RETIREMENT BENEFITS - Defined Contribution Plans and Postemployment Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Postemployment Retirement Benefits
Service-related expense
Service-related expense	$ 0	$ 0
Interest cost on benefit obligation	0	0
Amortization of unrecognized
Prior service benefit	(8)	(8)
Net actuarial loss	1	1
Total service-related benefit	(7)	(7)
Non-service-related expense (benefit)	6	8
Total net (benefit) expense	(1)	1
U.S. | Postretirement Benefit Plans
Defined Contribution Plans
Company's contributions for defined contribution plans	104	98
Service-related expense
Service-related expense	0	0
Interest cost on benefit obligation	6	6
Amortization of unrecognized
Prior service benefit	0	0
Total net (benefit) expense	3	4
Non-U.S. plans | Postretirement Benefit Plans
Defined Contribution Plans
Company's contributions for defined contribution plans	76	69
Service-related expense
Service-related expense	2	2
Interest cost on benefit obligation	26	24
Amortization of unrecognized
Prior service benefit	(2)	(2)
Total net (benefit) expense	$ 10	$ 11