SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment, net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Less: accumulated depreciation and amortization	$ (20,370)	$ (18,671)
Total property and equipment, net	33,109	28,749
Flight equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 38,091	33,368
Flight equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	25 years
Flight equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	34 years
Ground property and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 8,996	7,758
Ground property and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Ground property and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years
Information technology-related assets
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3,375	3,389
Information technology-related assets | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Information technology-related assets | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Flight and ground equipment under finance leases
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,950	2,052
Less: accumulated depreciation and amortization	(463)	(456)
Advance payments for equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,067	$ 853