PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Changes in Projected Benefit Obligations of Our Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation beginning of year	$ 5,263	$ 6,795
Service cost	32	37	$ 35
Interest cost	160	236	264
Plan participants’ contributions	0	0
Actuarial (gains) losses	510	(718)
Foreign currency translation	39	(69)
Benefits paid (includes lump sum and annuity transfers)	(1,745)	(1,024)
Plan amendments and other	0	5
Plan transfers	1	1
Projected benefit obligation at end of year	4,260	5,263	6,795
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation beginning of year	166	200
Service cost	0	0	0
Interest cost	6	7	8
Plan participants’ contributions	2	4
Actuarial (gains) losses	(8)	(18)
Foreign currency translation	2	(5)
Benefits paid (includes lump sum and annuity transfers)	(17)	(22)
Plan amendments and other	0	0
Plan transfers	0	0
Projected benefit obligation at end of year	$ 151	$ 166	$ 200