Concentration of Operations - Net Premiums Earned for the Top Ten States (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 275,993	$ 304,427	$ 332,888
Premium earned percentage	100.00%	100.00%	100.00%
Florida [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 31,514	$ 34,617	$ 39,936
Premium earned percentage	11.40%	11.40%	12.00%
Georgia [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 34,772	$ 37,926	$ 38,090
Premium earned percentage	12.60%	12.50%	11.40%
Pennsylvania [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 19,574	$ 24,340	$ 27,519
Premium earned percentage	7.10%	8.00%	8.30%
Louisiana [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 20,476	$ 22,668	$ 24,782
Premium earned percentage	7.40%	7.40%	7.40%
North Carolina [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 15,964	$ 17,338	$ 18,800
Premium earned percentage	5.80%	5.70%	5.70%
Illinois [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 13,680	$ 14,802	$ 16,929
Premium earned percentage	5.00%	4.90%	5.10%
Virginia [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 12,579	$ 14,041	$ 15,249
Premium earned percentage	4.60%	4.60%	4.60%
Minnesota [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 10,612	$ 11,057	$ 13,399
Premium earned percentage	3.80%	3.60%	4.00%
Wisconsin [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 13,108	$ 12,263	$ 13,388
Premium earned percentage	4.70%	4.00%	4.00%
South Carolina [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 9,186	$ 11,270	$ 13,020
Premium earned percentage	3.30%	3.70%	3.90%
All Others [Member]
Schedule Of Premiums Earned Net By Segment [Line Items]
Net premiums earned	$ 94,528	$ 104,105	$ 111,776
Premium earned percentage	34.30%	34.20%	33.60%