Investments - Schedule of Investments in Fixed Maturity Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, Single Maturity Date	$ 9,200	$ 9,500
Cost	28,630	28,638
Gross Unrealized Gains	20	24
Gross Unrealized Losses	(64)	(60)
Fair Value	28,586	28,602
U.S. Treasury securities, obligations of U.S. Government agencies and municipals
Schedule of Available-for-sale Securities [Line Items]
Cost	26,648	26,280
Gross Unrealized Gains	6	11
Gross Unrealized Losses	(64)	(59)
Fair Value	26,590	26,232
Corporate debt
Schedule of Available-for-sale Securities [Line Items]
Cost	1,982	2,358
Gross Unrealized Gains	14	13
Gross Unrealized Losses	0	(1)
Fair Value	$ 1,996	$ 2,370