Overview	12 Months Ended
Dec. 31, 2020
Unusual or Infrequent Items, or Both [Abstract]
Overview	Overview United Airlines Holdings, Inc. (together with its consolidated subsidiaries, "UAL" or the "Company") is a holding company and its principal, wholly-owned subsidiary is United Airlines, Inc. (together with its consolidated subsidiaries, "United"). As UAL consolidates United for financial statement purposes, disclosures that relate to activities of United also apply to UAL, unless otherwise noted. United's operating revenues and operating expenses comprise nearly 100% of UAL's revenues and operating expenses. In addition, United comprises approximately the entire balance of UAL's assets, liabilities and operating cash flows. When appropriate, UAL and United are named specifically for their individual contractual obligations and related disclosures and any significant differences between the operations and results of UAL and United are separately disclosed and explained. We sometimes use the words "we," "our," "us," and the "Company" in this report for disclosures that relate to all of UAL and United. Recent Developments The novel coronavirus (COVID-19) pandemic, together with the measures implemented or recommended by governmental authorities and private organizations in response to the pandemic, has had an adverse impact that has been material to the Company's business, operating results, financial condition and liquidity. The Company began experiencing a significant decline in international and domestic demand related to COVID-19 during the first quarter of 2020. The decline in demand caused a material deterioration in our revenues in 2020, resulting in a net loss of $7.1 billion. The full extent of the ongoing impact of COVID-19 on the Company's longer-term operational and financial performance will depend on future developments, including those outside our control related to the efficacy and speed of vaccination programs in curbing the spread of the virus, the introduction and spread of new variants of the virus which may be resistant to currently approved vaccines, passenger testing requirements, mask mandates or other restrictions on travel, all of which are highly uncertain and cannot be predicted with certainty In response to decreased demand, the Company cut, relative to 2019 capacity, approximately 57% of its scheduled capacity for 2020. In the first quarter of 2021, the Company expects scheduled capacity to be down at least 51% versus the first quarter of 2019. The Company plans to continue to proactively evaluate and cancel flights on a rolling 60-day basis until it sees signs of a recovery in demand and expects demand to remain suppressed, relative to 2019 levels, until vaccines for COVID-19 are widely distributed and are effective in curbing the spread of the virus. In addition, the Company does not currently expect the recovery from COVID-19 to follow a linear path. As such, the Company's actual flown capacity may differ materially from its currently scheduled capacity. The Company has taken a number of actions in response to the decreased demand for air travel. In addition to the schedule reductions discussed above, the Company has: •reduced its planned capital expenditures and reduced operating expenditures in 2020 (including by postponing projects deemed non-critical to the Company's operations); •terminated its share repurchase program; •issued or entered into approximately $13.4 billion in new secured notes, secured term loan facilities and new aircraft financings in 2020, including short term borrowings that were paid in 2020; •borrowed $1.0 billion under the $2.0 billion revolving credit facility established under the Amended and Restated Credit and Guaranty Agreement (the "Credit Agreement"); •availed itself of financial assistance and/or financing made available by the U.S. Treasury Department ("Treasury"), as further described below; •raised approximately $2.1 billion in cash proceeds from the issuance and sale of UAL common stock in 2020; •entered into agreements to finance certain aircraft currently subject to purchase agreements through sale and leaseback transactions; •elected to defer the payment of $199 million in payroll taxes incurred through December 31, 2020, as provided by the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act"), until December 2021, at which time 50% is due, with the remaining amount due December 2022; and •taken a number of actions to reduce employee-related costs, including, among other items, the Company's Chief Executive Officer and President waived 100% of their respective base salaries through the end of 2020, other officers temporarily waived a portion of their base salaries, the Company's non-employee directors waived 100% of their cash compensation for the second and third quarters of 2020, the Company suspended merit salary increases for 2020 and implemented a temporary four-day work week for management and administrative employees and the Company offered voluntary unpaid leaves of absence. The Company also entered into an agreement with its pilots to distribute fewer flight hours to a larger number of pilots, while also reaching agreements to provide a path to early retirement and reduce expense through voluntary leave of absence programs. In addition, and as announced in July 2020, the Company started the involuntary furlough process by issuing Worker Adjustment and Retraining Notification ("WARN") Act notices to 36,000 of its employees. Since then, the Company worked to reduce the total number of furloughs to approximately 13,000 employees by working closely with its union partners, introducing new voluntary options selected by approximately 9,000 employees and proposing creative solutions that would save jobs. As a result of the Company's entry into the PSP2 Agreement, as described below, the Company issued recall notices to these furloughed employees and others impacted by furlough mitigation programs. See the discussion below for more detail about the PSP2 Agreement and the recall process. The Company continues to focus on reducing expenses and managing its liquidity. We expect to continue to modify our cost management structure and capacity as the timing of demand recovery becomes more certain. On March 27, 2020, the President of the United States signed the CARES Act into law. The CARES Act is intended to respond to the COVID-19 pandemic and its impact on the economy, public health, state and local governments, individuals, and businesses. The CARES Act also provides supplemental appropriations for federal agencies to respond to the COVID-19 pandemic. On April 20, 2020, United entered into a Payroll Support Program Agreement (the "PSP Agreement") with Treasury providing the Company with total funding of approximately $5.1 billion pursuant to the Payroll Support Program established under the CARES Act. These funds were used to pay for the wages, salaries and benefits of United employees. Approximately $3.6 billion of the $5.1 billion was provided as a direct grant, and approximately $1.5 billion consists of indebtedness evidenced by a 10-year senior unsecured promissory note (the "PSP Note"). See Note 2 of this report for additional information related to warrants issued in connection with the PSP Note and Note 10 of this report for a discussion of the PSP Note. During 2020, UAL and United entered into a loan and guarantee agreement with Treasury. The agreement provides for a term loan facility of up to approximately $7.5 billion (the "CARES Act Term Loan Facility") pursuant to the loan program established under Section 4003(b)(1) of the CARES Act (the "Loan Program"). The loans (the "CARES Act Term Loans") may be disbursed in up to three disbursements on or before May 28, 2021. On September 28, 2020, United borrowed, and recorded as Long-term debt on the Company's consolidated balance sheet, $520 million under the CARES Act Term Loan Facility, the proceeds of which were used to pay certain transaction fees and expenses and for working capital and other general corporate purposes of the Company. See Note 2 of this report for additional information related to warrants issued in connection with the CARES Act Term Loans and Note 10 of this report for a discussion of the CARES Act Term Loans. Under the PSP Agreement and the Loan Program, the Company and its business are subject to certain restrictions, including, but not limited to, restrictions on the payment of dividends and the ability to repurchase UAL's equity securities, requirements to maintain certain levels of scheduled service and certain limitations on executive compensation. On January 15, 2021, United entered into a Payroll Support Agreement (the "PSP2 Agreement") with Treasury providing the Company with total funding of approximately $2.6 billion, pursuant to the Payroll Support Program established under Subtitle A of Title IV of Division N of the Consolidated Appropriations Act, 2021 (the "PSP Extension Law"). These funds were used to pay for the wages, salaries and benefits of United employees, including the payment of lost wages, salaries and benefits to returning employees. Approximately $1.9 billion was provided as a direct grant and approximately $753 million consists of indebtedness evidenced by a 10-year senior unsecured promissory note (the "PSP2 Note"). As of February 25, 2021, we have received a total of $1.3 billion. See Note 2 of this report for additional information on warrants issued in connection with the PSP2 Note and Note 10 of this report for a discussion of the PSP2 Note. Pursuant to the PSP2 Agreement, the Company is required to comply with certain provisions of the PSP Extension Law, including, among others, the requirement that all funds provided under the Payroll Support Program will be used by United exclusively for the continuation of payment of its U.S. employee wages, salaries and benefits, including the payment of lost wages, salaries and benefits to returning U.S. employees; requirements to maintain U.S. employment levels from the date of the PSP2 Agreement through March 31, 2021; requirements to recall (as such term is defined in the PSP2 Agreement), any U.S. employees subject to involuntary termination or furlough between October 1, 2020 and the date of the PSP2 Agreement, compensate such returning employees for certain lost salary, wages and benefits between December 1, 2020 and the date of the PSP2 Agreement and restore certain rights and protections for such returning employees; provisions prohibiting certain reductions in U.S. employee wages, salaries and benefits; provisions prohibiting the payment of dividends and the repurchase of certain equity until March 31, 2022; and provisions restricting the payment of certain executive compensation until October 1, 2022. As a result of the PSP2 Agreement, the Company offered employment, through March 2021, to employees who were impacted by involuntary furloughs. Because the Company cannot predict with certainty whether it will receive further payroll support from the federal government or when demand for air travel will increase in the short term, the Company is preparing for the possibility that these recalled employees might again be furloughed as soon as the end of the first quarter of 2021. The Company may record additional costs associated with these actions in the first quarter of 2021. Also, in order to reduce the number of such furloughs, during the first quarter of 2021, the Company offered voluntary leave and other programs to certain of its frontline employees, the cost of which cannot be estimated at this time.

United Airlines Holdings, Inc. (together with its consolidated subsidiaries, "UAL" or the "Company") is a holding company and its principal, wholly-owned subsidiary is United Airlines, Inc. (together with its consolidated subsidiaries, "United"). As UAL consolidates United for financial statement purposes, disclosures that relate to activities of United also apply to UAL, unless otherwise noted. United's operating revenues and operating expenses comprise nearly 100% of UAL's revenues and operating expenses. In addition, United comprises approximately the entire balance of UAL's assets, liabilities and operating cash flows. When appropriate, UAL and United are named specifically for their individual contractual obligations and related disclosures and any significant differences between the operations and results of UAL and United are separately disclosed and explained. We sometimes use the words "we," "our," "us," and the "Company" in this report for disclosures that relate to all of UAL and United.

The novel coronavirus (COVID-19) pandemic, together with the measures implemented or recommended by governmental authorities and private organizations in response to the pandemic, has had an adverse impact that has been material to the Company's business, operating results, financial condition and liquidity.

The Company began experiencing a significant decline in international and domestic demand related to COVID-19 during the first quarter of 2020. The decline in demand caused a material deterioration in our revenues in 2020, resulting in a net loss of $7.1 billion. The full extent of the ongoing impact of COVID-19 on the Company's longer-term operational and financial performance will depend on future developments, including those outside our control related to the efficacy and speed of vaccination programs in curbing the spread of the virus, the introduction and spread of new variants of the virus which may be resistant to currently approved vaccines, passenger testing requirements, mask mandates or other restrictions on travel, all of which are highly uncertain and cannot be predicted with certainty

In response to decreased demand, the Company cut, relative to 2019 capacity, approximately 57% of its scheduled capacity for 2020. In the first quarter of 2021, the Company expects scheduled capacity to be down at least 51% versus the first quarter of 2019. The Company plans to continue to proactively evaluate and cancel flights on a rolling 60-day basis until it sees signs of a recovery in demand and expects demand to remain suppressed, relative to 2019 levels, until vaccines for COVID-19 are widely distributed and are effective in curbing the spread of the virus. In addition, the Company does not currently expect the recovery from COVID-19 to follow a linear path. As such, the Company's actual flown capacity may differ materially from its currently scheduled capacity.

•elected to defer the payment of $199 million in payroll taxes incurred through December 31, 2020, as provided by the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act"), until December 2021, at which time 50% is due, with the remaining amount due December 2022; and

•taken a number of actions to reduce employee-related costs, including, among other items, the Company's Chief Executive Officer and President waived 100% of their respective base salaries through the end of 2020, other officers temporarily waived a portion of their base salaries, the Company's non-employee directors waived 100% of their cash compensation for the second and third quarters of 2020, the Company suspended merit salary increases for 2020 and implemented a temporary four-day work week for management and administrative employees and the Company offered voluntary unpaid leaves of absence. The Company also entered into an agreement with its pilots to distribute fewer flight hours to a larger number of pilots, while also reaching agreements to provide a path to early retirement and reduce expense through voluntary leave of absence programs.

In addition, and as announced in July 2020, the Company started the involuntary furlough process by issuing Worker Adjustment and Retraining Notification ("WARN") Act notices to 36,000 of its employees. Since then, the Company worked to reduce the total number of furloughs to approximately 13,000 employees by working closely with its union partners, introducing new voluntary options selected by approximately 9,000 employees and proposing creative solutions that would save jobs. As a result of the Company's entry into the PSP2 Agreement, as described below, the Company issued recall notices to these furloughed employees and others impacted by furlough mitigation programs. See the discussion below for more detail about the PSP2 Agreement and the recall process.

The Company continues to focus on reducing expenses and managing its liquidity. We expect to continue to modify our cost management structure and capacity as the timing of demand recovery becomes more certain.

On March 27, 2020, the President of the United States signed the CARES Act into law. The CARES Act is intended to respond to the COVID-19 pandemic and its impact on the economy, public health, state and local governments, individuals, and businesses. The CARES Act also provides supplemental appropriations for federal agencies to respond to the COVID-19 pandemic.

On April 20, 2020, United entered into a Payroll Support Program Agreement (the "PSP Agreement") with Treasury providing the Company with total funding of approximately $5.1 billion pursuant to the Payroll Support Program established under the CARES Act. These funds were used to pay for the wages, salaries and benefits of United employees. Approximately $3.6 billion of the $5.1 billion was provided as a direct grant, and approximately $1.5 billion consists of indebtedness evidenced by a 10-year senior unsecured promissory note (the "PSP Note"). See Note 2 of this report for additional information related to warrants issued in connection with the PSP Note and Note 10 of this report for a discussion of the PSP Note.

During 2020, UAL and United entered into a loan and guarantee agreement with Treasury. The agreement provides for a term loan facility of up to approximately $7.5 billion (the "CARES Act Term Loan Facility") pursuant to the loan program established under Section 4003(b)(1) of the CARES Act (the "Loan Program"). The loans (the "CARES Act Term Loans") may be disbursed in up to three disbursements on or before May 28, 2021. On September 28, 2020, United borrowed, and recorded as Long-term debt on the Company's consolidated balance sheet, $520 million under the CARES Act Term Loan Facility, the proceeds of which were used to pay certain transaction fees and expenses and for working capital and other general corporate purposes of the Company. See Note 2 of this report for additional information related to warrants issued in connection with the CARES Act Term Loans and Note 10 of this report for a discussion of the CARES Act Term Loans.

Under the PSP Agreement and the Loan Program, the Company and its business are subject to certain restrictions, including, but not limited to, restrictions on the payment of dividends and the ability to repurchase UAL's equity securities, requirements to maintain certain levels of scheduled service and certain limitations on executive compensation.

On January 15, 2021, United entered into a Payroll Support Agreement (the "PSP2 Agreement") with Treasury providing the Company with total funding of approximately $2.6 billion, pursuant to the Payroll Support Program established under Subtitle A of Title IV of Division N of the Consolidated Appropriations Act, 2021 (the "PSP Extension Law"). These funds were used to pay for the wages, salaries and benefits of United employees, including the payment of lost wages, salaries and benefits to returning employees. Approximately $1.9 billion was provided as a direct grant and approximately $753 million consists of indebtedness evidenced by a 10-year senior unsecured promissory note (the "PSP2 Note"). As of February 25, 2021, we have received a total of $1.3 billion. See Note 2 of this report for additional information on warrants issued in connection with the PSP2 Note and Note 10 of this report for a discussion of the PSP2 Note.

Pursuant to the PSP2 Agreement, the Company is required to comply with certain provisions of the PSP Extension Law, including, among others, the requirement that all funds provided under the Payroll Support Program will be used by United exclusively for the continuation of payment of its U.S. employee wages, salaries and benefits, including the payment of lost wages, salaries and benefits to returning U.S. employees; requirements to maintain U.S. employment levels from the date of the PSP2 Agreement through March 31, 2021; requirements to recall (as such term is defined in the PSP2 Agreement), any U.S. employees subject to involuntary termination or furlough between October 1, 2020 and the date of the PSP2 Agreement, compensate such returning employees for certain lost salary, wages and benefits between December 1, 2020 and the date of the

PSP2 Agreement and restore certain rights and protections for such returning employees; provisions prohibiting certain reductions in U.S. employee wages, salaries and benefits; provisions prohibiting the payment of dividends and the repurchase of certain equity until March 31, 2022; and provisions restricting the payment of certain executive compensation until October 1, 2022.

As a result of the PSP2 Agreement, the Company offered employment, through March 2021, to employees who were impacted by involuntary furloughs. Because the Company cannot predict with certainty whether it will receive further payroll support from the federal government or when demand for air travel will increase in the short term, the Company is preparing for the possibility that these recalled employees might again be furloughed as soon as the end of the first quarter of 2021. The Company may record additional costs associated with these actions in the first quarter of 2021. Also, in order to reduce the number of such furloughs, during the first quarter of 2021, the Company offered voluntary leave and other programs to certain of its frontline employees, the cost of which cannot be estimated at this time.