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	Jun. 30, 2018	Dec. 31, 2017
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	$ 443,358	$ 461,236
Fixed maturity, Gross Unrealized Gains	3,428	7,072
Fixed maturity, Gross Unrealized Losses	(6,024)	(2,714)
Fixed maturity, Fair Value	440,762	465,594
Equity securities, Cost or Amortized Cost	13,590	8,503
Equity securities, Gross Unrealized Gains		779
Equity securities, Gross Unrealized Losses
Equity securities, Fair Value	13,590	9,282
Totals, Cost or Amortized Cost	456,948	469,739
Totals, Gross Unrealized Gains	3,428	7,851
Totals, Gross Unrealized Losses	(6,024)	(2,714)
Totals, Fair Value	454,352	474,876
States and Political Subdivisions [Member]
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	217,427	244,898
Fixed maturity, Gross Unrealized Gains	3,368	6,819
Fixed maturity, Gross Unrealized Losses	(2,495)	(577)
Fixed maturity, Fair Value	218,300	251,140
Corporate Bonds [Member]
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	144,950	130,210
Fixed maturity, Gross Unrealized Gains	60	224
Fixed maturity, Gross Unrealized Losses	(1,051)	(212)
Fixed maturity, Fair Value	143,959	130,222
U.S. Agency-Based Mortgage-Backed Securities [Member]
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	13,730	18,813
Fixed maturity, Gross Unrealized Losses	(368)	(799)
Fixed maturity, Fair Value	13,362	18,014
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Investment [Line Items]
Fixed maturity, Cost or Amortized Cost	67,251	67,315
Fixed maturity, Gross Unrealized Gains		29
Fixed maturity, Gross Unrealized Losses	(2,110)	(1,126)
Fixed maturity, Fair Value	$ 65,141	$ 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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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).

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