Segment Information - Summary of Financial Data by Segment (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Premiums earned:
Premiums earned	$ 181,764,580	$ 169,156,147
Net investment income	6,378,369	5,755,399
Realized investment (losses) gains	(918,339)	2,548,975
Equity in earnings of DFSC	632,114	232,950
Other	1,471,000	1,278,000
Total revenues	189,328,278	178,970,963
Underwriting (loss) income:
SAP underwriting income (loss)	(37,477,000)	(5,157,000)
GAAP adjustments	2,368,000	2,873,000
GAAP underwriting loss	(35,109,000)	(2,284,000)
Net investment income	6,378,369	5,755,399
Realized investment (losses) gains	(918,339)	2,548,975
Equity in earnings of DFSC	632,114	232,950
Other	482,000	472,000
(Loss) income before income tax (benefit) expense	(28,535,171)	6,724,829
Commercial Lines [Member]
Premiums earned:
Premiums earned	82,226,000	76,619,000
Underwriting (loss) income:
SAP underwriting income (loss)	(20,210,000)	334,000
Personal Lines [Member]
Premiums earned:
Premiums earned	99,539,000	92,537,000
Underwriting (loss) income:
SAP underwriting income (loss)	$ (17,267,000)	$ (5,491,000)