Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Results of Operations (Unaudited) [Abstract]
Net premiums earned	$ 120,273	$ 117,853	$ 97,730	$ 109,659	$ 111,357	$ 110,288	$ 115,631	$ 110,012	$ 445,515	$ 447,288	$ 432,880
Net investment income	6,321	5,486	6,379	7,236	6,815	6,703	6,500	6,231	25,422	26,249	22,048
Net realized and unrealized gains (losses) on investments	7,761	144	10,615	(27,756)	3,848	125	2,889	6,027	(9,236)	12,889	(25,691)
Losses and loss expenses incurred	84,246	84,673	68,208	81,831	86,132	84,781	90,433	87,122	318,958	348,468	345,864
Net income (loss)	$ 11,971	$ 3,281	$ 11,367	$ (22,156)	$ 3,771	$ (707)	$ 1,535	$ 2,748	$ 4,463	$ 7,347	$ (34,075)
Net income (loss) per diluted share (in dollars per share)	$ 0.84	$ 0.23	$ 0.80	$ (1.56)	$ 0.26	$ (0.05)	$ 0.11	$ 0.18	$ 0.31	$ 0.50	$ (2.28)