Document and Entity Information
Document and Entity Information | 9 Months Ended |
Sep. 30, 2018 | |
Document and Entity Information | |
Entity Registrant Name | Inspire Medical Systems, Inc. |
Entity Central Index Key | 1,609,550 |
Document Type | S1 |
Document Period End Date | Sep. 30, 2018 |
Amendment Flag | false |
Entity Filer Category | Non-accelerated Filer |
Entity Small Business | true |
Entity Emerging Growth Company | true |
Entity Ex Transition Period | false |
BALANCE SHEETS
BALANCE SHEETS $ in Thousands | Dec. 31, 2016USD ($) |
Current assets: | |
Cash and cash equivalents | $ 6,685 |
Short-term investments | 0 |
Accounts receivable, net of allowances of $44 and $47, respectively | 2,091 |
Inventories | 3,355 |
Prepaid expenses and other assets | 118 |
Total current assets | 12,249 |
Property and equipment, cost | 1,548 |
Less: accumulated depreciation | (681) |
Property and equipment, net | 867 |
Total assets | 13,116 |
Current liabilities: | |
Accounts payable | 1,173 |
Accrued expenses | 2,704 |
Accrued interest | 103 |
Current portion of notes payable | 3,310 |
Total current liabilities | 7,290 |
Notes payable | 12,381 |
Preferred stock warrants | 53 |
Total long-term liabilities | 12,434 |
Stockholders' (deficit) equity | |
Preferred Stock, $0.001 par value, 10,000,000 shares and 76,894,620 shares authorized at September 30, 2018 and December 31, 2017, respectively; none and 76,235,050 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively | 94,138 |
Common Stock, $0.001 par value per share; 85,000,000 and 110,000,000 shares authorized at December 31, 2016 and 2017, respectively; 1,145,238 and 1,272,360 issued and outstanding at December 31, 2016 and 2017, respectively | 1 |
Additional paid -in capital | 6,827 |
Accumulated other comprehensive loss | 0 |
Accumulated deficit | (107,574) |
Total stockholders' equity | (6,608) |
Total liabilities and stockholders' equity | $ 13,116 |
BALANCE SHEETS (Parenthetical)
BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Statement of Financial Position [Abstract] | |||
Accounts receivable, allowances (in dollars) | $ 47 | $ 47 | $ 44 |
Preferred shares, par value (in dollars per share) | $ 0.001 | $ 0.001 | $ 0.001 |
Preferred shares, authorized (in shares) | 10,000,000 | 76,894,620 | 58,354,472 |
Preferred shares, issued (in shares) | 0 | 76,235,050 | 57,986,873 |
Preferred shares, outstanding (in shares) | 0 | 76,235,050 | 57,986,873 |
Common stock, par value (in dollars per share) | $ 0.001 | $ 0.001 | $ 0.001 |
Common stock, authorized shares | 200,000,000 | 110,000,000 | 85,000,000 |
Common stock, issued shares | 21,391,590 | 1,272,360 | 1,145,238 |
Common stock, outstanding shares | 21,391,590 | 1,272,360 | 1,145,238 |
STATEMENTS OF OPERATIONS AND CO
STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Income Statement [Abstract] | |||||
Revenues | $ 34,034 | $ 18,610 | $ 28,567 | $ 16,427 | $ 8,012 |
Cost of goods sold | 6,863 | 4,137 | 6,018 | 3,905 | 2,809 |
Gross profit | 27,171 | 14,473 | 22,549 | 12,522 | 5,203 |
Operating expenses: | |||||
Selling and marketing | 31,913 | 19,566 | 28,552 | 20,019 | 15,291 |
Research and development | 5,236 | 4,512 | 6,194 | 7,091 | 7,079 |
General and administrative | 5,503 | 2,552 | 3,806 | 2,665 | 2,631 |
Total operating expenses | 42,652 | 26,630 | 38,552 | 29,775 | 25,001 |
Operating loss | (15,481) | (12,157) | (16,003) | (17,253) | (19,798) |
Other expense (income): | |||||
Interest income | (1,049) | (119) | (203) | (57) | (66) |
Interest expense | 2,615 | 1,224 | 1,753 | 1,303 | 1,564 |
Other expense (income), net | 3 | (2) | (42) | 29 | 41 |
Loss before income taxes | (17,050) | (13,260) | (17,511) | (18,528) | (21,337) |
Income taxes | 0 | 0 | 0 | 0 | |
Net loss | (17,050) | (13,260) | (17,511) | (18,528) | (21,337) |
Other comprehensive loss: | |||||
Unrealized gains on short-term investments | (26) | 0 | 0 | 0 | 14 |
Total comprehensive loss | $ (17,076) | $ (13,260) | $ (17,511) | $ (18,528) | $ (21,323) |
Net loss per share, basic and diluted | $ (1.40) | $ (11.45) | $ (14.88) | $ (16.90) | $ (20.74) |
Weighted average common shares used to compute net loss per share, basic and diluted | 12,137,512 | 1,158,548 | 1,176,650 | 1,096,013 | 1,027,925 |
STATEMENTS OF STOCKHOLDERS' (DE
STATEMENTS OF STOCKHOLDERS' (DEFICIT) EQUITY - USD ($) $ in Thousands | Common Stock | Additional paid-in capital | Convertible Preferred Stock | Accumulated Other Comprehensive Loss | Accumulated Deficit | Total |
Balance at Dec. 31, 2014 | $ 1 | $ 6,043 | $ 81,513 | $ (14) | $ (67,709) | $ 19,834 |
Balance (in shares) at Dec. 31, 2014 | 1,014,614 | |||||
Balance (in shares) at Dec. 31, 2014 | 48,603,909 | |||||
Increase (Decrease) in Stockholders' Equity [Roll Forward] | ||||||
Stock options exercised | 42 | $ 42 | ||||
Stock options exercised (in shares) | 21,545 | 21,545 | ||||
Stock based compensation expense | 305 | $ 305 | ||||
Unrealized gains on investments | $ 14 | 14 | ||||
Net loss | (21,337) | (21,337) | ||||
Balance at Dec. 31, 2015 | $ 1 | 6,390 | $ 81,513 | (89,046) | (1,142) | |
Balance (in shares) at Dec. 31, 2015 | 1,036,159 | |||||
Balance (in shares) at Dec. 31, 2015 | 48,603,909 | |||||
Increase (Decrease) in Stockholders' Equity [Roll Forward] | ||||||
Stock options exercised | 189 | $ 189 | ||||
Stock options exercised (in shares) | 109,079 | 109,079 | ||||
Exercise of Series C preferred stock warrants | $ 277 | $ 277 | ||||
Exercise of Series C preferred stock warrants (in shares) | 258,880 | |||||
Sale of Series F convertible preferred stock, net issuance costs | $ 12,348 | 12,348 | ||||
Shares issued during the period | 9,124,084 | |||||
Stock based compensation expense | 248 | 248 | ||||
Net loss | (18,528) | (18,528) | ||||
Balance at Dec. 31, 2016 | $ 1 | 6,827 | $ 94,138 | (107,574) | $ (6,608) | |
Balance (in shares) at Dec. 31, 2016 | 1,145,238 | 1,145,238 | ||||
Balance (in shares) at Dec. 31, 2016 | 57,986,873 | 57,986,873 | ||||
Increase (Decrease) in Stockholders' Equity [Roll Forward] | ||||||
Stock options exercised | 235 | $ 235 | ||||
Stock options exercised (in shares) | 127,122 | 127,122 | ||||
Sale of Series F convertible preferred stock, net issuance costs | $ 24,968 | $ 24,968 | ||||
Shares issued during the period | 18,248,177 | |||||
Stock based compensation expense | 243 | 243 | ||||
Net loss | (17,511) | (17,511) | ||||
Balance at Dec. 31, 2017 | $ 1 | $ 7,305 | $ 119,106 | $ (125,085) | $ 1,327 | |
Balance (in shares) at Dec. 31, 2017 | 1,272,360 | 1,272,360 | ||||
Balance (in shares) at Dec. 31, 2017 | 76,235,050 | 76,235,050 | ||||
Increase (Decrease) in Stockholders' Equity [Roll Forward] | ||||||
Stock options exercised (in shares) | 227,114 | |||||
Net loss | $ (17,050) | |||||
Balance at Sep. 30, 2018 | $ 98,311 | |||||
Balance (in shares) at Sep. 30, 2018 | 21,391,590 | |||||
Balance (in shares) at Sep. 30, 2018 | 0 |
STATEMENTS OF STOCKHOLDERS' (_2
STATEMENTS OF STOCKHOLDERS' (DEFICIT) EQUITY (Parenthetical) - USD ($) $ in Thousands | 12 Months Ended | |
Dec. 31, 2017 | Dec. 31, 2016 | |
Convertible Preferred Stock | ||
Sale of Series F convertible preferred stock issuance costs | $ 32 | $ 152 |
STATEMENTS OF CASH FLOWS
STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Operating activities | |||
Net loss | $ (17,511) | $ (18,528) | $ (21,337) |
Adjustments to reconcile net loss: | |||
Depreciation and amortization | 285 | 103 | 120 |
Accretion of debt discount | 315 | 180 | 50 |
Stock-based compensation expense | 243 | 248 | 305 |
Change in the fair value of preferred stock warrants | 100 | (195) | 12 |
Changes in operating assets and liabilities: | |||
Accounts receivable | (1,767) | (760) | (261) |
Inventories | (315) | 612 | (1,514) |
Prepaid expenses and other assets | (308) | 88 | (118) |
Accounts payable | 1,825 | (480) | 418 |
Accrued expenses | 1,342 | 783 | 71 |
Net cash used in operating activities | (15,791) | (17,949) | (22,254) |
Investing activities | |||
Purchases of property and equipment | (412) | (306) | (346) |
Purchases of short-term investments | (8,969) | 0 | 0 |
Proceeds from sales or maturities of short-term investments | 1,781 | 0 | 23,910 |
Net cash used in investing activities | (7,600) | (306) | 23,564 |
Financing activities | |||
Payments of notes payable | 0 | 0 | (7,000) |
Proceeds from issuance of notes payable | 458 | 0 | 9,500 |
Proceeds from the exercise of stock options | 235 | 189 | 42 |
Proceeds from the exercise of preferred stock warrants | 0 | 277 | 0 |
Proceeds from sale of preferred stock | 24,968 | 12,348 | 0 |
Net cash provided by financing activities | 25,661 | 12,814 | 2,542 |
Increase in cash and cash equivalents | 2,270 | (5,441) | 3,852 |
Cash and cash equivalents at beginning of period | 6,685 | 12,126 | 8,274 |
Cash and cash equivalents at end of period | 8,955 | 6,685 | 12,126 |
Supplemental cash flow information | |||
Debt issuance costs | 0 | 0 | 72 |
Cash paid for interest | 1,323 | 1,232 | 1,192 |
Issuance of preferred stock warrants | $ 4 | $ 0 | $ 33 |
Organization
Organization | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Organization, Consolidation and Presentation of Financial Statements [Abstract] | ||
Organization | Organization Description of Business Inspire Medical Systems, Inc. is a medical technology company focused on the development and commercialization of innovative and minimally invasive solutions for patients with obstructive sleep apnea ("OSA"). Our proprietary Inspire system is the first and only FDA-approved neurostimulation technology that provides a safe and effective treatment for moderate to severe obstructive sleep apnea. We have developed a novel, closed-loop solution that continuously monitors a patient's breathing and delivers mild hypoglossal nerve stimulation to maintain an open airway. Inspire therapy received premarket approval ("PMA") from the U.S. Food and Drug Administration ("FDA") in April 2014 and has been commercially available in certain European markets since November 2011. In June 2018, Japan's Ministry of Health, Labour and Welfare approved Inspire therapy to treat moderate to severe OSA, and we will now seek reimbursement coverage in Japan. | 1. Organization Description of Business Inspire Medical Systems, Inc. (the Company) is a medical technology company focused on the development and commercialization of innovative and minimally invasive solutions for patients with obstructive sleep apnea. The Company's proprietary Inspire system is the first and only FDA-approved neurostimulation technology that provides a safe and effective treatment for moderate to severe obstructive sleep apnea. The Company has developed a novel, closed-loop solution that continuously monitors a patient’s breathing and delivers mild hypoglossal nerve stimulation to maintain an open airway. Inspire therapy received premarket approval, or PMA, from the U.S. Food and Drug Administration, or FDA, in April 2014 and has been commercially available in certain European markets since November 2011. |
Summary of Significant Accounti
Summary of Significant Accounting Policies | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Accounting Policies [Abstract] | ||
Summary of Significant Accounting Policies | Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed financial statements have been prepared without audit, pursuant to the rules and regulations of the SEC. The condensed financial statements may not include all disclosures required by U.S. GAAP; however, we believe that the disclosures are adequate to make the information presented not misleading. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and the notes thereto for the fiscal year ended December 31, 2017 included in our audited consolidated financial statements for the year ended December 31, 2017 and the notes thereto for the year ended December 31, 2017 included in our final prospectus that forms a part of our Registration Statement on Form S-1 (File No. 333-224176), filed with the Securities and Exchange Commission ("SEC") pursuant to Rule 424(b)(4) on May 4, 2018 (the "Prospectus"). The condensed balance sheet at December 31, 2017 was derived from the audited financial statements. In the opinion of management, all adjustments, consisting of only normal recurring adjustments that are necessary to present fairly the financial position, results of operations, and cash flows for the interim periods, have been made. The results of operations for the interim periods are not necessarily indicative of the operating results for the full fiscal year or any future periods. Reverse Stock Split In connection with our initial public offering of common stock ("IPO"), our board of directors and stockholders approved a 1-for-6.650 reverse stock split of our common stock. The reverse stock split became effective on April 20, 2018. The par value of the common stock was not adjusted as a result of the reverse stock split. Adjustments corresponding to the reverse stock split were made to the ratio at which the convertible preferred stock will convert into common stock immediately prior to the closing of the IPO. Accordingly, all share and per-share amounts for all periods presented in these financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect the reverse stock split and adjustment of the conversion ratio of the convertible preferred stock. Initial Public Offering On May 7, 2018, we completed our IPO by issuing 7,762,500 shares of common stock, at an offering price of $16.00 per share, for net proceeds of approximately $112.0 million after deducting underwriting discounts and commissions and offering expenses payable by us. In connection with the IPO, our outstanding shares of convertible preferred stock were automatically converted into an aggregate of 12,111,706 shares of common stock, and our outstanding warrants to purchase shares of convertible preferred stock were automatically converted into warrants to purchase up to an aggregate of 100,558 shares of common stock, resulting in the reclassification of the related redeemable convertible preferred stock warrant liability of $0.9 million to additional paid-in capital ("APIC"). Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. We use significant judgment when making estimates related to the allowance for doubtful accounts, inventory reserves and the valuations of our common stock, share-based awards, and certain of our previously outstanding preferred stock warrants. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. JOBS Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act"), we are eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. We have elected to take advantage of the extended transition period for adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. Cash and Cash Equivalents We consider all highly liquid securities, readily convertible to cash, that mature within 90 days or less from the date of purchase to be cash equivalents. The carrying amount reported in the balance sheets for cash is cost, which approximates fair value. Short-Term Investments At September 30, 2018 and December 31, 2017 , our short-term investments consisted of commercial paper, corporate bonds, and U.S. government securities which are classified as available-for-sale and had maturities less than one year. Short-term investments are reported at their estimated fair market value which approximates cost. Any unrealized gains and losses are reported in accumulated other comprehensive loss. We had less than $0.1 million and $0 accumulated other comprehensive loss balance at September 30, 2018 or December 31, 2017 , respectively. Any realized gains and losses are reported net in interest income or interest expense. For the nine months ended September 30, 2018 , we recognized $0.4 million of gains, net. Fair Value of Financial Instruments We measure certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents, short-term investments, and certain of our previously outstanding preferred stock warrants. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Observable inputs, such as quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Other inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs, including interest rate curves, foreign exchange rates, and credit ratings. Level 3—Unobservable inputs that are supported by little or no market activities, which would require us to develop our own assumptions. We use the methods and assumptions described below in determining the fair value of our financial instruments. Money market funds: Fair values of money market funds are based on quoted market prices in active markets. Commercial paper: Short-term, highly liquid investments are included as a Level 2 measurement in the tables below. Corporate bonds: Consists of notes, asset-backed securities and bonds with original maturities of less than one year and various yields. These are included as a Level 2 measurement in the tables below. U.S. government securities: Consists of U.S. Government treasury bills with original maturities of less than one year. These are included as a Level 1 measurement in the table below. The following tables sets forth by level within the fair value hierarchy our assets and liabilities that are reported at fair value as of September 30, 2018 and December 31, 2017 . As required by Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 820, Fair Value Measurement , assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of September 30, 2018 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 14,250 $ 14,250 $ — $ — Commercial paper 10,382 — 10,382 — Total cash equivalents 24,632 14,250 10,382 — Short-term investments: Commercial paper $ 47,631 $ — $ 47,631 $ — Corporate bonds 34,576 — 34,576 — U.S. government securities 11,907 11,907 — — Total short-term investments 94,114 11,907 82,207 — Total assets $ 118,746 $ 26,157 $ 92,589 $ — Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 $ — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 There were no transfers in and out of Level 1 and Level 2 fair value measurements during the periods ended September 30, 2018 and December 31, 2017 . The recurring Level 3 fair value measurements of our preferred stock warrant liabilities used the Black-Scholes option pricing model and value of the respective class of our convertible preferred stock (see Note 8 ), which was unobservable. All other assumptions included in the model are observable Level 1 inputs. The following table provides a reconciliation of the beginning and ending balances of our preferred stock warrant liabilities: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Balance at beginning of period $ — $ 57 $ 157 $ 53 Initial fair value of preferred stock warrants issued — — 103 4 Reclassified to equity — — (855 ) — Change in fair value of preferred stock warrants — — 595 — Balance at end of period $ — $ 57 $ — $ 57 Changes in the fair value of the preferred stock warrant liability were recorded in other expenses on the condensed statements of operations and comprehensive loss. In connection with the closing of the IPO in May 2018, warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock, resulting in the reclassification of the related convertible preferred stock warrant liability to APIC. Concentration of Credit Risk Financial instruments, which potentially subject us to concentrations of credit risk, consist principally of cash equivalents and accounts receivable. We believe that the credit risk in our accounts receivable is mitigated by our credit evaluation process, relatively short collection terms, and dispersion of our customer base. We generally do not require collateral, and losses on accounts receivable have historically been within management's expectations. Our investment policy limits investments to certain types of debt securities issued by the U.S. government and its agencies, corporations with investment-grade credit ratings, or commercial paper and money market funds issued by the highest quality financial and non-financial companies. We place restrictions on maturities and concentration by type and issuer. We are exposed to credit risk in the event of a default by the issuers of these securities to the extent recorded on the balance sheets. However, as of September 30, 2018 and December 31, 2017 , we limited our credit risk associated with cash equivalents by placing investments with banks we believe are highly creditworthy. Allowance for Doubtful Accounts We record an allowance for doubtful accounts for accounts receivable deemed uncollectible. We evaluate the collectability of our accounts receivable based on known collection risks and historical experience. In circumstances where we are aware of a specific customer's inability to meet its financial obligations to us (e.g., bankruptcy filings, substantial downgrading of credit ratings), we record a specific allowance for bad debts against amounts due to reduce the carrying amount of accounts receivable to the amount we reasonably believe will be collected. Inventories Inventories are valued at the lower of cost or net realizable value, computed on a first-in, first out basis. We regularly review inventory quantities on-hand for excess and obsolete inventory and, when circumstances indicate, incur charges to write down inventories to their net realizable value. Our review of inventory for excess and obsolete quantities is based primarily on the estimated forecast of future product demand, product life cycles, including expiration of inventory prior to sale, and introduction of new products. The reserve for excess and obsolete inventory was $0.8 million and $0.5 million as of September 30, 2018 and December 31, 2017 , respectively. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. Impairment of Long-lived Assets Long-lived assets consist primarily of property and equipment and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require that an asset be tested for possible impairment, we compare the undiscounted cash flows expected to be generated by the asset to the carrying amount of the asset. If the carrying amount of the asset is not recoverable on an undiscounted cash flow basis, we determine the fair value of the asset and recognize an impairment loss to the extent the carrying amount of the asset exceeds its fair value. We determine fair value using the income approach based on the present value of expected future cash flows or other appropriate measures of estimated fair value. Our cash flow assumptions consider historical and forecasted revenue and operating costs and other relevant factors. We did not record any impairment charges on long-lived assets during the nine months ended September 30, 2018 and 2017 . Revenue Recognition We recognize revenue when persuasive evidence of an arrangement exists, product shipment has occurred, or there are no further obligations yet to be performed, pricing is fixed or determinable, and collection is reasonably assured. We make reasonable assumptions regarding the future collectability of amounts receivable from customers to determine whether the revenue recognition criteria have been met. Taxes assessed by a governmental authority that are directly imposed on revenue-producing transactions between a seller and a customer are not recorded as revenue. In general, our standard terms and conditions of sale do not allow for product returns. Sales returns have been limited to damaged product and have not been material. We expense shipping and handling costs as incurred and include them in the cost of goods sold. In those cases where shipping and handling costs are billed to customers, we classify the amounts billed as a component of cost of goods sold. Cost of Goods Sold Cost of goods sold consists primarily of manufacturing overhead costs, material costs, and direct labor. Overhead costs include the cost of material procurement, inventory control, facilities, equipment, and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs. Research and Development Research and development expenses consist primarily of product development, clinical and regulatory affairs, consulting services, and other costs associated with products and technologies in development. These expenses include employee compensation, stock-based compensation, supplies, travel, and facility costs. Clinical expenses include clinical trial design, clinical site reimbursement, data management, travel expenses, and the cost of manufacturing products for clinical trials. Common Stock Valuation and Stock-Based Compensation We maintain an equity incentive plan to provide long-term incentives for employees, consultants, and members of the board of directors. The plan allows for the issuance of non-statutory and incentive stock options to employees and non-statutory stock options to consultants and non-employee directors. We recognize equity-based compensation expense for awards of equity instruments to employees and non-employees based on the grant date fair value of those awards in accordance with FASB ASC Topic 718, Stock Compensation ("ASC 718"). ASC 718 requires all equity-based compensation awards to employees and nonemployee directors, including grants of restricted shares and stock options, to be recognized as expense in the statements of operations and comprehensive loss based on their grant date fair values. We estimate the fair value of stock options using the Black-Scholes option pricing model. We use the value of our common stock to determine the fair value of restricted shares. We account for restricted stock and common stock options issued to nonemployees under FASB ASC Topic 505-50, Equity-Based Payments to Non-Employees . As such, the value of such options is periodically remeasured and income or expense is recognized over their vesting terms. Compensation cost related to awards with service-based vesting schedules is recognized using the straight-line method. We determine the fair value of the restricted stock and common stock granted to nonemployees as either the fair value of the consideration received or the fair value of the equity instruments issued. We have not granted any share-based awards to our consultants. The Black-Scholes option pricing model requires the input of certain subjective assumptions, including (i) the expected share price volatility, (ii) the expected term of the award, (iii) the risk-free interest rate and (iv) the expected dividend yield. Due to the lack of a public market for the trading of our common stock and a lack of company-specific historical and implied volatility data, we have based our estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The group of representative companies have characteristics similar to us, including stage of product development and focus on the life science industry. We use the simplified method, which is the average of the final vesting tranche date and the contractual term, to calculate the expected term for options granted to employees as we do not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. For options granted to non-employees, we utilize the contractual term of the arrangement as the basis for the expected term assumption. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. We use an assumed dividend yield of zero as we have never paid dividends and have no current plans to pay any dividends on our common stock. We expense the fair value of our equity-based compensation awards granted to employees on a straight-line basis over the associated service period, which is generally the period in which the related services are received. We measure equity-based compensation awards granted to nonemployees at fair value as the awards vest and recognize the resulting value as compensation expense at each financial reporting period. We account for award forfeitures as they occur. Advertising Expenses We expense the costs of advertising, including promotional expenses, as incurred. Advertising expenses were $2.0 million and $1.4 million during the three months ended September 30, 2018 and 2017 , respectively, and $5.8 million and $3.7 million during the nine months ended September 30, 2018 and 2017 , respectively. Income Taxes We account for income taxes using the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates that will be in effect when the differences are expected to reverse. Valuation allowances against deferred tax assets are established, when necessary, to reduce deferred tax assets to the amounts expected to be realized. As we have historically incurred operating losses, we have recorded a full valuation allowance against our net deferred tax assets, and there is no provision for income taxes. Our policy is to record interest and penalties expense related to uncertain tax positions as other expense in the statements of operations and comprehensive loss. Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on short-term investments classified as available-for-sale, if any. Accumulated other comprehensive loss is presented in the accompanying balance sheets as a component of stockholders' equity, if any. Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because we have reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, stock options and warrants were antidilutive in those periods. Recent Accounting Pronouncements We are an “emerging growth company” as defined by the JOBS Act. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act of 1933, as amended, (the "Securities Act"), for complying with new or revised accounting standards. Accordingly, an emerging growth company can selectively delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this exemption and, as a result, our financial statements may not be comparable to the financial statements of issuers that are required to comply with the effective dates for new or revised accounting standards that are applicable to public companies. Section 107 of the JOBS Act provides that we can elect to opt out of the extended transition period at any time, which election is irrevocable. In May 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers . The new section will replace Section 605, Revenue Recognition , and creates modifications to various other revenue accounting standards for specialized transactions and industries. The section is intended to conform revenue accounting principles with the concurrently issued International Financial Reporting Standards to reconcile previously differing treatment between U.S. practices and those of the rest of the world and to enhance disclosures related to disaggregated revenue information. The updated guidance is effective for interim and annual reporting periods beginning on or after December 15, 2018 for private companies and, therefore, us due to the JOBS Act exemption described above. We have commenced project planning for our implementation, which has included engaging an accounting firm to assist us. We have not yet made a determination on our transition method, nor have we determined whether this standard will have a material impact on our financial statements. We plan to complete our assessment of the impact of this standard during the fourth quarter of 2018. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes ("ASU 2015-17"). ASU 2015-17 is intended to reduce complexity surrounding the presentation of deferred taxes within the balance sheet. Specifically, ASU 2015-17 requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non-current on the balance sheet, effectively eliminating the requirement to allocate deferred taxes between current and non-current amounts. The new guidance does not permit companies to offset deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. This guidance was effective January 1, 2018 and did not significantly impact our financial statements and related disclosures. In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842), which supersedes the existing guidance for lease accounting, Leases (Topic 840). ASU 2016-02 requires lessees to recognize a lease liability and a right-of-use asset for all leases. Lessor accounting remains largely unchanged. The amendments in this ASU are effective for interim and annual periods beginning after December 15, 2019 for private companies; and, therefore, us due to the JOBS Act exemption described above. Early adoption is permitted for all entities. ASU 2016-02 requires a modified retrospective approach for all leases existing at, or entered into after, the date of initial adoption, with an option to elect to use certain transition relief. We plan to further evaluate the anticipated impact of the adoption of this ASU on our financial statements in future periods. In March 2016, the FASB issued No. 2016-9, Improvements to Employee Share-Based Payment Accounting ("ASU 2016-9"), which changes how companies will account for certain aspects of share-based payments to employees. As part of the new guidance, entities will be required to record the impact of income taxes arising from share-based compensation when awards vest or are settled within earnings as part of income tax expense rather than recorded as part of APIC and will eliminate the requirement that excess tax benefits be realized prior to recognition. Additionally, the guidance requires entities to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. Additionally, companies will be required to make an accounting policy election at the time of adoption of the new guidance to either account for forfeitures of share-based awards in a manner similar to today's requirements (i.e., estimating the number of awards expected to be forfeited at the grant date and adjusting the estimate when awards are actually forfeited), or recognizing forfeitures as they occur with no estimate of forfeitures determined at the grant date. Companies will also be able to set a maximum statutory tax rate as it pertains to share-based awards it net settles on behalf of its employees. This will provide companies a greater ability to retain equity-award accounting treatment. Entities will apply the provisions of ASU 2016-9 using a modified retrospective transition approach, with a cumulative-effect adjustment booked to retained earnings as of the beginning of the period of adoption. This guidance was effective for us on January 1, 2018 and did not significantly impact our financial statements and related disclosures. We have reviewed and considered all other recent accounting pronouncements and believe there are none that could potentially have a material impact on our business practices, financial condition, results of operations, or disclosures. | 2. Summary of Significant Accounting Policies Basis of Presentation The financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP). Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its allowance for doubtful accounts, inventory reserves and the valuations of its common stock, share‑based awards, and certain of its outstanding preferred stock warrants. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. JOBS Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act, the Company is eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. The Company has elected to take advantage of the extended transition period for adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. Cash and Cash Equivalents The Company considers all highly liquid securities, readily convertible to cash, that mature within 90 days or less from the date of purchase to be cash equivalents. The carrying amount reported in the balance sheets for cash is cost, which approximates fair value. Short‑term Investments The Company had no short-term investments at December 31, 2016. At December 31, 2017, the Company's short-term investments consisted of commercial paper and corporate bonds which are classified as available-for-sale and had maturities less than one year. Short-term investments are reported at their estimated fair market value which approximates cost at December 31, 2017. Any with unrealized gains and losses are reported in accumulated other comprehensive loss. Fair Value of Financial Instruments The Company measures certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents and certain of its outstanding preferred stock warrants. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market‑based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three‑tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Observable inputs, such as quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Other inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model‑based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market‑based observable inputs, including interest rate curves, foreign exchange rates, and credit ratings. Level 3—Unobservable inputs that are supported by little or no market activities, which would require the Company to develop its own assumptions. The Company uses the methods and assumptions described below in determining the fair value of its financial instruments. Money market funds: Fair values of money market funds are based on quoted market prices in active markets. Commercial paper: Short‑term, highly liquid investments are included as a Level 2 measurement in the tables below. Corporate bonds: Consists of U.S. Government treasury bills, notes, and bonds with original maturities of less than one year and various yields. These are included as a Level 2 measurement in the tables below. The following tables sets forth by level within the fair value hierarchy the Company’s assets and liabilities that are reported at fair value as of December 31, 2016 and 2017. As required by Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 820, Fair Value Measurement , assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of December 31, 2016 Estimated Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ $ $ — $ — Liabilities Preferred stock warrants $ $ — $ — $ Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 There were no transfers in and out of Level 1 and Level 2 fair value measurements during the years ended December 31, 2016 and 2017. The recurring Level 3 fair value measurements of the Company's preferred stock warrant liabilities use the Black-Scholes option pricing model and value of the respective class of the Company's convertible preferred stock (see Note 7), which is unobservable. All other assumptions included in the model are observable Level 1 inputs. The following table provides a reconciliation of the beginning and ending balances of the Company's preferred stock warrant liabilities: Balance as of December 31, 2014 $ Initial fair value of preferred stock warrants issued 33 Change in fair value of preferred stock warrants 12 Balance as of December 31, 2015 248 Change in fair value of preferred stock warrants (195) Balance as of December 31, 2016 53 Initial fair value of preferred stock warrants issued Change in fair value of preferred stock warrants Balance as of December 31, 2017 $ 157 Changes in the fair value of the preferred stock warrant liability are recorded in other expenses on the statements of operations and comprehensive loss. Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentrations of credit risk, consist principally of cash equivalents and accounts receivable. The Company believes that the credit risk in its accounts receivable is mitigated by its credit evaluation process, relatively short collection terms, and dispersion of its customer base. The Company generally does not require collateral, and losses on accounts receivable have historically been within management’s expectations. The Company’s investment policy limits investments to certain types of debt securities issued by the U.S. government and its agencies, corporations with investment‑grade credit ratings, or commercial paper and money market funds issued by the highest quality financial and non‑financial companies. The Company places restrictions on maturities and concentration by type and issuer. The Company is exposed to credit risk in the event of a default by the issuers of these securities to the extent recorded on the balance sheets. However, as of December 31, 2016 and 2017, the Company has limited its credit risk associated with its cash equivalents by placing its investments with banks it believes are highly creditworthy. Allowance for Doubtful Accounts The Company records an allowance for doubtful accounts for accounts receivable deemed uncollectible. The Company evaluates the collectability of its accounts receivable based on known collection risks and historical experience. In circumstances where the Company is aware of a specific customer’s inability to meet its financial obligations to the Company (e.g., bankruptcy filings, substantial downgrading of credit ratings), the Company records a specific allowance for bad debts against amounts due to reduce the carrying amount of accounts receivable to the amount it reasonably believes will be collected. Inventories Inventories are valued at the lower of cost or net realizable value, computed on a first-in, first out basis. The Company regularly reviews inventory quantities on-hand for excess and obsolete inventory and, when circumstances indicate, incurs charges to write down inventories to their net realizable value. The Company's review of inventory for excess and obsolete quantities is based primarily on the estimated forecast of future product demand, product life cycles, including expiration of inventory prior to sale, and introduction of new products. The reserve for excess and obsolete inventory was $191 and $518 as of December 31, 2016 and 2017, respectively. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight‑line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. Impairment of Long‑lived Assets Long‑lived assets consist primarily of property and equipment and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require that an asset be tested for possible impairment, the Company compares the undiscounted cash flows expected to be generated by the asset to the carrying amount of the asset. If the carrying amount of the asset is not recoverable on an undiscounted cash flow basis, the Company determines the fair value of the asset and recognizes an impairment loss to the extent the carrying amount of the asset exceeds its fair value. The Company determines fair value using the income approach based on the present value of expected future cash flows or other appropriate measures of estimated fair value. The Company’s cash flow assumptions consider historical and forecasted revenue and operating costs and other relevant factors. The Company did not record any impairment charges on long‑lived assets during the years ended December 31, 2015, 2016 and 2017. Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, product shipment has occurred, or there are no further obligations yet to be performed, pricing is fixed or determinable, and collection is reasonably assured. The Company makes reasonable assumptions regarding the future collectability of amounts receivable from customers to determine whether the revenue recognition criteria have been met. Taxes assessed by a governmental authority that are directly imposed on revenue‑producing transactions between a seller and a customer are not recorded as revenue. In general, the Company’s standard terms and conditions of sale do not allow for product returns. Sales returns have been limited to damaged product and have not been material. The Company expenses shipping and handling costs as incurred and includes them in the cost of goods sold. In those cases where shipping and handling costs are billed to customers, the Company classifies the amounts billed as a component of cost of goods sold. Cost of Goods Sold Cost of goods sold consists primarily of manufacturing overhead costs, material costs, and direct labor. Overhead costs include the cost of material procurement, inventory control, facilities, equipment, and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs. Research and Development Research and development expenses consist primarily of product development, clinical and regulatory affairs, consulting services, and other costs associated with products and technologies in development. These expenses include employee compensation, stock-based compensation, supplies, travel, and facility costs. Clinical expenses include clinical trial design, clinical site reimbursement, data management, travel expenses, and the cost of manufacturing products for clinical trials. Common Stock Valuation and Stock‑Based Compensation The Company maintains an equity incentive plan to provide long-term incentives for employees, consultants, and members of the board of directors. The plan allows for the issuance of non-statutory and incentive stock options to employees and non-statutory stock options to consultants and non-employee directors. The Company recognizes equity‑based compensation expense for awards of equity instruments to employees and non‑employees based on the grant date fair value of those awards in accordance with FASB ASC Topic 718, Stock Compensation (ASC 718). ASC 718 requires all equity‑based compensation awards to employees and nonemployee directors, including grants of restricted shares and stock options, to be recognized as expense in the statements of operations and comprehensive loss based on their grant date fair values. The Company estimates the fair value of stock options using the Black‑Scholes option pricing model. The Company uses the value of its common stock to determine the fair value of restricted shares. The Company accounts for restricted stock and common stock options issued to nonemployees under FASB ASC Topic 505‑50, Equity‑Based Payments to Non‑Employees (ASC 505‑50). As such, the value of such options is periodically remeasured and income or expense is recognized over their vesting terms. Compensation cost related to awards with service‑based vesting schedules is recognized using the straight‑line method. The Company determines the fair value of the restricted stock and common stock granted to nonemployees as either the fair value of the consideration received or the fair value of the equity instruments issued. The Company has not granted any share‑based awards to its consultants. The Black‑Scholes option pricing model requires the input of certain subjective assumptions, including (i) the expected share price volatility, (ii) the expected term of the award, (iii) the risk‑free interest rate and (iv) the expected dividend yield. Due to the lack of a public market for the trading of the Company’s common stock and a lack of company‑specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The group of representative companies have characteristics similar to the Company, including stage of product development and focus on the life science industry. The Company uses the simplified method, which is the average of the final vesting tranche date and the contractual term, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. For options granted to non‑employees, the Company utilizes the contractual term of the arrangement as the basis for the expected term assumption. The risk‑free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The Company uses an assumed dividend yield of zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock. The Company expenses the fair value of its equity‑based compensation awards granted to employees on a straight‑line basis over the associated service period, which is generally the period in which the related services are received. The Company measures equity‑based compensation awards granted to nonemployees at fair value as the awards vest and recognizes the resulting value as compensation expense at each financial reporting period. The Company accounts for award forfeitures as they occur. Advertising Expenses The Company expenses the costs of advertising, including promotional expenses, as incurred. Advertising expenses were $2.2 million, $3.4 million and $5.5 million during the years ended December 31, 2015, 2016, and 2017, respectively. Income Taxes The Company accounts for income taxes using the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates that will be in effect when the differences are expected to reverse. Valuation allowances against deferred tax assets are established, when necessary, to reduce deferred tax assets to the amounts expected to be realized. As the Company has historically incurred operating losses, the Company has recorded a full valuation allowance against its net deferred tax assets, and there is no provision for income taxes. The Company's policy is to record interest and penalties expense related to uncertain tax positions as other expense in the statements of operations and comprehensive loss. Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on short‑term investments classified as available‑for‑sale, if any. Accumulated other comprehensive loss is presented in the accompanying balance sheets as a component of stockholders’ (deficit) equity. Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because the Company has reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, stock options and warrants were antidilutive in those periods. Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (ASU) No. 2014‑09, Revenue From Contracts With Customers (ASU 2014‑09), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014‑09 will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. In doing so, companies will need to use more judgment and make more estimates than under current guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price, and allocating the transaction price to each separate performance obligation. Under the original pronouncement, ASU 2014‑09 would have been effective for the Company’s annual reporting periods beginning January 1, 2018. In August 2015, the FASB issued ASU No. 2015‑14, which formally defers the effective date of the new revenue standard by one year. As a result, the updated revenue guidance will be effective for the Company’s annual reporting periods beginning January 1, 2019, and early adoption is permitted as of the original effective date contained within the original standard. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that ASU 2014‑09 will have on its financial statements and related disclosures. In July 2015, the FASB issued ASU 2015‑11 Simplifying the Measurement of Inventory , which is intended to narrow down the alternative methods available for valuing inventory. The new guidance does not apply to inventory currently measured using the last‑in‑first‑out or the retail inventory valuation methods. Under the new guidance, inventory valued using other methods, including the first‑in‑first‑out method, must be valued at the lower of cost or net realizable value. This guidance is effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2016. This guidance was effective January 1, 2017 and did not have a material impact on the Company’s financial position, results of operations and cash flows. In November 2015, the FASB issued ASU No. 2015‑17, Balance Sheet Classification of Deferred Taxes (ASU 2015‑17). ASU 2015‑17 is intended to reduce complexity surrounding the presentation of deferred taxes within the balance sheet. Specifically, ASU 2015‑17 requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non‑current on the balance sheet, effectively eliminating the requirement to allocate deferred taxes between current and non‑current amounts. The new guidance does not permit companies to offset deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. ASU 2015‑17 will be effective for the Company’s annual reporting periods beginning January 1, 2018, and can be applied on either a prospective or retrospective basis; early adoption is also permitted. The Company does not expect the ASU 2015‑17 to significantly impact its financial statements and related disclosures. In February 2016, the FASB issued ASU No. 2016‑02, Leases (ASU 2016‑02). ASU 2016‑02 will require entities that lease assets to recognize the rights and obligations associated with those leases on their balance sheets. The guidance will be effective for the Company’s annual reporting period beginning January 1, 2020, with early adoption permitted. The Company is evaluating the impact this standard will have on its financial statements and related disclosures. In March 2016, the FASB issued No. 2016‑09, Improvements to Employee Share‑Based Payment Accounting (ASU 2016‑09), which changes how companies will account for certain aspects of share‑based payments to employees. As part of the new guidance, entities will be required to record the impact of income taxes arising from share‑based compensation when awards vest or are settled within earnings as part of income tax expense rather than recorded as part of additional paid‑in capital (APIC) and will eliminate the requirement that excess tax benefits be realized prior to recognition. Additionally, the guidance requires entities to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. Additionally, companies will be required to make an accounting policy election at the time of adoption of the new guidance to either account for forfeitures of share‑based awards in a manner similar to today’s requirements (i.e., estimating the number of awards expected to be forfeited at the grant date and adjusting the estimate when awards are actually forfeited), or recognizing forfeitures as they occur with no estimate of forfeitures determined at the grant date. Companies will also be able to set a maximum statutory tax rate as it pertains to share‑based awards it net settles on behalf of its employees. This will provide companies a greater ability to retain equity‑award accounting treatment. Entities will apply the provisions of ASU 2016‑09 using a modified retrospective transition approach, with a cumulative‑effect adjustment booked to retained earnings as of the beginning of the period of adoption. The guidance will be effective for the Company’s annual reporting periods beginning January 1, 2018, with early adoption permitted. The Company is evaluating the impact this standard will have on its financial statements and related disclosures. The Company has reviewed and considered all other recent accounting pronouncements and believes there are none that could potentially have a material impact on its business practices, financial condition, results of operations, or disclosures. |
Composition of Certain Financia
Composition of Certain Financial Statement Items | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Composition of Certain Financial Statement Items | ||
Composition of Certain Financial Statement Items | Composition of Certain Financial Statement Items Inventories September 30, 2018 December 31, 2017 Raw materials $ 1,054 $ 1,323 Finished goods 2,021 2,347 Total inventories, net of reserves $ 3,075 $ 3,670 Property and Equipment September 30, 2018 December 31, 2017 Computer equipment and software $ 333 $ 351 Furniture and office equipment 148 137 Manufacturing equipment 857 1,108 Research and development equipment 30 30 Leasehold improvements 185 178 Property and equipment, cost 1,553 1,804 Less: accumulated depreciation and amortization (788 ) (810 ) Property and equipment, net $ 765 $ 994 Depreciation and amortization expense was $0.1 million for both the three months ended September 30, 2018 and 2017 , respectively, and $0.3 million and $0.2 million for the nine months ended September 30, 2018 and 2017 , respectively. Accrued Expenses September 30, 2018 December 31, 2017 Payroll and commissions payable $ 3,619 $ 2,871 Vacation 946 723 Other accrued expenses 397 438 Total accrued expenses $ 4,962 $ 4,032 | 3. Composition of Certain Financial Statement Items Inventories Inventory balances, net of reserves, consist of the following: December 31, 2016 2017 Raw materials $ 738 $ 1,323 Finished goods 2,617 2,347 $ 3,355 $ 3,670 Property and Equipment December 31, 2016 2017 Computer equipment and software $ 75 $ 351 Furniture and office equipment 84 137 Manufacturing equipment 1,329 1,108 Research and development equipment 34 30 Leasehold improvements 26 178 1,548 1,804 Less: accumulated depreciation and amortization (681) (810) $ 867 $ 994 Depreciation and amortization expense was $120, $103 and $285 during the years ended December 31, 2015, 2016 and 2017, respectively. Accrued Expenses December 31, 2016 2017 Payroll and commissions payable $ 1,861 $ 2,871 Vacation 564 723 Other accrued expenses 279 438 $ 2,704 $ 4,032 |
Long-Term Debt
Long-Term Debt | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Long-term Debt, by Current and Noncurrent [Abstract] | ||
Long-Term Debt | Long-Term Debt Credit Facility In August 2015, we entered into a loan and security agreement, which provided for a term A loan facility in the amount of $15.5 million , the proceeds of which were used to refinance the $12.0 million of borrowings outstanding under our original credit facility, and a term B loan facility in an amount between $3.5 million and $10.0 million , subject to our achievement of certain revenue milestones. Amounts outstanding under the credit facility bore interest at a fixed rate of 7.95% per annum. In February 2017, we amended the loan and security agreement. Under the loan and security agreement, as amended, and subject to the limitation noted below, amounts outstanding under the credit facility bear interest at a floating interest rate equal to the greater of 7.95% or LIBOR plus 6.9% per annum. Upon execution of the amendment, we borrowed an additional $1.0 million under the term A loan portion of the credit facility, receiving net proceeds of $0.5 million , net of expenses, for a total of $16.5 million outstanding under the credit facility and reduced borrowings available under the term B loan facility to $9.0 million . In connection with the execution of the amendment to the loan and security agreement, we issued 29,197 ten -year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. On February 7, 2018, we borrowed an additional $8.0 million under the term B loan facility portion of the credit facility. After receipt of the $8.0 million , we had a total of $24.5 million outstanding under the credit facility, which bears interest at a floating interest rate equal to the greater of 7.95% or LIBOR plus 6.9% per annum. All amounts borrowed under the credit facility are interest-only through March 1, 2019, after which monthly payments of principal and interest are due through March 1, 2022; provided that the interest-only period will be extended to March 1, 2020 if we have revenue, measured on a trailing 12 -month basis as of December 31, 2018, of at least $25.0 million , which was met during the nine months ended September 30, 2018, and, therefore, the interest-only period is extended to March 1, 2020. In connection with this borrowing, we issued 233,577 ten -year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. In addition to the principal and interest payments, under the credit facility, we are required to pay a final payment fee of 5.0% on all amounts outstanding (or 5.5% if the interest-only period has been extended to March 1, 2020), which is being accreted using the effective interest rate method over the term of the loan and security agreement and shall be due at the earlier of maturity or prepayment. Because the interest-only period has been extended, the final payment fee will be 5.5%. If we repay all the amounts borrowed under the term A loan facility on or prior to maturity, we will also be required to pay a prepayment fee equal to 1.5% if such borrowings are prepaid after February 24, 2018 but prior to February 24, 2019, and 1.00% if such borrowings are prepaid on or after February 24, 2019. Borrowings under the term B loan facility are prepayable at our option in whole, but not in part, together with all accrued and unpaid interest thereon and, if not previously made, the Final Payment, subject to a prepayment fee of 2.5% if the such borrowings are prepaid prior to February 7, 2019, 1.5% if such borrowings are prepaid on or after February 7, 2019 but prior to February 7, 2020 and 1.00% if such borrowings are on or after February 7, 2020. The credit facility includes affirmative and restrictive covenants and events of default, including the following events of default: payment defaults, breaches of covenants, judgment defaults, cross defaults to certain other contracts, certain events with respect to governmental approvals if such events could cause a material adverse change, a material impairment in the perfection or priority of the lender's security interest or in the value of the collateral, a material adverse change in the business, operations, or condition of us or any of our subsidiaries, and a material impairment of the prospect of repayment of the loans. Upon the occurrence of an event of default, a default increase in the interest rate of an additional 5.00% could be applied to the outstanding loan balance and the lender could declare all outstanding obligations immediately due and payable and take such other actions as set forth in the loan and security agreement. Our obligations under the credit facility are secured by a first priority security interest in substantially all of our assets, other than our intellectual property. There are no financial covenants contained in the loan and security agreement. We were in compliance with the affirmative and restrictive covenants as of September 30, 2018 . We paid debt issuance costs of $0.1 million in connection with our entry into the loan and security agreement in August 2015. The costs are being amortized over the term of the loan using the effective interest rate method. We also issued preferred stock warrants in connection with our borrowings under our credit facilities (see Note 8 ). Expected future principal payments for the credit facility are as follows: Year ending December 31 : 2018 (remaining) $ — 2019 — 2020 10,208 2021 12,250 2022 2,042 Total expected future principal payments $ 24,500 | 4. Long‑Term Debt Credit Facility In August 2015, the Company entered into a loan and security agreement, which provided for a term A loan facility in the amount of $15.5 million, the proceeds of which were used to refinance the $12.0 million of borrowings outstanding under the Company's original credit facility, and a term B loan facility in an amount between $3.5 million and $10.0 million, subject to the Company's achievement of certain revenue milestones. Amounts outstanding under the credit facility bore interest at a fixed rate of 7.95% per annum. The Company had $15.5 million outstanding under the credit facility as of December 31, 2015. In February 2017, the Company amended the loan and security agreement. Under the loan and security agreement, as amended, and subject to the limitation noted below, amounts outstanding under the credit facility bear interest at a floating interest rate equal to the greater of 7.95% or LIBOR plus 6.9% per annum. Upon execution of the amendment, the Company borrowed an additional $1.0 million under the term A loan portion of the credit facility, receiving net proceeds of $0.5 million, net of expenses, for a total of $16.5 million outstanding under the credit facility and reduced borrowings available under the term B loan facility to $9.0 million.All amounts borrowed under the credit facility are interest-only through March 1, 2019, after which the Company will make monthly payments of principal and interest through February 2022; provided that the interest-only period will be extended to March 1, 2020 if the Company has revenue, measured on a trailing 12-month basis as of December 31, 2018, of at least $25.0 million. In connection with the execution of the amendment to the loan and security agreement, the Company issued 29,197 ten-year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. In addition to the principal and interest payments, under the credit facility, the Company is required to pay a final payment fee of 5.0% on all amounts outstanding, which is being accreted using the effective interest rate method over the term of the loan and security agreement and shall be due at the earlier of maturity or prepayment. If the Company repays all the amounts borrowed under the term A loan facility on or prior to maturity, the Company will also be required to pay a prepayment fee equal to 2.5% if such borrowings are prepaid prior to February 24, 2018, 1.5% if such borrowings are prepaid on or after February 24, 2018 but prior to February 24, 2019, and 1.00% if such borrowings are prepaid on or after February 24, 2019. Borrowings under the term B loan facility are prepayable at the Company's option in whole, but not in part, together with all accrued and unpaid interest thereon and, if not previously made, the Final Payment, subject to a prepayment fee of 2.5% if the such borrowings are prepaid prior to February 7, 2019, 1.5% if such borrowings are prepaid on or after February 7, 2019 but prior to February 7, 2020 and 1.00% if such borrowings are on or after February 7, 2020. The credit facility includes affirmative and restrictive covenants and events of default, including the following events of default: payment defaults, breaches of covenants, judgment defaults, cross defaults to certain other contracts, certain events with respect to governmental approvals if such events could cause a material adverse change, a material impairment in the perfection or priority of the lender’s security interest or in the value of the collateral, a material adverse change in the business, operations, or condition of the Company or any of its subsidiaries, and a material impairment of the prospect of repayment of the loans. Upon the occurrence of an event of default, a default increase in the interest rate of an additional 5.00% could be applied to the outstanding loan balance and the lender could declare all outstanding obligations immediately due and payable and take such other actions as set forth in the loan and security agreement. The Company's obligations under the credit facility are secured by a first priority security interest in substantially all of its assets, other than its intellectual property. There are no financial covenants contained in the loan and security agreement. The Company was in compliance with the affirmative and restrictive covenants as of December 31, 2016 and 2017. The Company paid debt issuance costs of $72 in connection with its entry into the loan and security agreement in August 2015. The costs are being amortized over the term of the loan using the effective interest rate method. The Company also issued preferred stock warrants in connection with its borrowings under its credit facilities (see Note 7). Expected future principal payments for the credit facility are as follows: Year ending December 31: 2018 $ — 2019 4,583 2020 5,500 2021 5,500 2022 917 $ 16,500 |
Commitments
Commitments | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Commitments and Contingencies Disclosure [Abstract] | ||
Commitments | Commitments Operating Lease We rent office space under an operating lease that expires on March 31, 2019. The lease allows us to terminate the lease any time after March 31, 2017 without a penalty. In September 2018, we entered into a non-cancelable operating lease agreement to sublease approximately 44,000 square feet of office space for our corporate headquarters, which lease is scheduled to commence January 15, 2019 and expire November 30, 2020. Future minimum annual operating lease payments are as follows: Year ending December 31 : 2018 (remaining) $ 48 2019 1,043 2020 952 Total future operating lease payments $ 2,043 Rent expense was less than $0.1 million for both the three months ended September 30, 2018 and 2017 , and $0.1 million for both the nine months ended September 30, 2018 and 2017 . Purchase Commitments As of September 30, 2018 and December 31, 2017 , we had commitments to suppliers for inventory purchases totaling $16.2 million and $9.0 million , respectively, of which less than $0.1 million and $0.4 million , respectively, was committed to Medtronic, a related party. | 5. Commitments Operating Lease The Company rents office space under an operating lease that expires on March 31, 2019. The lease allows the Company to terminate the lease any time after March 31, 2017 without a penalty. Future minimum annual operating lease payments are as follows: Years ending December 31: 2018 $ 190 2019 48 Total $ 238 Rent expense was $123, $127 and $184 during the years ended December 31, 2015, 2016 and 2017, respectively. Purchase Commitments As of December 31, 2016, and 2017, the Company had commitments to suppliers for inventory purchases totaling $6.1 million and $9.0 million, respectively, of which $0.6 million and $0.4 million, respectively, was committed to Medtronic, a related party. |
Employee Retirement Plan
Employee Retirement Plan | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Retirement Benefits [Abstract] | ||
Employee Retirement Plan | Employee Retirement Plan We sponsor an employee retirement plan covering all of our full-time employees. The plan allows for eligible employees to defer a portion of their eligible compensation up to the maximum allowed by IRS Regulations. We may elect to make a voluntary contribution to the plan. We have not made contributions since inception. | 6. Employee Retirement Plan The Company sponsors an employee retirement plan covering all full- time employees of the Company. The plan allows for eligible employees to defer a portion of their eligible compensation up to the maximum allowed by IRS Regulations. The Company may elect to make a voluntary contribution to the plan. The Company did not make contributions for the years ended December 31, 2015, 2016 and 2017. |
Stockholders' Equity
Stockholders' Equity | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Stockholders' Equity Note [Abstract] | ||
Stockholders' Equity | Stockholders' Equity Authorized Shares As of December 31, 2017, we had authorized 186,894,620 shares of stock, of which 110,000,000 shares were designated as common stock and 76,894,620 shares were designated as Series A, B, C, D, E, and F preferred stock. All stock had a par value of $0.001 per share. As of September 30, 2018 , we had authorized 210,000,000 shares of stock, of which 200,000,000 shares are designated as common stock and 10,000,000 shares are designated as preferred stock. All stock has a par value of $0.001 per share. Preferred Stock A summary of preferred stock and its terms as of December 31, 2017, is as follows: Series Shares Authorized Shares Issued and Outstanding Carrying Value Liquidation Preference per Share 8% Dividend per Share Conversion Price per Share A 5,375,507 5,375,507 $ 5,037 $ 1.00 $ 0.08 $ 6.65 B 8,706,909 8,706,909 15,913 1.84 0.15 9.91 C 14,091,589 13,829,906 14,949 1.07 0.09 7.12 D 5,683,292 5,683,292 6,043 1.07 0.09 7.12 E 15,373,091 15,267,175 39,848 2.62 0.21 15.16 F 27,664,232 27,372,261 37,316 1.37 0.11 9.11 Total 76,894,620 76,235,050 $ 119,106 In connection with the IPO in May 2018, the 76,235,050 shares of convertible preferred stock were converted into 12,111,706 shares of common stock, resulting in the reclassification of the related convertible preferred stock of $119.1 million to common stock and APIC. As of September 30, 2018 , no preferred stock had been issued. The dividend per share on the convertible preferred stock was only payable when and if declared by the Board of Directors. Preferred Stock Warrants and Common Stock Warrants As of December 31, 2017, we had warrants outstanding to purchase 396,795 shares of various series of our preferred stock. The warrants had been issued in connection with our various credit facilities and issuances of promissory notes. The original fair value of the warrants was determined using the Black-Scholes option pricing model. In connection with the borrowing completed in February 2018 (see Note 5 ), we issued 233,577 ten -year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. Based on the Black-Scholes option pricing model, the value of each warrant was determined to be $0.44 , for a total value of $0.1 million at the date of issuance and was fully expensed during the three months ended March 31, 2018. The preferred stock warrants issued in connection with the execution of the original credit facility and its subsequent amendments required re-measurement of the value of the preferred stock warrants each period, with changes in fair value recognized within other expenses on the statements of operations and comprehensive loss. The fair value of the preferred stock warrants was determined using the Black-Scholes option pricing model. As of May 7, 2018, the date of the closing of our IPO, the following preferred stock warrants issued under the original credit facility and subsequent amendments were outstanding and exercisable: Issuance Expiration Series Exercise Price Warrants Outstanding at May 7, 2018 Initial Value Fair Value at May 7, 2018 February 8, 2018 February 8, 2028 F $ 1.37 233,577 $ 103 $ 320 February 24, 2017 February 24, 2027 F 1.37 29,197 4 40 August 7, 2015 August 7, 2025 E 2.62 29,580 33 41 June 27, 2014 June 27, 2024 E 2.62 76,334 85 174 August 5, 2013 August 5, 2023 C 1.07 74,768 39 80 November 16, 2012 November 16, 2022 C 1.07 186,916 96 200 Total 630,372 $ 855 In connection with the closing of the IPO in May 2018, the warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock, resulting in the reclassification of the related convertible preferred stock warrant liability of $0.9 million to APIC during the three months ended June 30, 2018. Upon the closing of the IPO, the warrants to purchase 630,372 shares of preferred stock at a weighted average exercise price of $1.46 per share became exercisable to purchase 100,558 shares of common stock at weighted average exercise price of $9.38 per share. Warrants for 19,674 shares were exercised through a cashless exercise on September 10, 2018 , resulting in the issuance of a net 17,050 shares of our common stock. As of December 31, 2017, the following preferred stock warrants issued under the original credit facility and subsequent amendments were outstanding and exercisable: Issuance Expiration Series Exercise Price Warrants Outstanding at December 31, 2017 Initial Value Fair Value at December 31, 2017 February 24, 2017 February 24, 2027 F $ 1.37 29,197 $ 4 $ 13 August 7, 2015 August 7, 2025 E 2.62 29,580 33 8 June 27, 2014 June 27, 2024 E 2.62 76,334 85 21 August 5, 2013 August 5, 2023 C 1.07 74,768 39 33 November 16, 2012 November 16, 2022 C 1.07 186,916 96 82 Total 396,795 $ 157 The warrants issued on August 7, 2015 to purchase Series E preferred stock were subject to the conversion price of the underlying preferred stock. The warrants to purchase 29,580 shares of Series E preferred stock at $2.62 per share has been adjusted to purchase 56,569 shares of Series F preferred stock at $1.37 per share due to the dilutive issuance of the Series F preferred stock. | 7. Stockholders’ (Deficit) Equity Authorized Shares The Company has authorized 186,894,620 shares of stock, of which 110,000,000 shares are designated as common stock and 76,894,620 shares are designated as Series A, B, C, D, E, and F preferred stock. All stock has a par value of $0.001. Preferred Stock A summary of the Company’s preferred stock as of December 31, 2016 and 2017, is as follows: 2016 Shares Shares Issued and Carrying Series Authorized Outstanding Value A 5,375,507 5,375,507 $ 5,037 B 8,706,909 8,706,909 15,913 C 14,091,589 13,829,906 14,949 D 5,683,292 5,683,292 6,043 E 15,373,091 15,267,175 39,848 F 9,124,084 9,124,084 12,348 58,354,472 57,986,873 $ 94,138 2017 Shares Shares Issued and Carrying Series Authorized Outstanding Value A 5,375,507 5,375,507 $ 5,037 B 8,706,909 8,706,909 15,913 C 14,091,589 13,829,906 14,949 D 5,683,292 5,683,292 6,043 E 15,373,091 15,267,175 39,848 F 27,664,232 27,372,261 37,316 76,894,620 76,235,050 $ 119,106 A summary of the Company’s convertible preferred stock terms is as follows: Liquidation 8% Conversion Preference Dividend Price per Series per Share per Share Share A $ $ $ B C D E F The dividend per share on the convertible preferred stock is only payable when, as and if declared by the Board of Directors. The Company has issued 5,375,507 shares of Preferred Stock, Series A, with an original issue price of $1.00 per share. Each share of Series A Preferred Stock may be converted into 0.1504 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series A Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series A Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. The Company has issued 8,706,909 shares of Preferred Stock, Series B, with an original issue price of $1.84 per share. Each share of Series B Preferred Stock may be converted into 0.1855 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Ownership of Series B Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock. Each share of Series B Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. The Company has issued 13,829,906 shares of Preferred Stock, Series C, with an original issue price of $1.07 per share. Each share of Series C Preferred Stock may be converted into 0.1504 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series C Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series C Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. The Company has issued 5,683,292 shares of Preferred Stock, Series D, with an original issue price of $1.07 per share. Each share of Series D Preferred Stock may be converted into 0.1504 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series D Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series D Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. In March 2014, the Company raised $39.8 million, net of stock issuance costs, through the issuance of 15,267,175 shares of Series E Preferred Stock, with an original issue price of $2.62 per share. Each share of Series E Preferred Stock may be converted into 0.1728 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series E Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series E Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. In October 2016, the Company raised $12.3 million, net of stock issuance costs, through the issuance of 9,124,084 shares of Series F Preferred Stock, with an original issue price of $1.37 per share (Tranche 1). In February 2017, the Company raised $25.0 million, net of stock issuance costs, through the issuance of 18,248,177 shares of Series F Preferred Stock, with an original issue price of $1.37 per share (Tranche 2). Each share of Series F Preferred Stock may be converted into 0.1504 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series F Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series F Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. Upon a liquidation, dissolution, or winding up of the Company, the holders of the Series F Preferred Stock shall be entitled to receive prior and in preference to any distribution of any of the assets of the Company to holders of Series A Preferred, Series B Preferred, Series C Preferred, Series D Preferred, Series E Preferred and common stock. If, upon a liquidation, the assets to be distributed to the holders of the Series F Preferred are insufficient to permit the payment to such holders of the full amount payable, then the entire assets of the Company legally available for distribution shall be distributed pro rata to the holders of the Series F Preferred Stock in proportion to the full preferential amounts which each such holder would otherwise be entitled to receive. Preferred Stock Warrants In connection with certain convertible promissory notes issued by the Company during 2011 and 2012 and subsequently paid, the Company issued 278,506 five‑year warrants to purchase Series C preferred shares of stock at an exercise price of $1.07 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $0.34, for a total value of $94, and was fully expensed during the year ended December 31, 2012. As of December 31, 2015, the Company had a total of 258,880 outstanding warrants. In 2016, a total of 258,880 Series C preferred shares were issued upon exercise of the entire remaining warrants for proceeds of $277. In connection with the execution of the Company’s original credit facility entered into during 2012, the Company issued 186,916 ten‑year warrants to purchase Series C preferred shares of stock at an exercise price of $1.07 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $0.515, for a total value of $96 at the date of issuance and was fully expensed during the year ended December 31, 2012. In connection with the added borrowings drawn upon the Company’s original credit facility in 2013, the Company issued 74,768 ten‑year warrants to purchase Series C preferred shares of stock at an exercise price of $1.07 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $0.525, for a total value of $39 at the date of issuance and was fully expensed during the year ended December 31, 2013. In connection with the execution of the Company’s amended credit facility completed in June 2014, the Company also issued 76,334 ten‑year warrants to purchase Series E preferred shares of stock at an exercise price of $2.62 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $1.11, for a total value of $85 at the date of issuance and was fully expensed during the year ended December 31, 2014. In connection with the execution of the Company’s current credit facility completed in August 2015 (see Note 4), the Company issued 29,580 ten‑year warrants to purchase Series E preferred shares of stock at an exercise price of $2.62 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $1.13, for a total value of $33 at the date of issuance and was fully expensed during the year ended December 31, 2015. In connection with the execution of the amendment to the Company’s current credit facility completed in February 2017 (see Note 4), the Company issued 29,197 ten‑year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $0.13, for a total value of $4 at the date of issuance and was fully expensed during the year ended December 31, 2017. The preferred stock warrants issued in connection with the execution of the original credit facility and its subsequent amendments require re-measurement of the value of the preferred stock warrants each period, with changes in fair value recognized within other expenses on the statements of operations and comprehensive loss. The fair value of the preferred stock warrants was determined using the Black-Scholes option pricing model. As of December 31, 2016 and 2017, the following preferred stock warrants issued under the Company’s original credit facility and subsequent amendments were outstanding and exercisable: Warrants Fair Outstanding at Value at Dates Exercise December 31, Initial December 31, Issuance Expiration Series Price 2016 Value 2016 August 7, 2015 August 7, 2025 E $ 2.62 29,580 $ 33 $ 4 June 27, 2014 June 27, 2024 E 2.62 76,334 85 10 August 5, 2013 August 5, 2023 C 1.07 74,768 39 11 November 16, 2012 November 16, 2022 C 1.07 186,916 96 28 367,598 $ 53 Warrants Fair Outstanding at Value at Dates Exercise December 31, Initial December 31, Issuance Expiration Series Price 2017 Value 2017 February 24, 2017 February 24, 2027 F $ 1.37 29,197 $ 4 $ 13 August 7, 2015 August 7, 2025 E 2.62 29,580 33 8 June 27, 2014 June 27, 2024 E 2.62 76,334 85 21 August 5, 2013 August 5, 2023 C 1.07 74,768 39 33 November 16, 2012 November 16, 2022 C 1.07 186,916 96 82 396,795 $ 157 The warrants issued on August 7, 2015 to purchase Series E preferred stock are subject to the conversion price of the underlying preferred stock. The warrants to purchase 29,580 shares of Series E preferred stock at $2.62 per share has been adjusted to purchase 56,569 shares of Series F preferred stock at $1.37 per share due to the dilutive issuance of the Series F preferred stock. |
Stock Options
Stock Options | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | ||
Stock Options | Stock Options We adopted the 2007 Stock Incentive Plan (the "2007 Plan") in November 2007, which terminated in accordance with its terms on November 28, 2017; however, the outstanding stock options may continue to be exercised in accordance with their terms. Immediately following the termination of the 2007 Plan, we adopted the 2017 Stock Incentive Plan (the "2017 Plan"), which contains substantially similar terms and conditions as the 2007 Plan. Upon the IPO, no further grants were made under the 2017 Plan and we adopted the 2018 Stock Incentive Plan (the "2018 Plan"). The purpose of the 2018 Plan is to promote the interest of our company and our stockholders by aiding in attracting and retaining employees, officers, consultants, independent contractors, and directors capable of assuring the future success our business and to afford such persons an opportunity to acquire a proprietary interest our company. The Board may amend, alter, suspend, discontinue, or terminate the 2018 Plan at any time with the approval of our stockholders. As of September 30, 2018 , there were 1,386,809 shares reserved for issuance under the 2018 Plan, of which 1,036,392 shares were available for issuance. Prior to the IPO, the exercise price of stock options represented fair value of the common stock at the time of issuance and was determined by the Board of Directors. Post-IPO, options are granted at the exercise price, which is equal to the closing price of our stock on the date of grant. The options granted during the nine months ended September 30, 2018 contain fixed exercise prices ranging from $2.80 to $54.99 per share with varying expiration and exercise dates and have a weighted average exercise price of $15.04 per share. The stock options granted to employees include a four-year service period and 25% vest after the first year of service and with the remainder vesting pro rata over the next 36 months of service. The stock options granted to the Board of Directors include a one-year service period and all shares vest after the one year of service. The stock options have a contractual life of ten years . A summary of stock option activity and related information is as follows: Options Weighted Average Exercise Price Weighted average remaining contractual term (years) Aggregate intrinsic value (in thousands) Outstanding at December 31, 2017 2,071,616 $ 1.47 5.9 Granted 385,056 $ 15.04 Exercised (227,114 ) $ 1.90 Forfeited (31,428 ) $ 1.05 Outstanding at September 30, 2018 2,198,130 $ 3.80 6.8 $ 84,136 Exercisable at September 30, 2018 1,307,821 $ 1.58 5.4 $ 52,975 Total stock-based compensation recognized, before taxes, during the three and nine months ended September 30, 2018 and 2017 , is as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 General and administrative $ 326 $ 41 $ 592 $ 89 Sales and marketing 41 30 88 73 Research and development 5 10 16 27 Total stock-based compensation $ 372 $ 81 $ 696 $ 189 As of September 30, 2018 , the amount of unearned stock-based compensation currently estimated to be expensed from now through the year 2022 related to unvested employee and non-employee director share-based awards is $2.4 million and the weighted average period over which the unearned stock-based compensation is expected to be recognized is 2.6 years. If there are any modifications or cancellations of the underlying unvested securities, we may be required to accelerate, increase, or cancel any remaining unearned stock compensation expense. Future stock-based compensation expense and unearned stock-based compensation will increase to the extent that we grant additional share-based awards. We estimate the fair value of share-based awards on the date of grant using the Black-Scholes option pricing model using the fair market value of our common stock on the date of grant and a number of other complex and subjective assumptions. These assumptions include, but are not limited to, estimates regarding the expected term of our outstanding awards, estimates of the stock volatility over a duration that approximates the expected life of our outstanding awards, estimates of the risk-free rate, and estimates of expected dividend rates. Due to our limited amount of historical exercise, forfeiture, and expiration activity, we have opted to use the "simplified method" for estimating the expected term of options, whereby the expected term equals the arithmetic average of the vesting terms and the original contractual term of the option. We will continue to analyze our expected term assumption as more historical data becomes available. Due to our limited operating history and a lack of company specific historical and implied volatility data, we have based our estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. When selecting these public companies on which we have based our expected stock price volatility, we generally selected companies with comparable characteristics to it, including enterprise value, stages of clinical development, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. The historical volatility data was computed using the daily closing prices for the selected companies' shares over historical periods that approximate calculated expected term of our share-based awards. We will continue to analyze the historical stock price volatility assumption as more historical data for our common stock becomes available. The risk-free rate assumption is based on the U.S. Treasury instruments with maturities similar to the expected term of our stock options. The expected dividend assumption is based on our history of not paying dividends and our expectation that we will not declare dividends for the foreseeable future. The amount of stock-based compensation expense recognized is based on awards ultimately expected to vest. The amount of expense recognized has been reduced by actual forfeitures as they occur. The fair value of options granted to employees and non-employee directors during the nine months ended September 30, 2018 and 2017 was estimated as of the grant date using the Black-Scholes option pricing model using the following assumptions: Nine Months Ended September 30, 2018 2017 Expected life (years) 5.50 - 6.25 5.75 - 6.25 Expected volatility 37.5 - 49.8% 39.9 - 41.5% Risk-free interest rate 2.38 - 3.01% 1.88 - 2.32% Dividend yield 0.0% 0.0% Weighted average fair value $7.43 $0.40 | 8. Stock Options The Company adopted the 2007 Stock Incentive Plan (the Plan) in November 2007. The purpose of the Plan is to promote the interest of the Company and its stockholders by aiding the Company in attracting and retaining employees, officers, consultants, independent contractors, and directors capable of assuring the future success of the Company’s business and to afford such persons an opportunity to acquire a proprietary interest in the Company. The Board may amend, alter, suspend, discontinue, or terminate the Plan at any time with the approval of the stockholders of the Company. As of December 31, 2017, the number of shares reserved for issuance under the plan is 2,945,384 shares . The exercise price of stock options represent fair value of the common stock at the time of issuance and is determined by the Board of Directors. The options granted contain fixed exercise prices ranging from $0.94 to $6.65 per share with varying expiration and exercise dates. The stock options granted by the Company to employees during 2015, 2016 and 2017 have a weighted average exercise price of $2.07, $1.65 and $0.94, respectively. The stock options granted include a four year service period and 25% vest after the first year of service and then pro rata over the next 36 months of service. The stock options have a contractual life of ten years. A summary of the Company’s stock option activity and related information is as follows: Weighted Average Options Exercise Price Outstanding at December 31, 2014 1,534,672 $ 1.77 Granted 49,235 2.07 Exercised (21,545) 1.96 Forfeited (21,199) 1.15 Outstanding at December 31, 2015 1,541,163 1.77 Granted 120,277 1.65 Exercised (109,079) 1.74 Forfeited (54,850) 1.87 Outstanding at December 31, 2016 1,497,511 1.76 Granted 721,763 0.94 Exercised (127,122) 1.85 Forfeited (20,536) 1.88 Outstanding at December 31, 2017 2,071,616 1.47 Exercisable at December 31, 2017 1,236,255 1.75 At December 31, 2015, the Company had 1,541,163 common stock options outstanding, with an average remaining contractual life of 6.6 years at a weighted average exercise price of $1.77 per share. At December 31, 2016, the Company had 1,497,511 common stock options outstanding, with an average remaining contractual life of 5.8 years at a weighted average exercise price of $1.76 per share. At December 31, 2017, the Company had 2,071,616 common stock options outstanding, with an average remaining contractual life of 5.9 years at a weighted average exercise price of $1.47 per share. Total stock compensation recognized, before taxes, during the years ended December 31, 2015, 2016 and 2017, is as follows: Year ended December 31 2015 2016 2017 General and administrative $ 147 $ 108 $ 116 Sales and marketing 99 90 84 Research and development 59 50 43 $ 305 $ 248 $ 243 As of December 31, 2017, the amount of unearned stock compensation currently estimated to be expensed from now through the year 2021 related to unvested employee and non-employee director share-based awards is $318 and the weighted average period over which the unearned stock compensation is expected to be recognized is 3 years. If there are any modifications or cancellations of the underlying unvested securities, the Company may be required to accelerate, increase, or cancel any remaining unearned stock compensation expense. Future stock compensation expense and unearned stock compensation will increase to the extent that the Company grants additional share-based awards. The Company estimates the fair value of share-based awards on the date of grant using the Black- Scholes option pricing model using the fair market value of the Company’s common stock on the date of grant and a number of other complex and subjective assumptions. These assumptions include, but are not limited to, estimates regarding the expected term of the Company’s outstanding awards, estimates of the stock volatility over a duration that approximates the expected life of the Company’s outstanding awards, estimates of the risk- free rate, and estimates of expected dividend rates. Due to the Company’s limited amount of historical exercise, forfeiture, and expiration activity, the Company has opted to use the “simplified method” for estimating the expected term of options, whereby the expected term equals the arithmetic average of the vesting terms and the original contractual term of the option. The Company will continue to analyze its expected term assumption as more historical data becomes available. Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. When selecting these public companies on which it has based its expected stock price volatility, the Company generally selected companies with comparable characteristics to it, including enterprise value, stages of clinical development, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock- based awards. The historical volatility data was computed using the daily closing prices for the selected companies’ shares over historical periods that approximate calculated expected term of the Company’s share- based awards. The Company will continue to analyze the historical stock price volatility assumption as more historical data for the Company’s common stock becomes available. The risk- free rate assumption is based on the U.S. Treasury instruments with maturities similar to the expected term of the Company’s stock options. The expected dividend assumption is based on the Company’s history of not paying dividends and its expectation that it will not declare dividends for the foreseeable future. The amount of stock compensation expense recognized is based on awards ultimately expected to vest. Due to the Company’s limited forfeiture activity and its vesting terms, the amount of expense recognized by the Company has been reduced by actual forfeitures as they occur. The Company will continue to analyze its historical forfeitures as more historical data becomes available. The fair value of options granted to employees or non- employee directors during the years ended December 31, 2015, 2016 and 2017 was estimated as of the grant date using the Black-Scholes option pricing model, assuming the weighted average assumptions listed in the following table: Year ended December 31, 2015 2016 2017 Expected life (years) Expected volatility % % % Risk-free interest rate 1.65 - 2.14 % 1.27 - 2.25 % 1.88 - 2.32 % Dividend yield 0.0 % 0.0 % 0.0 % Weighted average fair value $ 0.86 $ 0.47 $ 0.40 |
Related-Party Transactions
Related-Party Transactions | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Related Party Transactions [Abstract] | ||
Related-Party Transactions | Related-Party Transactions Board of Directors' Appointment We are party to various agreements and contracts with Medtronic, one of our stockholders. Under these agreements and contracts, Medtronic was allowed to name one person to be a member of our Board of Directors. In connection with the Series F Preferred Stock purchase agreement in 2016, Medtronic agreed to move from one voting member of our Board of Directors to two non-voting members. This right terminated in connection with the completion of our IPO. Supply Agreement We contract with Medtronic to supply all of our commercial and clinical requirements of certain components used to manufacture the Inspire system. The current Supply Agreement expired on June 5, 2017 but was extended to allow Medtronic to complete a final build of the pressure sensor used in our original pressure sensing lead, which was completed in 2018. Upon a change of control event whereby we are owned or controlled by a competitor of Medtronic, Medtronic would have the right to terminate the Supply Agreement, provided that, upon any such termination we would be entitled to exercise a one -time buy right of inventory using current product pricing and upon terms to be agreed upon in the definitive agreements. We purchased inventory at arms-length with Medtronic, a related party, of $0.3 million and $0.8 million for the nine months ended September 30, 2018 and 2017 , respectively. Right-of-First-Offer of the Company Under a Right-of-First-Offer with Medtronic that expired on May 16, 2017, had we decided to initiate a possible sale of our company prior to the expiration date, we would have been required to negotiate exclusively with Medtronic for such transaction for a period of 90 days prior to negotiating with a third party. | 9. Board of Directors’ Appointment The Company has entered into various agreements and contracts with Medtronic, one of the Company’s stockholders. Under these various agreements and contracts, Medtronic is allowed to name one person to be a member of the Company’s Board of Directors. In connection with the Series F Preferred Stock purchase agreement in 2016, Medtronic agreed to move from one voting member of the Company's Board of Directors to two non‑voting members. Supply Agreement The Company contracts with Medtronic to supply all of the Company’s commercial and clinical requirements of certain components used to manufacture the Inspire system. The current Supply Agreement expired on June 5, 2017, but was extended to allow Medtronic to complete a final build of the pressure sensor used in the Company’s original pressure sensing lead, which is expected to be completed in early 2018. Upon a change of control event whereby the Company is owned or controlled by a competitor of Medtronic, Medtronic would have the right to terminate the Supply Agreement, provided that, upon any such termination the Company would be entitled to exercise a one‑ time buy right of inventory using current product pricing and upon terms to be agreed upon in the definitive agreements. Development Agreement As part of the Development Agreement, Medtronic provided support to the Company for product development and was reimbursed on an hourly basis. The Medtronic services included project management, engineering, manufacturing, product quality, and testing of products. The Company continued to be responsible for all marketing, clinical, and regulatory efforts related to product development activities. The Development Agreement expired in 2015. The Company has transactions at arms- length with Medtronic, a related party. These transactions are summarized for the years ended December 31, 2015, 2016 and 2017 as follows: 2015 2016 2017 Inventory purchases $ 834 $ 848 $ 1,120 Research and development expenses 98 — — $ 932 $ 848 $ 1,120 Right‑of‑First‑Offer of the Company Under a Right- of- First- Offer with Medtronic that expired on May 16, 2017, had the Company decided to initiate a possible sale of the Company prior to the expiration date, it would have been required to negotiate exclusively with Medtronic for such transaction for a period of 90 days prior to negotiating with a third party. |
Income Taxes
Income Taxes | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Income Tax Disclosure [Abstract] | ||
Income Taxes | Income Taxes During the three and nine months ended September 30, 2018 and 2017 , we did not record an income tax benefit related to our loss before income taxes in the statement of operations and comprehensive loss because a valuation allowance has been required to be established for all deferred tax assets due to our cumulative net loss position. As of December 31, 2017 , our gross federal net operating loss carryforwards of $110.9 million will expire at various dates beginning in 2028. In addition, net operating loss carryforwards for state income tax purposes of $65.9 million that include net operating losses that will begin to expire in 2028. We also have R&D credit carryforwards of $1.4 million as of December 31, 2017 of which will expire at various dates beginning in 2032. Utilization of the net operating loss carryforwards may be subject to an annual limitation due to the ownership change limitations provided by Section 382 of the Internal Revenue Code of 1986 and similar state provisions. The annual limitation may result in the expiration of the net operating loss before utilization. Realization of the deferred tax assets is dependent upon the generation of future taxable income, if any, the amount and timing of which are uncertain. Based on available objective evidence and cumulative losses, management believes it is more likely than not that the deferred tax assets are not recognizable and will not be recognizable until we have sufficient taxable income. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. We had no unrecognized tax benefits as of September 30, 2018 and December 31, 2017 . We file income tax returns in the U.S. federal and various state jurisdictions. The 2014 to 2017 tax years remain open to examination by the major taxing authorities to which we are subject. We do not expect a significant change to our unrecognized tax benefits over the next 12 months . The Tax and Jobs Act (the "Act") was enacted on December 22, 2017. The Act reduces the U.S. federal corporate tax rate from 35% to 21% , requires companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax deferred and creates new taxes on certain foreign-sourced earnings. We have applied the guidance in ASU 2018-5, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 , when accounting for the enactment-date effects of the Act. At September 30, 2018 , we have not completed our accounting for the tax effects of the Act, as we are in the process of analyzing certain aspects of the Act, obtaining information, and refining our calculations of the Act's impact. There have been no material measurement period adjustments made during the nine months ended September 30, 2018 related to the provisional amounts recorded and disclosed in our Registration Statement Form S-1 and Prospectus dated May 2, 2018. We expect to complete the accounting for the tax effects of the Act during 2018. | 10. Income Taxes During the years ended December 31, 2015, 2016 and 2017, the Company did not record an income tax benefit related to its loss before income taxes in the statement of operations and comprehensive loss because a valuation allowance has been required to be established for all deferred tax assets due to its cumulative net loss position. The components of the Company’s provision for income taxes are as follows: Year ended December 31 2015 2016 2017 Tax at federal statutory rate 35.0 % 35.0 % 35.0 % State, net of federal benefit 2.4 2.8 3.0 Permanent items (0.8) (0.5) (1.1) Research and development (R&D) tax credit 1.4 1.3 1.2 Federal tax rate change — — (92.6) Other 4.5 7.1 1.1 Change in valuation allowance (42.5) (45.7) 53.4 Total — — — On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the Act) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system, and a one- time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. We have accounted for our best provisional estimate of the impact of the Act in our 2017 income tax provision, the period in which the legislation was enacted, in accordance with our understanding of the Act and guidance available as of the date of this filing. The provisional amount recorded related to the remeasurement of our deferred tax assets and liabilities, based on the lower tax rates at which they are expected to reverse in the future, was $16.2 million of expense. This tax expense was entirely offset by an income tax benefit related to the reduction of our deferred tax asset valuation allowance of the same amount, resulting in no net impact to tax expense or benefit. The Company also provisionally estimates that it does not have any foreign earnings and therefore is not subject to any one- time transition tax on the mandatory deemed repatriation of foreign earnings. Significant components of net deferred tax assets are as follows: December 31 2015 2016 2017 Deferred tax assets: Net operating losses $ 28,385 $ 36,626 $ 27,827 R&D tax credits 956 1,093 1,368 R&D expenditures, capitalized for tax 2,515 2,682 2,146 Accruals and other 1,165 1,065 753 33,020 41,466 32,094 Deferred tax liabilities: Depreciation and amortization (28) (4) 4 Net deferred tax assets 32,992 41,462 32,098 Valuation allowance (32,992) (41,462) (32,098) $ — $ — $ — Deferred income taxes reflect the tax effects of net operating loss and tax credit carryforwards and the net temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. As of December 31, 2017, the Company’s gross federal net operating loss carryforwards of $110.9 million will expire at various dates beginning in 2028. In addition, net operating loss carryforwards for state income tax purposes of $65.9 million that include net operating losses that will begin to expire in 2028. The Company also has R&D credit carryforwards of $1.4 million as of December 31, 2017 of which will expire at various dates beginning in 2032. Utilization of the net operating loss carryforwards may be subject to an annual limitation due to the ownership change limitations provided by Section 382 of the Internal Revenue Code of 1986 and similar state provisions. The annual limitation may result in the expiration of the net operating loss before utilization. Realization of the deferred tax assets is dependent upon the generation of future taxable income, if any, the amount and timing of which are uncertain. Based on available objective evidence and cumulative losses, management believes it is more likely than not that the deferred tax assets are not recognizable and will not be recognizable until the Company has sufficient taxable income. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $9.1 million and $8.5 million during the years ended December 31, 2015 and 2016, respectively, and decreased by $9.4 million during the year ended December 31, 2017. The Company had no unrecognized tax benefits as of December 31, 2016 and 2017. The Company files income tax returns in the U.S. federal and various state jurisdictions. The 2014 to 2017 tax years remain open to examination by the major taxing authorities to which the Company is subject. The Company does not expect a significant change to its unrecognized tax benefits over the next 12 months. The Company’s policy is to record interest related to uncertain tax positions as interest expense and any penalties as other expense in its statements of operations and comprehensive loss. There was no interest or penalties accrued at December 31, 2016 and 2017. |
Segment Reporting and Significa
Segment Reporting and Significant Customers | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Segment Reporting [Abstract] | ||
Segment Reporting and Significant Customers | Segment Reporting and Significant Customers Operating segments are defined as components of an enterprise for which separate discrete financial information is available and evaluated regularly by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. We globally manage the business within one reporting segment. Segment information is consistent with how management reviews the business, makes investing and resource allocation decisions and assesses operating performance. Revenue by geographic region is as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 United States $ 11,307 $ 6,547 $ 29,580 $ 15,922 Europe 1,747 724 4,454 2,688 Total revenue $ 13,054 $ 7,271 $ 34,034 $ 18,610 All of our long-lived assets are located in the United States. | 11. Segment Reporting and Significant Customers Operating segments are defined as components of an enterprise for which separate discrete financial information is available and evaluated regularly by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company globally manages the business within one reporting segment. Segment information is consistent with how management reviews the business, makes investing and resource allocation decisions and assesses operating performance. Revenue by geographic region are as follows: Year ended December 31, 2015 2016 2017 United States $ 6,132 $ 13,789 $ 24,293 Europe 1,880 2,638 4,274 Total revenue $ 8,012 $ 16,427 $ 28,567 All the Company’s long-lived assets are located in the United States. |
Loss Per Share
Loss Per Share | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Earnings Per Share [Abstract] | ||
Loss Per Share | Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because we have reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, convertible preferred stock warrants, convertible common stock warrants and common stock options were antidilutive in those periods. The following potentially dilutive securities outstanding at the end of the periods presented have been excluded from the computations of diluted shares outstanding because such securities have an antidilutive impact due to losses reported: September 30, 2018 2017 Convertible preferred stock outstanding — 12,111,706 Convertible preferred stock warrants — 65,434 Convertible common stock warrants 80,884 — Common stock options outstanding 2,198,130 2,074,994 Total 2,279,014 14,252,134 | 12. Loss Per Share Under the two- class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed. No such adjustment to earnings is made during periods with a net loss as the holders of the participating securities have no obligation to fund losses. Diluted net loss per common share is computed under the two- class method by using the weighted average number of shares of common stock outstanding plus, for periods with net income attributable to common stockholders, the potential dilutive effects of stock options and warrants. In addition, the Company analyzes the potential dilutive effect of the outstanding participating securities under the if- converted method when calculating diluted earnings per share in which it is assumed that the outstanding participating securities convert into common stock at the beginning of the period. The Company reports the more dilutive of the approaches (two- class or if- converted) as its diluted net income per share during the period. Due to the existence of net losses for the years ended December 31, 2015, 2016, and 2017, basic and diluted loss per share were the same, as the effect of potentially dilutive securities would have been anti- dilutive. The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an antidilutive impact due to losses reported: Year ended December 31, 2015 2016 2017 Convertible preferred stock outstanding 7,995,592 9,367,628 12,111,706 Convertible preferred stock warrants 367,598 394,587 423,784 Common stock options outstanding 1,541,163 1,497,511 2,071,616 9,904,353 11,259,726 14,607,106 |
Subsequent Events
Subsequent Events | 12 Months Ended |
Dec. 31, 2017 | |
Subsequent Events | |
Subsequent Events | 13. Subsequent Events The Company has evaluated events or transactions that may have occurred since December 31, 2017, that would merit recognition or disclosure in the financial statements. This evaluation was completed through February 14, 2018, the date the financial statements were available to be issued. On February 7, 2018, the Company borrowed an additional $8.0 million under the term B loan facility portion of its credit facility (see Note 4). After receipt of the $8.0 million, Company had a total of $24.5 million outstanding under the credit facility, which bears interest at a floating interest rate equal to the greater of 7.95% or LIBOR plus 6.9% per annum. All amounts borrowed under the credit facility are interest- only through March 1, 2019, after which the Company will make monthly payments of principal and interest through March 1, 2022; provided that the interest- only period will be extended will be extended to March 1, 2020 if the Company has revenue, measured on a trailing 12- month basis as of December 31, 2018, of at least $25.0 million. The Company issued 233,577 ten- year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. In connection with the initial public offering of the Company’s common stock (the “IPO”), the Company’s board of directors and stockholders approved a 1- for- 6.650 reverse stock split of the Company’s common stock. The reverse stock split became effective on April 20, 2018. The par value of the common stock was not adjusted as a result of the reverse stock split. Adjustments corresponding to the reverse stock split were made to the ratio at which the convertible preferred stock will convert into common stock immediately prior to the closing of the IPO. Accordingly, all share and per- share amounts for all periods presented in these financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect the reverse stock split and adjustment of the conversion ratio of the convertible preferred stock. |
Summary of Significant Accoun_2
Summary of Significant Accounting Policies (Policies) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Accounting Policies [Abstract] | ||
Basis of Presentation | Basis of Presentation The accompanying condensed financial statements have been prepared without audit, pursuant to the rules and regulations of the SEC. The condensed financial statements may not include all disclosures required by U.S. GAAP; however, we believe that the disclosures are adequate to make the information presented not misleading. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and the notes thereto for the fiscal year ended December 31, 2017 included in our audited consolidated financial statements for the year ended December 31, 2017 and the notes thereto for the year ended December 31, 2017 included in our final prospectus that forms a part of our Registration Statement on Form S-1 (File No. 333-224176), filed with the Securities and Exchange Commission ("SEC") pursuant to Rule 424(b)(4) on May 4, 2018 (the "Prospectus"). The condensed balance sheet at December 31, 2017 was derived from the audited financial statements. In the opinion of management, all adjustments, consisting of only normal recurring adjustments that are necessary to present fairly the financial position, results of operations, and cash flows for the interim periods, have been made. The results of operations for the interim periods are not necessarily indicative of the operating results for the full fiscal year or any future periods. Reverse Stock Split In connection with our initial public offering of common stock ("IPO"), our board of directors and stockholders approved a 1-for-6.650 reverse stock split of our common stock. The reverse stock split became effective on April 20, 2018. The par value of the common stock was not adjusted as a result of the reverse stock split. Adjustments corresponding to the reverse stock split were made to the ratio at which the convertible preferred stock will convert into common stock immediately prior to the closing of the IPO. Accordingly, all share and per-share amounts for all periods presented in these financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect the reverse stock split and adjustment of the conversion ratio of the convertible preferred stock. Initial Public Offering On May 7, 2018, we completed our IPO by issuing 7,762,500 shares of common stock, at an offering price of $16.00 per share, for net proceeds of approximately $112.0 million after deducting underwriting discounts and commissions and offering expenses payable by us. In connection with the IPO, our outstanding shares of convertible preferred stock were automatically converted into an aggregate of 12,111,706 shares of common stock, and our outstanding warrants to purchase shares of convertible preferred stock were automatically converted into warrants to purchase up to an aggregate of 100,558 shares of common stock, resulting in the reclassification of the related redeemable convertible preferred stock warrant liability of $0.9 million to additional paid-in capital ("APIC"). | Basis of Presentation The financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP). |
Use of Estimates | Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. We use significant judgment when making estimates related to the allowance for doubtful accounts, inventory reserves and the valuations of our common stock, share-based awards, and certain of our previously outstanding preferred stock warrants. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. | Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its allowance for doubtful accounts, inventory reserves and the valuations of its common stock, share‑based awards, and certain of its outstanding preferred stock warrants. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. |
JOBS Act Accounting Election | JOBS Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act"), we are eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. We have elected to take advantage of the extended transition period for adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. | JOBS Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act, the Company is eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. The Company has elected to take advantage of the extended transition period for adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. |
Cash and Cash Equivalents | Cash and Cash Equivalents We consider all highly liquid securities, readily convertible to cash, that mature within 90 days or less from the date of purchase to be cash equivalents. The carrying amount reported in the balance sheets for cash is cost, which approximates fair value. | Cash and Cash Equivalents The Company considers all highly liquid securities, readily convertible to cash, that mature within 90 days or less from the date of purchase to be cash equivalents. The carrying amount reported in the balance sheets for cash is cost, which approximates fair value. |
Short-term Investments | Short-Term Investments At September 30, 2018 and December 31, 2017 , our short-term investments consisted of commercial paper, corporate bonds, and U.S. government securities which are classified as available-for-sale and had maturities less than one year. Short-term investments are reported at their estimated fair market value which approximates cost. Any unrealized gains and losses are reported in accumulated other comprehensive loss. | Short‑term Investments The Company had no short-term investments at December 31, 2016. At December 31, 2017, the Company's short-term investments consisted of commercial paper and corporate bonds which are classified as available-for-sale and had maturities less than one year. Short-term investments are reported at their estimated fair market value which approximates cost at December 31, 2017. Any with unrealized gains and losses are reported in accumulated other comprehensive loss. |
Fair Value of Financial Instruments | Fair Value of Financial Instruments We measure certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents, short-term investments, and certain of our previously outstanding preferred stock warrants. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Observable inputs, such as quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Other inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs, including interest rate curves, foreign exchange rates, and credit ratings. Level 3—Unobservable inputs that are supported by little or no market activities, which would require us to develop our own assumptions. We use the methods and assumptions described below in determining the fair value of our financial instruments. Money market funds: Fair values of money market funds are based on quoted market prices in active markets. Commercial paper: Short-term, highly liquid investments are included as a Level 2 measurement in the tables below. Corporate bonds: Consists of notes, asset-backed securities and bonds with original maturities of less than one year and various yields. These are included as a Level 2 measurement in the tables below. U.S. government securities: Consists of U.S. Government treasury bills with original maturities of less than one year. These are included as a Level 1 measurement in the table below. The following tables sets forth by level within the fair value hierarchy our assets and liabilities that are reported at fair value as of September 30, 2018 and December 31, 2017 . As required by Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 820, Fair Value Measurement , assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of September 30, 2018 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 14,250 $ 14,250 $ — $ — Commercial paper 10,382 — 10,382 — Total cash equivalents 24,632 14,250 10,382 — Short-term investments: Commercial paper $ 47,631 $ — $ 47,631 $ — Corporate bonds 34,576 — 34,576 — U.S. government securities 11,907 11,907 — — Total short-term investments 94,114 11,907 82,207 — Total assets $ 118,746 $ 26,157 $ 92,589 $ — Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 $ — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 There were no transfers in and out of Level 1 and Level 2 fair value measurements during the periods ended September 30, 2018 and December 31, 2017 . The recurring Level 3 fair value measurements of our preferred stock warrant liabilities used the Black-Scholes option pricing model and value of the respective class of our convertible preferred stock (see Note 8 ), which was unobservable. All other assumptions included in the model are observable Level 1 inputs. The following table provides a reconciliation of the beginning and ending balances of our preferred stock warrant liabilities: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Balance at beginning of period $ — $ 57 $ 157 $ 53 Initial fair value of preferred stock warrants issued — — 103 4 Reclassified to equity — — (855 ) — Change in fair value of preferred stock warrants — — 595 — Balance at end of period $ — $ 57 $ — $ 57 Changes in the fair value of the preferred stock warrant liability were recorded in other expenses on the condensed statements of operations and comprehensive loss. In connection with the closing of the IPO in May 2018, warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock, resulting in the reclassification of the related convertible preferred stock warrant liability to APIC. | Fair Value of Financial Instruments The Company measures certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents and certain of its outstanding preferred stock warrants. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market‑based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three‑tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Observable inputs, such as quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Other inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model‑based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market‑based observable inputs, including interest rate curves, foreign exchange rates, and credit ratings. Level 3—Unobservable inputs that are supported by little or no market activities, which would require the Company to develop its own assumptions. The Company uses the methods and assumptions described below in determining the fair value of its financial instruments. Money market funds: Fair values of money market funds are based on quoted market prices in active markets. Commercial paper: Short‑term, highly liquid investments are included as a Level 2 measurement in the tables below. Corporate bonds: Consists of U.S. Government treasury bills, notes, and bonds with original maturities of less than one year and various yields. These are included as a Level 2 measurement in the tables below. The following tables sets forth by level within the fair value hierarchy the Company’s assets and liabilities that are reported at fair value as of December 31, 2016 and 2017. As required by Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 820, Fair Value Measurement , assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of December 31, 2016 Estimated Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ $ $ — $ — Liabilities Preferred stock warrants $ $ — $ — $ Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 There were no transfers in and out of Level 1 and Level 2 fair value measurements during the years ended December 31, 2016 and 2017. The recurring Level 3 fair value measurements of the Company's preferred stock warrant liabilities use the Black-Scholes option pricing model and value of the respective class of the Company's convertible preferred stock (see Note 7), which is unobservable. All other assumptions included in the model are observable Level 1 inputs. The following table provides a reconciliation of the beginning and ending balances of the Company's preferred stock warrant liabilities: Balance as of December 31, 2014 $ Initial fair value of preferred stock warrants issued 33 Change in fair value of preferred stock warrants 12 Balance as of December 31, 2015 248 Change in fair value of preferred stock warrants (195) Balance as of December 31, 2016 53 Initial fair value of preferred stock warrants issued Change in fair value of preferred stock warrants Balance as of December 31, 2017 $ 157 Changes in the fair value of the preferred stock warrant liability are recorded in other expenses on the statements of operations and comprehensive loss. |
Concentration of Credit Risk | Concentration of Credit Risk Financial instruments, which potentially subject us to concentrations of credit risk, consist principally of cash equivalents and accounts receivable. We believe that the credit risk in our accounts receivable is mitigated by our credit evaluation process, relatively short collection terms, and dispersion of our customer base. We generally do not require collateral, and losses on accounts receivable have historically been within management's expectations. Our investment policy limits investments to certain types of debt securities issued by the U.S. government and its agencies, corporations with investment-grade credit ratings, or commercial paper and money market funds issued by the highest quality financial and non-financial companies. We place restrictions on maturities and concentration by type and issuer. We are exposed to credit risk in the event of a default by the issuers of these securities to the extent recorded on the balance sheets. However, as of September 30, 2018 and December 31, 2017 , we limited our credit risk associated with cash equivalents by placing investments with banks we believe are highly creditworthy. | Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentrations of credit risk, consist principally of cash equivalents and accounts receivable. The Company believes that the credit risk in its accounts receivable is mitigated by its credit evaluation process, relatively short collection terms, and dispersion of its customer base. The Company generally does not require collateral, and losses on accounts receivable have historically been within management’s expectations. The Company’s investment policy limits investments to certain types of debt securities issued by the U.S. government and its agencies, corporations with investment‑grade credit ratings, or commercial paper and money market funds issued by the highest quality financial and non‑financial companies. The Company places restrictions on maturities and concentration by type and issuer. The Company is exposed to credit risk in the event of a default by the issuers of these securities to the extent recorded on the balance sheets. However, as of December 31, 2016 and 2017, the Company has limited its credit risk associated with its cash equivalents by placing its investments with banks it believes are highly creditworthy. |
Allowance for Doubtful Accounts | Allowance for Doubtful Accounts We record an allowance for doubtful accounts for accounts receivable deemed uncollectible. We evaluate the collectability of our accounts receivable based on known collection risks and historical experience. In circumstances where we are aware of a specific customer's inability to meet its financial obligations to us (e.g., bankruptcy filings, substantial downgrading of credit ratings), we record a specific allowance for bad debts against amounts due to reduce the carrying amount of accounts receivable to the amount we reasonably believe will be collected. | Allowance for Doubtful Accounts The Company records an allowance for doubtful accounts for accounts receivable deemed uncollectible. The Company evaluates the collectability of its accounts receivable based on known collection risks and historical experience. In circumstances where the Company is aware of a specific customer’s inability to meet its financial obligations to the Company (e.g., bankruptcy filings, substantial downgrading of credit ratings), the Company records a specific allowance for bad debts against amounts due to reduce the carrying amount of accounts receivable to the amount it reasonably believes will be collected. |
Inventories | Inventories Inventories are valued at the lower of cost or net realizable value, computed on a first-in, first out basis. We regularly review inventory quantities on-hand for excess and obsolete inventory and, when circumstances indicate, incur charges to write down inventories to their net realizable value. Our review of inventory for excess and obsolete quantities is based primarily on the estimated forecast of future product demand, product life cycles, including expiration of inventory prior to sale, and introduction of new products. | Inventories Inventories are valued at the lower of cost or net realizable value, computed on a first-in, first out basis. The Company regularly reviews inventory quantities on-hand for excess and obsolete inventory and, when circumstances indicate, incurs charges to write down inventories to their net realizable value. The Company's review of inventory for excess and obsolete quantities is based primarily on the estimated forecast of future product demand, product life cycles, including expiration of inventory prior to sale, and introduction of new products. The reserve for excess and obsolete inventory was $191 and $518 as of December 31, 2016 and 2017, respectively. |
Property and Equipment | Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. | Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight‑line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. |
Impairment of Long-lived Assets | Impairment of Long-lived Assets Long-lived assets consist primarily of property and equipment and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require that an asset be tested for possible impairment, we compare the undiscounted cash flows expected to be generated by the asset to the carrying amount of the asset. If the carrying amount of the asset is not recoverable on an undiscounted cash flow basis, we determine the fair value of the asset and recognize an impairment loss to the extent the carrying amount of the asset exceeds its fair value. We determine fair value using the income approach based on the present value of expected future cash flows or other appropriate measures of estimated fair value. Our cash flow assumptions consider historical and forecasted revenue and operating costs and other relevant factors. We did not record any impairment charges on long-lived assets during the nine months ended September 30, 2018 and 2017 . | Impairment of Long‑lived Assets Long‑lived assets consist primarily of property and equipment and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require that an asset be tested for possible impairment, the Company compares the undiscounted cash flows expected to be generated by the asset to the carrying amount of the asset. If the carrying amount of the asset is not recoverable on an undiscounted cash flow basis, the Company determines the fair value of the asset and recognizes an impairment loss to the extent the carrying amount of the asset exceeds its fair value. The Company determines fair value using the income approach based on the present value of expected future cash flows or other appropriate measures of estimated fair value. The Company’s cash flow assumptions consider historical and forecasted revenue and operating costs and other relevant factors. The Company did not record any impairment charges on long‑lived assets during the years ended December 31, 2015, 2016 and 2017. |
Revenue Recognition | Revenue Recognition We recognize revenue when persuasive evidence of an arrangement exists, product shipment has occurred, or there are no further obligations yet to be performed, pricing is fixed or determinable, and collection is reasonably assured. We make reasonable assumptions regarding the future collectability of amounts receivable from customers to determine whether the revenue recognition criteria have been met. Taxes assessed by a governmental authority that are directly imposed on revenue-producing transactions between a seller and a customer are not recorded as revenue. In general, our standard terms and conditions of sale do not allow for product returns. Sales returns have been limited to damaged product and have not been material. We expense shipping and handling costs as incurred and include them in the cost of goods sold. In those cases where shipping and handling costs are billed to customers, we classify the amounts billed as a component of cost of goods sold. | Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, product shipment has occurred, or there are no further obligations yet to be performed, pricing is fixed or determinable, and collection is reasonably assured. The Company makes reasonable assumptions regarding the future collectability of amounts receivable from customers to determine whether the revenue recognition criteria have been met. Taxes assessed by a governmental authority that are directly imposed on revenue‑producing transactions between a seller and a customer are not recorded as revenue. In general, the Company’s standard terms and conditions of sale do not allow for product returns. Sales returns have been limited to damaged product and have not been material. The Company expenses shipping and handling costs as incurred and includes them in the cost of goods sold. In those cases where shipping and handling costs are billed to customers, the Company classifies the amounts billed as a component of cost of goods sold. |
Cost of Goods Sold | Cost of Goods Sold Cost of goods sold consists primarily of manufacturing overhead costs, material costs, and direct labor. Overhead costs include the cost of material procurement, inventory control, facilities, equipment, and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs. | Cost of Goods Sold Cost of goods sold consists primarily of manufacturing overhead costs, material costs, and direct labor. Overhead costs include the cost of material procurement, inventory control, facilities, equipment, and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs. |
Research and Development | Research and Development Research and development expenses consist primarily of product development, clinical and regulatory affairs, consulting services, and other costs associated with products and technologies in development. These expenses include employee compensation, stock-based compensation, supplies, travel, and facility costs. Clinical expenses include clinical trial design, clinical site reimbursement, data management, travel expenses, and the cost of manufacturing products for clinical trials. | Research and Development Research and development expenses consist primarily of product development, clinical and regulatory affairs, consulting services, and other costs associated with products and technologies in development. These expenses include employee compensation, stock-based compensation, supplies, travel, and facility costs. Clinical expenses include clinical trial design, clinical site reimbursement, data management, travel expenses, and the cost of manufacturing products for clinical trials. |
Common Stock Valuation and Stock-Based Compensation | Common Stock Valuation and Stock-Based Compensation We maintain an equity incentive plan to provide long-term incentives for employees, consultants, and members of the board of directors. The plan allows for the issuance of non-statutory and incentive stock options to employees and non-statutory stock options to consultants and non-employee directors. We recognize equity-based compensation expense for awards of equity instruments to employees and non-employees based on the grant date fair value of those awards in accordance with FASB ASC Topic 718, Stock Compensation ("ASC 718"). ASC 718 requires all equity-based compensation awards to employees and nonemployee directors, including grants of restricted shares and stock options, to be recognized as expense in the statements of operations and comprehensive loss based on their grant date fair values. We estimate the fair value of stock options using the Black-Scholes option pricing model. We use the value of our common stock to determine the fair value of restricted shares. We account for restricted stock and common stock options issued to nonemployees under FASB ASC Topic 505-50, Equity-Based Payments to Non-Employees . As such, the value of such options is periodically remeasured and income or expense is recognized over their vesting terms. Compensation cost related to awards with service-based vesting schedules is recognized using the straight-line method. We determine the fair value of the restricted stock and common stock granted to nonemployees as either the fair value of the consideration received or the fair value of the equity instruments issued. We have not granted any share-based awards to our consultants. The Black-Scholes option pricing model requires the input of certain subjective assumptions, including (i) the expected share price volatility, (ii) the expected term of the award, (iii) the risk-free interest rate and (iv) the expected dividend yield. Due to the lack of a public market for the trading of our common stock and a lack of company-specific historical and implied volatility data, we have based our estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The group of representative companies have characteristics similar to us, including stage of product development and focus on the life science industry. We use the simplified method, which is the average of the final vesting tranche date and the contractual term, to calculate the expected term for options granted to employees as we do not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. For options granted to non-employees, we utilize the contractual term of the arrangement as the basis for the expected term assumption. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. We use an assumed dividend yield of zero as we have never paid dividends and have no current plans to pay any dividends on our common stock. We expense the fair value of our equity-based compensation awards granted to employees on a straight-line basis over the associated service period, which is generally the period in which the related services are received. We measure equity-based compensation awards granted to nonemployees at fair value as the awards vest and recognize the resulting value as compensation expense at each financial reporting period. We account for award forfeitures as they occur. | Common Stock Valuation and Stock‑Based Compensation The Company maintains an equity incentive plan to provide long-term incentives for employees, consultants, and members of the board of directors. The plan allows for the issuance of non-statutory and incentive stock options to employees and non-statutory stock options to consultants and non-employee directors. The Company recognizes equity‑based compensation expense for awards of equity instruments to employees and non‑employees based on the grant date fair value of those awards in accordance with FASB ASC Topic 718, Stock Compensation (ASC 718). ASC 718 requires all equity‑based compensation awards to employees and nonemployee directors, including grants of restricted shares and stock options, to be recognized as expense in the statements of operations and comprehensive loss based on their grant date fair values. The Company estimates the fair value of stock options using the Black‑Scholes option pricing model. The Company uses the value of its common stock to determine the fair value of restricted shares. The Company accounts for restricted stock and common stock options issued to nonemployees under FASB ASC Topic 505‑50, Equity‑Based Payments to Non‑Employees (ASC 505‑50). As such, the value of such options is periodically remeasured and income or expense is recognized over their vesting terms. Compensation cost related to awards with service‑based vesting schedules is recognized using the straight‑line method. The Company determines the fair value of the restricted stock and common stock granted to nonemployees as either the fair value of the consideration received or the fair value of the equity instruments issued. The Company has not granted any share‑based awards to its consultants. The Black‑Scholes option pricing model requires the input of certain subjective assumptions, including (i) the expected share price volatility, (ii) the expected term of the award, (iii) the risk‑free interest rate and (iv) the expected dividend yield. Due to the lack of a public market for the trading of the Company’s common stock and a lack of company‑specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The group of representative companies have characteristics similar to the Company, including stage of product development and focus on the life science industry. The Company uses the simplified method, which is the average of the final vesting tranche date and the contractual term, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. For options granted to non‑employees, the Company utilizes the contractual term of the arrangement as the basis for the expected term assumption. The risk‑free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The Company uses an assumed dividend yield of zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock. The Company expenses the fair value of its equity‑based compensation awards granted to employees on a straight‑line basis over the associated service period, which is generally the period in which the related services are received. The Company measures equity‑based compensation awards granted to nonemployees at fair value as the awards vest and recognizes the resulting value as compensation expense at each financial reporting period. The Company accounts for award forfeitures as they occur. |
Advertising Expenses | Advertising Expenses We expense the costs of advertising, including promotional expenses, as incurred. | Advertising Expenses The Company expenses the costs of advertising, including promotional expenses, as incurred. Advertising expenses were $2.2 million, $3.4 million and $5.5 million during the years ended December 31, 2015, 2016, and 2017, respectively. |
Income Taxes | Income Taxes We account for income taxes using the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates that will be in effect when the differences are expected to reverse. Valuation allowances against deferred tax assets are established, when necessary, to reduce deferred tax assets to the amounts expected to be realized. As we have historically incurred operating losses, we have recorded a full valuation allowance against our net deferred tax assets, and there is no provision for income taxes. Our policy is to record interest and penalties expense related to uncertain tax positions as other expense in the statements of operations and comprehensive loss. | Income Taxes The Company accounts for income taxes using the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates that will be in effect when the differences are expected to reverse. Valuation allowances against deferred tax assets are established, when necessary, to reduce deferred tax assets to the amounts expected to be realized. As the Company has historically incurred operating losses, the Company has recorded a full valuation allowance against its net deferred tax assets, and there is no provision for income taxes. The Company's policy is to record interest and penalties expense related to uncertain tax positions as other expense in the statements of operations and comprehensive loss. |
Comprehensive Loss | Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on short-term investments classified as available-for-sale, if any. Accumulated other comprehensive loss is presented in the accompanying balance sheets as a component of stockholders' equity, if any. | Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on short‑term investments classified as available‑for‑sale, if any. Accumulated other comprehensive loss is presented in the accompanying balance sheets as a component of stockholders’ (deficit) equity. |
Loss Per Share | Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because we have reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, stock options and warrants were antidilutive in those periods. | Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because the Company has reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, stock options and warrants were antidilutive in those periods. |
Recent Accounting Pronouncements | Recent Accounting Pronouncements We are an “emerging growth company” as defined by the JOBS Act. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act of 1933, as amended, (the "Securities Act"), for complying with new or revised accounting standards. Accordingly, an emerging growth company can selectively delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this exemption and, as a result, our financial statements may not be comparable to the financial statements of issuers that are required to comply with the effective dates for new or revised accounting standards that are applicable to public companies. Section 107 of the JOBS Act provides that we can elect to opt out of the extended transition period at any time, which election is irrevocable. In May 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers . The new section will replace Section 605, Revenue Recognition , and creates modifications to various other revenue accounting standards for specialized transactions and industries. The section is intended to conform revenue accounting principles with the concurrently issued International Financial Reporting Standards to reconcile previously differing treatment between U.S. practices and those of the rest of the world and to enhance disclosures related to disaggregated revenue information. The updated guidance is effective for interim and annual reporting periods beginning on or after December 15, 2018 for private companies and, therefore, us due to the JOBS Act exemption described above. We have commenced project planning for our implementation, which has included engaging an accounting firm to assist us. We have not yet made a determination on our transition method, nor have we determined whether this standard will have a material impact on our financial statements. We plan to complete our assessment of the impact of this standard during the fourth quarter of 2018. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes ("ASU 2015-17"). ASU 2015-17 is intended to reduce complexity surrounding the presentation of deferred taxes within the balance sheet. Specifically, ASU 2015-17 requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non-current on the balance sheet, effectively eliminating the requirement to allocate deferred taxes between current and non-current amounts. The new guidance does not permit companies to offset deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. This guidance was effective January 1, 2018 and did not significantly impact our financial statements and related disclosures. In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842), which supersedes the existing guidance for lease accounting, Leases (Topic 840). ASU 2016-02 requires lessees to recognize a lease liability and a right-of-use asset for all leases. Lessor accounting remains largely unchanged. The amendments in this ASU are effective for interim and annual periods beginning after December 15, 2019 for private companies; and, therefore, us due to the JOBS Act exemption described above. Early adoption is permitted for all entities. ASU 2016-02 requires a modified retrospective approach for all leases existing at, or entered into after, the date of initial adoption, with an option to elect to use certain transition relief. We plan to further evaluate the anticipated impact of the adoption of this ASU on our financial statements in future periods. In March 2016, the FASB issued No. 2016-9, Improvements to Employee Share-Based Payment Accounting ("ASU 2016-9"), which changes how companies will account for certain aspects of share-based payments to employees. As part of the new guidance, entities will be required to record the impact of income taxes arising from share-based compensation when awards vest or are settled within earnings as part of income tax expense rather than recorded as part of APIC and will eliminate the requirement that excess tax benefits be realized prior to recognition. Additionally, the guidance requires entities to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. Additionally, companies will be required to make an accounting policy election at the time of adoption of the new guidance to either account for forfeitures of share-based awards in a manner similar to today's requirements (i.e., estimating the number of awards expected to be forfeited at the grant date and adjusting the estimate when awards are actually forfeited), or recognizing forfeitures as they occur with no estimate of forfeitures determined at the grant date. Companies will also be able to set a maximum statutory tax rate as it pertains to share-based awards it net settles on behalf of its employees. This will provide companies a greater ability to retain equity-award accounting treatment. Entities will apply the provisions of ASU 2016-9 using a modified retrospective transition approach, with a cumulative-effect adjustment booked to retained earnings as of the beginning of the period of adoption. This guidance was effective for us on January 1, 2018 and did not significantly impact our financial statements and related disclosures. We have reviewed and considered all other recent accounting pronouncements and believe there are none that could potentially have a material impact on our business practices, financial condition, results of operations, or disclosures. | Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (ASU) No. 2014‑09, Revenue From Contracts With Customers (ASU 2014‑09), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014‑09 will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. In doing so, companies will need to use more judgment and make more estimates than under current guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price, and allocating the transaction price to each separate performance obligation. Under the original pronouncement, ASU 2014‑09 would have been effective for the Company’s annual reporting periods beginning January 1, 2018. In August 2015, the FASB issued ASU No. 2015‑14, which formally defers the effective date of the new revenue standard by one year. As a result, the updated revenue guidance will be effective for the Company’s annual reporting periods beginning January 1, 2019, and early adoption is permitted as of the original effective date contained within the original standard. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that ASU 2014‑09 will have on its financial statements and related disclosures. In July 2015, the FASB issued ASU 2015‑11 Simplifying the Measurement of Inventory , which is intended to narrow down the alternative methods available for valuing inventory. The new guidance does not apply to inventory currently measured using the last‑in‑first‑out or the retail inventory valuation methods. Under the new guidance, inventory valued using other methods, including the first‑in‑first‑out method, must be valued at the lower of cost or net realizable value. This guidance is effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2016. This guidance was effective January 1, 2017 and did not have a material impact on the Company’s financial position, results of operations and cash flows. In November 2015, the FASB issued ASU No. 2015‑17, Balance Sheet Classification of Deferred Taxes (ASU 2015‑17). ASU 2015‑17 is intended to reduce complexity surrounding the presentation of deferred taxes within the balance sheet. Specifically, ASU 2015‑17 requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non‑current on the balance sheet, effectively eliminating the requirement to allocate deferred taxes between current and non‑current amounts. The new guidance does not permit companies to offset deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. ASU 2015‑17 will be effective for the Company’s annual reporting periods beginning January 1, 2018, and can be applied on either a prospective or retrospective basis; early adoption is also permitted. The Company does not expect the ASU 2015‑17 to significantly impact its financial statements and related disclosures. In February 2016, the FASB issued ASU No. 2016‑02, Leases (ASU 2016‑02). ASU 2016‑02 will require entities that lease assets to recognize the rights and obligations associated with those leases on their balance sheets. The guidance will be effective for the Company’s annual reporting period beginning January 1, 2020, with early adoption permitted. The Company is evaluating the impact this standard will have on its financial statements and related disclosures. In March 2016, the FASB issued No. 2016‑09, Improvements to Employee Share‑Based Payment Accounting (ASU 2016‑09), which changes how companies will account for certain aspects of share‑based payments to employees. As part of the new guidance, entities will be required to record the impact of income taxes arising from share‑based compensation when awards vest or are settled within earnings as part of income tax expense rather than recorded as part of additional paid‑in capital (APIC) and will eliminate the requirement that excess tax benefits be realized prior to recognition. Additionally, the guidance requires entities to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. Additionally, companies will be required to make an accounting policy election at the time of adoption of the new guidance to either account for forfeitures of share‑based awards in a manner similar to today’s requirements (i.e., estimating the number of awards expected to be forfeited at the grant date and adjusting the estimate when awards are actually forfeited), or recognizing forfeitures as they occur with no estimate of forfeitures determined at the grant date. Companies will also be able to set a maximum statutory tax rate as it pertains to share‑based awards it net settles on behalf of its employees. This will provide companies a greater ability to retain equity‑award accounting treatment. Entities will apply the provisions of ASU 2016‑09 using a modified retrospective transition approach, with a cumulative‑effect adjustment booked to retained earnings as of the beginning of the period of adoption. The guidance will be effective for the Company’s annual reporting periods beginning January 1, 2018, with early adoption permitted. The Company is evaluating the impact this standard will have on its financial statements and related disclosures. The Company has reviewed and considered all other recent accounting pronouncements and believes there are none that could potentially have a material impact on its business practices, financial condition, results of operations, or disclosures. |
Summary of Significant Accoun_3
Summary of Significant Accounting Policies (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Accounting Policies [Abstract] | ||
Schedule of assets and liabilities measured at fair value on a recurring basis | The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of September 30, 2018 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 14,250 $ 14,250 $ — $ — Commercial paper 10,382 — 10,382 — Total cash equivalents 24,632 14,250 10,382 — Short-term investments: Commercial paper $ 47,631 $ — $ 47,631 $ — Corporate bonds 34,576 — 34,576 — U.S. government securities 11,907 11,907 — — Total short-term investments 94,114 11,907 82,207 — Total assets $ 118,746 $ 26,157 $ 92,589 $ — Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 $ — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 | Fair Value Measurements as of December 31, 2016 Estimated Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ $ $ — $ — Liabilities Preferred stock warrants $ $ — $ — $ Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 |
Schedule of reconciliation of preferred stock warrant liabilities | The following table provides a reconciliation of the beginning and ending balances of our preferred stock warrant liabilities: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Balance at beginning of period $ — $ 57 $ 157 $ 53 Initial fair value of preferred stock warrants issued — — 103 4 Reclassified to equity — — (855 ) — Change in fair value of preferred stock warrants — — 595 — Balance at end of period $ — $ 57 $ — $ 57 Changes in the fair value of the preferred stock warrant liability were recorded in other expenses on the condensed statements of operations and comprehensive loss. In connection with the closing of the IPO in May 2018, warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock, resulting in the reclassification of the related convertible preferred stock warrant liability to APIC. | The following table provides a reconciliation of the beginning and ending balances of the Company's preferred stock warrant liabilities: Balance as of December 31, 2014 $ Initial fair value of preferred stock warrants issued 33 Change in fair value of preferred stock warrants 12 Balance as of December 31, 2015 248 Change in fair value of preferred stock warrants (195) Balance as of December 31, 2016 53 Initial fair value of preferred stock warrants issued Change in fair value of preferred stock warrants Balance as of December 31, 2017 $ 157 |
Composition of Certain Financ_2
Composition of Certain Financial Statement Items (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Composition of Certain Financial Statement Items | ||
Schedule of inventory | Inventories September 30, 2018 December 31, 2017 Raw materials $ 1,054 $ 1,323 Finished goods 2,021 2,347 Total inventories, net of reserves $ 3,075 $ 3,670 | December 31, 2016 2017 Raw materials $ 738 $ 1,323 Finished goods 2,617 2,347 $ 3,355 $ 3,670 |
Schedule of property and equipment | Property and Equipment September 30, 2018 December 31, 2017 Computer equipment and software $ 333 $ 351 Furniture and office equipment 148 137 Manufacturing equipment 857 1,108 Research and development equipment 30 30 Leasehold improvements 185 178 Property and equipment, cost 1,553 1,804 Less: accumulated depreciation and amortization (788 ) (810 ) Property and equipment, net $ 765 $ 994 | December 31, 2016 2017 Computer equipment and software $ 75 $ 351 Furniture and office equipment 84 137 Manufacturing equipment 1,329 1,108 Research and development equipment 34 30 Leasehold improvements 26 178 1,548 1,804 Less: accumulated depreciation and amortization (681) (810) $ 867 $ 994 |
Schedule of accrued expenses | Accrued Expenses September 30, 2018 December 31, 2017 Payroll and commissions payable $ 3,619 $ 2,871 Vacation 946 723 Other accrued expenses 397 438 Total accrued expenses $ 4,962 $ 4,032 | December 31, 2016 2017 Payroll and commissions payable $ 1,861 $ 2,871 Vacation 564 723 Other accrued expenses 279 438 $ 2,704 $ 4,032 |
Long-Term Debt (Tables)
Long-Term Debt (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Long-term Debt, by Current and Noncurrent [Abstract] | ||
Schedule of expected future principal payments for the credit facility | Expected future principal payments for the credit facility are as follows: Year ending December 31 : 2018 (remaining) $ — 2019 — 2020 10,208 2021 12,250 2022 2,042 Total expected future principal payments $ 24,500 | Year ending December 31: 2018 $ — 2019 4,583 2020 5,500 2021 5,500 2022 917 $ 16,500 |
Commitments (Tables)
Commitments (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Commitments and Contingencies Disclosure [Abstract] | ||
Schedule of future minimum annual operating lease payments | Future minimum annual operating lease payments are as follows: Year ending December 31 : 2018 (remaining) $ 48 2019 1,043 2020 952 Total future operating lease payments $ 2,043 | Years ending December 31: 2018 $ 190 2019 48 Total $ 238 |
Stockholders' Equity (Tables)
Stockholders' Equity (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Stockholders' Equity Note [Abstract] | ||
Summary of the Company's preferred stock and its terms | A summary of preferred stock and its terms as of December 31, 2017, is as follows: Series Shares Authorized Shares Issued and Outstanding Carrying Value Liquidation Preference per Share 8% Dividend per Share Conversion Price per Share A 5,375,507 5,375,507 $ 5,037 $ 1.00 $ 0.08 $ 6.65 B 8,706,909 8,706,909 15,913 1.84 0.15 9.91 C 14,091,589 13,829,906 14,949 1.07 0.09 7.12 D 5,683,292 5,683,292 6,043 1.07 0.09 7.12 E 15,373,091 15,267,175 39,848 2.62 0.21 15.16 F 27,664,232 27,372,261 37,316 1.37 0.11 9.11 Total 76,894,620 76,235,050 $ 119,106 | 2016 Shares Shares Issued and Carrying Series Authorized Outstanding Value A 5,375,507 5,375,507 $ 5,037 B 8,706,909 8,706,909 15,913 C 14,091,589 13,829,906 14,949 D 5,683,292 5,683,292 6,043 E 15,373,091 15,267,175 39,848 F 9,124,084 9,124,084 12,348 58,354,472 57,986,873 $ 94,138 2017 Shares Shares Issued and Carrying Series Authorized Outstanding Value A 5,375,507 5,375,507 $ 5,037 B 8,706,909 8,706,909 15,913 C 14,091,589 13,829,906 14,949 D 5,683,292 5,683,292 6,043 E 15,373,091 15,267,175 39,848 F 27,664,232 27,372,261 37,316 76,894,620 76,235,050 $ 119,106 A summary of the Company’s convertible preferred stock terms is as follows: Liquidation 8% Conversion Preference Dividend Price per Series per Share per Share Share A $ $ $ B C D E F |
Summary of preferred stock warrants issued under the company's original credit facility and subsequent amendments | As of May 7, 2018, the date of the closing of our IPO, the following preferred stock warrants issued under the original credit facility and subsequent amendments were outstanding and exercisable: Issuance Expiration Series Exercise Price Warrants Outstanding at May 7, 2018 Initial Value Fair Value at May 7, 2018 February 8, 2018 February 8, 2028 F $ 1.37 233,577 $ 103 $ 320 February 24, 2017 February 24, 2027 F 1.37 29,197 4 40 August 7, 2015 August 7, 2025 E 2.62 29,580 33 41 June 27, 2014 June 27, 2024 E 2.62 76,334 85 174 August 5, 2013 August 5, 2023 C 1.07 74,768 39 80 November 16, 2012 November 16, 2022 C 1.07 186,916 96 200 Total 630,372 $ 855 As of December 31, 2017, the following preferred stock warrants issued under the original credit facility and subsequent amendments were outstanding and exercisable: Issuance Expiration Series Exercise Price Warrants Outstanding at December 31, 2017 Initial Value Fair Value at December 31, 2017 February 24, 2017 February 24, 2027 F $ 1.37 29,197 $ 4 $ 13 August 7, 2015 August 7, 2025 E 2.62 29,580 33 8 June 27, 2014 June 27, 2024 E 2.62 76,334 85 21 August 5, 2013 August 5, 2023 C 1.07 74,768 39 33 November 16, 2012 November 16, 2022 C 1.07 186,916 96 82 Total 396,795 $ 157 | Warrants Fair Outstanding at Value at Dates Exercise December 31, Initial December 31, Issuance Expiration Series Price 2016 Value 2016 August 7, 2015 August 7, 2025 E $ 2.62 29,580 $ 33 $ 4 June 27, 2014 June 27, 2024 E 2.62 76,334 85 10 August 5, 2013 August 5, 2023 C 1.07 74,768 39 11 November 16, 2012 November 16, 2022 C 1.07 186,916 96 28 367,598 $ 53 Warrants Fair Outstanding at Value at Dates Exercise December 31, Initial December 31, Issuance Expiration Series Price 2017 Value 2017 February 24, 2017 February 24, 2027 F $ 1.37 29,197 $ 4 $ 13 August 7, 2015 August 7, 2025 E 2.62 29,580 33 8 June 27, 2014 June 27, 2024 E 2.62 76,334 85 21 August 5, 2013 August 5, 2023 C 1.07 74,768 39 33 November 16, 2012 November 16, 2022 C 1.07 186,916 96 82 396,795 $ 157 |
Stock Options (Tables)
Stock Options (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | ||
Summary of the Company's stock option activity and related information | A summary of stock option activity and related information is as follows: Options Weighted Average Exercise Price Weighted average remaining contractual term (years) Aggregate intrinsic value (in thousands) Outstanding at December 31, 2017 2,071,616 $ 1.47 5.9 Granted 385,056 $ 15.04 Exercised (227,114 ) $ 1.90 Forfeited (31,428 ) $ 1.05 Outstanding at September 30, 2018 2,198,130 $ 3.80 6.8 $ 84,136 Exercisable at September 30, 2018 1,307,821 $ 1.58 5.4 $ 52,975 | Weighted Average Options Exercise Price Outstanding at December 31, 2014 1,534,672 $ 1.77 Granted 49,235 2.07 Exercised (21,545) 1.96 Forfeited (21,199) 1.15 Outstanding at December 31, 2015 1,541,163 1.77 Granted 120,277 1.65 Exercised (109,079) 1.74 Forfeited (54,850) 1.87 Outstanding at December 31, 2016 1,497,511 1.76 Granted 721,763 0.94 Exercised (127,122) 1.85 Forfeited (20,536) 1.88 Outstanding at December 31, 2017 2,071,616 1.47 Exercisable at December 31, 2017 1,236,255 1.75 |
Schedule of stock compensation recognized, before taxes | Total stock-based compensation recognized, before taxes, during the three and nine months ended September 30, 2018 and 2017 , is as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 General and administrative $ 326 $ 41 $ 592 $ 89 Sales and marketing 41 30 88 73 Research and development 5 10 16 27 Total stock-based compensation $ 372 $ 81 $ 696 $ 189 | Year ended December 31 2015 2016 2017 General and administrative $ 147 $ 108 $ 116 Sales and marketing 99 90 84 Research and development 59 50 43 $ 305 $ 248 $ 243 |
Summary of weighted average assumptions for fair value of options granted | The fair value of options granted to employees and non-employee directors during the nine months ended September 30, 2018 and 2017 was estimated as of the grant date using the Black-Scholes option pricing model using the following assumptions: Nine Months Ended September 30, 2018 2017 Expected life (years) 5.50 - 6.25 5.75 - 6.25 Expected volatility 37.5 - 49.8% 39.9 - 41.5% Risk-free interest rate 2.38 - 3.01% 1.88 - 2.32% Dividend yield 0.0% 0.0% Weighted average fair value $7.43 $0.40 | Year ended December 31, 2015 2016 2017 Expected life (years) Expected volatility % % % Risk-free interest rate 1.65 - 2.14 % 1.27 - 2.25 % 1.88 - 2.32 % Dividend yield 0.0 % 0.0 % 0.0 % Weighted average fair value $ 0.86 $ 0.47 $ 0.40 |
Related Party Transactions (Tab
Related Party Transactions (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Related Party Transactions [Abstract] | |
Schedule of transactions at arms-length with a related party | 2015 2016 2017 Inventory purchases $ 834 $ 848 $ 1,120 Research and development expenses 98 — — $ 932 $ 848 $ 1,120 |
Income Taxes (Tables)
Income Taxes (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Income Tax Disclosure [Abstract] | |
Schedule of components of the Company's provision for income taxes | Year ended December 31 2015 2016 2017 Tax at federal statutory rate 35.0 % 35.0 % 35.0 % State, net of federal benefit 2.4 2.8 3.0 Permanent items (0.8) (0.5) (1.1) Research and development (R&D) tax credit 1.4 1.3 1.2 Federal tax rate change — — (92.6) Other 4.5 7.1 1.1 Change in valuation allowance (42.5) (45.7) 53.4 Total — — — |
Schedule of significant components of net deferred tax assets | December 31 2015 2016 2017 Deferred tax assets: Net operating losses $ 28,385 $ 36,626 $ 27,827 R&D tax credits 956 1,093 1,368 R&D expenditures, capitalized for tax 2,515 2,682 2,146 Accruals and other 1,165 1,065 753 33,020 41,466 32,094 Deferred tax liabilities: Depreciation and amortization (28) (4) 4 Net deferred tax assets 32,992 41,462 32,098 Valuation allowance (32,992) (41,462) (32,098) $ — $ — $ — |
Segment Reporting and Signifi_2
Segment Reporting and Significant Customers (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Segment Reporting [Abstract] | ||
Schedule of revenue by geographic region | Revenue by geographic region is as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 United States $ 11,307 $ 6,547 $ 29,580 $ 15,922 Europe 1,747 724 4,454 2,688 Total revenue $ 13,054 $ 7,271 $ 34,034 $ 18,610 | Year ended December 31, 2015 2016 2017 United States $ 6,132 $ 13,789 $ 24,293 Europe 1,880 2,638 4,274 Total revenue $ 8,012 $ 16,427 $ 28,567 |
Loss Per Share (Tables)
Loss Per Share (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Earnings Per Share [Abstract] | ||
Schedule of dilutive securities excluded from computations of diluted weighted average shares outstanding | The following potentially dilutive securities outstanding at the end of the periods presented have been excluded from the computations of diluted shares outstanding because such securities have an antidilutive impact due to losses reported: September 30, 2018 2017 Convertible preferred stock outstanding — 12,111,706 Convertible preferred stock warrants — 65,434 Convertible common stock warrants 80,884 — Common stock options outstanding 2,198,130 2,074,994 Total 2,279,014 14,252,134 | Year ended December 31, 2015 2016 2017 Convertible preferred stock outstanding 7,995,592 9,367,628 12,111,706 Convertible preferred stock warrants 367,598 394,587 423,784 Common stock options outstanding 1,541,163 1,497,511 2,071,616 9,904,353 11,259,726 14,607,106 |
Summary of Significant Accoun_4
Summary of Significant Accounting Policies - Short-term Investments and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Accumulated other comprehensive loss | $ (26) | $ 0 | $ 0 |
Short-term investments: | |||
Total short-term investments | 94,114 | 7,188 | 0 |
Liabilities | |||
Preferred stock warrants | 0 | 157 | 53 |
Fair value of assets transferred from Level 1 to Level 2 | 0 | 0 | 0 |
Fair value of assets transferred from Level 2 to Level 1 | 0 | 0 | 0 |
Fair value of liabilities transferred from Level 1 to Level 2 | 0 | 0 | 0 |
Fair value of liabilities transferred from Level 2 to Level 1 | 0 | 0 | 0 |
Recurring basis | |||
Cash equivalents: | |||
Money market funds | 14,250 | 6,446 | 5,084 |
Commercial paper | 10,382 | 1,099 | |
Total cash equivalents | 24,632 | 7,545 | |
Short-term investments: | |||
Commercial paper | 47,631 | 5,384 | |
Corporate bonds | 34,576 | 1,804 | |
Total short-term investments | 94,114 | 7,188 | |
Total assets | 118,746 | 14,733 | |
Liabilities | |||
Preferred stock warrants | 157 | 53 | |
Level 1 | Recurring basis | |||
Cash equivalents: | |||
Money market funds | 14,250 | 6,446 | 5,084 |
Commercial paper | 0 | 0 | |
Total cash equivalents | 14,250 | 6,446 | |
Short-term investments: | |||
Commercial paper | 0 | 0 | |
Corporate bonds | 0 | 0 | |
Total short-term investments | 11,907 | 0 | |
Total assets | 26,157 | 6,446 | |
Liabilities | |||
Preferred stock warrants | 0 | ||
Level 2 | Recurring basis | |||
Cash equivalents: | |||
Money market funds | 0 | 0 | |
Commercial paper | 10,382 | 1,099 | |
Total cash equivalents | 10,382 | 1,099 | |
Short-term investments: | |||
Commercial paper | 47,631 | 5,384 | |
Corporate bonds | 34,576 | 1,804 | |
Total short-term investments | 82,207 | 7,188 | |
Total assets | 92,589 | 8,287 | |
Liabilities | |||
Preferred stock warrants | 0 | ||
Level 3 | Recurring basis | |||
Cash equivalents: | |||
Money market funds | 0 | 0 | |
Commercial paper | 0 | 0 | |
Total cash equivalents | 0 | 0 | |
Short-term investments: | |||
Commercial paper | 0 | 0 | |
Corporate bonds | 0 | 0 | |
Total short-term investments | 0 | 0 | |
Total assets | $ 0 | 0 | |
Liabilities | |||
Preferred stock warrants | $ 157 | $ 53 |
Summary of Significant Accoun_5
Summary of Significant Accounting Policies - Reconciliation of Preferred Stock Warrant Liabilities (Details) - Preferred stock warrant - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Reconciliation of preferred stock warrant liabilities: | |||||
Balance at beginning of period | $ 157 | $ 53 | $ 53 | $ 248 | $ 203 |
Initial fair value of preferred stock warrants issued | 103 | 4 | 4 | 33 | |
Change in fair value of preferred stock warrants | $ 595 | 0 | 100 | (195) | 12 |
Balance at end of period | $ 57 | $ 157 | $ 53 | $ 248 |
Summary of Significant Accoun_6
Summary of Significant Accounting Policies - Inventories (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Accounting Policies [Abstract] | |||
Reserve for excess and obsolete inventory | $ 813 | $ 518 | $ 191 |
Summary of Significant Accoun_7
Summary of Significant Accounting Policies - Property and Equipment (Details) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Minimum | ||
Property and Equipment | ||
Estimated useful lives | 3 years | 3 years |
Maximum | ||
Property and Equipment | ||
Estimated useful lives | 7 years | 7 years |
Summary of Significant Accoun_8
Summary of Significant Accounting Policies - Stock Based Compensation (Details) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Accounting Policies [Abstract] | ||
Dividend yield | 0.00% | 0.00% |
Summary of Significant Accoun_9
Summary of Significant Accounting Policies - Advertising Expenses (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Advertising Expenses | |||||
Advertising expenses | $ 5.8 | $ 3.7 | $ 5.5 | $ 3.4 | $ 2.2 |
Summary of Significant Accou_10
Summary of Significant Accounting Policies - Income Taxes (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | ||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | |
Income Taxes | ||||
Provision for income taxes | $ 0 | $ 0 | $ 0 | $ 0 |
Composition of Certain Financ_3
Composition of Certain Financial Statement Items - Inventories (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Composition of Certain Financial Statement Items | |||
Raw materials | $ 1,054 | $ 1,323 | $ 738 |
Finished goods | 2,021 | 2,347 | 2,617 |
Total inventories, net of reserves | $ 3,075 | $ 3,670 | $ 3,355 |
Composition of Certain Financ_4
Composition of Certain Financial Statement Items - Property and Equipment (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Property and Equipment | |||||
Property and equipment, gross | $ 1,553 | $ 1,804 | $ 1,548 | ||
Less: accumulated depreciation | (788) | (810) | (681) | ||
Property and equipment, net | 765 | 994 | 867 | ||
Depreciation and amortization expenses | 288 | $ 174 | 285 | 103 | $ 120 |
Computer equipment and software | |||||
Property and Equipment | |||||
Property and equipment, gross | 333 | 351 | 75 | ||
Furniture and office equipment | |||||
Property and Equipment | |||||
Property and equipment, gross | 148 | 137 | 84 | ||
Manufacturing equipment | |||||
Property and Equipment | |||||
Property and equipment, gross | 857 | 1,108 | 1,329 | ||
Research and development equipment | |||||
Property and Equipment | |||||
Property and equipment, gross | 30 | 30 | 34 | ||
Leasehold improvements | |||||
Property and Equipment | |||||
Property and equipment, gross | $ 185 | $ 178 | $ 26 |
Composition of Certain Financ_5
Composition of Certain Financial Statement Items - Accrued Expenses (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Composition of Certain Financial Statement Items | |||
Payroll and commissions payable | $ 3,619 | $ 2,871 | $ 1,861 |
Vacation | 946 | 723 | 564 |
Other accrued expenses | 397 | 438 | 279 |
Total accrued expenses | $ 4,962 | $ 4,032 | $ 2,704 |
Long-Term Debt (Details)
Long-Term Debt (Details) - USD ($) $ / shares in Units, $ in Thousands | Feb. 07, 2018 | Feb. 28, 2017 | Aug. 31, 2015 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2018 |
Credit Facility | |||||||
Outstanding credit facility amount | $ 16,500 | ||||||
Debt issuance costs | $ 72 | $ 0 | $ 0 | $ 72 | |||
Expected future principal payments | |||||||
2,018 | 0 | ||||||
2,019 | 4,583 | $ 0 | |||||
2,020 | 5,500 | 10,208 | |||||
2,021 | 5,500 | 12,250 | |||||
2,022 | 917 | 2,042 | |||||
Total expected future principal payments | $ 16,500 | $ 24,500 | |||||
Term A loan facility | |||||||
Credit Facility | |||||||
Maximum borrowing amount under credit facility | 15,500 | ||||||
Outstanding credit facility amount | $ 15,500 | ||||||
Fixed interest rate on credit facility (as a percent) | 7.95% | ||||||
Variable interest rate on credit facility (as a percent) | 6.90% | ||||||
Additional borrowing amount under credit facility | $ 1,000 | ||||||
Net proceeds from credit facility | $ 500 | ||||||
Term A loan facility | Prior to February 24, 2018/Prior to February 7, 2019 | |||||||
Credit Facility | |||||||
Prepayment fee (in percentage) | 2.50% | ||||||
Term A loan facility | On or after February 24, 2018 but prior to February 24, 2019/On or after February 7, 2019 but prior to February 7, 2020 | |||||||
Credit Facility | |||||||
Prepayment fee (in percentage) | 1.50% | ||||||
Term A loan facility | On or after February 24, 2019/On or after February 7, 2020 | |||||||
Credit Facility | |||||||
Prepayment fee (in percentage) | 1.00% | ||||||
Original credit facility | |||||||
Credit Facility | |||||||
Outstanding credit facility amount | $ 12,000 | ||||||
Term B loan facility | |||||||
Credit Facility | |||||||
Outstanding credit facility amount | $ 24,500 | $ 9,000 | |||||
Fixed interest rate on credit facility (as a percent) | 7.95% | 7.95% | |||||
Additional borrowing amount under credit facility | $ 8,000 | ||||||
Net proceeds from credit facility | $ 8,000 | ||||||
Trailing period revenue | 12 months | 12 months | |||||
Minimum amount of revenue for interest only period | $ 25,000 | $ 25,000 | |||||
Final payment fee (in percentage) | 5.00% | ||||||
Increase in interest rate in default (in percentage) | 5.00% | 5.00% | |||||
Term B loan facility | LIBOR | |||||||
Credit Facility | |||||||
Variable interest rate on credit facility (as a percent) | 6.90% | ||||||
Term B loan facility | Minimum | |||||||
Credit Facility | |||||||
Outstanding credit facility amount | $ 3,500 | ||||||
Term B loan facility | Maximum | |||||||
Credit Facility | |||||||
Outstanding credit facility amount | $ 10,000 | ||||||
Term B loan facility | Prior to February 24, 2018/Prior to February 7, 2019 | |||||||
Credit Facility | |||||||
Prepayment fee (in percentage) | 2.50% | ||||||
Term B loan facility | On or after February 24, 2018 but prior to February 24, 2019/On or after February 7, 2019 but prior to February 7, 2020 | |||||||
Credit Facility | |||||||
Prepayment fee (in percentage) | 1.50% | ||||||
Term B loan facility | On or after February 24, 2019/On or after February 7, 2020 | |||||||
Credit Facility | |||||||
Prepayment fee (in percentage) | 1.00% | ||||||
Series F convertible preferred stock | |||||||
Credit Facility | |||||||
Aggregate number of shares called by warrants | 233,577 | 29,197 | |||||
Period of warrants (in years) | 10 years | 10 years | |||||
Exercise Price | $ 1.37 | $ 1.37 | $ 1.37 | $ 1.37 |
Commitments - Operating Lease (
Commitments - Operating Lease (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Future minimum annual operating lease payments | |||||
2,018 | $ 190 | ||||
2,019 | $ 1,043 | 48 | |||
Total future operating lease payments | 2,043 | 238 | |||
Rent expense | |||||
Rent expense | $ 100 | $ 100 | $ 184 | $ 127 | $ 123 |
Commitments - Purchase Commitme
Commitments - Purchase Commitments (Details) - USD ($) $ in Millions | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Purchase Commitments | |||
Commitments to suppliers for inventory purchases | $ 16.2 | $ 9 | $ 6.1 |
Medtronic | |||
Purchase Commitments | |||
Commitments to suppliers for inventory purchases | $ 0.1 | $ 0.4 | $ 0.6 |
Stockholders' (Deficit) Equity
Stockholders' (Deficit) Equity - Authorized Shares (Details) - $ / shares | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Stockholders' Equity Note [Abstract] | |||
Total shares authorized | 210,000,000 | 186,894,620 | |
Common stock, authorized shares | 200,000,000 | 110,000,000 | 85,000,000 |
Preferred shares, authorized (in shares) | 10,000,000 | 76,894,620 | 58,354,472 |
Common stock, par value (in dollars per share) | $ 0.001 | $ 0.001 | $ 0.001 |
Preferred stock, par value (in dollars per share) | $ 0.001 | $ 0.001 | $ 0.001 |
Stockholders' (Deficit) Equit_2
Stockholders' (Deficit) Equity - Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands | 1 Months Ended | 12 Months Ended | ||||
Feb. 28, 2017 | Oct. 31, 2016 | Mar. 31, 2014 | Dec. 31, 2017 | Sep. 30, 2018 | Dec. 31, 2016 | |
Class of Stock [Line Items] | ||||||
Shares Authorized (in shares) | 76,894,620 | 10,000,000 | 58,354,472 | |||
Shares Issued (in shares) | 76,235,050 | 0 | 57,986,873 | |||
Shares Outstanding (in shares) | 76,235,050 | 0 | 57,986,873 | |||
Carrying Value | $ 119,106 | $ 0 | $ 94,138 | |||
Convertible Preferred Stock | ||||||
Class of Stock [Line Items] | ||||||
Shares Authorized (in shares) | 76,894,620 | 58,354,472 | ||||
Shares Issued (in shares) | 76,235,050 | 57,986,873 | ||||
Shares Outstanding (in shares) | 76,235,050 | 57,986,873 | ||||
Carrying Value | $ 119,106 | $ 94,138 | ||||
Series A convertible preferred stock | ||||||
Class of Stock [Line Items] | ||||||
Shares Authorized (in shares) | 5,375,507 | 5,375,507 | ||||
Shares Issued (in shares) | 5,375,507 | 5,375,507 | ||||
Shares Outstanding (in shares) | 5,375,507 | 5,375,507 | ||||
Carrying Value | $ 5,037 | $ 5,037 | ||||
Liquidation Preference per Share | $ 1 | |||||
8% Dividend per Share | 0.08 | |||||
Conversion Price per Share | 6.65 | |||||
Shares issue price (in dollars per share) | $ 1 | |||||
Number of common shares called by each convertible preferred share | 0.1504 | |||||
Series B convertible preferred stock | ||||||
Class of Stock [Line Items] | ||||||
Shares Authorized (in shares) | 8,706,909 | 8,706,909 | ||||
Shares Issued (in shares) | 8,706,909 | 8,706,909 | ||||
Shares Outstanding (in shares) | 8,706,909 | 8,706,909 | ||||
Carrying Value | $ 15,913 | $ 15,913 | ||||
Liquidation Preference per Share | $ 1.84 | |||||
8% Dividend per Share | 0.15 | |||||
Conversion Price per Share | 9.91 | |||||
Shares issue price (in dollars per share) | $ 1.84 | |||||
Number of common shares called by each convertible preferred share | 0.1855 | |||||
Series C convertible preferred stock | ||||||
Class of Stock [Line Items] | ||||||
Shares Authorized (in shares) | 14,091,589 | 14,091,589 | ||||
Shares Issued (in shares) | 13,829,906 | 13,829,906 | ||||
Shares Outstanding (in shares) | 13,829,906 | 13,829,906 | ||||
Carrying Value | $ 14,949 | $ 14,949 | ||||
Liquidation Preference per Share | $ 1.07 | |||||
8% Dividend per Share | 0.09 | |||||
Conversion Price per Share | 7.12 | |||||
Shares issue price (in dollars per share) | $ 1.07 | |||||
Number of common shares called by each convertible preferred share | 0.1504 | |||||
Series D convertible preferred stock | ||||||
Class of Stock [Line Items] | ||||||
Shares Authorized (in shares) | 5,683,292 | 5,683,292 | ||||
Shares Issued (in shares) | 5,683,292 | 5,683,292 | ||||
Shares Outstanding (in shares) | 5,683,292 | 5,683,292 | ||||
Carrying Value | $ 6,043 | $ 6,043 | ||||
Liquidation Preference per Share | $ 1.07 | |||||
8% Dividend per Share | 0.09 | |||||
Conversion Price per Share | 7.12 | |||||
Shares issue price (in dollars per share) | $ 1.07 | |||||
Number of common shares called by each convertible preferred share | 0.1504 | |||||
Series E convertible preferred stock | ||||||
Class of Stock [Line Items] | ||||||
Shares Authorized (in shares) | 15,373,091 | 15,373,091 | ||||
Shares Issued (in shares) | 15,267,175 | 15,267,175 | ||||
Shares Outstanding (in shares) | 15,267,175 | 15,267,175 | ||||
Carrying Value | $ 39,848 | $ 39,848 | ||||
Liquidation Preference per Share | $ 2.62 | |||||
8% Dividend per Share | 0.21 | |||||
Conversion Price per Share | $ 15.16 | |||||
Net proceeds from issuance of convertible preferred stock | $ 39,800 | |||||
Shares issued during the period | 15,267,175 | |||||
Shares issue price (in dollars per share) | $ 2.62 | |||||
Number of common shares called by each convertible preferred share | 0.1728 | |||||
Series F convertible preferred stock | ||||||
Class of Stock [Line Items] | ||||||
Shares Authorized (in shares) | 27,664,232 | 9,124,084 | ||||
Shares Issued (in shares) | 27,372,261 | 9,124,084 | ||||
Shares Outstanding (in shares) | 27,372,261 | 9,124,084 | ||||
Carrying Value | $ 37,316 | $ 12,348 | ||||
Liquidation Preference per Share | $ 1.37 | |||||
8% Dividend per Share | 0.11 | |||||
Conversion Price per Share | $ 9.11 | |||||
Net proceeds from issuance of convertible preferred stock | $ 25,000 | $ 12,300 | ||||
Shares issued during the period | 18,248,177 | 9,124,084 | ||||
Shares issue price (in dollars per share) | $ 1.37 | $ 1.37 | ||||
Number of common shares called by each convertible preferred share | 0.1504 |
Stockholders' (Deficit) Equit_3
Stockholders' (Deficit) Equity - Preferred Stock Warrants (Details) - USD ($) $ / shares in Units, $ in Thousands | Feb. 24, 2017 | Aug. 07, 2015 | Aug. 05, 2013 | Nov. 16, 2012 | Jun. 30, 2014 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2012 | Sep. 30, 2018 | May 07, 2018 | Feb. 07, 2018 | Feb. 28, 2017 | Jun. 27, 2014 |
Preferred Stock Warrants | ||||||||||||||
Proceeds from the exercise of preferred stock warrants | $ 0 | $ 277 | $ 0 | |||||||||||
Convertible Preferred Stock | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Warrants Outstanding | 396,795 | 367,598 | 630,372 | |||||||||||
Fair Value | $ 157 | $ 53 | $ 855 | |||||||||||
Series C convertible preferred stock | Warrants Issued on August 5, 2013 | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Warrants issued | 74,768 | |||||||||||||
Term of warrants | 10 years | |||||||||||||
Value of each warrant (in dollars per warrant) | $ 0.525 | |||||||||||||
Exercise Price | $ 1.07 | $ 1.07 | $ 1.07 | $ 1.07 | ||||||||||
Warrants Outstanding | 74,768 | 74,768 | 74,768 | |||||||||||
Initial Value | $ 39 | $ 39 | ||||||||||||
Fair Value | $ 33 | $ 11 | $ 80 | |||||||||||
Series C convertible preferred stock | Warrants Issued on November 16, 2012 | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Exercise Price | $ 1.07 | $ 1.07 | $ 1.07 | |||||||||||
Warrants Outstanding | 186,916 | 186,916 | 186,916 | |||||||||||
Initial Value | $ 96 | $ 96 | ||||||||||||
Fair Value | $ 82 | $ 28 | $ 200 | |||||||||||
Series C convertible preferred stock | Five Year Warrants Issued in November 2012 | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Warrants issued | 278,506 | |||||||||||||
Term of warrants | 5 years | |||||||||||||
Value of each warrant (in dollars per warrant) | $ 0.34 | |||||||||||||
Aggregate number of shares called by warrants | 258,880 | |||||||||||||
Proceeds from the exercise of preferred stock warrants | $ 277 | |||||||||||||
Exercise Price | $ 1.07 | |||||||||||||
Warrants Outstanding | 258,880 | |||||||||||||
Initial Value | $ 94 | |||||||||||||
Series C convertible preferred stock | Ten Year Warrants Issued in November 2012 | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Warrants issued | 186,916 | |||||||||||||
Term of warrants | 10 years | |||||||||||||
Value of each warrant (in dollars per warrant) | $ 0.515 | |||||||||||||
Exercise Price | $ 1.07 | |||||||||||||
Initial Value | $ 96 | |||||||||||||
Series E convertible preferred stock | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Warrants issued | 76,334 | |||||||||||||
Term of warrants | 10 years | |||||||||||||
Value of each warrant (in dollars per warrant) | $ 1.11 | |||||||||||||
Exercise Price | $ 2.62 | |||||||||||||
Initial Value | $ 85 | |||||||||||||
Series E convertible preferred stock | Warrants Issued on August 7, 2015 | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Warrants issued | 29,580 | |||||||||||||
Term of warrants | 10 years | |||||||||||||
Value of each warrant (in dollars per warrant) | $ 1.13 | |||||||||||||
Exercise Price | $ 2.62 | $ 2.62 | $ 2.62 | $ 2.62 | ||||||||||
Warrants Outstanding | 29,580 | 29,580 | 29,580 | |||||||||||
Initial Value | $ 33 | $ 33 | ||||||||||||
Fair Value | $ 8 | $ 4 | $ 41 | |||||||||||
Series E convertible preferred stock | Warrants Issued on June 27, 2014 | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Exercise Price | $ 2.62 | $ 2.62 | $ 2.62 | |||||||||||
Warrants Outstanding | 76,334 | 76,334 | 76,334 | |||||||||||
Initial Value | $ 85 | $ 85 | ||||||||||||
Fair Value | $ 21 | $ 10 | $ 174 | |||||||||||
Series F convertible preferred stock | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Aggregate number of shares called by warrants | 233,577 | 29,197 | ||||||||||||
Exercise Price | $ 1.37 | $ 1.37 | $ 1.37 | $ 1.37 | ||||||||||
Adjusted warrants due to dilutive issuance | 56,569 | 56,569 | ||||||||||||
Series F convertible preferred stock | Warrants Issued on February 24, 2017 | ||||||||||||||
Preferred Stock Warrants | ||||||||||||||
Warrants issued | 29,197 | |||||||||||||
Term of warrants | 10 years | |||||||||||||
Value of each warrant (in dollars per warrant) | $ 0.13 | |||||||||||||
Exercise Price | $ 1.37 | $ 1.37 | $ 1.37 | |||||||||||
Warrants Outstanding | 29,197 | 29,197 | ||||||||||||
Initial Value | $ 4 | |||||||||||||
Fair Value | $ 13 | $ 40 |
Stock Options - 2007 Plan (Deta
Stock Options - 2007 Plan (Details) - $ / shares | 9 Months Ended | 12 Months Ended | ||
Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Stock Options | ||||
Fixed exercise price of options, minimum | $ 2.80 | $ 0.94 | ||
Fixed exercise price of options, maximum | 54.99 | 6.65 | ||
Options granted exercise prices (in dollars per share) | $ 15.04 | $ 0.94 | $ 1.65 | $ 2.07 |
Options | ||||
Stock Options | ||||
Service period | 4 years | 4 years | ||
Contractual life of stock options (in years) | 10 years | 10 years | ||
Options | Vesting after first year of service | ||||
Stock Options | ||||
Percentage of shares to vest | 25.00% | 25.00% | ||
Options | Vesting in years two through four | ||||
Stock Options | ||||
Vesting period | 36 months | 36 months | ||
Stock Incentive Plan 2007 | ||||
Stock Options | ||||
Number of shares reserved for issuance | 2,945,384 |
Stock Options - Stock Option Ac
Stock Options - Stock Option Activity (Details) - $ / shares | Dec. 31, 2017 | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 |
Options | |||||
Outstanding at beginning of the year (in shares) | 2,071,616 | 1,497,511 | 1,541,163 | 1,534,672 | |
Granted (in shares) | 385,056 | 721,763 | 120,277 | 49,235 | |
Exercised (in shares) | (227,114) | (127,122) | (109,079) | (21,545) | |
Forfeited (in shares) | (31,428) | (20,536) | (54,850) | (21,199) | |
Outstanding at ending of the year (in shares) | 2,071,616 | 2,198,130 | 2,071,616 | 1,497,511 | 1,541,163 |
Exercisable (in shares) | 1,236,255 | 1,307,821 | 1,236,255 | ||
Weighted Average Exercise Price | |||||
Outstanding, beginning of the period (in dollars per share) | $ 1.47 | $ 1.76 | $ 1.77 | $ 1.77 | |
Granted (in dollars per share) | 15.04 | 0.94 | 1.65 | 2.07 | |
Exercised (in dollars per share) | 1.90 | 1.85 | 1.74 | 1.96 | |
Forfeited (in dollars per share) | 1.05 | 1.88 | 1.87 | 1.15 | |
Outstanding, end of the period (in dollars per share) | $ 1.47 | 3.80 | 1.47 | $ 1.76 | $ 1.77 |
Exercisable (in dollars per share) | $ 1.75 | $ 1.58 | $ 1.75 | ||
Weighted average remaining contractual term | |||||
Outstanding (in years) | 5 years 10 months 24 days | 6 years 10 months | 5 years 10 months 24 days | 5 years 9 months 18 days | 6 years 7 months 6 days |
Stock Options - Stock compensat
Stock Options - Stock compensation (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Stock Options | |||||
Total stock compensation | $ 696 | $ 189 | $ 243 | $ 248 | $ 305 |
Unearned stock compensation | $ 2,400 | $ 318,000 | |||
Weighted average recognition period | 2 years 7 months 12 days | 3 years | |||
General and administrative | |||||
Stock Options | |||||
Total stock compensation | $ 592 | 89 | $ 116 | 108 | 147 |
Sales and marketing | |||||
Stock Options | |||||
Total stock compensation | 88 | 73 | 84 | 90 | 99 |
Research and development | |||||
Stock Options | |||||
Total stock compensation | $ 16 | $ 27 | $ 43 | $ 50 | $ 59 |
Stock Options - Weighted averag
Stock Options - Weighted average assumptions used to calculate fair value of options (Details) - $ / shares | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Weighted average assumptions | |||||
Dividend yield | 0.00% | 0.00% | |||
Options | |||||
Weighted average assumptions | |||||
Dividend yield | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% |
Weighted average fair value | $ 7.43 | $ 0.40 | $ 0.40 | $ 0.47 | $ 0.86 |
Options | Minimum | |||||
Weighted average assumptions | |||||
Expected life (years) | 5 years 6 months | 5 years 9 months | 6 years 2 months 12 days | ||
Expected volatility | 37.50% | 39.90% | 40.60% | ||
Risk-free interest rate | 2.38% | 1.88% | 1.88% | 1.27% | 1.65% |
Options | Maximum | |||||
Weighted average assumptions | |||||
Expected life (years) | 6 years 3 months | 6 years 3 months | 6 years 2 months 12 days | 6 years 2 months 12 days | |
Expected volatility | 49.80% | 41.50% | 39.10% | 38.60% | |
Risk-free interest rate | 3.01% | 2.32% | 2.32% | 2.25% | 2.14% |
Related-Party Transactions (Det
Related-Party Transactions (Details) $ in Thousands | 4 Months Ended | 9 Months Ended | 12 Months Ended | |||||
May 07, 2018member | Sep. 30, 2018USD ($)member | Sep. 30, 2017USD ($) | Dec. 31, 2017USD ($)personitem | Dec. 31, 2016USD ($) | Dec. 31, 2015USD ($) | May 31, 2016item | May 31, 2016member | |
Development Agreement | ||||||||
Inventory purchases | $ 305 | $ 829 | ||||||
Medtronic | ||||||||
Board of Directors' Appointment | ||||||||
Number of person allowed for member of entities Board of Directors | 1 | 1 | ||||||
Number of voting member before the Series F Preferred Stock purchase agreement | 1 | 1 | ||||||
Number of non-voting member before the Series F Preferred Stock purchase agreement | 2 | 2 | ||||||
Supply Agreement | ||||||||
Number of buy right of inventory upon termination of supply agreement | 1 | 1 | ||||||
Development Agreement | ||||||||
Inventory purchases | $ 1,120 | $ 848 | $ 834 | |||||
Research and development expenses | 0 | 0 | 98 | |||||
Transactions with related party | $ 1,120 | $ 848 | $ 932 | |||||
Right-of-First-Offer of the company | ||||||||
Period to negotiate exclusively with Medtronic on possible sale of business prior to negotiating with third party | 90 days | 90 days |
Income Taxes - Components of pr
Income Taxes - Components of provision for income taxes (Details) - USD ($) $ in Millions | Jan. 01, 2018 | Dec. 22, 2017 | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 |
Components of the Company's provision for income taxes | ||||||
Tax at federal statutory rate (as a percent) | 21.00% | 35.00% | 35.00% | 35.00% | ||
State, net of federal benefit (as a percent) | 3.00% | 2.80% | 2.40% | |||
Permanent items (as a percent) | (1.10%) | (0.50%) | (0.80%) | |||
Research and development (R&D) tax credit (as a percent) | 1.20% | 1.30% | 1.40% | |||
Federal tax rate change (as a percent) | (92.60%) | 0.00% | 0.00% | |||
Other (as a percent) | 1.10% | 7.10% | 4.50% | |||
Change in valuation allowance (as a percent) | 53.40% | (45.70%) | (42.50%) | |||
Total | 0.00% | 0.00% | 0.00% | |||
Income tax expense on re-measurement of deferred tax assets and liabilities, provisional amount | $ 16.2 | |||||
Forecast | ||||||
Components of the Company's provision for income taxes | ||||||
Tax at federal statutory rate (as a percent) | 21.00% |
Income Taxes - Deferred tax ass
Income Taxes - Deferred tax assets (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 |
Deferred tax assets: | |||
Net operating losses | $ 27,827 | $ 36,626 | $ 28,385 |
R&D tax credits | 1,368 | 1,093 | 956 |
R&D expenditures, capitalized for tax | 2,146 | 2,682 | 2,515 |
Accruals and other | 753 | 1,065 | 1,165 |
Deferred tax assets, Gross | 32,094 | 41,466 | 33,020 |
Deferred tax liabilities: | |||
Depreciation and amortization | 4 | (4) | (28) |
Net deferred tax assets | 32,098 | 41,462 | 32,992 |
Valuation allowance | (32,098) | (41,462) | (32,992) |
Net deferred tax assets, less valuation allowance | $ 0 | $ 0 | $ 0 |
Income Taxes - Operating loss (
Income Taxes - Operating loss (Details) - USD ($) $ in Millions | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Operating Loss Carryforwards [Line Items] | |||
Valuation allowance increase (decrease) | $ (9.4) | $ 8.5 | $ 9.1 |
Federal | |||
Operating Loss Carryforwards [Line Items] | |||
Net operating loss carryforwards | 110.9 | ||
State | |||
Operating Loss Carryforwards [Line Items] | |||
Net operating loss carryforwards | 65.9 | ||
R&D credit | |||
Operating Loss Carryforwards [Line Items] | |||
Credit carryforwards | $ 1.4 |
Segment Reporting and Signifi_3
Segment Reporting and Significant Customers (Details) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018USD ($)segment | Sep. 30, 2017USD ($) | Dec. 31, 2017USD ($)segment | Dec. 31, 2016USD ($) | Dec. 31, 2015USD ($) | |
Segment Reporting and Significant Customers | |||||
Number of reporting segment | segment | 1 | 1 | |||
Total revenue | $ 34,034 | $ 18,610 | $ 28,567 | $ 16,427 | $ 8,012 |
United States | |||||
Segment Reporting and Significant Customers | |||||
Total revenue | 29,580 | 15,922 | 24,293 | 13,789 | 6,132 |
Europe | |||||
Segment Reporting and Significant Customers | |||||
Total revenue | $ 4,454 | $ 2,688 | $ 4,274 | $ 2,638 | $ 1,880 |
Loss Per Share (Details)
Loss Per Share (Details) - shares | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Loss Per Share | |||||
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding | 2,279,014 | 14,252,134 | 14,607,106 | 11,259,726 | 9,904,353 |
Convertible Preferred Stock | |||||
Loss Per Share | |||||
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding | 0 | 12,111,706 | 12,111,706 | 9,367,628 | 7,995,592 |
Convertible preferred stock warrants | |||||
Loss Per Share | |||||
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding | 0 | 65,434 | 423,784 | 394,587 | 367,598 |
Common stock options | |||||
Loss Per Share | |||||
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding | 2,198,130 | 2,074,994 | 2,071,616 | 1,497,511 | 1,541,163 |
Subsequent Events (Details)
Subsequent Events (Details) $ / shares in Units, $ in Millions | Apr. 20, 2018 | Feb. 07, 2018USD ($)$ / sharesshares | Feb. 28, 2017USD ($)$ / sharesshares | Sep. 30, 2018$ / shares | Dec. 31, 2017$ / shares | Aug. 31, 2015 |
Subsequent Events | ||||||
Outstanding credit facility amount | $ 16.5 | |||||
Subsequent event | ||||||
Subsequent Events | ||||||
Reverse stock split ratio | 0.150 | |||||
Term B loan facility | ||||||
Subsequent Events | ||||||
Additional borrowing amount under credit facility | $ 8 | |||||
Net proceeds from credit facility | 8 | |||||
Outstanding credit facility amount | $ 24.5 | $ 9 | ||||
Fixed interest rate on credit facility (as a percent) | 7.95% | 7.95% | ||||
Trailing period revenue | 12 months | 12 months | ||||
Minimum amount of revenue for interest only period | $ 25 | $ 25 | ||||
Term B loan facility | LIBOR | ||||||
Subsequent Events | ||||||
Variable interest rate on credit facility (as a percent) | 6.90% | |||||
Term B loan facility | Subsequent event | ||||||
Subsequent Events | ||||||
Additional borrowing amount under credit facility | $ 8 | |||||
Net proceeds from credit facility | 8 | |||||
Outstanding credit facility amount | $ 24.5 | |||||
Fixed interest rate on credit facility (as a percent) | 7.95% | |||||
Trailing period revenue | 12 months | |||||
Minimum amount of revenue for interest only period | $ 25 | |||||
Term B loan facility | Subsequent event | LIBOR | ||||||
Subsequent Events | ||||||
Variable interest rate on credit facility (as a percent) | 6.90% | |||||
Series F convertible preferred stock | ||||||
Subsequent Events | ||||||
Aggregate number of shares called by warrants | shares | 233,577 | 29,197 | ||||
Period of warrants (in years) | 10 years | 10 years | ||||
Exercise Price | $ / shares | $ 1.37 | $ 1.37 | $ 1.37 | $ 1.37 | ||
Series F convertible preferred stock | Subsequent event | ||||||
Subsequent Events | ||||||
Aggregate number of shares called by warrants | shares | 233,577 | |||||
Period of warrants (in years) | 10 years | |||||
Exercise Price | $ / shares | $ 1.37 |
CONDENSED BALANCE SHEETS
CONDENSED BALANCE SHEETS - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 |
Current assets: | ||||||
Cash and cash equivalents | $ 26,312 | $ 8,955 | $ 14,540 | $ 6,685 | $ 12,126 | $ 8,274 |
Short-term investments | 94,114 | 7,188 | 0 | |||
Accounts receivable, net of allowances of $47 | 5,410 | 3,858 | 2,091 | |||
Inventories | 3,075 | 3,670 | 3,355 | |||
Prepaid expenses and other assets | 1,044 | 426 | 118 | |||
Total current assets | 129,955 | 24,097 | 12,249 | |||
Property and equipment, cost | 1,553 | 1,804 | 1,548 | |||
Less: accumulated depreciation | (788) | (810) | (681) | |||
Property and equipment, net | 765 | 994 | 867 | |||
Total assets | 130,720 | 25,091 | 13,116 | |||
Current liabilities: | ||||||
Accounts payable | 2,449 | 2,998 | 1,173 | |||
Accrued expenses | 4,962 | 4,032 | 2,704 | |||
Accrued interest | 184 | 117 | 103 | |||
Total current liabilities | 7,595 | 7,147 | 7,290 | |||
Notes payable | 24,814 | 16,460 | 12,381 | |||
Preferred stock warrants | 0 | 157 | 53 | |||
Total long-term liabilities | 24,814 | 16,617 | 12,434 | |||
Stockholders' equity | ||||||
Preferred Stock, $0.001 par value, 10,000,000 shares and 76,894,620 shares authorized at September 30, 2018 and December 31, 2017, respectively; none and 76,235,050 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively | 0 | 119,106 | 94,138 | |||
Common Stock, $0.001 par value per share; 200,000,000 shares and 110,000,000 shares authorized at September 30, 2018 and December 31, 2017, respectively; 21,391,590 and 1,272,360 issued and outstanding at September 30, 2018 and December 31, 2017, respectively | 21 | 1 | 1 | |||
Additional paid-in capital | 240,451 | 7,305 | 6,827 | |||
Accumulated other comprehensive loss | (26) | 0 | 0 | |||
Accumulated deficit | (142,135) | (125,085) | (107,574) | |||
Total stockholders' equity | 98,311 | 1,327 | (6,608) | $ (1,142) | $ 19,834 | |
Total liabilities and stockholders' equity | $ 130,720 | $ 25,091 | $ 13,116 |
CONDENSED BALANCE SHEETS (Paren
CONDENSED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Statement of Financial Position [Abstract] | |||
Accounts receivable, allowances | $ 47 | $ 47 | $ 44 |
Preferred shares, par value (in dollars per share) | $ 0.001 | $ 0.001 | $ 0.001 |
Preferred shares, authorized (in shares) | 10,000,000 | 76,894,620 | 58,354,472 |
Preferred shares, issued (in shares) | 0 | 76,235,050 | 57,986,873 |
Preferred shares, outstanding (in shares) | 0 | 76,235,050 | 57,986,873 |
Common stock, par value (in dollars per share) | $ 0.001 | $ 0.001 | $ 0.001 |
Common stock, authorized (in shares) | 200,000,000 | 110,000,000 | 85,000,000 |
Common stock, issued (in shares) | 21,391,590 | 1,272,360 | 1,145,238 |
Common stock, outstanding (in shares) | 21,391,590 | 1,272,360 | 1,145,238 |
CONDENSED STATEMENTS OF OPERATI
CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands | 9 Months Ended | |
Sep. 30, 2018 | Sep. 30, 2017 | |
Income Statement [Abstract] | ||
Revenue | $ 34,034 | $ 18,610 |
Cost of goods sold | 6,863 | 4,137 |
Gross profit | 27,171 | 14,473 |
Operating expenses: | ||
Selling and marketing | 31,913 | 19,566 |
Research and development | 5,236 | 4,512 |
General and administrative | 5,503 | 2,552 |
Total operating expenses | 42,652 | 26,630 |
Operating loss | (15,481) | (12,157) |
Other expense (income): | ||
Interest income | (1,049) | (119) |
Interest expense | 2,615 | 1,224 |
Other expense (income), net | 3 | (2) |
Total other expense | 1,569 | 1,103 |
Loss before income taxes | (17,050) | (13,260) |
Income taxes | 0 | 0 |
Net loss | (17,050) | (13,260) |
Unrealized loss on short-term investments | (26) | 0 |
Total comprehensive loss | $ (17,076) | $ (13,260) |
Net loss per share, basic and diluted (in dollars per share) | $ (1.40) | $ (11.45) |
Weighted average common shares used to compute net loss per share, basic and diluted (in shares) | 12,137,512 | 1,158,548 |
CONDENSED STATEMENTS OF CASH FL
CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands | 9 Months Ended | |
Sep. 30, 2018 | Sep. 30, 2017 | |
Operating activities | ||
Net loss | $ (17,050) | $ (13,260) |
Adjustments to reconcile net loss: | ||
Depreciation and amortization | 288 | 174 |
Accretion of debt discount | 456 | 231 |
Stock-based compensation expense | 696 | 189 |
Non-cash stock issuance for services rendered | 37 | 0 |
Change in the fair value of preferred stock warrants | 595 | 0 |
Changes in operating assets and liabilities: | ||
Accounts receivable | (1,552) | (1,105) |
Inventories | 595 | 312 |
Prepaid expenses and other assets | (618) | (93) |
Accounts payable | (549) | 445 |
Accrued expenses | 997 | 593 |
Net cash used in operating activities | (16,105) | (12,514) |
Investing activities | ||
Purchases of property and equipment | (59) | (350) |
Purchases of short-term investments | (98,936) | (4,802) |
Proceeds from sales or maturities of short-term investments | 11,984 | 0 |
Net cash used in investing activities | (87,011) | (5,152) |
Financing activities | ||
Proceeds from issuance of notes payable | 8,000 | 458 |
Proceeds from the exercise of stock options and warrants | 431 | 95 |
Proceeds from sale of common stock | 112,042 | 0 |
Proceeds from sale of preferred stock | 0 | 24,968 |
Net cash provided by financing activities | 120,473 | 25,521 |
Increase in cash and cash equivalents | 17,357 | 7,855 |
Cash and cash equivalents at beginning of period | 8,955 | 6,685 |
Cash and cash equivalents at end of period | 26,312 | 14,540 |
Supplemental cash flow information | ||
Cash paid for interest | 1,453 | 984 |
Issuance of preferred stock warrants | $ 103 | $ 4 |
Organization_2
Organization | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Organization, Consolidation and Presentation of Financial Statements [Abstract] | ||
Organization | Organization Description of Business Inspire Medical Systems, Inc. is a medical technology company focused on the development and commercialization of innovative and minimally invasive solutions for patients with obstructive sleep apnea ("OSA"). Our proprietary Inspire system is the first and only FDA-approved neurostimulation technology that provides a safe and effective treatment for moderate to severe obstructive sleep apnea. We have developed a novel, closed-loop solution that continuously monitors a patient's breathing and delivers mild hypoglossal nerve stimulation to maintain an open airway. Inspire therapy received premarket approval ("PMA") from the U.S. Food and Drug Administration ("FDA") in April 2014 and has been commercially available in certain European markets since November 2011. In June 2018, Japan's Ministry of Health, Labour and Welfare approved Inspire therapy to treat moderate to severe OSA, and we will now seek reimbursement coverage in Japan. | 1. Organization Description of Business Inspire Medical Systems, Inc. (the Company) is a medical technology company focused on the development and commercialization of innovative and minimally invasive solutions for patients with obstructive sleep apnea. The Company's proprietary Inspire system is the first and only FDA-approved neurostimulation technology that provides a safe and effective treatment for moderate to severe obstructive sleep apnea. The Company has developed a novel, closed-loop solution that continuously monitors a patient’s breathing and delivers mild hypoglossal nerve stimulation to maintain an open airway. Inspire therapy received premarket approval, or PMA, from the U.S. Food and Drug Administration, or FDA, in April 2014 and has been commercially available in certain European markets since November 2011. |
Summary of Significant Accou_11
Summary of Significant Accounting Policies | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Accounting Policies [Abstract] | ||
Summary of Significant Accounting Policies | Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed financial statements have been prepared without audit, pursuant to the rules and regulations of the SEC. The condensed financial statements may not include all disclosures required by U.S. GAAP; however, we believe that the disclosures are adequate to make the information presented not misleading. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and the notes thereto for the fiscal year ended December 31, 2017 included in our audited consolidated financial statements for the year ended December 31, 2017 and the notes thereto for the year ended December 31, 2017 included in our final prospectus that forms a part of our Registration Statement on Form S-1 (File No. 333-224176), filed with the Securities and Exchange Commission ("SEC") pursuant to Rule 424(b)(4) on May 4, 2018 (the "Prospectus"). The condensed balance sheet at December 31, 2017 was derived from the audited financial statements. In the opinion of management, all adjustments, consisting of only normal recurring adjustments that are necessary to present fairly the financial position, results of operations, and cash flows for the interim periods, have been made. The results of operations for the interim periods are not necessarily indicative of the operating results for the full fiscal year or any future periods. Reverse Stock Split In connection with our initial public offering of common stock ("IPO"), our board of directors and stockholders approved a 1-for-6.650 reverse stock split of our common stock. The reverse stock split became effective on April 20, 2018. The par value of the common stock was not adjusted as a result of the reverse stock split. Adjustments corresponding to the reverse stock split were made to the ratio at which the convertible preferred stock will convert into common stock immediately prior to the closing of the IPO. Accordingly, all share and per-share amounts for all periods presented in these financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect the reverse stock split and adjustment of the conversion ratio of the convertible preferred stock. Initial Public Offering On May 7, 2018, we completed our IPO by issuing 7,762,500 shares of common stock, at an offering price of $16.00 per share, for net proceeds of approximately $112.0 million after deducting underwriting discounts and commissions and offering expenses payable by us. In connection with the IPO, our outstanding shares of convertible preferred stock were automatically converted into an aggregate of 12,111,706 shares of common stock, and our outstanding warrants to purchase shares of convertible preferred stock were automatically converted into warrants to purchase up to an aggregate of 100,558 shares of common stock, resulting in the reclassification of the related redeemable convertible preferred stock warrant liability of $0.9 million to additional paid-in capital ("APIC"). Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. We use significant judgment when making estimates related to the allowance for doubtful accounts, inventory reserves and the valuations of our common stock, share-based awards, and certain of our previously outstanding preferred stock warrants. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. JOBS Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act"), we are eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. We have elected to take advantage of the extended transition period for adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. Cash and Cash Equivalents We consider all highly liquid securities, readily convertible to cash, that mature within 90 days or less from the date of purchase to be cash equivalents. The carrying amount reported in the balance sheets for cash is cost, which approximates fair value. Short-Term Investments At September 30, 2018 and December 31, 2017 , our short-term investments consisted of commercial paper, corporate bonds, and U.S. government securities which are classified as available-for-sale and had maturities less than one year. Short-term investments are reported at their estimated fair market value which approximates cost. Any unrealized gains and losses are reported in accumulated other comprehensive loss. We had less than $0.1 million and $0 accumulated other comprehensive loss balance at September 30, 2018 or December 31, 2017 , respectively. Any realized gains and losses are reported net in interest income or interest expense. For the nine months ended September 30, 2018 , we recognized $0.4 million of gains, net. Fair Value of Financial Instruments We measure certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents, short-term investments, and certain of our previously outstanding preferred stock warrants. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Observable inputs, such as quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Other inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs, including interest rate curves, foreign exchange rates, and credit ratings. Level 3—Unobservable inputs that are supported by little or no market activities, which would require us to develop our own assumptions. We use the methods and assumptions described below in determining the fair value of our financial instruments. Money market funds: Fair values of money market funds are based on quoted market prices in active markets. Commercial paper: Short-term, highly liquid investments are included as a Level 2 measurement in the tables below. Corporate bonds: Consists of notes, asset-backed securities and bonds with original maturities of less than one year and various yields. These are included as a Level 2 measurement in the tables below. U.S. government securities: Consists of U.S. Government treasury bills with original maturities of less than one year. These are included as a Level 1 measurement in the table below. The following tables sets forth by level within the fair value hierarchy our assets and liabilities that are reported at fair value as of September 30, 2018 and December 31, 2017 . As required by Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 820, Fair Value Measurement , assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of September 30, 2018 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 14,250 $ 14,250 $ — $ — Commercial paper 10,382 — 10,382 — Total cash equivalents 24,632 14,250 10,382 — Short-term investments: Commercial paper $ 47,631 $ — $ 47,631 $ — Corporate bonds 34,576 — 34,576 — U.S. government securities 11,907 11,907 — — Total short-term investments 94,114 11,907 82,207 — Total assets $ 118,746 $ 26,157 $ 92,589 $ — Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 $ — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 There were no transfers in and out of Level 1 and Level 2 fair value measurements during the periods ended September 30, 2018 and December 31, 2017 . The recurring Level 3 fair value measurements of our preferred stock warrant liabilities used the Black-Scholes option pricing model and value of the respective class of our convertible preferred stock (see Note 8 ), which was unobservable. All other assumptions included in the model are observable Level 1 inputs. The following table provides a reconciliation of the beginning and ending balances of our preferred stock warrant liabilities: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Balance at beginning of period $ — $ 57 $ 157 $ 53 Initial fair value of preferred stock warrants issued — — 103 4 Reclassified to equity — — (855 ) — Change in fair value of preferred stock warrants — — 595 — Balance at end of period $ — $ 57 $ — $ 57 Changes in the fair value of the preferred stock warrant liability were recorded in other expenses on the condensed statements of operations and comprehensive loss. In connection with the closing of the IPO in May 2018, warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock, resulting in the reclassification of the related convertible preferred stock warrant liability to APIC. Concentration of Credit Risk Financial instruments, which potentially subject us to concentrations of credit risk, consist principally of cash equivalents and accounts receivable. We believe that the credit risk in our accounts receivable is mitigated by our credit evaluation process, relatively short collection terms, and dispersion of our customer base. We generally do not require collateral, and losses on accounts receivable have historically been within management's expectations. Our investment policy limits investments to certain types of debt securities issued by the U.S. government and its agencies, corporations with investment-grade credit ratings, or commercial paper and money market funds issued by the highest quality financial and non-financial companies. We place restrictions on maturities and concentration by type and issuer. We are exposed to credit risk in the event of a default by the issuers of these securities to the extent recorded on the balance sheets. However, as of September 30, 2018 and December 31, 2017 , we limited our credit risk associated with cash equivalents by placing investments with banks we believe are highly creditworthy. Allowance for Doubtful Accounts We record an allowance for doubtful accounts for accounts receivable deemed uncollectible. We evaluate the collectability of our accounts receivable based on known collection risks and historical experience. In circumstances where we are aware of a specific customer's inability to meet its financial obligations to us (e.g., bankruptcy filings, substantial downgrading of credit ratings), we record a specific allowance for bad debts against amounts due to reduce the carrying amount of accounts receivable to the amount we reasonably believe will be collected. Inventories Inventories are valued at the lower of cost or net realizable value, computed on a first-in, first out basis. We regularly review inventory quantities on-hand for excess and obsolete inventory and, when circumstances indicate, incur charges to write down inventories to their net realizable value. Our review of inventory for excess and obsolete quantities is based primarily on the estimated forecast of future product demand, product life cycles, including expiration of inventory prior to sale, and introduction of new products. The reserve for excess and obsolete inventory was $0.8 million and $0.5 million as of September 30, 2018 and December 31, 2017 , respectively. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. Impairment of Long-lived Assets Long-lived assets consist primarily of property and equipment and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require that an asset be tested for possible impairment, we compare the undiscounted cash flows expected to be generated by the asset to the carrying amount of the asset. If the carrying amount of the asset is not recoverable on an undiscounted cash flow basis, we determine the fair value of the asset and recognize an impairment loss to the extent the carrying amount of the asset exceeds its fair value. We determine fair value using the income approach based on the present value of expected future cash flows or other appropriate measures of estimated fair value. Our cash flow assumptions consider historical and forecasted revenue and operating costs and other relevant factors. We did not record any impairment charges on long-lived assets during the nine months ended September 30, 2018 and 2017 . Revenue Recognition We recognize revenue when persuasive evidence of an arrangement exists, product shipment has occurred, or there are no further obligations yet to be performed, pricing is fixed or determinable, and collection is reasonably assured. We make reasonable assumptions regarding the future collectability of amounts receivable from customers to determine whether the revenue recognition criteria have been met. Taxes assessed by a governmental authority that are directly imposed on revenue-producing transactions between a seller and a customer are not recorded as revenue. In general, our standard terms and conditions of sale do not allow for product returns. Sales returns have been limited to damaged product and have not been material. We expense shipping and handling costs as incurred and include them in the cost of goods sold. In those cases where shipping and handling costs are billed to customers, we classify the amounts billed as a component of cost of goods sold. Cost of Goods Sold Cost of goods sold consists primarily of manufacturing overhead costs, material costs, and direct labor. Overhead costs include the cost of material procurement, inventory control, facilities, equipment, and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs. Research and Development Research and development expenses consist primarily of product development, clinical and regulatory affairs, consulting services, and other costs associated with products and technologies in development. These expenses include employee compensation, stock-based compensation, supplies, travel, and facility costs. Clinical expenses include clinical trial design, clinical site reimbursement, data management, travel expenses, and the cost of manufacturing products for clinical trials. Common Stock Valuation and Stock-Based Compensation We maintain an equity incentive plan to provide long-term incentives for employees, consultants, and members of the board of directors. The plan allows for the issuance of non-statutory and incentive stock options to employees and non-statutory stock options to consultants and non-employee directors. We recognize equity-based compensation expense for awards of equity instruments to employees and non-employees based on the grant date fair value of those awards in accordance with FASB ASC Topic 718, Stock Compensation ("ASC 718"). ASC 718 requires all equity-based compensation awards to employees and nonemployee directors, including grants of restricted shares and stock options, to be recognized as expense in the statements of operations and comprehensive loss based on their grant date fair values. We estimate the fair value of stock options using the Black-Scholes option pricing model. We use the value of our common stock to determine the fair value of restricted shares. We account for restricted stock and common stock options issued to nonemployees under FASB ASC Topic 505-50, Equity-Based Payments to Non-Employees . As such, the value of such options is periodically remeasured and income or expense is recognized over their vesting terms. Compensation cost related to awards with service-based vesting schedules is recognized using the straight-line method. We determine the fair value of the restricted stock and common stock granted to nonemployees as either the fair value of the consideration received or the fair value of the equity instruments issued. We have not granted any share-based awards to our consultants. The Black-Scholes option pricing model requires the input of certain subjective assumptions, including (i) the expected share price volatility, (ii) the expected term of the award, (iii) the risk-free interest rate and (iv) the expected dividend yield. Due to the lack of a public market for the trading of our common stock and a lack of company-specific historical and implied volatility data, we have based our estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The group of representative companies have characteristics similar to us, including stage of product development and focus on the life science industry. We use the simplified method, which is the average of the final vesting tranche date and the contractual term, to calculate the expected term for options granted to employees as we do not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. For options granted to non-employees, we utilize the contractual term of the arrangement as the basis for the expected term assumption. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. We use an assumed dividend yield of zero as we have never paid dividends and have no current plans to pay any dividends on our common stock. We expense the fair value of our equity-based compensation awards granted to employees on a straight-line basis over the associated service period, which is generally the period in which the related services are received. We measure equity-based compensation awards granted to nonemployees at fair value as the awards vest and recognize the resulting value as compensation expense at each financial reporting period. We account for award forfeitures as they occur. Advertising Expenses We expense the costs of advertising, including promotional expenses, as incurred. Advertising expenses were $2.0 million and $1.4 million during the three months ended September 30, 2018 and 2017 , respectively, and $5.8 million and $3.7 million during the nine months ended September 30, 2018 and 2017 , respectively. Income Taxes We account for income taxes using the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates that will be in effect when the differences are expected to reverse. Valuation allowances against deferred tax assets are established, when necessary, to reduce deferred tax assets to the amounts expected to be realized. As we have historically incurred operating losses, we have recorded a full valuation allowance against our net deferred tax assets, and there is no provision for income taxes. Our policy is to record interest and penalties expense related to uncertain tax positions as other expense in the statements of operations and comprehensive loss. Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on short-term investments classified as available-for-sale, if any. Accumulated other comprehensive loss is presented in the accompanying balance sheets as a component of stockholders' equity, if any. Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because we have reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, stock options and warrants were antidilutive in those periods. Recent Accounting Pronouncements We are an “emerging growth company” as defined by the JOBS Act. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act of 1933, as amended, (the "Securities Act"), for complying with new or revised accounting standards. Accordingly, an emerging growth company can selectively delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this exemption and, as a result, our financial statements may not be comparable to the financial statements of issuers that are required to comply with the effective dates for new or revised accounting standards that are applicable to public companies. Section 107 of the JOBS Act provides that we can elect to opt out of the extended transition period at any time, which election is irrevocable. In May 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers . The new section will replace Section 605, Revenue Recognition , and creates modifications to various other revenue accounting standards for specialized transactions and industries. The section is intended to conform revenue accounting principles with the concurrently issued International Financial Reporting Standards to reconcile previously differing treatment between U.S. practices and those of the rest of the world and to enhance disclosures related to disaggregated revenue information. The updated guidance is effective for interim and annual reporting periods beginning on or after December 15, 2018 for private companies and, therefore, us due to the JOBS Act exemption described above. We have commenced project planning for our implementation, which has included engaging an accounting firm to assist us. We have not yet made a determination on our transition method, nor have we determined whether this standard will have a material impact on our financial statements. We plan to complete our assessment of the impact of this standard during the fourth quarter of 2018. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes ("ASU 2015-17"). ASU 2015-17 is intended to reduce complexity surrounding the presentation of deferred taxes within the balance sheet. Specifically, ASU 2015-17 requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non-current on the balance sheet, effectively eliminating the requirement to allocate deferred taxes between current and non-current amounts. The new guidance does not permit companies to offset deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. This guidance was effective January 1, 2018 and did not significantly impact our financial statements and related disclosures. In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842), which supersedes the existing guidance for lease accounting, Leases (Topic 840). ASU 2016-02 requires lessees to recognize a lease liability and a right-of-use asset for all leases. Lessor accounting remains largely unchanged. The amendments in this ASU are effective for interim and annual periods beginning after December 15, 2019 for private companies; and, therefore, us due to the JOBS Act exemption described above. Early adoption is permitted for all entities. ASU 2016-02 requires a modified retrospective approach for all leases existing at, or entered into after, the date of initial adoption, with an option to elect to use certain transition relief. We plan to further evaluate the anticipated impact of the adoption of this ASU on our financial statements in future periods. In March 2016, the FASB issued No. 2016-9, Improvements to Employee Share-Based Payment Accounting ("ASU 2016-9"), which changes how companies will account for certain aspects of share-based payments to employees. As part of the new guidance, entities will be required to record the impact of income taxes arising from share-based compensation when awards vest or are settled within earnings as part of income tax expense rather than recorded as part of APIC and will eliminate the requirement that excess tax benefits be realized prior to recognition. Additionally, the guidance requires entities to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. Additionally, companies will be required to make an accounting policy election at the time of adoption of the new guidance to either account for forfeitures of share-based awards in a manner similar to today's requirements (i.e., estimating the number of awards expected to be forfeited at the grant date and adjusting the estimate when awards are actually forfeited), or recognizing forfeitures as they occur with no estimate of forfeitures determined at the grant date. Companies will also be able to set a maximum statutory tax rate as it pertains to share-based awards it net settles on behalf of its employees. This will provide companies a greater ability to retain equity-award accounting treatment. Entities will apply the provisions of ASU 2016-9 using a modified retrospective transition approach, with a cumulative-effect adjustment booked to retained earnings as of the beginning of the period of adoption. This guidance was effective for us on January 1, 2018 and did not significantly impact our financial statements and related disclosures. We have reviewed and considered all other recent accounting pronouncements and believe there are none that could potentially have a material impact on our business practices, financial condition, results of operations, or disclosures. | 2. Summary of Significant Accounting Policies Basis of Presentation The financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP). Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its allowance for doubtful accounts, inventory reserves and the valuations of its common stock, share‑based awards, and certain of its outstanding preferred stock warrants. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. JOBS Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act, the Company is eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. The Company has elected to take advantage of the extended transition period for adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. Cash and Cash Equivalents The Company considers all highly liquid securities, readily convertible to cash, that mature within 90 days or less from the date of purchase to be cash equivalents. The carrying amount reported in the balance sheets for cash is cost, which approximates fair value. Short‑term Investments The Company had no short-term investments at December 31, 2016. At December 31, 2017, the Company's short-term investments consisted of commercial paper and corporate bonds which are classified as available-for-sale and had maturities less than one year. Short-term investments are reported at their estimated fair market value which approximates cost at December 31, 2017. Any with unrealized gains and losses are reported in accumulated other comprehensive loss. Fair Value of Financial Instruments The Company measures certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents and certain of its outstanding preferred stock warrants. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market‑based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three‑tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Observable inputs, such as quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Other inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model‑based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market‑based observable inputs, including interest rate curves, foreign exchange rates, and credit ratings. Level 3—Unobservable inputs that are supported by little or no market activities, which would require the Company to develop its own assumptions. The Company uses the methods and assumptions described below in determining the fair value of its financial instruments. Money market funds: Fair values of money market funds are based on quoted market prices in active markets. Commercial paper: Short‑term, highly liquid investments are included as a Level 2 measurement in the tables below. Corporate bonds: Consists of U.S. Government treasury bills, notes, and bonds with original maturities of less than one year and various yields. These are included as a Level 2 measurement in the tables below. The following tables sets forth by level within the fair value hierarchy the Company’s assets and liabilities that are reported at fair value as of December 31, 2016 and 2017. As required by Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 820, Fair Value Measurement , assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of December 31, 2016 Estimated Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ $ $ — $ — Liabilities Preferred stock warrants $ $ — $ — $ Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 There were no transfers in and out of Level 1 and Level 2 fair value measurements during the years ended December 31, 2016 and 2017. The recurring Level 3 fair value measurements of the Company's preferred stock warrant liabilities use the Black-Scholes option pricing model and value of the respective class of the Company's convertible preferred stock (see Note 7), which is unobservable. All other assumptions included in the model are observable Level 1 inputs. The following table provides a reconciliation of the beginning and ending balances of the Company's preferred stock warrant liabilities: Balance as of December 31, 2014 $ Initial fair value of preferred stock warrants issued 33 Change in fair value of preferred stock warrants 12 Balance as of December 31, 2015 248 Change in fair value of preferred stock warrants (195) Balance as of December 31, 2016 53 Initial fair value of preferred stock warrants issued Change in fair value of preferred stock warrants Balance as of December 31, 2017 $ 157 Changes in the fair value of the preferred stock warrant liability are recorded in other expenses on the statements of operations and comprehensive loss. Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentrations of credit risk, consist principally of cash equivalents and accounts receivable. The Company believes that the credit risk in its accounts receivable is mitigated by its credit evaluation process, relatively short collection terms, and dispersion of its customer base. The Company generally does not require collateral, and losses on accounts receivable have historically been within management’s expectations. The Company’s investment policy limits investments to certain types of debt securities issued by the U.S. government and its agencies, corporations with investment‑grade credit ratings, or commercial paper and money market funds issued by the highest quality financial and non‑financial companies. The Company places restrictions on maturities and concentration by type and issuer. The Company is exposed to credit risk in the event of a default by the issuers of these securities to the extent recorded on the balance sheets. However, as of December 31, 2016 and 2017, the Company has limited its credit risk associated with its cash equivalents by placing its investments with banks it believes are highly creditworthy. Allowance for Doubtful Accounts The Company records an allowance for doubtful accounts for accounts receivable deemed uncollectible. The Company evaluates the collectability of its accounts receivable based on known collection risks and historical experience. In circumstances where the Company is aware of a specific customer’s inability to meet its financial obligations to the Company (e.g., bankruptcy filings, substantial downgrading of credit ratings), the Company records a specific allowance for bad debts against amounts due to reduce the carrying amount of accounts receivable to the amount it reasonably believes will be collected. Inventories Inventories are valued at the lower of cost or net realizable value, computed on a first-in, first out basis. The Company regularly reviews inventory quantities on-hand for excess and obsolete inventory and, when circumstances indicate, incurs charges to write down inventories to their net realizable value. The Company's review of inventory for excess and obsolete quantities is based primarily on the estimated forecast of future product demand, product life cycles, including expiration of inventory prior to sale, and introduction of new products. The reserve for excess and obsolete inventory was $191 and $518 as of December 31, 2016 and 2017, respectively. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight‑line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. Impairment of Long‑lived Assets Long‑lived assets consist primarily of property and equipment and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require that an asset be tested for possible impairment, the Company compares the undiscounted cash flows expected to be generated by the asset to the carrying amount of the asset. If the carrying amount of the asset is not recoverable on an undiscounted cash flow basis, the Company determines the fair value of the asset and recognizes an impairment loss to the extent the carrying amount of the asset exceeds its fair value. The Company determines fair value using the income approach based on the present value of expected future cash flows or other appropriate measures of estimated fair value. The Company’s cash flow assumptions consider historical and forecasted revenue and operating costs and other relevant factors. The Company did not record any impairment charges on long‑lived assets during the years ended December 31, 2015, 2016 and 2017. Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, product shipment has occurred, or there are no further obligations yet to be performed, pricing is fixed or determinable, and collection is reasonably assured. The Company makes reasonable assumptions regarding the future collectability of amounts receivable from customers to determine whether the revenue recognition criteria have been met. Taxes assessed by a governmental authority that are directly imposed on revenue‑producing transactions between a seller and a customer are not recorded as revenue. In general, the Company’s standard terms and conditions of sale do not allow for product returns. Sales returns have been limited to damaged product and have not been material. The Company expenses shipping and handling costs as incurred and includes them in the cost of goods sold. In those cases where shipping and handling costs are billed to customers, the Company classifies the amounts billed as a component of cost of goods sold. Cost of Goods Sold Cost of goods sold consists primarily of manufacturing overhead costs, material costs, and direct labor. Overhead costs include the cost of material procurement, inventory control, facilities, equipment, and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs. Research and Development Research and development expenses consist primarily of product development, clinical and regulatory affairs, consulting services, and other costs associated with products and technologies in development. These expenses include employee compensation, stock-based compensation, supplies, travel, and facility costs. Clinical expenses include clinical trial design, clinical site reimbursement, data management, travel expenses, and the cost of manufacturing products for clinical trials. Common Stock Valuation and Stock‑Based Compensation The Company maintains an equity incentive plan to provide long-term incentives for employees, consultants, and members of the board of directors. The plan allows for the issuance of non-statutory and incentive stock options to employees and non-statutory stock options to consultants and non-employee directors. The Company recognizes equity‑based compensation expense for awards of equity instruments to employees and non‑employees based on the grant date fair value of those awards in accordance with FASB ASC Topic 718, Stock Compensation (ASC 718). ASC 718 requires all equity‑based compensation awards to employees and nonemployee directors, including grants of restricted shares and stock options, to be recognized as expense in the statements of operations and comprehensive loss based on their grant date fair values. The Company estimates the fair value of stock options using the Black‑Scholes option pricing model. The Company uses the value of its common stock to determine the fair value of restricted shares. The Company accounts for restricted stock and common stock options issued to nonemployees under FASB ASC Topic 505‑50, Equity‑Based Payments to Non‑Employees (ASC 505‑50). As such, the value of such options is periodically remeasured and income or expense is recognized over their vesting terms. Compensation cost related to awards with service‑based vesting schedules is recognized using the straight‑line method. The Company determines the fair value of the restricted stock and common stock granted to nonemployees as either the fair value of the consideration received or the fair value of the equity instruments issued. The Company has not granted any share‑based awards to its consultants. The Black‑Scholes option pricing model requires the input of certain subjective assumptions, including (i) the expected share price volatility, (ii) the expected term of the award, (iii) the risk‑free interest rate and (iv) the expected dividend yield. Due to the lack of a public market for the trading of the Company’s common stock and a lack of company‑specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The group of representative companies have characteristics similar to the Company, including stage of product development and focus on the life science industry. The Company uses the simplified method, which is the average of the final vesting tranche date and the contractual term, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. For options granted to non‑employees, the Company utilizes the contractual term of the arrangement as the basis for the expected term assumption. The risk‑free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The Company uses an assumed dividend yield of zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock. The Company expenses the fair value of its equity‑based compensation awards granted to employees on a straight‑line basis over the associated service period, which is generally the period in which the related services are received. The Company measures equity‑based compensation awards granted to nonemployees at fair value as the awards vest and recognizes the resulting value as compensation expense at each financial reporting period. The Company accounts for award forfeitures as they occur. Advertising Expenses The Company expenses the costs of advertising, including promotional expenses, as incurred. Advertising expenses were $2.2 million, $3.4 million and $5.5 million during the years ended December 31, 2015, 2016, and 2017, respectively. Income Taxes The Company accounts for income taxes using the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates that will be in effect when the differences are expected to reverse. Valuation allowances against deferred tax assets are established, when necessary, to reduce deferred tax assets to the amounts expected to be realized. As the Company has historically incurred operating losses, the Company has recorded a full valuation allowance against its net deferred tax assets, and there is no provision for income taxes. The Company's policy is to record interest and penalties expense related to uncertain tax positions as other expense in the statements of operations and comprehensive loss. Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on short‑term investments classified as available‑for‑sale, if any. Accumulated other comprehensive loss is presented in the accompanying balance sheets as a component of stockholders’ (deficit) equity. Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because the Company has reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, stock options and warrants were antidilutive in those periods. Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (ASU) No. 2014‑09, Revenue From Contracts With Customers (ASU 2014‑09), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014‑09 will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. In doing so, companies will need to use more judgment and make more estimates than under current guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price, and allocating the transaction price to each separate performance obligation. Under the original pronouncement, ASU 2014‑09 would have been effective for the Company’s annual reporting periods beginning January 1, 2018. In August 2015, the FASB issued ASU No. 2015‑14, which formally defers the effective date of the new revenue standard by one year. As a result, the updated revenue guidance will be effective for the Company’s annual reporting periods beginning January 1, 2019, and early adoption is permitted as of the original effective date contained within the original standard. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that ASU 2014‑09 will have on its financial statements and related disclosures. In July 2015, the FASB issued ASU 2015‑11 Simplifying the Measurement of Inventory , which is intended to narrow down the alternative methods available for valuing inventory. The new guidance does not apply to inventory currently measured using the last‑in‑first‑out or the retail inventory valuation methods. Under the new guidance, inventory valued using other methods, including the first‑in‑first‑out method, must be valued at the lower of cost or net realizable value. This guidance is effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2016. This guidance was effective January 1, 2017 and did not have a material impact on the Company’s financial position, results of operations and cash flows. In November 2015, the FASB issued ASU No. 2015‑17, Balance Sheet Classification of Deferred Taxes (ASU 2015‑17). ASU 2015‑17 is intended to reduce complexity surrounding the presentation of deferred taxes within the balance sheet. Specifically, ASU 2015‑17 requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non‑current on the balance sheet, effectively eliminating the requirement to allocate deferred taxes between current and non‑current amounts. The new guidance does not permit companies to offset deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. ASU 2015‑17 will be effective for the Company’s annual reporting periods beginning January 1, 2018, and can be applied on either a prospective or retrospective basis; early adoption is also permitted. The Company does not expect the ASU 2015‑17 to significantly impact its financial statements and related disclosures. In February 2016, the FASB issued ASU No. 2016‑02, Leases (ASU 2016‑02). ASU 2016‑02 will require entities that lease assets to recognize the rights and obligations associated with those leases on their balance sheets. The guidance will be effective for the Company’s annual reporting period beginning January 1, 2020, with early adoption permitted. The Company is evaluating the impact this standard will have on its financial statements and related disclosures. In March 2016, the FASB issued No. 2016‑09, Improvements to Employee Share‑Based Payment Accounting (ASU 2016‑09), which changes how companies will account for certain aspects of share‑based payments to employees. As part of the new guidance, entities will be required to record the impact of income taxes arising from share‑based compensation when awards vest or are settled within earnings as part of income tax expense rather than recorded as part of additional paid‑in capital (APIC) and will eliminate the requirement that excess tax benefits be realized prior to recognition. Additionally, the guidance requires entities to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. Additionally, companies will be required to make an accounting policy election at the time of adoption of the new guidance to either account for forfeitures of share‑based awards in a manner similar to today’s requirements (i.e., estimating the number of awards expected to be forfeited at the grant date and adjusting the estimate when awards are actually forfeited), or recognizing forfeitures as they occur with no estimate of forfeitures determined at the grant date. Companies will also be able to set a maximum statutory tax rate as it pertains to share‑based awards it net settles on behalf of its employees. This will provide companies a greater ability to retain equity‑award accounting treatment. Entities will apply the provisions of ASU 2016‑09 using a modified retrospective transition approach, with a cumulative‑effect adjustment booked to retained earnings as of the beginning of the period of adoption. The guidance will be effective for the Company’s annual reporting periods beginning January 1, 2018, with early adoption permitted. The Company is evaluating the impact this standard will have on its financial statements and related disclosures. The Company has reviewed and considered all other recent accounting pronouncements and believes there are none that could potentially have a material impact on its business practices, financial condition, results of operations, or disclosures. |
Composition of Certain Financ_6
Composition of Certain Financial Statement Items | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Composition of Certain Financial Statement Items | ||
Composition of Certain Financial Statement Items | Composition of Certain Financial Statement Items Inventories September 30, 2018 December 31, 2017 Raw materials $ 1,054 $ 1,323 Finished goods 2,021 2,347 Total inventories, net of reserves $ 3,075 $ 3,670 Property and Equipment September 30, 2018 December 31, 2017 Computer equipment and software $ 333 $ 351 Furniture and office equipment 148 137 Manufacturing equipment 857 1,108 Research and development equipment 30 30 Leasehold improvements 185 178 Property and equipment, cost 1,553 1,804 Less: accumulated depreciation and amortization (788 ) (810 ) Property and equipment, net $ 765 $ 994 Depreciation and amortization expense was $0.1 million for both the three months ended September 30, 2018 and 2017 , respectively, and $0.3 million and $0.2 million for the nine months ended September 30, 2018 and 2017 , respectively. Accrued Expenses September 30, 2018 December 31, 2017 Payroll and commissions payable $ 3,619 $ 2,871 Vacation 946 723 Other accrued expenses 397 438 Total accrued expenses $ 4,962 $ 4,032 | 3. Composition of Certain Financial Statement Items Inventories Inventory balances, net of reserves, consist of the following: December 31, 2016 2017 Raw materials $ 738 $ 1,323 Finished goods 2,617 2,347 $ 3,355 $ 3,670 Property and Equipment December 31, 2016 2017 Computer equipment and software $ 75 $ 351 Furniture and office equipment 84 137 Manufacturing equipment 1,329 1,108 Research and development equipment 34 30 Leasehold improvements 26 178 1,548 1,804 Less: accumulated depreciation and amortization (681) (810) $ 867 $ 994 Depreciation and amortization expense was $120, $103 and $285 during the years ended December 31, 2015, 2016 and 2017, respectively. Accrued Expenses December 31, 2016 2017 Payroll and commissions payable $ 1,861 $ 2,871 Vacation 564 723 Other accrued expenses 279 438 $ 2,704 $ 4,032 |
Short-Term Investments
Short-Term Investments | 9 Months Ended |
Sep. 30, 2018 | |
Investments, Debt and Equity Securities [Abstract] | |
Short-Term Investments | Short-Term Investments Our short-term investments are classified as available-for-sale and consist of the following: September 30, 2018 Unrealized Cost Gains Losses Fair Value Commercial paper $ 47,631 $ — $ — $ 47,631 Corporate bonds 34,598 — 22 34,576 U.S. government securities 11,911 — 4 11,907 Short-term investments $ 94,140 $ — $ 26 $ 94,114 December 31, 2017 Unrealized Cost Gains Losses Fair Value Commercial paper $ 5,384 $ — $ — $ 5,384 Corporate bonds 1,804 — — 1,804 Short-term investments $ 7,188 $ — $ — $ 7,188 As of September 30, 2018 and December 31, 2017 , we had no investments with a contractual maturity of greater than one year. Currently, we do not intend to sell the 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 maturity. We do not consider those investments to be other-than-temporarily impaired at September 30, 2018 . |
Long-Term Debt_2
Long-Term Debt | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Long-term Debt, by Current and Noncurrent [Abstract] | ||
Long-Term Debt | Long-Term Debt Credit Facility In August 2015, we entered into a loan and security agreement, which provided for a term A loan facility in the amount of $15.5 million , the proceeds of which were used to refinance the $12.0 million of borrowings outstanding under our original credit facility, and a term B loan facility in an amount between $3.5 million and $10.0 million , subject to our achievement of certain revenue milestones. Amounts outstanding under the credit facility bore interest at a fixed rate of 7.95% per annum. In February 2017, we amended the loan and security agreement. Under the loan and security agreement, as amended, and subject to the limitation noted below, amounts outstanding under the credit facility bear interest at a floating interest rate equal to the greater of 7.95% or LIBOR plus 6.9% per annum. Upon execution of the amendment, we borrowed an additional $1.0 million under the term A loan portion of the credit facility, receiving net proceeds of $0.5 million , net of expenses, for a total of $16.5 million outstanding under the credit facility and reduced borrowings available under the term B loan facility to $9.0 million . In connection with the execution of the amendment to the loan and security agreement, we issued 29,197 ten -year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. On February 7, 2018, we borrowed an additional $8.0 million under the term B loan facility portion of the credit facility. After receipt of the $8.0 million , we had a total of $24.5 million outstanding under the credit facility, which bears interest at a floating interest rate equal to the greater of 7.95% or LIBOR plus 6.9% per annum. All amounts borrowed under the credit facility are interest-only through March 1, 2019, after which monthly payments of principal and interest are due through March 1, 2022; provided that the interest-only period will be extended to March 1, 2020 if we have revenue, measured on a trailing 12 -month basis as of December 31, 2018, of at least $25.0 million , which was met during the nine months ended September 30, 2018, and, therefore, the interest-only period is extended to March 1, 2020. In connection with this borrowing, we issued 233,577 ten -year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. In addition to the principal and interest payments, under the credit facility, we are required to pay a final payment fee of 5.0% on all amounts outstanding (or 5.5% if the interest-only period has been extended to March 1, 2020), which is being accreted using the effective interest rate method over the term of the loan and security agreement and shall be due at the earlier of maturity or prepayment. Because the interest-only period has been extended, the final payment fee will be 5.5%. If we repay all the amounts borrowed under the term A loan facility on or prior to maturity, we will also be required to pay a prepayment fee equal to 1.5% if such borrowings are prepaid after February 24, 2018 but prior to February 24, 2019, and 1.00% if such borrowings are prepaid on or after February 24, 2019. Borrowings under the term B loan facility are prepayable at our option in whole, but not in part, together with all accrued and unpaid interest thereon and, if not previously made, the Final Payment, subject to a prepayment fee of 2.5% if the such borrowings are prepaid prior to February 7, 2019, 1.5% if such borrowings are prepaid on or after February 7, 2019 but prior to February 7, 2020 and 1.00% if such borrowings are on or after February 7, 2020. The credit facility includes affirmative and restrictive covenants and events of default, including the following events of default: payment defaults, breaches of covenants, judgment defaults, cross defaults to certain other contracts, certain events with respect to governmental approvals if such events could cause a material adverse change, a material impairment in the perfection or priority of the lender's security interest or in the value of the collateral, a material adverse change in the business, operations, or condition of us or any of our subsidiaries, and a material impairment of the prospect of repayment of the loans. Upon the occurrence of an event of default, a default increase in the interest rate of an additional 5.00% could be applied to the outstanding loan balance and the lender could declare all outstanding obligations immediately due and payable and take such other actions as set forth in the loan and security agreement. Our obligations under the credit facility are secured by a first priority security interest in substantially all of our assets, other than our intellectual property. There are no financial covenants contained in the loan and security agreement. We were in compliance with the affirmative and restrictive covenants as of September 30, 2018 . We paid debt issuance costs of $0.1 million in connection with our entry into the loan and security agreement in August 2015. The costs are being amortized over the term of the loan using the effective interest rate method. We also issued preferred stock warrants in connection with our borrowings under our credit facilities (see Note 8 ). Expected future principal payments for the credit facility are as follows: Year ending December 31 : 2018 (remaining) $ — 2019 — 2020 10,208 2021 12,250 2022 2,042 Total expected future principal payments $ 24,500 | 4. Long‑Term Debt Credit Facility In August 2015, the Company entered into a loan and security agreement, which provided for a term A loan facility in the amount of $15.5 million, the proceeds of which were used to refinance the $12.0 million of borrowings outstanding under the Company's original credit facility, and a term B loan facility in an amount between $3.5 million and $10.0 million, subject to the Company's achievement of certain revenue milestones. Amounts outstanding under the credit facility bore interest at a fixed rate of 7.95% per annum. The Company had $15.5 million outstanding under the credit facility as of December 31, 2015. In February 2017, the Company amended the loan and security agreement. Under the loan and security agreement, as amended, and subject to the limitation noted below, amounts outstanding under the credit facility bear interest at a floating interest rate equal to the greater of 7.95% or LIBOR plus 6.9% per annum. Upon execution of the amendment, the Company borrowed an additional $1.0 million under the term A loan portion of the credit facility, receiving net proceeds of $0.5 million, net of expenses, for a total of $16.5 million outstanding under the credit facility and reduced borrowings available under the term B loan facility to $9.0 million.All amounts borrowed under the credit facility are interest-only through March 1, 2019, after which the Company will make monthly payments of principal and interest through February 2022; provided that the interest-only period will be extended to March 1, 2020 if the Company has revenue, measured on a trailing 12-month basis as of December 31, 2018, of at least $25.0 million. In connection with the execution of the amendment to the loan and security agreement, the Company issued 29,197 ten-year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. In addition to the principal and interest payments, under the credit facility, the Company is required to pay a final payment fee of 5.0% on all amounts outstanding, which is being accreted using the effective interest rate method over the term of the loan and security agreement and shall be due at the earlier of maturity or prepayment. If the Company repays all the amounts borrowed under the term A loan facility on or prior to maturity, the Company will also be required to pay a prepayment fee equal to 2.5% if such borrowings are prepaid prior to February 24, 2018, 1.5% if such borrowings are prepaid on or after February 24, 2018 but prior to February 24, 2019, and 1.00% if such borrowings are prepaid on or after February 24, 2019. Borrowings under the term B loan facility are prepayable at the Company's option in whole, but not in part, together with all accrued and unpaid interest thereon and, if not previously made, the Final Payment, subject to a prepayment fee of 2.5% if the such borrowings are prepaid prior to February 7, 2019, 1.5% if such borrowings are prepaid on or after February 7, 2019 but prior to February 7, 2020 and 1.00% if such borrowings are on or after February 7, 2020. The credit facility includes affirmative and restrictive covenants and events of default, including the following events of default: payment defaults, breaches of covenants, judgment defaults, cross defaults to certain other contracts, certain events with respect to governmental approvals if such events could cause a material adverse change, a material impairment in the perfection or priority of the lender’s security interest or in the value of the collateral, a material adverse change in the business, operations, or condition of the Company or any of its subsidiaries, and a material impairment of the prospect of repayment of the loans. Upon the occurrence of an event of default, a default increase in the interest rate of an additional 5.00% could be applied to the outstanding loan balance and the lender could declare all outstanding obligations immediately due and payable and take such other actions as set forth in the loan and security agreement. The Company's obligations under the credit facility are secured by a first priority security interest in substantially all of its assets, other than its intellectual property. There are no financial covenants contained in the loan and security agreement. The Company was in compliance with the affirmative and restrictive covenants as of December 31, 2016 and 2017. The Company paid debt issuance costs of $72 in connection with its entry into the loan and security agreement in August 2015. The costs are being amortized over the term of the loan using the effective interest rate method. The Company also issued preferred stock warrants in connection with its borrowings under its credit facilities (see Note 7). Expected future principal payments for the credit facility are as follows: Year ending December 31: 2018 $ — 2019 4,583 2020 5,500 2021 5,500 2022 917 $ 16,500 |
Commitments_2
Commitments | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Commitments and Contingencies Disclosure [Abstract] | ||
Commitments | Commitments Operating Lease We rent office space under an operating lease that expires on March 31, 2019. The lease allows us to terminate the lease any time after March 31, 2017 without a penalty. In September 2018, we entered into a non-cancelable operating lease agreement to sublease approximately 44,000 square feet of office space for our corporate headquarters, which lease is scheduled to commence January 15, 2019 and expire November 30, 2020. Future minimum annual operating lease payments are as follows: Year ending December 31 : 2018 (remaining) $ 48 2019 1,043 2020 952 Total future operating lease payments $ 2,043 Rent expense was less than $0.1 million for both the three months ended September 30, 2018 and 2017 , and $0.1 million for both the nine months ended September 30, 2018 and 2017 . Purchase Commitments As of September 30, 2018 and December 31, 2017 , we had commitments to suppliers for inventory purchases totaling $16.2 million and $9.0 million , respectively, of which less than $0.1 million and $0.4 million , respectively, was committed to Medtronic, a related party. | 5. Commitments Operating Lease The Company rents office space under an operating lease that expires on March 31, 2019. The lease allows the Company to terminate the lease any time after March 31, 2017 without a penalty. Future minimum annual operating lease payments are as follows: Years ending December 31: 2018 $ 190 2019 48 Total $ 238 Rent expense was $123, $127 and $184 during the years ended December 31, 2015, 2016 and 2017, respectively. Purchase Commitments As of December 31, 2016, and 2017, the Company had commitments to suppliers for inventory purchases totaling $6.1 million and $9.0 million, respectively, of which $0.6 million and $0.4 million, respectively, was committed to Medtronic, a related party. |
Employee Retirement Plan_2
Employee Retirement Plan | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Retirement Benefits [Abstract] | ||
Employee Retirement Plan | Employee Retirement Plan We sponsor an employee retirement plan covering all of our full-time employees. The plan allows for eligible employees to defer a portion of their eligible compensation up to the maximum allowed by IRS Regulations. We may elect to make a voluntary contribution to the plan. We have not made contributions since inception. | 6. Employee Retirement Plan The Company sponsors an employee retirement plan covering all full- time employees of the Company. The plan allows for eligible employees to defer a portion of their eligible compensation up to the maximum allowed by IRS Regulations. The Company may elect to make a voluntary contribution to the plan. The Company did not make contributions for the years ended December 31, 2015, 2016 and 2017. |
Stockholders' Equity_2
Stockholders' Equity | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Stockholders' Equity Note [Abstract] | ||
Stockholders' Equity | Stockholders' Equity Authorized Shares As of December 31, 2017, we had authorized 186,894,620 shares of stock, of which 110,000,000 shares were designated as common stock and 76,894,620 shares were designated as Series A, B, C, D, E, and F preferred stock. All stock had a par value of $0.001 per share. As of September 30, 2018 , we had authorized 210,000,000 shares of stock, of which 200,000,000 shares are designated as common stock and 10,000,000 shares are designated as preferred stock. All stock has a par value of $0.001 per share. Preferred Stock A summary of preferred stock and its terms as of December 31, 2017, is as follows: Series Shares Authorized Shares Issued and Outstanding Carrying Value Liquidation Preference per Share 8% Dividend per Share Conversion Price per Share A 5,375,507 5,375,507 $ 5,037 $ 1.00 $ 0.08 $ 6.65 B 8,706,909 8,706,909 15,913 1.84 0.15 9.91 C 14,091,589 13,829,906 14,949 1.07 0.09 7.12 D 5,683,292 5,683,292 6,043 1.07 0.09 7.12 E 15,373,091 15,267,175 39,848 2.62 0.21 15.16 F 27,664,232 27,372,261 37,316 1.37 0.11 9.11 Total 76,894,620 76,235,050 $ 119,106 In connection with the IPO in May 2018, the 76,235,050 shares of convertible preferred stock were converted into 12,111,706 shares of common stock, resulting in the reclassification of the related convertible preferred stock of $119.1 million to common stock and APIC. As of September 30, 2018 , no preferred stock had been issued. The dividend per share on the convertible preferred stock was only payable when and if declared by the Board of Directors. Preferred Stock Warrants and Common Stock Warrants As of December 31, 2017, we had warrants outstanding to purchase 396,795 shares of various series of our preferred stock. The warrants had been issued in connection with our various credit facilities and issuances of promissory notes. The original fair value of the warrants was determined using the Black-Scholes option pricing model. In connection with the borrowing completed in February 2018 (see Note 5 ), we issued 233,577 ten -year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. Based on the Black-Scholes option pricing model, the value of each warrant was determined to be $0.44 , for a total value of $0.1 million at the date of issuance and was fully expensed during the three months ended March 31, 2018. The preferred stock warrants issued in connection with the execution of the original credit facility and its subsequent amendments required re-measurement of the value of the preferred stock warrants each period, with changes in fair value recognized within other expenses on the statements of operations and comprehensive loss. The fair value of the preferred stock warrants was determined using the Black-Scholes option pricing model. As of May 7, 2018, the date of the closing of our IPO, the following preferred stock warrants issued under the original credit facility and subsequent amendments were outstanding and exercisable: Issuance Expiration Series Exercise Price Warrants Outstanding at May 7, 2018 Initial Value Fair Value at May 7, 2018 February 8, 2018 February 8, 2028 F $ 1.37 233,577 $ 103 $ 320 February 24, 2017 February 24, 2027 F 1.37 29,197 4 40 August 7, 2015 August 7, 2025 E 2.62 29,580 33 41 June 27, 2014 June 27, 2024 E 2.62 76,334 85 174 August 5, 2013 August 5, 2023 C 1.07 74,768 39 80 November 16, 2012 November 16, 2022 C 1.07 186,916 96 200 Total 630,372 $ 855 In connection with the closing of the IPO in May 2018, the warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock, resulting in the reclassification of the related convertible preferred stock warrant liability of $0.9 million to APIC during the three months ended June 30, 2018. Upon the closing of the IPO, the warrants to purchase 630,372 shares of preferred stock at a weighted average exercise price of $1.46 per share became exercisable to purchase 100,558 shares of common stock at weighted average exercise price of $9.38 per share. Warrants for 19,674 shares were exercised through a cashless exercise on September 10, 2018 , resulting in the issuance of a net 17,050 shares of our common stock. As of December 31, 2017, the following preferred stock warrants issued under the original credit facility and subsequent amendments were outstanding and exercisable: Issuance Expiration Series Exercise Price Warrants Outstanding at December 31, 2017 Initial Value Fair Value at December 31, 2017 February 24, 2017 February 24, 2027 F $ 1.37 29,197 $ 4 $ 13 August 7, 2015 August 7, 2025 E 2.62 29,580 33 8 June 27, 2014 June 27, 2024 E 2.62 76,334 85 21 August 5, 2013 August 5, 2023 C 1.07 74,768 39 33 November 16, 2012 November 16, 2022 C 1.07 186,916 96 82 Total 396,795 $ 157 The warrants issued on August 7, 2015 to purchase Series E preferred stock were subject to the conversion price of the underlying preferred stock. The warrants to purchase 29,580 shares of Series E preferred stock at $2.62 per share has been adjusted to purchase 56,569 shares of Series F preferred stock at $1.37 per share due to the dilutive issuance of the Series F preferred stock. | 7. Stockholders’ (Deficit) Equity Authorized Shares The Company has authorized 186,894,620 shares of stock, of which 110,000,000 shares are designated as common stock and 76,894,620 shares are designated as Series A, B, C, D, E, and F preferred stock. All stock has a par value of $0.001. Preferred Stock A summary of the Company’s preferred stock as of December 31, 2016 and 2017, is as follows: 2016 Shares Shares Issued and Carrying Series Authorized Outstanding Value A 5,375,507 5,375,507 $ 5,037 B 8,706,909 8,706,909 15,913 C 14,091,589 13,829,906 14,949 D 5,683,292 5,683,292 6,043 E 15,373,091 15,267,175 39,848 F 9,124,084 9,124,084 12,348 58,354,472 57,986,873 $ 94,138 2017 Shares Shares Issued and Carrying Series Authorized Outstanding Value A 5,375,507 5,375,507 $ 5,037 B 8,706,909 8,706,909 15,913 C 14,091,589 13,829,906 14,949 D 5,683,292 5,683,292 6,043 E 15,373,091 15,267,175 39,848 F 27,664,232 27,372,261 37,316 76,894,620 76,235,050 $ 119,106 A summary of the Company’s convertible preferred stock terms is as follows: Liquidation 8% Conversion Preference Dividend Price per Series per Share per Share Share A $ $ $ B C D E F The dividend per share on the convertible preferred stock is only payable when, as and if declared by the Board of Directors. The Company has issued 5,375,507 shares of Preferred Stock, Series A, with an original issue price of $1.00 per share. Each share of Series A Preferred Stock may be converted into 0.1504 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series A Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series A Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. The Company has issued 8,706,909 shares of Preferred Stock, Series B, with an original issue price of $1.84 per share. Each share of Series B Preferred Stock may be converted into 0.1855 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Ownership of Series B Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock. Each share of Series B Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. The Company has issued 13,829,906 shares of Preferred Stock, Series C, with an original issue price of $1.07 per share. Each share of Series C Preferred Stock may be converted into 0.1504 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series C Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series C Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. The Company has issued 5,683,292 shares of Preferred Stock, Series D, with an original issue price of $1.07 per share. Each share of Series D Preferred Stock may be converted into 0.1504 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series D Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series D Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. In March 2014, the Company raised $39.8 million, net of stock issuance costs, through the issuance of 15,267,175 shares of Series E Preferred Stock, with an original issue price of $2.62 per share. Each share of Series E Preferred Stock may be converted into 0.1728 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series E Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series E Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. In October 2016, the Company raised $12.3 million, net of stock issuance costs, through the issuance of 9,124,084 shares of Series F Preferred Stock, with an original issue price of $1.37 per share (Tranche 1). In February 2017, the Company raised $25.0 million, net of stock issuance costs, through the issuance of 18,248,177 shares of Series F Preferred Stock, with an original issue price of $1.37 per share (Tranche 2). Each share of Series F Preferred Stock may be converted into 0.1504 shares of common stock. The conversion price is subject to change for certain subdivisions, combinations of common stock, or other dilutive issuances of common stock. Each share of Series F Preferred Stock entitles the holder to vote on all matters submitted to holders of common stock, and each share of Series F Preferred Stock has the number of votes equal to the number of shares of common stock into which it may be converted. Upon a liquidation, dissolution, or winding up of the Company, the holders of the Series F Preferred Stock shall be entitled to receive prior and in preference to any distribution of any of the assets of the Company to holders of Series A Preferred, Series B Preferred, Series C Preferred, Series D Preferred, Series E Preferred and common stock. If, upon a liquidation, the assets to be distributed to the holders of the Series F Preferred are insufficient to permit the payment to such holders of the full amount payable, then the entire assets of the Company legally available for distribution shall be distributed pro rata to the holders of the Series F Preferred Stock in proportion to the full preferential amounts which each such holder would otherwise be entitled to receive. Preferred Stock Warrants In connection with certain convertible promissory notes issued by the Company during 2011 and 2012 and subsequently paid, the Company issued 278,506 five‑year warrants to purchase Series C preferred shares of stock at an exercise price of $1.07 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $0.34, for a total value of $94, and was fully expensed during the year ended December 31, 2012. As of December 31, 2015, the Company had a total of 258,880 outstanding warrants. In 2016, a total of 258,880 Series C preferred shares were issued upon exercise of the entire remaining warrants for proceeds of $277. In connection with the execution of the Company’s original credit facility entered into during 2012, the Company issued 186,916 ten‑year warrants to purchase Series C preferred shares of stock at an exercise price of $1.07 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $0.515, for a total value of $96 at the date of issuance and was fully expensed during the year ended December 31, 2012. In connection with the added borrowings drawn upon the Company’s original credit facility in 2013, the Company issued 74,768 ten‑year warrants to purchase Series C preferred shares of stock at an exercise price of $1.07 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $0.525, for a total value of $39 at the date of issuance and was fully expensed during the year ended December 31, 2013. In connection with the execution of the Company’s amended credit facility completed in June 2014, the Company also issued 76,334 ten‑year warrants to purchase Series E preferred shares of stock at an exercise price of $2.62 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $1.11, for a total value of $85 at the date of issuance and was fully expensed during the year ended December 31, 2014. In connection with the execution of the Company’s current credit facility completed in August 2015 (see Note 4), the Company issued 29,580 ten‑year warrants to purchase Series E preferred shares of stock at an exercise price of $2.62 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $1.13, for a total value of $33 at the date of issuance and was fully expensed during the year ended December 31, 2015. In connection with the execution of the amendment to the Company’s current credit facility completed in February 2017 (see Note 4), the Company issued 29,197 ten‑year warrants to purchase Series F preferred shares of stock at an exercise price of $1.37 per share. Based on the Black‑Scholes option pricing model, the value of each warrant was determined to be $0.13, for a total value of $4 at the date of issuance and was fully expensed during the year ended December 31, 2017. The preferred stock warrants issued in connection with the execution of the original credit facility and its subsequent amendments require re-measurement of the value of the preferred stock warrants each period, with changes in fair value recognized within other expenses on the statements of operations and comprehensive loss. The fair value of the preferred stock warrants was determined using the Black-Scholes option pricing model. As of December 31, 2016 and 2017, the following preferred stock warrants issued under the Company’s original credit facility and subsequent amendments were outstanding and exercisable: Warrants Fair Outstanding at Value at Dates Exercise December 31, Initial December 31, Issuance Expiration Series Price 2016 Value 2016 August 7, 2015 August 7, 2025 E $ 2.62 29,580 $ 33 $ 4 June 27, 2014 June 27, 2024 E 2.62 76,334 85 10 August 5, 2013 August 5, 2023 C 1.07 74,768 39 11 November 16, 2012 November 16, 2022 C 1.07 186,916 96 28 367,598 $ 53 Warrants Fair Outstanding at Value at Dates Exercise December 31, Initial December 31, Issuance Expiration Series Price 2017 Value 2017 February 24, 2017 February 24, 2027 F $ 1.37 29,197 $ 4 $ 13 August 7, 2015 August 7, 2025 E 2.62 29,580 33 8 June 27, 2014 June 27, 2024 E 2.62 76,334 85 21 August 5, 2013 August 5, 2023 C 1.07 74,768 39 33 November 16, 2012 November 16, 2022 C 1.07 186,916 96 82 396,795 $ 157 The warrants issued on August 7, 2015 to purchase Series E preferred stock are subject to the conversion price of the underlying preferred stock. The warrants to purchase 29,580 shares of Series E preferred stock at $2.62 per share has been adjusted to purchase 56,569 shares of Series F preferred stock at $1.37 per share due to the dilutive issuance of the Series F preferred stock. |
Stock Options_2
Stock Options | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | ||
Stock Options | Stock Options We adopted the 2007 Stock Incentive Plan (the "2007 Plan") in November 2007, which terminated in accordance with its terms on November 28, 2017; however, the outstanding stock options may continue to be exercised in accordance with their terms. Immediately following the termination of the 2007 Plan, we adopted the 2017 Stock Incentive Plan (the "2017 Plan"), which contains substantially similar terms and conditions as the 2007 Plan. Upon the IPO, no further grants were made under the 2017 Plan and we adopted the 2018 Stock Incentive Plan (the "2018 Plan"). The purpose of the 2018 Plan is to promote the interest of our company and our stockholders by aiding in attracting and retaining employees, officers, consultants, independent contractors, and directors capable of assuring the future success our business and to afford such persons an opportunity to acquire a proprietary interest our company. The Board may amend, alter, suspend, discontinue, or terminate the 2018 Plan at any time with the approval of our stockholders. As of September 30, 2018 , there were 1,386,809 shares reserved for issuance under the 2018 Plan, of which 1,036,392 shares were available for issuance. Prior to the IPO, the exercise price of stock options represented fair value of the common stock at the time of issuance and was determined by the Board of Directors. Post-IPO, options are granted at the exercise price, which is equal to the closing price of our stock on the date of grant. The options granted during the nine months ended September 30, 2018 contain fixed exercise prices ranging from $2.80 to $54.99 per share with varying expiration and exercise dates and have a weighted average exercise price of $15.04 per share. The stock options granted to employees include a four-year service period and 25% vest after the first year of service and with the remainder vesting pro rata over the next 36 months of service. The stock options granted to the Board of Directors include a one-year service period and all shares vest after the one year of service. The stock options have a contractual life of ten years . A summary of stock option activity and related information is as follows: Options Weighted Average Exercise Price Weighted average remaining contractual term (years) Aggregate intrinsic value (in thousands) Outstanding at December 31, 2017 2,071,616 $ 1.47 5.9 Granted 385,056 $ 15.04 Exercised (227,114 ) $ 1.90 Forfeited (31,428 ) $ 1.05 Outstanding at September 30, 2018 2,198,130 $ 3.80 6.8 $ 84,136 Exercisable at September 30, 2018 1,307,821 $ 1.58 5.4 $ 52,975 Total stock-based compensation recognized, before taxes, during the three and nine months ended September 30, 2018 and 2017 , is as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 General and administrative $ 326 $ 41 $ 592 $ 89 Sales and marketing 41 30 88 73 Research and development 5 10 16 27 Total stock-based compensation $ 372 $ 81 $ 696 $ 189 As of September 30, 2018 , the amount of unearned stock-based compensation currently estimated to be expensed from now through the year 2022 related to unvested employee and non-employee director share-based awards is $2.4 million and the weighted average period over which the unearned stock-based compensation is expected to be recognized is 2.6 years. If there are any modifications or cancellations of the underlying unvested securities, we may be required to accelerate, increase, or cancel any remaining unearned stock compensation expense. Future stock-based compensation expense and unearned stock-based compensation will increase to the extent that we grant additional share-based awards. We estimate the fair value of share-based awards on the date of grant using the Black-Scholes option pricing model using the fair market value of our common stock on the date of grant and a number of other complex and subjective assumptions. These assumptions include, but are not limited to, estimates regarding the expected term of our outstanding awards, estimates of the stock volatility over a duration that approximates the expected life of our outstanding awards, estimates of the risk-free rate, and estimates of expected dividend rates. Due to our limited amount of historical exercise, forfeiture, and expiration activity, we have opted to use the "simplified method" for estimating the expected term of options, whereby the expected term equals the arithmetic average of the vesting terms and the original contractual term of the option. We will continue to analyze our expected term assumption as more historical data becomes available. Due to our limited operating history and a lack of company specific historical and implied volatility data, we have based our estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. When selecting these public companies on which we have based our expected stock price volatility, we generally selected companies with comparable characteristics to it, including enterprise value, stages of clinical development, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. The historical volatility data was computed using the daily closing prices for the selected companies' shares over historical periods that approximate calculated expected term of our share-based awards. We will continue to analyze the historical stock price volatility assumption as more historical data for our common stock becomes available. The risk-free rate assumption is based on the U.S. Treasury instruments with maturities similar to the expected term of our stock options. The expected dividend assumption is based on our history of not paying dividends and our expectation that we will not declare dividends for the foreseeable future. The amount of stock-based compensation expense recognized is based on awards ultimately expected to vest. The amount of expense recognized has been reduced by actual forfeitures as they occur. The fair value of options granted to employees and non-employee directors during the nine months ended September 30, 2018 and 2017 was estimated as of the grant date using the Black-Scholes option pricing model using the following assumptions: Nine Months Ended September 30, 2018 2017 Expected life (years) 5.50 - 6.25 5.75 - 6.25 Expected volatility 37.5 - 49.8% 39.9 - 41.5% Risk-free interest rate 2.38 - 3.01% 1.88 - 2.32% Dividend yield 0.0% 0.0% Weighted average fair value $7.43 $0.40 | 8. Stock Options The Company adopted the 2007 Stock Incentive Plan (the Plan) in November 2007. The purpose of the Plan is to promote the interest of the Company and its stockholders by aiding the Company in attracting and retaining employees, officers, consultants, independent contractors, and directors capable of assuring the future success of the Company’s business and to afford such persons an opportunity to acquire a proprietary interest in the Company. The Board may amend, alter, suspend, discontinue, or terminate the Plan at any time with the approval of the stockholders of the Company. As of December 31, 2017, the number of shares reserved for issuance under the plan is 2,945,384 shares . The exercise price of stock options represent fair value of the common stock at the time of issuance and is determined by the Board of Directors. The options granted contain fixed exercise prices ranging from $0.94 to $6.65 per share with varying expiration and exercise dates. The stock options granted by the Company to employees during 2015, 2016 and 2017 have a weighted average exercise price of $2.07, $1.65 and $0.94, respectively. The stock options granted include a four year service period and 25% vest after the first year of service and then pro rata over the next 36 months of service. The stock options have a contractual life of ten years. A summary of the Company’s stock option activity and related information is as follows: Weighted Average Options Exercise Price Outstanding at December 31, 2014 1,534,672 $ 1.77 Granted 49,235 2.07 Exercised (21,545) 1.96 Forfeited (21,199) 1.15 Outstanding at December 31, 2015 1,541,163 1.77 Granted 120,277 1.65 Exercised (109,079) 1.74 Forfeited (54,850) 1.87 Outstanding at December 31, 2016 1,497,511 1.76 Granted 721,763 0.94 Exercised (127,122) 1.85 Forfeited (20,536) 1.88 Outstanding at December 31, 2017 2,071,616 1.47 Exercisable at December 31, 2017 1,236,255 1.75 At December 31, 2015, the Company had 1,541,163 common stock options outstanding, with an average remaining contractual life of 6.6 years at a weighted average exercise price of $1.77 per share. At December 31, 2016, the Company had 1,497,511 common stock options outstanding, with an average remaining contractual life of 5.8 years at a weighted average exercise price of $1.76 per share. At December 31, 2017, the Company had 2,071,616 common stock options outstanding, with an average remaining contractual life of 5.9 years at a weighted average exercise price of $1.47 per share. Total stock compensation recognized, before taxes, during the years ended December 31, 2015, 2016 and 2017, is as follows: Year ended December 31 2015 2016 2017 General and administrative $ 147 $ 108 $ 116 Sales and marketing 99 90 84 Research and development 59 50 43 $ 305 $ 248 $ 243 As of December 31, 2017, the amount of unearned stock compensation currently estimated to be expensed from now through the year 2021 related to unvested employee and non-employee director share-based awards is $318 and the weighted average period over which the unearned stock compensation is expected to be recognized is 3 years. If there are any modifications or cancellations of the underlying unvested securities, the Company may be required to accelerate, increase, or cancel any remaining unearned stock compensation expense. Future stock compensation expense and unearned stock compensation will increase to the extent that the Company grants additional share-based awards. The Company estimates the fair value of share-based awards on the date of grant using the Black- Scholes option pricing model using the fair market value of the Company’s common stock on the date of grant and a number of other complex and subjective assumptions. These assumptions include, but are not limited to, estimates regarding the expected term of the Company’s outstanding awards, estimates of the stock volatility over a duration that approximates the expected life of the Company’s outstanding awards, estimates of the risk- free rate, and estimates of expected dividend rates. Due to the Company’s limited amount of historical exercise, forfeiture, and expiration activity, the Company has opted to use the “simplified method” for estimating the expected term of options, whereby the expected term equals the arithmetic average of the vesting terms and the original contractual term of the option. The Company will continue to analyze its expected term assumption as more historical data becomes available. Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. When selecting these public companies on which it has based its expected stock price volatility, the Company generally selected companies with comparable characteristics to it, including enterprise value, stages of clinical development, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock- based awards. The historical volatility data was computed using the daily closing prices for the selected companies’ shares over historical periods that approximate calculated expected term of the Company’s share- based awards. The Company will continue to analyze the historical stock price volatility assumption as more historical data for the Company’s common stock becomes available. The risk- free rate assumption is based on the U.S. Treasury instruments with maturities similar to the expected term of the Company’s stock options. The expected dividend assumption is based on the Company’s history of not paying dividends and its expectation that it will not declare dividends for the foreseeable future. The amount of stock compensation expense recognized is based on awards ultimately expected to vest. Due to the Company’s limited forfeiture activity and its vesting terms, the amount of expense recognized by the Company has been reduced by actual forfeitures as they occur. The Company will continue to analyze its historical forfeitures as more historical data becomes available. The fair value of options granted to employees or non- employee directors during the years ended December 31, 2015, 2016 and 2017 was estimated as of the grant date using the Black-Scholes option pricing model, assuming the weighted average assumptions listed in the following table: Year ended December 31, 2015 2016 2017 Expected life (years) Expected volatility % % % Risk-free interest rate 1.65 - 2.14 % 1.27 - 2.25 % 1.88 - 2.32 % Dividend yield 0.0 % 0.0 % 0.0 % Weighted average fair value $ 0.86 $ 0.47 $ 0.40 |
Related-Party Transactions_2
Related-Party Transactions | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Related Party Transactions [Abstract] | ||
Related-Party Transactions | Related-Party Transactions Board of Directors' Appointment We are party to various agreements and contracts with Medtronic, one of our stockholders. Under these agreements and contracts, Medtronic was allowed to name one person to be a member of our Board of Directors. In connection with the Series F Preferred Stock purchase agreement in 2016, Medtronic agreed to move from one voting member of our Board of Directors to two non-voting members. This right terminated in connection with the completion of our IPO. Supply Agreement We contract with Medtronic to supply all of our commercial and clinical requirements of certain components used to manufacture the Inspire system. The current Supply Agreement expired on June 5, 2017 but was extended to allow Medtronic to complete a final build of the pressure sensor used in our original pressure sensing lead, which was completed in 2018. Upon a change of control event whereby we are owned or controlled by a competitor of Medtronic, Medtronic would have the right to terminate the Supply Agreement, provided that, upon any such termination we would be entitled to exercise a one -time buy right of inventory using current product pricing and upon terms to be agreed upon in the definitive agreements. We purchased inventory at arms-length with Medtronic, a related party, of $0.3 million and $0.8 million for the nine months ended September 30, 2018 and 2017 , respectively. Right-of-First-Offer of the Company Under a Right-of-First-Offer with Medtronic that expired on May 16, 2017, had we decided to initiate a possible sale of our company prior to the expiration date, we would have been required to negotiate exclusively with Medtronic for such transaction for a period of 90 days prior to negotiating with a third party. | 9. Board of Directors’ Appointment The Company has entered into various agreements and contracts with Medtronic, one of the Company’s stockholders. Under these various agreements and contracts, Medtronic is allowed to name one person to be a member of the Company’s Board of Directors. In connection with the Series F Preferred Stock purchase agreement in 2016, Medtronic agreed to move from one voting member of the Company's Board of Directors to two non‑voting members. Supply Agreement The Company contracts with Medtronic to supply all of the Company’s commercial and clinical requirements of certain components used to manufacture the Inspire system. The current Supply Agreement expired on June 5, 2017, but was extended to allow Medtronic to complete a final build of the pressure sensor used in the Company’s original pressure sensing lead, which is expected to be completed in early 2018. Upon a change of control event whereby the Company is owned or controlled by a competitor of Medtronic, Medtronic would have the right to terminate the Supply Agreement, provided that, upon any such termination the Company would be entitled to exercise a one‑ time buy right of inventory using current product pricing and upon terms to be agreed upon in the definitive agreements. Development Agreement As part of the Development Agreement, Medtronic provided support to the Company for product development and was reimbursed on an hourly basis. The Medtronic services included project management, engineering, manufacturing, product quality, and testing of products. The Company continued to be responsible for all marketing, clinical, and regulatory efforts related to product development activities. The Development Agreement expired in 2015. The Company has transactions at arms- length with Medtronic, a related party. These transactions are summarized for the years ended December 31, 2015, 2016 and 2017 as follows: 2015 2016 2017 Inventory purchases $ 834 $ 848 $ 1,120 Research and development expenses 98 — — $ 932 $ 848 $ 1,120 Right‑of‑First‑Offer of the Company Under a Right- of- First- Offer with Medtronic that expired on May 16, 2017, had the Company decided to initiate a possible sale of the Company prior to the expiration date, it would have been required to negotiate exclusively with Medtronic for such transaction for a period of 90 days prior to negotiating with a third party. |
Income Taxes_2
Income Taxes | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Income Tax Disclosure [Abstract] | ||
Income Taxes | Income Taxes During the three and nine months ended September 30, 2018 and 2017 , we did not record an income tax benefit related to our loss before income taxes in the statement of operations and comprehensive loss because a valuation allowance has been required to be established for all deferred tax assets due to our cumulative net loss position. As of December 31, 2017 , our gross federal net operating loss carryforwards of $110.9 million will expire at various dates beginning in 2028. In addition, net operating loss carryforwards for state income tax purposes of $65.9 million that include net operating losses that will begin to expire in 2028. We also have R&D credit carryforwards of $1.4 million as of December 31, 2017 of which will expire at various dates beginning in 2032. Utilization of the net operating loss carryforwards may be subject to an annual limitation due to the ownership change limitations provided by Section 382 of the Internal Revenue Code of 1986 and similar state provisions. The annual limitation may result in the expiration of the net operating loss before utilization. Realization of the deferred tax assets is dependent upon the generation of future taxable income, if any, the amount and timing of which are uncertain. Based on available objective evidence and cumulative losses, management believes it is more likely than not that the deferred tax assets are not recognizable and will not be recognizable until we have sufficient taxable income. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. We had no unrecognized tax benefits as of September 30, 2018 and December 31, 2017 . We file income tax returns in the U.S. federal and various state jurisdictions. The 2014 to 2017 tax years remain open to examination by the major taxing authorities to which we are subject. We do not expect a significant change to our unrecognized tax benefits over the next 12 months . The Tax and Jobs Act (the "Act") was enacted on December 22, 2017. The Act reduces the U.S. federal corporate tax rate from 35% to 21% , requires companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax deferred and creates new taxes on certain foreign-sourced earnings. We have applied the guidance in ASU 2018-5, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 , when accounting for the enactment-date effects of the Act. At September 30, 2018 , we have not completed our accounting for the tax effects of the Act, as we are in the process of analyzing certain aspects of the Act, obtaining information, and refining our calculations of the Act's impact. There have been no material measurement period adjustments made during the nine months ended September 30, 2018 related to the provisional amounts recorded and disclosed in our Registration Statement Form S-1 and Prospectus dated May 2, 2018. We expect to complete the accounting for the tax effects of the Act during 2018. | 10. Income Taxes During the years ended December 31, 2015, 2016 and 2017, the Company did not record an income tax benefit related to its loss before income taxes in the statement of operations and comprehensive loss because a valuation allowance has been required to be established for all deferred tax assets due to its cumulative net loss position. The components of the Company’s provision for income taxes are as follows: Year ended December 31 2015 2016 2017 Tax at federal statutory rate 35.0 % 35.0 % 35.0 % State, net of federal benefit 2.4 2.8 3.0 Permanent items (0.8) (0.5) (1.1) Research and development (R&D) tax credit 1.4 1.3 1.2 Federal tax rate change — — (92.6) Other 4.5 7.1 1.1 Change in valuation allowance (42.5) (45.7) 53.4 Total — — — On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the Act) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system, and a one- time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. We have accounted for our best provisional estimate of the impact of the Act in our 2017 income tax provision, the period in which the legislation was enacted, in accordance with our understanding of the Act and guidance available as of the date of this filing. The provisional amount recorded related to the remeasurement of our deferred tax assets and liabilities, based on the lower tax rates at which they are expected to reverse in the future, was $16.2 million of expense. This tax expense was entirely offset by an income tax benefit related to the reduction of our deferred tax asset valuation allowance of the same amount, resulting in no net impact to tax expense or benefit. The Company also provisionally estimates that it does not have any foreign earnings and therefore is not subject to any one- time transition tax on the mandatory deemed repatriation of foreign earnings. Significant components of net deferred tax assets are as follows: December 31 2015 2016 2017 Deferred tax assets: Net operating losses $ 28,385 $ 36,626 $ 27,827 R&D tax credits 956 1,093 1,368 R&D expenditures, capitalized for tax 2,515 2,682 2,146 Accruals and other 1,165 1,065 753 33,020 41,466 32,094 Deferred tax liabilities: Depreciation and amortization (28) (4) 4 Net deferred tax assets 32,992 41,462 32,098 Valuation allowance (32,992) (41,462) (32,098) $ — $ — $ — Deferred income taxes reflect the tax effects of net operating loss and tax credit carryforwards and the net temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. As of December 31, 2017, the Company’s gross federal net operating loss carryforwards of $110.9 million will expire at various dates beginning in 2028. In addition, net operating loss carryforwards for state income tax purposes of $65.9 million that include net operating losses that will begin to expire in 2028. The Company also has R&D credit carryforwards of $1.4 million as of December 31, 2017 of which will expire at various dates beginning in 2032. Utilization of the net operating loss carryforwards may be subject to an annual limitation due to the ownership change limitations provided by Section 382 of the Internal Revenue Code of 1986 and similar state provisions. The annual limitation may result in the expiration of the net operating loss before utilization. Realization of the deferred tax assets is dependent upon the generation of future taxable income, if any, the amount and timing of which are uncertain. Based on available objective evidence and cumulative losses, management believes it is more likely than not that the deferred tax assets are not recognizable and will not be recognizable until the Company has sufficient taxable income. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $9.1 million and $8.5 million during the years ended December 31, 2015 and 2016, respectively, and decreased by $9.4 million during the year ended December 31, 2017. The Company had no unrecognized tax benefits as of December 31, 2016 and 2017. The Company files income tax returns in the U.S. federal and various state jurisdictions. The 2014 to 2017 tax years remain open to examination by the major taxing authorities to which the Company is subject. The Company does not expect a significant change to its unrecognized tax benefits over the next 12 months. The Company’s policy is to record interest related to uncertain tax positions as interest expense and any penalties as other expense in its statements of operations and comprehensive loss. There was no interest or penalties accrued at December 31, 2016 and 2017. |
Segment Reporting and Signifi_4
Segment Reporting and Significant Customers | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Segment Reporting [Abstract] | ||
Segment Reporting and Significant Customers | Segment Reporting and Significant Customers Operating segments are defined as components of an enterprise for which separate discrete financial information is available and evaluated regularly by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. We globally manage the business within one reporting segment. Segment information is consistent with how management reviews the business, makes investing and resource allocation decisions and assesses operating performance. Revenue by geographic region is as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 United States $ 11,307 $ 6,547 $ 29,580 $ 15,922 Europe 1,747 724 4,454 2,688 Total revenue $ 13,054 $ 7,271 $ 34,034 $ 18,610 All of our long-lived assets are located in the United States. | 11. Segment Reporting and Significant Customers Operating segments are defined as components of an enterprise for which separate discrete financial information is available and evaluated regularly by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company globally manages the business within one reporting segment. Segment information is consistent with how management reviews the business, makes investing and resource allocation decisions and assesses operating performance. Revenue by geographic region are as follows: Year ended December 31, 2015 2016 2017 United States $ 6,132 $ 13,789 $ 24,293 Europe 1,880 2,638 4,274 Total revenue $ 8,012 $ 16,427 $ 28,567 All the Company’s long-lived assets are located in the United States. |
Loss Per Share_2
Loss Per Share | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Earnings Per Share [Abstract] | ||
Loss Per Share | Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because we have reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, convertible preferred stock warrants, convertible common stock warrants and common stock options were antidilutive in those periods. The following potentially dilutive securities outstanding at the end of the periods presented have been excluded from the computations of diluted shares outstanding because such securities have an antidilutive impact due to losses reported: September 30, 2018 2017 Convertible preferred stock outstanding — 12,111,706 Convertible preferred stock warrants — 65,434 Convertible common stock warrants 80,884 — Common stock options outstanding 2,198,130 2,074,994 Total 2,279,014 14,252,134 | 12. Loss Per Share Under the two- class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed. No such adjustment to earnings is made during periods with a net loss as the holders of the participating securities have no obligation to fund losses. Diluted net loss per common share is computed under the two- class method by using the weighted average number of shares of common stock outstanding plus, for periods with net income attributable to common stockholders, the potential dilutive effects of stock options and warrants. In addition, the Company analyzes the potential dilutive effect of the outstanding participating securities under the if- converted method when calculating diluted earnings per share in which it is assumed that the outstanding participating securities convert into common stock at the beginning of the period. The Company reports the more dilutive of the approaches (two- class or if- converted) as its diluted net income per share during the period. Due to the existence of net losses for the years ended December 31, 2015, 2016, and 2017, basic and diluted loss per share were the same, as the effect of potentially dilutive securities would have been anti- dilutive. The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an antidilutive impact due to losses reported: Year ended December 31, 2015 2016 2017 Convertible preferred stock outstanding 7,995,592 9,367,628 12,111,706 Convertible preferred stock warrants 367,598 394,587 423,784 Common stock options outstanding 1,541,163 1,497,511 2,071,616 9,904,353 11,259,726 14,607,106 |
Summary of Significant Accou_12
Summary of Significant Accounting Policies (Policies) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Accounting Policies [Abstract] | ||
Basis of Presentation | Basis of Presentation The accompanying condensed financial statements have been prepared without audit, pursuant to the rules and regulations of the SEC. The condensed financial statements may not include all disclosures required by U.S. GAAP; however, we believe that the disclosures are adequate to make the information presented not misleading. These unaudited condensed financial statements should be read in conjunction with the audited financial statements and the notes thereto for the fiscal year ended December 31, 2017 included in our audited consolidated financial statements for the year ended December 31, 2017 and the notes thereto for the year ended December 31, 2017 included in our final prospectus that forms a part of our Registration Statement on Form S-1 (File No. 333-224176), filed with the Securities and Exchange Commission ("SEC") pursuant to Rule 424(b)(4) on May 4, 2018 (the "Prospectus"). The condensed balance sheet at December 31, 2017 was derived from the audited financial statements. In the opinion of management, all adjustments, consisting of only normal recurring adjustments that are necessary to present fairly the financial position, results of operations, and cash flows for the interim periods, have been made. The results of operations for the interim periods are not necessarily indicative of the operating results for the full fiscal year or any future periods. Reverse Stock Split In connection with our initial public offering of common stock ("IPO"), our board of directors and stockholders approved a 1-for-6.650 reverse stock split of our common stock. The reverse stock split became effective on April 20, 2018. The par value of the common stock was not adjusted as a result of the reverse stock split. Adjustments corresponding to the reverse stock split were made to the ratio at which the convertible preferred stock will convert into common stock immediately prior to the closing of the IPO. Accordingly, all share and per-share amounts for all periods presented in these financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect the reverse stock split and adjustment of the conversion ratio of the convertible preferred stock. Initial Public Offering On May 7, 2018, we completed our IPO by issuing 7,762,500 shares of common stock, at an offering price of $16.00 per share, for net proceeds of approximately $112.0 million after deducting underwriting discounts and commissions and offering expenses payable by us. In connection with the IPO, our outstanding shares of convertible preferred stock were automatically converted into an aggregate of 12,111,706 shares of common stock, and our outstanding warrants to purchase shares of convertible preferred stock were automatically converted into warrants to purchase up to an aggregate of 100,558 shares of common stock, resulting in the reclassification of the related redeemable convertible preferred stock warrant liability of $0.9 million to additional paid-in capital ("APIC"). | Basis of Presentation The financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP). |
Use of Estimates | Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. We use significant judgment when making estimates related to the allowance for doubtful accounts, inventory reserves and the valuations of our common stock, share-based awards, and certain of our previously outstanding preferred stock warrants. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. | Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its allowance for doubtful accounts, inventory reserves and the valuations of its common stock, share‑based awards, and certain of its outstanding preferred stock warrants. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. |
JOBS Act Accounting Election | JOBS Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act of 2012 (the "JOBS Act"), we are eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. We have elected to take advantage of the extended transition period for adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. | JOBS Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act, the Company is eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. The Company has elected to take advantage of the extended transition period for adopting new or revised accounting standards that have different effective dates for public and private companies until such time as those standards apply to private companies. |
Cash and Cash Equivalents | Cash and Cash Equivalents We consider all highly liquid securities, readily convertible to cash, that mature within 90 days or less from the date of purchase to be cash equivalents. The carrying amount reported in the balance sheets for cash is cost, which approximates fair value. | Cash and Cash Equivalents The Company considers all highly liquid securities, readily convertible to cash, that mature within 90 days or less from the date of purchase to be cash equivalents. The carrying amount reported in the balance sheets for cash is cost, which approximates fair value. |
Short-term Investments | Short-Term Investments At September 30, 2018 and December 31, 2017 , our short-term investments consisted of commercial paper, corporate bonds, and U.S. government securities which are classified as available-for-sale and had maturities less than one year. Short-term investments are reported at their estimated fair market value which approximates cost. Any unrealized gains and losses are reported in accumulated other comprehensive loss. | Short‑term Investments The Company had no short-term investments at December 31, 2016. At December 31, 2017, the Company's short-term investments consisted of commercial paper and corporate bonds which are classified as available-for-sale and had maturities less than one year. Short-term investments are reported at their estimated fair market value which approximates cost at December 31, 2017. Any with unrealized gains and losses are reported in accumulated other comprehensive loss. |
Fair Value of Financial Instruments | Fair Value of Financial Instruments We measure certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents, short-term investments, and certain of our previously outstanding preferred stock warrants. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Observable inputs, such as quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Other inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs, including interest rate curves, foreign exchange rates, and credit ratings. Level 3—Unobservable inputs that are supported by little or no market activities, which would require us to develop our own assumptions. We use the methods and assumptions described below in determining the fair value of our financial instruments. Money market funds: Fair values of money market funds are based on quoted market prices in active markets. Commercial paper: Short-term, highly liquid investments are included as a Level 2 measurement in the tables below. Corporate bonds: Consists of notes, asset-backed securities and bonds with original maturities of less than one year and various yields. These are included as a Level 2 measurement in the tables below. U.S. government securities: Consists of U.S. Government treasury bills with original maturities of less than one year. These are included as a Level 1 measurement in the table below. The following tables sets forth by level within the fair value hierarchy our assets and liabilities that are reported at fair value as of September 30, 2018 and December 31, 2017 . As required by Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 820, Fair Value Measurement , assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of September 30, 2018 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 14,250 $ 14,250 $ — $ — Commercial paper 10,382 — 10,382 — Total cash equivalents 24,632 14,250 10,382 — Short-term investments: Commercial paper $ 47,631 $ — $ 47,631 $ — Corporate bonds 34,576 — 34,576 — U.S. government securities 11,907 11,907 — — Total short-term investments 94,114 11,907 82,207 — Total assets $ 118,746 $ 26,157 $ 92,589 $ — Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 $ — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 There were no transfers in and out of Level 1 and Level 2 fair value measurements during the periods ended September 30, 2018 and December 31, 2017 . The recurring Level 3 fair value measurements of our preferred stock warrant liabilities used the Black-Scholes option pricing model and value of the respective class of our convertible preferred stock (see Note 8 ), which was unobservable. All other assumptions included in the model are observable Level 1 inputs. The following table provides a reconciliation of the beginning and ending balances of our preferred stock warrant liabilities: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Balance at beginning of period $ — $ 57 $ 157 $ 53 Initial fair value of preferred stock warrants issued — — 103 4 Reclassified to equity — — (855 ) — Change in fair value of preferred stock warrants — — 595 — Balance at end of period $ — $ 57 $ — $ 57 Changes in the fair value of the preferred stock warrant liability were recorded in other expenses on the condensed statements of operations and comprehensive loss. In connection with the closing of the IPO in May 2018, warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock, resulting in the reclassification of the related convertible preferred stock warrant liability to APIC. | Fair Value of Financial Instruments The Company measures certain financial assets and liabilities at fair value on a recurring basis, including cash equivalents and certain of its outstanding preferred stock warrants. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market‑based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three‑tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Observable inputs, such as quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Other inputs that are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model‑based valuation techniques for which all significant inputs are observable in the market or can be derived from observable market data. Where applicable, these models project future cash flows and discount the future amounts to a present value using market‑based observable inputs, including interest rate curves, foreign exchange rates, and credit ratings. Level 3—Unobservable inputs that are supported by little or no market activities, which would require the Company to develop its own assumptions. The Company uses the methods and assumptions described below in determining the fair value of its financial instruments. Money market funds: Fair values of money market funds are based on quoted market prices in active markets. Commercial paper: Short‑term, highly liquid investments are included as a Level 2 measurement in the tables below. Corporate bonds: Consists of U.S. Government treasury bills, notes, and bonds with original maturities of less than one year and various yields. These are included as a Level 2 measurement in the tables below. The following tables sets forth by level within the fair value hierarchy the Company’s assets and liabilities that are reported at fair value as of December 31, 2016 and 2017. As required by Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 820, Fair Value Measurement , assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of December 31, 2016 Estimated Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ $ $ — $ — Liabilities Preferred stock warrants $ $ — $ — $ Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 There were no transfers in and out of Level 1 and Level 2 fair value measurements during the years ended December 31, 2016 and 2017. The recurring Level 3 fair value measurements of the Company's preferred stock warrant liabilities use the Black-Scholes option pricing model and value of the respective class of the Company's convertible preferred stock (see Note 7), which is unobservable. All other assumptions included in the model are observable Level 1 inputs. The following table provides a reconciliation of the beginning and ending balances of the Company's preferred stock warrant liabilities: Balance as of December 31, 2014 $ Initial fair value of preferred stock warrants issued 33 Change in fair value of preferred stock warrants 12 Balance as of December 31, 2015 248 Change in fair value of preferred stock warrants (195) Balance as of December 31, 2016 53 Initial fair value of preferred stock warrants issued Change in fair value of preferred stock warrants Balance as of December 31, 2017 $ 157 Changes in the fair value of the preferred stock warrant liability are recorded in other expenses on the statements of operations and comprehensive loss. |
Concentration of Credit Risk | Concentration of Credit Risk Financial instruments, which potentially subject us to concentrations of credit risk, consist principally of cash equivalents and accounts receivable. We believe that the credit risk in our accounts receivable is mitigated by our credit evaluation process, relatively short collection terms, and dispersion of our customer base. We generally do not require collateral, and losses on accounts receivable have historically been within management's expectations. Our investment policy limits investments to certain types of debt securities issued by the U.S. government and its agencies, corporations with investment-grade credit ratings, or commercial paper and money market funds issued by the highest quality financial and non-financial companies. We place restrictions on maturities and concentration by type and issuer. We are exposed to credit risk in the event of a default by the issuers of these securities to the extent recorded on the balance sheets. However, as of September 30, 2018 and December 31, 2017 , we limited our credit risk associated with cash equivalents by placing investments with banks we believe are highly creditworthy. | Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentrations of credit risk, consist principally of cash equivalents and accounts receivable. The Company believes that the credit risk in its accounts receivable is mitigated by its credit evaluation process, relatively short collection terms, and dispersion of its customer base. The Company generally does not require collateral, and losses on accounts receivable have historically been within management’s expectations. The Company’s investment policy limits investments to certain types of debt securities issued by the U.S. government and its agencies, corporations with investment‑grade credit ratings, or commercial paper and money market funds issued by the highest quality financial and non‑financial companies. The Company places restrictions on maturities and concentration by type and issuer. The Company is exposed to credit risk in the event of a default by the issuers of these securities to the extent recorded on the balance sheets. However, as of December 31, 2016 and 2017, the Company has limited its credit risk associated with its cash equivalents by placing its investments with banks it believes are highly creditworthy. |
Allowance for Doubtful Accounts | Allowance for Doubtful Accounts We record an allowance for doubtful accounts for accounts receivable deemed uncollectible. We evaluate the collectability of our accounts receivable based on known collection risks and historical experience. In circumstances where we are aware of a specific customer's inability to meet its financial obligations to us (e.g., bankruptcy filings, substantial downgrading of credit ratings), we record a specific allowance for bad debts against amounts due to reduce the carrying amount of accounts receivable to the amount we reasonably believe will be collected. | Allowance for Doubtful Accounts The Company records an allowance for doubtful accounts for accounts receivable deemed uncollectible. The Company evaluates the collectability of its accounts receivable based on known collection risks and historical experience. In circumstances where the Company is aware of a specific customer’s inability to meet its financial obligations to the Company (e.g., bankruptcy filings, substantial downgrading of credit ratings), the Company records a specific allowance for bad debts against amounts due to reduce the carrying amount of accounts receivable to the amount it reasonably believes will be collected. |
Inventories | Inventories Inventories are valued at the lower of cost or net realizable value, computed on a first-in, first out basis. We regularly review inventory quantities on-hand for excess and obsolete inventory and, when circumstances indicate, incur charges to write down inventories to their net realizable value. Our review of inventory for excess and obsolete quantities is based primarily on the estimated forecast of future product demand, product life cycles, including expiration of inventory prior to sale, and introduction of new products. | Inventories Inventories are valued at the lower of cost or net realizable value, computed on a first-in, first out basis. The Company regularly reviews inventory quantities on-hand for excess and obsolete inventory and, when circumstances indicate, incurs charges to write down inventories to their net realizable value. The Company's review of inventory for excess and obsolete quantities is based primarily on the estimated forecast of future product demand, product life cycles, including expiration of inventory prior to sale, and introduction of new products. The reserve for excess and obsolete inventory was $191 and $518 as of December 31, 2016 and 2017, respectively. |
Property and Equipment | Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. | Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight‑line method over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. |
Impairment of Long-lived Assets | Impairment of Long-lived Assets Long-lived assets consist primarily of property and equipment and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require that an asset be tested for possible impairment, we compare the undiscounted cash flows expected to be generated by the asset to the carrying amount of the asset. If the carrying amount of the asset is not recoverable on an undiscounted cash flow basis, we determine the fair value of the asset and recognize an impairment loss to the extent the carrying amount of the asset exceeds its fair value. We determine fair value using the income approach based on the present value of expected future cash flows or other appropriate measures of estimated fair value. Our cash flow assumptions consider historical and forecasted revenue and operating costs and other relevant factors. We did not record any impairment charges on long-lived assets during the nine months ended September 30, 2018 and 2017 . | Impairment of Long‑lived Assets Long‑lived assets consist primarily of property and equipment and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require that an asset be tested for possible impairment, the Company compares the undiscounted cash flows expected to be generated by the asset to the carrying amount of the asset. If the carrying amount of the asset is not recoverable on an undiscounted cash flow basis, the Company determines the fair value of the asset and recognizes an impairment loss to the extent the carrying amount of the asset exceeds its fair value. The Company determines fair value using the income approach based on the present value of expected future cash flows or other appropriate measures of estimated fair value. The Company’s cash flow assumptions consider historical and forecasted revenue and operating costs and other relevant factors. The Company did not record any impairment charges on long‑lived assets during the years ended December 31, 2015, 2016 and 2017. |
Revenue Recognition | Revenue Recognition We recognize revenue when persuasive evidence of an arrangement exists, product shipment has occurred, or there are no further obligations yet to be performed, pricing is fixed or determinable, and collection is reasonably assured. We make reasonable assumptions regarding the future collectability of amounts receivable from customers to determine whether the revenue recognition criteria have been met. Taxes assessed by a governmental authority that are directly imposed on revenue-producing transactions between a seller and a customer are not recorded as revenue. In general, our standard terms and conditions of sale do not allow for product returns. Sales returns have been limited to damaged product and have not been material. We expense shipping and handling costs as incurred and include them in the cost of goods sold. In those cases where shipping and handling costs are billed to customers, we classify the amounts billed as a component of cost of goods sold. | Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, product shipment has occurred, or there are no further obligations yet to be performed, pricing is fixed or determinable, and collection is reasonably assured. The Company makes reasonable assumptions regarding the future collectability of amounts receivable from customers to determine whether the revenue recognition criteria have been met. Taxes assessed by a governmental authority that are directly imposed on revenue‑producing transactions between a seller and a customer are not recorded as revenue. In general, the Company’s standard terms and conditions of sale do not allow for product returns. Sales returns have been limited to damaged product and have not been material. The Company expenses shipping and handling costs as incurred and includes them in the cost of goods sold. In those cases where shipping and handling costs are billed to customers, the Company classifies the amounts billed as a component of cost of goods sold. |
Cost of Goods Sold | Cost of Goods Sold Cost of goods sold consists primarily of manufacturing overhead costs, material costs, and direct labor. Overhead costs include the cost of material procurement, inventory control, facilities, equipment, and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs. | Cost of Goods Sold Cost of goods sold consists primarily of manufacturing overhead costs, material costs, and direct labor. Overhead costs include the cost of material procurement, inventory control, facilities, equipment, and operations supervision and management. Cost of goods sold also includes depreciation expense for production equipment and certain direct costs such as shipping costs. |
Research and Development | Research and Development Research and development expenses consist primarily of product development, clinical and regulatory affairs, consulting services, and other costs associated with products and technologies in development. These expenses include employee compensation, stock-based compensation, supplies, travel, and facility costs. Clinical expenses include clinical trial design, clinical site reimbursement, data management, travel expenses, and the cost of manufacturing products for clinical trials. | Research and Development Research and development expenses consist primarily of product development, clinical and regulatory affairs, consulting services, and other costs associated with products and technologies in development. These expenses include employee compensation, stock-based compensation, supplies, travel, and facility costs. Clinical expenses include clinical trial design, clinical site reimbursement, data management, travel expenses, and the cost of manufacturing products for clinical trials. |
Common Stock Valuation and Stock-Based Compensation | Common Stock Valuation and Stock-Based Compensation We maintain an equity incentive plan to provide long-term incentives for employees, consultants, and members of the board of directors. The plan allows for the issuance of non-statutory and incentive stock options to employees and non-statutory stock options to consultants and non-employee directors. We recognize equity-based compensation expense for awards of equity instruments to employees and non-employees based on the grant date fair value of those awards in accordance with FASB ASC Topic 718, Stock Compensation ("ASC 718"). ASC 718 requires all equity-based compensation awards to employees and nonemployee directors, including grants of restricted shares and stock options, to be recognized as expense in the statements of operations and comprehensive loss based on their grant date fair values. We estimate the fair value of stock options using the Black-Scholes option pricing model. We use the value of our common stock to determine the fair value of restricted shares. We account for restricted stock and common stock options issued to nonemployees under FASB ASC Topic 505-50, Equity-Based Payments to Non-Employees . As such, the value of such options is periodically remeasured and income or expense is recognized over their vesting terms. Compensation cost related to awards with service-based vesting schedules is recognized using the straight-line method. We determine the fair value of the restricted stock and common stock granted to nonemployees as either the fair value of the consideration received or the fair value of the equity instruments issued. We have not granted any share-based awards to our consultants. The Black-Scholes option pricing model requires the input of certain subjective assumptions, including (i) the expected share price volatility, (ii) the expected term of the award, (iii) the risk-free interest rate and (iv) the expected dividend yield. Due to the lack of a public market for the trading of our common stock and a lack of company-specific historical and implied volatility data, we have based our estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The group of representative companies have characteristics similar to us, including stage of product development and focus on the life science industry. We use the simplified method, which is the average of the final vesting tranche date and the contractual term, to calculate the expected term for options granted to employees as we do not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. For options granted to non-employees, we utilize the contractual term of the arrangement as the basis for the expected term assumption. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. We use an assumed dividend yield of zero as we have never paid dividends and have no current plans to pay any dividends on our common stock. We expense the fair value of our equity-based compensation awards granted to employees on a straight-line basis over the associated service period, which is generally the period in which the related services are received. We measure equity-based compensation awards granted to nonemployees at fair value as the awards vest and recognize the resulting value as compensation expense at each financial reporting period. We account for award forfeitures as they occur. | Common Stock Valuation and Stock‑Based Compensation The Company maintains an equity incentive plan to provide long-term incentives for employees, consultants, and members of the board of directors. The plan allows for the issuance of non-statutory and incentive stock options to employees and non-statutory stock options to consultants and non-employee directors. The Company recognizes equity‑based compensation expense for awards of equity instruments to employees and non‑employees based on the grant date fair value of those awards in accordance with FASB ASC Topic 718, Stock Compensation (ASC 718). ASC 718 requires all equity‑based compensation awards to employees and nonemployee directors, including grants of restricted shares and stock options, to be recognized as expense in the statements of operations and comprehensive loss based on their grant date fair values. The Company estimates the fair value of stock options using the Black‑Scholes option pricing model. The Company uses the value of its common stock to determine the fair value of restricted shares. The Company accounts for restricted stock and common stock options issued to nonemployees under FASB ASC Topic 505‑50, Equity‑Based Payments to Non‑Employees (ASC 505‑50). As such, the value of such options is periodically remeasured and income or expense is recognized over their vesting terms. Compensation cost related to awards with service‑based vesting schedules is recognized using the straight‑line method. The Company determines the fair value of the restricted stock and common stock granted to nonemployees as either the fair value of the consideration received or the fair value of the equity instruments issued. The Company has not granted any share‑based awards to its consultants. The Black‑Scholes option pricing model requires the input of certain subjective assumptions, including (i) the expected share price volatility, (ii) the expected term of the award, (iii) the risk‑free interest rate and (iv) the expected dividend yield. Due to the lack of a public market for the trading of the Company’s common stock and a lack of company‑specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The group of representative companies have characteristics similar to the Company, including stage of product development and focus on the life science industry. The Company uses the simplified method, which is the average of the final vesting tranche date and the contractual term, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. For options granted to non‑employees, the Company utilizes the contractual term of the arrangement as the basis for the expected term assumption. The risk‑free interest rate is based on a treasury instrument whose term is consistent with the expected term of the stock options. The Company uses an assumed dividend yield of zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock. The Company expenses the fair value of its equity‑based compensation awards granted to employees on a straight‑line basis over the associated service period, which is generally the period in which the related services are received. The Company measures equity‑based compensation awards granted to nonemployees at fair value as the awards vest and recognizes the resulting value as compensation expense at each financial reporting period. The Company accounts for award forfeitures as they occur. |
Advertising Expenses | Advertising Expenses We expense the costs of advertising, including promotional expenses, as incurred. | Advertising Expenses The Company expenses the costs of advertising, including promotional expenses, as incurred. Advertising expenses were $2.2 million, $3.4 million and $5.5 million during the years ended December 31, 2015, 2016, and 2017, respectively. |
Income Taxes | Income Taxes We account for income taxes using the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates that will be in effect when the differences are expected to reverse. Valuation allowances against deferred tax assets are established, when necessary, to reduce deferred tax assets to the amounts expected to be realized. As we have historically incurred operating losses, we have recorded a full valuation allowance against our net deferred tax assets, and there is no provision for income taxes. Our policy is to record interest and penalties expense related to uncertain tax positions as other expense in the statements of operations and comprehensive loss. | Income Taxes The Company accounts for income taxes using the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates that will be in effect when the differences are expected to reverse. Valuation allowances against deferred tax assets are established, when necessary, to reduce deferred tax assets to the amounts expected to be realized. As the Company has historically incurred operating losses, the Company has recorded a full valuation allowance against its net deferred tax assets, and there is no provision for income taxes. The Company's policy is to record interest and penalties expense related to uncertain tax positions as other expense in the statements of operations and comprehensive loss. |
Comprehensive Loss | Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on short-term investments classified as available-for-sale, if any. Accumulated other comprehensive loss is presented in the accompanying balance sheets as a component of stockholders' equity, if any. | Comprehensive Loss Comprehensive loss consists of net loss and changes in unrealized gains and losses on short‑term investments classified as available‑for‑sale, if any. Accumulated other comprehensive loss is presented in the accompanying balance sheets as a component of stockholders’ (deficit) equity. |
Loss Per Share | Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because we have reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, stock options and warrants were antidilutive in those periods. | Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Because the Company has reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods as all potentially dilutive shares consisting of convertible preferred stock, stock options and warrants were antidilutive in those periods. |
Recent Accounting Pronouncements | Recent Accounting Pronouncements We are an “emerging growth company” as defined by the JOBS Act. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act of 1933, as amended, (the "Securities Act"), for complying with new or revised accounting standards. Accordingly, an emerging growth company can selectively delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this exemption and, as a result, our financial statements may not be comparable to the financial statements of issuers that are required to comply with the effective dates for new or revised accounting standards that are applicable to public companies. Section 107 of the JOBS Act provides that we can elect to opt out of the extended transition period at any time, which election is irrevocable. In May 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers . The new section will replace Section 605, Revenue Recognition , and creates modifications to various other revenue accounting standards for specialized transactions and industries. The section is intended to conform revenue accounting principles with the concurrently issued International Financial Reporting Standards to reconcile previously differing treatment between U.S. practices and those of the rest of the world and to enhance disclosures related to disaggregated revenue information. The updated guidance is effective for interim and annual reporting periods beginning on or after December 15, 2018 for private companies and, therefore, us due to the JOBS Act exemption described above. We have commenced project planning for our implementation, which has included engaging an accounting firm to assist us. We have not yet made a determination on our transition method, nor have we determined whether this standard will have a material impact on our financial statements. We plan to complete our assessment of the impact of this standard during the fourth quarter of 2018. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes ("ASU 2015-17"). ASU 2015-17 is intended to reduce complexity surrounding the presentation of deferred taxes within the balance sheet. Specifically, ASU 2015-17 requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non-current on the balance sheet, effectively eliminating the requirement to allocate deferred taxes between current and non-current amounts. The new guidance does not permit companies to offset deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. This guidance was effective January 1, 2018 and did not significantly impact our financial statements and related disclosures. In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842), which supersedes the existing guidance for lease accounting, Leases (Topic 840). ASU 2016-02 requires lessees to recognize a lease liability and a right-of-use asset for all leases. Lessor accounting remains largely unchanged. The amendments in this ASU are effective for interim and annual periods beginning after December 15, 2019 for private companies; and, therefore, us due to the JOBS Act exemption described above. Early adoption is permitted for all entities. ASU 2016-02 requires a modified retrospective approach for all leases existing at, or entered into after, the date of initial adoption, with an option to elect to use certain transition relief. We plan to further evaluate the anticipated impact of the adoption of this ASU on our financial statements in future periods. In March 2016, the FASB issued No. 2016-9, Improvements to Employee Share-Based Payment Accounting ("ASU 2016-9"), which changes how companies will account for certain aspects of share-based payments to employees. As part of the new guidance, entities will be required to record the impact of income taxes arising from share-based compensation when awards vest or are settled within earnings as part of income tax expense rather than recorded as part of APIC and will eliminate the requirement that excess tax benefits be realized prior to recognition. Additionally, the guidance requires entities to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. Additionally, companies will be required to make an accounting policy election at the time of adoption of the new guidance to either account for forfeitures of share-based awards in a manner similar to today's requirements (i.e., estimating the number of awards expected to be forfeited at the grant date and adjusting the estimate when awards are actually forfeited), or recognizing forfeitures as they occur with no estimate of forfeitures determined at the grant date. Companies will also be able to set a maximum statutory tax rate as it pertains to share-based awards it net settles on behalf of its employees. This will provide companies a greater ability to retain equity-award accounting treatment. Entities will apply the provisions of ASU 2016-9 using a modified retrospective transition approach, with a cumulative-effect adjustment booked to retained earnings as of the beginning of the period of adoption. This guidance was effective for us on January 1, 2018 and did not significantly impact our financial statements and related disclosures. We have reviewed and considered all other recent accounting pronouncements and believe there are none that could potentially have a material impact on our business practices, financial condition, results of operations, or disclosures. | Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (ASU) No. 2014‑09, Revenue From Contracts With Customers (ASU 2014‑09), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014‑09 will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. In doing so, companies will need to use more judgment and make more estimates than under current guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price, and allocating the transaction price to each separate performance obligation. Under the original pronouncement, ASU 2014‑09 would have been effective for the Company’s annual reporting periods beginning January 1, 2018. In August 2015, the FASB issued ASU No. 2015‑14, which formally defers the effective date of the new revenue standard by one year. As a result, the updated revenue guidance will be effective for the Company’s annual reporting periods beginning January 1, 2019, and early adoption is permitted as of the original effective date contained within the original standard. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that ASU 2014‑09 will have on its financial statements and related disclosures. In July 2015, the FASB issued ASU 2015‑11 Simplifying the Measurement of Inventory , which is intended to narrow down the alternative methods available for valuing inventory. The new guidance does not apply to inventory currently measured using the last‑in‑first‑out or the retail inventory valuation methods. Under the new guidance, inventory valued using other methods, including the first‑in‑first‑out method, must be valued at the lower of cost or net realizable value. This guidance is effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2016. This guidance was effective January 1, 2017 and did not have a material impact on the Company’s financial position, results of operations and cash flows. In November 2015, the FASB issued ASU No. 2015‑17, Balance Sheet Classification of Deferred Taxes (ASU 2015‑17). ASU 2015‑17 is intended to reduce complexity surrounding the presentation of deferred taxes within the balance sheet. Specifically, ASU 2015‑17 requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as non‑current on the balance sheet, effectively eliminating the requirement to allocate deferred taxes between current and non‑current amounts. The new guidance does not permit companies to offset deferred tax liabilities from one jurisdiction against deferred tax assets of another jurisdiction. ASU 2015‑17 will be effective for the Company’s annual reporting periods beginning January 1, 2018, and can be applied on either a prospective or retrospective basis; early adoption is also permitted. The Company does not expect the ASU 2015‑17 to significantly impact its financial statements and related disclosures. In February 2016, the FASB issued ASU No. 2016‑02, Leases (ASU 2016‑02). ASU 2016‑02 will require entities that lease assets to recognize the rights and obligations associated with those leases on their balance sheets. The guidance will be effective for the Company’s annual reporting period beginning January 1, 2020, with early adoption permitted. The Company is evaluating the impact this standard will have on its financial statements and related disclosures. In March 2016, the FASB issued No. 2016‑09, Improvements to Employee Share‑Based Payment Accounting (ASU 2016‑09), which changes how companies will account for certain aspects of share‑based payments to employees. As part of the new guidance, entities will be required to record the impact of income taxes arising from share‑based compensation when awards vest or are settled within earnings as part of income tax expense rather than recorded as part of additional paid‑in capital (APIC) and will eliminate the requirement that excess tax benefits be realized prior to recognition. Additionally, the guidance requires entities to present excess tax benefits as an operating activity on the statement of cash flows rather than as a financing activity. Additionally, companies will be required to make an accounting policy election at the time of adoption of the new guidance to either account for forfeitures of share‑based awards in a manner similar to today’s requirements (i.e., estimating the number of awards expected to be forfeited at the grant date and adjusting the estimate when awards are actually forfeited), or recognizing forfeitures as they occur with no estimate of forfeitures determined at the grant date. Companies will also be able to set a maximum statutory tax rate as it pertains to share‑based awards it net settles on behalf of its employees. This will provide companies a greater ability to retain equity‑award accounting treatment. Entities will apply the provisions of ASU 2016‑09 using a modified retrospective transition approach, with a cumulative‑effect adjustment booked to retained earnings as of the beginning of the period of adoption. The guidance will be effective for the Company’s annual reporting periods beginning January 1, 2018, with early adoption permitted. The Company is evaluating the impact this standard will have on its financial statements and related disclosures. The Company has reviewed and considered all other recent accounting pronouncements and believes there are none that could potentially have a material impact on its business practices, financial condition, results of operations, or disclosures. |
Summary of Significant Accou_13
Summary of Significant Accounting Policies (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Accounting Policies [Abstract] | ||
Schedule of assets and liabilities measured at fair value on a recurring basis | The following tables summarize certain information for assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements as of September 30, 2018 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 14,250 $ 14,250 $ — $ — Commercial paper 10,382 — 10,382 — Total cash equivalents 24,632 14,250 10,382 — Short-term investments: Commercial paper $ 47,631 $ — $ 47,631 $ — Corporate bonds 34,576 — 34,576 — U.S. government securities 11,907 11,907 — — Total short-term investments 94,114 11,907 82,207 — Total assets $ 118,746 $ 26,157 $ 92,589 $ — Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 $ — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 | Fair Value Measurements as of December 31, 2016 Estimated Fair Value Level 1 Level 2 Level 3 Assets Money market funds $ $ $ — $ — Liabilities Preferred stock warrants $ $ — $ — $ Fair Value Measurements as of December 31, 2017 Estimated Fair Value Level 1 Level 2 Level 3 Assets Cash equivalents: Money market funds $ 6,446 $ 6,446 $ — $ — Commercial paper 1,099 — 1,099 — Total cash equivalents 7,545 6,446 1,099 — Short-term investments: Commercial paper $ 5,384 $ — $ 5,384 — Corporate bonds 1,804 — 1,804 — Total short-term investments 7,188 — 7,188 — Total assets $ 14,733 $ 6,446 $ 8,287 $ — Liabilities Preferred stock warrants $ 157 $ — $ — $ 157 |
Schedule of reconciliation of preferred stock warrant liabilities | The following table provides a reconciliation of the beginning and ending balances of our preferred stock warrant liabilities: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Balance at beginning of period $ — $ 57 $ 157 $ 53 Initial fair value of preferred stock warrants issued — — 103 4 Reclassified to equity — — (855 ) — Change in fair value of preferred stock warrants — — 595 — Balance at end of period $ — $ 57 $ — $ 57 Changes in the fair value of the preferred stock warrant liability were recorded in other expenses on the condensed statements of operations and comprehensive loss. In connection with the closing of the IPO in May 2018, warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock, resulting in the reclassification of the related convertible preferred stock warrant liability to APIC. | The following table provides a reconciliation of the beginning and ending balances of the Company's preferred stock warrant liabilities: Balance as of December 31, 2014 $ Initial fair value of preferred stock warrants issued 33 Change in fair value of preferred stock warrants 12 Balance as of December 31, 2015 248 Change in fair value of preferred stock warrants (195) Balance as of December 31, 2016 53 Initial fair value of preferred stock warrants issued Change in fair value of preferred stock warrants Balance as of December 31, 2017 $ 157 |
Composition of Certain Financ_7
Composition of Certain Financial Statement Items (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Composition of Certain Financial Statement Items | ||
Schedule of inventory | Inventories September 30, 2018 December 31, 2017 Raw materials $ 1,054 $ 1,323 Finished goods 2,021 2,347 Total inventories, net of reserves $ 3,075 $ 3,670 | December 31, 2016 2017 Raw materials $ 738 $ 1,323 Finished goods 2,617 2,347 $ 3,355 $ 3,670 |
Schedule of property and equipment | Property and Equipment September 30, 2018 December 31, 2017 Computer equipment and software $ 333 $ 351 Furniture and office equipment 148 137 Manufacturing equipment 857 1,108 Research and development equipment 30 30 Leasehold improvements 185 178 Property and equipment, cost 1,553 1,804 Less: accumulated depreciation and amortization (788 ) (810 ) Property and equipment, net $ 765 $ 994 | December 31, 2016 2017 Computer equipment and software $ 75 $ 351 Furniture and office equipment 84 137 Manufacturing equipment 1,329 1,108 Research and development equipment 34 30 Leasehold improvements 26 178 1,548 1,804 Less: accumulated depreciation and amortization (681) (810) $ 867 $ 994 |
Schedule of accrued expenses | Accrued Expenses September 30, 2018 December 31, 2017 Payroll and commissions payable $ 3,619 $ 2,871 Vacation 946 723 Other accrued expenses 397 438 Total accrued expenses $ 4,962 $ 4,032 | December 31, 2016 2017 Payroll and commissions payable $ 1,861 $ 2,871 Vacation 564 723 Other accrued expenses 279 438 $ 2,704 $ 4,032 |
Short-Term Investments (Tables)
Short-Term Investments (Tables) | 9 Months Ended |
Sep. 30, 2018 | |
Investments, Debt and Equity Securities [Abstract] | |
Short-term investments available-for-sale | Our short-term investments are classified as available-for-sale and consist of the following: September 30, 2018 Unrealized Cost Gains Losses Fair Value Commercial paper $ 47,631 $ — $ — $ 47,631 Corporate bonds 34,598 — 22 34,576 U.S. government securities 11,911 — 4 11,907 Short-term investments $ 94,140 $ — $ 26 $ 94,114 December 31, 2017 Unrealized Cost Gains Losses Fair Value Commercial paper $ 5,384 $ — $ — $ 5,384 Corporate bonds 1,804 — — 1,804 Short-term investments $ 7,188 $ — $ — $ 7,188 |
Long-Term Debt (Tables)_2
Long-Term Debt (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Long-term Debt, by Current and Noncurrent [Abstract] | ||
Schedule of expected future principal payments for the credit facility | Expected future principal payments for the credit facility are as follows: Year ending December 31 : 2018 (remaining) $ — 2019 — 2020 10,208 2021 12,250 2022 2,042 Total expected future principal payments $ 24,500 | Year ending December 31: 2018 $ — 2019 4,583 2020 5,500 2021 5,500 2022 917 $ 16,500 |
Commitments (Tables)_2
Commitments (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Commitments and Contingencies Disclosure [Abstract] | ||
Schedule of future minimum annual operating lease payments | Future minimum annual operating lease payments are as follows: Year ending December 31 : 2018 (remaining) $ 48 2019 1,043 2020 952 Total future operating lease payments $ 2,043 | Years ending December 31: 2018 $ 190 2019 48 Total $ 238 |
Stockholders' Equity (Tables)_2
Stockholders' Equity (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Stockholders' Equity Note [Abstract] | ||
Summary of the company's preferred stock and its terms | A summary of preferred stock and its terms as of December 31, 2017, is as follows: Series Shares Authorized Shares Issued and Outstanding Carrying Value Liquidation Preference per Share 8% Dividend per Share Conversion Price per Share A 5,375,507 5,375,507 $ 5,037 $ 1.00 $ 0.08 $ 6.65 B 8,706,909 8,706,909 15,913 1.84 0.15 9.91 C 14,091,589 13,829,906 14,949 1.07 0.09 7.12 D 5,683,292 5,683,292 6,043 1.07 0.09 7.12 E 15,373,091 15,267,175 39,848 2.62 0.21 15.16 F 27,664,232 27,372,261 37,316 1.37 0.11 9.11 Total 76,894,620 76,235,050 $ 119,106 | 2016 Shares Shares Issued and Carrying Series Authorized Outstanding Value A 5,375,507 5,375,507 $ 5,037 B 8,706,909 8,706,909 15,913 C 14,091,589 13,829,906 14,949 D 5,683,292 5,683,292 6,043 E 15,373,091 15,267,175 39,848 F 9,124,084 9,124,084 12,348 58,354,472 57,986,873 $ 94,138 2017 Shares Shares Issued and Carrying Series Authorized Outstanding Value A 5,375,507 5,375,507 $ 5,037 B 8,706,909 8,706,909 15,913 C 14,091,589 13,829,906 14,949 D 5,683,292 5,683,292 6,043 E 15,373,091 15,267,175 39,848 F 27,664,232 27,372,261 37,316 76,894,620 76,235,050 $ 119,106 A summary of the Company’s convertible preferred stock terms is as follows: Liquidation 8% Conversion Preference Dividend Price per Series per Share per Share Share A $ $ $ B C D E F |
Summary of preferred stock warrants issued under the company's original credit facility and subsequent amendments | As of May 7, 2018, the date of the closing of our IPO, the following preferred stock warrants issued under the original credit facility and subsequent amendments were outstanding and exercisable: Issuance Expiration Series Exercise Price Warrants Outstanding at May 7, 2018 Initial Value Fair Value at May 7, 2018 February 8, 2018 February 8, 2028 F $ 1.37 233,577 $ 103 $ 320 February 24, 2017 February 24, 2027 F 1.37 29,197 4 40 August 7, 2015 August 7, 2025 E 2.62 29,580 33 41 June 27, 2014 June 27, 2024 E 2.62 76,334 85 174 August 5, 2013 August 5, 2023 C 1.07 74,768 39 80 November 16, 2012 November 16, 2022 C 1.07 186,916 96 200 Total 630,372 $ 855 As of December 31, 2017, the following preferred stock warrants issued under the original credit facility and subsequent amendments were outstanding and exercisable: Issuance Expiration Series Exercise Price Warrants Outstanding at December 31, 2017 Initial Value Fair Value at December 31, 2017 February 24, 2017 February 24, 2027 F $ 1.37 29,197 $ 4 $ 13 August 7, 2015 August 7, 2025 E 2.62 29,580 33 8 June 27, 2014 June 27, 2024 E 2.62 76,334 85 21 August 5, 2013 August 5, 2023 C 1.07 74,768 39 33 November 16, 2012 November 16, 2022 C 1.07 186,916 96 82 Total 396,795 $ 157 | Warrants Fair Outstanding at Value at Dates Exercise December 31, Initial December 31, Issuance Expiration Series Price 2016 Value 2016 August 7, 2015 August 7, 2025 E $ 2.62 29,580 $ 33 $ 4 June 27, 2014 June 27, 2024 E 2.62 76,334 85 10 August 5, 2013 August 5, 2023 C 1.07 74,768 39 11 November 16, 2012 November 16, 2022 C 1.07 186,916 96 28 367,598 $ 53 Warrants Fair Outstanding at Value at Dates Exercise December 31, Initial December 31, Issuance Expiration Series Price 2017 Value 2017 February 24, 2017 February 24, 2027 F $ 1.37 29,197 $ 4 $ 13 August 7, 2015 August 7, 2025 E 2.62 29,580 33 8 June 27, 2014 June 27, 2024 E 2.62 76,334 85 21 August 5, 2013 August 5, 2023 C 1.07 74,768 39 33 November 16, 2012 November 16, 2022 C 1.07 186,916 96 82 396,795 $ 157 |
Stock Options (Tables)_2
Stock Options (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | ||
Summary of the company's stock option activity and related information | A summary of stock option activity and related information is as follows: Options Weighted Average Exercise Price Weighted average remaining contractual term (years) Aggregate intrinsic value (in thousands) Outstanding at December 31, 2017 2,071,616 $ 1.47 5.9 Granted 385,056 $ 15.04 Exercised (227,114 ) $ 1.90 Forfeited (31,428 ) $ 1.05 Outstanding at September 30, 2018 2,198,130 $ 3.80 6.8 $ 84,136 Exercisable at September 30, 2018 1,307,821 $ 1.58 5.4 $ 52,975 | Weighted Average Options Exercise Price Outstanding at December 31, 2014 1,534,672 $ 1.77 Granted 49,235 2.07 Exercised (21,545) 1.96 Forfeited (21,199) 1.15 Outstanding at December 31, 2015 1,541,163 1.77 Granted 120,277 1.65 Exercised (109,079) 1.74 Forfeited (54,850) 1.87 Outstanding at December 31, 2016 1,497,511 1.76 Granted 721,763 0.94 Exercised (127,122) 1.85 Forfeited (20,536) 1.88 Outstanding at December 31, 2017 2,071,616 1.47 Exercisable at December 31, 2017 1,236,255 1.75 |
Schedule of stock compensation recognized, before taxes | Total stock-based compensation recognized, before taxes, during the three and nine months ended September 30, 2018 and 2017 , is as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 General and administrative $ 326 $ 41 $ 592 $ 89 Sales and marketing 41 30 88 73 Research and development 5 10 16 27 Total stock-based compensation $ 372 $ 81 $ 696 $ 189 | Year ended December 31 2015 2016 2017 General and administrative $ 147 $ 108 $ 116 Sales and marketing 99 90 84 Research and development 59 50 43 $ 305 $ 248 $ 243 |
Summary of weighted average assumptions for fair value of options granted | The fair value of options granted to employees and non-employee directors during the nine months ended September 30, 2018 and 2017 was estimated as of the grant date using the Black-Scholes option pricing model using the following assumptions: Nine Months Ended September 30, 2018 2017 Expected life (years) 5.50 - 6.25 5.75 - 6.25 Expected volatility 37.5 - 49.8% 39.9 - 41.5% Risk-free interest rate 2.38 - 3.01% 1.88 - 2.32% Dividend yield 0.0% 0.0% Weighted average fair value $7.43 $0.40 | Year ended December 31, 2015 2016 2017 Expected life (years) Expected volatility % % % Risk-free interest rate 1.65 - 2.14 % 1.27 - 2.25 % 1.88 - 2.32 % Dividend yield 0.0 % 0.0 % 0.0 % Weighted average fair value $ 0.86 $ 0.47 $ 0.40 |
Segment Reporting and Signifi_5
Segment Reporting and Significant Customers (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Segment Reporting [Abstract] | ||
Schedule of revenue by geographic region | Revenue by geographic region is as follows: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 United States $ 11,307 $ 6,547 $ 29,580 $ 15,922 Europe 1,747 724 4,454 2,688 Total revenue $ 13,054 $ 7,271 $ 34,034 $ 18,610 | Year ended December 31, 2015 2016 2017 United States $ 6,132 $ 13,789 $ 24,293 Europe 1,880 2,638 4,274 Total revenue $ 8,012 $ 16,427 $ 28,567 |
Loss Per Share (Tables)_2
Loss Per Share (Tables) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Earnings Per Share [Abstract] | ||
Schedule of dilutive securities excluded from computations of diluted weighted average shares outstanding | The following potentially dilutive securities outstanding at the end of the periods presented have been excluded from the computations of diluted shares outstanding because such securities have an antidilutive impact due to losses reported: September 30, 2018 2017 Convertible preferred stock outstanding — 12,111,706 Convertible preferred stock warrants — 65,434 Convertible common stock warrants 80,884 — Common stock options outstanding 2,198,130 2,074,994 Total 2,279,014 14,252,134 | Year ended December 31, 2015 2016 2017 Convertible preferred stock outstanding 7,995,592 9,367,628 12,111,706 Convertible preferred stock warrants 367,598 394,587 423,784 Common stock options outstanding 1,541,163 1,497,511 2,071,616 9,904,353 11,259,726 14,607,106 |
Summary of Significant Accou_14
Summary of Significant Accounting Policies - Reverse Stock Split and Initial Public Offering (Details) $ / shares in Units, $ in Thousands | May 07, 2018USD ($)$ / sharesshares | Jun. 30, 2018USD ($) | May 31, 2018shares | Apr. 20, 2018 |
Reverse Stock Split | ||||
Reverse stock split ratio | 0.150 | |||
Initial Public Offering | ||||
Convertible preferred stock warrants reclassified to additional paid-in capital | $ | $ 855 | $ 855 | ||
Common Stock (in shares) | ||||
Initial Public Offering | ||||
Aggregate number of shares called by warrants (in shares) | 100,558 | |||
IPO | ||||
Initial Public Offering | ||||
Net proceeds from initial public offering | $ | $ 112,000 | |||
IPO | Common Stock (in shares) | ||||
Initial Public Offering | ||||
Shares issued during the period (in shares) | 7,762,500 | |||
Shares issue price (in dollars per share) | $ / shares | $ 16 | |||
Shares issued upon conversion (in shares) | 12,111,706 | 12,111,706 |
Summary of Significant Accou_15
Summary of Significant Accounting Policies - Short-term Investments and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands | 9 Months Ended | ||
Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Accumulated other comprehensive loss | $ (26) | $ 0 | $ 0 |
Realized gains | 400 | ||
Short-term investments: | |||
Total short-term investments | 94,114 | 7,188 | 0 |
Liabilities | |||
Preferred stock warrants | 0 | 157 | 53 |
Fair value of assets transferred from Level 1 to Level 2 | 0 | 0 | 0 |
Fair value of assets transferred from Level 2 to Level 1 | 0 | 0 | 0 |
Fair value of liabilities transferred from Level 1 to Level 2 | 0 | 0 | 0 |
Fair value of liabilities transferred from Level 2 to Level 1 | 0 | 0 | 0 |
Recurring basis | |||
Cash equivalents: | |||
Money market funds | 14,250 | 6,446 | 5,084 |
Commercial paper | 10,382 | 1,099 | |
Total cash equivalents | 24,632 | 7,545 | |
Short-term investments: | |||
Commercial paper | 47,631 | 5,384 | |
Corporate bonds | 34,576 | 1,804 | |
U.S. government securities | 11,907 | ||
Total short-term investments | 94,114 | 7,188 | |
Total assets | 118,746 | 14,733 | |
Liabilities | |||
Preferred stock warrants | 157 | 53 | |
Level 1 | Recurring basis | |||
Cash equivalents: | |||
Money market funds | 14,250 | 6,446 | 5,084 |
Commercial paper | 0 | 0 | |
Total cash equivalents | 14,250 | 6,446 | |
Short-term investments: | |||
Commercial paper | 0 | 0 | |
Corporate bonds | 0 | 0 | |
U.S. government securities | 11,907 | ||
Total short-term investments | 11,907 | 0 | |
Total assets | 26,157 | 6,446 | |
Liabilities | |||
Preferred stock warrants | 0 | ||
Level 2 | Recurring basis | |||
Cash equivalents: | |||
Money market funds | 0 | 0 | |
Commercial paper | 10,382 | 1,099 | |
Total cash equivalents | 10,382 | 1,099 | |
Short-term investments: | |||
Commercial paper | 47,631 | 5,384 | |
Corporate bonds | 34,576 | 1,804 | |
U.S. government securities | 0 | ||
Total short-term investments | 82,207 | 7,188 | |
Total assets | 92,589 | 8,287 | |
Liabilities | |||
Preferred stock warrants | 0 | ||
Level 3 | Recurring basis | |||
Cash equivalents: | |||
Money market funds | 0 | 0 | |
Commercial paper | 0 | 0 | |
Total cash equivalents | 0 | 0 | |
Short-term investments: | |||
Commercial paper | 0 | 0 | |
Corporate bonds | 0 | 0 | |
U.S. government securities | 0 | ||
Total short-term investments | 0 | 0 | |
Total assets | $ 0 | 0 | |
Liabilities | |||
Preferred stock warrants | $ 157 | $ 53 |
Summary of Significant Accou_16
Summary of Significant Accounting Policies - Reconciliation of Preferred Stock Warrant Liabilities (Details) - Preferred stock warrant - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Reconciliation of preferred stock warrant liabilities: | |||||
Balance at beginning of period | $ 157 | $ 53 | $ 53 | $ 248 | $ 203 |
Initial fair value of preferred stock warrants issued | 103 | 4 | 4 | 33 | |
Reclassified to equity | (855) | 0 | |||
Change in fair value of preferred stock warrants | $ 595 | 0 | 100 | (195) | 12 |
Balance at end of period | $ 57 | $ 157 | $ 53 | $ 248 |
Summary of Significant Accou_17
Summary of Significant Accounting Policies - Inventories (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Accounting Policies [Abstract] | |||
Reserve for excess and obsolete inventory | $ 813 | $ 518 | $ 191 |
Summary of Significant Accou_18
Summary of Significant Accounting Policies - Property and Equipment (Details) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Minimum | ||
Property and Equipment | ||
Estimated useful lives | 3 years | 3 years |
Maximum | ||
Property and Equipment | ||
Estimated useful lives | 7 years | 7 years |
Summary of Significant Accou_19
Summary of Significant Accounting Policies - Stock Based Compensation (Details) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2018 | Dec. 31, 2017 | |
Accounting Policies [Abstract] | ||
Dividend yield | 0.00% | 0.00% |
Summary of Significant Accou_20
Summary of Significant Accounting Policies - Advertising Expenses (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Advertising Expenses | |||||
Advertising expenses | $ 5.8 | $ 3.7 | $ 5.5 | $ 3.4 | $ 2.2 |
Summary of Significant Accou_21
Summary of Significant Accounting Policies - Income Taxes (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | ||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | |
Income Taxes | ||||
Provision for income taxes | $ 0 | $ 0 | $ 0 | $ 0 |
Composition of Certain Financ_8
Composition of Certain Financial Statement Items - Inventories (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Composition of Certain Financial Statement Items | |||
Raw materials | $ 1,054 | $ 1,323 | $ 738 |
Finished goods | 2,021 | 2,347 | 2,617 |
Total inventories, net of reserves | $ 3,075 | $ 3,670 | $ 3,355 |
Composition of Certain Financ_9
Composition of Certain Financial Statement Items - Property and Equipment (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Property and Equipment | |||||
Property and equipment, gross | $ 1,553 | $ 1,804 | $ 1,548 | ||
Less: accumulated depreciation | (788) | (810) | (681) | ||
Property and equipment, net | 765 | 994 | 867 | ||
Depreciation and amortization expenses | 288 | $ 174 | 285 | 103 | $ 120 |
Computer equipment and software | |||||
Property and Equipment | |||||
Property and equipment, gross | 333 | 351 | 75 | ||
Furniture and office equipment | |||||
Property and Equipment | |||||
Property and equipment, gross | 148 | 137 | 84 | ||
Manufacturing equipment | |||||
Property and Equipment | |||||
Property and equipment, gross | 857 | 1,108 | 1,329 | ||
Research and development equipment | |||||
Property and Equipment | |||||
Property and equipment, gross | 30 | 30 | 34 | ||
Leasehold improvements | |||||
Property and Equipment | |||||
Property and equipment, gross | $ 185 | $ 178 | $ 26 |
Composition of Certain Finan_10
Composition of Certain Financial Statement Items - Accrued Expenses (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Composition of Certain Financial Statement Items | |||
Payroll and commissions payable | $ 3,619 | $ 2,871 | $ 1,861 |
Vacation | 946 | 723 | 564 |
Other accrued expenses | 397 | 438 | 279 |
Total accrued expenses | $ 4,962 | $ 4,032 | $ 2,704 |
Short-Term Investments (Details
Short-Term Investments (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017 |
Debt Securities, Available-for-sale [Line Items] | ||
Cost | $ 94,140 | $ 7,188 |
Unrealized Gains | 0 | 0 |
Unrealized Losses | 26 | 0 |
Fair Value | 94,114 | 7,188 |
Investments with maturity greater than one year | 0 | 0 |
Commercial paper | ||
Debt Securities, Available-for-sale [Line Items] | ||
Cost | 47,631 | 5,384 |
Unrealized Gains | 0 | 0 |
Unrealized Losses | 0 | 0 |
Fair Value | 47,631 | 5,384 |
Corporate bonds | ||
Debt Securities, Available-for-sale [Line Items] | ||
Cost | 34,598 | 1,804 |
Unrealized Gains | 0 | 0 |
Unrealized Losses | 22 | 0 |
Fair Value | 34,576 | $ 1,804 |
U.S. government securities | ||
Debt Securities, Available-for-sale [Line Items] | ||
Cost | 11,911 | |
Unrealized Gains | 0 | |
Unrealized Losses | 4 | |
Fair Value | $ 11,907 |
Long-Term Debt (Details)_2
Long-Term Debt (Details) - USD ($) $ / shares in Units, $ in Thousands | Feb. 07, 2018 | Feb. 28, 2017 | Aug. 31, 2015 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2018 |
Credit Facility | |||||||
Outstanding credit facility amount | $ 16,500 | ||||||
Debt issuance costs | $ 72 | $ 0 | $ 0 | $ 72 | |||
Expected future principal payments | |||||||
2018 (remaining) | $ 0 | ||||||
2,019 | 4,583 | 0 | |||||
2,020 | 5,500 | 10,208 | |||||
2,021 | 5,500 | 12,250 | |||||
2,022 | 917 | 2,042 | |||||
Total expected future principal payments | $ 16,500 | $ 24,500 | |||||
Series F convertible preferred stock (in shares) | |||||||
Credit Facility | |||||||
Aggregate number of shares called by warrants (in shares) | 233,577 | 29,197 | |||||
Period of warrants | 10 years | 10 years | |||||
Exercise price (in dollars per share) | $ 1.37 | $ 1.37 | $ 1.37 | $ 1.37 | |||
Term A loan facility | |||||||
Credit Facility | |||||||
Maximum borrowing amount under credit facility | 15,500 | ||||||
Outstanding credit facility amount | $ 15,500 | ||||||
Fixed interest rate on credit facility | 7.95% | ||||||
Variable interest rate on credit facility | 6.90% | ||||||
Additional borrowing amount under credit facility | $ 1,000 | ||||||
Net proceeds from credit facility | $ 500 | ||||||
Term A loan facility | On or after February 24, 2018 but prior to February 24, 2019/On or after February 7, 2019 but prior to February 7, 2020 | |||||||
Credit Facility | |||||||
Prepayment fee | 1.50% | ||||||
Term A loan facility | On or after February 24, 2019/On or after February 7, 2020 | |||||||
Credit Facility | |||||||
Prepayment fee | 1.00% | ||||||
Term A loan facility | Prior to February 24, 2018/Prior to February 7, 2019 | |||||||
Credit Facility | |||||||
Prepayment fee | 2.50% | ||||||
Original credit facility | |||||||
Credit Facility | |||||||
Outstanding credit facility amount | $ 12,000 | ||||||
Term B loan facility | |||||||
Credit Facility | |||||||
Outstanding credit facility amount | $ 24,500 | $ 9,000 | |||||
Fixed interest rate on credit facility | 7.95% | 7.95% | |||||
Additional borrowing amount under credit facility | $ 8,000 | ||||||
Net proceeds from credit facility | $ 8,000 | ||||||
Trailing period revenue | 12 months | 12 months | |||||
Minimum amount of revenue for interest only period | $ 25,000 | $ 25,000 | |||||
Final payment fee | 5.00% | ||||||
Increase in interest rate in default | 5.00% | 5.00% | |||||
Term B loan facility | On or after February 24, 2018 but prior to February 24, 2019/On or after February 7, 2019 but prior to February 7, 2020 | |||||||
Credit Facility | |||||||
Prepayment fee | 1.50% | ||||||
Term B loan facility | On or after February 24, 2019/On or after February 7, 2020 | |||||||
Credit Facility | |||||||
Prepayment fee | 1.00% | ||||||
Term B loan facility | Prior to February 24, 2018/Prior to February 7, 2019 | |||||||
Credit Facility | |||||||
Prepayment fee | 2.50% | ||||||
Term B loan facility | LIBOR | |||||||
Credit Facility | |||||||
Variable interest rate on credit facility | 6.90% | ||||||
Term B loan facility | Minimum | |||||||
Credit Facility | |||||||
Outstanding credit facility amount | $ 3,500 | ||||||
Term B loan facility | Maximum | |||||||
Credit Facility | |||||||
Outstanding credit facility amount | $ 10,000 |
Commitments - Operating Lease_2
Commitments - Operating Lease (Details) ft² in Thousands, $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018USD ($)ft² | Sep. 30, 2017USD ($) | Dec. 31, 2017USD ($) | Dec. 31, 2016USD ($) | Dec. 31, 2015USD ($) | |
Future minimum annual operating lease payments | |||||
2018 (remaining) | $ 48 | ||||
2,019 | 1,043 | $ 48 | |||
2,020 | 952 | ||||
Total future operating lease payments | 2,043 | 238 | |||
Rent expense | |||||
Rent expense | $ 100 | $ 100 | $ 184 | $ 127 | $ 123 |
Office Space Sublease | |||||
Operating lease sublease land agreement | ft² | 44 |
Commitments - Purchase Commit_2
Commitments - Purchase Commitments (Details) - USD ($) $ in Millions | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Purchase Commitments | |||
Commitments to suppliers for inventory purchases | $ 16.2 | $ 9 | $ 6.1 |
Medtronic | |||
Purchase Commitments | |||
Commitments to suppliers for inventory purchases | $ 0.1 | $ 0.4 | $ 0.6 |
Stockholders' Equity - Authoriz
Stockholders' Equity - Authorized Shares (Details) - $ / shares | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 |
Stockholders' Equity Note [Abstract] | |||
Total shares authorized (in shares) | 210,000,000 | 186,894,620 | |
Common stock, authorized (in shares) | 200,000,000 | 110,000,000 | 85,000,000 |
Preferred shares, authorized (in shares) | 10,000,000 | 76,894,620 | 58,354,472 |
Common stock, par value (in dollars per share) | $ 0.001 | $ 0.001 | $ 0.001 |
Preferred stock, par value (in dollars per share) | $ 0.001 | $ 0.001 | $ 0.001 |
Stockholders' Equity - Preferre
Stockholders' Equity - Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands | 1 Months Ended | 12 Months Ended | |||
May 31, 2018 | Dec. 31, 2017 | Sep. 30, 2018 | May 07, 2018 | Dec. 31, 2016 | |
Stockholders' Equity | |||||
Shares Authorized (in shares) | 76,894,620 | 10,000,000 | 58,354,472 | ||
Shares Issued (in shares) | 76,235,050 | 0 | 57,986,873 | ||
Shares Outstanding (in shares) | 76,235,050 | 0 | 57,986,873 | ||
Carrying Value | $ 119,106 | $ 0 | $ 94,138 | ||
Dividend rate | 8.00% | ||||
Convertible preferred stock outstanding (in shares) | |||||
Stockholders' Equity | |||||
Shares Authorized (in shares) | 76,894,620 | 58,354,472 | |||
Shares Issued (in shares) | 76,235,050 | 57,986,873 | |||
Shares Outstanding (in shares) | 76,235,050 | 57,986,873 | |||
Carrying Value | $ 119,106 | $ 94,138 | |||
Series A convertible preferred stock (in shares) | |||||
Stockholders' Equity | |||||
Shares Authorized (in shares) | 5,375,507 | 5,375,507 | |||
Shares Issued (in shares) | 5,375,507 | 5,375,507 | |||
Shares Outstanding (in shares) | 5,375,507 | 5,375,507 | |||
Carrying Value | $ 5,037 | $ 5,037 | |||
Liquidation Preference per Share (in dollars per share) | $ 1 | ||||
8% Dividend per Share (in dollars per share) | 0.08 | ||||
Conversion Price per Share (in dollars per share) | $ 6.65 | ||||
Series B convertible preferred stock (in shares) | |||||
Stockholders' Equity | |||||
Shares Authorized (in shares) | 8,706,909 | 8,706,909 | |||
Shares Issued (in shares) | 8,706,909 | 8,706,909 | |||
Shares Outstanding (in shares) | 8,706,909 | 8,706,909 | |||
Carrying Value | $ 15,913 | $ 15,913 | |||
Liquidation Preference per Share (in dollars per share) | $ 1.84 | ||||
8% Dividend per Share (in dollars per share) | 0.15 | ||||
Conversion Price per Share (in dollars per share) | $ 9.91 | ||||
Series C convertible preferred stock (in shares) | |||||
Stockholders' Equity | |||||
Shares Authorized (in shares) | 14,091,589 | 14,091,589 | |||
Shares Issued (in shares) | 13,829,906 | 13,829,906 | |||
Shares Outstanding (in shares) | 13,829,906 | 13,829,906 | |||
Carrying Value | $ 14,949 | $ 14,949 | |||
Liquidation Preference per Share (in dollars per share) | $ 1.07 | ||||
8% Dividend per Share (in dollars per share) | 0.09 | ||||
Conversion Price per Share (in dollars per share) | $ 7.12 | ||||
Series D convertible preferred stock (in shares) | |||||
Stockholders' Equity | |||||
Shares Authorized (in shares) | 5,683,292 | 5,683,292 | |||
Shares Issued (in shares) | 5,683,292 | 5,683,292 | |||
Shares Outstanding (in shares) | 5,683,292 | 5,683,292 | |||
Carrying Value | $ 6,043 | $ 6,043 | |||
Liquidation Preference per Share (in dollars per share) | $ 1.07 | ||||
8% Dividend per Share (in dollars per share) | 0.09 | ||||
Conversion Price per Share (in dollars per share) | $ 7.12 | ||||
Series E convertible preferred stock (in shares) | |||||
Stockholders' Equity | |||||
Shares Authorized (in shares) | 15,373,091 | 15,373,091 | |||
Shares Issued (in shares) | 15,267,175 | 15,267,175 | |||
Shares Outstanding (in shares) | 15,267,175 | 15,267,175 | |||
Carrying Value | $ 39,848 | $ 39,848 | |||
Liquidation Preference per Share (in dollars per share) | $ 2.62 | ||||
8% Dividend per Share (in dollars per share) | 0.21 | ||||
Conversion Price per Share (in dollars per share) | $ 15.16 | ||||
Series F convertible preferred stock (in shares) | |||||
Stockholders' Equity | |||||
Shares Authorized (in shares) | 27,664,232 | 9,124,084 | |||
Shares Issued (in shares) | 27,372,261 | 9,124,084 | |||
Shares Outstanding (in shares) | 27,372,261 | 9,124,084 | |||
Carrying Value | $ 37,316 | $ 12,348 | |||
Liquidation Preference per Share (in dollars per share) | $ 1.37 | ||||
8% Dividend per Share (in dollars per share) | 0.11 | ||||
Conversion Price per Share (in dollars per share) | $ 9.11 | ||||
IPO | |||||
Stockholders' Equity | |||||
Shares Issued (in shares) | 0 | ||||
IPO | Convertible preferred stock outstanding (in shares) | |||||
Stockholders' Equity | |||||
Number of shares converted (in shares) | 76,235,050 | ||||
Value of shares converted | $ 119,100 | ||||
IPO | Common Stock (in shares) | |||||
Stockholders' Equity | |||||
Shares issued upon conversion (in shares) | 12,111,706 | 12,111,706 |
Stockholders' Equity - Prefer_2
Stockholders' Equity - Preferred Stock Warrants (Details) - USD ($) $ / shares in Units, $ in Thousands | Sep. 10, 2018 | May 07, 2018 | Feb. 08, 2018 | Feb. 24, 2017 | Aug. 07, 2015 | Aug. 05, 2013 | Jun. 30, 2014 | Jun. 30, 2018 | Dec. 31, 2017 | Sep. 30, 2018 | Feb. 07, 2018 | Feb. 28, 2017 | Dec. 31, 2016 | Jun. 27, 2014 | Nov. 16, 2012 |
Preferred Stock Warrants | |||||||||||||||
Convertible preferred stock warrants reclassified to additional paid-in capital | $ 855 | $ 855 | |||||||||||||
Convertible preferred stock outstanding (in shares) | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Warrants outstanding (in shares) | 630,372 | 396,795 | 367,598 | ||||||||||||
Fair Value | $ 855 | $ 157 | $ 53 | ||||||||||||
Number of warrants converted (in shares) | 630,372 | ||||||||||||||
Warrants, weighted average exercise price (in dollars per share) | $ 1.46 | ||||||||||||||
Series C convertible preferred stock (in shares) | Warrants Issued on August 5, 2013 | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Warrants issued (in shares) | 74,768 | ||||||||||||||
Term of warrants | 10 years | ||||||||||||||
Value of each warrant (in dollars per share) | $ 0.525 | ||||||||||||||
Exercise price (in dollars per share) | $ 1.07 | $ 1.07 | $ 1.07 | $ 1.07 | |||||||||||
Warrants outstanding (in shares) | 74,768 | 74,768 | 74,768 | ||||||||||||
Initial Value | $ 39 | $ 39 | |||||||||||||
Fair Value | $ 80 | $ 33 | $ 11 | ||||||||||||
Series C convertible preferred stock (in shares) | Warrants Issued on November 16, 2012 | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Exercise price (in dollars per share) | $ 1.07 | $ 1.07 | $ 1.07 | ||||||||||||
Warrants outstanding (in shares) | 186,916 | 186,916 | 186,916 | ||||||||||||
Initial Value | $ 96 | $ 96 | |||||||||||||
Fair Value | $ 200 | $ 82 | $ 28 | ||||||||||||
Series E convertible preferred stock (in shares) | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Warrants issued (in shares) | 76,334 | ||||||||||||||
Term of warrants | 10 years | ||||||||||||||
Value of each warrant (in dollars per share) | $ 1.11 | ||||||||||||||
Exercise price (in dollars per share) | $ 2.62 | ||||||||||||||
Initial Value | $ 85 | ||||||||||||||
Series E convertible preferred stock (in shares) | Warrants Issued on August 7, 2015 | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Warrants issued (in shares) | 29,580 | ||||||||||||||
Term of warrants | 10 years | ||||||||||||||
Value of each warrant (in dollars per share) | $ 1.13 | ||||||||||||||
Exercise price (in dollars per share) | $ 2.62 | $ 2.62 | $ 2.62 | $ 2.62 | |||||||||||
Warrants outstanding (in shares) | 29,580 | 29,580 | 29,580 | ||||||||||||
Initial Value | $ 33 | $ 33 | |||||||||||||
Fair Value | $ 41 | $ 8 | $ 4 | ||||||||||||
Series E convertible preferred stock (in shares) | Warrants Issued on June 27, 2014 | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Exercise price (in dollars per share) | $ 2.62 | $ 2.62 | $ 2.62 | ||||||||||||
Warrants outstanding (in shares) | 76,334 | 76,334 | 76,334 | ||||||||||||
Initial Value | $ 85 | $ 85 | |||||||||||||
Fair Value | $ 174 | $ 21 | $ 10 | ||||||||||||
Series F convertible preferred stock (in shares) | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Aggregate number of shares called by warrants (in shares) | 233,577 | 29,197 | |||||||||||||
Exercise price (in dollars per share) | $ 1.37 | $ 1.37 | $ 1.37 | $ 1.37 | |||||||||||
Adjusted warrants due to dilutive issuance (in shares) | 56,569 | 56,569 | |||||||||||||
Series F convertible preferred stock (in shares) | Warrants Issued on February 8, 2018 | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Warrants issued (in shares) | 233,577 | ||||||||||||||
Term of warrants | 10 years | ||||||||||||||
Value of each warrant (in dollars per share) | $ 0.44 | ||||||||||||||
Exercise price (in dollars per share) | $ 1.37 | $ 1.37 | |||||||||||||
Warrants outstanding (in shares) | 233,577 | ||||||||||||||
Initial Value | $ 103 | ||||||||||||||
Fair Value | $ 320 | ||||||||||||||
Series F convertible preferred stock (in shares) | Warrants Issued on February 24, 2017 | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Warrants issued (in shares) | 29,197 | ||||||||||||||
Term of warrants | 10 years | ||||||||||||||
Value of each warrant (in dollars per share) | $ 0.13 | ||||||||||||||
Exercise price (in dollars per share) | $ 1.37 | $ 1.37 | $ 1.37 | ||||||||||||
Warrants outstanding (in shares) | 29,197 | 29,197 | |||||||||||||
Initial Value | $ 4 | ||||||||||||||
Fair Value | $ 40 | $ 13 | |||||||||||||
Common Stock (in shares) | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Aggregate number of shares called by warrants (in shares) | 100,558 | ||||||||||||||
Warrants, weighted average exercise price (in dollars per share) | $ 9.38 | ||||||||||||||
Common Stock (in shares) | Warrants Issued on September 10, 2018 | |||||||||||||||
Preferred Stock Warrants | |||||||||||||||
Warrants issued (in shares) | 17,050 | ||||||||||||||
Number of warrants converted (in shares) | 19,674 |
Stock Options - 2018 Plan (Deta
Stock Options - 2018 Plan (Details) - $ / shares | 9 Months Ended | 12 Months Ended | ||
Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Stock Options | ||||
Fixed exercise price of options, minimum (in dollars per share) | $ 2.80 | $ 0.94 | ||
Fixed exercise price of options, maximum (in dollars per share) | 54.99 | 6.65 | ||
Options granted exercise prices (in dollars per share) | $ 15.04 | $ 0.94 | $ 1.65 | $ 2.07 |
Options | ||||
Stock Options | ||||
Service period | 4 years | 4 years | ||
Contractual life of stock options | 10 years | 10 years | ||
Options | Directors | ||||
Stock Options | ||||
Service period | 1 year | |||
Vesting period | 1 year | |||
Options | Vesting after first year of service | ||||
Stock Options | ||||
Percentage of shares to vest | 25.00% | 25.00% | ||
Options | Vesting in years two through four | ||||
Stock Options | ||||
Vesting period | 36 months | 36 months | ||
Stock Incentive Plan 2018 | ||||
Stock Options | ||||
Number of shares reserved for issuance (in shares) | 1,386,809 | |||
Number of shares available for issuance (in shares) | 1,036,392 |
Stock Options - Stock Option _2
Stock Options - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands | Dec. 31, 2017 | Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2017 |
Options | ||||||
Outstanding at beginning of the year (in shares) | 2,071,616 | 1,497,511 | 1,541,163 | 1,534,672 | ||
Granted (in shares) | 385,056 | 721,763 | 120,277 | 49,235 | ||
Exercised (in shares) | (227,114) | (127,122) | (109,079) | (21,545) | ||
Forfeited (in shares) | (31,428) | (20,536) | (54,850) | (21,199) | ||
Outstanding at ending of the year (in shares) | 2,071,616 | 2,198,130 | 2,071,616 | 1,497,511 | 1,541,163 | |
Exercisable (in shares) | 1,236,255 | 1,307,821 | 1,236,255 | |||
Weighted Average Exercise Price | ||||||
Outstanding, beginning of the period (in dollars per share) | $ 1.47 | $ 1.76 | $ 1.77 | $ 1.77 | ||
Granted (in dollars per share) | 15.04 | 0.94 | 1.65 | 2.07 | ||
Exercised (in dollars per share) | 1.90 | 1.85 | 1.74 | 1.96 | ||
Forfeited (in dollars per share) | 1.05 | 1.88 | 1.87 | 1.15 | ||
Outstanding, end of the period (in dollars per share) | $ 1.47 | 3.80 | 1.47 | $ 1.76 | $ 1.77 | |
Exercisable (in dollars per share) | $ 1.75 | $ 1.58 | $ 1.75 | |||
Weighted average remaining contractual term | ||||||
Outstanding | 5 years 10 months 24 days | 6 years 10 months | 5 years 10 months 24 days | 5 years 9 months 18 days | 6 years 7 months 6 days | |
Exercisable | 5 years 4 months 22 days | |||||
Aggregate intrinsic value | ||||||
Outstanding | $ 84,136 | |||||
Exercisable | $ 52,975 |
Stock Options - Stock-Based Com
Stock Options - Stock-Based Compensation (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Stock Options | |||||
Total stock-based compensation | $ 696 | $ 189 | $ 243 | $ 248 | $ 305 |
Unearned stock-based compensation | $ 2,400 | $ 318,000 | |||
Weighted average recognition period | 2 years 7 months 12 days | 3 years | |||
General and administrative | |||||
Stock Options | |||||
Total stock-based compensation | $ 592 | 89 | $ 116 | 108 | 147 |
Sales and marketing | |||||
Stock Options | |||||
Total stock-based compensation | 88 | 73 | 84 | 90 | 99 |
Research and development | |||||
Stock Options | |||||
Total stock-based compensation | $ 16 | $ 27 | $ 43 | $ 50 | $ 59 |
Stock Options - Assumptions Use
Stock Options - Assumptions Used to Calculate Fair Value of Options (Details) - $ / shares | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Weighted average assumptions | |||||
Dividend yield | 0.00% | 0.00% | |||
Options | |||||
Weighted average assumptions | |||||
Dividend yield | 0.00% | 0.00% | 0.00% | 0.00% | 0.00% |
Weighted average fair value (in dollars per share) | $ 7.43 | $ 0.40 | $ 0.40 | $ 0.47 | $ 0.86 |
Options | Minimum | |||||
Weighted average assumptions | |||||
Expected life | 5 years 6 months | 5 years 9 months | 6 years 2 months 12 days | ||
Expected volatility | 37.50% | 39.90% | 40.60% | ||
Risk-free interest rate | 2.38% | 1.88% | 1.88% | 1.27% | 1.65% |
Options | Maximum | |||||
Weighted average assumptions | |||||
Expected life | 6 years 3 months | 6 years 3 months | 6 years 2 months 12 days | 6 years 2 months 12 days | |
Expected volatility | 49.80% | 41.50% | 39.10% | 38.60% | |
Risk-free interest rate | 3.01% | 2.32% | 2.32% | 2.25% | 2.14% |
Related-Party Transactions (D_2
Related-Party Transactions (Details) $ in Thousands | 4 Months Ended | 9 Months Ended | 12 Months Ended | |||||
May 07, 2018member | Sep. 30, 2018USD ($)member | Sep. 30, 2017USD ($) | Dec. 31, 2017USD ($)personitem | Dec. 31, 2016USD ($) | Dec. 31, 2015USD ($) | May 31, 2016item | May 31, 2016member | |
Development Agreement | ||||||||
Inventory purchases | $ 305 | $ 829 | ||||||
Medtronic | ||||||||
Board of Directors' Appointment | ||||||||
Number of person allowed for member of entities Board of Directors | 1 | 1 | ||||||
Number of voting member before the Series F preferred stock purchase agreement | 1 | 1 | ||||||
Number of voting member before the Series F preferred stock purchase agreement | 2 | 2 | ||||||
Supply Agreement | ||||||||
Number of buy right of inventory upon termination of supply agreement | 1 | 1 | ||||||
Development Agreement | ||||||||
Inventory purchases | $ 1,120 | $ 848 | $ 834 | |||||
Right-of-First-Offer of the Company | ||||||||
Period to negotiate exclusively with Medtronic on possible sale of business prior to negotiating with third party | 90 days | 90 days |
Income Taxes (Details)
Income Taxes (Details) - USD ($) | 9 Months Ended | 12 Months Ended | ||
Sep. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Operating Loss Carryforwards [Line Items] | ||||
Unrecognized tax benefits | $ 0 | $ 0 | ||
Federal tax at statutory rate | 21.00% | 35.00% | 35.00% | 35.00% |
Federal | ||||
Operating Loss Carryforwards [Line Items] | ||||
Net operating loss carryforwards | $ 110,900,000 | |||
State | ||||
Operating Loss Carryforwards [Line Items] | ||||
Net operating loss carryforwards | 65,900,000 | |||
R&D credit | ||||
Operating Loss Carryforwards [Line Items] | ||||
Credit carryforwards | $ 1,400,000 |
Segment Reporting and Signifi_6
Segment Reporting and Significant Customers (Details) $ in Thousands | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018USD ($)segment | Sep. 30, 2017USD ($) | Dec. 31, 2017USD ($)segment | Dec. 31, 2016USD ($) | Dec. 31, 2015USD ($) | |
Segment Reporting [Abstract] | |||||
Number of reporting segments | segment | 1 | 1 | |||
Segment Reporting and Significant Customers | |||||
Total revenue | $ 34,034 | $ 18,610 | $ 28,567 | $ 16,427 | $ 8,012 |
United States | |||||
Segment Reporting and Significant Customers | |||||
Total revenue | 29,580 | 15,922 | 24,293 | 13,789 | 6,132 |
Europe | |||||
Segment Reporting and Significant Customers | |||||
Total revenue | $ 4,454 | $ 2,688 | $ 4,274 | $ 2,638 | $ 1,880 |
Loss Per Share (Details)_2
Loss Per Share (Details) - shares | 9 Months Ended | 12 Months Ended | |||
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Loss Per Share | |||||
Antidilutive securities excluded from computation of diluted weighted average shares outstanding (in shares) | 2,279,014 | 14,252,134 | 14,607,106 | 11,259,726 | 9,904,353 |
Convertible preferred stock outstanding (in shares) | |||||
Loss Per Share | |||||
Antidilutive securities excluded from computation of diluted weighted average shares outstanding (in shares) | 0 | 12,111,706 | 12,111,706 | 9,367,628 | 7,995,592 |
Convertible preferred stock warrants (in shares) | |||||
Loss Per Share | |||||
Antidilutive securities excluded from computation of diluted weighted average shares outstanding (in shares) | 0 | 65,434 | 423,784 | 394,587 | 367,598 |
Convertible common stock warrants (in shares) | |||||
Loss Per Share | |||||
Antidilutive securities excluded from computation of diluted weighted average shares outstanding (in shares) | 80,884 | 0 | |||
Common stock options outstanding (in shares) | |||||
Loss Per Share | |||||
Antidilutive securities excluded from computation of diluted weighted average shares outstanding (in shares) | 2,198,130 | 2,074,994 | 2,071,616 | 1,497,511 | 1,541,163 |