Commitments and Contingencies - Additional Information (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Line Items]
Accrued guaranty fund	$ 3,800,000	$ 3,300,000
Estimated future of premium tax deductions	3,400,000
Amount of deposit with governmental authorities required by law	8,400,000	8,600,000
Derivative cash collateral received	1,000,000	300,000
Assets pledged as collateral	513,200,000	538,700,000
Mortgage Backed Securities
Commitments and Contingencies Disclosure [Line Items]
Funds pledged on mortgage loans held investment portfolio	$ 4,800,000	$ 8,500,000

Assets Pledged As Collateral

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- Definition

Commitments and Contingencies Disclosure [Line Items]

+ References

No definition available.

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- Definition

Carrying amount of cash and investment securities on deposit with state regulatory authorities in connection with capital requirements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 825
-Section 50
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=75763970&loc=SL75763979-209797

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Fair value of securities received as collateral against derivative assets.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 12
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This item represents a non-contingent liability for the fair value of an obligation to stand ready to perform over the term of a guaranty issued in the event that specified triggering events or conditions occur.

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-Name Accounting Standards Codification
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-SubTopic 210
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Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

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-Publisher FASB
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The amount of insurance-related assessment liability that is expected to be recovered through a premium tax offset based on current laws applied to in-force policies.

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