Summary of Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2017
Accounting Policies [Abstract]
Principals of Consolidation	Principles of Consolidation The accompanying financial statements reflect our financial position, results of operations, comprehensive income (loss), equity and cash flows on a consolidated basis. All intercompany transactions and account balances have been eliminated.
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.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP") requires us to make estimates, judgments and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities at the date of the financial statements and for the period then ended. On an ongoing basis, we evaluate the estimates used. We base our estimates on historical experience, actuarial estimates, current conditions and various other assumptions that we believe to be reasonable under the circumstances. These estimates form the basis for making judgments about the carrying values of assets and liabilities and are not readily apparent from other sources. Actual results may differ from these estimates.
Derivatives Instruments and Hedging Activities	Derivative Instruments and Hedging Activities Every derivative instrument is required to be recorded in the balance sheet as either an asset or a liability measured at its fair value. Periodically, we acquire derivative instruments that are intended to hedge either cash flows or values that are subject to foreign exchange or other market price risk and not for trading purposes. We have formally documented our hedging relationships, including identification of the hedging instruments and the hedged items, as well as our risk management objectives and strategies for undertaking each hedge transaction.
Property, Plant and Equipment	Entities are required to record the fair value of a liability for an asset retirement obligation in the period in which it is incurred. Asset retirement obligations represent the costs to replace or remove tangible long-lived assets required by law, regulatory rule or contractual agreement. When the liability is initially recorded, the entity capitalizes the cost by increasing the carrying amount of the related long-lived asset, which is then depreciated over the useful life of the related asset. The liability is increased over time through accretion expense (included in depreciation expense) such that the liability will equate to the future cost to retire the long-lived asset at the expected retirement date. Upon settlement of the liability, an entity either settles the obligation for its recorded amount or realizes a gain or loss upon settlement. Our asset retirement obligations are primarily the result of requirements under our facility lease agreements which generally have "return to original condition" clauses which would require us to remove or restore items such as shred pits, vaults, demising walls and office build-outs, among others. The significant assumptions used in estimating our aggregate asset retirement obligation are the timing of removals, the probability of a requirement to perform, estimated cost and associated expected inflation rates that are consistent with historical rates and credit-adjusted risk-free rates that approximate our incremental borrowing rate. Minor maintenance costs are expensed as incurred. Major improvements which extend the life, increase the capacity or improve the safety or the efficiency of property owned are capitalized. Major improvements to leased buildings are capitalized as leasehold improvements and depreciated. We develop various software applications for internal use. Computer software costs associated with internal use software are expensed as incurred until certain capitalization criteria are met. Payroll and related costs for employees directly associated with, and devoting time to, the development of internal use computer software projects (to the extent time is spent directly on the project) are capitalized. Capitalization begins when the design stage of the application has been completed and it is probable that the project will be completed and used to perform the function intended. Capitalization ends when the asset is ready for its intended use. Depreciation begins when the software is placed in service. Computer software costs that are capitalized are periodically evaluated for impairment.
Goodwill and Other Intangible Assets	Reporting unit valuations have generally been determined using a combined approach based on the present value of future cash flows and market multiples. The income approach incorporates many assumptions including future growth rates and operating margins, discount rate factors, expected capital expenditures and income tax cash flows. Changes in economic and operating conditions impacting these assumptions could result in goodwill impairments in future periods. In conjunction with our annual goodwill impairment reviews, we reconcile the sum of the valuations of all of our reporting units to our market capitalization as of such dates. Goodwill and intangible assets with indefinite lives are not amortized but are reviewed annually for impairment or more frequently if impairment indicators arise. Other than goodwill, we currently have no intangible assets that have indefinite lives and which are not amortized. We have selected October 1 as our annual goodwill impairment review date.
Customer Relationships and Acquisitions Costs and Other Intangible Assets	Customer relationship intangible assets, which are acquired through either business combinations or acquisitions of customer relationships, are amortized over periods ranging from ten to 30 years (weighted average of 18 years at December 31, 2017). The value of customer relationship intangible assets is calculated based upon estimates of their fair value utilizing an income approach based on the present value of expected future cash flows. Costs related to the acquisition of large volume accounts are capitalized. Free intake costs to transport boxes to one of our facilities, which include labor and transportation costs ("Move Costs"), are amortized over periods ranging from ten to 30 years (weighted average of 26 years as of December 31, 2017), and are included in depreciation and amortization in the accompanying Consolidated Statements of Operations. Payments that are made to a customer's current records management vendor in order to terminate the customer's existing contract with that vendor, or direct payments to a customer ("Permanent Withdrawal Fees"), are amortized over periods ranging from five to 15 years (weighted average of seven years as of December 31, 2017), and are included in storage and service revenue in the accompanying Consolidated Statements of Operations. Move Costs and Permanent Withdrawal Fees are collectively referred to as "Customer Inducements". If the customer terminates its relationship with us, the unamortized carrying value of the Customer Inducement intangible asset is charged to expense or revenue. However, in the event of such termination, we generally collect, and record as income, permanent removal fees that generally equal or exceed the amount of the unamortized Customer Inducement intangible asset. Other finite-lived intangible assets, including trade names, noncompetition agreements and trademarks, are capitalized and amortized over a weighted average of four years as of December 31, 2017, and are included in depreciation and amortization in the accompanying Consolidated Statements of Operations.
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs are amortized over the life of the related debt using the effective interest rate method. If debt is retired early, the related unamortized deferred financing costs are written-off in the period the debt is retired to other expense (income), net.
Revenues	Revenues Our revenues consist of storage rental revenues as well as service revenues and are reflected net of sales and value added taxes. Storage rental revenues, which are considered a key driver of financial performance for the storage and information management services industry, consist primarily of recurring periodic rental charges related to the storage of materials or data (generally on a per unit basis) and technology escrow services that protect and manage source code. Service revenues include charges for related service activities, which include: (1) the handling of records, including the addition of new records, temporary removal of records from storage, refiling of removed records and the destruction of records; (2) courier operations, consisting primarily of the pickup and delivery of records upon customer request; (3) secure shredding of sensitive documents and the related sale of recycled paper, the price of which can fluctuate from period to period; (4) other services, including the scanning, imaging and document conversion services of active and inactive records ("Information Governance and Digital Solutions") which relate to physical and digital records, and project revenues; (5) customer termination and permanent removal fees; (6) data restoration projects; (7) special project work; (8) the storage, assembly, reporting and delivery of customer marketing literature, or fulfillment services; (9) consulting services; (10) cloud-related data protection, preservation, restoration and recovery; and (11) other technology services and product sales (including specially designed storage containers and related supplies). We recognize revenue when the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) services have been rendered; (3) the sales price is fixed or determinable; and (4) collectability of the resulting receivable is reasonably assured. Storage rental and service revenues are recognized in the month the respective storage rental or service is provided, and customers are generally billed on a monthly basis on contractually agreed-upon terms. Amounts related to future storage rental or prepaid service contracts for customers where storage rental fees or services are billed in advance are accounted for as deferred revenue and recognized ratably over the period the applicable storage rental or service is provided or performed. Revenues from the sales of products, which are included as a component of service revenues, are recognized when products are shipped and title has passed to the customer. Revenues from the sales of products, which represented less than 2% of consolidated revenue for the year ended December 31, 2017, have historically not been significant. In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). ASU 2014-09 provides guidance for management to reassess revenue recognition as it relates to: (1) transfer of control, (2) variable consideration, (3) allocation of transaction price based on relative standalone selling price, (4) licenses, (5) time value of money, and (6) contract costs. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date ("ASU 2015-14"). ASU 2015-14 deferred the effective date of ASU 2014-09 for one year, making it effective for us on January 1, 2018, with early adoption permitted as of January 1, 2017. We will adopt ASU 2014-09 as of January 1, 2018. See Note 2.w. for additional information on ASU 2014-09.
Rent Normalization	We have entered into various leases for buildings that expire over various terms. Certain leases have fixed escalation clauses (excluding those tied to the consumer price index or other inflation-based indices) or other features (including return to original condition, primarily in the United Kingdom) which require normalization of the rental expense over the life of the lease, resulting in deferred rent being reflected as a liability in the accompanying Consolidated Balance Sheets. In addition, we have assumed various above and below market leases in connection with certain of our acquisitions. The difference between the present value of these lease obligations and the market rate at the date of the acquisition was recorded as either a deferred rent liability (which is a component of Other Long-Term Liabilities) or deferred rent asset (which is a component of Other within Other Assets, net) in our Consolidated Balance Sheets and is being amortized to rent expense.
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 ("ESPP") (together, "Employee Stock-Based Awards"). Our equity compensation plans generally provide that any unvested options and other awards granted thereunder shall vest immediately if an employee is terminated, or terminates their own employment for good reason (as defined in each plan), in connection with a vesting change in control (as defined in each plan). On January 20, 2015, our stockholders approved the adoption of the Iron Mountain Incorporated 2014 Stock and Cash Incentive Plan, as amended (the "2014 Plan"). The majority of our PUs are earned based on our performance against revenue and ROIC targets during their applicable performance period, therefore, we forecast the likelihood of achieving the predefined revenue and ROIC targets in order to calculate the expected PUs to be earned. We record a compensation charge based on either the forecasted PUs to be earned (during the performance period) or the actual PUs earned (at the three-year anniversary date of the grant date) over the vesting period for each of the awards. The fair value of PUs based on our performance against revenue and ROIC targets is the excess of the market price of our common stock at the date of grant over the purchase price (which is typically zero). For PUs earned based on a market condition, we utilize a Monte Carlo simulation to fair value these awards at the date of grant, and such fair value is expensed over the three-year performance period. Performance Units Under our various equity compensation plans, we may also make awards of PUs. For the majority of outstanding PUs, the number of PUs earned is determined based on our performance against predefined targets of revenue and return on invested capital ("ROIC"). The number of PUs earned may range from 0% to 200% of the initial award. The number of PUs earned is determined based on our actual performance as compared to the targets at the end of a three-year performance period. Certain PUs that we grant will be earned based on a market condition associated with the total return on our common stock in relation to a subset of the Standard & Poor's 500 Index rather than the revenue and ROIC targets noted above. The number of PUs earned based on this market condition may range from 0% to 200% of the initial award. All of our PUs will be settled in shares of our common stock and are subject to cliff vesting three years from the date of the original PU grant. PUs awarded to employees who terminate their employment during the three-year performance period and on or after attaining age 55 and completing 10 years of qualifying service are eligible for pro-rated vesting, subject to the actual achievement against the predefined targets or a market condition as discussed above, based on the number of full years of service completed following the grant date (but delivery of the shares remains deferred). As a result, PUs are generally expensed over the three-year performance period. All PUs accrue dividend equivalents associated with the underlying stock as we declare dividends. Dividends will generally be paid to holders of PUs in cash upon the settlement date of the associated PU and will be forfeited if the PU does not vest. We offer an ESPP in which participation is available to substantially all United States and Canadian employees who meet certain service eligibility requirements. The ESPP provides a way for our eligible employees to become stockholders on favorable terms. The ESPP provides for the purchase of our common stock by eligible employees through successive offering periods. We have historically had two six-month offering periods per year, the first of which generally runs from June 1 through November 30 and the second of which generally runs from December 1 through May 31. During each offering period, participating employees accumulate after-tax payroll contributions, up to a maximum of 15% of their compensation, to pay the purchase price at the end of the offering. Participating employees may withdraw from an offering before the purchase date and obtain a refund of the amounts withheld as payroll deductions. At the end of the offering period, outstanding options under the ESPP are exercised, and each employee's accumulated contributions are used to purchase our common stock. The price for shares purchased under the ESPP is 95% of the fair market price at the end of the offering period, without a look-back feature. As a result, we do not recognize compensation expense for the ESPP shares purchased. Expected volatility is calculated utilizing daily historical volatility over a period that equates to the expected life of the option. The risk-free interest rate was based on the United States Treasury interest rates whose term is consistent with the expected life (estimated period of time outstanding) of the stock options. Expected dividend yield is considered in the option pricing model and represents our current annualized expected per share dividends over the current trade price of our common stock. The expected life of the stock options granted is estimated using the historical exercise behavior of employees. Under our various equity compensation plans, we may also grant RSUs. Our RSUs generally have a vesting period of three years from the date of grant. However, RSUs granted to our non-employee directors in 2015 and thereafter vest immediately upon grant. All RSUs accrue dividend equivalents associated with the underlying stock as we declare dividends. Dividends will generally be paid to holders of RSUs in cash upon the vesting date of the associated RSU and will be forfeited if the RSU does not vest. The fair value of RSUs is the excess of the market price of our common stock at the date of grant over the purchase price (which is typically zero). Stock Options Under our various stock option plans, options are generally granted with exercise prices equal to the market price of the stock on the date of grant; however, in certain instances, options are granted at prices greater than the market price of the stock on the date of grant. The options we issue become exercisable ratably over a period of either (i) three years from the date of grant and have a contractual life of ten years from the date of grant, unless the holder's employment is terminated sooner, (ii) five years from the date of grant and have a contractual life of ten years from the date of grant, unless the holder's employment is terminated sooner, or (iii) ten years from the date of grant and have a contractual life of 12 years from the date of grant, unless the holder's employment is terminated sooner. Our non-employee directors are considered employees for purposes of our stock option plans and stock option reporting.
Income Taxes	Accounting for income taxes requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the tax and financial reporting bases of assets and liabilities and for loss and credit carryforwards. Valuation allowances are provided when recovery of deferred tax assets does not meet the more likely than not standard as defined in GAAP. We have elected to recognize interest and penalties associated with uncertain tax positions as a component of the (benefit) provision for income taxes in the accompanying Consolidated Statements of Operations.
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.
Allowance for Doubtful Accounts and Credit Memo Reserves	We maintain an allowance for doubtful accounts and credit memos 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 consider 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 may be required. We charge-off uncollectible balances as circumstances warrant, generally, no later than one year past due.
Fair Value Measurements	Entities are permitted under GAAP to elect to measure many financial instruments and certain other items at either fair value or cost. We have elected the cost measurement option. 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. A financial asset or liability's classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. The three levels of the fair value hierarchy are as follows: Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access at the measurement date. Level 2—Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs). Level 3—Unobservable inputs that reflect our assumptions about the assumptions that market participants would use in pricing the asset or liability.
New Accounting Pronouncements	New Accounting Pronouncements Recently Adopted Accounting Pronouncements In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ("ASU 2017-04"). ASU 2017-04 modifies the process by which entities will test goodwill for impairment. Under existing GAAP, when the carrying value of a reporting unit exceeds the reporting unit’s fair value, an entity would then proceed to a “Step 2” goodwill impairment analysis, which requires calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities, as if that reporting unit had been acquired in a business combination. Under ASU 2017-04, a goodwill impairment will be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying value of the reporting unit’s goodwill. We adopted ASU 2017-04 in the first quarter of 2017. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business ("ASU 2017-01"). ASU 2017-01 provides greater clarity on the definition of a business to assist entities in evaluating whether transactions should be accounted for as an acquisition or disposal of assets or businesses. We adopted ASU 2017-01 in the third quarter of 2017. ASU 2017-01 did not have a material impact on our consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a Consensus of the FASB Emerging Issues Task Force) ("ASU 2016-18"). ASU 2016-18 requires that restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the cash and cash equivalents as of the beginning of the period to the cash and cash equivalents as of the end of the period in the statement of cash flows. We adopted ASU 2016-18 during the fourth quarter of 2017 retrospectively for the earliest year presented in our consolidated statement of cash flows. ASU 2016-18 did not have a material impact on our consolidated financial statements. As Yet Adopted Accounting Pronouncements a. ASU 2014-09 In May 2014, the FASB issued ASU No. 2014-09. ASU 2014-09 provides guidance for revenue recognition as it relates to: (1) transfer of control, (2) variable consideration, (3) allocation of transaction price based on relative standalone selling price, (4) licenses, (5) time value of money, and (6) contract costs. ASU 2014-09 will replace the current revenue recognition criteria under GAAP, including industry-specific requirements, and provide companies with a single revenue recognition model for recognizing revenue from contracts with customers. The core principle of ASU 2014-09 is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for such goods or services. The two permitted transition methods under ASU 2014-09 are: (i) the full retrospective method, whereby ASU 2014-09 would be applied to each prior reporting period presented and the cumulative effect of adoption would be recognized at the earliest period shown, or (ii) the modified retrospective method, whereby the cumulative effect of applying ASU 2014-09 would be recognized at the date of initial application. In August 2015, the FASB issued ASU No. 2015-14, which deferred the effective date of ASU 2014-09 for one year, making ASU 2014-09 effective for us on January 1, 2018, with early adoption permitted as of January 1, 2017. We will adopt ASU 2014-09 as of January 1, 2018 using the modified retrospective method. i. Accounting for Commissions Under current GAAP, commissions that we pay related to our long-term storage contracts are expensed as incurred. Under ASU 2014-09, however, certain commissions will be capitalized and amortized over the period of expected earned revenue. In the year of adoption, this will result in increased contract assets on our Consolidated Balance Sheet, a reduction in selling, general and administrative expenses and a corresponding increase in amortization expense (assuming consistent levels of spending up through the adoption date) on our Consolidated Statement of Operations and an increase in cash flows from operating activities and a corresponding increase in cash used for investing activities on our Consolidated Statement of Cash Flows. b. Other As Yet Adopted Accounting Pronouncements In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"). ASU 2016-01 requires that most equity investments be measured at fair value, with subsequent changes in fair value recognized in net income, while eliminating the available-for-sale classification for equity securities with readily determinable fair values and the cost method for equity investments without readily determinable fair values. ASU 2016-01 also impacts financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. ASU 2016-01 is effective for us on January 1, 2018. We will adopt ASU 2016-01 on January 1, 2018 and are currently evaluating the impact ASU 2016-01 will have on our consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"). ASU 2016-02 requires lessees to recognize assets and liabilities on the balance sheet for the rights and obligations created by all leases with terms of more than 12 months. ASU 2016-02 also will require certain qualitative and quantitative disclosures designed to give financial statement users information on the amount, timing, and uncertainty of cash flows arising from leases. ASU 2016-02 will be effective for us on January 1, 2019, with early adoption permitted. We will adopt ASU 2016-02 on January 1, 2019 and are currently evaluating the impact ASU 2016-02 will have on our consolidated financial statements. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"). ASU 2017-12 amends the hedge accounting recognition and presentation requirements as outlined in Accounting Standards Codification Topic 815 with the objective of improving the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements and enhance the transparency and understandability of hedge transactions. In addition, ASU 2017-12 simplifies the application of the hedge accounting guidance. ASU 2017-12 is effective for us on January 1, 2019, with early adoption permitted. We are currently evaluating the impact ASU 2017-12 will have on our consolidated financial statements. ii. Accounting for Initial Moves Under current GAAP, intake costs incurred but not charged to a customer to transport records to our facilities, which include labor and transportation costs, are capitalized and amortized as a component of depreciation and amortization in our Consolidated Statements of Operations. Under ASU 2014-09, however, the revenue and costs associated with all initial moves of physical storage, regardless of whether or not the services associated with such initial moves are provided to the customer at no charge, will be deferred and recognized over the period consistent with the transfer of the service to the customer to which the asset relates. In the year of adoption, this will result in decreased assets and increased deferred revenue on our Consolidated Balance Sheet, a reduction in cost of sales and a corresponding increase in amortization expense (assuming consistent levels of initial move spending through the adoption date) on our Consolidated Statement of Operations and an increase in cash flows from operating activities and a corresponding increase in cash used for investing activities on our Consolidated Statement of Cash Flows. Redeemable Noncontrolling Interests Certain unaffiliated third parties own noncontrolling interests in our consolidated subsidiaries in Chile, India and South Africa. The underlying shareholder agreements between us and our noncontrolling interest shareholders for these subsidiaries contain provisions under which the noncontrolling interest shareholders can require us to purchase their respective interests in such subsidiaries at certain times and at a purchase price as stipulated in the underlying shareholder agreements (generally at fair value). These put options make these noncontrolling interests redeemable and, therefore, these noncontrolling interests are classified as temporary equity outside of stockholders' equity. Redeemable noncontrolling interests are reported at the higher of their redemption value or the noncontrolling interest holders' proportionate share of the underlying subsidiaries net carrying value. Increases or decreases in the redemption value of the noncontrolling interest are offset against Additional Paid-in Capital.
Long-Lived Assets	We review long-lived assets, including all finite-lived intangible assets, for impairment whenever events or changes in circumstances indicate the carrying amount of such assets may not be recoverable. Recoverability of these assets is determined by comparing the forecasted undiscounted net cash flows of the operation to which the assets relate to their carrying amount. The operations are generally distinguished by the business segment and geographic region in which they operate. If it is determined that we are unable to recover the carrying amount of the assets, the long-lived assets are written down, on a pro rata basis, to fair value. Fair value is determined based on discounted cash flows or appraised values, depending upon the nature of the assets. Long-lived assets, including finite-lived intangible assets, are amortized over their useful lives. Annually, or more frequently if events or circumstances warrant, we assess whether a change in the lives over which long-lived assets, including finite-lived intangible assets, are amortized is necessary.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Principles of Consolidation

The accompanying financial statements reflect our financial position, results of operations, comprehensive income (loss), equity and cash flows on a consolidated basis. All intercompany transactions and account balances have been eliminated.

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.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP") requires us to make estimates, judgments and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities at the date of the financial statements and for the period then ended. On an ongoing basis, we evaluate the estimates used. We base our estimates on historical experience, actuarial estimates, current conditions and various other assumptions that we believe to be reasonable under the circumstances. These estimates form the basis for making judgments about the carrying values of assets and liabilities and are not readily apparent from other sources. Actual results may differ from these estimates.

Derivatives Instruments and Hedging Activities

Derivative Instruments and Hedging Activities

Every derivative instrument is required to be recorded in the balance sheet as either an asset or a liability measured at its fair value. Periodically, we acquire derivative instruments that are intended to hedge either cash flows or values that are subject to foreign exchange or other market price risk and not for trading purposes. We have formally documented our hedging relationships, including identification of the hedging instruments and the hedged items, as well as our risk management objectives and strategies for undertaking each hedge transaction.

Property, Plant and Equipment

Entities are required to record the fair value of a liability for an asset retirement obligation in the period in which it is incurred. Asset retirement obligations represent the costs to replace or remove tangible long-lived assets required by law, regulatory rule or contractual agreement. When the liability is initially recorded, the entity capitalizes the cost by increasing the carrying amount of the related long-lived asset, which is then depreciated over the useful life of the related asset. The liability is increased over time through accretion expense (included in depreciation expense) such that the liability will equate to the future cost to retire the long-lived asset at the expected retirement date. Upon settlement of the liability, an entity either settles the obligation for its recorded amount or realizes a gain or loss upon settlement. Our asset retirement obligations are primarily the result of requirements under our facility lease agreements which generally have "return to original condition" clauses which would require us to remove or restore items such as shred pits, vaults, demising walls and office build-outs, among others. The significant assumptions used in estimating our aggregate asset retirement obligation are the timing of removals, the probability of a requirement to perform, estimated cost and associated expected inflation rates that are consistent with historical rates and credit-adjusted risk-free rates that approximate our incremental borrowing rate.

Minor maintenance costs are expensed as incurred. Major improvements which extend the life, increase the capacity or improve the safety or the efficiency of property owned are capitalized. Major improvements to leased buildings are capitalized as leasehold improvements and depreciated.

We develop various software applications for internal use. Computer software costs associated with internal use software are expensed as incurred until certain capitalization criteria are met. Payroll and related costs for employees directly associated with, and devoting time to, the development of internal use computer software projects (to the extent time is spent directly on the project) are capitalized.

Capitalization begins when the design stage of the application has been completed and it is probable that the project will be completed and used to perform the function intended. Capitalization ends when the asset is ready for its intended use. Depreciation begins when the software is placed in service. Computer software costs that are capitalized are periodically evaluated for impairment.

Goodwill and Other Intangible Assets

Reporting unit valuations have generally been determined using a combined approach based on the present value of future cash flows and market multiples. The income approach incorporates many assumptions including future growth rates and operating margins, discount rate factors, expected capital expenditures and income tax cash flows. Changes in economic and operating conditions impacting these assumptions could result in goodwill impairments in future periods. In conjunction with our annual goodwill impairment reviews, we reconcile the sum of the valuations of all of our reporting units to our market capitalization as of such dates.

Goodwill and intangible assets with indefinite lives are not amortized but are reviewed annually for impairment or more frequently if impairment indicators arise. Other than goodwill, we currently have no intangible assets that have indefinite lives and which are not amortized.

We have selected October 1 as our annual goodwill impairment review date.

Customer Relationships and Acquisitions Costs and Other Intangible Assets

Customer relationship intangible assets, which are acquired through either business combinations or acquisitions of customer relationships, are amortized over periods ranging from ten to 30 years (weighted average of 18 years at December 31, 2017). The value of customer relationship intangible assets is calculated based upon estimates of their fair value utilizing an income approach based on the present value of expected future cash flows.

Costs related to the acquisition of large volume accounts are capitalized. Free intake costs to transport boxes to one of our facilities, which include labor and transportation costs ("Move Costs"), are amortized over periods ranging from ten to 30 years (weighted average of 26 years as of December 31, 2017), and are included in depreciation and amortization in the accompanying Consolidated Statements of Operations. Payments that are made to a customer's current records management vendor in order to terminate the customer's existing contract with that vendor, or direct payments to a customer ("Permanent Withdrawal Fees"), are amortized over periods ranging from five to 15 years (weighted average of seven years as of December 31, 2017), and are included in storage and service revenue in the accompanying Consolidated Statements of Operations. Move Costs and Permanent Withdrawal Fees are collectively referred to as "Customer Inducements". If the customer terminates its relationship with us, the unamortized carrying value of the Customer Inducement intangible asset is charged to expense or revenue. However, in the event of such termination, we generally collect, and record as income, permanent removal fees that generally equal or exceed the amount of the unamortized Customer Inducement intangible asset.

Other finite-lived intangible assets, including trade names, noncompetition agreements and trademarks, are capitalized and amortized over a weighted average of four years as of December 31, 2017, and are included in depreciation and amortization in the accompanying Consolidated Statements of Operations.

Deferred Financing Costs

Deferred financing costs are amortized over the life of the related debt using the effective interest rate method. If debt is retired early, the related unamortized deferred financing costs are written-off in the period the debt is retired to other expense (income), net.

Revenues

Our revenues consist of storage rental revenues as well as service revenues and are reflected net of sales and value added taxes. Storage rental revenues, which are considered a key driver of financial performance for the storage and information management services industry, consist primarily of recurring periodic rental charges related to the storage of materials or data (generally on a per unit basis) and technology escrow services that protect and manage source code. Service revenues include charges for related service activities, which include: (1) the handling of records, including the addition of new records, temporary removal of records from storage, refiling of removed records and the destruction of records; (2) courier operations, consisting primarily of the pickup and delivery of records upon customer request; (3) secure shredding of sensitive documents and the related sale of recycled paper, the price of which can fluctuate from period to period; (4) other services, including the scanning, imaging and document conversion services of active and inactive records ("Information Governance and Digital Solutions") which relate to physical and digital records, and project revenues; (5) customer termination and permanent removal fees; (6) data restoration projects; (7) special project work; (8) the storage, assembly, reporting and delivery of customer marketing literature, or fulfillment services; (9) consulting services; (10) cloud-related data protection, preservation, restoration and recovery; and (11) other technology services and product sales (including specially designed storage containers and related supplies).

We recognize revenue when the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) services have been rendered; (3) the sales price is fixed or determinable; and (4) collectability of the resulting receivable is reasonably assured. Storage rental and service revenues are recognized in the month the respective storage rental or service is provided, and customers are generally billed on a monthly basis on contractually agreed-upon terms. Amounts related to future storage rental or prepaid service contracts for customers where storage rental fees or services are billed in advance are accounted for as deferred revenue and recognized ratably over the period the applicable storage rental or service is provided or performed. Revenues from the sales of products, which are included as a component of service revenues, are recognized when products are shipped and title has passed to the customer. Revenues from the sales of products, which represented less than 2% of consolidated revenue for the year ended December 31, 2017, have historically not been significant.

In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). ASU 2014-09 provides guidance for management to reassess revenue recognition as it relates to: (1) transfer of control, (2) variable consideration, (3) allocation of transaction price based on relative standalone selling price, (4) licenses, (5) time value of money, and (6) contract costs. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date ("ASU 2015-14"). ASU 2015-14 deferred the effective date of ASU 2014-09 for one year, making it effective for us on January 1, 2018, with early adoption permitted as of January 1, 2017. We will adopt ASU 2014-09 as of January 1, 2018. See Note 2.w. for additional information on ASU 2014-09.

Rent Normalization

We have entered into various leases for buildings that expire over various terms. Certain leases have fixed escalation clauses (excluding those tied to the consumer price index or other inflation-based indices) or other features (including return to original condition, primarily in the United Kingdom) which require normalization of the rental expense over the life of the lease, resulting in deferred rent being reflected as a liability in the accompanying Consolidated Balance Sheets. In addition, we have assumed various above and below market leases in connection with certain of our acquisitions. The difference between the present value of these lease obligations and the market rate at the date of the acquisition was recorded as either a deferred rent liability (which is a component of Other Long-Term Liabilities) or deferred rent asset (which is a component of Other within Other Assets, net) in our Consolidated Balance Sheets and is being amortized to rent expense.

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 ("ESPP") (together, "Employee Stock-Based Awards").

Our equity compensation plans generally provide that any unvested options and other awards granted thereunder shall vest immediately if an employee is terminated, or terminates their own employment for good reason (as defined in each plan), in connection with a vesting change in control (as defined in each plan). On January 20, 2015, our stockholders approved the adoption of the Iron Mountain Incorporated 2014 Stock and Cash Incentive Plan, as amended (the "2014 Plan").

The majority of our PUs are earned based on our performance against revenue and ROIC targets during their applicable performance period, therefore, we forecast the likelihood of achieving the predefined revenue and ROIC targets in order to calculate the expected PUs to be earned. We record a compensation charge based on either the forecasted PUs to be earned (during the performance period) or the actual PUs earned (at the three-year anniversary date of the grant date) over the vesting period for each of the awards. The fair value of PUs based on our performance against revenue and ROIC targets is the excess of the market price of our common stock at the date of grant over the purchase price (which is typically zero). For PUs earned based on a market condition, we utilize a Monte Carlo simulation to fair value these awards at the date of grant, and such fair value is expensed over the three-year performance period.

Performance Units

Under our various equity compensation plans, we may also make awards of PUs. For the majority of outstanding PUs, the number of PUs earned is determined based on our performance against predefined targets of revenue and return on invested capital ("ROIC"). The number of PUs earned may range from 0% to 200% of the initial award. The number of PUs earned is determined based on our actual performance as compared to the targets at the end of a three-year performance period. Certain PUs that we grant will be earned based on a market condition associated with the total return on our common stock in relation to a subset of the Standard & Poor's 500 Index rather than the revenue and ROIC targets noted above. The number of PUs earned based on this market condition may range from 0% to 200% of the initial award.

All of our PUs will be settled in shares of our common stock and are subject to cliff vesting three years from the date of the original PU grant. PUs awarded to employees who terminate their employment during the three-year performance period and on or after attaining age 55 and completing 10 years of qualifying service are eligible for pro-rated vesting, subject to the actual achievement against the predefined targets or a market condition as discussed above, based on the number of full years of service completed following the grant date (but delivery of the shares remains deferred). As a result, PUs are generally expensed over the three-year performance period.

All PUs accrue dividend equivalents associated with the underlying stock as we declare dividends. Dividends will generally be paid to holders of PUs in cash upon the settlement date of the associated PU and will be forfeited if the PU does not vest.

We offer an ESPP in which participation is available to substantially all United States and Canadian employees who meet certain service eligibility requirements. The ESPP provides a way for our eligible employees to become stockholders on favorable terms. The ESPP provides for the purchase of our common stock by eligible employees through successive offering periods. We have historically had two six-month offering periods per year, the first of which generally runs from June 1 through November 30 and the second of which generally runs from December 1 through May 31. During each offering period, participating employees accumulate after-tax payroll contributions, up to a maximum of 15% of their compensation, to pay the purchase price at the end of the offering. Participating employees may withdraw from an offering before the purchase date and obtain a refund of the amounts withheld as payroll deductions. At the end of the offering period, outstanding options under the ESPP are exercised, and each employee's accumulated contributions are used to purchase our common stock. The price for shares purchased under the ESPP is 95% of the fair market price at the end of the offering period, without a look-back feature. As a result, we do not recognize compensation expense for the ESPP shares purchased.

Expected volatility is calculated utilizing daily historical volatility over a period that equates to the expected life of the option. The risk-free interest rate was based on the United States Treasury interest rates whose term is consistent with the expected life (estimated period of time outstanding) of the stock options. Expected dividend yield is considered in the option pricing model and represents our current annualized expected per share dividends over the current trade price of our common stock. The expected life of the stock options granted is estimated using the historical exercise behavior of employees.

Under our various equity compensation plans, we may also grant RSUs. Our RSUs generally have a vesting period of three years from the date of grant. However, RSUs granted to our non-employee directors in 2015 and thereafter vest immediately upon grant.

All RSUs accrue dividend equivalents associated with the underlying stock as we declare dividends. Dividends will generally be paid to holders of RSUs in cash upon the vesting date of the associated RSU and will be forfeited if the RSU does not vest. The fair value of RSUs is the excess of the market price of our common stock at the date of grant over the purchase price (which is typically zero).

Stock Options

Under our various stock option plans, options are generally granted with exercise prices equal to the market price of the stock on the date of grant; however, in certain instances, options are granted at prices greater than the market price of the stock on the date of grant. The options we issue become exercisable ratably over a period of either (i) three years from the date of grant and have a contractual life of ten years from the date of grant, unless the holder's employment is terminated sooner, (ii) five years from the date of grant and have a contractual life of ten years from the date of grant, unless the holder's employment is terminated sooner, or (iii) ten years from the date of grant and have a contractual life of 12 years from the date of grant, unless the holder's employment is terminated sooner. Our non-employee directors are considered employees for purposes of our stock option plans and stock option reporting.

Income Taxes

Accounting for income taxes requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the tax and financial reporting bases of assets and liabilities and for loss and credit carryforwards. Valuation allowances are provided when recovery of deferred tax assets does not meet the more likely than not standard as defined in GAAP. We have elected to recognize interest and penalties associated with uncertain tax positions as a component of the (benefit) provision for income taxes in the accompanying Consolidated Statements of Operations.

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.

Allowance for Doubtful Accounts and Credit Memo Reserves

We maintain an allowance for doubtful accounts and credit memos 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 consider 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 may be required. We charge-off uncollectible balances as circumstances warrant, generally, no later than one year past due.

Fair Value Measurements

Entities are permitted under GAAP to elect to measure many financial instruments and certain other items at either fair value or cost. We have elected the cost measurement option.

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. A financial asset or liability's classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement.

The three levels of the fair value hierarchy are as follows:

Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access at the measurement date.

Level 2—Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs).

Level 3—Unobservable inputs that reflect our assumptions about the assumptions that market participants would use in pricing the asset or liability.

New Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ("ASU 2017-04"). ASU 2017-04 modifies the process by which entities will test goodwill for impairment. Under existing GAAP, when the carrying value of a reporting unit exceeds the reporting unit’s fair value, an entity would then proceed to a “Step 2” goodwill impairment analysis, which requires calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities, as if that reporting unit had been acquired in a business combination. Under ASU 2017-04, a goodwill impairment will be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying value of the reporting unit’s goodwill. We adopted ASU 2017-04 in the first quarter of 2017.

In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business ("ASU 2017-01"). ASU 2017-01 provides greater clarity on the definition of a business to assist entities in evaluating whether transactions should be accounted for as an acquisition or disposal of assets or businesses. We adopted ASU 2017-01 in the third quarter of 2017. ASU 2017-01 did not have a material impact on our consolidated financial statements.

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a Consensus of the FASB Emerging Issues Task Force) ("ASU 2016-18"). ASU 2016-18 requires that restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the cash and cash equivalents as of the beginning of the period to the cash and cash equivalents as of the end of the period in the statement of cash flows. We adopted ASU 2016-18 during the fourth quarter of 2017 retrospectively for the earliest year presented in our consolidated statement of cash flows. ASU 2016-18 did not have a material impact on our consolidated financial statements.

As Yet Adopted Accounting Pronouncements

a. ASU 2014-09

In May 2014, the FASB issued ASU No. 2014-09. ASU 2014-09 provides guidance for revenue recognition as it relates to: (1) transfer of control, (2) variable consideration, (3) allocation of transaction price based on relative standalone selling price, (4) licenses, (5) time value of money, and (6) contract costs.

ASU 2014-09 will replace the current revenue recognition criteria under GAAP, including industry-specific requirements, and provide companies with a single revenue recognition model for recognizing revenue from contracts with customers. The core principle of ASU 2014-09 is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for such goods or services. The two permitted transition methods under ASU 2014-09 are: (i) the full retrospective method, whereby ASU 2014-09 would be applied to each prior reporting period presented and the cumulative effect of adoption would be recognized at the earliest period shown, or (ii) the modified retrospective method, whereby the cumulative effect of applying ASU 2014-09 would be recognized at the date of initial application. In August 2015, the FASB issued ASU No. 2015-14, which deferred the effective date of ASU 2014-09 for one year, making ASU 2014-09 effective for us on January 1, 2018, with early adoption permitted as of January 1, 2017. We will adopt ASU 2014-09 as of January 1, 2018 using the modified retrospective method.

i. Accounting for Commissions

Under current GAAP, commissions that we pay related to our long-term storage contracts are expensed as incurred. Under ASU 2014-09, however, certain commissions will be capitalized and amortized over the period of expected earned revenue. In the year of adoption, this will result in increased contract assets on our Consolidated Balance Sheet, a reduction in selling, general and administrative expenses and a corresponding increase in amortization expense (assuming consistent levels of spending up through the adoption date) on our Consolidated Statement of Operations and an increase in cash flows from operating activities and a corresponding increase in cash used for investing activities on our Consolidated Statement of Cash Flows.

b. Other As Yet Adopted Accounting Pronouncements

In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"). ASU 2016-01 requires that most equity investments be measured at fair value, with subsequent changes in fair value recognized in net income, while eliminating the available-for-sale classification for equity securities with readily determinable fair values and the cost method for equity investments without readily determinable fair values. ASU 2016-01 also impacts financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. ASU 2016-01 is effective for us on January 1, 2018. We will adopt ASU 2016-01 on January 1, 2018 and are currently evaluating the impact ASU 2016-01 will have on our consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"). ASU 2016-02 requires lessees to recognize assets and liabilities on the balance sheet for the rights and obligations created by all leases with terms of more than 12 months. ASU 2016-02 also will require certain qualitative and quantitative disclosures designed to give financial statement users information on the amount, timing, and uncertainty of cash flows arising from leases. ASU 2016-02 will be effective for us on January 1, 2019, with early adoption permitted. We will adopt ASU 2016-02 on January 1, 2019 and are currently evaluating the impact ASU 2016-02 will have on our consolidated financial statements.

In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"). ASU 2017-12 amends the hedge accounting recognition and presentation requirements as outlined in Accounting Standards Codification Topic 815 with the objective of improving the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements and enhance the transparency and understandability of hedge transactions. In addition, ASU 2017-12 simplifies the application of the hedge accounting guidance. ASU 2017-12 is effective for us on January 1, 2019, with early adoption permitted. We are currently evaluating the impact ASU 2017-12 will have on our consolidated financial statements.

ii. Accounting for Initial Moves

Under current GAAP, intake costs incurred but not charged to a customer to transport records to our facilities, which include labor and transportation costs, are capitalized and amortized as a component of depreciation and amortization in our Consolidated Statements of Operations. Under ASU 2014-09, however, the revenue and costs associated with all initial moves of physical storage, regardless of whether or not the services associated with such initial moves are provided to the customer at no charge, will be deferred and recognized over the period consistent with the transfer of the service to the customer to which the asset relates. In the year of adoption, this will result in decreased assets and increased deferred revenue on our Consolidated Balance Sheet, a reduction in cost of sales and a corresponding increase in amortization expense (assuming consistent levels of initial move spending through the adoption date) on our Consolidated Statement of Operations and an increase in cash flows from operating activities and a corresponding increase in cash used for investing activities on our Consolidated Statement of Cash Flows.

Redeemable Noncontrolling Interests

Certain unaffiliated third parties own noncontrolling interests in our consolidated subsidiaries in Chile, India and South Africa. The underlying shareholder agreements between us and our noncontrolling interest shareholders for these subsidiaries contain provisions under which the noncontrolling interest shareholders can require us to purchase their respective interests in such subsidiaries at certain times and at a purchase price as stipulated in the underlying shareholder agreements (generally at fair value). These put options make these noncontrolling interests redeemable and, therefore, these noncontrolling interests are classified as temporary equity outside of stockholders' equity. Redeemable noncontrolling interests are reported at the higher of their redemption value or the noncontrolling interest holders' proportionate share of the underlying subsidiaries net carrying value. Increases or decreases in the redemption value of the noncontrolling interest are offset against Additional Paid-in Capital.

Long-Lived Assets

We review long-lived assets, including all finite-lived intangible assets, for impairment whenever events or changes in circumstances indicate the carrying amount of such assets may not be recoverable. Recoverability of these assets is determined by comparing the forecasted undiscounted net cash flows of the operation to which the assets relate to their carrying amount. The operations are generally distinguished by the business segment and geographic region in which they operate. If it is determined that we are unable to recover the carrying amount of the assets, the long-lived assets are written down, on a pro rata basis, to fair value. Fair value is determined based on discounted cash flows or appraised values, depending upon the nature of the assets. Long-lived assets, including finite-lived intangible assets, are amortized over their useful lives. Annually, or more frequently if events or circumstances warrant, we assess whether a change in the lives over which long-lived assets, including finite-lived intangible assets, are amortized is necessary.