Reinsurance - Reinsurance Programs (Details) - Property and casualty business - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Casualty excess of loss
Reinsurance [Line Items]
Stated Retention	$ 3,000,000	$ 3,000,000	$ 2,500,000
Exhaustion Point	$ 60,000,000	$ 60,000,000	$ 60,000,000
Placement	100.00%	100.00%	100.00%
Placement and Limit	$ 57,000,000	$ 57,000,000	$ 57,500,000
Property excess of loss
Reinsurance [Line Items]
Stated Retention	3,000,000	3,000,000	2,500,000
Exhaustion Point	$ 25,000,000	$ 25,000,000	$ 25,000,000
Placement	100.00%	100.00%	100.00%
Placement and Limit	$ 22,000,000	$ 22,000,000	$ 22,500,000
Surety excess of loss
Reinsurance [Line Items]
Stated Retention	2,000,000	1,500,000	1,500,000
Exhaustion Point	$ 50,000,000	$ 45,000,000	$ 45,000,000
Placement	100.00%	100.00%	100.00%
Placement and Limit	$ 48,000,000	$ 43,500,000	$ 43,500,000
Marine liability quota share
Reinsurance [Line Items]
Exhaustion Point	$ 5,000,000
Placement	70.00%
Placement and Limit	$ 5,000,000
Specialty casualty variable quota share
Reinsurance [Line Items]
Exhaustion Point	$ 5,000,000
Placement	70.00%
Placement and Limit	$ 5,000,000
Property catastrophe, excess
Reinsurance [Line Items]
Stated Retention	20,000,000	15,000,000	20,000,000
Exhaustion Point	$ 110,000,000	$ 180,000,000	$ 250,000,000
Placement	100.00%	100.00%	100.00%
Placement and Limit	$ 107,150,000	$ 165,000,000	$ 230,000,000
Boiler and machinery
Reinsurance [Line Items]
Exhaustion Point	$ 100,000,000	$ 50,000,000	$ 50,000,000
Placement	100.00%	100.00%	100.00%
Placement and Limit	$ 100,000,000	$ 50,000,000	$ 50,000,000
Pillared Occurrence Program
Reinsurance [Line Items]
Stated Retention	6,000,000	5,000,000
Exhaustion Point	$ 16,000,000	$ 15,000,000
Placement	90.00%	100.00%
Placement and Limit	$ 10,000,000	$ 10,000,000
Earthquake Quota Share Program
Reinsurance [Line Items]
Exhaustion Point	$ 170,000,000	$ 180,000,000
Placement	100.00%	100.00%
Placement and Limit	$ 56,525,000	$ 180,000,000