PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Change in Projected Benefit Obligation, Plan Assets and Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 3,005	$ 3,307
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	3,786	4,150	$ 4,025
Defined Benefit Plan, Service Cost	39	38	39
Defined Benefit Plan, Interest Cost	128	129	131
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	(249)	241
Defined Benefit Plan, Benefit Obligation, Benefits Paid	278	281
Defined Benefit Plan, Other Cost (Credit)	(4)	(2)
Defined Benefit Plan, Plan Assets, Amount	3,005	3,307	$ 3,097
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	(62)	331
Defined Benefit Plan, Plan Assets, Contributions by Employer	42	162
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Assets Transferred to (from) Plan	(4)	(2)
Defined Benefit Plan, Plan Assets, Benefits Paid	278	281
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(781)	(843)
Liability, Defined Benefit Plan, Current	2	2
Liability, Defined Benefit Plan, Noncurrent	779	841
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	(781)	(843)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	(2,019)	(2,083)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax	(11)	(12)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	$ 2,008	$ 2,071
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.32%	3.59%	4.00%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	$ 215	$ 224	$ 264
Defined Benefit Plan, Service Cost	1	1	1
Defined Benefit Plan, Interest Cost	6	8	8
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	(2)	(23)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	14	26
Defined Benefit Plan, Other Cost (Credit)	0	0
Defined Benefit Plan, Plan Assets, Amount	0	0	$ 0
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	0	0
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	0
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Assets Transferred to (from) Plan	0	0
Defined Benefit Plan, Plan Assets, Benefits Paid	0	0
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(215)	(224)
Liability, Defined Benefit Plan, Current	19	15
Liability, Defined Benefit Plan, Noncurrent	196	209
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	(215)	(224)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	79	86
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax	0	0
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	$ (79)	$ (86)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.23%	3.51%