Scheduled Maturity Dates for Fixed Maturity Securities by Number of Years Until Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value
Due in one year or less	$ 98,463
Due after one year through five years	842,667
Due after five years through ten years	289,220
Due after ten years	433,492
Mortgage-backed and asset-backed securities	968,471
Total	2,632,313	$ 2,414,210
Amortized Cost
Due in one year or less	100,526
Due after one year through five years	827,241
Due after five years through ten years	273,903
Due after ten years	405,896
Mortgage-backed and asset-backed securities	951,055
Total	$ 2,558,621	$ 2,400,245