FAIR VALUE MEASUREMENTS - Fair Value Measurement Inputs and Valuation Techniques (Details) $ in Millions		Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		$ 70,130	$ 73,290
Equity securities		762	1,088
Total assets		79,652	80,325
Level 3
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		1,918	1,781
Equity securities		159	248
Total assets		2,077	2,029
Adjusted cost valuation technique | Level 3 | Private Financials
Fair Value Measurement Inputs and Valuation Techniques
Equity securities		159	248
Municipalities
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		2,210	2,298
Municipalities | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		0	0
Mortgage- and asset-backed securities
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		3,385	3,086
Mortgage- and asset-backed securities | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		859	772
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3 | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		$ 859	$ 772
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3 | Lower Limit | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[1]	85.28	84.81
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3 | Upper Limit | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[1]	105.35	105.89
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3 | Weighted Average | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[1]	99.24	99.39
Public utilities
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		$ 7,313	$ 7,592
Public utilities | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		507	253
Public utilities | Consensus pricing valuation technique | Level 3 | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale			$ 253
Public utilities | Consensus pricing valuation technique | Level 3 | Lower Limit | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[1]		94.34
Public utilities | Consensus pricing valuation technique | Level 3 | Upper Limit | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[1]		102.99
Public utilities | Consensus pricing valuation technique | Level 3 | Weighted Average | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[1]		96.46
Public utilities | Discounted cash flow technique | Level 3 | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		$ 507
Public utilities | Discounted cash flow technique | Level 3 | Lower Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[2]	0.0175
Public utilities | Discounted cash flow technique | Level 3 | Upper Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[2]	0.0225
Public utilities | Discounted cash flow technique | Level 3 | Weighted Average | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[2]	0.0208
Sovereign and supranational
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		$ 490	$ 537
Sovereign and supranational | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		28	30
Sovereign and supranational | Consensus pricing valuation technique | Level 3 | Offered Quotes
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		28	30
Banks/financial institutions
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		8,899	8,835
Banks/financial institutions | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		74	78
Banks/financial institutions | Discounted cash flow technique | Level 3 | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		74	78
Other corporate
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		27,019	28,342
Other corporate | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		450	648
Other corporate | Discounted cash flow technique | Level 3 | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale		$ 450	$ 648
Other corporate | Discounted cash flow technique | Level 3 | Lower Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[2]	0.0069	0.0069
Other corporate | Discounted cash flow technique | Level 3 | Upper Limit | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[2]	0.0388	0.0423
Other corporate | Discounted cash flow technique | Level 3 | Weighted Average | Credit Spreads
Fair Value Measurement Inputs and Valuation Techniques
Fixed maturity securities, available-for-sale, measurement input	[2]	0.0183	0.0206

[1] Represents prices for securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques.

[2] Actual or equivalent credit spreads in basis points.