Concentration of Operations - Net Premiums Earned for the Top Ten States (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 82,277	$ 82,712	$ 82,951	$ 84,948	$ 88,837	$ 85,184	$ 88,995	$ 87,310	$ 332,888	$ 350,326	$ 346,156
Premium earned percentage									100.00%	100.00%	100.00%
Florida [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 39,936	$ 39,672	$ 34,615
Premium earned percentage									12.00%	11.30%	10.00%
Georgia [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 38,090	$ 40,351	$ 40,801
Premium earned percentage									11.40%	11.50%	11.80%
Pennsylvania [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 27,519	$ 31,708	$ 32,931
Premium earned percentage									8.30%	9.10%	9.50%
Louisiana [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 24,782	$ 25,810	$ 25,422
Premium earned percentage									7.40%	7.40%	7.30%
North Carolina [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 18,800	$ 19,537	$ 18,388
Premium earned percentage									5.70%	5.60%	5.30%
Illinois [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 16,929	$ 19,710	$ 22,169
Premium earned percentage									5.10%	5.60%	6.40%
Virginia [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 15,249	$ 15,228	$ 16,298
Premium earned percentage									4.60%	4.30%	4.70%
Minnesota [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 13,399	$ 12,900	$ 13,968
Premium earned percentage									4.00%	3.70%	4.00%
Wisconsin [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 13,388	$ 14,101	$ 13,790
Premium earned percentage									4.00%	4.00%	4.00%
South Carolina [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 13,020	$ 13,924	$ 13,327
Premium earned percentage									3.90%	4.00%	3.90%
All Others [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 111,776	$ 117,385	$ 114,447
Premium earned percentage									33.60%	33.50%	33.10%