Investments - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) Securities	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) Securities	Jun. 30, 2015 USD ($) Securities
Investments Schedule [Abstract]
Individual fixed maturity held in unrealized loss position | Securities	51		51
Individual fixed maturity held in unrealized loss position longer than 12 months | Securities	24		24
Carrying value of investments	$ 10,800,000		$ 10,800,000
Impairment losses recognized			0	$ 2,700,000
Net realized gains (losses) on investments	$ 545,000	$ (2,617,000)	$ 793,000	$ (2,558,000)
Number of fixed maturity securities to be deemed other-than-temporarily impaired | Securities				4
Net realized gain(loss)outside OTTI				$ 100,000