Special Items (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Property, Plant and Equipment [Line Items]
Special Items - CARES Act Payroll Support	$ (332)	$ 0	$ (636)	$ 0
Special Items - Fleet Impairment	56	0	258	0
Special Items - Severance and Benefit Costs	58	0	58	0
Special Items - Severance and Benefit Costs	39
Sale and Leaseback Transaction, Gain (Loss), Net	106	0	106	0
Special Items - E190 Fleet Transition	0	(3)	0	6
Special Items - Union Contract Costs	0	3	0	8
Special Items	$ (112)	$ 0	$ (214)	$ 14

Amount of gain (loss) on sale and leaseback transaction from transfer of asset accounted for as sale.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 40
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121606570&loc=SL77919786-209982

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

Name:	us-gaap_SaleAndLeasebackTransactionGainLossNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration