Debt - Summary of Debt (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt, gross	$ 9,991	$ 9,308
Unamortized premium and debt issuance cost, net and other	115	60
Total debt	10,106	9,368
Less: current maturities	(2,054)	(1,409)
Total long-term debt	$ 8,052	7,959
Unsecured notes \| Unsecured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2020
Maturity dates range, end	Dec. 31, 2029
Debt, gross	$ 5,550	4,050
Unsecured notes \| Unsecured Debt \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	2.60%
Unsecured notes \| Unsecured Debt \| Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	4.38%
Financings secured by aircraft - Certificates \| Secured Debt
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2020
Maturity dates range, end	Dec. 31, 2027
Debt, gross	$ 1,669	1,837
Financings secured by aircraft - Certificates \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	3.20%
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, 2020
Maturity dates range, end	Dec. 31, 2025
Debt, gross	$ 1,193	1,787
Financings secured by aircraft - Notes \| Secured Debt \| Minimum
Debt Instrument [Line Items]
Interest rate per annum (percent)	1.99%
Financings secured by aircraft - Notes \| Secured Debt \| Maximum
Debt Instrument [Line Items]
Interest rate per annum (percent)	6.08%
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
Debt, gross	$ 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
Debt, gross	$ 196	251
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%
2018 Unsecured Revolving Credit Facility \| Revolving Credit Facility
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2021
Maturity dates range, end	Dec. 31, 2023
Debt, gross	$ 0	0
Other revolving credit facilities \| Revolving Credit Facility
Debt Instrument [Line Items]
Maturity dates range, start	Jan. 01, 2020
Maturity dates range, end	Dec. 31, 2021
Debt, gross	$ 0	$ 0

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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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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