SPECIAL ITEMS SPECIAL ITEMS - MERGER-RELATED COSTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Merger-related Costs [Line Items]
Contracted services	$ 306	$ 314	$ 247
Special items—merger-related costs	87	116	117
Virgin America Inc. [Member]
Merger-related Costs [Line Items]
Contracted services	45	52	32
Severance Costs	13	41	22
Banking Fees and Commissions	0	0	36
Legal Fees	1	3	22
Business Acquisition, Transaction Costs	28	20	5
Special items—merger-related costs	$ 87	$ 116	$ 117