Schedule of Investment Income (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Securities, Available-for-sale [Line Items]
Investment income	$ 12,162	$ 12,442	$ 34,712	$ 36,254
Investment expense	(814)	(692)	(2,319)	(2,146)
Net investment income	11,348	11,750	32,393	34,108
Fixed Maturities
Debt Securities, Available-for-sale [Line Items]
Investment income	8,806	9,520	27,692	27,236
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Investment income	1,704	1,006	4,384	3,010
Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Investment income	372	285	1,242	814
Other Invested Assets
Debt Securities, Available-for-sale [Line Items]
Investment income	$ 1,280	$ 1,631	$ 1,394	$ 5,194

Amount before accretion (amortization) of purchase discount (premium) of interest income and dividend income on nonoperating securities.

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-Publisher FASB
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-Topic 220
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Aggregate amount of net income allocated to limited partners.

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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
-Publisher FASB
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-Topic 944
-SubTopic 220
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