Variable Interest Entities ("VIE")	12 Months Ended
Variable Interest Entities ("VIE")	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities (VIE)	VARIABLE INTEREST ENTITIES ("VIE") Variable interests are contractual, ownership or other monetary interests in an entity that change with fluctuations in the fair value of the entity's net assets exclusive of variable interests. A VIE can arise from items such as lease agreements, loan arrangements, guarantees or service contracts. An entity is a VIE if (a) the entity lacks sufficient equity or (b) the entity's equity holders lack power or the obligation and right as equity holders to absorb the entity's expected losses or to receive its expected residual returns. If an entity is determined to be a VIE, the entity must be consolidated by the primary beneficiary. The primary beneficiary is the holder of the variable interests that has the power to direct the activities of a VIE that (i) most significantly impact the VIE's economic performance and (ii) has the obligation to absorb losses of or the right to receive benefits from the VIE that could potentially be significant to the VIE. Therefore, the Company must identify which activities most significantly impact the VIE's economic performance and determine whether it, or another party, has the power to direct those activities. Airport Leases. United is the lessee of real property under long-term operating leases at a number of airports where we are also the guarantor of approximately $1.9 billion of tax-exempt special facilities revenue bonds and interest thereon as of December 31, 2020. These leases are typically with municipalities or other governmental entities, which are excluded from the consolidation requirements concerning a VIE. To the extent United's leases and related guarantees are with a separate legal entity other than a governmental entity, United is not the primary beneficiary because the lease terms are consistent with market terms at the inception of the lease and the lease does not include a residual value guarantee, fixed-price purchase option, or similar feature. See Note 13 of this report for more information regarding United's guarantee of the tax-exempt special facilities revenue bonds. EETCs. United evaluated whether the pass-through trusts formed for its EETC financings, treated as either debt or aircraft operating leases, are VIEs required to be consolidated by United under applicable accounting guidance, and determined that the pass-through trusts are VIEs. Based on United's analysis as described below, United determined that it does not have a variable interest in the pass-through trusts. The primary risk of the pass-through trusts is credit risk (i.e. the risk that United, the issuer of the equipment notes, may be unable to make its principal and interest payments). The primary purpose of the pass-through trust structure is to enhance the credit worthiness of United's debt obligation through certain bankruptcy protection provisions, a liquidity facility (in certain of the EETC structures) and improved loan-to-value ratios for more senior debt classes. These credit enhancements lower United's total borrowing cost. Pass-through trusts are established to receive principal and interest payments on the equipment notes purchased by the pass-through trusts from United and remit these proceeds to the pass-through trusts' certificate holders. United does not invest in or obtain a financial interest in the pass-through trusts. Rather, United has an obligation to make interest and principal payments on its equipment notes held by the pass-through trusts. United does not intend to have any voting or non-voting equity interest in the pass-through trusts or to absorb variability from the pass-through trusts. Based on this analysis, the Company determined that it is not required to consolidate the pass-through trusts. BRW. Synergy's wholly-owned affiliate, BRW, is a special purpose entity created to be the borrower of the BRW Term Loan. BRW is also the owner of the collateral that secures the BRW Term Loan. BRW is a VIE and United holds variable interests in BRW including the BRW Term Loan. However, United is not the primary beneficiary of BRW because it does not hold BRW equity and does not have management rights at BRW and therefore does not have the power to direct the activities that most significantly impact BRW's economic performance. In connection with the delivery by United of a notice of default to BRW, Kingsland was granted, in accordance with the agreements related to the BRW Term Loan Agreement, authority to manage BRW. AVH. United concluded that AVH is a VIE and that United holds a variable interest through the AVH DIP Loan and a call option on BRW's AVH shares. However, United is not the primary beneficiary because it does not hold a material number of shares of AVH and does not have the power through the AVH DIP Loan Agreement or any other agreement to direct the activities that most significantly impact AVH's economic performance. Further, AVH is currently in Chapter 11 bankruptcy and as such the bankruptcy court is viewed as having power to direct the activities that most significantly impact AVH's economic performance. See Note 9 of this report for more information about the AVH call options. ManaAir. United concluded that ManaAir is a VIE as of December 31, 2020. United holds a variable interest in ManaAir in the form of equity interest, but United is not the primary beneficiary because it does not have power to direct the activities that most significantly impact ManaAir's economic performance. Champlain. United concluded that Champlain is a VIE as of December 31, 2020. United holds variable interests in Champlain in the form of equity interest and a loan to Champlain, but United is not the primary beneficiary because it does not have power to direct the activities that most significantly impact Champlain's economic performance.