RETIREMENT BENEFITS - Components of Net Periodic Pension Cost (Income) of Pension Plans (Details) - Pension Plan - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost			$ 2	$ 3	$ 4
Interest cost			38	45	65
Expected return on plan assets			(63)	(65)	(70)
Settlement	$ 1	$ 0		1	(13)
Net periodic pension cost (income)			$ (23)	$ (16)	$ (14)