Investment Securities - Schedule of Amortized Cost and Estimated Fair Value of Fixed-Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Investments Debt And Equity Securities [Abstract]
Amortized Cost, 2016	$ 74,767
Amortized Cost, 2017-2019	24,321
Total fixed-maturity securities, Amortized Cost	99,088	$ 60,202
Estimated Fair Value, 2016	74,789
Estimated Fair Value, 2017-2019	24,266
Total fixed-maturity securities, Estimated Fair Value	$ 99,055	$ 60,641