Fair Value Instruments - Carrying and Estimated Fair Value of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jul. 31, 2020	May 04, 2020	May 01, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Debt and Lease Obligation	$ 10,381				$ 2,678
2.65% Notes due 2020
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	2.65%
2.65% Notes due 2020 | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 0				500
Interest rate stated in the debt agreement (in hundredths)	2.65%
Term Loan Agreement Due 2020 [Member]
Debt Instrument [Line Items]
Secured Debt - Carrying Value	$ 0				$ 134
Interest rate stated in the debt agreement (in hundredths)	5.223%				5.223%
Unsecured Senior Notes Due 2022 - 2.75%
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	2.75%
Unsecured Senior Notes Due 2022 - 2.75% | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 300				$ 300
Interest rate stated in the debt agreement (in hundredths)	2.75%
Total Pass Through Certificates [Member] | Enhanced Equipment Trust Certificate
Debt Instrument [Line Items]
Carrying amount of debt	$ 137				197
Interest rate stated in the debt agreement (in hundredths)	6.24%
Term Loan Agreement Due 2026 - 3.03%
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	1.34%
Term Loan Agreement Due 2026 - 3.03% | Notes Payable to Banks
Debt Instrument [Line Items]
Carrying amount of debt	$ 159				178
Interest rate stated in the debt agreement (in hundredths)	1.34%
Unsecured Senior Notes Due 2026 - 3.00%
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	3.00%
Unsecured Senior Notes Due 2026 - 3.00% | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 300				300
Interest rate stated in the debt agreement (in hundredths)	3.00%
Unsecured Senior Notes Due 2027 - 3.45%
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	3.45%
Unsecured Senior Notes Due 2027 - 3.45% | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	3.45%
7.375% Debentures due 2027
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	7.375%
7.375% Debentures due 2027 | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 119				122
Interest rate stated in the debt agreement (in hundredths)	7.375%
4.750 Unsecured Notes due 2023
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)			4.75%
4.750 Unsecured Notes due 2023 | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 1,250				0
Interest rate stated in the debt agreement (in hundredths)	4.75%
1.250 Convertible Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)				1.25%
1.250 Convertible Senior Notes due 2025 [Member] | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	1.25%
1.250 Convertible Senior Notes due 2025 [Member] | 1.25% convertible notes (a)
Debt Instrument [Line Items]
Carrying amount of debt	$ 1,945				0
Interest rate stated in the debt agreement (in hundredths)				1.25%
5.250 Unsecured Notes due 2025 | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 1,550	$ 300			0
Interest rate stated in the debt agreement (in hundredths)	5.25%
Term Loan Agreement Due 2025 [Member] | Notes Payable to Banks
Debt Instrument [Line Items]
Carrying amount of debt	$ 119				0
Interest rate stated in the debt agreement (in hundredths)	1.65%
3.45 Unsecured Senior Notes due 2027 [Member] | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 300				300
5.125 Notes due 2027 | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 2,000	$ 700			0
Interest rate stated in the debt agreement (in hundredths)	5.125%
1.65 Term Loan Agreement Payable through 2028 [Member] | Notes Payable to Banks
Debt Instrument [Line Items]
Carrying amount of debt	$ 184				0
2.625% Notes due 2030 | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 500				0
Interest rate stated in the debt agreement (in hundredths)	2.625%
1.0 Payroll Support Program Loan due 2030 | Unsecured Debt
Debt Instrument [Line Items]
Carrying amount of debt	$ 976				0
Interest rate stated in the debt agreement (in hundredths)	1.00%
Term Loan Agreement Due 2028 [Member] | Notes Payable to Banks
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (in hundredths)	1.65%
Level 2 | Unsecured Senior Notes Due 2022 - 2.75% | Unsecured Debt
Debt Instrument [Line Items]
Notes Payable, Fair Value	$ 311
Level 2 | Total Pass Through Certificates [Member] | Enhanced Equipment Trust Certificate
Debt Instrument [Line Items]
Notes Payable, Fair Value	140
Level 2 | Unsecured Senior Notes Due 2026 - 3.00% | Unsecured Debt
Debt Instrument [Line Items]
Notes Payable, Fair Value	324
Level 2 | 7.375% Debentures due 2027 | Unsecured Debt
Debt Instrument [Line Items]
Loans Payable, Fair Value	145
Level 2 | 4.750 Unsecured Notes due 2023
Debt Instrument [Line Items]
Notes Payable, Fair Value	1,362
Level 2 | 1.250 Convertible Senior Notes due 2025 [Member] | 1.25% convertible notes (a)
Debt Instrument [Line Items]
Notes Payable, Fair Value	3,359
Level 2 | 5.250 Unsecured Notes due 2025
Debt Instrument [Line Items]
Notes Payable, Fair Value	1,799
Level 2 | 3.45 Unsecured Senior Notes due 2027 [Member] | Unsecured Debt
Debt Instrument [Line Items]
Notes Payable, Fair Value	329
Level 2 | 5.125 Notes due 2027 | Unsecured Debt
Debt Instrument [Line Items]
Notes Payable, Fair Value	2,383
Level 2 | 2.625% Notes due 2030 | Unsecured Debt
Debt Instrument [Line Items]
Notes Payable, Fair Value	515
Level 3 | Term Loan Agreement Due 2026 - 3.03% | Notes Payable to Banks
Debt Instrument [Line Items]
Loans Payable, Fair Value	155
Level 3 | Term Loan Agreement Due 2025 [Member] | Notes Payable to Banks
Debt Instrument [Line Items]
Loans Payable, Fair Value	119
Level 3 | 1.65 Term Loan Agreement Payable through 2028 [Member] | Notes Payable to Banks
Debt Instrument [Line Items]
Loans Payable, Fair Value	183
Level 3 | 1.0 Payroll Support Program Loan due 2030 | Unsecured Debt
Debt Instrument [Line Items]
Loans Payable, Fair Value	953
AirTran Airways | 737 Aircraft Notes payable through 2020
Debt Instrument [Line Items]
Secured Debt - Carrying Value	$ 0				$ 20