LOSS AND LOSS ADJUSTMENT EXPENSE RESERVES - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Liability for Claims and Claims Adjustment Expense
Prior years	$ (943)	$ 10,502
Reinsurance Contract [Axis]: Expected Loss
Liability for Claims and Claims Adjustment Expense
Net loss reserve on prior contracts increase (decrease)		(20,800)
Reinsurance Contract [Axis]: Favorable Loss
Liability for Claims and Claims Adjustment Expense
Net loss reserve on prior contracts increase (decrease)	11,400
Reinsurance Contract [Axis]: Reserve Strengthening
Liability for Claims and Claims Adjustment Expense
Net loss reserve on prior contracts increase (decrease)	(10,500)	31,300
CAT Losses
Liability for Claims and Claims Adjustment Expense
Net loss reserve on prior contracts increase (decrease)	48,900	20,200
Baltimore Bridge Collapse, Hurricane Helene and US Tornados
Liability for Claims and Claims Adjustment Expense
Net loss reserve on prior contracts increase (decrease)	39,900
Turkey Earthquake, New Zealand Cyclone Gabrielle, Severe U.S. Tornados
Liability for Claims and Claims Adjustment Expense
Net loss reserve on prior contracts increase (decrease)		29,500
CAT Development
Liability for Claims and Claims Adjustment Expense
Net loss reserve on prior contracts increase (decrease)	$ (9,000)	$ (9,300)