Investments - Amortized Cost and Fair Value of Fixed Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortized cost
Due in one year or less	$ 4,768	$ 16,934
Due after one year through five years	17,584	13,876
Due after five years through ten years	0	232
Amortized Cost, Total	22,352	31,042
Fair value
Due in one year or less	4,743	16,899
Due after one year through five years	17,394	13,708
Due after five years through ten years	0	241
Fair Value, Total	$ 22,137	$ 30,848