Summary of Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2020
Accounting Policies [Abstract]
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents include cash on hand and cash invested in highly liquid short-term securities, which have remaining maturities at the date of purchase of less than 90 days. Cash and cash equivalents are carried at cost, which approximates fair value.
Goodwill and Other Intangible Assets and Liabilities	Since December 31, 2019, there have been no changes to our accounting polices related to the accounting for goodwill. As of December 31, 2019, no factors were identified that would alter our October 1, 2019 goodwill impairment analysis. During the first quarter of 2020, we concluded that we had a triggering event related to our Fine Arts reporting unit, requiring us to perform an interim goodwill impairment test. The primary factor contributing to our conclusion was the expected impact of the COVID-19 pandemic to this particular business and its customers and revenue sources, which caused us to believe it was more likely than not that the carrying value of our Fine Arts reporting unit exceeded its fair value. During the first quarter of 2020, we performed an interim goodwill impairment test for our Fine Arts reporting unit utilizing a discounted cash flow model, with updated assumptions on future revenues, operating expenditures and capital expenditures. As a result of the interim goodwill impairment test, we concluded that the fair value of our Fine Arts reporting unit was less than its carrying value and, therefore, we recorded a $23,000 impairment charge on the goodwill associated with this reporting unit during the first quarter of 2020. The remaining goodwill for this reporting unit as of March 31, 2020 is approximately $15,000. Factors that may impact these assumptions include, but are not limited to: (i) our ability to maintain, or grow, storage rental and service revenues in line with current expectations and (ii) our ability to manage our fixed and variable costs in line with potential future revenue declines. Finite-lived Intangible Assets and Liabilities Finite-lived intangible assets and liabilities are primarily comprised of customer relationship intangible assets, customer inducements and data center intangible assets and liabilities. Since December 31, 2019, there have been no changes to our accounting policies related to the accounting for any of our finite-lived intangible assets and liabilities as disclosed in Note 2.i. to Notes to Consolidated Financial Statements included in our Annual Report.
Revenues	Data Center Lessor Considerations Our Global Data Center Business features storage rental provided to customers at contractually specified rates over a fixed contractual period, which are accounted for in accordance with ASU 2016-02. Since December 31, 2019, there have been no changes to our accounting policies related to the accounting for our lessor revenue as disclosed in Note 2.l. to Notes to Consolidated Financial Statements included in our Annual Report. Storage rental revenue, including revenue associated with power and connectivity, associated with our Global Data Center Business for the three months ended March 31, 2020 and 2019 are as follow
Accounts Receivable	Accounts Receivable In June 2016, the Financial Accounting Standards Board ("FASB") issued ASU No. 2016-13, Financial Instruments-Credit Losses-Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 changes how entities will measure credit losses on most financial assets. The standard eliminates the probable initial recognition of estimated losses and provides a forward-looking expected credit loss model for accounts receivable, loans and other financial instruments. Prior to our adoption of ASU 2016-13, we maintained an allowance for doubtful accounts for estimated losses resulting from the potential inability of our customers to make required payments and potential disputes regarding billing and service issues. When calculating the allowance, we considered our past loss experience, current and prior trends in our aged receivables and credit memo activity, current economic conditions, and specific circumstances of individual receivable balances. If the financial condition of our customers were to significantly change, resulting in a significant improvement or impairment of their ability to make payments, an adjustment of the allowance might have been required. Additionally, we write off uncollectible balances as circumstances warrant, generally, no later than one year past due. On January 1, 2020 we adopted ASU 2016-13 on a modified retrospective basis for all financial assets measured at amortized cost. The adoption of ASU 2016-13 did not result in a material impact on our consolidated financial statements. In accordance with the guidance in ASU 2016-13, we now calculate and monitor our allowance considering future potential economic and macroeconomic conditions and reasonable and supportable forecasts for expected future collectability of our outstanding receivables, in addition to the factors identified above. Our considerations when calculating our allowance include, but are not limited to, the following: the location of our businesses, the composition of our customer base, our product and service lines, potential future economic unrest, and potential future macroeconomic factors, including natural disasters and any impacts associated with the COVID-19 pandemic. Continued adjustments will be made should there be any material change to reasonable and supportable forecasts that may impact our likelihood of collection, as it becomes evident, including the effects of the COVID-19 pandemic. Our financial assets measured at amortized cost that potentially subject us to credit risk consist predominantly of our accounts receivable. Our highly diverse global customer base, with no single customer accounting for more than 1% of revenue during the three months ended March 31, 2020, limits our exposure to concentration of credit risk. However, the COVID-19 pandemic is impacting numerous industries and geographies globally. We continue to monitor the credit worthiness of our customers, customer payment trends and the adequacy of our bad debt allowance as the COVID-19 pandemic continues.
Leases	Leases We lease facilities for certain of our warehouses, data centers and office space. We also have land leases, including those on which certain of our facilities are located. Since December 31, 2019 there have been no changes to our accounting policies related to the accounting for leases as disclosed in Note 2.m. to Notes to Consolidated Financial Statements included in our Annual Report.
Stock-Based Compensation	Stock-Based Compensation We record stock-based compensation expense, utilizing the straight-line method, for the cost of stock options, restricted stock units ("RSUs"), performance units ("PUs") and shares of stock issued under our employee stock purchase plan (together, "Employee Stock-Based Awards"). There have been no significant changes to our accounting policies, assumptions and valuation methodologies related to the accounting for our Employee Stock-Based Awards as disclosed in Note 2.n. to Notes to Consolidated Financial Statements included in our Annual Report.
Income (Loss) Per Share-Basic and Diluted	Income (Loss) Per Share—Basic and Diluted Basic income (loss) per common share is calculated by dividing income (loss) by the weighted average number of common shares outstanding. The calculation of diluted income (loss) per share is consistent with that of basic income (loss) per share but gives effect to all potential common shares (that is, securities such as stock options, RSUs, PUs, warrants or convertible securities) that were outstanding during the period, unless the effect is antidilutive.
Income Taxes	We provide for income taxes during interim periods based on our estimate of the effective tax rate for the year. Discrete items and changes in our estimate of the annual effective tax rate are recorded in the period they occur. Our effective tax rate is subject to variability in the future due to, among other items: (1) changes in the mix of income between our qualified REIT subsidiaries ("QRSs") and our domestic taxable REIT subsidiaries ("TRSs"), as well as among the jurisdictions in which we operate; (2) tax law changes; (3) volatility in foreign exchange gains and losses; (4) the timing of the establishment and reversal of tax reserves; and (5) our ability to utilize net operating losses that we generate.
Fair Value Measurements	Fair Value Measurements Our financial assets or liabilities that are carried at fair value are required to be measured using inputs from the three levels of the fair value hierarchy as disclosed in Note 2.s. to Notes to Consolidated Financial Statements included in our Annual Report.
Foreign Currency Transactions	The gain or loss on foreign currency transactions, calculated as the difference between the historical exchange rate and the exchange rate at the applicable measurement date, includes gains or losses related to (i) borrowings in certain foreign currencies under our Revolving Credit Facility (as defined and discussed more fully in Note 5), (ii) our Euro Notes (as defined in Note 5) and (iii) certain foreign currency denominated intercompany obligations of our foreign subsidiaries to us and between our foreign subsidiaries, which are not considered permanently invested (as more fully discussed in Note 3).
New Accounting Pronouncements	New Accounting Pronouncements In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which makes a number of changes meant to add, modify or remove certain disclosure requirements associated with the movement of our financial assets and liabilities among the three levels of the fair value hierarchy. We adopted ASU 2018-13 on January 1, 2020. ASU 2018-13 did not have a material impact on our consolidated financial statements. In June 2016, the FASB issued ASU 2016-13. We adopted ASU 2016-13 on January 1, 2020 on a modified retrospective basis. See Note 2.d. for information regarding the impact of the adoption of ASU 2016-13 on our consolidated financial statements.
Correction in Presentation	Change in Presentation We have historically classified our significant acquisition costs which represent operating expenditures associated with (1) the acquisition of Recall Holdings Limited ("Recall") that we completed on May 2, 2016 (the "Recall Transaction"), including: (i) advisory and professional fees to complete the Recall Transaction; (ii) costs associated with the divestments required in connection with receipt of regulatory approvals (including transitional services); and (iii) costs to integrate Recall with our existing operations, including moving, severance, facility upgrade, REIT integration and system upgrade costs, as well as certain costs associated with our shared service center initiative for our finance, human resources and information technology functions; and (2) the advisory and professional fees to complete the acquisition of IODC (collectively, "Significant Acquisition Costs"), as components of Selling, general and administrative expenses and Cost of sales. Beginning in the fourth quarter of 2019, we present Significant Acquisition Costs as its own line item within Operating Expenses in our Condensed Consolidated Statements of Operations. The prior period has been conformed to this presentation.
Aquisitions	We account for acquisitions using the acquisition method of accounting, and, accordingly, the assets and liabilities acquired are recorded at their estimated fair values and the results of operations for each acquisition have been included in our consolidated results from their respective acquisition dates.
Segment Information	The accounting policies of the reportable operating segments are the same as those described in Note 2 and in Note 2 to Notes to Consolidated Financial Statements included in our Annual Report. Adjusted EBITDA for each segment is defined as income (loss) from continuing operations before interest expense, net, provision (benefit) for income taxes, depreciation and amortization, and also excludes certain items that we believe are not indicative of our core operating results, specifically: (1) (gain) loss on disposal/write-down of property, plant and equipment, net (including real estate); (2) intangible impairments; (3) other (income) expense, net (which includes foreign currency transaction (gains) losses, net); (4) Significant Acquisition Costs; and (5) Restructuring Charges (as defined in Note 9). Internally, we use Adjusted EBITDA as the basis for evaluating the performance of, and allocating resources to, our operating segments.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2020

Cash, Cash Equivalents and Restricted Cash

Cash and cash equivalents include cash on hand and cash invested in highly liquid short-term securities, which have remaining maturities at the date of purchase of less than 90 days. Cash and cash equivalents are carried at cost, which approximates fair value.

Goodwill and Other Intangible Assets and Liabilities

Since December 31, 2019, there have been no changes to our accounting polices related to the accounting for goodwill. As of December 31, 2019, no factors were identified that would alter our October 1, 2019 goodwill impairment analysis. During the first quarter of 2020, we concluded that we had a triggering event related to our Fine Arts reporting unit, requiring us to perform an interim goodwill impairment test. The primary factor contributing to our conclusion was the expected impact of the COVID-19 pandemic to this particular business and its customers and revenue sources, which caused us to believe it was more likely than not that the carrying value of our Fine Arts reporting unit exceeded its fair value. During the first quarter of 2020, we performed an interim goodwill impairment test for our Fine Arts reporting unit utilizing a discounted cash flow model, with updated assumptions on future revenues, operating expenditures and capital expenditures. As a result of the interim goodwill impairment test, we concluded that the fair value of our Fine Arts reporting unit was less than its carrying value and, therefore, we recorded a $23,000 impairment charge on the goodwill associated with this reporting unit during the first quarter of 2020. The remaining goodwill for this reporting unit as of March 31, 2020 is approximately $15,000. Factors that may impact these assumptions include, but are not limited to: (i) our ability to maintain, or grow, storage rental and service revenues in line with current expectations and (ii) our ability to manage our fixed and variable costs in line with potential future revenue declines.

Finite-lived Intangible Assets and Liabilities

Finite-lived intangible assets and liabilities are primarily comprised of customer relationship intangible assets, customer inducements and data center intangible assets and liabilities. Since December 31, 2019, there have been no changes to our accounting policies related to the accounting for any of our finite-lived intangible assets and liabilities as disclosed in Note 2.i. to Notes to Consolidated Financial Statements included in our Annual Report.

Revenues

Data Center Lessor Considerations

Our Global Data Center Business features storage rental provided to customers at contractually specified rates over a fixed contractual period, which are accounted for in accordance with ASU 2016-02. Since December 31, 2019, there have been no changes to our accounting policies related to the accounting for our lessor revenue as disclosed in Note 2.l. to Notes to Consolidated Financial Statements included in our Annual Report. Storage rental revenue, including revenue associated with power and connectivity, associated with our Global Data Center Business for the three months ended March 31, 2020 and 2019 are as follow

Accounts Receivable

In June 2016, the Financial Accounting Standards Board ("FASB") issued ASU No. 2016-13, Financial Instruments-Credit Losses-Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 changes how entities will measure credit losses on most financial assets. The standard eliminates the probable initial recognition of estimated losses and provides a forward-looking expected credit loss model for accounts receivable, loans and other financial instruments.

Prior to our adoption of ASU 2016-13, we maintained an allowance for doubtful accounts for estimated losses resulting from the potential inability of our customers to make required payments and potential disputes regarding billing and service issues. When calculating the allowance, we considered our past loss experience, current and prior trends in our aged receivables and credit memo activity, current economic conditions, and specific circumstances of individual receivable balances. If the financial condition of our customers were to significantly change, resulting in a significant improvement or impairment of their ability to make payments, an adjustment of the allowance might have been required. Additionally, we write off uncollectible balances as circumstances warrant, generally, no later than one year past due.

On January 1, 2020 we adopted ASU 2016-13 on a modified retrospective basis for all financial assets measured at amortized cost. The adoption of ASU 2016-13 did not result in a material impact on our consolidated financial statements. In accordance with the guidance in ASU 2016-13, we now calculate and monitor our allowance considering future potential economic and macroeconomic conditions and reasonable and supportable forecasts for expected future collectability of our outstanding receivables, in addition to the factors identified above. Our considerations when calculating our allowance include, but are not limited to, the following: the location of our businesses, the composition of our customer base, our product and service lines, potential future economic unrest, and potential future macroeconomic factors, including natural disasters and any impacts associated with the COVID-19 pandemic. Continued adjustments will be made should there be any material change to reasonable and supportable forecasts that may impact our likelihood of collection, as it becomes evident, including the effects of the COVID-19 pandemic. Our financial assets measured at amortized cost that potentially subject us to credit risk consist predominantly of our accounts receivable. Our highly diverse global customer base, with no single customer accounting for more than 1% of revenue during the three months ended March 31, 2020, limits our exposure to concentration of credit risk. However, the COVID-19 pandemic is impacting numerous industries and geographies globally. We continue to monitor the credit worthiness of our customers, customer payment trends and the adequacy of our bad debt allowance as the COVID-19 pandemic continues.

Leases

We lease facilities for certain of our warehouses, data centers and office space. We also have land leases, including those on which certain of our facilities are located. Since December 31, 2019 there have been no changes to our accounting policies related to the accounting for leases as disclosed in Note 2.m. to Notes to Consolidated Financial Statements included in our Annual Report.

Stock-Based Compensation

We record stock-based compensation expense, utilizing the straight-line method, for the cost of stock options, restricted stock units ("RSUs"), performance units ("PUs") and shares of stock issued under our employee stock purchase plan (together, "Employee Stock-Based Awards"). There have been no significant changes to our accounting policies, assumptions and valuation methodologies related to the accounting for our Employee Stock-Based Awards as disclosed in Note 2.n. to Notes to Consolidated Financial Statements included in our Annual Report.

Income (Loss) Per Share-Basic and Diluted

Income (Loss) Per Share—Basic and Diluted

Basic income (loss) per common share is calculated by dividing income (loss) by the weighted average number of common shares outstanding. The calculation of diluted income (loss) per share is consistent with that of basic income (loss) per share but gives effect to all potential common shares (that is, securities such as stock options, RSUs, PUs, warrants or convertible securities) that were outstanding during the period, unless the effect is antidilutive.

Income Taxes

We provide for income taxes during interim periods based on our estimate of the effective tax rate for the year. Discrete items and changes in our estimate of the annual effective tax rate are recorded in the period they occur. Our effective tax rate is subject to variability in the future due to, among other items: (1) changes in the mix of income between our qualified REIT subsidiaries ("QRSs") and our domestic taxable REIT subsidiaries ("TRSs"), as well as among the jurisdictions in which we operate; (2) tax law changes; (3) volatility in foreign exchange gains and losses; (4) the timing of the establishment and reversal of tax reserves; and (5) our ability to utilize net operating losses that we generate.

Fair Value Measurements

Our financial assets or liabilities that are carried at fair value are required to be measured using inputs from the three levels of the fair value hierarchy as disclosed in Note 2.s. to Notes to Consolidated Financial Statements included in our Annual Report.

Foreign Currency Transactions

The gain or loss on foreign currency transactions, calculated as the difference between the historical exchange rate and the exchange rate at the applicable measurement date, includes gains or losses related to (i) borrowings in certain foreign currencies under our Revolving Credit Facility (as defined and discussed more fully in Note 5), (ii) our Euro Notes (as defined in Note 5) and (iii) certain foreign currency denominated intercompany obligations of our foreign subsidiaries to us and between our foreign subsidiaries, which are not considered permanently invested (as more fully discussed in Note 3).

New Accounting Pronouncements

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which makes a number of changes meant to add, modify or remove certain disclosure requirements associated with the movement of our financial assets and liabilities among the three levels of the fair value hierarchy. We adopted ASU 2018-13 on January 1, 2020. ASU 2018-13 did not have a material impact on our consolidated financial statements.

In June 2016, the FASB issued ASU 2016-13. We adopted ASU 2016-13 on January 1, 2020 on a modified retrospective basis. See Note 2.d. for information regarding the impact of the adoption of ASU 2016-13 on our consolidated financial statements.

Correction in Presentation

Change in Presentation

We have historically classified our significant acquisition costs which represent operating expenditures associated with (1) the acquisition of Recall Holdings Limited ("Recall") that we completed on May 2, 2016 (the "Recall Transaction"), including: (i) advisory and professional fees to complete the Recall Transaction; (ii) costs associated with the divestments required in connection with receipt of regulatory approvals (including transitional services); and (iii) costs to integrate Recall with our existing operations, including moving, severance, facility upgrade, REIT integration and system upgrade costs, as well as certain costs associated with our shared service center initiative for our finance, human resources and information technology functions; and (2) the advisory and professional fees to complete the acquisition of IODC (collectively, "Significant Acquisition Costs"), as components of Selling, general and administrative expenses and Cost of sales. Beginning in the fourth quarter of 2019, we present Significant Acquisition Costs as its own line item within Operating Expenses in our Condensed Consolidated Statements of Operations. The prior period has been conformed to this presentation.

Aquisitions

We account for acquisitions using the acquisition method of accounting, and, accordingly, the assets and liabilities acquired are recorded at their estimated fair values and the results of operations for each acquisition have been included in our consolidated results from their respective acquisition dates.

Segment Information

The accounting policies of the reportable operating segments are the same as those described in Note 2 and in Note 2 to Notes to Consolidated Financial Statements included in our Annual Report. Adjusted EBITDA for each segment is defined as income (loss) from continuing operations before interest expense, net, provision (benefit) for income taxes, depreciation and amortization, and also excludes certain items that we believe are not indicative of our core operating results, specifically: (1) (gain) loss on disposal/write-down of property, plant and equipment, net (including real estate); (2) intangible impairments; (3) other (income) expense, net (which includes foreign currency transaction (gains) losses, net); (4) Significant Acquisition Costs; and (5) Restructuring Charges (as defined in Note 9). Internally, we use Adjusted EBITDA as the basis for evaluating the performance of, and allocating resources to, our operating segments.