Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Fixed maturities available for sale, at amortized cost	$ 576,911	$ 370,967
Equity securities, cost	$ 34,190	$ 32,439
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	29,740,441	30,441,410
Common stock, shares outstanding	28,840,443	30,441,410
Treasury stock, shares	1,759,330