Segment Information - Summary of Financial Data by Segment (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Premiums earned:
Premiums earned	$ 189,821,058	$ 187,661,705	$ 566,657,613	$ 555,140,395
Net investment income	7,389,749	6,620,491	21,727,904	19,341,012
Investment (losses) gains	(369,041)	3,463,504	19,294,229	4,062,475
Equity in earnings of DFSC		732,768	295,000	2,152,738
Other	1,168,000	1,426,000	3,538,000	4,326,000
Total revenues	198,009,900	199,904,180	611,512,728	585,022,486
Underwriting income (loss):
SAP underwriting income (loss)	(791,000)	(10,085,000)	(5,131,000)	(60,293,000)
GAAP adjustments	(399,000)	332,000	1,431,000	5,106,000
GAAP underwriting income (loss)	(1,190,000)	(9,753,000)	(3,700,000)	(55,187,000)
Net investment income	7,389,749	6,620,491	21,727,904	19,341,012
Investment (losses) gains	(369,041)	3,463,504	19,294,229	4,062,475
Equity in earnings of DFSC		732,768	295,000	2,152,738
Other	474,000	213,000	1,070,000	1,040,000
Income (loss) before income tax expense (benefit)	6,304,884	1,276,986	38,687,439	(28,591,231)
Commercial Lines [Member]
Premiums earned:
Premiums earned	98,324,000	84,251,000	284,593,000	251,029,000
Underwriting income (loss):
SAP underwriting income (loss)	2,521,000	2,125,000	4,946,000	(17,935,000)
Personal Lines [Member]
Premiums earned:
Premiums earned	91,497,000	103,410,000	282,065,000	304,111,000
Underwriting income (loss):
SAP underwriting income (loss)	$ (3,312,000)	$ (12,210,000)	$ (10,077,000)	$ (42,358,000)