This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=116868678&loc=d3e1043-128460

Name:	us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

SPECIAL ITEMS SPECIAL ITEMS (Details) - USD ($) $ in Millions	12 Months Ended			49 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Merger-related Costs [Line Items]
Special items - merger-related costs	$ 6	$ 44	$ 87	$ 370
Special items—other	0	0	45
Nondeductible expenses	9	9	9
Virgin America Inc. [Member]
Merger-related Costs [Line Items]
Special items - merger-related costs	6	$ 44	$ 87
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