LEASES (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Operating Lease, Cost	$ 118	$ 120	$ 239	$ 240
Finance Lease, Right-of-Use Asset, Amortization	19	13	34	26
Finance Lease, Interest Expense	6	6	13	12
Finance Lease, Cost	25	19	47	38
Short-term Lease, Cost	71	53	120	107
Variable Lease, Cost	79	48	150	112
Sublease Income	(1)	(1)	(3)	(2)
Lease, Cost	292	$ 239	553	495
Operating Lease, Payments			245	240
Finance Lease, Interest Payment on Liability			13	12
Finance Lease, Principal Payments			29	$ 21
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability			57		$ 185
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability			72		178
Operating lease right-of-use assets	1,745		1,745		1,856
Property	56,564		56,564		56,325
Accumulated depreciation	(36,700)		(36,700)		(36,086)
Total Lease Assets	2,226		2,226		2,305
Operating lease liabilities - current	402		402		416
Finance Lease, Liability, Current	67		67		54
Operating lease liabilities - noncurrent	1,419		1,419		1,521
Finance Lease, Liability, Noncurrent	486		486		464
Total Lease Liabilities	$ 2,374		$ 2,374		$ 2,455
Operating Lease, Weighted Average Remaining Lease Term	7 years 4 months 24 days		7 years 4 months 24 days		7 years 7 months 6 days
Finance Lease, Weighted Average Remaining Lease Term	10 years 7 months 6 days		10 years 7 months 6 days		11 years 7 months 6 days
Operating Lease, Weighted Average Discount Rate, Percent	3.77%		3.77%		3.84%
Finance Lease, Weighted Average Discount Rate, Percent	5.09%		5.09%		5.41%
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 247		$ 247
Finance Lease, Liability, Payments, Remainder of Fiscal Year	47		47
Lessee, Operating Lease, Liability, to be Paid, Year One	408		408
Finance Lease, Liability, to be Paid, Year One	88		88
Lessee, Operating Lease, Liability, Payments, Due Year Two	330		330
Finance Lease, Liability, Payments, Due Year Two	112		112
Lessee, Operating Lease, Liability, Payments, Due Year Three	257		257
Finance Lease, Liability, Payments, Due Year Three	57		57
Lessee, Operating Lease, Liability, Payments, Due Year Four	177		177
Finance Lease, Liability, to be Paid, Year Four	46		46
Lessee, Operating Lease, Liability, Payments, Due Year Five	716		716
Finance Lease, Liability, Payments, Due Year Five	380		380
Lessee, Operating Lease, Liability, Payments, Due	2,135		2,135
Finance Lease, Liability, Payment, Due	730		730
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	314		314
Finance Lease, Liability, Undiscounted Excess Amount	177		177
Operating Lease, Liability	1,821		1,821
Finance lease obligations 2	553		553
Lessee, Additional Leases Not yet Commenced, Assumptions and Judgment, Amount	38		$ 38
Lessee, Additional Leases Not yet Commenced, Term of Contract			10 years
Residual Value Guarantees [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	809		$ 809		$ 818
Guarantor Obligations, Current Carrying Value	19		19		22
Finance Leases [Member]
Property	727		727		665
Accumulated depreciation	$ (246)		$ (246)		$ (216)