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

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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/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 17 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17) -URI http://asc.fasb.org/extlink&oid=6588446&loc=d3e574992-122915 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.1) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 1 -Article 7 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.13(c)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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