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, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 3,148	$ 3,005
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	4,097	3,786	$ 4,150
Defined Benefit Plan, Service Cost	34	39	38
Defined Benefit Plan, Interest Cost	145	128	129
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	453	(249)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	280	278
Defined Benefit Plan, Other Cost (Credit)	(41)	(4)
Defined Benefit Plan, Plan Assets, Amount	3,148	3,005	$ 3,307
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)	464	(62)
Defined Benefit Plan, Plan Assets, Contributions by Employer	2	42
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Assets Transferred to (from) Plan	(43)	(4)
Defined Benefit Plan, Plan Assets, Benefits Paid	280	278
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(949)	(781)
Liability, Defined Benefit Plan, Current	2	2
Liability, Defined Benefit Plan, Noncurrent	947	779
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	(949)	(781)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	(2,137)	(2,019)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax	(10)	(11)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	$ 2,127	$ 2,008
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.29%	4.32%	3.59%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	$ 220	$ 215	$ 224
Defined Benefit Plan, Service Cost	1	1	1
Defined Benefit Plan, Interest Cost	7	6	8
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	12	(2)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	15	14
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	(220)	(215)
Liability, Defined Benefit Plan, Current	17	19
Liability, Defined Benefit Plan, Noncurrent	203	196
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position	(220)	(215)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax	60	79
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	$ (60)	$ (79)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.17%	4.23%