LEASES (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Operating Lease, Expense	$ 120	$ 125
Finance Lease, Right-of-Use Asset, Amortization	13	6
Finance Lease, Interest Expense	6	6
Finance Lease, Cost	19	12
Short-term Lease, Cost	54	50
Variable Lease, Cost	64	44
Sublease Income	(1)	(1)
Lease, Cost	256	230
Operating Lease, Payments	126	133
Finance Lease, Interest Payment on Liability	6	6
Finance Lease, Principal Payments	8	$ 3
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	38		$ 2,476
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	34		89
Operating Lease, Right-of-Use Asset	1,942		2,072
Property, Plant and Equipment, Gross	54,942		54,910
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(34,136)		(33,914)
Total Lease Assets	2,289		2,391
Operating Lease, Liability, Current	384		421
Finance Lease, Liability, Current	49		32
Operating Lease, Liability, Noncurrent	1,622		1,739
Finance Lease, Liability, Noncurrent	369		363
Total Lease Liabilities	$ 2,424		$ 2,555
Operating Lease, Weighted Average Remaining Lease Term	8 years		8 years
Finance Lease, Weighted Average Remaining Lease Term	11 years 6 months		12 years 3 months 18 days
Operating Lease, Weighted Average Discount Rate, Percent	4.10%		4.09%
Finance Lease, Weighted Average Discount Rate, Percent	6.04%		6.28%
Lessee, Operating Lease, Liability, Payments, Due 2020	$ 338
Finance Lease, Liability, Payments, Due 2020	56
Lessee, Operating Lease, Liability, Payments, Due 2021	409
Finance Lease, Liability, Payments, Due 2021	64
Lessee, Operating Lease, Liability, Payments, Due 2022	349
Finance Lease, Liability, Payments, Due 2022	57
Lessee, Operating Lease, Liability, Payments, Due 2023	281
Finance Lease, Liability, Payments, Due 2023	82
Lessee, Operating Lease, Liability, Payments, Due 2024	218
Finance Lease, Liability, Payments, Due 2024	29
Lessee, Operating Lease, Liability, Payments, Due 2025 and thereafter	806
Finance Lease, Liability, Payments, Due 2025 and thereafter	310
Lessee, Operating Lease, Liability, Payments, Due	2,401
Finance Lease, Liability, Payment, Due	598
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	395
Finance Lease, Liability, Undiscounted Excess Amount	180
Operating Lease, Liability	2,006
Finance lease obligations 1	418
Lessor, Operating Lease, Lease Not yet Commenced, Assumption and Judgment, Value of Underlying Asset, Amount	$ 65
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract	20 years
Residual Value Guarantees [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 788		$ 792
Guarantor Obligations, Current Carrying Value	0		0
Finance Leases [Member]
Property, Plant and Equipment, Gross	526		486
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ (179)		(167)
Accounting Standards Update 2016-02 [Member]
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability			$ 2,300