Worldwide Pandemic (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended				60 Months Ended
	Dec. 31, 2020 USD ($) aircraft employees shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2015	Apr. 19, 2030	Jan. 15, 2021 USD ($) shares	Dec. 27, 2020 USD ($)	Jun. 30, 2020 USD ($)	Apr. 09, 2020 $ / shares	Mar. 30, 2020 USD ($)
Proceeds from term loan credit facility	$ 3,683	$ 0	$ 0
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	27.80%	22.20%		35.00%
Proceeds from Payroll Support Program Grant	$ 3,400
Cash Raised, Net of Fees	$ 18,900
Class of Warrant or Right, Outstanding | shares	2,700
Proceeds from Payroll Support Program Grant Received in June 2020								$ 652
Voluntary Separation Program 2020 Participants | employees	4,200
Voluntary Separation Program 2020 and Extended Emergency Time Off Total Accrued	$ 914
Extended Emergency Time Off Accrual for Employees who Accepted through 2020	$ 620
Number of Aircraft Grounded Under Emergency Order on March 13, 2019 | aircraft	34
Number of Aircraft in Long-Term Storage | aircraft	92
Proceeds from Payroll Support Program Grant Allocated to Fund Salaries, Wages, and Benefits	$ 2,300
Costs Incurred for Voluntary Separation Program 2020 and Extended ETO	1,400
Goodwill	970	$ 970
Proceeds from Payroll Support Program Extension Grant of Consolidated Appropriations Act that will be Used to Offset Salaries, Wages, and Benefits Expenses in 1Q21	1,700
Unsecured Term Loan to be Issued Through Payroll Support Program Extension of Consolidated Appropriations Act	259
Total Proceeds to be Provided to U.S. Airlines from Payroll Support Program Extension Grant of Consolidated Appropriations Act							$ 15,000
Voluntary Separation Program 2020 and Extended Emergency Time Off Relieved from Accrual for Employees Who Accepted Through December 31, 2020	$ 454
Total Employees who participated in Extended Emergency Time Off During 2020 | employees	11,000
Total Employees who Participated in Extended Emergency Time Off During 2020, Who Were Still on Emergency Time Off at December 31, 2020 | employees	10,421
Impairment of indefinite-lived Intangibles, excluding goodwill	$ 0
Goodwill impairment	0
Loss on asset impairment	(32)	0	$ 0
Goodwill	$ 970	970
B-737-700
Total aircraft retired in 4Q20 | aircraft	20
Option to Convert to Voluntary Separation Program 2020 [Member]
Extended Emergency Time Off Period	12 months
Subsequent Event
Proceeds from Payroll Support Program Extension Grant Received in January 2021						$ 864
Minimum
Extended Emergency Time Off Period	6 months
Maximum
Extended Emergency Time Off Period	18 months
Customer Support and Service [Member]
Voluntary Separation Program 2020 Participants | employees	390
Ground Operations and Provisioning [Member]
Voluntary Separation Program 2020 Participants | employees	1,060
Flight Attendants [Member]
Voluntary Separation Program 2020 Participants | employees	725
Pilots [Member]
Voluntary Separation Program 2020 Participants | employees	630
Pilots [Member] | Maximum
Extended Emergency Time Off Period	5 years
Contract groups [Member]
Voluntary Separation Program 2020 Participants | employees	90
Managerial and Administrative [Member]
Voluntary Separation Program 2020 Participants | employees	1,140
Maintenance [Member]
Voluntary Separation Program 2020 Participants | employees	185
LUV Common Stock Warrants
Class of Warrant or Right, Outstanding | shares	2,700
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares									$ 36.47
Warrants and Rights Outstanding	$ 40
Class of Warrant or Right, Unissued | shares	560
LUV Common Stock Warrants | Subsequent Event
Class of Warrant or Right, Outstanding | shares						495
Common Stock | Subsequent Event
Warrants and Rights Outstanding						$ 9
Use Rights [Member]
Gross carrying amount of indefinite-lived intangible assets	$ 295
CARES Act Unsecured Loan | Unsecured Debt
Interest rate stated in the debt agreement (in hundredths)	1.00%
Unsecured Debt | Forecast | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Spread on variable rate					2.00%
1.0 Payroll Support Program Loan due 2030 | Unsecured Debt
Interest rate stated in the debt agreement (in hundredths)	1.00%
Carrying amount of debt	$ 976	$ 0
1.0 Payroll Support Program Loan due 2031 [Member] | Subsequent Event
Carrying amount of debt						$ 229
Accordian Feature to Amended 364-Day Term Loan Credit Facility [Member] | Amended 364-Day Term Loan Credit Facility
Accordian Feature on Short-term Debt										$ 417