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Loss and Loss Adjustment Expenses - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Unpaid Losses And Loss Expenses [Line Items] |  |  |
Loss and LAE Related to Prior Periods | $ 63,484 | $ 65,002 | $ 45,596
Minimum period of underwriting workers’ compensation insurance from which historical loss data utilize | 35 years |  |
Accident Year 2017 [Member] |  |  |
Unpaid Losses And Loss Expenses [Line Items] |  |  |
Loss and LAE Related to Prior Periods | $ 14,500 |  |
Accident Year 2018 [Member] |  |  |
Unpaid Losses And Loss Expenses [Line Items] |  |  |
Loss and LAE Related to Prior Periods | $ 14,800 |  |

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- Definition Unpaid Losses And Loss Expenses [Line Items] + References No definition available. + Details
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- Definition Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437 + Details
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