Investments - Scheduled Maturities of Company's Fixed Maturity Securities Based on their Fair Values (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Securities with Unrealized Losses, Total	$ 57,573	$ 38,072
Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Securities with Unrealized Gains, One year or less	3,715
Securities with Unrealized Gains, After one through five years	17,383
Securities with Unrealized Gains, After five through ten years	31,952
Securities with Unrealized Gains, After ten years	8,467
Securities with Unrealized Gains, No single maturity date	6,641
Securities with Unrealized Gains, Total	68,158
Securities with Unrealized Losses, One year or less	1,036
Securities with Unrealized Losses, After one through five years	15,650
Securities with Unrealized Losses, After five through ten years	31,854
Securities with Unrealized Losses, No single maturity date	194
Securities with Unrealized Losses, Total	48,734
Securities with No Unrealized Gains or Losses, One year or less	1,550
Securities with No Unrealized Gains or Losses, Total	1,550
All Fixed Maturity Securities, One year or less	6,301
All Fixed Maturity Securities, After one through five years	33,033
All Fixed Maturity Securities, After five through ten years	63,806
All Fixed Maturity Securities, After ten years	8,467
All Fixed Maturity Securities, No single maturity date	6,835
All Fixed Maturity Securities, Total	$ 118,442