FAIR VALUE MEASUREMENTS - Level 3 fair value inputs (Details) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 829,156	$ 770,923
Net derivative liability	(11,486)	(13,637)
Fixed maturities	12,041,799	12,468,205
CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	6,173	14,328
Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	70,011	36,934
Significant unobservable inputs (Level 3)
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	76,184	51,262
Net derivative liability	(9,122)	(9,672)
Fixed maturities	14,909	8,021
Significant unobservable inputs (Level 3) \| Valuation Technique, Discounted Cash Flow
Fair Value Inputs Assets Quantitative Information [Line Items]
Net derivative liability	(9,122)
Significant unobservable inputs (Level 3) \| Valuation, Market Approach
Fair Value Inputs Assets Quantitative Information [Line Items]
Fixed maturities	15,000
Significant unobservable inputs (Level 3) \| CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	6,173	14,328
Significant unobservable inputs (Level 3) \| Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 70,011	$ 36,934
Estimated maturity dates (years)	5 years
Significant unobservable inputs (Level 3) \| Other privately held investments \| Valuation Technique, Discounted Cash Flow
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 21,643
Significant unobservable inputs (Level 3) \| Other privately held investments \| Valuation, Market Approach
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 48,000
Significant unobservable inputs (Level 3) \| Other privately held investments \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity dates (years)	5 years
Significant unobservable inputs (Level 3) \| CLO-Equities \| CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity dates (years)	5 years
Significant unobservable inputs (Level 3) \| CLO-Equities \| CLO-Equities \| Valuation Technique, Discounted Cash Flow
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value	$ 6,173
Significant unobservable inputs (Level 3) \| CLO-Equities \| CLO-Equities \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Estimated maturity dates (years)	5 years
Default rates \| Significant unobservable inputs (Level 3) \| Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.005
Default rates \| Significant unobservable inputs (Level 3) \| Other privately held investments \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.005
Default rates \| Significant unobservable inputs (Level 3) \| CLO-Equities \| CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.045
Default rates \| Significant unobservable inputs (Level 3) \| CLO-Equities \| CLO-Equities \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.045
Loss severity rate \| Significant unobservable inputs (Level 3) \| CLO-Equities \| CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.500
Loss severity rate \| Significant unobservable inputs (Level 3) \| CLO-Equities \| CLO-Equities \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.500
Collateral spreads \| Significant unobservable inputs (Level 3) \| CLO-Equities \| CLO-Equities
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.030
Collateral spreads \| Significant unobservable inputs (Level 3) \| CLO-Equities \| CLO-Equities \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.030
Loss absorption yield \| Significant unobservable inputs (Level 3) \| Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.010
Loss absorption yield \| Significant unobservable inputs (Level 3) \| Other privately held investments \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.010
Discount rate \| Significant unobservable inputs (Level 3)
Fair Value Inputs Assets Quantitative Information [Line Items]
Derivative liability, measurement input	0.004
Discount rate \| Significant unobservable inputs (Level 3) \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Derivative liability, measurement input	0.004
Discount rate \| Significant unobservable inputs (Level 3) \| Other privately held investments
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.013
Discount rate \| Significant unobservable inputs (Level 3) \| Other privately held investments \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Discounted cash flow	0.013

The estimated remaining time to maturity of the CLO structure (expressed as a number of years).

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- Definition

Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

+ References

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- Definition

Value of input used to measure alternative investment.

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Value of input used to measure derivative liability.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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