| Organization and Significant Accounting Policies | Organization and Significant Accounting Policies Organization and Business DexCom, Inc. is a medical device company focused on the design, development and commercialization of continuous glucose monitoring, or CGM, systems for ambulatory use by people with diabetes and by healthcare providers. Unless the context requires otherwise, the terms “we,” “us,” “our,” the “company,” or “DexCom” refer to DexCom, Inc. and its subsidiaries. Basis of Presentation and Principles of Consolidation The consolidated financial statements include the accounts of DexCom, Inc. and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We have reclassified certain amounts previously reported in our financial statements to conform to the current presentation. The functional currencies of our international subsidiaries are generally the local currencies. We translate the financial statements of our foreign subsidiaries into U.S. dollars using period-end exchange rates for assets and liabilities and average exchange rates for each period for revenue, costs and expenses. We include translation-related adjustments in comprehensive loss and in accumulated other comprehensive income (loss) in the equity section of our balance sheet. Gains and losses resulting from certain intercompany transactions as well as transactions with customers and vendors that are denominated in currencies other than the functional currency of each entity give rise to foreign exchange gains or losses that we record in interest and other income (expense), net in our statements of operations. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires us to make certain estimates and assumptions that affect the amounts reported in our financial statements and the disclosures made in the accompanying notes. Areas requiring significant estimates include pharmacy rebates, transaction price, net accounts receivable, excess or obsolete inventories and the valuation of inventory, and accruals for litigation contingencies. Despite our intention to establish accurate estimates and use reasonable assumptions, actual results may differ from our estimates. Fair Value Measurements The authoritative guidance establishes a fair value hierarchy that is based on the extent and level of judgment used to estimate the fair value of assets and liabilities. In general, the authoritative guidance requires us to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. An asset or liability’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the measurement of its fair value. The three levels of input defined by the authoritative guidance are as follows: Level 1—Unadjusted quoted prices that are available in active markets for identical assets or liabilities. Level 2—Inputs other than quoted prices included in Level 1 that are observable, either directly or indirectly, through correlation with market data. These include quoted prices in active markets for similar assets or liabilities; quoted prices for identical or similar assets or liabilities in markets that are not active; and inputs to valuation models or other pricing methodologies that do not require significant judgment because the inputs used in the model, such as interest rates and volatility, can be corroborated by readily observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the determination of fair value. Level 3 assets and liabilities include those whose fair values are determined using pricing models, discounted cash flow methodologies, or similar valuation techniques and significant judgment or estimation. We carry our marketable securities at fair value. We carry our other financial instruments, such as cash and cash equivalents, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued liabilities, at cost, which approximates the related fair values due to the short-term maturities of these instruments. For more information see Note 3, “Fair Value Measurements.” Cash and Cash Equivalents We consider highly liquid investments with a maturity of 90 days or less at the time of purchase to be cash equivalents. Marketable Securities We have classified our marketable securities with remaining maturity at purchase of more than three months and remaining maturities of one year or less as short-term marketable securities. We have also classified marketable securities with remaining maturities of greater than one year as short-term marketable securities based upon our ability and intent to use any and all of those marketable securities to satisfy the liquidity needs of our current operations. We calculate realized gains or losses on our marketable securities using the specific identification method. We carry our marketable debt securities at fair value with unrealized gains and losses reported as a separate component of stockholders’ equity in our balance sheets and included in comprehensive loss. Realized gains and losses on marketable debt securities are included in interest and other income (expense), net in our statements of operations. We carry our marketable equity securities at fair value with realized and unrealized gains and losses reported in income on equity investments in our statements of operations. We invest in various types of debt securities, including debt securities in government-sponsored entities, corporate debt securities, U.S. Treasury securities and commercial paper. We do not generally intend to sell these investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases, which may be at maturity. See Note 3, “Fair Value Measurements” and Note 4, “Balance Sheet Details – Short-Term Marketable Securities ” for more information on our marketable debt securities and our marketable equity securities. Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are generally recorded at the invoiced amount for Distributors and at net realizable value for Direct customers, which is determined using estimates of claim denials and historical reimbursement experience without regard to aging category. Accounts receivable are not interest bearing. We evaluate the creditworthiness of significant customers and generally do not require collateral from our customers. We maintain an allowance for doubtful accounts for potential credit losses. Uncollectable accounts are written off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a customer account is uncollectable. Generally, receivable balances greater than one year past due are deemed uncollectable. Concentration of Credit Risk and Significant Customers Financial instruments which potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents, short-term investment securities, and accounts receivable. We limit our exposure to credit loss by placing our cash and investments with high credit quality financial institutions. We have also established guidelines regarding diversification of our investments and their maturities that are designed to maintain principal and maximize liquidity. We review these guidelines periodically and modify them to take advantage of trends in yields and interest rates and changes in our operations and financial position. Two of our distributors are significant customers. Each of them accounted for more than 10% of revenue in each of the past three fiscal years and each of them accounted for more than 10% of accounts receivable as of the end of the past two fiscal years. Distributor A accounted for 15% , 16% and 14% of our revenues for the twelve months ended December 31, 2018 , 2017 and 2016 , respectively. Distributor B accounted for 12% , 14% and 17% of our revenues for the twelve months ended December 31, 2018 , 2017 and 2016 , respectively. Distributor A and Distributor B accounted for 19% and 15% , respectively, of accounts receivable as of December 31, 2018 and 18% and 12% , respectively, of accounts receivable as of December 31, 2017 . Inventory Inventory is valued at the lower of cost or net realizable value on a part-by-part basis that approximates first in, first out. We record adjustments to inventory for potentially excess, obsolete or scrapped goods in order to state inventory at net realizable value. Factors influencing these adjustments include inventories on hand and on order compared to estimated future usage and sales for existing and new products, as well as judgments regarding quality control testing data and assumptions about the likelihood of scrap and obsolescence. Once written down the adjustments are considered permanent and are not reversed until the related inventory is sold or disposed of. Our products require customized products and components that currently are available from a limited number of sources. We purchase certain components and materials from single sources due to quality considerations, costs or constraints resulting from regulatory requirements. Property and Equipment Property and equipment is stated at cost less accumulated depreciation. We calculate depreciation using the straight-line method over the estimated useful lives of the assets. Estimated useful lives are generally three years for computer software and hardware, four to 15 years for machinery and equipment, and five years for furniture and fixtures. Leasehold improvements and assets acquired through a build-to-suit arrangement are amortized over the shorter of the estimated useful lives of the assets or the remaining lease term. We include the amortization of assets that are recorded under capital leases in depreciation expense. We review property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. We estimate the recoverability of the asset by comparing the carrying amount to the future undiscounted cash flows that we expect the asset to generate. We estimate the fair value of the asset based on the present value of future cash flows for those assets. If the carrying value of an asset exceeds its estimated fair value, we would record an impairment loss equal to the difference. Goodwill We record goodwill when the fair value of consideration transferred in a business combination exceeds the fair value of the identifiable assets acquired and liabilities assumed. Goodwill and other intangible assets that have indefinite useful lives are not amortized, but we test them annually for impairment in the fourth quarter of our fiscal year and whenever events or changes in circumstances indicate that it is more likely than not that the fair value is less than the carrying value. Events that would indicate impairment and trigger an interim impairment assessment include, but are not limited to, current economic and market conditions, including a decline in market capitalization, a significant adverse change in legal factors, business climate or operational performance of the business, and an adverse action or assessment by a regulator. We perform our goodwill impairment analysis at the reporting unit level, which aligns with DexCom’s reporting structure and the availability of discrete financial information. We perform the first step of our annual impairment analysis by either comparing a reporting unit’s estimated fair value to its carrying amount or doing a qualitative assessment of a reporting unit’s fair value from the last quantitative assessment to determine if there is potential impairment. We may do a qualitative assessment when the results of the previous quantitative test indicated the reporting unit’s estimated fair value was significantly in excess of the carrying value of its net assets and we do not believe there have been significant changes in the reporting unit’s operations that would significantly decrease its estimated fair value or significantly increase its net assets. If a quantitative assessment is performed the evaluation includes management estimates of cash flow projections based on internal future projections and/or use of a market approach by looking at market values of comparable companies. Key assumptions for these projections include revenue growth, future gross margin and operating margin growth, and weighted cost of capital and terminal growth rates. The revenue and margin growth are based on increased sales of new and existing products as we maintain investments in research and development. Additional assumed value creators may include increased efficiencies from capital spending. The resulting cash flows are discounted using a weighted average cost of capital. Operating mechanisms and requirements to ensure that growth and efficiency assumptions will ultimately be realized are also considered in the evaluation, including the timing and probability of regulatory approvals for our products to be commercialized. We also consider DexCom’s market capitalization as a part of our analysis. If the estimated fair value of a reporting unit exceeds the carrying amount of the net assets assigned to that unit, goodwill is not impaired and no further analysis is required. If the carrying value of the net assets assigned to a reporting unit exceeds the estimated fair value of the unit, we perform the second step of the impairment test. In this step we allocate the fair value of the reporting unit calculated in step one to all of the assets and liabilities of that unit, as if we had just acquired the reporting unit in a business combination. The excess of the fair value of the reporting unit over the total amount allocated to the assets and liabilities represents the implied fair value of goodwill. If the carrying amount of a reporting unit’s goodwill exceeds its implied fair value, we would record an impairment loss equal to the difference. We recorded no goodwill impairment charges for the twelve months ended December 31, 2018 , 2017 or 2016 . There were no accumulated impairment losses for goodwill at December 31, 2016 . The change in goodwill for the twelve months ended December 31, 2017 consisted of translation adjustments on our foreign currency denominated goodwill. The change in goodwill for the twelve months ended December 31, 2018 consisted of goodwill we recorded for acquisitions that were not significant, individually or in the aggregate, and translation adjustments on our foreign currency denominated goodwill. Intangible Assets and Other Long-Lived Assets We amortize intangible assets with a finite life, such as acquired technology, customer relationships, trade names and trademarks, on a straight-line basis over their estimated useful lives, which range from two to five years. We review intangible assets that have finite lives and other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. We estimate the fair value of the asset based on the present value of future cash flows for those assets. If the carrying value of an asset exceeds its estimated fair value, we would record an impairment loss equal to the difference. Income Taxes We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. We recognize deferred tax assets to the extent that we believe that these assets are more likely than not to be realized, which requires significant judgment. The realization of deferred tax assets is dependent, in part, upon future taxable income. In assessing whether our deferred tax assets will be realized, we consider all available evidence, both positive and negative. Such evidence includes historical earnings, future reversals of existing taxable temporary differences, estimates of future taxable income, and the feasibility of ongoing tax planning strategies. We have recorded a full valuation allowance on our net deferred tax asset balances for all periods presented because of the uncertainty related to utilization of our deferred tax assets. We record uncertain tax positions in accordance with ASC 740 on the basis of a two-step process in which (1) we determine whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, we recognize the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. We file federal and state income tax returns in the United States and income tax returns in various other foreign jurisdictions with varying statutes of limitations. Due to net operating losses incurred, our income tax returns from inception to date are subject to examination by taxing authorities. We recognize interest expense and penalties related to income tax matters, including unrecognized tax benefits, as a component of income tax expense. Warranty Accrual Estimated warranty costs associated with a product are recorded at the time revenue is recognized. We estimate future warranty costs by analyzing historical warranty experience for the timing and amount of returned product, and expectations for future warranty activity based on changes and improvements to the product or process that are in place or will be in place in the future. We evaluate these estimates on at least a quarterly basis to determine the continued appropriateness of our assumptions. Loss Contingencies If the potential loss from a claim or legal proceeding is considered probable and the amount can be reasonably estimated, we record a liability and an expense for the estimated loss and disclose it in our financial statements if it is significant. If we determine that a loss is possible and the range of the loss can be reasonably determined, then we disclose the range of the possible loss. Significant judgment is required in the determination of whether a potential loss is probable, reasonably possible, or remote as well as in the determination of whether a potential exposure is reasonably estimable. Comprehensive Loss Comprehensive loss consists of two elements, net loss and other comprehensive income (loss). We report all components of comprehensive loss, including net loss, in our financial statements in the period in which they are recognized. Total comprehensive loss is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources. We report net loss and the components of other comprehensive income (loss), including foreign currency translation adjustments and unrealized gains and losses on marketable securities, net of their related tax effect to arrive at total comprehensive loss. Revenue Recognition We generate our revenue from the sale of our durable CGM systems and disposable sensors (the Components). Our durable systems include a reusable transmitter and receiver. Disposable sensors are sold separately. We also provide free-of-charge software and mobile applications for use with our durable systems and disposable sensors. The initial durable system price is generally not dependent upon the subsequent purchase of any amount of disposable sensors. We sell our durable systems and disposable sensors through two main sales channels: 1) directly to customers who use our products or organizations (the Direct Channel) and 2) to distribution partners who resell our products (the Distributor Channel). In the Direct Channel, we sell our durable systems and disposable sensors to customers who use our products and we receive payment directly from customers who use our products, organizations and third-party payors. Third-party payors primarily include commercial insurance companies and federal and state agencies (under Medicare and Medicaid programs). We adopted ASC Topic 606 effective January 1, 2018 using the modified retrospective method. We applied the practical expedient permitted under ASC Topic 606 to those contracts that were not completed as of the date of initial adoption. Results for reporting periods after January 1, 2018 are presented under ASC Topic 606, while prior period amounts are not adjusted and continue to be reported in accordance with legacy accounting guidance under ASC Topic 605. Our revenue recognition policies under ASC Topic 606 are explained below. Policy elections and practical expedients taken • We report revenue net of taxes collected from customers, which are subsequently remitted to governmental authorities; • We account for shipping and handling activities that are performed after a customer has obtained control of a good as fulfillment costs rather than as separate performance obligations; • We do not assess whether promised goods or services are performance obligations if they are immaterial in the context of the contract with the customer; and • If we expect, at contract inception, that the period between the transfer of control and corresponding payment from the customer will be one year or less, we do not adjust the amount of consideration for the effects of a significant financing component. Contracts and performance obligations We consider customer purchase orders, which in most cases are governed by agreements with distributors or third-party payors, to be contracts with a customer. For each contract, we consider the obligation to transfer Components to the customer, each of which are distinct, to be separate performance obligations. Components are individually priced and can be purchased separately or bundled in a contract. We also provide free-of-charge software, mobile applications and updates for our DexCom Share ® remote monitoring system. The standalone selling prices of our free-of-charge software, mobile applications and updates are based on an expected cost plus a margin approach. Transaction price Transaction price for the Components reflects the net consideration to which we expect to be entitled. Transaction price is typically based on contracted rates less any estimates of claim denials and historical reimbursement experience, which would include current and future expectations regarding reimbursement contracts, guidelines and payor mix, and less estimated variable consideration adjustments. Variable consideration Rebates. We estimate reductions to our revenues for rebates paid to payors and healthcare providers in the United States. Rebates are based on contractual arrangements or statutory requirements, which may vary by product, payor and individual payor plans. Our estimates are based on products sold, historical payor mix and, as available, known market events or trends and channel inventory data. We also take into consideration, as available, new information regarding changes in programs’ regulations and guidelines that would impact the amount of the actual rebates and/or our expectations regarding future payor mix for these programs. Product Returns. We generally provide a “ 30 -day money back guarantee” program whereby first-time end-user customers may return the durable system. In accordance with the terms of their distribution agreements, most distributors do not have rights of return outside of our limited warranty. The distributors typically have a limited time frame to notify us of any missing, damaged, defective or non-conforming products. Our returns have historically been immaterial. Revenue recognition We recognize revenue when control is transferred to our customers. The timing of revenue recognition is based on the satisfaction of performance obligations. Substantially all of the performance obligations associated with our durable systems and disposable sensors are satisfied at a point in time, which typically occurs at shipment of our products. Terms of direct and distributor orders are generally Freight on Board (FOB) shipping point for U.S. orders or Free Carrier (FCA) shipping point for international orders. For certain of our distributors, control transfers at delivery of the product to the customer. In cases where our free-of-charge software, mobile applications and updates are deemed to be separate performance obligations, revenue is recognized over time on a ratable basis over the estimated life of the related hardware component. Our sales of the receiver and transmitter components of our CGM systems include an assurance-type warranty which is accounted for based on the cost accrual method recognized as expense when the products are sold and is not considered a separate performance obligation. Contract balances The timing of revenue recognition, billing and cash collections results in trade receivables and deferred revenue on our balance sheets. We recognize a receivable in the period in which our right to the consideration is unconditional. We generally do not have any contracts or performance obligations with a term of more than one year. Our contracts with customers do not typically include extended payment terms. Payment terms vary by contract type and type of customer and generally range from 30 to 90 days. Accounts receivable as of December 31, 2018 included unbilled accounts receivable of $5.1 million . Unbilled accounts receivable consists of revenue recognized for Components we have delivered but not yet invoiced to customers. We expect to invoice and collect all unbilled accounts receivable within twelve months. Substantially all of our deferred revenue as of December 31, 2018 is associated with certain of our free-of-charge software and mobile applications and will be recognized during 2019 . During the twelve months ended December 31, 2018 , we recognized revenue of $1.9 million that was recorded as deferred revenue as of December 31, 2017 . Deferred cost of sales Deferred cost of sales are associated with sales for which revenue recognition criteria are not met but product has shipped and released from inventory. These costs are recognized in cost of sales when the associated revenue is recognized. Deferred cost of sales are included in prepaid and other current assets in our balance sheets. Incentive compensation costs We generally expense incentive compensation associated with our internal sales force when incurred because the amortization period for such costs, if capitalized, would have been one year or less. We record these costs in selling, general and administrative expense in our statement of operations. Product Shipment Costs We record the amounts we charge our customers for the shipping and handling of our products in revenue and we record the related costs as cost of sales in our statements of operations. Research and Development We expense all costs of research and development as we incur them. Our research and development expenses primarily consist of engineering and research expenses related to our continuous glucose monitoring technology, clinical trials, regulatory expenses, quality assurance programs, materials and products for clinical trials. Research and development expenses primarily consist of employee compensation, including salary, fringe benefits, share-based compensation, and temporary employee expenses. We also incur significant expenses to operate our clinical trials that include clinical site reimbursement, clinical trial product, and associated travel expenses. Our research and development expenses also include fees for design services, contractors, and development materials. Our CGM systems include certain software that we develop. We expense software development costs as we incur them until technological feasibility has been established, at which time we capitalize development costs until the product is available for general release to customers. To date, our software has been available for general release concurrent with the establishment of technological feasibility and, accordingly, we have not capitalized any development costs. Advertising Costs We expense all advertising costs as we incur them to selling, general and administrative expenses. Advertising expense was $25.4 million , $21.9 million and $11.9 million for the twelve months ended December 31, 2018 , 2017 and 2016 , respectively. Leases We review all leases for capital or operating classification at their inception. We use our incremental borrowing rate in the assessment of lease classification and define the initial lease term to include the construction build-out period but to exclude lease extension periods when we are not reasonably certain to exercise our extension option. We conduct our operations primarily under operating leases. For leases that contain rent escalations, we record the total rent payable during the lease term, as defined above, to rent expense on a straight-line basis over the term of the lease. We record the difference between amounts paid under the lease agreements and the straight-line rent expense as deferred rent in our balance sheets. Share-Based Compensation Share-based compensation expense is measured at the grant date based on the estimated fair value of the award and is recognized straight-line over the requisite service period of the individual grants, which typically equals the vesting period. Shared-based compensation arrangements include time-based and performance/market-based Restricted Stock Units, or RSUs, and purchases of common stock at a discount under our Employee Stock Purchase Plan, or ESPP. We estimate the fair value of time-based RSUs using the closing market price of our common stock on the date of grant. We estimate the fair value of performance/market-based RSUs using a Monte Carlo simulation model and adjust share-based compensation expense based on the expected achievement of the related performance conditions at the end of each reporting period. We estimate the fair value of ESPP purchase rights using the Black-Scholes option pricing model. The model uses assumptions that include expected volatility, expected term, dividends, and the risk-free interest rate. The expected volatility is based on the historical volatility of our common stock over the expected term of the awards. The expected term is based on the terms and conditions of the ESPP stock awards. The expected dividend yield is zero because we have never declared or paid cash dividends on our common stock and do not anticipate paying dividends in the foreseeable future. The risk-free interest rate is based on U.S. Treasury securities with remaining terms similar to the expected term of the stock awards. We account for forfeitures as they occur by reversing any share-based compensation expense related to awards that will not vest. Net Income (Loss) Per Share Basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net income (loss) per share is computed using the weighted average number of common shares outstanding during the period and, when dilutive, potential common share equivalents. Common share equivalents that we calculate using the treasury stock method include outstanding stock options and unvested RSUs that are settleable in shares of common stock and potential common shares from convertible securities that we intend to settle using a combination of shares of our common stock and cash. Common share equivalents that we calculate using the if-converted method include potential common shares from convertible securities that we intend to settle using only shares of our common stock. Because we reported net losses for the twelve months ended December 31, 2018 , 2017 and 2016 , all potentially dilutive common shares have been excluded from the computation of the diluted net loss per share for those periods as the effect would have been anti-dilutive. Outstanding anti-dilutive securities not included in the diluted net loss per share attributable to common stockholders calculations were |
