Investments - Fair Value and Gross Unrealized Losses of Fixed Maturity Securities in Continuous Unrealized Loss Position for Greater than 12 Months (Detail) $ in Thousands	Dec. 31, 2016 Security	Dec. 31, 2015 USD ($) Security
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | Security	0	4
Fair Value		$ 7,689
Gross Unrealized Losses		$ (241)
Percentage of amortized cost less than or equal to 10%
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | Security		4
Fair Value		$ 7,689
Gross Unrealized Losses		$ (241)