Investment Securities - Schedule of Amortized Cost and Estimated Fair Value of Fixed-Maturity Securities by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Maturity in:
Amortized Cost, 2014	$ 63,371
Amortized Cost, 2015-2019	73,083
Total fixed-maturity securities, Amortized Cost	136,454	217,587
Estimated Fair Value, 2014	63,368
Estimated Fair Value, 2015-2019	73,648
Total fixed-maturity securities, Estimated Fair Value	$ 137,016	$ 218,801