RETIREMENT BENEFITS PLANS - Fair Value of Other Postretirement Benefits Plan Assets (Details) - Other postretirement benefits plans - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Fair Value of Other Postretirement Benefits Plan Assets [Line Items]
Cash equivalents	$ 3	$ 3
Common Collective Trusts, Fixed Income	16	17
Total other postretirement benefits plan assets	19	20
Quoted prices in active markets for identical assets (Level 1)
Fair Value of Other Postretirement Benefits Plan Assets [Line Items]
Cash equivalents	3	3
Total other postretirement benefits plan assets	3	3
Other observable inputs (Level 2)
Fair Value of Other Postretirement Benefits Plan Assets [Line Items]
Cash equivalents	0	0
Total other postretirement benefits plan assets	0	0
Unobservable inputs (Level 3)
Fair Value of Other Postretirement Benefits Plan Assets [Line Items]
Cash equivalents	0	0
Total other postretirement benefits plan assets	$ 0	$ 0