Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) Segment	Jun. 30, 2018 USD ($)
Segment Information [Abstract]
Number of reportable segments | Segment			1
Summary of Segment Revenue [Abstract]
Net premiums earned	$ 115,631	$ 111,940	$ 225,644	$ 217,402
Net investment income	6,500	5,796	12,732	10,432
Net realized and unrealized gains (losses) on investments	2,889	(3,435)	8,916	(7,968)
Commissions and other income	1,978	2,263	4,043	4,076
Total revenues	126,998	116,564	251,335	223,942
Property and Casualty Insurance [Member]
Summary of Segment Revenue [Abstract]
Net premiums earned	115,631	111,940	225,644	217,402
Net investment income	6,500	5,796	12,732	10,432
Net realized and unrealized gains (losses) on investments	2,889	(3,435)	8,916	(7,968)
Commissions and other income	1,978	2,263	4,043	4,076
Total revenues	$ 126,998	$ 116,564	$ 251,335	$ 223,942