RETIREMENT BENEFITS PLANS - Change in Plan Level 3 Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Balance at January 1	$ 5,600
Balance at December 31	5,919	$ 5,600
Unobservable inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Balance at January 1	358
Balance at December 31	535	358
Unobservable inputs (Level 3) | Real estate
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Balance at January 1	184
Balance at December 31	216	184
Unobservable inputs (Level 3) | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Balance at January 1	174
Balance at December 31	319	174
Pension plans | Unobservable inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Balance at January 1	358	190
Gains (losses) relating to assets still held at year-end	89	14
Purchases, sales, settlements - net	83	154
Transfers into or out of Level 3	5	0
Balance at December 31	535	358
Pension plans | Unobservable inputs (Level 3) | Real estate
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Balance at January 1	184	61
Gains (losses) relating to assets still held at year-end	28	2
Purchases, sales, settlements - net	4	121
Transfers into or out of Level 3	0	0
Balance at December 31	216	184
Pension plans | Unobservable inputs (Level 3) | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Balance at January 1	174	129
Gains (losses) relating to assets still held at year-end	61	12
Purchases, sales, settlements - net	79	33
Transfers into or out of Level 3	5	0
Balance at December 31	$ 319	$ 174