PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 132	$ 126	$ 265	$ 251
Interest cost	217	220	435	439
Expected return on plan assets	(404)	(385)	(810)	(768)
Amortization of prior service credit	(6)	(6)	(12)	(12)
Amortization of net (gain) loss	170	158	341	315
Curtailment/settlement 1	0	(6)	0	(6)
Net periodic benefit cost	109	107	219	219
Other Postretirement Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	3	3	6	6
Interest cost	11	13	22	27
Amortization of net (gain) loss	(6)	(1)	(12)	(3)
Net periodic benefit cost	$ 8	$ 15	$ 16	$ 30