Net Investment Income (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Investment Income [Line Items]
Investment Income	$ 25,436	$ 23,166	$ 49,826	$ 45,503
Investment Expenses	(835)	(901)	(1,523)	(1,790)
Net Investment Income	24,601	22,265	48,303	43,713
Fixed Maturities
Net Investment Income [Line Items]
Investment Income	21,719	19,186	42,771	37,527
Equity Securities
Net Investment Income [Line Items]
Investment Income	3,161	3,780	6,086	7,564
Short-Term Investments, Cash & Cash Equivalents
Net Investment Income [Line Items]
Investment Income	415	87	642	170
Other Invested Assets
Net Investment Income [Line Items]
Investment Income	$ 141	$ 113	$ 327	$ 242

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.

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-SubTopic 220
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Amount of expenses related to the generation of investment income.

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-Publisher FASB
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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.

+ References

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