EverQuote (EVER) 10-Q 14 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	EVER
Entity Registrant Name	EverQuote, Inc.
Entity Central Index Key	1,640,428
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	false
Class A Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		4,958,739
Class B Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		20,067,854

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 38,709	$ 2,363
Accounts receivable	21,789	14,694
Prepaid expenses and other current assets	1,645	593
Total current assets	62,143	17,650
Property and equipment, net	4,021	2,129
Other assets	721	740
Total assets	66,885	20,519
Current liabilities:
Accounts payable	14,615	11,894
Accrued expenses and other current liabilities	3,166	1,775
Deferred revenue	1,069	986
Current portion of long-term debt, net of discount		361
Total current liabilities	18,850	15,016
Deferred rent, net of current portion	1,179	860
Long-term debt, net of current portion		4,250
Total liabilities	20,029	20,126
Commitments and contingencies (Note 9)
Redeemable convertible preferred stock (Series A, B and B-1), $0.001 par value; no shares and 1,867,886 shares authorized at September 30, 2018 and December 31, 2017, respectively; no shares and 1,574,508 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively; aggregate liquidation preference of $36,844 at December 31, 2017		50,937
Stockholders' equity (deficit):
Preferred stock, $0.001 par value; 10,000,000 shares and no shares authorized at September 30, 2018 and December 31, 2017, respectively; no shares issued and outstanding
Additional paid-in capital	139,798	766
Accumulated deficit	(92,967)	(51,319)
Total stockholders' equity (deficit)	46,856	(50,544)
Total liabilities, redeemable convertible preferred stock and stockholders' equity (deficit)	66,885	20,519
Class A Common Stock [Member]
Stockholders' equity (deficit):
Common stock	5
Class B Common Stock [Member]
Stockholders' equity (deficit):
Common stock	$ 20	$ 9

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, authorized	0	1,867,886
Preferred stock, issued	0	1,574,508
Preferred stock, outstanding	0	1,574,508
Preferred stock, liquidation preference	$ 0	$ 36,844
Preferred Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Preferred stock, authorized	10,000,000	0
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Class A Common Stock [Member]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	220,000,000	30,004,760
Common stock, shares issued	4,949,075	24,000
Common stock, shares outstanding	4,949,075	24,000
Class B Common Stock [Member]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	30,000,000	27,566,096
Common stock, shares issued	20,071,718	8,670,992
Common stock, shares outstanding	20,071,718	8,670,992

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 41,748	$ 32,096	$ 123,570	$ 93,865
Cost and operating expenses:
Cost of revenue	3,115	1,889	8,603	5,509
Sales and marketing	35,150	27,604	105,105	82,385
Research and development	4,123	2,441	9,918	6,672
General and administrative	3,296	1,181	6,742	3,449
Total cost and operating expenses	45,684	33,115	130,368	98,015
Loss from operations	(3,936)	(1,019)	(6,798)	(4,150)
Other income (expense):
Interest expense	(3)	(116)	(199)	(268)
Interest income	131		131
Total other income (expense), net	128	(116)	(68)	(268)
Loss before income taxes	(3,808)	(1,135)	(6,866)	(4,418)
Net loss and comprehensive loss	(3,808)	(1,135)	(6,866)	(4,418)
Accretion of redeemable convertible preferred stock to redemption value		531	(37,415)	(12,248)
Net loss attributable to common stockholders	$ (3,808)	$ (604)	$ (44,281)	$ (16,666)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.15)	$ (0.07)	$ (3.12)	$ (1.89)
Weighted average common shares outstanding, basic and diluted	24,595,102	8,622,072	14,187,261	8,800,461

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net loss	$ (6,866)	$ (4,418)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	954	1,049
Stock-based compensation expense	3,876	1,372
Noncash interest expense	14	15
Deferred rent	319	388
Changes in operating assets and liabilities:
Accounts receivable	(7,095)	(3,968)
Prepaid expenses and other current assets	(1,052)	9
Other assets		(61)
Accounts payable	2,394	651
Accrued expenses and other current liabilities	1,367	475
Deferred revenue	83	17
Net cash used in operating activities	(6,006)	(4,471)
Cash flows from investing activities:
Acquisition of property and equipment, including costs capitalized for development of internal-use software	(2,476)	(999)
Net cash used in investing activities	(2,476)	(999)
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriting discounts and commissions	52,313
Proceeds from exercise of stock options	853	1,549
Repurchase of common stock		(9,229)
Proceeds from borrowings on line of credit	22,729	16,300
Repayments of borrowings on line of credit	(24,729)	(12,300)
Repayments of term loan	(2,625)	(1,125)
Payments of initial public offering costs	(3,713)
Net cash provided by (used in) financing activities	44,828	(4,805)
Net increase (decrease) in cash and cash equivalents	36,346	(10,275)
Cash and cash equivalents at beginning of period	2,363	12,400
Cash and cash equivalents at end of period	38,709	2,125
Supplemental disclosure of noncash investing and financing information:
Purchases of property and equipment included in accounts payable	351
Conversion of convertible preferred stock to common stock	88,352	98
Retirement of treasury stock		9,229
Accretion of redeemable convertible preferred stock to redemption value	$ 37,415	$ 12,248

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements Abstract
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation EverQuote, Inc. (the “Company”) was incorporated in the state of Delaware in 2008. Through its internet websites, the Company operates an online marketplace for consumers shopping for auto, home and life insurance quotes. The Company generates revenue by selling consumer referrals to insurance provider customers, consisting of carriers and agents, and indirect distributors in the United States. The Company is subject to a number of risks and uncertainties common to companies in similar industries and stages of development including, but not limited to, rapid technological changes, competition from substitute products and services from larger companies, protection of proprietary technology, customer concentration, patent litigation, the need to obtain additional financing to support growth and dependence on third parties and key individuals. On July 2, 2018, the Company completed an initial public offering (“IPO”), in which it issued and sold 3,125,000 shares of Class A common stock at a public offering price of $18.00 per share, resulting in net proceeds to the Company of approximately $48.6 million after deducting underwriting discounts and commissions and other offering costs. Additionally, certain of the Company’s stockholders sold 1,562,500 shares of Class A common stock at the same public offering price of $18.00 per share. The Company did not receive any proceeds from the sale of shares by its stockholders. Upon closing of the IPO, the Company’s outstanding redeemable convertible preferred stock automatically converted into shares of Class B common stock (see Note 5). The accompanying condensed financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Since inception, the Company has incurred operating losses, including net losses of $6.9 million for the nine months ended September 30, 2018 and $5.1 million for the year ended December 31, 2017. As of September 30, 2018, the Company had an accumulated deficit of $93.0 million. The Company has primarily funded its operations through issuances of shares of redeemable convertible preferred stock and common stock, debt, including a revolving line of credit with Western Alliance Bank, cash flows from operations and proceeds from the Company’s IPO. As of November 14, 2018, the issuance date of the interim financial statements, the Company expects that its cash and cash equivalents will be sufficient to fund its operating expenses and capital expenditure requirements for at least the next 12 months from the issuance date of the interim financial statements, without considering available borrowings under the Company’s revolving line of credit. The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The Company is an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”), and may remain an emerging growth company until the last day of the fiscal year following the fifth anniversary of the IPO, subject to specified conditions. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected not to “opt out” of such extended transition period, which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company will adopt the new or revised standard at the time private companies adopt the new or revised standard, provided that the Company continues to be an emerging growth company.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Unaudited Interim Financial Information The balance sheet at December 31, 2017 was derived from audited financial statements but does not include all disclosures required by GAAP. The accompanying unaudited financial statements as of September 30, 2018 and for the three and nine months ended September 30, 2018 and 2017 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto for the year ended December 31, 2017 included in the Company’s Registration Statement on Form S-1, File No. 333-225379 on Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, revenue recognition, the expensing and capitalization of website and software development costs, the valuation of common and preferred stock prior to the IPO, the valuation of stock-based awards and income taxes. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Changes in estimates are recorded in periods in which they become known. Actual results may differ from those estimates or assumptions. Concentrations of Credit Risk and of Significant Customers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents at two accredited financial institutions. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company sells its consumer referrals to insurance provider customers, consisting of carriers and agents, and indirect distributors in the United States. For the three months ended September 30, 2018 and 2017, one customer represented 22% and 19%, respectively, of total revenue. For the nine months ended September 30, 2018 and 2017, one customer represented 20% and 21%, respectively, of total revenue. As of September 30, 2018, two customers accounted for 28% and 13% of the accounts receivable balance. As of December 31, 2017, four customers accounted for 12%, 11%, 11% and 11% of the accounts receivable balance. Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents of $22.5 million as of September 30, 2018, consisting of money market funds, are carried at fair value based on Level 1 inputs. The carrying values of the Company’s accounts receivable, accounts payable and accrued expenses and other current liabilities approximate their fair values due to the short-term nature of these assets and liabilities. Revenue Recognition The Company derives its revenue by selling consumer referrals to its insurance provider customers, including insurance carriers and agents. The Company recognizes revenue in accordance with Accounting Standards Codification (“ASC”) Topic 605, Revenue Recognition Amounts received prior to satisfying the revenue recognition criteria listed above are recorded as deferred revenue in the accompanying balance sheets. Amounts expected to be recognized as revenue within 12 months of the balance sheet date are classified as current deferred revenue. Advertising Expense Advertising expense consists of variable costs that are related to attracting consumers to the Company’s marketplace, increasing downloads of its social safe-driving mobile app, EverDrive, and promoting its marketplace to insurance carriers and agents. The Company expenses advertising costs as incurred and such costs are included in sales and marketing expense in the accompanying statements of operations and comprehensive loss. For the three months ended September 30, 2018 and 2017, advertising expense totaled $29.2 million and $23.0 million, respectively. For the nine months ended September 30, 2018 and 2017, advertising expense totaled $87.7 million and $67.6 million, respectively. Accounts Receivable The Company provides credit to customers in the ordinary course of business and believes its credit policies are prudent and reflect industry practices and business risk. Management reviews accounts receivable on a periodic basis and reserves for receivables in the Company’s allowance for doubtful accounts on a specific identification basis when they are determined to be uncollectible. After the Company has exhausted all collection efforts, the outstanding receivable is written off against the allowance. The Company had no allowance for doubtful accounts as of September 30, 2018 and December 31, 2017, as amounts were deemed to be collectible. Recently Adopted Accounting Pronouncements In May 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting 2017-09”), 2017-09 2017-09 Recently Issued Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) 2014-09”), catch-up non-public non-public ASU 2014-09 will In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) 2016-02”), right-of-use non-public 2016-02 No. 2018-11, Leases (Topic 842) catch-up ASU 2016-02 2016-02 In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments (Topic 230) 2016-15”), non-public 2016-15 non-public In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230) 2016-18”), beginning-of-period end-of-period 2016-18 non-public 2016-18 non-public In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception 2017-11”). 2017-11 non-public 2017-11 In June 2018, the FASB issued ASU No. 2018-07, Compensation – Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting 2018-07”). 2018-07 non-employees 2018-07 non-public 2018-07 2014-09. ASU 2018-07 2018-07

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	3. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, 2018 December 31, 2017 Accrued advertising expenses $ 588 $ 721 Accrued employee compensation and benefits 1,822 433 Accrued professional fees 331 154 Other current liabilities 425 467 $ 3,166 $ 1,775

Loan and Security Agreement

Loan and Security Agreement	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Loan and Security Agreement	4. Loan and Security Agreement As of December 31, 2017, the Company had outstanding borrowings under an amended Loan and Security Agreement including borrowings under a revolving line of credit and a term loan. The interest rate for the revolving line of credit was 5.0% as of December 31, 2017. The term loan was repayable in 36 equal monthly installments through August 2019 and accrued interest at an annual rate of 2.0% above the greater of 3.5% or the prime rate. The interest rate for the term loan was 6.5% as of December 31, 2017. Borrowings under the amended Loan and Security Agreement were collateralized by substantially all of the Company’s assets and property. In March 2018, the Company executed the 2018 Loan Modification (the “2018 Loan Modification”) to modify the amended Loan and Security Agreement to increase the revolving line of credit from $6.0 million to $11.0 million, extend the maturity date of the revolving line of credit to March 2020 and eliminate the term loan. Pursuant to the 2018 Loan Modification, borrowings under the revolving line of credit cannot exceed 80% of eligible accounts receivable balances and continue to bear interest at one-half Under the 2018 Loan Modification, the Company is subject to specified affirmative and negative covenants until maturity. These covenants include limitations on the Company’s ability to incur additional indebtedness and engage in certain fundamental business transactions, such as mergers or acquisitions. In addition, pursuant to the 2018 Loan Modification, the Company is required to maintain a financial performance covenant: a minimum asset coverage ratio of 1.5 to 1, calculated as the sum of unrestricted cash and qualified accounts receivable divided by borrowings outstanding under the revolving line of credit. Events which would meet the criteria of a default under the 2018 Loan Modification include failure to make payments when due, insolvency events, failure to comply with covenants or material adverse events with respect to the Company. As of September 30, 2018, the Company was in compliance with all covenants related to the revolving line of credit. There can be no guarantee that these covenants will be met in the future, and if not met, that waivers will be obtained. As of September 30, 2018, the Company had no amounts outstanding on the revolving line of credit. As of September 30, 2018, $11.0 million was available for borrowing under the revolving line of credit.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	9 Months Ended
	Sep. 30, 2018
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock	5. Redeemable Convertible Preferred Stock The Company issued Series A redeemable convertible preferred stock (the “Series A Preferred Stock”), Series B redeemable convertible preferred stock (the “Series B Preferred Stock”) and Series B-1 B-1 B-1 In February 2017, holders of 97,943 shares of Series A Preferred Stock converted their shares to 783,544 shares of common stock. No additional consideration was paid or received by the Company in connection with these conversions. In April 2017, the Company exchanged 132,749 shares of Series B Preferred Stock for an equal number of shares of Series B-1 B-1 B-1 As of December 31, 2017, the Preferred Stock consisted of the following (in thousands, except share amounts): Preferred Stock Preferred Stock Carrying Value Liquidation Common Stock Series A Preferred Stock 1,265,100 971,722 $ 972 $ 972 7,773,776 Series B Preferred Stock 470,037 470,037 38,961 27,972 3,760,296 Series B-1 132,749 132,749 11,004 7,900 1,061,992 1,867,886 1,574,508 $ 50,937 $ 36,844 12,596,064 In the three months ended September 30, 2018 and 2017, the Company recorded adjustments of $0 and $(0.5) million, respectively, to the carrying value of Series B and B-1 paid-in B-1 paid-in Upon the closing of the Company’s IPO in July 2018, all 1,574,508 shares of the Company’s then-outstanding Preferred Stock automatically converted into an aggregate of 12,596,064 shares of the Company’s Class B common stock. Upon conversion of the redeemable convertible preferred stock, the Company reclassified the carrying value of the Preferred Stock to common stock and additional paid-in

Equity

Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Equity	6. Equity On June 15, 2018, the Company effected an eight-for-one Upon closing of the IPO on July 2, 2018, the Company’s authorized shares of common stock were increased to 220,000,000 shares of Class A common stock and 30,000,000 shares of Class B common stock. The Company also authorized 10,000,000 shares of undesignated preferred stock. Each share of Class A common stock entitles the holder to one vote for each share on all matters submitted to a vote of the Company’s stockholders at all meetings of stockholders and written actions in lieu of meetings. Each share of Class B common stock entitles the holder to ten votes for each share on all matters submitted to a vote of the Company’s stockholders at all meetings of stockholders and written actions in lieu of meetings. Holders of both classes of common stock are entitled to receive dividends, when and if declared by the board of directors. Each share of Class B common stock is convertible into one share of Class A common stock at the option of the holder at any time. Automatic conversion shall occur upon the occurrence of a transfer of such share of Class B common stock or at the date and time, or the occurrence of an event, specified by a vote or written consent of the holders of a majority of the voting power of the then outstanding shares of Class B common stock. A transfer is described as a sale, assignment, transfer, conveyance, hypothecation or disposition of such share or any legal or beneficial interest in such share other than certain permitted transfers as described in the Restated Certificate of Incorporation, including a transfer to a holder of Preferred Stock. Each share of Class B common stock held by a stockholder shall automatically convert into one fully paid and non-assessable In the nine months ended September 30, 2018, 1,735,300 shares of Class B common stock were automatically converted to 1,735,300 shares of Class A common stock pursuant to transfers as described above. No additional consideration was paid or received by the Company in connection with these exchanges. In the nine months ended September 30, 2017, the Company repurchased 1,341,216 shares of its common stock at a price of $6.89 per share for a total cost of $9.2 million. The repurchase was pursuant to a tender offer made by the Company to its stockholders, including employee stockholders. The price paid by the Company at the settlement date of each tender was the estimated fair value of the Company’s common stock at such settlement date. The Company immediately retired all outstanding treasury shares after the repurchase of common stock. Acquisitions of treasury stock have been recorded at cost. Treasury stock held was reported as a deduction from stockholders’ deficit. When the treasury stock was retired, the carrying value of the treasury stock was allocated between additional paid-in paid-in paid-in paid-in

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	7. Stock-Based Compensation 2008 Stock Incentive Plan The Company’s 2008 Stock Incentive Plan, as amended (the “2008 Plan”), provided for the Company to issue equity awards to employees, consultants, advisors and directors. Under the 2008 Plan, the Company could grant stock-based incentive awards, including incentive or nonqualified stock options and restricted stock units, as determined by the board of directors. The total number of shares of common stock that could have been issued under the 2008 Plan was 8,440,712 shares. Upon effectiveness of the Company’s 2018 Equity Incentive Plan, (the “2018 Plan” and, together with the 2008 Plan, the “Plans”) on June 27, 2018, the remaining 583,056 shares that were available for grant under the 2008 Plan became available for grant under the 2018 Plan and no future grants will be made under the 2008 Plan. Additionally, shares underlying awards under the 2008 Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right (subject, in the case of incentive stock options, to any limitations of the Internal Revenue Code) will be available for future grants under the 2018 Plan. Shares of common stock issued upon exercise of stock options granted prior to September 8, 2017 will be issued as Class B common stock. Shares of common stock issued upon exercise of stock options granted after September 8, 2017 will be issued as Class A common stock. 2018 Equity Incentive Plan On June 14, 2018, the Company’s board of directors adopted and its stockholders approved the 2018 Plan, which became effective on June 27, 2018. The 2018 Plan provides for the grant of incentive stock options, non-qualified Options and restricted stock granted under the Plans vest over periods determined by the board of directors. Options granted under the Plans expire ten years from the date of the grant. The exercise price for stock options granted is not less than the fair value of common shares as determined by the board of directors as of the date of grant. Prior to the Company’s IPO, the Company’s board of directors valued the Company’s common stock, taking into consideration its most recently available valuation of common stock performed by third parties as well as additional factors which may have changed since the date of the most recent contemporaneous valuation through the date of grant. Award Issuances During the nine months ended September 30, 2018, the Company granted options to employees and directors for the purchase of 1,342,840 shares of Class A common stock with a weighted average exercise price of $10.40 per share and a weighted average grant-date fair value of $5.09 per share. During the nine months ended September 30, 2018, the Company granted service- and performance-based RSUs to employees and directors for the right to receive 2,103,272 shares of Class A common stock with a weighted average grant date fair value of $17.27 per share. Stock-Based Compensation The Company recorded stock-based compensation expense in the following expense categories of its statements of operations and comprehensive loss (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Cost of revenue $ 12 $ 7 $ 29 $ 20 Sales and marketing 607 166 1,277 577 Research and development 858 127 1,150 346 General and administrative 1,109 133 1,420 429 $ 2,586 $ 433 $ 3,876 $ 1,372 As of September 30, 2018, unrecognized compensation expense related to unvested options was $8.5 million, which is expected to be recognized over a weighted average period of 3.4 years.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes 2017 U.S. Tax Reform On December 22, 2017, tax reform legislation commonly known as the Tax Cuts and Jobs Act (the “TCJA”) was signed into United States law. The TCJA includes a number of changes to existing tax law, including, among other things, a permanent reduction in the federal corporate income tax rate from 35% to 21%, effective as of January 1, 2018, as well as a limitation of the deduction for net operating losses to 80% of current year taxable income and the elimination of net operating loss carrybacks, in each case, for losses arising in taxable years beginning after December 31, 2017 (though any such net operating losses may be carried forward indefinitely). The federal tax rate change resulted in a reduction of the Company’s deferred tax assets and liabilities, and a corresponding reduction to its valuation allowance. As a result, no income tax expense or benefit was recognized as of the enactment date of the TCJA. The other provisions of the TCJA did not have a material impact on the Company’s financial statements. Income Taxes The Company had no income tax expense for the three or nine months ended September 30, 2018 and 2017. The Company has no foreign operations and therefore, has not provided for any foreign taxes.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Operating Leases The Company leases office space in Cambridge, Massachusetts under a non-cancelable non-cancelable Lease incentives, payment escalations and rent holidays specified in the lease agreements are accrued or deferred as appropriate such that rent expense per square foot is recognized on a straight-line basis over the terms of occupancy. As of September 30, 2018 and December 31, 2017, the Company had a deferred rent liability of $1.2 million and $0.9 million, respectively. As of September 30, 2018 and December 31, 2017, the Company maintained security deposits of $0.4 million with the landlords of its leases, which amounts are included in other assets (long-term) on the Company’s balance sheets. Future minimum lease payments under the operating leases as of September 30, 2018 are as follows (in thousands): Year Ending December 31, 2018 (three months ending December 31) $ 457 2019 2,243 2020 2,573 2021 2,659 2022 2,502 Thereafter 4,456 $ 14,890 For the three months ended September 30, 2018 and 2017, the Company recognized rent expense of $0.5 million and $0.5 million, respectively. For the nine months ended September 30, 2018 and 2017, the Company recognized rent expense of $1.6 million and $1.2 million, respectively. Indemnification Agreements In the normal course of business, the Company may provide indemnification of varying scope and terms to third parties and enters into commitments and guarantees (“Agreements”) under which it may be required to make payments. The duration of these Agreements varies, and in certain cases, is indefinite. Furthermore, many of these Agreements do not limit the Company’s maximum potential payment exposure. In addition, the Company has entered into indemnification agreements with members of its board of directors and executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. Through December 31, 2017 and September 30, 2018, the Company has not incurred any material costs as a result of such indemnifications. The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and it has not accrued any liabilities related to such obligations in its financial statements as of September 30, 2018 or December 31, 2017. Legal Proceedings The Company, from time to time, is subject to legal proceedings and claims that arise in the normal course of its business. In the opinion of management, the amount of ultimate liability with respect to any such actions should not have a material adverse effect on the Company’s results of operations of financial position. As of September 30, 2018 and December 31, 2017, the Company does not have any contingency reserves established for any litigation liabilities.

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Net Loss per Share	10. Net Loss per Share The Company has two classes of common stock. The rights of the holders of Class A and Class B common stock are identical, except with respect to voting and conversion. As a result, basic and diluted net loss per share of Class A common stock and share of Class B common stock are equivalent. Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Numerator: Net loss $ (3,808 ) $ (1,135 ) $ (6,866 ) $ (4,418 ) Accretion of redeemable convertible preferred stock to redemption value — 531 (37,415 ) (12,248 ) Net loss attributable to common stockholders $ (3,808 ) $ (604 ) $ (44,281 ) $ (16,666 ) Denominator: Weighted average common shares outstanding, basic and diluted 24,595,102 8,622,072 14,187,261 8,800,461 Net loss per share attributable to common stockholders, basic and diluted $ (0.15 ) $ (0.07 ) $ (3.12 ) $ (1.89 ) The Company’s potentially dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share attributable to common stockholders. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the three and nine months ended September 30, 2018 and 2017 because including them would have had an anti-dilutive effect: September 30, 2018 2017 Redeemable convertible preferred stock (as converted to common stock) — 12,596,064 Options to purchase common stock 3,908,922 3,452,920 Unvested restricted stock units 2,280,993 264,000 6,189,915 16,312,984

Retirement Plan

Retirement Plan	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Retirement Plan	11. Retirement Plan The Company has established a defined-contribution plan under Section 401(k) of the Internal Revenue Code (the “401(k) Plan”). The 401(k) Plan covers all employees who meet defined minimum age and service requirements, and allows participants to defer a portion of their annual compensation on a pre-tax

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	12. Related Party Transactions The Company has, in the ordinary course of business, entered into arrangements with other companies who have shareholders in common with the Company. Pursuant to these arrangements, related-party affiliates receive payments for providing website visitor referrals. During each of the three months ended September 30, 2018 and 2017, the Company recorded sales and marketing expenses of $2.2 million related to these arrangements. During the nine months ended September 30, 2018 and 2017, the Company recorded sales and marketing expenses of $6.6 million and $6.3 million, respectively, related to these arrangements. During each of the three months ended September 30, 2018 and 2017, the Company paid $2.0 million related to these arrangements. During the nine months ended September 30, 2018 and 2017, the Company paid $7.0 million and $6.4 million, respectively, related to these arrangements. As of September 30, 2018 and December 31, 2017, amounts due to related-party affiliates totaled $1.2 million and $1.6 million, respectively, which amounts were included in accounts payable on the balance sheets.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Unaudited Interim Financial Information	Unaudited Interim Financial Information The balance sheet at December 31, 2017 was derived from audited financial statements but does not include all disclosures required by GAAP. The accompanying unaudited financial statements as of September 30, 2018 and for the three and nine months ended September 30, 2018 and 2017 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto for the year ended December 31, 2017 included in the Company’s Registration Statement on Form S-1, File No. 333-225379 on
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, revenue recognition, the expensing and capitalization of website and software development costs, the valuation of common and preferred stock prior to the IPO, the valuation of stock-based awards and income taxes. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Changes in estimates are recorded in periods in which they become known. Actual results may differ from those estimates or assumptions.
Concentrations of Credit Risk and of Significant Customers	Concentrations of Credit Risk and of Significant Customers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. The Company maintains its cash and cash equivalents at two accredited financial institutions. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company sells its consumer referrals to insurance provider customers, consisting of carriers and agents, and indirect distributors in the United States. For the three months ended September 30, 2018 and 2017, one customer represented 22% and 19%, respectively, of total revenue. For the nine months ended September 30, 2018 and 2017, one customer represented 20% and 21%, respectively, of total revenue. As of September 30, 2018, two customers accounted for 28% and 13% of the accounts receivable balance. As of December 31, 2017, four customers accounted for 12%, 11%, 11% and 11% of the accounts receivable balance.
Revenue Recognition	Revenue Recognition The Company derives its revenue by selling consumer referrals to its insurance provider customers, including insurance carriers and agents. The Company recognizes revenue in accordance with Accounting Standards Codification (“ASC”) Topic 605, Revenue Recognition Amounts received prior to satisfying the revenue recognition criteria listed above are recorded as deferred revenue in the accompanying balance sheets. Amounts expected to be recognized as revenue within 12 months of the balance sheet date are classified as current deferred revenue.
Advertising Expense	Advertising Expense Advertising expense consists of variable costs that are related to attracting consumers to the Company’s marketplace, increasing downloads of its social safe-driving mobile app, EverDrive, and promoting its marketplace to insurance carriers and agents. The Company expenses advertising costs as incurred and such costs are included in sales and marketing expense in the accompanying statements of operations and comprehensive loss. For the three months ended September 30, 2018 and 2017, advertising expense totaled $29.2 million and $23.0 million, respectively. For the nine months ended September 30, 2018 and 2017, advertising expense totaled $87.7 million and $67.6 million, respectively.
Accounts Receivable	Accounts Receivable The Company provides credit to customers in the ordinary course of business and believes its credit policies are prudent and reflect industry practices and business risk. Management reviews accounts receivable on a periodic basis and reserves for receivables in the Company’s allowance for doubtful accounts on a specific identification basis when they are determined to be uncollectible. After the Company has exhausted all collection efforts, the outstanding receivable is written off against the allowance. The Company had no allowance for doubtful accounts as of September 30, 2018 and December 31, 2017, as amounts were deemed to be collectible.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In May 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting 2017-09”), 2017-09 2017-09 Recently Issued Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) 2014-09”), catch-up non-public non-public ASU 2014-09 will In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) 2016-02”), right-of-use non-public 2016-02 No. 2018-11, Leases (Topic 842) catch-up ASU 2016-02 2016-02 In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments (Topic 230) 2016-15”), non-public 2016-15 non-public In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230) 2016-18”), beginning-of-period end-of-period 2016-18 non-public 2016-18 non-public In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception 2017-11”). 2017-11 non-public 2017-11 In June 2018, the FASB issued ASU No. 2018-07, Compensation – Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting 2018-07”). 2018-07 non-employees 2018-07 non-public 2018-07 2014-09. ASU 2018-07 2018-07
Fair Value Measurements	Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The Company’s cash equivalents of $22.5 million as of September 30, 2018, consisting of money market funds, are carried at fair value based on Level 1 inputs. The carrying values of the Company’s accounts receivable, accounts payable and accrued expenses and other current liabilities approximate their fair values due to the short-term nature of these assets and liabilities.

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, 2018 December 31, 2017 Accrued advertising expenses $ 588 $ 721 Accrued employee compensation and benefits 1,822 433 Accrued professional fees 331 154 Other current liabilities 425 467 $ 3,166 $ 1,775

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock (Tables)	9 Months Ended
	Sep. 30, 2018
Temporary Equity Disclosure [Abstract]
Summary of Preferred Stock	As of December 31, 2017, the Preferred Stock consisted of the following (in thousands, except share amounts): Preferred Stock Preferred Stock Carrying Value Liquidation Common Stock Series A Preferred Stock 1,265,100 971,722 $ 972 $ 972 7,773,776 Series B Preferred Stock 470,037 470,037 38,961 27,972 3,760,296 Series B-1 132,749 132,749 11,004 7,900 1,061,992 1,867,886 1,574,508 $ 50,937 $ 36,844 12,596,064

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock-Based Compensation Expense of Statements of Operations and Comprehensive Loss	The Company recorded stock-based compensation expense in the following expense categories of its statements of operations and comprehensive loss (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Cost of revenue $ 12 $ 7 $ 29 $ 20 Sales and marketing 607 166 1,277 577 Research and development 858 127 1,150 346 General and administrative 1,109 133 1,420 429 $ 2,586 $ 433 $ 3,876 $ 1,372

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Summary of Future Minimum Lease Payments under the Operating Leases	Future minimum lease payments under the operating leases as of September 30, 2018 are as follows (in thousands): Year Ending December 31, 2018 (three months ending December 31) $ 457 2019 2,243 2020 2,573 2021 2,659 2022 2,502 Thereafter 4,456 $ 14,890

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Summary of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Numerator: Net loss $ (3,808 ) $ (1,135 ) $ (6,866 ) $ (4,418 ) Accretion of redeemable convertible preferred stock to redemption value — 531 (37,415 ) (12,248 ) Net loss attributable to common stockholders $ (3,808 ) $ (604 ) $ (44,281 ) $ (16,666 ) Denominator: Weighted average common shares outstanding, basic and diluted 24,595,102 8,622,072 14,187,261 8,800,461 Net loss per share attributable to common stockholders, basic and diluted $ (0.15 ) $ (0.07 ) $ (3.12 ) $ (1.89 )
Summary of Diluted Net Loss Per Share Attributable to Common Stockholders	The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the three and nine months ended September 30, 2018 and 2017 because including them would have had an anti-dilutive effect: September 30, 2018 2017 Redeemable convertible preferred stock (as converted to common stock) — 12,596,064 Options to purchase common stock 3,908,922 3,452,920 Unvested restricted stock units 2,280,993 264,000 6,189,915 16,312,984

Nature of the Business and Ba_2

Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jul. 02, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Subsidiary, Sale of Stock [Line Items]
Operating loss		$ (3,808)	$ (1,135)	$ (6,866)	$ (4,418)	$ (5,100)
Accumulated deficit		$ (92,967)		$ (92,967)		$ (51,319)
Initial Public Offering (IPO) [Member] | Class A Common Stock [Member]
Subsidiary, Sale of Stock [Line Items]
Shares of common stock issued and sold	3,125,000
Public offering price, per share	$ 18
Net proceeds from initial public offering	$ 48,600
Sale of stock sold by stockholders shares	1,562,500
Public offering price, per share	$ 18

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018USD ($)Customers	Sep. 30, 2017USD ($)Customers	Sep. 30, 2018USD ($)Customers	Sep. 30, 2017USD ($)Customers	Dec. 31, 2017USD ($)Customers	Nov. 30, 2016USD ($)
Significant Accounting Policies [Line Items]
Advertising expenses	$ 29,200,000	$ 23,000,000	$ 87,700,000	$ 67,600,000
Allowance for doubtful accounts	0		0		$ 0
Security deposit	400,000		400,000		$ 400,000
Fair Value, Inputs, Level 1 [Member]
Significant Accounting Policies [Line Items]
Cash equivalents	$ 22,500,000		$ 22,500,000
Accounting Standards Update 2016-18 [Member]
Significant Accounting Policies [Line Items]
Security deposit						$ 300,000
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Number of major customers | Customers	1	1	1	1
Concentration risk percentage	22.00%	19.00%	20.00%	21.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Number of major customers | Customers			2		4
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Customers A [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage			28.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Customers B [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage			13.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Customers C [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage					12.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Customers D [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage					11.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Customers E [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage					11.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Customers F [Member]
Significant Accounting Policies [Line Items]
Concentration risk percentage					11.00%

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued advertising expenses	$ 588	$ 721
Accrued employee compensation and benefits	1,822	433
Accrued professional fees	331	154
Other current liabilities	425	467
Accrued expenses and other current liabilities	$ 3,166	$ 1,775

Loan and Security Agreement - A

Loan and Security Agreement - Additional Information (Detail) - Loan and Security Agreement [Member]	Mar. 27, 2018USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)Installment
Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, payment terms			The term loan was repayable in 36 equal monthly installments through August 2019
Credit facility, maturity date			Aug. 31, 2019
Number of monthly installments | Installment			36
Debt instrument, interest rate terms			Accrued interest at an annual rate of 2.0% above the greater of 3.5% or the prime rate.
Annual rate of accrued interest			2.00%
Debt instrument interest rate during period minimum stated percentage			3.50%
Interest rate			6.50%
Term Loan [Member] | 2018 Loan Modification [Member]
Debt Instrument [Line Items]
Repayment of term loan	$ 2,300,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Interest rate at end of period			5.00%
Credit facility borrowing capacity			$ 6,000,000
Revolving Credit Facility [Member] | 2018 Loan Modification [Member]
Debt Instrument [Line Items]
Credit facility, maturity date		Mar. 31, 2020
Annual rate of accrued interest		0.50%
Debt instrument interest rate during period minimum stated percentage		4.25%
Credit facility borrowing capacity		$ 11,000,000
Maximum percentage borrowings of eligible accounts receivable		80.00%
Debt instrument, interest rate description		bear interest at one-half percent (0.5%) above the greater of 4.25% or the prime rate.
Debt Instrument, Covenant Description		The Company is required to maintain a financial performance covenant a minimum asset coverage ratio of 1.5 to 1, calculated as the sum of unrestricted cash and qualified accounts receivable divided by borrowings outstanding under the revolving line of credit. Events which would meet the criteria of a default under the 2018 Loan Modification include failure to make payments when due, insolvency events, failure to comply with covenants or material adverse events with respect to the Company
Revolving line of credit outstanding amount		$ 0
Borrowing under revolving line of credit, remaining amount		$ 11,000,000

Redeemable Convertible Prefer_3

Redeemable Convertible Preferred Stock - Additional Information (Detail) - USD ($) $ in Millions	Jul. 02, 2018	Apr. 30, 2017	Feb. 28, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Series A Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of stock, shares converted			97,943
Series B Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of stock, shares converted		132,749
Series B-1 Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of stock, common stock issued		132,749
Series B and B-1 Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Adjustment to carrying value				$ 0	$ (0.5)	$ 37.4	$ 12.2
Increase (decrease) to additional paid-in capital and accumulated deficit				$ 0	$ 0.5	$ (37.4)	$ (12.2)
Class B Common Stock [Member]
Class of Stock [Line Items]
Conversion of stock, shares converted						1,735,300
Conversion of stock, common stock issued	12,596,064
Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of stock, shares converted	1,574,508
Common Stock [Member]
Class of Stock [Line Items]
Conversion of stock, common stock issued			783,544

Redeemable Convertible Prefer_4

Redeemable Convertible Preferred Stock - Summary of Preferred Stock (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Temporary Equity [Line Items]
Preferred stock authorized	0	1,867,886
Preferred stock issued	0	1,574,508
Preferred stock outstanding	0	1,574,508
Preferred share, Carrying Value		$ 50,937
Preferred share, liquidation preference	$ 0	$ 36,844
Common Stock Issuable Upon Conversion		12,596,064
Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock authorized		1,265,100
Preferred stock issued		971,722
Preferred stock outstanding		971,722
Preferred share, Carrying Value		$ 972
Preferred share, liquidation preference		$ 972
Common Stock Issuable Upon Conversion		7,773,776
Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock authorized		470,037
Preferred stock issued		470,037
Preferred stock outstanding		470,037
Preferred share, Carrying Value		$ 38,961
Preferred share, liquidation preference		$ 27,972
Common Stock Issuable Upon Conversion		3,760,296
Series B-1 Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock authorized		132,749
Preferred stock issued		132,749
Preferred stock outstanding		132,749
Preferred share, Carrying Value		$ 11,004
Preferred share, liquidation preference		$ 7,900
Common Stock Issuable Upon Conversion		1,061,992

Equity - Additional Information

Equity - Additional Information (Detail) $ / shares in Units, $ in Millions	Jul. 02, 2018shares	Jun. 15, 2018shares	Sep. 30, 2018shares	Sep. 30, 2017USD ($)$ / sharesshares	Dec. 31, 2017shares
Class of Stock [Line Items]
Preferred stock, authorized	10,000,000		10,000,000		0
Number of common stock repurchased				1,341,216
Stock price per share of common stock repurchased | $ / shares				$ 6.89
Value of common stock repurchased | $				$ 9.2
Class A Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized	220,000,000		220,000,000		30,004,760
Common stock, voting right			Class A common stock entitles the holder to one vote for each share
Conversion of stock, shares issued			1,735,300
Class B Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized	30,000,000		30,000,000		27,566,096
Common stock, voting right			Class B common stock entitles the holder to ten votes for each share
Common stock, conversion features			Each share of Class B common stock is convertible into one share of Class A common stock at the option of the holder at any time. Each share of Class B common stock held by a stockholder shall automatically convert into one fully paid and non-assessable share of Class A common stock nine months after the death or incapacity of the holder of such Class B common stock.
Conversion of stock, shares converted			1,735,300
Conversion of stock, shares issued	12,596,064
Forward Stock Split [Member]
Class of Stock [Line Items]
Forward stock split description			Eight-for-one forward stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company's Preferred Stock.
Forward stock split ratio		8
Common stock, shares authorized		57,570,856

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jun. 14, 2018	Sep. 30, 2018	Jun. 27, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options expiration period		10 years
Unrecognized compensation expense related to unvested options		$ 8.5
Compensation expense, expected recognition period		3 years 4 months 24 days
Employees And Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, shares		1,342,840
Weighted average exercise price, per share		$ 10.40
Weighted average grant date fair value, per share		$ 5.09
Employees And Directors [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, shares		2,103,272
Weighted average grant date fair value, per share		$ 17.27
2018 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, common stock available for grant		777,508
2018 Equity Incentive Plan [Member] | Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, common stock available for grant	2,149,480
2018 Equity Incentive Plan [Member] | Class A Common Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for issuance	2,500,000
2018 Equity Incentive Plan [Member] | Class A Common Stock and Class B Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, number of additional shares available from 2008 Stock Incentive Plan	583,056
2018 Equity Incentive Plan [Member] | Class A Common Stock and Class B Common Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, common stock available for grant	5,028,832
Percentage of shares of common stock available for issuance	5.00%
2008 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, common stock available for grant		8,440,712
Share-based Compensation, common stock available for grant			583,056

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-Based Compensation Expense of Statements of Operations and Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,586	$ 433	$ 3,876	$ 1,372
Cost of Revenue [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	12	7	29	20
Sales and Marketing [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	607	166	1,277	577
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	858	127	1,150	346
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,109	$ 133	$ 1,420	$ 429

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal corporate income tax rate			21.00%		35.00%
Tax Cuts and Jobs Act, change in tax rate, income tax expense (benefit)					$ 0
Net operating loss, limitation percentage			80.00%
Income tax expense	$ 0	$ 0	$ 0	$ 0
Foreign taxes			$ 0

Commitments and Contingencies -

Commitments and Contingencies -Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Operating Leased Assets [Line Items]
Operating lease commencement period			2019-03
Extended operating lease expiration period			2024-09
Deferred rent liability	$ 1.2		$ 1.2		$ 0.9
Security deposits	0.4		0.4		$ 0.4
Rent expense	$ 0.5	$ 0.5	$ 1.6	$ 1.2
Cambridge, Massachusetts [Member]
Operating Leased Assets [Line Items]
Operating lease expiration period			2024-09
Woburn Massachusetts [Member]
Operating Leased Assets [Line Items]
Operating lease expiration period			2022-01

Future Minimum Lease Payments U

Future Minimum Lease Payments Under Operating Leases (Detail) $ in Thousands	Sep. 30, 2018USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018 (three months ending December 31)	$ 457
2,019	2,243
2,020	2,573
2,021	2,659
2,022	2,502
Thereafter	4,456
Total	$ 14,890

Net Loss and Unaudited Pro Form

Net Loss and Unaudited Pro Forma Net Loss per Share - Summary of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Numerator:
Net loss	$ (3,808)	$ (1,135)	$ (6,866)	$ (4,418)	$ (5,100)
Accretion of redeemable convertible preferred stock to redemption value		531	(37,415)	(12,248)
Net loss attributable to common stockholders	$ (3,808)	$ (604)	$ (44,281)	$ (16,666)
Denominator:
Weighted average common shares outstanding, basic and diluted	24,595,102	8,622,072	14,187,261	8,800,461
Net loss per share attributable to common stockholders, basic and diluted	$ (0.15)	$ (0.07)	$ (3.12)	$ (1.89)

Net Loss and Unaudited Pro Fo_2

Net Loss and Unaudited Pro Forma Net Loss per Share - Summary of Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) - shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	6,189,915	16,312,984
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount		12,596,064
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3,908,922	3,452,920
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	2,280,993	264,000

Retirement Plan - Additional In

Retirement Plan - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Retirement Benefits [Abstract]
Contribution to defined contribution savings plan	$ 0.1	$ 0.1	$ 0.3	$ 0.1

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Related Party Transactions [Abstract]
Sales and marketing expenses from transactions with related party	$ 2.2	$ 2.2	$ 6.6	$ 6.3
Payment to related party	2	$ 2	7	$ 6.4
Due to affiliate	$ 1.2		$ 1.2		$ 1.6