Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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Earliest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Debt - Summary of Debt (Details) - USD ($) $ in Millions	12 Months Ended
Debt - Summary of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total secured and unsecured debt	$ 28,214			$ 9,991
Unamortized (discount)/premium and debt issuance cost, net and other	(240)			115
Total debt	27,974			10,106
Less: current maturities	(1,443)			(2,054)
Total long-term debt	$ 26,531			8,052
Unsecured notes \| Unsecured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2021
Maturity dates range, end	Dec. 31, 2029
Total secured and unsecured debt	$ 5,350			5,550
Unsecured notes \| Unsecured Debt \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	2.90%
Unsecured notes \| Unsecured Debt \| Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	7.38%
Unsecured CARES Act Payroll Support Program Loan \| Unsecured Debt
Debt Instrument [Line Items]
Interest rate per annum (percent)	0.01%
Total secured and unsecured debt	$ 1,648			0
Maturity date	Dec. 31, 2030
SkyMiles Notes \| Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2023
Maturity dates range, end	Dec. 31, 2028
Total secured and unsecured debt	$ 6,000			0
SkyMiles Notes \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	4.50%
SkyMiles Notes \| Secured Debt \| Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	4.75%
SkyMiles Term Loan \| Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2023
Maturity dates range, end	Dec. 31, 2027
Interest rate per annum (percent)	4.75%
Total secured and unsecured debt	$ 3,000			0
2020 Senior Secured Notes \| Secured Debt
Debt Instrument [Line Items]
Interest rate per annum (percent)	7.00%		7.00%
Total secured and unsecured debt	$ 3,500			0
Maturity date	Dec. 31, 2025
2020 Term Loan \| Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2021
Maturity dates range, end	Dec. 31, 2023
Interest rate per annum (percent)	5.75%
Total secured and unsecured debt	$ 1,493			0
2018 Revolving Credit Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2021
Maturity dates range, end	Dec. 31, 2023
Total secured and unsecured debt	$ 0			0
Financings secured by aircraft - Certificates \| Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2021
Maturity dates range, end	Dec. 31, 2028
Total secured and unsecured debt	$ 2,633			1,669
Financings secured by aircraft - Certificates \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	2.00%
Financings secured by aircraft - Certificates \| Secured Debt \| Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	8.02%
Financings secured by aircraft - Notes \| Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2021
Maturity dates range, end	Dec. 31, 2032
Total secured and unsecured debt	$ 1,284			1,193
Financings secured by aircraft - Notes \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	0.81%
Financings secured by aircraft - Notes \| Secured Debt \| Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	5.75%
NYTDC Special Facilities Revenue Bonds, Series 2020 \| Bonds
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2026
Maturity dates range, end	Dec. 31, 2045
Total secured and unsecured debt	$ 1,511	$ 1,500		0
NYTDC Special Facilities Revenue Bonds, Series 2020 \| Bonds \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	4.00%
NYTDC Special Facilities Revenue Bonds, Series 2020 \| Bonds \| Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	5.00%
NYTDC Special Facilities Revenue Bonds, Series 2018 \| Bonds
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2022
Maturity dates range, end	Dec. 31, 2036
Total secured and unsecured debt	$ 1,383			1,383
NYTDC Special Facilities Revenue Bonds, Series 2018 \| Bonds \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	4.00%
NYTDC Special Facilities Revenue Bonds, Series 2018 \| Bonds \| Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	5.00%
Other financings \| Secured and Unsecured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2021
Maturity dates range, end	Dec. 31, 2030
Total secured and unsecured debt	$ 412			196
Other financings \| Secured and Unsecured Debt \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	2.51%
Other financings \| Secured and Unsecured Debt \| Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	8.75%
Other revolving credit facilities \| Revolving Credit Facility
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2021
Maturity dates range, end	Dec. 31, 2022
Total secured and unsecured debt	$ 0			$ 0