POLICYHOLDER ACCOUNT BALANCES - Aggregate Fair Value of Separate Account Assets (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Policyholder Account Balance [Line Items]
Separate Accounts assets	$ 6,830	$ 5,754
Life Insurance & Employee Benefits Products
Policyholder Account Balance [Line Items]
Separate Accounts assets	2,869	2,642
Individual Variable Annuity Products
Policyholder Account Balance [Line Items]
Separate Accounts assets	3,911	3,100
Employer - Sponsored Products
Policyholder Account Balance [Line Items]
Separate Accounts assets	38
Other
Policyholder Account Balance [Line Items]
Separate Accounts assets	12	12
Mutual Funds
Policyholder Account Balance [Line Items]
Separate Accounts assets	6,830	5,754
Mutual Funds | Life Insurance & Employee Benefits Products
Policyholder Account Balance [Line Items]
Separate Accounts assets	2,869	2,642
Mutual Funds | Individual Variable Annuity Products
Policyholder Account Balance [Line Items]
Separate Accounts assets	3,911	3,100
Mutual Funds | Employer - Sponsored Products
Policyholder Account Balance [Line Items]
Separate Accounts assets	38
Mutual Funds | Other
Policyholder Account Balance [Line Items]
Separate Accounts assets	$ 12	$ 12