Mobile Mini, Inc. - Organization and Description of Business (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The consolidated financial statements include the accounts of Mobile Mini and our wholly owned subsidiaries. We do not have any subsidiaries in which we do not own 100% of the outstanding stock. All significant intercompany balances and transactions have been eliminated. The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) applicable to interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all the information and footnotes required by GAAP for complete financial statements. In the opinion of management of Mobile Mini, all adjustments (which include normal recurring adjustments) necessary to present fairly the financial position, results of operations, and cash flows for all periods presented have been made. The results of operations for the three and nine months ended September 30, 2018 and 2017, respectively, are not necessarily indicative of the results to be expected for the full year. During the current year, we changed the classification of certain ancillary revenues that were previously reported in rental and other revenues to sales revenues, and the corresponding expenses are now being classified in cost of sales on the accompanying condensed consolidated statements of operations for the three and nine months ended September 30, 2018. As the amounts are immaterial, reclassifications were not made in the corresponding period of the prior year. These condensed consolidated financial statements should be read in conjunction with our audited consolidated financial statements and accompanying notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2017 filed with the Securities and Exchange Commission (“SEC”) on February 2, 2018.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying condensed consolidated financial statements and the notes to those statements. Actual results could differ from those estimates. Significant estimates affect the calculation of depreciation and amortization, the calculation of the allowance for doubtful accounts, the analysis of goodwill and long-lived assets for potential impairment and certain accrued liabilities.
Fair Value Measurements	Fair value is the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value is a market-based measurement determined by assumptions that market participants would use in pricing an asset or liability. We categorize each of our fair value measurements in one of the following three levels based on the lowest level of input that is significant to the fair value measurement: Level 1 — Observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2 — Observable inputs, other than Level 1 inputs in active markets, that are observable either directly or indirectly; and Level 3 — Unobservable inputs for which there is little or no market data, which require the reporting entity to develop its own assumptions.
Earnings Per Share	Basic earnings per share (“EPS”) is calculated by dividing net income by the weighted average number of common shares outstanding during the period. Restricted stock awards are subject to the risk of forfeiture and are not included in the calculation of basic weighted average number of common shares outstanding until vested. Diluted EPS is calculated under the treasury stock method. Potential common shares included restricted common stock and incremental shares of common stock issuable upon the exercise of stock options.
Inventories	Inventories are valued at the lower of cost (principally on a standard cost basis which approximates the first-in, first-out method) or net realizable value. Raw materials and supplies principally consist of raw steel, glass, paint, vinyl and other assembly components used in manufacturing and remanufacturing processes and, to a lesser extent, parts used for internal maintenance and ancillary items held for sale in our Tank & Pump Solutions segment. Work-in-process primarily represents partially assembled units. Finished units primarily represent purchased or assembled containers held in inventory until the container is either sold as is, remanufactured and sold, or remanufactured and deployed as rental fleet.
Property, Plant and Equipment	Property, plant and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is recorded using the straight-line method over the assets’ estimated useful lives. Our depreciation expense related to property, plant and equipment for the nine months ended September 30, 2018 and 2017 was $21.4 million and $19.0 million, respectively. Normal repairs and maintenance to property, plant and equipment are expensed as incurred. When property or equipment is retired or sold, the net book value of the asset, reduced by any proceeds, is charged to gain or loss on the disposal of property, plant and equipment and is included in rental, selling and general expenses in the condensed consolidated statements of operations.
Segment Reporting, Policy	Our operations are comprised of three reportable segments: North American Storage Solutions, U.K. Storage Solutions and Tank & Pump Solutions. Discrete financial data on each of our products is not available and it would be impractical to collect and maintain financial data in such a manner. The results for each segment are reviewed discretely by our chief operating decision maker. We operate in the U.S., the U.K. and Canada. All of our locations operate in their local currency. Although we are exposed to foreign exchange rate fluctuation in foreign markets where we rent and sell our products, we do not believe such exposure will have a significant impact on our results of operations. Revenues recognized by our U.S. locations were $125.8 million and $113.1 million for the three months ended September 30, 2018 and 2017, respectively, and were $362.0 million and $320.5 million for the nine months ended September 30, 2018 and 2017, respectively.
Impact of Recently Issued Accounting Standards	Impact of Recently Issued Accounting Standards Intangibles – Goodwill and Other – Internal-Use Software. In August 2018, the Financial Accounting Standards Board (“FASB”) issued a standard that provides guidance on accounting for implementation costs incurred in a cloud computing arrangement that is a service contract. The amendments in this update align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software, and hosting arrangements that include an internal-use software license. This guidance also requires entities to present the expense related to the capitalized implementation costs in the same line item in the statement of income as the fees associated with the hosting element (service) of the arrangement and classify payments for capitalized implementation costs in the statement of cash flows in the same manner as payments made for fees associated with the hosting element. The entity is also required to present the capitalized implementation costs in the statement of financial position in the same line item that a prepayment for the fees of the associated hosting arrangement would be presented. This standard is effective for annual and interim periods beginning after December 15, 2019. We are currently evaluating the effect the standard will have on our financial statements. Share-Based Compensation – Modifications. In May 2017, the FASB issued a standard which clarifies what constitutes a modification of a share-based payment award. This standard is effective for annual and interim periods beginning after December 15, 2017. We implemented this standard on January 1, 2018 and will apply the guidance to future modifications. Business Combinations. In January 2017, the FASB issued a standard which clarifies the definition of a business and provides a new framework for determining whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. This standard is effective for annual and interim periods beginning after December 15, 2017. We implemented this standard on January 1, 2018 and will apply the guidance to future transactions. Intangibles – Goodwill and Other. In January 2017, the FASB issued a standard requiring an entity to no longer perform a hypothetical purchase price allocation to measure goodwill impairment. Instead, impairment will be measured using the difference between the carrying amount and the fair value of the reporting unit. This standard is effective for annual and interim periods beginning after December 15, 2019. Entities may early adopt the guidance. We have not determined an adoption date and do not expect the adoption of this standard to have a material effect on our consolidated financial statements. Leases. In February 2016, the FASB issued a standard on lease accounting requiring a lessee to recognize assets and liabilities on the balance sheet for leases with lease terms greater than 12 months. This standard is effective for annual and interim periods beginning after December 15, 2018. We expect to adopt this standard effective January 1, 2019. A modified retrospective transition approach is required. Entities may choose between applying the new standard as of the date of initial application, or applying the standard to all leases existing as of the earliest comparative period and recasting its comparative period financial statements. We expect to use the effective date as our date of initial application. Consequently, financial information will not be updated and the disclosures required under the new standard will not be provided for dates and periods before January 1, 2019. While we are continuing to evaluate all potential impacts of the standard, we do not believe the accounting for our contractual rental revenue will be materially affected by the adoption of this standard. The standard includes optional transition practical expedients intended to simplify its adoption. We intend to elect to use certain of these expedients including, among other things, the ability to retain lease classification determined under legacy GAAP as well as a relief from reviewing expired or existing contracts to determine if they contain leases. We anticipate the lessee accounting for operating leases under the standard will have a material effect on our statement of financial position. Upon adoption, we currently expect to recognize additional operating liabilities totaling between $75 million to $85 million, with corresponding right of use assets. The liabilities will be calculated as the present value of the remaining minimum rental payments for existing operating leases. Revenue from Contracts with Customers. In May 2014, the FASB issued an accounting standard on revenue from contracts with customers. The standard provides a single model for revenue arising from contracts with customers and supersedes previous revenue recognition guidance. The standard requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of goods or services and is effective for annual and interim periods beginning after December 15, 2017. We adopted this guidance with a date of initial application of January 1, 2018. The majority of our revenue, as it relates to contractual rental revenue, is excluded from the scope of this standard, and the accounting for the remaining revenue streams were not affected. We utilized the modified retrospective adoption and there was no impact on our consolidated financial statements, nor was there a cumulative effect of initially applying the standard. For more information regarding our revenue from contracts with customers, see the disclosure in Note 4.
Rental Fleet, Policy	Rental fleet is capitalized at cost and depreciated over the estimated useful life of the unit using the straight-line method. Rental fleet is depreciated whether or not it is out on rent. Capitalized cost of rental fleet includes the price paid to acquire the unit and freight charges to the location when the unit is first placed in service, and when applicable, the cost of manufacturing or remanufacturing, which includes the cost of customizing units. Ordinary repair and maintenance costs are charged to operations as incurred. We periodically review depreciable lives and residual values against various factors, including the results of our lenders’ independent appraisal of our rental fleet, practices of our competitors in comparable industries and profit margins achieved on sales of depreciated units.