PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Net Periodic Benefit Cost and Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income for All Significant Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets for Plan Benefits, Defined Benefit Plan	$ 4,100	$ 4,000
Service cost	38	39	$ 44
Interest cost	129	131	164
Expected return on plan assets	(221)	(217)	(226)
Amortization of prior service credit	(1)	(1)	(1)
Amortization of net (gain) loss	83	75	87
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	28	27	68
Net (gain) loss	131	208	34
Prior service cost (credit) arising during period	0	0	4
Amortization of prior service (cost) credit	1	1	1
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	(83)	(75)	(87)
Total recognized in other comprehensive (income) loss	49	134	(48)
Total recognized in net periodic benefit cost and other comprehensive loss	77	161	20
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1
Interest cost	8	8	10
Expected return on plan assets	0	0	0
Amortization of prior service credit	0	0	(1)
Amortization of net (gain) loss	(6)	(7)	(10)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	3	2	0
Net (gain) loss	(23)	4	19
Prior service cost (credit) arising during period	0	0	0
Amortization of prior service (cost) credit	0	0	1
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	6	7	10
Total recognized in other comprehensive (income) loss	(17)	11	30
Total recognized in net periodic benefit cost and other comprehensive loss	$ (14)	$ 13	$ 30