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Concentration of Operations - Net Premiums Earned for the Top Ten States (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
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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%

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- Definition Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums earned. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(1)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17(Column E)) -URI http://asc.fasb.org/extlink&oid=120401096&loc=d3e574992-122915 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(c)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
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