Investments - Fair Value and Gross Unrealized Losses of Investments, Available-for-Sale, by the Length of Time (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value	$ 86,000	$ 49,884
Less than 12 months, Gross Unrealized Losses	(3,079)	(1,191)
12 months or longer, Fair value		7,689
12 months or longer, Gross Unrealized Losses		(241)
Total Gross Unrealized Losses	(3,079)	(1,432)
Total Fixed Maturities, Available-for-Sale
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value	84,585	41,045
Less than 12 months, Gross Unrealized Losses	(2,968)	(529)
12 months or longer, Fair value		7,689
12 months or longer, Gross Unrealized Losses		(241)
Total Gross Unrealized Losses	(2,968)	(770)
Mutual Fund, Available-for-Sale
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value		8,839
Less than 12 months, Gross Unrealized Losses		(662)
Total Gross Unrealized Losses		(662)
U.S. Government and Agencies
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value	14,837	8,946
Less than 12 months, Gross Unrealized Losses	(303)	(85)
Total Gross Unrealized Losses	(303)	(85)
Political Subdivisions
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value	4,166
Less than 12 months, Gross Unrealized Losses	(68)
Total Gross Unrealized Losses	(68)
Revenue and Assessment
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value	2,783	1,733
Less than 12 months, Gross Unrealized Losses	(41)	(21)
Total Gross Unrealized Losses	(41)	(21)
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value	41,057	30,172
Less than 12 months, Gross Unrealized Losses	(1,805)	(422)
12 months or longer, Fair value		7,689
12 months or longer, Gross Unrealized Losses		(241)
Total Gross Unrealized Losses	(1,805)	(663)
Agency Backed
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value	21,637
Less than 12 months, Gross Unrealized Losses	(744)
Total Gross Unrealized Losses	(744)
Non-Agency Backed - Residential
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value	105	5
Less than 12 months, Gross Unrealized Losses	(7)	(1)
Total Gross Unrealized Losses	(7)	(1)
Collateralized mortgage obligations: Non-agency backed - commercial
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value		$ 189
Preferred Stock, available-for-sale
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair value	1,415
Less than 12 months, Gross Unrealized Losses	(111)
Total Gross Unrealized Losses	$ (111)