Organization, Description of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Description of Business and Basis of Presentation	Organization, Description of Business and Basis of Presentation United Rentals, Inc. (“Holdings,” “URI” or the “Company”) is principally a holding company and conducts its operations primarily through its wholly owned subsidiary, United Rentals (North America), Inc. (“URNA”), and subsidiaries of URNA. Holdings’ primary asset is its sole ownership of all issued and outstanding shares of common stock of URNA. URNA’s various credit agreements and debt instruments place restrictions on its ability to transfer funds to its shareholder. We rent equipment to a diverse customer base that includes construction and industrial companies, manufacturers, utilities, municipalities, homeowners and government entities. We primarily operate in the United States and Canada, and have a limited presence in Europe, Australia and New Zealand. In July 2018, we completed the acquisition of BakerCorp International Holdings, Inc. (“BakerCorp”), which allowed for our entry into select European markets. As discussed in note 3 to the condensed consolidated financial statements, in May 2021, we completed the acquisition of General Finance Corporation (“General Finance”), which allowed for our entry into select markets in Australia and New Zealand. In addition to renting equipment, we sell new and used rental equipment, as well as related contractor supplies, parts and service. We have prepared the accompanying unaudited condensed consolidated financial statements in accordance with the accounting policies described in our annual report on Form 10-K for the year ended December 31, 2020 (the “2020 Form 10-K”) and the interim reporting requirements of Form 10-Q. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) have been condensed or omitted. These unaudited condensed consolidated financial statements should be read in conjunction with the 2020 Form 10-K. In our opinion, all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair presentation of financial condition, operating results and cash flows for the interim periods presented have been made. Interim results of operations are not necessarily indicative of the results of the full year. COVID-19 The novel coronavirus (“COVID-19”) was first identified in people in late 2019. COVID-19 spread rapidly throughout the world and, in March 2020, the World Health Organization characterized COVID-19 as a pandemic. COVID-19 is a pandemic of respiratory disease spreading from person-to-person that poses a serious public health risk. It has significantly disrupted supply chains and businesses around the world. The extent and duration of the COVID-19 impact, on the operations and financial position of United Rentals, and on the global economy, is uncertain. Uncertainty remains regarding emerging variant strains of COVID-19, and regarding the length of time it will take for the COVID-19 pandemic to subside, including the time it will take for vaccines to be broadly distributed and accepted in the United States and the rest of the world, and the effectiveness of such vaccines in slowing or stopping the spread of COVID-19 and mitigating the economic effects of the pandemic. The health and safety of our employees and customers remains our top priority, and we have also engaged in extensive contingency planning to manage the business impact of the pandemic. Prior to mid-March 2020, our results were largely in line with expectations. We began to experience a decline in revenues in March 2020, when rental volume declined in response to shelter-in-place orders and other market restrictions. The volume declines were more pronounced in 2020 than 2021, and we have seen recent evidence of recovery across our construction and industrial markets, as well as encouraging gains in end-market indicators. COVID-19 is discussed in more detail throughout “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” New Accounting Pronouncements Guidance Adopted in 2021 Simplifying the Accounting for Income Taxes. In December 2019, the FASB issued guidance intended to simplify the accounting for income taxes. The guidance removes the following exceptions: 1) exception to the incremental approach for intraperiod tax allocation when there is a loss from continuing operations and income or a gain from other items, 2) exception to the requirement to recognize a deferred tax liability for equity method investments when a foreign subsidiary becomes an equity method investment, 3) exception to the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary and 4) exception to the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. Additionally, the guidance simplifies the accounting for income taxes by: 1) requiring that an entity recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax, 2) requiring that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction, 3) specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements (although the entity may elect to do so (on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority), 4) requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date and 5) making minor improvements for income tax accounting related to employee stock ownership plans and investments in qualified affordable housing projects accounted for using the equity method. Different components of the guidance required retrospective, modified retrospective or prospective adoption. We adopted this guidance when it became effective, in the first quarter of 2021, and the impact on our financial statements was not material.