FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets by Pricing Source, Securities Carried at Amortized Cost (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	$ 18,245	$ 19,657
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	17,319	18,662
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	926	995
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Government and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	17,474	18,829
Government and agencies | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	17,319	18,662
Government and agencies | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	155	167
Government and agencies | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Government and agencies | Third party pricing vendor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	17,474	18,829
Government and agencies | Third party pricing vendor | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	17,319	18,662
Government and agencies | Third party pricing vendor | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	155	167
Government and agencies | Third party pricing vendor | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Municipalities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	285	307
Municipalities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Municipalities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	285	307
Municipalities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Municipalities | Third party pricing vendor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	285	307
Municipalities | Third party pricing vendor | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Municipalities | Third party pricing vendor | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	285	307
Municipalities | Third party pricing vendor | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Public utilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	36	38
Public utilities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Public utilities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	36	38
Public utilities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Public utilities | Third party pricing vendor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	36	38
Public utilities | Third party pricing vendor | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Public utilities | Third party pricing vendor | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	36	38
Public utilities | Third party pricing vendor | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Sovereign and supranational
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	431	462
Sovereign and supranational | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Sovereign and supranational | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	431	462
Sovereign and supranational | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Sovereign and supranational | Third party pricing vendor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	213	226
Sovereign and supranational | Third party pricing vendor | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Sovereign and supranational | Third party pricing vendor | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	213	226
Sovereign and supranational | Third party pricing vendor | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Sovereign and supranational | Internal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	218	236
Sovereign and supranational | Internal | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Sovereign and supranational | Internal | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	218	236
Sovereign and supranational | Internal | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Other corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	19	21
Other corporate | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Other corporate | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	19	21
Other corporate | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Other corporate | Third party pricing vendor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	19	21
Other corporate | Third party pricing vendor | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	0	0
Other corporate | Third party pricing vendor | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	19	21
Other corporate | Third party pricing vendor | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity securities, held-to-maturity, fair value	$ 0	$ 0