Investments - Summary of Gross Realized Gains and Losses from Investments before Applicable Income Taxes (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gain (Loss) on Securities [Line Items]
Gross gains	$ 2,022,422	$ 6,366,108	$ 3,539,656
Gross losses	6,823,931	660,853	1,014,081
Net (losses) gains	(4,801,509)	5,705,255	2,525,575
Change in difference between fair value and cost of investments	(24,143,286)	3,905,577	(9,772,114)
Fixed Maturities [Member]
Gain (Loss) on Securities [Line Items]
Gross gains	131,660	168,855	2,161,108
Gross losses	630,904	98,723	281,131
Change in difference between fair value and cost of investments	(20,641,433)	2,335,578	(12,932,470)
Equity Securities [Member]
Gain (Loss) on Securities [Line Items]
Gross gains	1,890,762	6,197,253	1,378,548
Gross losses	6,193,027	562,130	732,950
Change in difference between fair value and cost of investments	$ (3,501,853)	$ 1,569,999	$ 3,160,356