Statutory Net Income and Surplus (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Statutory Net Income and Surplus
Statutory net income	$ 66,197
Statutory capital and surplus	$ 782,200
Period of statutory measurement of income and dividends	12 months
Maximum available for dividends without approval	$ 78,220
Company's insurance company subsidiaries
Statutory Net Income and Surplus
Statutory net income	66,197	$ 97,169	$ 121,446
Statutory capital and surplus	$ 782,200	$ 826,979
Dividend limitation without prior permission, percentage of preceding surplus	10.00%
Period allowed for Commissioner to object to notice of an extraordinary dividend	30 days
Restricted net assets amount	$ 703,980
Number of levels of regulatory action, risk-based capital law | item	4
Minimum statutory capital and surplus or company action level risk-based capital	$ 200,806
Safety Insurance Company
Statutory Net Income and Surplus
Statutory capital and surplus	782,200
Recorded dividends	$ 94,260