RETIREMENT BENEFITS - Contributions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
U.S. | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future cash contributions	$ 0
Cash contributions paid by the Company	50	$ 500
Estimated benefits paid directly by Company	60
Benefits paid directly by the Company	55	56
U.S. | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future cash contributions	0
Cash contributions paid by the Company	140	0
Estimated benefits paid directly by Company	6
Benefits paid directly by the Company	36	6
Non-U.S. | Pension Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future cash contributions	79
Cash contributions paid by the Company	90	82
Estimated benefits paid directly by Company	49
Benefits paid directly by the Company	45	44
Non-U.S. | Postretirement Benefit Plans
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Estimated future cash contributions	4
Cash contributions paid by the Company	4	4
Estimated benefits paid directly by Company	6
Benefits paid directly by the Company	$ 5	$ 5