FAIR VALUE MEASUREMENTS - Significant Unobservable Inputs (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Fair Value Inputs Assets Quantitative Information [Line Items]
Other investments, at fair value	$ 938,562	$ 930,278
Fixed maturities, available for sale	11,865,480	12,152,753
Significant unobservable inputs (Level 3)
Fair Value Inputs Assets Quantitative Information [Line Items]
Other investments, at fair value	97,020	92,230
Fixed maturities, available for sale	166,885	$ 147,223
Significant unobservable inputs (Level 3) | Valuation, Market Approach
Fair Value Inputs Assets Quantitative Information [Line Items]
Fixed maturities, available for sale	167,000
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	$ 15,376
Significant unobservable inputs (Level 3) | Other investments - Other privately held investments | Discounted cash flow | Minimum
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity date	0 years
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	1 year
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	1 year
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)	0.057
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)	0.057
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	$ 82,000