PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	$ 18	$ 1
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	133	125
Interest cost	218	219
Expected return on plan assets	(406)	(383)
Amortization of prior service credit	(6)	(6)
Amortization of net (gain) loss	171	157
Net periodic benefit cost	110	112
Other Postretirement Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	3	3
Interest cost	11	14
Amortization of net (gain) loss	(6)	(2)
Net periodic benefit cost	$ 8	$ 15