RETIREMENT BENEFITS - Fair Value of Pension and Postretirement Plan Assets by Asset Category (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	$ 2,815	$ 2,807
Level 1
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	91	197
Level 1 | Equity securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	44	101
Level 1 | Equity funds
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 1 | Fixed income funds
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 1 | Corporate debt securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 1 | U.S. Treasury and agency securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 1 | Insurance contracts
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 1 | Cash and cash equivalents
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	47	96
Level 1 | Other
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 2
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	2,216	2,099
Level 2 | Equity securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 2 | Equity funds
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	625	601
Level 2 | Fixed income funds
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	815	783
Level 2 | Corporate debt securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	485	533
Level 2 | U.S. Treasury and agency securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	67	70
Level 2 | Insurance contracts
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 2 | Cash and cash equivalents
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 2 | Other
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	224	112
Level 3
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	172	189
Level 3 | Equity securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 3 | Equity funds
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 3 | Fixed income funds
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 3 | Corporate debt securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 3 | U.S. Treasury and agency securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 3 | Insurance contracts
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	130	149
Level 3 | Cash and cash equivalents
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	0	0
Level 3 | Other
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	42	40
Fair Value, Inputs, Level 1, 2 and 3
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	2,479	2,485
Fair Value, Inputs, Level 1, 2 and 3 | Equity securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	44	101
Fair Value, Inputs, Level 1, 2 and 3 | Equity funds
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	625	601
Fair Value, Inputs, Level 1, 2 and 3 | Fixed income funds
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	815	783
Fair Value, Inputs, Level 1, 2 and 3 | Corporate debt securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	485	533
Fair Value, Inputs, Level 1, 2 and 3 | U.S. Treasury and agency securities
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	67	70
Fair Value, Inputs, Level 1, 2 and 3 | Insurance contracts
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	130	149
Fair Value, Inputs, Level 1, 2 and 3 | Cash and cash equivalents
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	47	96
Fair Value, Inputs, Level 1, 2 and 3 | Other
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	266	152
Fair Value Measured at Net Asset Value Per Share | Plan assets measured at NAV as a practical expedient
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Fair value of pension and postretirement plan asset	$ 336	$ 322