Supplemental Financial Information - Accounts and Other Receivables (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Dec. 31, 2020
Accounts and Other Receivables [Abstract]
Trade receivables		$ 59	$ 46
Credit card receivables		92	35
Business partners and other suppliers (a)	[1]	73	274
Taxes receivable (b)	[2]	705	740
Other		8	35
Accounts and other receivables		937	1,130
Cash Tax Refund Expected From CARES Act Loss Carry Back Provision		$ 470	$ 470
CARES Act Loss Carryback Period		5 years
Deferred revenue related to vendor prepayment		$ 323
Amount of Deferred Revenue from Vendor Prepayment that Would Have Been Receivable at Period End		$ 106

[1] In fourth quarter 2020, the Company received a $600 million prepayment from Chase for Rapid Rewards points expected to be purchased during 2021, based on cardholder activity on the Visa credit card associated with its loyalty program. During first quarter 2021, $323 million was reclassified to deferred revenue in Air Traffic liability--loyalty (including $106 million that would have been a receivable from business partners as of March 31, 2021), and the remainder is expected to be reclassified during second quarter 2021.

[2] Both periods include approximately $470 million associated with a significant cash tax refund expected as a result of the CARES Act allowing entities to carry back 2020 losses to prior periods of up to five years, and claim refunds of federal taxes paid. This amount also includes excise taxes remitted to taxing authorities for which the subsequent flights were canceled by Customers, resulting in amounts due back to the Company.