Investments - Gross Unrealized Gains and Losses and Cost or Amortized Cost and Fair Value of Investments Classified as Available-for-Sale (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	$ 473,315	$ 461,236
Fixed maturity, Gross Unrealized Gains	2,377	7,072
Fixed maturity, Gross Unrealized Losses	(7,673)	(2,714)
Fixed maturity, Fair Value	468,019	465,594
Equity securities, Cost or Amortized Cost	14,532	8,503
Equity securities, Gross Unrealized Gains		779
Equity securities, Fair Value	14,791	9,282
Totals, Cost or Amortized Cost		469,739
Totals, Gross Unrealized Gains		7,851
Totals, Gross Unrealized Losses		(2,714)
Totals, Fair Value		474,876
States and Political Subdivisions [Member]
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	229,007	244,898
Fixed maturity, Gross Unrealized Gains	2,334	6,819
Fixed maturity, Gross Unrealized Losses	(3,854)	(577)
Fixed maturity, Fair Value	227,487	251,140
Corporate Bonds [Member]
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	163,834	130,210
Fixed maturity, Gross Unrealized Gains	43	224
Fixed maturity, Gross Unrealized Losses	(929)	(212)
Fixed maturity, Fair Value	162,948	130,222
U.S. Agency-Based Mortgage-Backed Securities [Member]
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	13,256	18,813
Fixed maturity, Gross Unrealized Losses	(476)	(799)
Fixed maturity, Fair Value	12,780	18,014
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	67,218	67,315
Fixed maturity, Gross Unrealized Gains		29
Fixed maturity, Gross Unrealized Losses	(2,414)	(1,126)
Fixed maturity, Fair Value	$ 64,804	$ 66,218

Available for sale securities debt securities and equity securities Fv-Ni.

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Available for sale securities debt securities and equity Securities fair value net income accumulated gross unrealized gain before tax.

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Available for sale securities debt securities and equity Securities fair value net income accumulated gross unrealized loss before tax.

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Available for sale securities debt securities and equity securities fvni amortized cost basis.

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- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.

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