SPECIAL ITEMS SPECIAL ITEMS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Merger-related Costs [Line Items]
Special items - merger-related costs	$ 87	$ 116	$ 117
Special items—other	45	0	0
Nondeductible expenses	9	5	20
Special tax expense (benefit)	0	(237)	17
Virgin America Inc. [Member]
Merger-related Costs [Line Items]
Special items - merger-related costs	87	$ 116	117
Nondeductible expenses			$ 39
Settlement Fee [Member]
Merger-related Costs [Line Items]
Special items—other	20
One-time Bonus Payment [Member]
Merger-related Costs [Line Items]
Special items—other	$ 25