Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Segment	Sep. 30, 2017 USD ($)
Segment Information [Abstract]
Number of reportable segments | Segment			1
Summary of Segment Revenue [Abstract]
Net premiums earned	$ 96,807	$ 89,100	$ 314,209	$ 231,070
Net investment income	5,578	4,027	16,010	12,434
Net realized and unrealized gains (losses) on investments	2,373	5,944	(5,595)	15,534
Commissions and other income	3,413	1,407	7,488	3,789
Total revenues	108,171	100,478	332,112	262,827
Property and Casualty Insurance [Member]
Summary of Segment Revenue [Abstract]
Net premiums earned	96,807	89,100	314,209	231,070
Net investment income	5,578	4,027	16,010	12,434
Net realized and unrealized gains (losses) on investments	2,373	5,944	(5,595)	15,534
Commissions and other income	3,413	1,407	7,488	3,789
Total revenues	$ 108,171	$ 100,478	$ 332,112	$ 262,827