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Summary of significant accounting policies | 6 Months Ended
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Jun. 30, 2019
Summary of significant accounting policies |
Summary of significant accounting policies | 2. Summary of significant accounting policies ​ Basis of presentation ​ The accompanying interim condensed consolidated financial statements and related notes for the three and six months ended June 30, 2019 and 2018 are unaudited. The unaudited interim condensed consolidated financial information has been prepared in accordance with the rules and regulations of the SEC for interim financial information. Accordingly, they do not include all information and footnotes required by generally accepted accounting principles (“GAAP”) in the United States of America (“U.S.”) for complete financial statements. These financial statements should be read in conjunction with the audited consolidated financial statements and the accompanying notes for the year ended December 31, 2018 contained in our annual report on Form 10-K filed with the SEC on March 1, 2019. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and in the opinion of management, reflect all adjustments, consisting of normal recurring adjustments, necessary for a fair statement of our results of operations for the three and six months ended June 30, 2019 and 2018, our cash flows for the six months ended June 30, 2019 and 2018, and our financial position as of June 30, 2019. The year-end balance sheet data was derived from audited consolidated financial statements but does not include all disclosures required by GAAP. Interim results are not necessarily indicative of the results to be expected for an entire year or any other future year or interim period. ​ In June 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, which eliminates the separate accounting model for nonemployee share-based payment awards and generally requires companies to account for share-based payment transactions with nonemployees in the same way as share-based payment transactions with employees. The accounting remains different for attribution, which represents how the equity-based payment cost is recognized over the vesting period, and a contractual term election for valuing nonemployee equity share options. The standard is effective for interim and annual periods beginning after December 15, 2018. We adopted ASU 2018-07 on January 1, 2019 and the adoption of this standard did not have a material impact on our condensed consolidated financial statements. ​ In February 2016, the FASB issued a new standard related to leases, which was codified into Accounting Standards Codification (“ASC”) 842, Leases. ASC 842 requires lessees to recognize assets and liabilities for all leases with lease terms of more than 12 months on the balance sheet. Under ASC 842, the recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee will depend on its classification as a finance or operating lease. On January 1, 2019, we adopted ASC 842 using the modified retrospective transition approach. ASC 842 permits two methods of adoption and we elected to apply the guidance to each lease that had commenced as of January 1, 2019 with a cumulative-effect adjustment to the opening balance of retained earnings as of that date. ASC 842 permits various optional transition practical expedients. The discount rate used to calculate the present value of the future payments was determined as of January 1, 2019 for existing lease contracts and was generally based on our incremental borrowing rate as of January 1, 2019 commensurate with the remaining lease term. We also elected the package of practical expedients which included the following: (i) an entity need not reassess whether any expired or existing contracts are or contain leases; (ii) an entity need not reassess the lease classification for any expired or existing leases; and (iii) an entity need not reassess initial direct costs for any existing leases. The standard had a material impact on our condensed consolidated balance sheet but did not have an impact on our condensed consolidated statement of operations and our condensed consolidated statement of cash flows. The most significant impact was the recognition of right-of-use (“ROU”) assets and liabilities related to our operating leases, while our accounting for finance leases remained substantially unchanged. Adoption of the new standard resulted in the recording of $16,916 of operating lease ROU assets and $22,338 of operating lease ROU liabilities as of January 1, 2019. ​ Principles of consolidation ​ The unaudited condensed consolidated financial statements include our accounts and the accounts of our majority owned subsidiaries. We consolidate our 70% ownership of Chicago Concourse Development Group, LLC and our 75% ownership of Boingo Holding Participacoes Ltda. in accordance with ASC 810, Consolidation. Other parties’ interests in consolidated entities are reported as non-controlling interests. All intercompany balances and transactions have been eliminated in consolidation. ​ Marketable securities ​ Our marketable securities consist of available-for-sale securities with original maturities exceeding three months. According to ASC 320, Investments—Debt and Equity Securities, we have classified securities, which have readily determinable fair values and are highly liquid, as short-term because such securities are expected to be realized within a one-year period. At June 30, 2019, we had $42,799 in marketable securities. We had no marketable securities at December 31, 2018. ​ Marketable securities are reported at fair value with the related unrealized gains and losses reported as other comprehensive income (loss) until realized or until a determination is made that an other-than-temporary decline in market value has occurred. No significant unrealized gains and losses have been reported during the periods presented. Factors considered by us in assessing whether an other-than-temporary impairment has occurred include the nature of the investment, whether the decline in fair value is attributable to specific adverse conditions affecting the investment, the financial condition of the investee, the severity and the duration of the impairment and whether we have the ability to hold the investment to maturity. When it is determined that an other-than-temporary impairment has occurred, the investment is written down to its market value at the end of the period in which it is determined that an other-than-temporary decline has occurred. The cost of marketable securities sold is based upon the specific identification method. Any realized gains or losses on the sale of investments are reflected as a component of interest and other expense, net. ​ For the three and six months ended June 30, 2019, we had no significant realized or unrealized gains or losses from investments in marketable securities classified as available-for-sale. As of June 30, 2019, we had $45 of cumulative unrealized gains, net of tax, which was $0 as of June 30, 2019 due to the full valuation allowance established against our deferred tax assets, in accumulated other comprehensive loss. ​ Segment and geographic information ​ We operate as one reportable segment; a service provider of wireless connectivity solutions across our managed and operated network and aggregated network for mobile devices such as laptops, smartphones, tablets and other wireless-enabled consumer devices. This single segment is consistent with the internal organization structure and the manner in which operations are reviewed and managed by our Chief Executive Officer, the chief operating decision maker. ​ All significant long-lived tangible assets are held in the United States of America. We do not disclose sales by geographic area because to do so would be impracticable. ​ The following is a summary of our revenue disaggregated by product offerings:
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Three Months Ended | ​ | Six Months Ended
​ | ​ | June 30, | ​ | June 30,
​ |  | 2019 |  | 2018 |  | 2019 |  | 2018
Revenue: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
DAS | ​ | $ | 27,622 | ​ | $ | 21,885 | ​ | $ | 51,717 | ​ | $ | 45,530
Military/multifamily | ​ | ​ | 24,396 | ​ | ​ | 16,735 | ​ | ​ | 50,293 | ​ | ​ | 32,589
Wholesale—Wi-Fi | ​ |  | 10,718 | ​ |  | 13,530 | ​ | ​ | 21,738 | ​ | ​ | 24,679
Retail | ​ | ​ | 3,847 | ​ | ​ | 4,566 | ​ | ​ | 7,773 | ​ | ​ | 9,876
Advertising and other | ​ |  | 1,971 | ​ |  | 2,885 | ​ | ​ | 3,506 | ​ | ​ | 5,086
Total revenue | ​ | $ | 68,554 | ​ | $ | 59,601 | ​ | $ | 135,027 | ​ | $ | 117,760
​ Revenue recognition ​ We generate revenue from several sources including: (i) DAS customers that are telecom operators under long-term contracts for access to our DAS at our managed and operated locations, (ii) military and retail customers under subscription plans for month-to-month network access that automatically renew, and military and retail single-use access from sales of hourly, daily or other single-use access plans, (iii) arrangements with property owners for multifamily properties that provide for network installation and monthly Wi-Fi services and support for residents and employees, (iv) arrangements with wholesale Wi-Fi customers that provide software licensing, network access, and/or professional services fees, and (v) display advertisements and sponsorships on our walled garden sign-in pages. Software licensed by our wholesale platform services customers can only be used during the term of the service arrangements and has no utility to them upon termination of the service arrangement. ​ Revenues are recognized when a contract with a customer exists and control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services and the identified performance obligation has been satisfied. Contracts entered into at or near the same time with the same customer are combined and accounted for as a single contract if the contracts have a single commercial objective, the amount of consideration is dependent on the price or performance of the other contract, or the services promised in the contracts are a single performance obligation. Contract amendments are routine in the performance of our DAS, wholesale Wi-Fi, and advertising contracts. Contracts are often amended to account for changes in contract specifications or requirements or expand network access services. In most instances, our DAS and wholesale Wi-Fi contract amendments are for additional goods or services that are distinct, and the contract price increases by an amount that reflects the standalone selling price of the additional goods or services; therefore, such contract amendments are accounted for as separate contracts. Contract amendments for our advertising contracts are also generally for additional goods or services that are distinct; however, the contract price does not increase by an amount that reflects the standalone selling price of the additional goods or services. Advertising contract amendments are therefore generally accounted for as contract modifications under the prospective method. Contract amendments to transaction prices with no change in remaining services are accounted for as contract modifications under the cumulative catch-up method. ​ A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account in ASC 606, Revenue from Contracts with Customers. A contract’s transaction price is allocated to each distinct performance obligation and is recognized as revenue when, or as, the performance obligation is satisfied, which typically occurs when the services are rendered. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment. Our contracts with customers may include multiple performance obligations. For such arrangements, we allocate revenue to each performance obligation based on its relative standalone selling price. We generally determine standalone selling prices based on the prices charged to customers. Judgment may be used to determine the standalone selling prices for items that are not sold separately, including services provided at no additional charge. Most of our performance obligations are satisfied over time as services are provided. We generally recognize revenue on a gross basis as we are primarily responsible for fulfilling the promises to provide the specified goods or services, we are responsible for paying all costs related to the goods or services before they have been transferred to the customer, and we have discretion in establishing prices for the specified goods or services. Revenue is presented net of any sales and value added taxes. ​ Payment terms vary on a contract-by-contract basis, although terms generally require payment within 30 to 60 days for non-recurring payments, the first day of the monthly or quarterly billing cycle for recurring payments for DAS and wholesale Wi-Fi contracts, and the first day of the month prior to the month that services are provided for multifamily contracts. We apply a practical expedient for purposes of determining whether a significant financing component may exist for our contracts if, at contract inception, we expect that the period between when we transfer the promised good or service to the customer and when the customer pays for that good or service will be one year or less. In instances where the customer pays for a good or service one year or more in advance of the period when we transfer the promised good or service to the customer, we have determined our contracts generally do not include a significant financing component. The primary purpose of our invoicing terms is not to receive financing from our customers or to provide customers with financing but rather to maximize our profitability on the customer contract. Specifically, inclusion of non-refundable upfront fees in our long-term customer contracts increases the likelihood that the customer will be committed through the end of the contractual term and ensures recoverability of the capital outlay that we incur in expectation of the customer fulfilling its contractual obligations. We may also provide service credits to our customers if we fail to meet contractual monthly system uptime requirements and we account for the variable consideration related to these service credits using the most likely amount method. ​ For contracts that include variable consideration, we estimate the amount of consideration at contract inception under the expected value method or the most likely amount method and include the amount of variable consideration that is not considered to be constrained. Significant judgment is used in constraining estimates of variable consideration. We update our estimates at the end of each reporting period as additional information becomes available. ​ Timing of revenue recognition may differ from the timing of invoicing to customers. We record unbilled receivables (contract assets) when revenue is recognized prior to invoicing, deferred revenue (contract liabilities) when revenue is recognized after invoicing, and receivables when we have an unconditional right to consideration to invoice and receive payment in the future. We present our DAS, multifamily, and wholesale Wi-Fi contracts in our condensed consolidated balance sheet as either a contract asset or a contract liability with any unconditional rights to consideration presented separately as a receivable. Our other customer contracts generally do not have any significant contract asset or contract liability balances. Generally, a significant portion of the billing for our DAS contracts occurs prior to revenue recognition, resulting in our DAS contracts being presented as contract liabilities. In contrast, our wholesale Wi-Fi contracts that contain recurring fees with annual escalations are generally presented as contract assets as revenue is recognized prior to invoicing. Our multifamily contracts can be presented as either contract liabilities or contract assets primarily as a result of timing of invoicing for the network installations. ​ We recognize an asset for the incremental costs of obtaining a contract with a customer if we expect the benefit of those costs to be longer than one year. We have determined that certain sales incentive programs meet the requirements to be capitalized. Total capitalized costs to obtain a contract were immaterial during the three and six months ended June 30, 2019 and are included in prepaid expenses and other current assets and non-current other assets on our condensed consolidated balance sheets. We apply a practical expedient to expense costs as incurred for costs to obtain a contract with a customer when the amortization period would have been one year or less, the most significant of which relates to sales commissions related to obtaining our advertising customer contracts. Contract costs are evaluated for impairment in accordance with ASC 310, Receivables. ​ DAS ​ We enter into long-term contracts with telecom operators at our managed and operated locations. The initial term of our contracts with telecom operators generally range from five to twenty years and the agreements generally contain renewal options. Some of our contracts provide termination for convenience clauses that may or may not include substantive termination penalties. We apply judgment in determining the contract term, the period during which we have present and enforceable rights and obligations. Our DAS customer contracts generally contain a single performance obligation—provide non-exclusive access to our DAS or small cell networks to provide telecom operators’ customers with access to the licensed wireless spectrum, together with providing telecom operators with construction, installation, optimization/engineering, maintenance services and agreed-upon storage space for the telecom operators’ transmission equipment, each related to providing such licensed wireless spectrum to the telecom operators. The performance obligation is considered a series of distinct services as the performance obligation is satisfied over time and the same time-based input method would be used to measure our progress toward complete satisfaction of the performance obligation to transfer each distinct service in the series to the customer. Our contract fee structure generally includes a non-refundable upfront fee and we evaluated whether customer options to renew services give rise to a material right that should be accounted for as a separate performance obligation because of those non-refundable upfront fees. We believe that a material right generally does not exist for our DAS customer contracts that contain renewal options because the telecom operators’ decision to renew is highly dependent upon our ability to maintain our exclusivity as the DAS service provider at the venue location and our limited operating history with venue and customer renewals. The telecom operators will make the decision to incur the capital improvement costs at the venue location irrespective of our remaining exclusivity period with the venue as the telecom operators expect that the assets will continue to be serviced regardless of whether we will remain such exclusive DAS service provider. Our contracts also provide our DAS customers with the option to purchase additional future services such as upgrades or enhancements. This option is not considered to provide the customer with a material right that should be accounted for as a separate performance obligation since the cost of the additional future services depends entirely on the market rate of such services at the time such services are requested and we are not automatically obligated to stand ready to deliver these additional goods or services as the customer may reject our proposal. Periodically, we install and sell DAS networks to customers where we do not have service contracts or remaining obligations beyond the installation of those networks and we recognize build-out fees for such projects as revenue when the installation work is completed, and the network has been accepted by the customer. ​ Our contract fee structure may include varying components of an upfront build-out fee and recurring access, maintenance, and other fees. The upfront build-out fee is generally structured as a firm-fixed price or cost-plus arrangement and becomes payable as certain contract and/or construction milestones are achieved. Our DAS and small cell networks are neutral-host networks that can accommodate multiple telecom operators. Some of our DAS customer contracts provide for credits that may be issued to existing telecom operators for additional telecom operators subsequently joining the DAS network. The credits are generally based upon a fixed dollar amount per additional telecom operator, a fixed percentage amount of the original build-out fee paid by the telecom operator per additional telecom operator, or a proportionate share based upon the split among the relevant number of telecom operators for the actual costs incurred by all telecom operators to construct the DAS network. In most cases, there is significant uncertainty on whether additional telecom operator contracts will be executed at inception of the contract with the existing telecom operator. We believe that the upfront build-out fee is fixed consideration once the build-out is complete and any subsequent credits that may be issued would be accounted for in a manner similar to a contract modification under the prospective method because (i) the execution of customer contracts with additional telecom carriers is at our sole election and (ii) we would not execute agreements with additional telecom carriers if it would not increase our revenues and gross profits at the venue level. Further, the credits issued to the existing telecom operator changes the transaction price on a go-forward basis, which corresponds with the decline in service levels for the existing telecom operator once the neutral-host DAS network can be accessed by the additional telecom operator. The recurring access, maintenance, and other fees generally escalate on an annual basis. The recurring fees are variable consideration until the contract term and annual escalation dates are fixed. We estimate the variable consideration for our recurring fees using the most likely amount method based on the expected commencement date for the services. We evaluate our estimates of variable consideration each period and record a cumulative catch-up adjustment in the period in which changes occur for the amount allocated to satisfied performance obligations. ​ We generally recognize revenue related to our single performance obligation for our DAS customer contract monthly over the contract term once the customer may access the DAS network and we commence maintenance on the DAS network. ​ Military and retail ​ Military and retail customers must review and agree to abide by our standard “Customer Agreement (With Acceptable Use Policy) and End User License Agreement” before they are able to sign up for our subscription or single-use Wi-Fi network access services. Our military and retail customer contracts generally contain a single performance obligation—provide non-exclusive access to Wi-Fi services, together with performance of standard maintenance, customer support, and the Wi-Finder app to facilitate seamless connection to the Company’s Wi-Fi network. The performance obligation is considered a series of distinct services as the performance obligation is satisfied over time and the same time-based input method would be used to measure our progress toward complete satisfaction of the performance obligation to transfer each distinct service in the series to the customer. Our contracts also provide our military and retail subscription customers with the option to renew the agreement when the subscription term is over. We do not consider this option to provide the customer with a material right that should be accounted for as a separate performance obligation because the customer would not receive a discount if it decided to renew and the option to renew is cancellable with 5 days’ notice prior to the end of the then current term by either party. ​ The contract transaction price is determined based on the subscription or single-use plan selected by the customer. Our military and retail service plans are for fixed price services as described on our website. From time to time, we offer promotional discounts that result in an immediate reduction in the price paid by the customer. Subscription fees from military and retail customers are paid monthly in advance. We provide refunds for our military and retail services on a case-by-case basis. Refunds and credit card chargeback amounts are not significant and are recorded as contra-revenue in the period the refunds are made, or chargebacks are received. ​ Subscription fee revenue is recognized ratably over the subscription period. Revenue generated from military and retail single-use access is recognized when access is provided, and the performance obligation is satisfied. ​ Multifamily ​ We enter into long-term contracts with property owners. The initial term of our contracts with property owners generally range from three to five years and the contracts may contain renewal options. Some of our contracts provide termination for convenience clauses that may or may not include substantive termination penalties. We apply judgment in determining the contract term, which is the period during which we have present and enforceable rights and obligations. Our customer contracts generally contain two performance obligations: (i) install the network required to provide Wi-Fi services; and (ii) provide Wi-Fi services and technical support to the residents and employees. Our contracts may also provide our property owners with the option to renew the agreement. We do not consider this option to provide the property owner with a material right that should be accounted for as a separate performance obligation because the property owner would not receive a discount if it decided to renew and the option to renew is generally cancellable by either party subject to the notice of non-renewal requirements specified in the contract. Our contracts may also provide our customers with the option to purchase additional future services. We do not consider this option to provide the customer with a material right that should be accounted for as a separate performance obligation since the cost of the additional future services are generally at market rates for such services and we are not automatically obligated to stand ready to deliver these additional goods or services because the customer may reject our proposal. ​ Our contract fee structure includes a network installation fee and recurring Wi-Fi service and support fees. The network installation fee is generally structured as a firm-fixed price arrangement and becomes payable as certain contract and/or installation milestones are achieved. We generally estimate variable consideration for unpriced change orders using the most likely amount method based on the expected price for those services. If network installations are not completed by specified dates, we may be subject to network installation penalties. We estimate the variable consideration for our network installation fees using the most likely amount method based on the amount of network installation penalties we expect to incur. Title to the network generally transfers to the property owner once installation is completed and the network has been accepted. We generally recognize revenue related to our network installation performance obligation using a cost-to-cost method over the network installation period. We may provide latent defect warranties for materials and installation labor services related to our network installation services. Our warranty obligations are generally not accounted for as separate performance obligations as warranties cannot be separately purchased and warranties do not provide a service in addition to the assurance that the network will function as expected. ​ The recurring fees commence once the network is launched with recurring fees generally based upon a fixed or variable occupancy rate. The recurring Wi-Fi service fees may be adjusted prospectively for changes in circuit and/or video content costs, and Wi-Fi support fees may escalate on an annual basis. We estimate the variable consideration for our recurring fees using the expected value method with the exception of the variable consideration related to actual occupancy rates, which we record when we have the contractual right to bill. We evaluate our estimates of variable consideration each period and record a cumulative catch-up adjustment in the period in which changes occur for the amount allocated to satisfied performance obligations. We recognize revenue related to the recurring fees on a monthly basis over the contract term as the Wi-Fi services and support is rendered, and the performance obligation is satisfied. ​ Wholesale Wi-Fi ​ We enter into long-term contracts with enterprise customers such as telecom operators, cable companies, technology companies, and enterprise software/services companies, that pay us usage-based Wi-Fi network access and software licensing fees to allow their customers' access to our footprint worldwide. We also enter into long-term contracts with financial institutions and other enterprise customers who provide access to our Wi-Fi footprint as a value-added service for their customers. The initial term of our contracts with wholesale Wi-Fi customers generally range from one to three years and the agreements generally contain renewal options. Some of our contracts provide termination for convenience clauses that may or may not include substantive termination penalties. We apply judgment in determining the contract term, the period during which we have present and enforceable rights and obligations. Our wholesale Wi-Fi customer contracts generally contain a single performance obligation-provide non-exclusive rights to access our Wi-Fi networks to provide wholesale Wi-Fi customers' end customers with access to the high-speed broadband network that may be bundled together with integration services, support services, and/or performance of standard maintenance. The performance obligation is considered a series of distinct services as the performance obligation is satisfied over time and the same time-based input method or usage-based output method would be used to measure our progress toward complete satisfaction of the performance obligation to transfer each distinct service in the series to the customer. Our contracts may also provide our enterprise customers with the option to renew the agreement. This option is not considered to provide the customer with a material right that should be accounted for as a separate performance obligation because the customer would not receive a discount if it decided to renew and the option to renew is generally cancellable by either party subject to the notice of non-renewal requirements specified in the contract. Our contracts may also provide our wholesale Wi-Fi customers with the option to purchase additional future services. We do not consider this option to provide the customer with a material right that should be accounted for as a separate performance obligation since the cost of the additional future services are generally at market rates for such services and we are not automatically obligated to stand ready to deliver these additional goods or services because the customer may reject our proposal. Periodically, we install and sell Wi-Fi networks to customers where we do not have service contracts or remaining obligations beyond the installation of those networks and we recognize build-out fees for such projects as revenue when the installation work is completed, and the network has been accepted by the customer. ​ Our contract fee structure may include varying components of a minimum fee and usage-based fees. Minimum fees represent fixed price consideration while usage-based fees represent variable consideration. With respect to variable consideration, our commitment to our wholesale Wi-Fi customers consists of providing continuous access to the network. It is therefore a single performance obligation to stand ready to perform and we allocate the variable fees charged for usage when we have the contractual right to bill. The variable component of revenue is recognized based on the actual usage during the period. ​ Wholesale Wi-Fi revenue is recognized as it is earned over the relevant contract term with variable consideration recognized when we have the contractual right to bill. ​ Advertising ​ We generally enter into short-term cancellable insertion orders with our advertising customers for advertising campaigns that are served at our managed and operated locations and other locations where we solely provide authorized access to a partner’s Wi-Fi network through sponsored and promotional programs. Our sponsorship advertising arrangements are generally priced under a cost per engagement structure, which is a set price per click or engagement, or a cost per install structure for third party application downloads. Our display advertising arrangements are priced based on cost per thousand impressions. Insertion orders may also include bonus items. Our advertising customer contracts may contain multiple performance obligations with each distinct service. These distinct services may include an advertisement video or banner impressions in the contract bundled with the requirement to provide network, space on the website, and integration of customer advertisement onto the website, and each is generally considered to be its own performance obligation. The performance obligations are considered a series of distinct services as the performance obligations are satisfied over time and the same action-based output method would be used to measure our progress toward complete satisfaction of the performance obligation to transfer each distinct service in the series to the customer. ​ The contract transaction price is comprised of variable consideration based on the stated rates applied against the number of units delivered inclusive of the bonus units subject to the maximums provided for in the insertion order. It is customary for us to provide additional units over and above the amounts contractually required; however, there are a number of factors that can also negatively impact our ability to deliver the units required by the customer such as service outages at the venue resulting from power or circuit failures and customer cancellation of the remaining undelivered units under the insertion order due to campaign performance or budgetary constraints. Typically, the advertising campaign periods are short in duration. We therefore use the contractual rates per the insertion orders and actual units delivered to determine the transaction price each period end. The transaction price is allocated to each performance obligation based on the standalone selling price of each performance obligation. ​ Advertising revenue is recognized ratably over the service period based on actual units delivered subject to the maximums provided for in the insertion order. ​ Leases ​ We determine if an arrangement is a lease at inception. Operating leases are included in operating lease right-of-use assets, current portion of operating and finance leases, and long-term portion of operating and finance leases in our condensed consolidated balance sheets. Finance leases are included in property and equipment, net, current portion of operating and finance leases, and long-term portion of operating and finance leases in our condensed consolidated balance sheets. ​ Operating and finance lease ROU assets and ROU liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of future payments. The ROU asset also includes any lease payments made and excludes lease incentives and initial direct costs incurred. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. We have lease agreements with lease and non-lease components, which are accounted for separately for the asset classes maintained. We exclude short-term leases with a lease term of 12 months or less at the commencement date from our condensed consolidated balance sheets. ​ Income taxes ​ We calculate our interim income tax provision in accordance with ASC 270, Interim Reporting, and ASC 740, Accounting for Income Taxes. At the end of each interim period, we estimate the annual effective tax rate and apply that rate to our ordinary quarterly earnings. The tax expense or benefit related to significant, unusual, or extraordinary items is recognized in the interim period in which those items occur. In addition, the effect of changes in enacted tax laws, rates, or tax status is recognized in the interim period in which the change occurs. Excess windfall tax benefits and tax deficiencies related to our stock option exercises and restricted stock unit (“RSU”) vesting are recognized as an income tax benefit or expense in our condensed consolidated statements of operations in the period they are deducted on the income tax return. Excess windfall tax benefits and tax deficiencies are therefore not anticipated when determining the annual effective tax rate and are instead recognized in the interim period in which those items occur. ​ The computation of the annual estimated effective tax rate at each interim period requires certain estimates and significant judgment, including the expected operating income (loss) for the year, projections of the proportion of income (loss) earned and taxed in various states, permanent and temporary differences as a result of differences between amounts measured and recognized in accordance with tax laws and financial accounting standards, and the likelihood of recovering deferred tax assets generated in the current year. The accounting estimates used to compute the provision for income taxes may change as new events occur, additional information is obtained, or as the tax environment changes. ​ As of June 30, 2019, we had an immaterial amount of unremitted earnings in our subsidiaries located outside of the U.S. for which state taxes have not been paid. Our intention is to indefinitely reinvest these earnings outside the U.S. If we were to remit our foreign earnings, we would be subject to state income taxes or withholding taxes imposed on actual distributions, or currency transaction gains (losses) that would result in taxation upon remittance. However, the amounts of any such tax liabilities resulting from the repatriation of foreign earnings are not material. ​ Foreign currency translation ​ Our Brazilian subsidiary uses the Brazilian Real as its functional currency. Assets and liabilities of our Brazilian subsidiary are translated to U.S. dollars at period-end rates of exchange, and revenues and expenses are translated at average exchange rates prevailing for each month. The resulting translation adjustments are made directly to a separate component of other comprehensive loss, which is reflected in stockholders’ equity in our condensed consolidated balance sheets. As of June 30, 2019 and December 31, 2018, the Company had $(1,257) and $(1,295), respectively, of cumulative foreign currency translation adjustments, net of tax, which was $0 as of June 30, 2019 and December 31, 2018 due to the full valuation allowance established against our deferred tax assets, in accumulated other comprehensive loss. ​ The functional currency for our other foreign subsidiaries is the U.S. dollar. Gains and losses from the revaluation of foreign currency transactions and monetary assets and liabilities are included in the condensed consolidated statements of operations. ​ Use of estimates ​ The preparation of accompanying condensed consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the dates of the accompanying condensed consolidated financial statements, and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. Assets and liabilities which are subject to significant judgment and the use of estimates include the allowance for doubtful accounts, recoverability of goodwill and long-lived assets, valuation allowances with respect to deferred tax assets, useful lives associated with property and equipment, valuation of ROU assets and ROU liabilities, valuation and useful lives of intangible assets, valuation of contingent consideration, contract assets and contract liabilities including estimates of variable consideration, and the valuation and assumptions underlying stock-based compensation and other equity instruments. On an ongoing basis, we evaluate our estimates compared to historical experience and trends, which form the basis for making judgments about the carrying value of assets and liabilities. ​ Fair value of financial instruments ​ Fair value is defined as the price that would be received from selling an asset, or paid to transfer a liability, in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, we consider the principal or most advantageous market in which it would transact, and we consider assumptions that market participants would use when pricing the asset or liability. ​ The accounting guidance for fair value measurement also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard establishes a fair value hierarchy based on the level of independent, objective evidence surrounding the inputs used to measure fair value. A financial instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The fair value hierarchy is as follows: ​
| ● | Level 1—Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.
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| ● | Level 2—Quoted prices for identical assets and liabilities in markets that are not active, quoted prices for similar assets and liabilities in active markets or financial instruments for which significant inputs are observable, either directly or indirectly.
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| ● | Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
​ The carrying amount reflected in the accompanying condensed consolidated balance sheets for cash and cash equivalents, accounts receivable, prepaid expenses and other current assets, other assets, accounts payable, accrued expenses and other liabilities, and deferred revenue approximates fair value due to the short duration and nature of these financial instruments. ​ Recent accounting pronouncements ​ In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which requires customers to apply the same criteria for capitalizing implementation costs incurred in a cloud computing arrangement that is hosted by the vendor as they would for an arrangement that has a software license. The standard is effective for interim and annual periods beginning after December 15, 2019 and early adoption is permitted. The standard can be adopted prospectively or retrospectively. We are currently evaluating the expected impact of this new standard.

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