Scheduled Maturity Dates for Fixed Maturity Securities by Number of Years Until Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value
Due in one year or less	$ 64,435
Due after one year through five years	721,735
Due after five years through ten years	350,030
Due after ten years	389,728
Mortgage- and asset-backed securities	788,009
Total	2,313,937	$ 2,365,934
Amortized Cost
Due in one year or less	67,319
Due after one year through five years	713,956
Due after five years through ten years	345,148
Due after ten years	385,292
Mortgage- and asset-backed securities	779,422
Total	$ 2,291,137	$ 2,323,959