Organization, Description of Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2019
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 in the United States, Canada and Europe. 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, 2018 (the “2018 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 2018 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. New Accounting Pronouncements Measurement of Credit Losses on Financial Instruments. In June 2016, the Financial Accounting Standards Board ("FASB") issued guidance that will require companies to present assets held at amortized cost and available for sale debt securities net of the amount expected to be collected. The guidance requires the measurement of expected credit losses to be based on relevant information from past events, including historical experiences, current conditions and reasonable and supportable forecasts that affect collectibility. The guidance will be effective for fiscal years and interim periods beginning after December 15, 2019 and early adoption is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Different components of the guidance require modified retrospective or prospective adoption. This guidance does not apply to receivables arising from operating leases. As discussed in note 2 to the condensed consolidated financial statements, most of our equipment rental revenue is accounted for as lease revenue (such revenue represented 78 percent of our total revenues for the three months ended March 31, 2019). We are currently assessing whether we will early adopt this guidance, and the impact on our financial statements, while limited to our non-operating lease receivables, is not currently estimable, as it will depend on market conditions and our forecast expectations upon, and following, adoption. Simplifying the Test for Goodwill Impairment. In January 2017, the FASB issued guidance intended to simplify the subsequent accounting for goodwill acquired in a business combination. Prior guidance required utilizing a two-step process to review goodwill for impairment. A second step was required if there was an indication that an impairment may exist, and the second step required calculating the potential impairment by comparing the implied fair value of the reporting unit's goodwill (as if purchase accounting were performed on the testing date) with the carrying amount of the goodwill. The new guidance eliminates the second step from the goodwill impairment test. Under the new guidance, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and then recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value (although the loss should not exceed the total amount of goodwill allocated to the reporting unit). The guidance requires prospective adoption and will be effective for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption of this guidance is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We are currently assessing whether we will early adopt. The guidance is not expected to have a significant impact on our financial statements. Guidance Adopted in 2019 Leases. See note 8 to our condensed consolidated financial statements for a discussion of our lease accounting following our adoption of an updated FASB lease accounting standard in the first quarter of 2019. Derivatives and Hedging. In 2019, we prospectively adopted guidance intended to improve the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements. The guidance is additionally intended to simplify hedge accounting, and no longer requires separate measurement and reporting of hedge ineffectiveness. For cash flow and net investment hedges existing at the date of adoption, the guidance requires entities to apply a cumulative-effect adjustment related to eliminating the separate measurement of ineffectiveness to accumulated other comprehensive income with a corresponding adjustment to the opening balance of retained earnings. Our use of derivative instruments is limited, and we did not recognize an adjustment to retained earnings upon adoption. Given our limited use of derivative instruments, adoption of this guidance did not have a significant impact on our financial statements.