Reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Premiums Written [Abstract]
Direct									$ 574,181	$ 581,070	$ 504,033
Ceded on direct									(122,676)	(138,102)	(151,348)
Net direct									451,505	442,968	352,685
Assumed									737	1,430	704
Ceded on assumed									0	0	0
Net assumed									737	1,430	704
Net									452,242	444,398	353,389
Premiums Earned [Abstract]
Direct									570,959	562,364	470,158
Ceded on direct									(124,446)	(131,080)	(145,201)
Net direct									446,513	431,284	324,957
Assumed									775	1,596	3,188
Ceded on assumed									0	0	0
Net assumed									775	1,596	3,188
Net	$ 111,357	$ 110,288	$ 115,631	$ 110,012	$ 118,671	$ 96,807	$ 111,940	$ 105,462	447,288	432,880	328,145
Net losses and loss expenses incurred reduced by ceded reinsurance recoveries									121,927	148,173	128,086
Net losses and loss (benefit) expense incurred from reinsurance assumed from non-affiliates									193	1,300	$ 5,223
Components of reinsurance recoverable [Abstract]
Case unpaid losses, net of valuation allowance	166,675				163,011				166,675	163,011
Incurred but not reported unpaid losses and loss expenses	230,459				211,805				230,459	211,805
Paid losses and loss expenses	20,334				1,250				20,334	1,250
Unearned premiums	14,599				16,370				14,599	16,370
Reinsurance recoverable	$ 432,067				$ 392,436				$ 432,067	$ 392,436