Investments - Amortized Cost and Fair Value of Fixed Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Amortized Cost
Due in one year or less	$ 5,551	$ 5,726
Due after one year through five years	22,757	12,038
Due after five years through ten years	330	330
Amortized Cost, Total	28,638	18,094
Fair Value
Due in one year or less	5,554	5,722
Due after one year through five years	22,708	12,041
Due after five years through ten years	340	329
Fair Value, Total	$ 28,602	$ 18,092