Schedule VI. Supplemental Information Concerning Property-Casualty Insurance Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental Information For Property Casualty Insurance Underwriters [Abstract]
Deferred Policy Acquisition Costs	$ 19,300	$ 20,412	$ 19,649
Reserves for Unpaid Loss and Loss Adjustment Expense	742,776	718,033	687,602
Unearned Premium	162,028	167,983	168,576
Earned Premium	368,704	375,894	375,747
Net Investment Income	28,106	27,902	27,214
Loss and LAE Related to Current Period	250,337	262,387	268,633
Loss and LAE Related to Prior Periods	(51,306)	(47,814)	(23,717)
Amortization of Deferred Policy Acquisition Costs	(44,321)	(44,841)	(43,817)
Paid Claims and Claim Adjustment Expenses	187,686	189,666	182,506
Net Premiums Written	$ 362,748	$ 375,301	$ 380,026

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Amount of amortization expense on deferred policy acquisition cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-18)
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e575016-122915

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Amount, after effects of reinsurance, of expense for claims incurred in the current reporting period and related claims settlement costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-18)
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e575016-122915

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Amount of deferred policy acquisition cost related to property-casualty insurance policy written.

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Amount of property-casualty insurance premium revenue earned on insurance policies.

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Amount of net investment income earned by property-casualty insurance underwriter.

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Payments of claims and claims adjustment expenses during the period of a property-casualty insurance entity.

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Amount of actual premium written by property-casualty insurance underwriter.

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Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs.

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The amount of reserve, policy claim payable and loss expense incurred by property-casualty insurance underwriter.

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Amount of property-casualty insurance premium revenue not yet earned on insurance policies.

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