Investments - Summary of Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	$ 167,231	$ 128,614
Equity securities, Cost or Amortized Cost	47,750	47,548
Total available-for-sale securities, Cost or Amortized Cost	214,981	176,162
Total available-for-sale securities, Gross Unrealized Gain	1,422	1,896
Total available-for-sale securities, Gross Unrealized Gain	5,769	2,139
Total available-for-sale securities, Gross Unrealized Gain	7,191	4,035
Total available-for-sale securities, Gross Unrealized Loss	(2,405)	(5,501)
Total available-for-sale securities, Gross Unrealized Loss	(484)	(1,450)
Total available-for-sale securities, Gross Unrealized Loss	(2,889)	(6,951)
Fixed-maturity securities, Estimated Fair Value	166,248	125,009
Equity securities, Estimated Fair Value	53,035	48,237
Total available-for-sale securities, Estimated Fair Value	219,283	173,246
Fixed-Maturity Securities [Member] | U.S. Treasury and U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	1,975	108
Total available-for-sale securities, Gross Unrealized Gain		5
Total available-for-sale securities, Gross Unrealized Loss	(36)
Fixed-maturity securities, Estimated Fair Value	1,939	113
Fixed-Maturity Securities [Member] | Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	75,538	42,560
Total available-for-sale securities, Gross Unrealized Gain	607	74
Total available-for-sale securities, Gross Unrealized Loss	(1,641)	(4,815)
Fixed-maturity securities, Estimated Fair Value	74,504	37,819
Fixed-Maturity Securities [Member] | State, Municipalities, and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	78,018	75,812
Total available-for-sale securities, Gross Unrealized Gain	776	1,632
Total available-for-sale securities, Gross Unrealized Loss	(488)	(120)
Fixed-maturity securities, Estimated Fair Value	78,306	77,324
Fixed-Maturity Securities [Member] | Exchange-Traded Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	11,463	9,817
Total available-for-sale securities, Gross Unrealized Gain	36	177
Total available-for-sale securities, Gross Unrealized Loss	(237)	(565)
Fixed-maturity securities, Estimated Fair Value	11,262	9,429
Fixed-Maturity Securities [Member] | Redeemable Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities, Cost or Amortized Cost	237	317
Total available-for-sale securities, Gross Unrealized Gain	3	8
Total available-for-sale securities, Gross Unrealized Loss	(3)	(1)
Fixed-maturity securities, Estimated Fair Value	$ 237	$ 324