Concentration of Operations - Net Premiums Earned for the Top Ten States (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned	$ 86,695	$ 81,596	$ 81,983	$ 79,709	$ 78,741	$ 72,425	$ 69,733	$ 69,790	$ 329,983	$ 290,689	$ 251,015
Premium earned percentage									100.00%	100.00%	100.00%
Louisiana [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									42,110	31,134	28,157
Premium earned percentage									12.80%	10.70%	11.20%
Georgia [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									30,096	25,033	21,496
Premium earned percentage									9.10%	8.60%	8.60%
Pennsylvania [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									28,880	24,480	19,265
Premium earned percentage									8.80%	8.40%	7.70%
North Carolina [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									21,019	20,036	17,071
Premium earned percentage									6.40%	6.90%	6.80%
Illinois [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									18,445	18,119	14,673
Premium earned percentage									5.60%	6.20%	5.80%
Oklahoma [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									17,473	16,157	16,037
Premium earned percentage									5.30%	5.60%	6.40%
Virginia [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									15,751	16,144	15,660
Premium earned percentage									4.80%	5.60%	6.20%
Texas [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									14,949	11,687	11,073
Premium earned percentage									4.50%	4.00%	4.40%
Florida [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									12,950	9,180	6,881
Premium earned percentage									3.90%	3.20%	2.80%
Alaska [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									12,239	9,202	8,618
Premium earned percentage									3.70%	3.20%	3.40%
All Others [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Premiums earned									$ 116,071	$ 109,517	$ 92,084
Premium earned percentage									35.10%	37.60%	36.70%