Investments, Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest [Abstract]
Taxable bonds	$ 14,853	$ 9,474	$ 6,233
Municipal bonds (tax exempt)	3,692	4,298	3,619
Cash equivalents and short-term investments	842	1,017	678
Dividends on equity securities	2,136	2,014	1,041
Gross investment income	21,523	16,803	11,571
Investment expenses	(1,390)	(1,115)	(1,002)
Net investment income	$ 20,133	$ 15,688	$ 10,569