FAIR VALUE MEASUREMENTS - Level 3 fair value inputs (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 947,982	$ 829,156
Net derivative liability	(20,617)	(11,486)
Fixed maturities, available for sale	12,313,200	12,041,799
CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	5,910	6,173
Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	104,521	70,011
Significant unobservable inputs (Level 3)
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	110,431	76,184
Net derivative liability	(5,630)	(9,122)
Fixed maturities, available for sale	42,894	14,909
Significant unobservable inputs (Level 3) | CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	5,910	6,173
Significant unobservable inputs (Level 3) | Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 104,521	$ 70,011
Significant unobservable inputs (Level 3) | Other privately held investments | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity date (years)	3 years
Significant unobservable inputs (Level 3) | Other privately held investments | Minimum
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity date (years)	2 years
Significant unobservable inputs (Level 3) | Other privately held investments | Maximum
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity date (years)	4 years
Significant unobservable inputs (Level 3) | Discount rate
Fair Value Inputs Assets Quantitative Information [Line Items]
Derivative liability, measurement input	0.013
Significant unobservable inputs (Level 3) | Discount rate | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Derivative liability, measurement input	0.013
Significant unobservable inputs (Level 3) | Discount rate | Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.025
Significant unobservable inputs (Level 3) | Discount rate | Other privately held investments | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.025
Significant unobservable inputs (Level 3) | Default rate | Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.005
Significant unobservable inputs (Level 3) | Default rate | Other privately held investments | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.005
Significant unobservable inputs (Level 3) | Loss absorption yield | Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.010
Significant unobservable inputs (Level 3) | Loss absorption yield | Other privately held investments | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.010
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow
Fair Value Inputs Assets Quantitative Information [Line Items]
Net derivative liability	$ (5,630)
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow | CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 5,910
Estimated maturity date (years)	6 years
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow | CLO-Equities | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity date (years)	6 years
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow | Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 20,867
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow | Default rate | CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.045
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow | Default rate | CLO-Equities | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.045
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow | Loss severity rate | CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.500
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow | Loss severity rate | CLO-Equities | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.500
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow | Collateral spread | CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.030
Significant unobservable inputs (Level 3) | Valuation Technique, Discounted Cash Flow | Collateral spread | CLO-Equities | Weighted average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.030
Significant unobservable inputs (Level 3) | Valuation, Market Approach | Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 84,000