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, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation beginning of year	$ 6,469	$ 6,211
Service cost	35	48	$ 57
Interest cost	264	277	265
Plan participants’ contributions	0	0
Actuarial (gains) losses	489	120
Foreign currency translation	59	27
Benefits paid (includes lump sum settlements)	(527)	(419)
Plan amendments and other	3	0
Plan transfers	3	1
Plan acquisitions	0	199
Change in control enhanced benefits	0	5
Projected benefit obligation, end of year	6,795	6,469	6,211
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation beginning of year	225	240
Service cost	0	0	0
Interest cost	8	8	9
Plan participants’ contributions	6	7
Actuarial (gains) losses	(18)	(5)
Foreign currency translation	5	3
Benefits paid (includes lump sum settlements)	(26)	(28)
Plan amendments and other	0	0
Plan transfers	0	0
Plan acquisitions	0	0
Change in control enhanced benefits	0	0
Projected benefit obligation, end of year	$ 200	$ 225	$ 240