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

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- Definition

Amount of expenses related to the generation of investment income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
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-Topic 944
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-Section S99
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Amount, after 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.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(2))
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Investments - Major Categories of the Company's Net Investment Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investment [Line Items]
Total gross investment income									$ 31,418	$ 30,383	$ 29,753
Investment expenses									(966)	(1,102)	(1,647)
Net investment income	$ 8,056	$ 7,884	$ 7,303	$ 7,209	$ 7,312	$ 7,788	$ 7,471	$ 6,710	30,452	29,281	28,106
Fixed Maturity Securities Available for Sale [Member]
Investment [Line Items]
Total gross investment income									28,762	28,961	27,837
Equity Securities [Member]
Investment [Line Items]
Total gross investment income									448	201
Short-term Investments [Member]
Investment [Line Items]
Total gross investment income									$ 2,208	1,117	348
Other Investments [Member]
Investment [Line Items]
Total gross investment income										$ 104	$ 1,568