Segment Information - Summary of Financial Data by Segment (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:
Net premiums earned	$ 130,645,011	$ 120,916,960	$ 382,310,380	$ 353,177,873
GAAP adjustments				(5,000)
GAAP premiums earned	130,645,000	120,917,000	382,310,000	353,178,000
Net investment income	4,624,287	4,715,295	14,110,288	14,724,305
Realized investment gains	349,164	1,312,137	2,943,710	5,150,450
Equity in earnings of DFSC	735,380	1,336,818	2,499,854	3,621,593
Other	1,982,000	2,151,000	5,851,000	6,405,000
Total revenues	138,334,960	130,431,531	407,715,187	383,078,883
Underwriting income (loss):
SAP underwriting income (loss)	1,576,000	(1,473,000)	(6,318,000)	(11,727,000)
GAAP adjustments	1,509,000	1,888,000	5,849,000	6,408,000
GAAP underwriting income (loss)	3,085,000	415,000	(469,000)	(5,319,000)
Net investment income	4,624,000	4,715,000	14,110,000	14,724,000
Realized investment gains	349,164	1,312,137	2,943,710	5,150,450
Equity in earnings of DFSC	735,380	1,336,818	2,499,854	3,621,593
Other	721,000	1,094,000	1,375,000	2,659,000
Income before income tax expense	9,514,208	8,872,682	20,459,655	20,835,498
Operating Segments [Member] | Commercial Lines [Member]
Revenues:
Net premiums earned	52,040,000	44,921,000	149,283,000	128,704,000
Underwriting income (loss):
GAAP underwriting income (loss)	2,537,000	2,507,000	(2,133,000)	4,827,000
Operating Segments [Member] | Personal Lines [Member]
Revenues:
Net premiums earned	78,605,000	75,996,000	233,027,000	224,479,000
Underwriting income (loss):
GAAP underwriting income (loss)	$ (961,000)	$ (3,980,000)	$ (4,185,000)	$ (16,554,000)