Amount, after accumulated amortization, of debt discount.

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Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Debt - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Unamortized debt discount	$ 479
Revolving Credit Facility \| United Airlines, Inc. \| Secured Debt
Debt Instrument [Line Items]
Available under revolving credit facility		$ 1,750