Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) Segment	Mar. 31, 2017 USD ($)
Segment Information [Abstract]
Number of reportable segments | Segment	1
Summary of Segment Revenue [Abstract]
Net premiums earned	$ 105,462	$ 73,974
Net investment income	4,636	3,692
Net realized and unrealized gains (losses) on investments	(4,533)	6,294
Commissions and other income	1,814	981
Total revenues	107,379	84,941
Property and Casualty Insurance [Member]
Summary of Segment Revenue [Abstract]
Net premiums earned	105,462	73,974
Net investment income	4,636	3,692
Net realized and unrealized gains (losses) on investments	(4,533)	6,294
Commissions and other income	1,814	981
Total revenues	$ 107,379	$ 84,941