Investments - Schedule of Selected Information about Sales of Fixed Maturities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales	$ 14,331	[1]	$ 11,444
Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales	14,331		11,444
Gross realized gains	495		84
Gross realized losses	$ (214)		$ 0

[1] Due to the adoption of ASU 2016-09, the excess tax benefits from stock option exercises of $2 million for the quarter ended March 31, 2016 were presented as a component of operating activities in the same manner as other cash flows related to income taxes. See further discussion at Note 2—New Accounting Standards.