Investments - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017 USD ($) Security	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Investments Schedule [Abstract]
Individual fixed maturity held in unrealized loss position | Security	201
Individual fixed maturity held in unrealized loss position longer than 12 months | Security	16
Carrying value of investments	$ 8,956,000		$ 13,330,000
Impairment losses recognized	0	$ 0
Net realized gains (losses) on investments	$ (181,000)	$ 248,000