RETIREMENT BENEFITS - Sensitivities of Certain Key Assumptions (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
U.S. | Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Effect of one-percentage-point increase in discount rates	$ 8
Effect of one-percentage-point decrease in discount rates	(12)
U.S. | Postretirement Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Effect of one-percentage-point increase in discount rates	0
Effect of one-percentage-point decrease in discount rates	(1)
Non-U.S. plans | Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Effect of one-percentage-point increase in discount rates	(3)
Effect of one-percentage-point decrease in discount rates	6
Non-U.S. plans | Postretirement Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Effect of one-percentage-point increase in discount rates	(2)
Effect of one-percentage-point decrease in discount rates	$ 3