Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Segment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 Segment
Segment Information [Abstract]
Number of reportable segments | Segment			1		2
Summary of Segment Revenue [Abstract]
Net premiums earned	$ 89,100	$ 71,235	$ 231,070	$ 206,870
Net investment income	4,027	3,513	12,434	10,501
Net realized gains on investments	5,944	7,732	15,534	17,024
Commissions and other income	1,407	1,207	3,789	4,035
Total revenues	100,478	83,687	262,827	238,430
Property and Casualty Insurance [Member]
Summary of Segment Revenue [Abstract]
Net premiums earned	89,100	71,235	231,070	206,870
Net investment income	4,027	3,513	12,434	10,501
Net realized gains on investments	5,944	7,732	15,534	17,024
Commissions and other income	1,407	1,207	3,789	4,035
Total revenues	$ 100,478	$ 83,687	$ 262,827	$ 238,430