Investment Securities - Schedule of Amortized Cost and Estimated Fair Value of Fixed-Maturity Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Investments Debt And Equity Securities [Abstract]
Amortized Cost, 2016	$ 74,792
Amortized Cost, 2017-2019	23,236
Total fixed-maturity securities, Amortized Cost	98,028	$ 99,088
Estimated Fair Value, 2016	74,820
Estimated Fair Value, 2017-2019	23,306
Total fixed-maturity securities, Estimated Fair Value	$ 98,126	$ 99,055