2. Summary of significant accounting policies

Basis of presentation and consolidation

Our consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP").

The accompanying 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 Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("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.

Prior to August 4, 2015, we had a 70% ownership of Concourse Communications Detroit, LLC. On August 4, 2015, we purchased the remaining 30% ownership interest from the non-controlling interest owners for $1,150. We accounted for this transaction as an acquisition of the remaining interest of an entity that had already been majority-owned by the Company. The purchase resulted in a reduction to additional paid-in capital of $1,150 representing excess purchase price over the carrying amount of the non-controlling interests. Prior to this purchase, we had a controlling interest in this subsidiary, and therefore, this subsidiary had been and will continue to be consolidated with the Company's operations.

We early adopted FASB Accounting Standards Update, ("ASU") 2015-17, Balance Sheet Classification of Deferred Taxes, on a retrospective basis as of December 31, 2015. As a result of this adoption, the consolidated balance sheet as of December 31, 2014 has been revised to reflect reclassifications of $787 from current deferred tax assets to noncurrent deferred tax liabilities.

During the year ended December 31, 2013, the Company recorded certain out-of-period adjustments that decreased net loss attributable to common stockholders by $217. The impact of these out-of-period adjustments is not considered material, individually and in the aggregate, to any of the current or prior annual periods.

Use of estimates

The preparation of accompanying 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 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, uncertain tax positions, useful lives associated with property and equipment, valuation and useful lives of intangible assets, valuation of contingent 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.

Concentrations of credit risk

Financial instruments that potentially subject us to significant concentrations of credit risk consist primarily of cash and cash equivalents, marketable securities and accounts receivable. We maintain our cash and cash equivalents and marketable securities with institutions with high credit ratings. We extend credit based upon the evaluation of the customer's financial condition and generally collateral is not required. We maintain an allowance for doubtful accounts based upon expected collectability of accounts receivable. We primarily estimate our allowance for doubtful accounts based on a specific review of significant outstanding accounts receivable. For the years ended December 31, 2015 and 2014, one customer accounted for 17% and 15% of total revenue, respectively. For the year ended December 31, 2013, two customers each accounted for 14% of total revenue. At December 31, 2015, four customers accounted for 28%, 19%, 19% and 10% of the total accounts receivable, respectively. At December 31, 2014, two customers accounted for 30% and 17% of the total accounts receivable, respectively.

Cash and cash equivalents

Cash and cash equivalents include highly liquid investments that are readily convertible into known amounts of cash with original maturities of three months or less when acquired. At December 31, 2015 and 2014, cash equivalents consisted of money market funds.

Marketable securities

Our marketable securities consist of available-for-sale securities with original maturities exceeding three months. In accordance with FASB 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 December 31, 2015 and 2014, we had $0 and $1,614, respectively, in marketable securities.

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 years 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) income, net.

For the years ended December 31, 2015, 2014 and 2013, we had no significant realized or unrealized gains or losses from investments in marketable securities classified as available-for-sale. As of December 31, 2015 and 2014, we had no unrealized gains or losses in accumulated other comprehensive income (loss).

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.

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.

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 consolidated balance sheets for cash and cash equivalents, restricted cash, marketable securities, accounts receivable, prepaid expenses and other current assets, accounts payable, accrued expenses and other liabilities approximates fair value due to the short-term nature of these financial instruments.

Business combinations

The results of businesses acquired in a business combination are included in the Company's consolidated financial statements from the date of the acquisition. Purchase accounting results in assets and liabilities of an acquired business being recorded at their estimated fair values on the acquisition date. Any excess consideration over the fair value of assets acquired and liabilities assumed is recognized as goodwill.

The Company performs valuations of assets acquired and liabilities assumed from a business acquisition and will allocate the purchase price to its respective net tangible and intangible assets. Determining the fair value of assets acquired and liabilities assumed requires management to use significant judgment and estimates including the selection of valuation methodologies, estimates of future revenues and cash flows, discount rates, royalty rates and selection of comparable companies. The Company engages the assistance of valuation specialists in concluding on fair value measurements in connection with fair values of assets and liabilities assumed in a business combination.

Transaction costs associated with business combinations are expensed as incurred, and are included in general and administrative expenses in the consolidated statements of operations. There were no transaction costs for the years ended December 31, 2015 and 2014. Transaction cost for the year ended December 31, 2013 was $354.

Property and equipment

Property and equipment are generally stated at historical cost, less accumulated depreciation and amortization. The Company's cost basis includes property and equipment acquired in business combinations that were initially recorded at fair value as of the date of acquisition. Maintenance and repairs are charged to expense as incurred and the cost of additions and betterments that increase the useful lives of the assets are capitalized. Depreciation and amortization is computed over the estimated useful lives of the related asset type using the straight-line method.

The estimated useful lives for property and equipment are as follows:

Software		2 to 5 years
Computer equipment		2 to 5 years
Furniture, fixtures and office equipment		3 to 5 years
Leasehold improvements		The shorter of the estimated useful life or the remaining term of the agreements, generally ranging from 2 to 15 years

Leasehold improvements are principally comprised of network equipment located at various managed and operated locations, primarily airports, under exclusive, long-term, non-cancelable contracts to provide wireless communication network access.

Equipment and software under capital lease

We lease certain data communications equipment, other equipment and software under capital lease agreements. The assets and liabilities under capital lease are recorded at the lesser of the present value of aggregate future minimum lease payments, including estimated bargain purchase options, or the fair value of the asset under lease. Assets under capital lease are depreciated using the straight-line method over the estimated useful lives of the assets or the term of the lease agreements.

Software development costs

We capitalize costs associated with software developed or obtained for internal use when the preliminary project stage is completed and it is determined that the software will provide significantly enhanced capabilities and modifications. These capitalized costs are included in property and equipment and include external direct cost of services procured in developing or obtaining internal-use software and personnel and related expenses for employees who are directly associated with, and who devote time to internal-use software projects. Capitalization of these costs ceases once the project is substantially complete and the software is ready for its intended use. Once the software is ready for its intended use, the costs are amortized over the useful life of the software. Post-configuration training and maintenance costs are expensed as incurred.

Long-lived assets

Intangible assets consist of acquired venue contracts, technology, advertiser relationships, non-compete agreements and patents and trademarks. We record intangible assets at fair value as of the date of acquisition and amortize these finite-lived assets over the shorter of the contractual life or the estimated useful life on a straight-line basis. We estimate the useful lives of acquired intangible assets based on factors that include the planned use of each acquired intangible asset, the expected pattern of future cash flows to be derived from each acquired intangible asset and contractual periods specified in the related agreements. As such, we account for each of the venue contracts individually. We include amortization of acquired intangibles in amortization of intangible assets in the accompanying consolidated statements of operations.

We perform an impairment review of long-lived assets held and used whenever events or changes in circumstances indicate that the carrying value may not be recoverable. Factors we consider important that could trigger an impairment review include, but are not limited to: significant under-performance relative to projected future operating results, significant changes in the manner of our use of the acquired assets or our overall business and product strategies and significant industry or economic trends. When we determine that the carrying value of a long-lived asset may not be recoverable based upon the existence of one or more of these indicators, we determine the recoverability by comparing the carrying amount of the asset to net future undiscounted cash flows that the asset is expected to generate or other indices of fair value. We would then recognize an impairment charge equal to the amount by which the carrying amount exceeds the fair market value of the asset.

Goodwill

Goodwill represents the excess of the purchase price over the fair value of net assets acquired in connection with the acquisition of Concourse Communication Group, LLC in June 2006, Cloud 9 Wireless, Inc. in August 2012, Endeka Group, Inc. in February 2013, and Electronic Media Systems, Inc. and Advanced Wireless Group, LLC in October 2013.

We test goodwill for impairment in accordance with guidance provided by FASB ASC 350, Intangibles—Goodwill and Other ("ASC 350"). Goodwill is tested for impairment at least annually at the reporting unit level or whenever events or changes in circumstances indicate that goodwill might be impaired. Events or changes in circumstances which could trigger an impairment review include a significant adverse change in legal factors or in the business climate, an adverse action or assessment by a regulator, unanticipated competition, a loss of key personnel, significant changes in the manner of our use of the acquired assets or the strategy for our overall business, significant negative industry or economic trends, or significant underperformance relative to expected historical or projected future results of operations. We perform our impairment test annually as of December 31st.

Entities have the option to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test described in FASB ASC 350. If, after assessing qualitative factors, an entity determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing the two-step impairment test is unnecessary. If deemed necessary, a two-step test is used to identify the potential impairment and to measure the amount of goodwill impairment, if any. The first step is to compare the fair value of the reporting unit with its carrying amount, including goodwill. If the fair value of the reporting unit exceeds its carrying amount, goodwill is considered not impaired; otherwise, there is an indication that goodwill may be impaired and the amount of the loss, if any, is measured by performing step two. Under step two, the impairment loss, if any, is measured by comparing the implied fair value of the reporting unit goodwill with the carrying amount of goodwill.

Currently, we have one reporting unit, one operating segment and one reportable segment. At December 31, 2015 and 2014, all of the goodwill was attributed to our reporting unit. We tested our goodwill for impairment using a market based approach and no impairment was identified as the fair value of our reporting unit was substantially in excess of its carrying amount. To date, we have not recorded any goodwill impairment charges.

Revenue recognition

We generate revenue from several sources including: (i) retail and military customers under subscription plans for month-to-month network access that automatically renew, and retail and military single-use access from sales of hourly, daily or other single-use access plans, (ii) DAS customers that are telecom operators under long-term contracts for access to our DAS at our managed and operated locations, (iii) arrangements with wholesale Wi-Fi customers that provide software licensing, network access, and/or professional services fees, and (iv) 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.

We recognize revenue when an arrangement exists, services have been rendered, fees are fixed or determinable, no significant obligations remain related to the earned fees and collection of the related receivable is reasonably assured. Revenue is presented net of any sales and value added taxes.

Subscription fees from retail and military customers are paid monthly in advance and revenue is deferred for the portions of monthly recurring subscription fees collected in advance. We provide refunds for our retail and military services on a case-by-case basis. These amounts are not significant and are recorded as contra-revenue in the period the refunds are made. Subscription fee revenue is recognized ratably over the subscription period. Revenue generated from retail and military single-use access is recognized when access is provided.

Revenue generated from access to our DAS networks consists of build-out fees and recurring access fees under certain long-term contracts with telecom operators. Build-out fees paid upfront are generally deferred and recognized ratably over the term of the estimated customer relationship period, once the build-out is complete. Periodically, we install and sell Wi-Fi and 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. Minimum monthly access fees for usage of the DAS networks are non-cancellable and generally escalate on an annual basis. These minimum monthly access fees are recognized ratably over the term of the telecom operator agreement. The initial term of our contracts with telecom operators generally range from five to twenty years and the agreements generally contain renewal clauses. Revenue from DAS network access fees in excess of the monthly minimums is recognized when earned.

Services provided to wholesale Wi-Fi partners generally contain several elements including: (i) a term license to use our software to access our Wi-Fi network, (ii) access fees for Wi-Fi network usage, and/or (iii) professional services for software integration and customization and to maintain the Wi-Fi service. The term license, monthly minimum network access fees and professional services are billed on a monthly basis based upon predetermined fixed rates. Once the term license for integration and customization are delivered, the fees from the arrangement are recognized ratably over the remaining term of the service arrangement. The initial term of the license agreements is generally between one to five years and the agreements generally contain renewal clauses. Revenue for Wi-Fi network access fees in excess of the monthly minimum amounts is recognized when earned. All elements within existing service arrangements are generally delivered and earned concurrently throughout the term of the respective service arrangement.

In instances where the minimum monthly Wi-Fi and DAS network access fees escalate over the term of the wholesale service arrangement, an unbilled receivable is recognized when performance is within our control and when we have reasonable assurance that the unbilled receivable balance will be collected.

We adopted the provisions of ASU 2009-13, Revenue Recognition (Topic 605)—Multiple-Deliverable Revenue Arrangements ("ASU 2009-13"), on a prospective basis on January 1, 2011. For multiple-deliverable arrangements entered into prior to January 1, 2011 that are accounted for under ASC 605-25, Revenue Recognition—Multiple-Deliverable Revenue Arrangements, we defer recognition of revenue for the full arrangement and recognize all revenue ratably over the wholesale service period for Wi-Fi platform service arrangements and the term of the estimated customer relationship period for DAS arrangements, as we do not have evidence of fair value for the undelivered elements in the arrangement. For multiple-deliverable arrangements entered into or materially modified after January 1, 2011 that are accounted for under ASC 605-25, we evaluate whether or not separate units of accounting exist and then allocate the arrangement consideration to all units of accounting based on the relative selling price method using estimated selling prices if vendor specific objective evidence and third party evidence is not available. We recognize the revenue associated with the separate units of accounting upon completion of such services or ratably over the wholesale service period for Wi-Fi platform service arrangements and the term of the estimated customer relationship period for DAS arrangements.

Advertising revenue is generated from advertisements on our managed and operated or partner networks. In determining whether an arrangement exists, we ensure that a binding arrangement is in place, such as a standard insertion order or a fully executed customer-specific agreement. Obligations pursuant to our advertising revenue arrangements typically include a minimum number of units or the satisfaction of certain performance criteria. Advertising and other revenue is recognized when the services are performed.

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 consolidated balance sheets. As of December 31, 2015 and December 31, 2014, the Company had $(1,160) and $(443), respectively, of cumulative foreign currency translation adjustments, net of tax, which was $0 as of December 31, 2015 and December 31, 2014 due to the full valuation allowance established against our deferred tax assets, in accumulated other comprehensive loss.

Some of our subsidiaries also enter into transactions and have monetary assets and liabilities that are denominated in a currency other than the entities' respective functional currencies. Gains and losses from the revaluation of foreign currency transactions and monetary assets and liabilities are included in the consolidated statements of operations.

Network access

Network access costs consist primarily of revenue share payments to venue owners where our managed and operated hotspots are located, usage-based fees to our roaming network partners for access to their networks, depreciation of equipment related to network build-out projects in our managed and operated locations, and bandwidth and other Internet connectivity expenses in our managed and operated locations.

Advertising, marketing and promotion costs

Advertising production costs are expensed the first time the advertisement is run. No advertising production costs were capitalized for the years ended December 31, 2015, 2014 and 2013. All other costs of advertising, marketing and promotion are expensed as incurred. Advertising expenses charged to operations totaled $1,703, $1,350 and $2,302 for the years ended December 31, 2015, 2014 and 2013, respectively.

Stock-based compensation

Our stock-based compensation consists of stock options, and restricted stock units ("RSU") granted to employees and non-employees. We have shifted our stock-based compensation from stock options to RSUs and no stock options were granted in 2015.

We recognize stock-based compensation expense in accordance with guidance provided by FASB ASC 718, Compensation—Stock Compensation ("ASC 718"). We measure employee stock-based compensation cost at grant date, based on the estimated fair value of the award and recognize the cost on a straight-line basis, net of estimated forfeitures, over the employee requisite service period. We estimate the fair value of stock options using a Black-Scholes option pricing model. The model requires input of assumptions regarding expected term, expected volatility, dividend yield, and a risk- free interest rate. The weighted average assumptions that were used to calculate the grant date fair value of our employee stock option grants for the following periods are as follows:

	December 31,
	2014			2013
Expected term (years)		6.25			6.25
Expected volatility		48.6	%		49.31	%
Risk-free interest rate		1.8	%		1.34	%
Dividend yield		0	%		0	%

The expected term of employee stock options represents the weighted-average period that the stock options are expected to remain outstanding. In estimating the expected term for options granted to employees, we applied the simplified method from the Security Exchange Commission ("SEC") Staff Accounting Bulletin ("SAB") Topic 14, Share-Based Payment ("SAB Topic 14"), where options are granted at-the-money. Where options were not granted at-the-money, the expected term of employee stock options represents the weighted-average period that the stock options are expected to remain outstanding and is calculated based upon actual historical exercise and post-vesting cancellations, adjusted for expected future exercise behavior.

We determined the fair value of common stock underlying the stock option awards by reference to third party sales of our common stock. We determined the expected volatility assumption using the frequency of daily historical prices of comparable public companies' common stock for a period equal to the expected term of the options in accordance with guidance in ASC 718 and SAB Topic 14. We will continue to monitor peer companies and other relevant factors, including our volatility after there is enough history, used to measure expected volatility for future stock option grants. The risk-free interest rate assumption is based upon observed interest rates on the United States government securities appropriate for the expected term of our employee stock options. The dividend yield assumption is based on our history and expectation of dividend payouts for which no cash dividends have been declared or paid on our common stock, and for which none are anticipated in the foreseeable future.

As stock-based compensation expense recognized in our accompanying consolidated statements of operations is based on awards ultimately expected to vest, the amount has been reduced for estimated forfeitures. ASC 718 requires forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Forfeitures were estimated based on our historical experience and future expectations.

Compensation expense for non-employee stock-based awards is recognized in accordance with ASC 718 and FASB ASC 505, Equity. Stock option awards issued to non-employees are accounted for at fair value using the Black-Scholes option pricing model. Management believes that the fair value of the stock options is more reliably measured than the fair value of the services received. We record compensation expense based on the then-current fair value of the stock options at each financial reporting date. Compensation recorded during the service period is adjusted in subsequent periods for changes in the stock options' fair value until the earlier of the date at which the non-employee's performance is complete or a performance commitment is reached, which is generally when the stock award vests.

Income taxes

We account for income taxes in accordance with FASB ASC 740, Accounting for Income Taxes ("ASC 740"), which requires the recognition of deferred tax assets and liabilities for the future consequences of events that have been recognized in our accompanying consolidated financial statements or tax returns. The measurement of the deferred items is based on enacted tax laws. In the event the future consequences of differences between financial reporting bases and the tax bases of our assets and liabilities result in a deferred tax asset, ASC 740 requires an evaluation of the probability of being able to realize the future benefits indicated by such asset. A valuation allowance related to a deferred tax asset is recorded when it is more likely than not that some portion or the entire deferred tax asset will not be realized. As part of the process of preparing our accompanying consolidated financial statements, we are required to estimate our income taxes in each of the jurisdictions in which we operate. We also assess temporary differences resulting from differing treatment of items, such as deferred revenue, for tax and accounting differences. We record a valuation allowance to reduce the deferred tax assets to the amount of future tax benefit that is more likely than not to be realized. We have classified our deferred tax assets and liabilities as noncurrent on the consolidated balance sheet as of December 31, 2015 and 2014 as we have early adopted ASU 2015-17, Balance Sheet Classification of Deferred Taxes, on a retrospective basis.

ASC 740 prescribes a recognition threshold and measurement methodology to recognize and measure an income tax position taken, or expected to be taken, in a tax return. The evaluation of a tax position is based on a two-step approach. The first step requires an entity to evaluate whether the tax position would "more likely than not" be sustained upon examination by the appropriate taxing authority. The second step requires the tax position be measured at the largest amount of tax benefit that is greater than 50% likely of being realized upon ultimate settlement. In addition, previously recognized benefits from tax positions that no longer meet the new criteria would no longer be recognized. Changes in recognition or measurement are reflected in the period in which the change occurs.

Non-controlling interests

Non-controlling interests are comprised of minority holdings in Chicago Concourse Development Group, LLC ("CCDG") and Boingo Holding Participacoes Ltda ("BHPL").

Under the terms of the LLC agreement for CCDG, we are generally required to distribute annually to the CCDG non-controlling interest holders 30% of allocated net profits less capital expenditures of the preceding year. For the years ended December 31, 2015, 2014 and 2013, we made distributions of $500, $623 and $560, respectively, to non-controlling interest holders of CCDG.

Under the terms of the LLC agreement for BHPL, we attributed profits and losses to the non-controlling interest in BHPL in proportion to their holdings. For the years ended December 31, 2015, 2014 and 2013, we made no distributions to the non-controlling interest holder of BHPL.

Prior to August 4, 2015, we had a 70% ownership of Concourse Communications Detroit, LLC ("CCG Detroit"). On August 4, 2015, we purchased the remaining 30% ownership interest from the non-controlling interest owners for $1,150. We accounted for this transaction as an acquisition of the remaining interest of an entity that had already been majority-owned by the Company. The purchase resulted in a reduction to additional paid-in capital of $1,150 representing excess purchase price over the carrying amount of the non-controlling interests. Under the terms of the limited liability company ("LLC") agreement for CCG Detroit ("Detroit Operating Agreement") profits and losses were allocated to the controlling and non-controlling owners based on specified terms in the Detroit Operating Agreement, which reflected the relative risk and reward of each owner. The profit and loss allocation in the Detroit Operating Agreement specified that the non-controlling owners' allocated profits were limited to the fixed distribution amounts and losses were limited to the non-controlling owners capital account balance with losses in excess of their capital account being fully allocated to the controlling common unit holder. There was no specified term in the Detroit Operating Agreement, but the term of the annual fixed distribution obligation to the non-controlling owner was the same as the term of the venue agreement between CCG Detroit and Detroit Metropolitan Wayne County Airport—which had a seven year initial term with options to extend for an additional four years. We allocated profits and losses in CCG Detroit based on the attribution in the Detroit Operating Agreement. CCG Detroit had generated losses, which reduced the non-controlling owners capital account to zero in 2009 resulting in an allocation to the controlling interest holder all operating losses and deficits created by the annual fixed distributions to the non-controlling interest holder. The fixed distributions were terminated during September 2013 concurrent with the termination of CCG Detroit's agreement with Detroit Metropolitan Wayne County Airport. For the year ended December 31, 2013, we made distribution of $48 to non-controlling interest holders of CCG Detroit.

Net (loss) income per share attributable to common stockholders

Basic net (loss) income per share attributable to common stockholders is calculated by dividing (loss) income attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Diluted net income per share attributable to common stockholders adjusts the basic weighted average number of shares of common stock outstanding for the potential dilution that could occur if stock options and RSUs were exercised or converted into common stock. Our common stockholders are not entitled to receive any dividends.

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. In 2014, we updated our presentation of retail and wholesale revenue sources to provide increased visibility into the revenue streams that are the focus of our current and future operational and development efforts. Our retail revenue sources were previously differentiated based on our retail plan types—subscription or single-use. We believe that it is more relevant to differentiate our individual users based on the nature of the users—retail users who purchase Internet access at our managed and operated hotspots and select partner locations or military users who purchase Internet access or IPTV services for individual use on military bases. We also previously combined our wholesale DAS and Wi-Fi revenues and we believe that it is better to disaggregate these wholesale product revenues going forward by DAS and Wi-Fi given the current development of these products. The revenue sources are consistent with how our chief operating decision maker monitors and reviews our operations.

The following is a summary of our revenue by primary revenue source:

	Year Ended December 31,
	2015		2014		2013
Revenue:
DAS	$	46,455	$	38,259	$	32,681
Retail		31,763		40,336		43,194
Wholesale—Wi-Fi		21,923		15,209		17,261
Military		19,898		4,486		1,260
Advertising and other		19,587		21,007		12,350

Total revenue	$	139,626	$	119,297	$	106,746

Recent accounting pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which requires lessees to recognize assets and liabilities for all leases with lease terms of more than 12 months on the balance sheet. Under the new guidance, 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. The standard is effective for interim and annual periods beginning after December 15, 2018. Early adoption is permitted for all entities on a modified retrospective basis, with elective reliefs. We are currently evaluating the expected impact of this new standard.

In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes, which requires that all deferred tax assets and liabilities, along with any related valuation allowance, for each tax-paying jurisdiction within each tax-paying component be classified as noncurrent on the balance sheet. The standard is effective for interim and annual periods beginning after December 15, 2016. Early adoption is permitted for all entities on a retrospective or prospective basis. We early adopted the new standard on a retrospective basis as of December 31, 2015.

In September 2015, the FASB issued ASU 2015-16, Simplifying the Accounting for Measurement Period Adjustments, which eliminates the requirement to restate prior period financial statements for measurement period adjustments. The standard is effective for interim and annual periods beginning after December 15, 2015. The new standard must be applied prospectively to measurement period adjustments that occur after the effective date. We do not expect that this standard will have a material impact on our consolidated financial statements.

In April 2015, the FASB issued ASU 2015-05, Customer's Accounting for Fees Paid in a Cloud Computing Arrangement, which provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the arrangement for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The standard is effective for annual periods beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted for all entities. An entity may choose to adopt the new standard either retrospectively or prospectively. We do not expect that this standard will have a material impact on our consolidated financial statements.

In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, which requires entities to present debt issuance costs related to a note as a direct deduction from the face amount of that note, similar to the presentation of debt discounts. The costs will continue to be amortized to interest expense. In August 2015, the FASB issued ASU 2015-15, Interest—Imputation of Interest (Subtopic 835-30), which amends subtopic 835-30 to include that the SEC would not object to the deferral and presentation of debt issuance costs as an asset and subsequent amortization of the asset ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. The standard will be effective for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted. An entity must adopt the new standard retrospectively for all prior periods presented in the financial statements. We do not expect that this standard will have a material impact on our consolidated financial statements. As of December 31, 2015 and 2014, we have classified debt issuance costs related to our revolving line of credit of $197 and $178, respectively, within prepaid expenses and other current assets, and $372 and $514, respectively, within other assets in the consolidated balance sheets.

In February 2015, the FASB issued ASU 2015-02, Consolidation—Amendments to the Consolidation Analysis, which amends the current consolidation guidance and ends the deferral granted to investment companies from applying the variable interest entity guidance. The standard will be effective for fiscal years beginning after December 15, 2015. Early adoption is permitted. We do not expect that this standard will have a material impact on our consolidated financial statements.

In August 2014, the FASB issued ASU 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern, which explicitly requires management to assess an entity's ability to continue as a going concern in connection with each annual and interim period. Management will assess if there is substantial doubt about an entity's ability to continue as a going concern within one year of the date the financial statements are issued. Disclosures will be required if conditions give rise to substantial doubt. The standard will be effective for the first annual period ending after December 15, 2016. Early adoption is permitted. We are currently evaluating the expected impact of this new standard.

In June 2014, the FASB issued ASU 2014-12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period, which requires that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. As such, the performance target should not be reflected in estimating the grant-date fair value of the award. Compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the period(s) for which the requisite service has already been rendered. If the performance target becomes probable of being achieved before the end of the requisite service period, the remaining unrecognized compensation cost should be recognized prospectively over the remaining requisite service period. The standard will be effective for fiscal years and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. An entity may choose to adopt the new standard either prospectively or retrospectively. This standard will not have any impact on our consolidated financial statements as we have not issued any share-based payments with performance targets that could be achieved after the requisite service period.

In May 2014, the FASB issued ASU 2014-09, Revenue From Contracts with Customers, which is intended to improve and converge the financial reporting requirements for revenue from contracts with customers between U.S. GAAP and International Accounting Standards. In accordance with this new standard, an entity would recognize revenue to depict the transfer of promised goods or services. The standard establishes a five-step model and related application guidance, which will replace most existing revenue recognition guidance in U.S. GAAP. The FASB has subsequently issued several proposals to clarify guidance to be applied. In August 2015, the FASB issued ASU 2015-14, Revenue From Contracts with Customers (Topic (606): Deferral of the Effective Date, to defer the effective date of the new revenue standard by one year. The standard will be effective for annual and interim periods in fiscal years beginning after December 15, 2017. The FASB also agreed to allow entities to choose to adopt the standard as of the original effective date. An entity may choose to adopt the new standard either retrospectively or through a cumulative effect adjustment as of the start of the first period for which it applies the new standard. We have not yet selected an effective date or a transition method and are currently evaluating the expected impact of this new standard, including proposed amendments, on our reporting of revenue contracts in our consolidated financial statements and related disclosures.