Investments and Related Income - Summary of Net Investment Income (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross, Investment Income	$ 2,347	$ 2,267
Investment expense	(146)	(160)
Net investment income	2,201	2,107
Fixed Maturities
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross, Investment Income	1,835	1,869
Equity Securities
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross, Investment Income	31	37
Real Estate Investment
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross, Investment Income	26	37
Cash and Cash Equivalents
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross, Investment Income	153	8
Policy Loans
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross, Investment Income	174	176
Other Long-term Investments
Schedule Of Investment Income Reported Amounts By Category [Line Items]
Gross, Investment Income	$ 128	$ 140

Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.2)
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Amount after accretion (amortization) of discount (premium), and investment expense, of interest income and dividend income on nonoperating securities.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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-Subparagraph (SX 210.5-03.7(a),(b))
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-Name Accounting Standards Codification
-Topic 220
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