Schedule of Long-term Debt (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Finance leases	$ 627	$ 845
Total	2,678	3,396
Less current maturities	819	606
Less debt discount and issuance costs	13	19
Long-term debt less current maturities	1,846	2,771
Finance lease, current maturities of long-term debt	85
Finance lease, long-term debt less current maturities	542
2.75% Unsecured Senior Notes Due November 2019
Debt Instrument [Line Items]
Unsecured Debt	$ 0	300
Interest rate stated in the debt agreement (in hundredths)	2.75%
Debt Instrument, Maturity Date Range, Start	Nov. 06, 2014
Debt Instrument, Maturity Date Range, End	Nov. 06, 2019
Term Loan Agreement payable through May 2019 - 6.315%
Debt Instrument [Line Items]
Secured Debt	$ 0	23
Interest rate stated in the debt agreement (in hundredths)	6.315%
Debt Instrument, Maturity Date Range, Start	Apr. 29, 2009
Debt Instrument, Maturity Date Range, End	May 06, 2019
Term Loan Agreement payable through July 2019 - 4.84%
Debt Instrument [Line Items]
Secured Debt	$ 0	10
Interest rate stated in the debt agreement (in hundredths)	4.84%
Debt Instrument, Maturity Date Range, Start	Jul. 01, 2009
Debt Instrument, Maturity Date Range, End	Jul. 01, 2019
2.65% Notes due 2020
Debt Instrument [Line Items]
Unsecured Debt	$ 500	492
Interest rate stated in the debt agreement (in hundredths)	2.65%
Debt Instrument, Maturity Date Range, Start	Nov. 05, 2015
Debt Instrument, Maturity Date Range, End	Nov. 05, 2020
2.65% Notes due 2020 \| Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	2.65%
Term Loan Agreement payable through 2020 - 5.223%
Debt Instrument [Line Items]
Secured Debt	$ 134	187
Interest rate stated in the debt agreement (in hundredths)	5.223%
Debt Instrument, Maturity Date Range, Start	May 09, 2008
Debt Instrument, Maturity Date Range, End	May 09, 2020
Term Loan Agreement payable through 2020 - 5.223% \| Notes Payable to Banks
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	5.223%
737 Aircraft Notes payable through 2020 \| AirTran Airways
Debt Instrument [Line Items]
Secured Debt	$ 20	67
Debt Instrument, Maturity Date Range, Start	May 08, 2006
Debt Instrument, Maturity Date Range, End	Apr. 03, 2020
Unsecured Senior Notes Due 2022 - 2.75%
Debt Instrument [Line Items]
Unsecured Debt	$ 300	300
Interest rate stated in the debt agreement (in hundredths)	2.75%
Debt Instrument, Maturity Date Range, Start	Nov. 16, 2017
Debt Instrument, Maturity Date Range, End	Nov. 16, 2022
Pass Through Certificates due 2022 - 6.24% \| Enhanced Equipment Trust Certificate
Debt Instrument [Line Items]
Secured Debt	$ 197	250
Interest rate stated in the debt agreement (in hundredths)	6.24%
Debt Instrument, Maturity Date Range, Start	Oct. 03, 2017
Debt Instrument, Maturity Date Range, End	Aug. 01, 2022
Term Loan Agreement Due 2026 - 3.03%
Debt Instrument [Line Items]
Secured Debt	$ 178	197
Interest rate stated in the debt agreement (in hundredths)	3.03%
Debt Instrument, Maturity Date Range, Start	Oct. 31, 2016
Debt Instrument, Maturity Date Range, End	Oct. 31, 2026
Unsecured Senior Notes Due 2026 - 3.00%
Debt Instrument [Line Items]
Unsecured Debt	$ 300	300
Interest rate stated in the debt agreement (in hundredths)	3.00%
Debt Instrument, Maturity Date Range, Start	Nov. 04, 2016
Debt Instrument, Maturity Date Range, End	Nov. 15, 2026
Unsecured Senior Notes Due 2027 - 3.45%
Debt Instrument [Line Items]
Unsecured Debt	$ 300	300
Interest rate stated in the debt agreement (in hundredths)	3.45%
Debt Instrument, Maturity Date Range, Start	Nov. 16, 2017
Debt Instrument, Maturity Date Range, End	Nov. 16, 2027
7.375% Debentures due 2027
Debt Instrument [Line Items]
Unsecured Debt	$ 122	$ 125
Interest rate stated in the debt agreement (in hundredths)	7.375%
Debt Instrument, Maturity Date Range, Start	Feb. 28, 1997
Debt Instrument, Maturity Date Range, End	Mar. 01, 2027

Amount of short-term and long-term debt and lease obligation.

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