Investments - Fair Value and Gross Unrealized Losses of Fixed Maturity Securities in Continuous Unrealized Loss Position for Greater than 12 Months (Detail) $ in Thousands	Sep. 30, 2015 USD ($) Security	Dec. 31, 2014 USD ($) Security
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | Security	4	9
Fair Value	$ 7,796	$ 20,567
Gross Unrealized Losses	$ (165)	$ (592)
Percentage of amortized cost less than or equal to 10%
Schedule of Available-for-sale Securities [Line Items]
Number of Securities | Security	4	9
Fair Value	$ 7,796	$ 20,567
Gross Unrealized Losses	$ (165)	$ (592)