FAIR VALUE MEASUREMENTS - Significant Unobservable Inputs (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Fair Value Inputs Assets Quantitative Information [Line Items]
Other investments, at fair value	$ 938,922	$ 930,278
Fixed maturities, available for sale	12,137,475	12,152,753
Significant unobservable inputs (Level 3)
Fair Value Inputs Assets Quantitative Information [Line Items]
Other investments, at fair value	94,347	92,230
Fixed maturities, available for sale	164,965	$ 147,223
Significant unobservable inputs (Level 3) | Valuation, Market Approach
Fair Value Inputs Assets Quantitative Information [Line Items]
Fixed maturities, available for sale	165,000
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow
Fair Value Inputs Assets Quantitative Information [Line Items]
Other investments, at fair value	$ 11,671
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow | Maximum
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity date	4 months 24 days
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity date	4 months 24 days
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow | Discount rate
Fair Value Inputs Assets Quantitative Information [Line Items]
Unobservable input (as a percent)	0.054
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow | Discount rate | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Unobservable input (as a percent)	0.054
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow | Default rate
Fair Value Inputs Assets Quantitative Information [Line Items]
Unobservable input (as a percent)	0.005
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow | Default rate | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Unobservable input (as a percent)	0.005
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow | Loss absorption yield
Fair Value Inputs Assets Quantitative Information [Line Items]
Unobservable input (as a percent)	0.010
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow | Loss absorption yield | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Unobservable input (as a percent)	0.010
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Valuation, Market Approach
Fair Value Inputs Assets Quantitative Information [Line Items]
Other investments, at fair value	$ 83,000