Concentration of Operations - Net Premiums Earned for the Top Ten States (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 74,702	$ 74,771	$ 75,964	$ 78,990	$ 82,277	$ 82,712	$ 82,951	$ 84,948	$ 304,427	$ 332,888	$ 350,326
Premium earned percentage									100.00%	100.00%	100.00%
Florida [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 34,617	$ 39,936	$ 39,672
Premium earned percentage									11.40%	12.00%	11.30%
Georgia [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 37,926	$ 38,090	$ 40,351
Premium earned percentage									12.50%	11.40%	11.50%
Pennsylvania [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 24,340	$ 27,519	$ 31,708
Premium earned percentage									8.00%	8.30%	9.10%
Louisiana [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 22,668	$ 24,782	$ 25,810
Premium earned percentage									7.40%	7.40%	7.40%
North Carolina [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 17,338	$ 18,800	$ 19,537
Premium earned percentage									5.70%	5.70%	5.60%
Illinois [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 14,802	$ 16,929	$ 19,710
Premium earned percentage									4.90%	5.10%	5.60%
Virginia [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 14,041	$ 15,249	$ 15,228
Premium earned percentage									4.60%	4.60%	4.30%
Minnesota [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 11,057	$ 13,399	$ 12,900
Premium earned percentage									3.60%	4.00%	3.70%
Wisconsin [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 12,263	$ 13,388	$ 14,101
Premium earned percentage									4.00%	4.00%	4.00%
South Carolina [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 11,270	$ 13,020	$ 13,924
Premium earned percentage									3.70%	3.90%	4.00%
All Others [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned									$ 104,105	$ 111,776	$ 117,385
Premium earned percentage									34.20%	33.60%	33.50%