Investments - Summary of Gross Investment Gains and Losses before Applicable Income Taxes (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Gain (Loss) on Securities [Line Items]
Gross investment gains	$ 86,000	$ 3,290,000	$ 5,897,000	$ 6,428,000
Gross investment losses	1,656,000	22,000	757,000	7,368,000
Net investment (losses) gains	(1,570,476)	3,268,459	5,139,609	(940,488)
Fixed Maturities [Member]
Gain (Loss) on Securities [Line Items]
Gross investment gains	86,000	159,000	610,000	811,000
Gross investment losses	82,000	22,000	156,000	240,000
Equity Securities [Member]
Gain (Loss) on Securities [Line Items]
Gross investment gains	0	3,131,000	5,287,000	5,617,000
Gross investment losses	$ 1,574,000	$ 0	$ 601,000	$ 7,128,000