Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Available-for-sale securities, amortized cost	$ 1,633,875	$ 1,659,760
Available-for-sale securities, allowance for credit losses	59	0
Trading securities, amortized cost	10,502	11,941
Equity securities, cost	66,992	67,529
Allowance for doubtful accounts	1,170	1,239
Property and equipment accumulated depreciation	51,122	50,183
Reinsurance receivables and recoverables, allowance for credit losses	$ 46	$ 0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	75,000,000	75,000,000
Common stock, shares issued (in shares)	25,016,093	25,015,963
Common stock, shares outstanding (in shares)	25,016,093	25,015,963