Investments - Amortized Cost and Fair Value of Fixed Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Amortized Cost
Due in one year or less	$ 11,441	$ 5,551
Due after one year through five years	16,859	22,757
Due after five years	330	330
Amortized Cost, Total	28,630	28,638
Fair Value
Due in one year or less	11,432	5,554
Due after one year through five years	16,813	22,708
Due after five years	341	340
Fair Value, Total	$ 28,586	$ 28,602