Investments - Contractual Maturites of Fixed Maturity Investments Classified as Held-to-Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Amortized Cost
One year or less	$ 17,293
More than one year through two years	23,600
More than two years through five years	66,940
More than five years through ten years	107,660
More than ten years	555,162
Amortized Cost	770,655	$ 790,866
Fair Value
One year or less	17,318
More than one year through two years	23,784
More than two years through five years	68,813
More than five years through ten years	110,845
More than ten years	587,419
Fair Value	$ 808,179	$ 769,071
% of Total Fair Value
One year or less	2.10%
More than one year through two years	3.00%
More than two years through five years	8.50%
More than two years through five years	13.70%
More than ten years	72.70%
Percentage of Total Fair Value	100.00%