417,334
Available for Sale, Gross Unrealized Losses	10,693,875	4,885,621
Available for Sale, Estimated Fair Value	526,558,304	538,946,050
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Equity Method Investments [Line Items]
Total held to maturity, Amortized Cost	76,222,306	71,736,445
Held to Maturity, Gross Unrealized Gains	174,904	804,012
Held to Maturity, Gross Unrealized Losses	1,086,613	546,868
Total held to maturity, Estimated Fair Value	75,310,597	71,993,589
Available for Sale, Amortized Cost	45,188,053	44,759,456
Available for Sale, Gross Unrealized Gains	25,241	20,377
Available for Sale, Gross Unrealized Losses	1,003,365	730,409
Available for Sale, Estimated Fair Value	44,209,929	44,049,424
Obligations of States and Political Subdivisions [Member]
Schedule of Equity Method Investments [Line Items]
Total held to maturity, Amortized Cost	159,292,158	137,581,155
Held to Maturity, Gross Unrealized Gains	8,236,804	11,161,650
Held to Maturity, Gross Unrealized Losses	704,104	112,193
Total held to maturity, Estimated Fair Value	166,824,858	148,630,612
Available for Sale, Amortized Cost	73,760,836	128,478,000
Available for Sale, Gross Unrealized Gains	1,762,127	3,941,610
Available for Sale, Gross Unrealized Losses	306,994	302,440
Available for Sale, Estimated Fair Value	75,215,969	132,117,170
Corporate Securities [Member]
Schedule of Equity Method Investments [Line Items]
Total held to maturity, Amortized Cost	127,010,071	108,024,776
Held to Maturity, Gross Unrealized Gains	396,197	2,860,255
Held to Maturity, Gross Unrealized Losses	4,391,451	730,843
Total held to maturity, Estimated Fair Value	123,014,817	110,154,188
Available for Sale, Amortized Cost	140,688,937	105,254,120
Available for Sale, Gross Unrealized Gains	203,393	1,010,744
Available for Sale, Gross Unrealized Losses	3,059,185	525,445
Available for Sale, Estimated Fair Value	137,833,145	105,739,419
Mortgage-Backed Securities [Member]
Schedule of Equity Method Investments [Line Items]
Total held to maturity, Amortized Cost	40,273,983	49,312,701
Held to Maturity, Gross Unrealized Gains	64,318	515,976
Held to Maturity, Gross Unrealized Losses	450,277	156,638
Total held to maturity, Estimated Fair Value	39,888,024	49,672,039
Available for Sale, Amortized Cost	275,474,625	259,922,761
Available for Sale, Gross Unrealized Gains	148,967	444,603
Available for Sale, Gross Unrealized Losses	6,324,331	3,327,327
Available for Sale, Estimated Fair Value	$ 269,299,261	$ 257,040,037

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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