Consolidated Balance Sheets - FY (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investments:
Fixed maturity securities available-for-sale, amortized cost	$ 422,255	$ 413,526
Equity securities available-for-sale, cost	$ 45,916	$ 14,350
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	21,036,087	20,968,707
Common stock, shares outstanding (in shares)	21,036,087	20,968,707