Investments - Summary of Fixed Maturities and Equity Securities with Unrealized Losses (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 174,277,178	$ 332,842,702
Less Than 12 Months, Unrealized Losses	1,756,291	7,069,063
More Than 12 Months, Fair Value	203,736,737	5,834,053
More Than 12 Months, Unrealized Losses	4,955,013	483,582
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	24,024,445	37,729,947
Less Than 12 Months, Unrealized Losses	286,518	1,279,510
More Than 12 Months, Fair Value	33,987,229
More Than 12 Months, Unrealized Losses	990,759
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	10,223,383	40,739,099
Less Than 12 Months, Unrealized Losses	120,076	802,311
More Than 12 Months, Fair Value	14,127,415	710,280
More Than 12 Months, Unrealized Losses	294,557	8,936
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	35,203,959	80,181,238
Less Than 12 Months, Unrealized Losses	253,241	2,127,451
More Than 12 Months, Fair Value	31,560,591	4,706,945
More Than 12 Months, Unrealized Losses	1,003,047	472,044
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	100,533,516	168,771,543
Less Than 12 Months, Unrealized Losses	817,315	2,727,720
More Than 12 Months, Fair Value	124,061,502	416,828
More Than 12 Months, Unrealized Losses	2,666,650	2,602
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	4,291,875	5,420,875
Less Than 12 Months, Unrealized Losses	$ 279,141	$ 132,071