Segment Information - Summary of Financial Data by Segment (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Premiums earned
Net premiums earned	$ 169,156,147	$ 158,475,279
GAAP premiums earned	169,156,000	158,475,000
Net investment income	5,755,399	5,546,509
Realized investment gains	2,548,975	470,941
Equity in earnings of DFSC	232,950	35,227
Other	1,278,000	1,541,000
Total revenues	178,970,963	166,068,776
Underwriting (loss) income:
SAP underwriting (loss) income	(5,157,000)	7,515,000
GAAP adjustments	2,873,000	1,956,000
GAAP underwriting (loss) income	(2,284,000)	9,471,000
Net investment income	5,755,399	5,546,509
Realized investment gains	2,548,975	470,941
Equity in earnings of DFSC	232,950	35,227
Other	472,000	495,000
Income before income tax expense	6,724,829	16,018,539
Commercial Lines [Member]
Premiums earned
Net premiums earned	76,619,000	69,872,000
Underwriting (loss) income:
SAP underwriting (loss) income	334,000	4,840,000
Personal Lines [Member]
Premiums earned
Net premiums earned	92,537,000	88,603,000
Underwriting (loss) income:
SAP underwriting (loss) income	$ (5,491,000)	$ 2,675,000