Investments - Scheduled Maturities of Company's Fixed Maturity Securities Based on their Fair Values (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Securities with Unrealized Losses, Total	$ 11,499	$ 57,573
Fixed Maturities
Schedule of Available-for-sale Securities [Line Items]
Securities with Unrealized Gains, One year or less	4,759
Securities with Unrealized Gains, After one through five years	35,669
Securities with Unrealized Gains, After five through ten years	56,093
Securities with Unrealized Gains, After ten years	8,937
Securities with Unrealized Gains, No single maturity date	5,899
Securities with Unrealized Gains, Total	111,357
Securities with Unrealized Losses, After one through five years	3,574
Securities with Unrealized Losses, No single maturity date	296
Securities with Unrealized Losses, Total	3,870
All Fixed Maturity Securities, One year or less	4,759
All Fixed Maturity Securities, After one through five years	39,243
All Fixed Maturity Securities, After five through ten years	56,093
All Fixed Maturity Securities, After ten years	8,937
All Fixed Maturity Securities, No single maturity date	6,195
All Fixed Maturity Securities, Total	$ 115,227