Segment Information - Summary of Financial Data by Segment (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Premiums earned:
Premiums earned	$ 188,073,242	$ 181,764,580
Net investment income	7,048,503	6,378,369
Investment gains (losses)	18,097,113	(918,339)
Equity in earnings of DFSC	295,000	632,114
Other	1,200,000	1,471,000
Total revenues	214,713,874	189,328,278
Underwriting income (loss):
SAP underwriting income (loss)	785,000	(37,477,000)
GAAP adjustments	551,000	2,368,000
GAAP underwriting income (loss)	1,336,000	(35,109,000)
Net investment income	7,048,503	6,378,369
Investment gains (losses)	18,097,113	(918,339)
Equity in earnings of DFSC	295,000	632,114
Other	68,000	482,000
Income (loss) before income tax expense (benefit)	26,845,024	(28,535,171)
Commercial Lines [Member]
Premiums earned:
Premiums earned	91,481,000	82,226,000
Underwriting income (loss):
SAP underwriting income (loss)	(1,688,000)	(20,210,000)
Personal Lines [Member]
Premiums earned:
Premiums earned	96,592,000	99,539,000
Underwriting income (loss):
SAP underwriting income (loss)	$ 2,473,000	$ (17,267,000)