Segment Information - Summary of Financial Data by Segment (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Premiums earned
Net premiums earned	$ 142,149,561	$ 130,645,011	$ 412,286,978	$ 382,310,380
GAAP premiums earned	142,150,000	130,645,000	412,287,000	382,310,000
Net investment income	4,299,044	4,624,287	13,529,304	14,110,288
Realized investment gains	351,269	349,164	2,296,909	2,943,710
Equity in earnings of DFSC	476,906	735,380	1,234,773	2,499,854
Other	1,858,000	1,982,000	5,608,000	5,851,000
Total revenues	149,135,383	138,334,960	434,956,398	407,715,187
Underwriting income (loss):
SAP underwriting income (loss)	3,798,000	1,576,000	(14,336,000)	(6,318,000)
GAAP adjustments	730,000	1,509,000	7,130,000	5,849,000
GAAP underwriting income (loss)	4,528,000	3,085,000	(7,206,000)	(469,000)
Net investment income	4,299,044	4,624,287	13,529,304	14,110,288
Realized investment gains	351,269	349,164	2,296,909	2,943,710
Equity in earnings of DFSC	476,906	735,380	1,234,773	2,499,854
Other	959,000	721,000	2,286,000	1,375,000
Income before income tax expense	10,613,824	9,514,208	12,140,520	20,459,655
Commercial Lines [Member]
Premiums earned
Net premiums earned	59,221,000	52,040,000	170,263,000	149,283,000
Underwriting income (loss):
GAAP underwriting income (loss)	2,383,000	2,537,000	(8,792,000)	(2,133,000)
Personal Lines [Member]
Premiums earned
Net premiums earned	82,929,000	78,605,000	242,024,000	233,027,000
Underwriting income (loss):
GAAP underwriting income (loss)	$ 1,415,000	$ (961,000)	$ (5,544,000)	$ (4,185,000)