Scheduled Maturity Dates for Fixed Maturity Securities by Number of Years Until Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value
Due in one year or less	$ 79,279
Due after one year through five years	766,001
Due after five years through ten years	323,003
Due after ten years	421,468
Mortgage-backed and asset-backed securities	824,459
Total	2,414,210	$ 2,365,934
Amortized Cost
Due in one year or less	81,819
Due after one year through five years	767,634
Due after five years through ten years	320,503
Due after ten years	409,648
Mortgage-backed and asset-backed securities	820,641
Total	$ 2,400,245	$ 2,323,959