Revenue - Passenger Revenue Breakout (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue
Operating Revenue	$ 22,428	$ 21,965	$ 21,146
Passenger Revenue Non Loyalty
Disaggregation of Revenue
Operating Revenue	17,578	17,506	16,934
Passenger Loyalty Air Transportation
Disaggregation of Revenue
Operating Revenue	2,487	2,307	2,263
Passenger Ancillary Sold Separately
Disaggregation of Revenue
Operating Revenue	711	642	566
Passenger
Disaggregation of Revenue
Operating Revenue	$ 20,776	$ 20,455	$ 19,763

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration