Magnite (MGNI) 10-Q 6 Nov 19 2019 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-36384
Entity Registrant Name	RUBICON PROJECT, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8881738
Entity Address, Address Line One	12181 Bluff Creek Drive,
Entity Address, Address Line Two	4th Floor
Entity Address, City or Town	Los Angeles,
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90094
City Area Code	(310)
Local Phone Number	207-0272
Title of 12(b) Security	Common stock, par value $0.00001 per share
Trading Symbol	RUBI
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		53,071,171
Entity Central Index Key	0001595974
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 85,122	$ 80,452
Marketable securities	0	7,524
Accounts receivable, net	172,284	205,683
Prepaid expenses and other current assets	5,773	6,882
TOTAL CURRENT ASSETS	263,179	300,541
Property and equipment, net	24,238	33,487
Right-of-use lease asset	22,720
Internal use software development costs, net	15,189	14,570
Intangible assets, net	7,870	10,174
Other assets, non-current	2,125	1,240
TOTAL ASSETS	335,321	360,012
Current liabilities:
Accounts payable and accrued expenses	207,033	239,678
Lease liabilities, current	6,993
Other current liabilities	498	1,304
TOTAL CURRENT LIABILITIES	214,524	240,982
Lease liabilities, non-current	16,495
Other liabilities, non-current	179	1,017
TOTAL LIABILITIES	231,198	241,999
Commitments and contingencies (Note 10)
STOCKHOLDERS' EQUITY
Preferred stock, $0.00001 par value, 10,000 shares authorized at September 30, 2019 and December 31, 2018; 0 shares issued and outstanding at September 30, 2019 and December 31, 2018	0	0
Common stock, $0.00001 par value; 500,000 shares authorized at September 30, 2019 and December 31, 2018; 53,073 and 51,159 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively	1	1
Additional paid-in capital	447,314	433,877
Accumulated other comprehensive loss	(585)	(259)
Accumulated deficit	(342,607)	(315,606)
TOTAL STOCKHOLDERS' EQUITY	104,123	118,013
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 335,321	$ 360,012

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (usd per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (usd per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares, issued (in shares)	53,073,000	51,159,000
Common stock, shares, outstanding (in shares)	53,073,000	51,159,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 37,642,000	$ 29,729,000	$ 107,928,000	$ 83,253,000
Expenses:
Cost of revenue	13,869,000	14,687,000	44,070,000	44,514,000
Sales and marketing	11,040,000	10,654,000	33,151,000	34,046,000
Technology and development	10,293,000	9,299,000	29,848,000	29,038,000
General and administrative	9,121,000	9,355,000	29,428,000	33,340,000
Restructuring and other exit costs	0	0	0	3,440,000
Total expenses	44,323,000	43,995,000	136,497,000	144,378,000
Loss from operations	(6,681,000)	(14,266,000)	(28,569,000)	(61,125,000)
Other (income) expense:
Interest income, net	(218,000)	(232,000)	(625,000)	(777,000)
Other income	(48,000)	(206,000)	(236,000)	(626,000)
Foreign exchange gain, net	(296,000)	(120,000)	(138,000)	(363,000)
Total other income, net	(562,000)	(558,000)	(999,000)	(1,766,000)
Loss before income taxes	(6,119,000)	(13,708,000)	(27,570,000)	(59,359,000)
Provision (benefit) for income taxes	55,000	84,000	(569,000)	233,000
Net loss	$ (6,174,000)	$ (13,792,000)	$ (27,001,000)	$ (59,592,000)
Net loss per share:
Basic and Diluted (usd per share)	$ (0.12)	$ (0.27)	$ (0.52)	$ (1.19)
Weighted average shares used to compute net loss per share:
Basic and Diluted (in shares)	53,023	50,513	52,324	50,095

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (6,174)	$ (13,792)	$ (27,001)	$ (59,592)
Other comprehensive income (loss):
Unrealized gain on investments	0	9	2	15
Foreign currency translation adjustments	(292)	(99)	(328)	(223)
Other comprehensive loss	(292)	(90)	(326)	(208)
Comprehensive loss	$ (6,466)	$ (13,882)	$ (27,327)	$ (59,800)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance (in shares) at Dec. 31, 2017		50,239
Beginning Balance at Dec. 31, 2017	$ 164,611	$ 0	$ 418,354	$ 41	$ (253,784)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		9
Exercise of common stock options	6		6
Issuance of common stock related to RSU vesting (in shares)		51
Shares withheld related to net share settlement (in shares)		(19)
Shares withheld related to net share settlement	(40)		(40)
Stock-based compensation	4,689		4,689
Other comprehensive income/loss	204			204
Net loss	(27,816)				(27,816)
Ending Balance (in shares) at Mar. 31, 2018		50,280
Ending Balance at Mar. 31, 2018	141,654	$ 0	423,009	245	(281,600)
Beginning Balance (in shares) at Dec. 31, 2017		50,239
Beginning Balance at Dec. 31, 2017	164,611	$ 0	418,354	41	(253,784)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income/loss	(208)
Net loss	(59,592)
Ending Balance (in shares) at Sep. 30, 2018		50,751
Ending Balance at Sep. 30, 2018	117,752	$ 1	431,294	(167)	(313,376)
Beginning Balance (in shares) at Mar. 31, 2018		50,280
Beginning Balance at Mar. 31, 2018	141,654	$ 0	423,009	245	(281,600)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		40
Exercise of common stock options	39		39
Restricted stock awards, net (in shares)		(156)
Issuance of common stock related to employee stock purchase plan (in shares)		89
Issuance of common stock related to employee stock purchase plan	143		143
Issuance of common stock related to RSU vesting (in shares)		779
Issuance of common stock related to RSU vesting	1	$ 1
Shares withheld related to net share settlement (in shares)		(282)
Shares withheld related to net share settlement	(618)		(618)
Stock-based compensation	4,751		4,751
Other comprehensive income/loss	(322)			(322)
Net loss	(17,984)				(17,984)
Ending Balance (in shares) at Jun. 30, 2018		50,750
Ending Balance at Jun. 30, 2018	127,664	$ 1	427,324	(77)	(299,584)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		1
Stock-based compensation	3,970		3,970
Other comprehensive income/loss	(90)			(90)
Net loss	(13,792)				(13,792)
Ending Balance (in shares) at Sep. 30, 2018		50,751
Ending Balance at Sep. 30, 2018	$ 117,752	$ 1	431,294	(167)	(313,376)
Beginning Balance (in shares) at Dec. 31, 2018	51,159	51,159
Beginning Balance at Dec. 31, 2018	$ 118,013	$ 1	433,877	(259)	(315,606)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		76
Exercise of common stock options	251		251
Restricted stock awards, net (in shares)		(182)
Issuance of common stock related to RSU vesting (in shares)		1,171
Shares withheld related to net share settlement (in shares)		(459)
Shares withheld related to net share settlement	(1,835)		(1,835)
Stock-based compensation	4,514		4,514
Other comprehensive income/loss	94			94
Net loss	(12,546)				(12,546)
Ending Balance (in shares) at Mar. 31, 2019		51,765
Ending Balance at Mar. 31, 2019	$ 108,491	$ 1	436,807	(165)	(328,152)
Beginning Balance (in shares) at Dec. 31, 2018	51,159	51,159
Beginning Balance at Dec. 31, 2018	$ 118,013	$ 1	433,877	(259)	(315,606)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income/loss	(326)
Net loss	$ (27,001)
Ending Balance (in shares) at Sep. 30, 2019	53,073	53,073
Ending Balance at Sep. 30, 2019	$ 104,123	$ 1	447,314	(585)	(342,607)
Beginning Balance (in shares) at Mar. 31, 2019		51,765
Beginning Balance at Mar. 31, 2019	108,491	$ 1	436,807	(165)	(328,152)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		79
Exercise of common stock options	132		132
Issuance of common stock related to employee stock purchase plan (in shares)		118
Issuance of common stock related to employee stock purchase plan	477		477
Issuance of common stock related to RSU vesting (in shares)		1,022
Shares withheld related to net share settlement (in shares)		0
Shares withheld related to net share settlement	(12)		(12)
Stock-based compensation	4,949		4,949
Other comprehensive income/loss	(128)			(128)
Net loss	(8,281)				(8,281)
Ending Balance (in shares) at Jun. 30, 2019		52,984
Ending Balance at Jun. 30, 2019	105,628	$ 1	442,353	(293)	(336,433)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		83
Exercise of common stock options	146		146
Issuance of common stock related to RSU vesting (in shares)		6
Stock-based compensation	4,815		4,815
Other comprehensive income/loss	(292)			(292)
Net loss	$ (6,174)				(6,174)
Ending Balance (in shares) at Sep. 30, 2019	53,073	53,073
Ending Balance at Sep. 30, 2019	$ 104,123	$ 1	$ 447,314	$ (585)	$ (342,607)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
OPERATING ACTIVITIES:
Net loss	$ (27,001)	$ (59,592)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	24,841	26,355
Stock-based compensation	13,877	13,016
Loss on disposal of property and equipment	92	149
Provision for doubtful accounts	897	217
Accretion of available-for-sale securities	24	(374)
Non-cash lease expense	(469)
Unrealized foreign currency (gains) losses, net	(391)	(206)
Deferred income taxes	(748)	0
Changes in operating assets and liabilities:
Accounts receivable	32,149	10,318
Prepaid expenses and other assets	672	2,919
Accounts payable and accrued expenses	(34,018)	(14,415)
Other liabilities	(117)	(939)
Net cash provided by (used in) operating activities	9,808	(22,552)
INVESTING ACTIVITIES:
Purchases of property and equipment	(5,605)	(5,474)
Capitalized internal use software development costs	(6,000)	(6,569)
Investments in available-for-sale securities	0	(23,991)
Maturities of available-for-sale securities	7,500	55,650
Sales of available-for-sale securities	0	9,228
Net cash (used in) provided by investing activities	(4,105)	28,844
FINANCING ACTIVITIES:
Proceeds from exercise of stock options	529	45
Proceeds from issuance of common stock under employee stock purchase plan	477	143
Taxes paid related to net share settlement	(1,847)	(658)
Net cash used in financing activities	(841)	(470)
EFFECT OF EXCHANGE RATE CHANGES ON CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(192)	(110)
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	4,670	5,712
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period	80,452	76,642
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — End of period	85,122	82,354
SUPPLEMENTAL DISCLOSURES OF OTHER CASH FLOW INFORMATION:
Cash paid for income taxes	300	272
Cash paid for interest	46	46
Capitalized assets financed by accounts payable and accrued expenses	2,005	3
Capitalized stock-based compensation	401	$ 394
Operating lease right-of-use assets obtained in exchange for new operating lease liabilities	$ 13,074

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	Organization and Summary of Significant Accounting Policies Company Overview The Rubicon Project, Inc., or Rubicon Project (the "Company"), was formed on April 20, 2007 in Delaware and began operations in April 2007. The Company is headquartered in Los Angeles, California. The Company provides a technology solution to automate the purchase and sale of digital advertising inventory for buyers and sellers. The Company's platform features applications and services for digital advertising sellers, including websites, mobile applications and other digital media properties, and their representatives, to sell their digital advertising inventory; applications and services for buyers, including advertisers, agencies, agency trading desks, and demand side platforms, or DSPs, to buy digital advertising inventory; and a marketplace over which such transactions are executed. In the second quarter of 2019, the Company announced the beta program for Demand Manager, which helps sellers effectively monetize their advertising inventory by making it easier to deploy, configure, and optimize Prebid-based header bidding solutions. Prebid is a free and open source suite of software products designed by advertising community developers to enable publishers to implement header bidding on their websites and from within their apps. Together, these features power and enhance a comprehensive, transparent, independent advertising marketplace that brings buyers and sellers together and facilitates intelligent decision making and automated transaction execution for the digital advertising inventory managed on the Company's platform. The Company's clients include many of the world's leading publishers of websites and mobile applications and buyers of digital advertising inventory. Advertising inventory takes different forms, referred to as advertising units, is purchased and sold through different transactional methods, and allows advertising content to be presented to consumers through different channels. The Company's solution enables buyers and sellers to purchase and sell: • a comprehensive range of advertising units, including display, audio, and video; • that are transacted through real-time bidding, which includes (i) direct sale of premium inventory, which the Company refers to as private marketplace, or PMP, and (ii) open auction bidding, which the Company refers to as open marketplace, or OMP; and • that are displayed across digital channels, including mobile web, mobile application, and desktop, as well as across various out-of-home channels, such as digital billboards. Risks and Uncertainties The Company operates in the rapidly changing advertising industry and has faced demands by ad tech buyers for more efficiency and lower costs, changes in bidding technologies, and increased competition. The Company has adjusted its pricing model, which has reduced margins, and has lowered its expense structure to address these changes in the industry, resulting in net operating losses. The Company continues to incur net operating losses, despite having increased revenues and reduced costs. The Company must continue to increase revenues and/or manage costs in order to compensate for reduced margins, or it may not be able to grow its business and may continue to operate at a loss, depleting its cash resources and liquidity. If the Company continues to experience significant operating losses in the future, the Company may require additional liquidity to fund its operations. Basis of Presentation and Summary of Significant Accounting Policies The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States Generally Accepted Accounting Principles, or GAAP, for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair statement of the results for the interim period presented have been included. Operating results for the nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for any future interim period, the year ending December 31, 2019 , or for any future year. The condensed consolidated balance sheet at December 31, 2018 has been derived from the audited financial statements at that date, but does not include all of the disclosures required by GAAP. The accompanying condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes thereto for the year ended December 31, 2018 included in its 2018 Annual Report on Form 10-K. The Company adopted Accounting Standards Codification Topic 842 ("ASC 842")— Leases on January 1, 2019 using a modified retrospective approach. The adoption of this standard impacted only the financial statements included as of September 30, 2019 and for the three and nine months ended September 30, 2019 . See below for additional information regarding the Company's adoption of ASC 842. Aside from the adoption of ASC 842, there have been no significant changes in the Company's accounting policies from those disclosed in its audited consolidated financial statements and notes thereto for the year ended December 31, 2018 included in its Annual Report on Form 10-K. Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported and disclosed financial statements and accompanying footnotes. Actual results could differ materially from these estimates. Adoption of ASC 842 On January 1, 2019, the Company adopted ASC 842, which requires the recognition of the right-of-use assets, or ROU assets, and related lease liabilities on the balance sheet using a modified retrospective approach. The consolidated financial statements related to periods prior to January 1, 2019 were not restated, and continue to be reported under ASC Topic 840— Leases ("ASC 840"), which did not require the recognition of operating lease liabilities on the balance sheet. As a result, the consolidated financial statements related to periods prior to January 1, 2019 are not entirely comparative with current and future periods. As permitted under ASC 842, the Company elected several practical expedients that permit the Company to not reassess (1) whether existing contracts are or contain a lease, (2) the classification of existing leases, and (3) whether previously capitalized costs continue to qualify as initial indirect costs. In addition, the Company has elected not to recognize short-term leases on our balance sheet, nor separate lease and non-lease components for our data center leases. In addition, we utilized the portfolio approach to group leases with similar characteristics and did not use hindsight to determine lease term. In addition to the leases previously reported under ASC 840, the Company also reviewed its data center agreements to identify non-lease components that should not be included in the lease liability and lease expense under ASC 842. Certain fixed non-lease components of data center leases, primarily fixed minimum power commitments, have been included in the lease liability and ROU asset as the Company has elected the practical expedient for its data centers to not separate the lease and non-lease components; however, variable components have not been included. For identified leases, the Company used its incremental borrowing rate to discount the related future payment obligations as of January 1, 2019 to determine its lease liability as of adoption. As of the adoption date, the Company recognized a lease liability of $15.6 million and a corresponding ROU asset of $14.3 million ; there was no equity impact from the adoption. The difference between the lease liability and the ROU asset primarily represents the existing deferred rent liabilities balances before adoption, resulting from historical straight-lining of operating leases, which was effectively reclassified upon adoption to reduce the measurement of the ROU asset. The Company records rent expense for operating leases, including leases of office locations, data centers, and equipment, on a straight-line basis over the lease term. The straight-line calculation of rent expense includes rent escalations on certain leases, as well as lease incentives provided by the landlords, including payments for leasehold improvements and rent-free periods. The Company begins recognition of rent expense on the commencement date, which is generally the date that the asset is made available for use. The lease liability is included in lease liabilities, current and lease liabilities, non-current within the condensed consolidated balance sheet, which are reduced as lease related payments are made. The ROU asset is amortized on a periodic basis over the expected term of the lease. See Note 11 for additional information. Recent Accounting Pronouncements Under the Jumpstart Our Business Startups Act, or the JOBS Act, the Company meets the definition of an emerging growth company through the end of 2019. The Company has irrevocably elected to opt out of the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act. In March 2019, the Financial Accounting Standards Board issued ASU 2019-01— Leases (Topic 842): Codification Improvements

Net Income (Loss) Per Share

Net Income (Loss) Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	Net Income (Loss) Per Share The following table presents the basic and diluted net loss per share: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands, except per share data) Basic and Diluted EPS: Net loss $ (6,174 ) $ (13,792 ) $ (27,001 ) $ (59,592 ) Weighted-average common shares outstanding 53,029 50,750 52,349 50,482 Weighted-average unvested restricted stock (6 ) (237 ) (25 ) (387 ) Weighted-average common shares outstanding used to compute net loss per share 53,023 50,513 52,324 50,095 Basic and diluted net loss per share $ (0.12 ) $ (0.27 ) $ (0.52 ) $ (1.19 ) The following weighted-average shares have been excluded from the calculation of diluted net loss per share attributable to common stockholders for each period presented because they are anti-dilutive: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands) (in thousands) Options to purchase common stock 1,078 162 732 72 Unvested restricted stock awards — 208 16 232 Unvested restricted stock units 5,168 2,324 3,911 1,709 ESPP 48 94 35 64 Total shares excluded from net loss per share 6,294 2,788 4,694 2,077

Revenues

Revenues	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenues	Revenues The Company generates revenue from transactions where it provides a platform for the purchase and sale of digital advertising inventory. The Company’s advertising automation solution is a marketplace for sellers of digital advertising inventory (providers of websites, mobile applications and other digital media properties, and their representatives) and buyers of digital advertising inventory (including advertisers, agencies, agency trading desks, and demand-side platforms). This solution incorporates proprietary machine-learning algorithms, sophisticated data processing, high-volume storage, detailed analytics capabilities, and a distributed infrastructure. Together, these features form the basis for the Company’s automated advertising solution that brings buyers and sellers together and facilitates intelligent decision-making and automated transaction execution for the digital advertising inventory managed on the Company's platform. Digital advertising inventory is created when consumers access sellers’ content. Sellers provide digital advertising inventory to the Company’s platform in the form of advertising requests, or ad requests. When the Company receives ad requests from sellers, it sends bid requests to buyers, which enable buyers to bid on sellers’ digital advertising inventory. Winning bids can create advertising, or paid impressions, for the seller to present to the consumer. The total volume of spending between buyers and sellers on the Company’s platform is referred to as advertising spend. The Company keeps a percentage of that advertising spend as a fee, and remits the remainder to the seller. The fee that the Company retains from the gross advertising spend on its platform is recognized as revenue. The fee earned on each transaction is based on the pre-existing agreement between the Company and the seller and the clearing price of the winning bid. The Company recognizes revenue upon fulfillment of its performance obligation to a client, which occurs at the point in time an ad renders and is counted as a paid impression, subject to an underlying agreement existing with the client and a fixed or determinable transaction price. Performance obligations for all transactions are satisfied, and the corresponding revenue is recognized, at a distinct point in time when an ad renders. The Company does not have arrangements with multiple performance obligations. The Company considers the following when determining if a contract exists under which the performance obligations have been satisfied: (i) contract approval by all parties, (ii) identification of each party’s rights regarding the goods or services to be transferred, (iii) specified payment terms, (iv) commercial substance of the contract, and (v) collectability of substantially all of the consideration is probable. The Company has determined that it does not act as the principal in the purchase and sale of digital advertising inventory because it does not have control of the digital advertising inventory and does not set prices agreed upon within the auction marketplace, and therefore reports revenue on a net basis. Payment terms are specified in agreements between the Company and the buyers and sellers on its exchange platform. The Company generally bills buyers at the end of each month for the full purchase price of impressions filled in that month. The Company recognizes volume discounts as a reduction of revenue as they are incurred. Specific payment terms may vary by agreement, but are generally seventy-five days or less. The Company's accounts receivable are recorded at the amount of gross billings to buyers, net of allowances for the amounts the Company is responsible to collect. The Company's accounts payable related to amounts due to sellers are recorded at the net amount payable to sellers (see Note 5). Accordingly, both accounts receivable and accounts payable appear large in relation to revenue reported on a net basis. The following table presents our revenue by channel for the three and nine months ended September 30, 2019 and 2018 : Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands, except percentages) Channel: Desktop $ 15,936 42 % $ 12,481 42 % $ 47,745 44 % $ 40,453 49 % Mobile 21,706 58 17,248 58 60,183 56 42,800 51 Total $ 37,642 100 % $ 29,729 100 % $ 107,928 100 % $ 83,253 100 % The following table presents our revenue disaggregated by geographic location, based on the location of the Company's sellers: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands) (in thousands) United States $ 26,378 $ 19,731 $ 73,654 $ 54,201 International 11,264 9,998 34,274 29,052 Total $ 37,642 $ 29,729 $ 107,928 $ 83,253

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Recurring Fair Value Measurements Fair value represents 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. Observable inputs are based on market data obtained from independent sources. The fair value hierarchy is based on the following three levels of inputs, of which the first two are considered observable and the last one is considered unobservable: • Level 1 – Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. • Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. • Level 3 – Unobservable inputs. The table below sets forth a summary of financial instruments that are measured at fair value on a recurring basis at September 30, 2019 : Total Quoted Prices in Significant Other Significant (in thousands) Cash equivalents $ 13,447 $ 13,447 $ — $ — The table below sets forth a summary of financial instruments that are measured at fair value on a recurring basis at December 31, 2018 : Total Quoted Prices in Significant Other Significant (in thousands) Cash equivalents $ 13,692 $ 13,692 $ — $ — U.S. Treasury, government and agency debt securities $ 7,524 $ 7,524 $ — $ — At September 30, 2019 and December 31, 2018 , cash equivalents of $13.4 million and $13.7 million , respectively, consisted of money market funds and commercial paper, with original maturities of three months or less. The carrying amounts of cash equivalents are classified as Level 1 or Level 2 depending on whether or not their fair values are based on quoted market prices for identical securities that are traded in an active market. Corporate debt securities (which are included in marketable securities on the balance sheet) with fair values derived from similar securities rather than based on quoted market prices for identical securities, are classified as Level 2 as well. The fair values of the Company's U.S. treasury, government and agency debt securities are based on quoted market prices and classified as Level 1, and are included within marketable securities.

Other Balance Sheet Amounts

Other Balance Sheet Amounts	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other Balance Sheet Amounts	Other Balance Sheet Amounts Investments in marketable securities as of December 31, 2018 consisted of the following: Amortized Gross Gross Fair (in thousands) Available-for-sale—short-term: U.S. Treasury, government and agency debt securities $ 7,526 $ — $ (2 ) $ 7,524 The Company had no available-for-sale securities as of September 30, 2019 . For the three and nine months ended September 30, 2019 , there were no realized gains (losses) and there were no unrealized holding gains (losses) reclassified out of accumulated other comprehensive loss into the condensed consolidated statements of operations for the sale of available-for-sale investments. For the nine months ended September 30, 2018 , the Company sold $9.2 million of available-for-sale investments, on which the realized gains were de minimis and there were no unrealized holding gains (losses) reclassified out of accumulated other comprehensive loss into the condensed consolidated statements of operations. Accounts payable and accrued expenses included the following: September 30, 2019 December 31, 2018 (in thousands) Accounts payable—seller $ 195,467 $ 230,423 Accounts payable—trade 5,463 3,122 Accrued employee-related payables 6,103 6,133 Total $ 207,033 $ 239,678 There was no restricted cash as of September 30, 2019 and December 31, 2018 .

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible Assets The Company’s intangible assets as of September 30, 2019 and December 31, 2018 included the following: September 30, 2019 December 31, 2018 (in thousands) Amortizable intangible assets: Developed technology $ 16,878 $ 16,878 Non-compete agreements — 690 Trademarks 20 20 Total identifiable intangible assets, gross 16,898 17,588 Accumulated amortization—intangible assets: Developed technology (9,008 ) (6,888 ) Non-compete agreements — (506 ) Trademarks (20 ) (20 ) Total accumulated amortization—intangible assets (9,028 ) (7,414 ) Total identifiable intangible assets, net $ 7,870 $ 10,174 Amortization of intangible assets for the three months ended September 30, 2019 and 2018 was $0.7 million and $0.8 million , respectively, and $2.3 million and $2.4 million for the nine months ended September 30, 2019 and 2018 , respectively. The estimated remaining amortization expense associated with the Company's intangible assets was as follows as of September 30, 2019 : Fiscal Year Amount (in thousands) Remaining 2019 $ 706 2020 2,826 2021 2,826 2022 1,512 2023 — Thereafter — Total $ 7,870

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company’s equity incentive plans provide for the grant of equity awards, including non-statutory or incentive stock options, restricted stock awards ("RSAs"), and restricted stock units ("RSUs"), to the Company's employees, officers, directors, and consultants. The Company's board of directors administers the plans. Outstanding options vest based upon continued service at varying rates, but generally over four years from issuance with 25% vesting after one year of service and the remainder vesting monthly thereafter. RSAs and RSUs vest at varying rates, typically approximately 25% vesting after approximately one year of service and the remainder vesting semi-annually thereafter, but with certain retention grants vesting 50% on each of the first and second anniversaries of the grant date. Options, RSAs, and RSUs granted under the plans accelerate under certain circumstances for certain participants upon a change in control, as defined in the governing plan. An aggregate of 4,377,171 shares remained available for future grants at September 30, 2019 under the plans. Stock Options A summary of stock option activity for the nine months ended September 30, 2019 is as follows: Shares Under Option Weighted- Average Exercise Price Weighted- Average Contractual Life Aggregate Intrinsic Value (in thousands) (in thousands) Outstanding at December 31, 2018 3,488 $ 7.06 Granted 1,184 $ 4.98 Exercised (239 ) $ 2.21 Expired (36 ) $ 14.03 Forfeited (73 ) $ 2.62 Outstanding at September 30, 2019 4,324 $ 6.77 7.24 years $ 14,566 Exercisable at September 30, 2019 2,370 $ 8.71 5.94 years $ 5,889 The total intrinsic values of options exercised during the nine months ended September 30, 2019 was $1.3 million . At September 30, 2019 , the Company had unrecognized employee stock-based compensation expense relating to nonvested stock options of approximately $4.6 million , which is expected to be recognized over a weighted-average period of 2.75 years . The weighted-average grant date fair value per share of stock options granted during the nine months ended September 30, 2019 was $2.85 . Total fair value of options vested during the nine months ended September 30, 2019 was $1.3 million . The Company estimates the fair value of stock options that contain service and/or performance conditions using the Black-Scholes option pricing model. The weighted-average input assumptions used by the Company were as follows: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 Expected term (in years) N/A 5.4 6.1 5.7 Risk-free interest rate N/A 2.75 % 2.51 % 2.53 % Expected volatility N/A 55 % 60 % 57 % Dividend yield N/A — % — % — % Restricted Stock Awards A summary of RSA activity for the nine months ended September 30, 2019 is as follows: Number of Shares Weighted-Average Grant Date Fair Value (in thousands) Nonvested shares of restricted stock awards outstanding at December 31, 2018 197 $ 12.06 Granted — $ — Canceled (182 ) $ 11.92 Vested (10 ) $ 13.84 Nonvested shares of restricted stock awards outstanding at September 30, 2019 5 $ 13.49 The aggregate fair value of restricted stock with service conditions that vested during the nine months ended September 30, 2019 was $0.1 million . At September 30, 2019 , the Company had unrecognized stock-based compensation expense for RSAs with service conditions of $37.9 thousand , which is expected to be recognized over a weighted-average period of 0.6 years . Restricted Stock Units A summary of RSU activity for the nine months ended September 30, 2019 is as follows: Number of Shares Weighted-Average Grant Date Fair Value (in thousands) Nonvested restricted stock units outstanding at December 31, 2018 6,100 $ 3.56 Granted 4,856 $ 4.77 Canceled (404 ) $ 3.74 Vested (2,199 ) $ 3.39 Nonvested restricted stock units outstanding at September 30, 2019 8,353 $ 4.30 The weighted-average grant date fair value per share of RSUs granted during the nine months ended September 30, 2019 was $4.77 , which included 1.6 million RSUs that vest 50% annually over two years . The aggregate fair value of RSUs that vested during nine months ended September 30, 2019 was $11.3 million . At September 30, 2019 , the intrinsic value of nonvested RSUs was $72.8 million . At September 30, 2019 , the Company had unrecognized stock-based compensation expense relating to nonvested RSUs of approximately $26.5 million , which is expected to be recognized over a weighted-average period of 2.3 years . Employee Stock Purchase Plan In November 2013, the Company adopted the Company's 2014 Employee Stock Purchase Plan ("ESPP"). The ESPP is designed to enable eligible employees to periodically purchase shares of the Company's common stock at a discount through payroll deductions of up to 10% of their eligible compensation, subject to any plan limitations. At the end of each six-month offering period, employees are able to purchase shares at a price per share equal to 85% of the lower of the fair market value of the Company's common stock on the first trading day of the offering period or on the last trading day of the offering period. Offering periods generally commence and end in May and November of each year. As of September 30, 2019 , the Company has reserved 2,001,256 shares of its common stock for issuance under the ESPP. The ESPP has an evergreen provision pursuant to which the share reserve will automatically increase on January 1 st of each year in an amount equal to 1% of the total number of shares of capital stock outstanding on December 31 st of the preceding calendar year, although the Company’s board of directors may provide for a lesser increase, or no increase, in any year. Stock-Based Compensation Expense Total stock-based compensation expense recorded in the condensed consolidated statements of operations was as follows: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands) (in thousands) Cost of revenue $ 110 $ 72 $ 308 $ 256 Sales and marketing 1,378 1,187 4,182 3,530 Technology and development 1,157 691 3,382 2,163 General and administrative 2,068 1,910 6,005 6,669 Restructuring and other exit costs — — — 398 Total stock-based compensation expense $ 4,713 $ 3,860 $ 13,877 $ 13,016

Restructuring and Other Exit Co

Restructuring and Other Exit Costs	9 Months Ended
	Sep. 30, 2019
Restructuring and Related Activities [Abstract]
Restructuring and Other Exit Costs	Restructuring and Other Exit Costs As part of its on-going efforts to control costs and create efficiencies, the Company undertook restructuring events in 2018 to streamline operations, prioritize resources for growth initiatives and increase profitability. Restructuring and other exit costs of $3.4 million were incurred during the nine months ended September 30, 2018 related to severance and one-time termination benefit costs. There were no restructuring charges incurred during the three months ended September 30, 2018 . The following table summarizes restructuring and other exit cost activity for the nine months ended September 30, 2018 (in thousands): Accrued restructuring and other exit costs at January 1, 2018 $ — Restructuring and other exit costs 3,440 Cash paid for restructuring and other exit costs (2,884 ) Non-cash stock-based compensation for restructuring and other exit costs (398 ) Accrued restructuring and other exit costs at September 30, 2018 $ 158 As of December 31, 2018, the Company had $0.1 million accrued restructuring and other exit costs remaining. No restructuring and other exit costs were incurred during the three and nine months ended September 30, 2019 , and all remaining accrued costs associated with the 2018 restructuring events were paid in the first quarter of 2019.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes In determining quarterly provisions for income taxes, the Company uses the annual estimated effective tax rate applied to the actual year-to-date income. The Company's annual estimated effective tax rate differs from the statutory rate primarily as a result of state taxes, foreign taxes, nondeductible stock option expenses, and changes in the Company's valuation allowance. The Company recorded an income tax expense of $0.1 million and an income tax benefit of $0.6 million for the three and nine months ended September 30, 2019 , respectively, and income tax expenses of $0.1 million and $0.2 million for the three and nine months ended September 30, 2018 , respectively. The tax provision for the three and nine months ended September 30, 2019 is primarily the result of the release of a foreign valuation allowance resulting from a change to a cost plus arrangement for a foreign subsidiary, the domestic valuation allowance, and the tax liability associated with the foreign subsidiaries. On December 22, 2017, the U.S. government enacted the Tax Cuts and Jobs Act (the “Tax Act”). The Tax Act includes significant changes to the U.S. corporate income tax system including a federal corporate rate reduction from 34% to 21%. For additional information and a discussion of the impact of the Tax Act on the Company, refer to Note 15 of the "Notes to Consolidated Financial Statements" within our Annual Report on Form 10-K for December 31, 2018. Due to uncertainty as to the realization of benefits from the Company's domestic and certain international deferred tax assets, including net operating loss carryforwards and research and development tax credits, the Company has a full valuation allowance reserved against such assets. The Company intends to continue to maintain a full valuation allowance on the deferred tax assets until there is sufficient evidence to support the reversal of all or some portion of these allowances. There were no material changes to the Company's unrecognized tax benefits in the nine months ended September 30, 2019

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments As of September 30, 2019 and December 31, 2018 , the Company had $2.5 million and $2.9 million , respectively, of letters of credit associated with office leases available for borrowing, on which there were no outstanding borrowings as of either date. The Company also has operating lease agreements, discussed in more detail in Note 11. Guarantees and Indemnification The Company’s agreements with sellers, buyers, and other third parties typically obligate it to provide indemnity and defense for losses resulting from claims of intellectual property infringement, damages to property or persons, business losses, or other liabilities. Generally, these indemnity and defense obligations relate to the Company’s own business operations, obligations, and acts or omissions. However, under some circumstances, the Company agrees to indemnify and defend contract counterparties against losses resulting from their own business operations, obligations, and acts or omissions, or the business operations, obligations, and acts or omissions of third parties. For example, because the Company’s business interposes the Company between buyers and sellers in various ways, buyers often require the Company to indemnify them against acts and omissions of sellers, and sellers often require the Company to indemnify them against acts and omissions of buyers. In addition, the Company’s agreements with sellers, buyers, and other third parties typically include provisions limiting the Company’s liability to the counterparty, and the counterparty’s liability to the Company. These limits sometimes do not apply to certain liabilities, including indemnity obligations. These indemnity and limitation of liability provisions generally survive termination or expiration of the agreements in which they appear. The Company has also entered into indemnification agreements with its directors, executive officers, and certain other 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, officers, or employees. No material demands have been made upon the Company to provide indemnification under such agreements and there are no claims that the Company is aware of that could have a material effect on the Company’s condensed consolidated financial statements. Litigation The Company and its subsidiaries may from time to time be parties to legal or regulatory proceedings, lawsuits and other claims incident to their business activities and to the Company’s status as a public company. Such routine matters may include, among other things, assertions of contract breach or intellectual property infringement, claims for indemnity arising in the course of the Company’s business, regulatory investigations or enforcement proceedings, and claims by persons whose employment has been terminated. Such matters are subject to many uncertainties, and outcomes are not predictable with assurance. Consequently, management is unable to ascertain the ultimate aggregate amount of monetary liability, amounts which may be covered by insurance or recoverable from third parties, or the financial impact with respect to such matters as of September 30, 2019 . However, based on management’s knowledge as of September 30, 2019 , management believes that the final resolution of these matters known at such date, individually and in the aggregate, will not have a material adverse effect upon the Company’s condensed consolidated financial position, results of operations or cash flows. Employment Contracts

Lease Obligations

Lease Obligations	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lease Obligations	Lease Obligations The Company adopted ASC 842 as of January 1, 2019. As part of the implementation, the Company recognized its lease liabilities, including the current and non-current portions, within its condensed consolidated balance sheet as of the adoption date, which represents the present value of the Company’s obligation related to the estimated future lease payments. The Company also recognized a right-of-use asset, or ROU asset, which represents the right to use the leased asset over the period of the lease. The ROU asset was calculated as the lease liability less any asset or liability balances that existed at the time of adoption. The lease term is generally specified in the lease agreement, however certain agreements provide for lease term extensions or early termination options. To determine the period for the estimated future lease payments, the Company evaluates whether it is reasonably certain that it will exercise the option at the commencement date and periodically thereafter. Certain data center lease agreements include one year extension options or month-to-month extension options, and one or more of these extensions have been assumed for each lease that the Company believes to be an integral part of our business in the near term. The lease terms of the Company’s operating leases generally range from one year to ten years , and the weighted average remaining lease term of leases included in the lease liability is 6.28 years as of September 30, 2019 . To determine the estimated future lease payments, the Company reviews each of its lease agreements to identify the various payment components. For real estate and equipment leases, the Company includes only the actual lease components in its determination of future lease payments, and for its data center leases, includes both the fixed lease and non-lease components in the estimated future lease payments. This typically includes a fixed minimum power commitment that is included in the data center agreements, but it does not include any variable or usage-based additional charges. Once the estimated future lease payments are determined, the Company uses a discount rate to calculate the present value of the future lease payments. As of September 30, 2019 , a weighted average discount rate of 4.73% has been applied to the remaining lease payments to calculate the lease liabilities included within the condensed consolidated balance sheet. This represents the incremental borrowing rate the Company would be subject to on borrowings from its available revolving debt agreement (See Note 12). For the three and nine months ended September 30, 2019 , the Company recognized $ 2.0 million and $5.7 million , respectively, of lease expense under ASC 842, which included operating lease expenses associated with leases included in the lease liability and ROU asset on the condensed consolidated balance sheet. In addition, for the three and nine months ended September 30, 2019 , the Company recognized $0.1 million and $0.5 million , respectively, of lease expense related to short-term leases that are not included in the ROU asset or lease liability balances. For the three and nine months ended September 30, 2018 , the Company recognized rental expenses of $3.2 million and $9.7 million , respectively, under ASC 840, which included expenses related to short-term leases, and also included certain non-lease components including variable capacity related expenses at the data centers. The Company also received rental income of $48.4 thousand and $0.2 million for real estate leases for which it subleases the property to a third party during the three months ended September 30, 2019 and 2018 , respectively, and $0.2 million and $0.6 million for the nine months ended September 30, 2019 and 2018 , respectively. The maturity of the Company's lease liabilities were as follows (in thousands): Fiscal Year Remaining 2019 $ 1,932 2020 7,905 2021 4,348 2022 2,284 2023 1,968 Thereafter 8,491 Total lease payments (undiscounted) 26,928 Less: imputed interest (3,440 ) Lease liabilities—total (discounted) $ 23,488 In addition to the leases included in these condensed consolidated financial statements, the Company entered into a lease agreement for an office location in New Jersey during the first half of 2019 that has not yet commenced as of September 30, 2019 . The Company anticipates the recognition of approximately $0.4 million

Debt

Debt	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt In September 2018, the Company amended and restated its loan and security agreement with Silicon Valley Bank ("SVB") (the "Loan Agreement"). The Loan Agreement provides a senior secured revolving credit facility of up to $40.0 million with a maturity date of September 26, 2020. The Company incurred $0.1 million of debt issuance fees that were capitalized and are being amortized over the term of the Loan Agreement. An unused revolver fee in the amount of 0.15% per annum of the average unused portion of the revolver line is charged and is payable monthly in arrears. The Company may elect for advances to bear interest calculated by reference to prime or LIBOR. If the Company elects LIBOR, amounts outstanding under the amended credit facility bear interest at a rate per annum equal to (a) LIBOR plus 2.50% if a streamline period applies or (b) LIBOR plus 4.00% if a streamline period does not apply. If the Company elects prime, advances bear interest at a rate of (a) prime plus 0.50% if a streamline period applies or (b) prime plus 2.00% if a streamline period does not apply. A streamline period is any period during which an event of default does not exist and the Company's Adjusted Quick Ratio (as defined in the Loan Agreement) is at least 1.05 for each day in the preceding month. The Loan Agreement is collateralized by security interests in substantially all of the Company's assets. Subject to certain exceptions, the Loan Agreement restricts the Company's ability to, among other things, pay dividends, sell assets, make changes to the nature of the business, engage in mergers or acquisitions, incur, assume or permit to exist, additional indebtedness and guarantees, create or permit to exist, liens, make distributions or redeem or repurchase capital stock, or make other investments, engage in transactions with affiliates, make payments with respect to subordinated debt, and enter into certain transactions without the consent of the financial institution. If a streamline period is not in effect, the Company is required to maintain a lockbox arrangement where clients' payments received in the lockbox will immediately reduce the amounts outstanding on the credit facility. The Loan Agreement requires the Company to comply with financial covenants, including a minimum Adjusted Quick Ratio and the achievement of certain Adjusted EBITDA targets. On a monthly basis, or quarterly if there were no advances outstanding during the calendar quarter, the Company is required to maintain a minimum Adjusted Quick Ratio of: (i) 1.00 if the trailing six month Adjusted EBITDA is $0 or less, or (ii) 0.90 if the trailing six month Adjusted EBITDA is greater than $0 . If the Company’s Adjusted Quick Ratio is 1.05 or greater, a streamline period applies. As of September 30, 2019 , the Company's Adjusted Quick Ratio was 1.15 , which is in compliance with its covenant requirement and is higher than the minimum Adjusted Quick Ratio required to qualify for a streamline period. The Company must also maintain the following trailing twelve month Adjusted EBITDA targets as of the end of each quarter as follows: (1) September 30, 2018 through June 30, 2019 Adjusted EBITDA must be within 20% of the Adjusted EBITDA projections that were delivered to Silicon Valley Bank; (2) September 30, 2019 Adjusted EBITDA of $1 or greater; and (3) December 31, 2019 and thereafter, Adjusted EBITDA of $5.0 million or greater. As of September 30, 2019 , the Company was in compliance with the Adjusted EBITDA covenant. The Loan Agreement also includes customary representations and warranties, affirmative covenants, and events of default, including events of default upon a change of control and material adverse change (as defined in the Loan Agreement). Following an event of default, SVB would be entitled to, among other things, accelerate payment of amounts due under the credit facility and exercise all rights of a secured creditor. As of September 30, 2019 , there were no amounts outstanding under the Loan Agreement. Future availability under the credit facility is dependent on several factors including the available borrowing base and compliance with future covenant requirements.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On October 21, 2019, the Company acquired RTK.io for cash consideration of $11 million . RTK.io is a provider of header bidding solutions that have much in common with the Company’s Demand Manager product, including a foundation in Prebid, the advertising technology industry's open source framework. The Company plans to integrate the two solutions to extend its Demand Manager product portfolio and client base, and to add talented header bidding experts and Prebid developers to its team. The initial accounting for the acquisition is expected to be completed by December 31, 2019.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States Generally Accepted Accounting Principles, or GAAP, for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair statement of the results for the interim period presented have been included. Operating results for the nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for any future interim period, the year ending December 31, 2019 , or for any future year. The condensed consolidated balance sheet at December 31, 2018 has been derived from the audited financial statements at that date, but does not include all of the disclosures required by GAAP. The accompanying condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes thereto for the year ended December 31, 2018 included in its 2018 Annual Report on Form 10-K. The Company adopted Accounting Standards Codification Topic 842 ("ASC 842")— Leases on January 1, 2019 using a modified retrospective approach. The adoption of this standard impacted only the financial statements included as of September 30, 2019 and for the three and nine months ended September 30, 2019 . See below for additional information regarding the Company's adoption of ASC 842. Aside from the adoption of ASC 842, there have been no significant changes in the Company's accounting policies from those disclosed in its audited consolidated financial statements and notes thereto for the year ended December 31, 2018
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported and disclosed financial statements and accompanying footnotes. Actual results could differ materially from these estimates.
Adoption of ASC 842 and Recent Accounting Pronouncements	Adoption of ASC 842 On January 1, 2019, the Company adopted ASC 842, which requires the recognition of the right-of-use assets, or ROU assets, and related lease liabilities on the balance sheet using a modified retrospective approach. The consolidated financial statements related to periods prior to January 1, 2019 were not restated, and continue to be reported under ASC Topic 840— Leases ("ASC 840"), which did not require the recognition of operating lease liabilities on the balance sheet. As a result, the consolidated financial statements related to periods prior to January 1, 2019 are not entirely comparative with current and future periods. As permitted under ASC 842, the Company elected several practical expedients that permit the Company to not reassess (1) whether existing contracts are or contain a lease, (2) the classification of existing leases, and (3) whether previously capitalized costs continue to qualify as initial indirect costs. In addition, the Company has elected not to recognize short-term leases on our balance sheet, nor separate lease and non-lease components for our data center leases. In addition, we utilized the portfolio approach to group leases with similar characteristics and did not use hindsight to determine lease term. In addition to the leases previously reported under ASC 840, the Company also reviewed its data center agreements to identify non-lease components that should not be included in the lease liability and lease expense under ASC 842. Certain fixed non-lease components of data center leases, primarily fixed minimum power commitments, have been included in the lease liability and ROU asset as the Company has elected the practical expedient for its data centers to not separate the lease and non-lease components; however, variable components have not been included. For identified leases, the Company used its incremental borrowing rate to discount the related future payment obligations as of January 1, 2019 to determine its lease liability as of adoption. As of the adoption date, the Company recognized a lease liability of $15.6 million and a corresponding ROU asset of $14.3 million ; there was no equity impact from the adoption. The difference between the lease liability and the ROU asset primarily represents the existing deferred rent liabilities balances before adoption, resulting from historical straight-lining of operating leases, which was effectively reclassified upon adoption to reduce the measurement of the ROU asset. The Company records rent expense for operating leases, including leases of office locations, data centers, and equipment, on a straight-line basis over the lease term. The straight-line calculation of rent expense includes rent escalations on certain leases, as well as lease incentives provided by the landlords, including payments for leasehold improvements and rent-free periods. The Company begins recognition of rent expense on the commencement date, which is generally the date that the asset is made available for use. The lease liability is included in lease liabilities, current and lease liabilities, non-current within the condensed consolidated balance sheet, which are reduced as lease related payments are made. The ROU asset is amortized on a periodic basis over the expected term of the lease. See Note 11 for additional information. Recent Accounting Pronouncements Under the Jumpstart Our Business Startups Act, or the JOBS Act, the Company meets the definition of an emerging growth company through the end of 2019. The Company has irrevocably elected to opt out of the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act. In March 2019, the Financial Accounting Standards Board issued ASU 2019-01— Leases (Topic 842): Codification Improvements

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Schedule of Net Loss Per Share, Basic and Diluted	The following table presents the basic and diluted net loss per share: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands, except per share data) Basic and Diluted EPS: Net loss $ (6,174 ) $ (13,792 ) $ (27,001 ) $ (59,592 ) Weighted-average common shares outstanding 53,029 50,750 52,349 50,482 Weighted-average unvested restricted stock (6 ) (237 ) (25 ) (387 ) Weighted-average common shares outstanding used to compute net loss per share 53,023 50,513 52,324 50,095 Basic and diluted net loss per share $ (0.12 ) $ (0.27 ) $ (0.52 ) $ (1.19 )
Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share	The following weighted-average shares have been excluded from the calculation of diluted net loss per share attributable to common stockholders for each period presented because they are anti-dilutive: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands) (in thousands) Options to purchase common stock 1,078 162 732 72 Unvested restricted stock awards — 208 16 232 Unvested restricted stock units 5,168 2,324 3,911 1,709 ESPP 48 94 35 64 Total shares excluded from net loss per share 6,294 2,788 4,694 2,077

Revenues (Tables)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Summary of Disaggregation of Revenue	The following table presents our revenue by channel for the three and nine months ended September 30, 2019 and 2018 : Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands, except percentages) Channel: Desktop $ 15,936 42 % $ 12,481 42 % $ 47,745 44 % $ 40,453 49 % Mobile 21,706 58 17,248 58 60,183 56 42,800 51 Total $ 37,642 100 % $ 29,729 100 % $ 107,928 100 % $ 83,253 100 % The following table presents our revenue disaggregated by geographic location, based on the location of the Company's sellers: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands) (in thousands) United States $ 26,378 $ 19,731 $ 73,654 $ 54,201 International 11,264 9,998 34,274 29,052 Total $ 37,642 $ 29,729 $ 107,928 $ 83,253

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The table below sets forth a summary of financial instruments that are measured at fair value on a recurring basis at September 30, 2019 : Total Quoted Prices in Significant Other Significant (in thousands) Cash equivalents $ 13,447 $ 13,447 $ — $ — The table below sets forth a summary of financial instruments that are measured at fair value on a recurring basis at December 31, 2018 : Total Quoted Prices in Significant Other Significant (in thousands) Cash equivalents $ 13,692 $ 13,692 $ — $ — U.S. Treasury, government and agency debt securities $ 7,524 $ 7,524 $ — $ —

Other Balance Sheet Amounts (Ta

Other Balance Sheet Amounts (Tables)	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Investments in Marketable Securities	Investments in marketable securities as of December 31, 2018 consisted of the following: Amortized Gross Gross Fair (in thousands) Available-for-sale—short-term: U.S. Treasury, government and agency debt securities $ 7,526 $ — $ (2 ) $ 7,524
Schedule of Accounts Payable and Accrued Expenses	Accounts payable and accrued expenses included the following: September 30, 2019 December 31, 2018 (in thousands) Accounts payable—seller $ 195,467 $ 230,423 Accounts payable—trade 5,463 3,122 Accrued employee-related payables 6,103 6,133 Total $ 207,033 $ 239,678

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The Company’s intangible assets as of September 30, 2019 and December 31, 2018 included the following: September 30, 2019 December 31, 2018 (in thousands) Amortizable intangible assets: Developed technology $ 16,878 $ 16,878 Non-compete agreements — 690 Trademarks 20 20 Total identifiable intangible assets, gross 16,898 17,588 Accumulated amortization—intangible assets: Developed technology (9,008 ) (6,888 ) Non-compete agreements — (506 ) Trademarks (20 ) (20 ) Total accumulated amortization—intangible assets (9,028 ) (7,414 ) Total identifiable intangible assets, net $ 7,870 $ 10,174
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The estimated remaining amortization expense associated with the Company's intangible assets was as follows as of September 30, 2019 : Fiscal Year Amount (in thousands) Remaining 2019 $ 706 2020 2,826 2021 2,826 2022 1,512 2023 — Thereafter — Total $ 7,870

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Schedule of Share-based Compensation, Stock Options, Activity	A summary of stock option activity for the nine months ended September 30, 2019 is as follows: Shares Under Option Weighted- Average Exercise Price Weighted- Average Contractual Life Aggregate Intrinsic Value (in thousands) (in thousands) Outstanding at December 31, 2018 3,488 $ 7.06 Granted 1,184 $ 4.98 Exercised (239 ) $ 2.21 Expired (36 ) $ 14.03 Forfeited (73 ) $ 2.62 Outstanding at September 30, 2019 4,324 $ 6.77 7.24 years $ 14,566 Exercisable at September 30, 2019 2,370 $ 8.71 5.94 years $ 5,889
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The Company estimates the fair value of stock options that contain service and/or performance conditions using the Black-Scholes option pricing model. The weighted-average input assumptions used by the Company were as follows: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 Expected term (in years) N/A 5.4 6.1 5.7 Risk-free interest rate N/A 2.75 % 2.51 % 2.53 % Expected volatility N/A 55 % 60 % 57 % Dividend yield N/A — % — % — %
Nonvested Restricted Stock Shares Activity	A summary of RSA activity for the nine months ended September 30, 2019 is as follows: Number of Shares Weighted-Average Grant Date Fair Value (in thousands) Nonvested shares of restricted stock awards outstanding at December 31, 2018 197 $ 12.06 Granted — $ — Canceled (182 ) $ 11.92 Vested (10 ) $ 13.84 Nonvested shares of restricted stock awards outstanding at September 30, 2019 5 $ 13.49
Schedule of Nonvested Restricted Stock Units Activity	A summary of RSU activity for the nine months ended September 30, 2019 is as follows: Number of Shares Weighted-Average Grant Date Fair Value (in thousands) Nonvested restricted stock units outstanding at December 31, 2018 6,100 $ 3.56 Granted 4,856 $ 4.77 Canceled (404 ) $ 3.74 Vested (2,199 ) $ 3.39 Nonvested restricted stock units outstanding at September 30, 2019 8,353 $ 4.30
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs for all Plans	Total stock-based compensation expense recorded in the condensed consolidated statements of operations was as follows: Three Months Ended Nine Months Ended September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 (in thousands) (in thousands) Cost of revenue $ 110 $ 72 $ 308 $ 256 Sales and marketing 1,378 1,187 4,182 3,530 Technology and development 1,157 691 3,382 2,163 General and administrative 2,068 1,910 6,005 6,669 Restructuring and other exit costs — — — 398 Total stock-based compensation expense $ 4,713 $ 3,860 $ 13,877 $ 13,016

Restructuring and Other Exit _2

Restructuring and Other Exit Costs (Tables)	9 Months Ended
	Sep. 30, 2019
Restructuring and Related Activities [Abstract]
Schedule of Restructuring and Other Exit Costs	The following table summarizes restructuring and other exit cost activity for the nine months ended September 30, 2018 (in thousands): Accrued restructuring and other exit costs at January 1, 2018 $ — Restructuring and other exit costs 3,440 Cash paid for restructuring and other exit costs (2,884 ) Non-cash stock-based compensation for restructuring and other exit costs (398 ) Accrued restructuring and other exit costs at September 30, 2018 $ 158

Lease Obligations (Tables)

Lease Obligations (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Schedule of Maturity of Lease Liabilities	The maturity of the Company's lease liabilities were as follows (in thousands): Fiscal Year Remaining 2019 $ 1,932 2020 7,905 2021 4,348 2022 2,284 2023 1,968 Thereafter 8,491 Total lease payments (undiscounted) 26,928 Less: imputed interest (3,440 ) Lease liabilities—total (discounted) $ 23,488

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease liability	$ 23,488
Right-of-use lease asset	$ 22,720
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease liability		$ 15,600
Right-of-use lease asset		$ 14,300

Net Income (Loss) Per Share - B

Net Income (Loss) Per Share - Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic and Diluted EPS:
Net loss	$ (6,174)	$ (8,281)	$ (12,546)	$ (13,792)	$ (17,984)	$ (27,816)	$ (27,001)	$ (59,592)
Weighted-average common shares outstanding	53,029			50,750			52,349	50,482
Weighted-average unvested restricted stock (in shares)	(6)			(237)			(25)	(387)
Weighted-average common shares outstanding used to compute net loss per share	53,023			50,513			52,324	50,095
Basic and diluted net loss per share (usd per share)	$ (0.12)			$ (0.27)			$ (0.52)	$ (1.19)

Net Income (Loss) Per Share - S

Net Income (Loss) Per Share - Shares Excluded From Calculation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	6,294	2,788	4,694	2,077
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	1,078	162	732	72
Unvested restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	0	208	16	232
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	5,168	2,324	3,911	1,709
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	48	94	35	64

Revenues - Narrative (Details)

Revenues - Narrative (Details)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
Payment terms	75 days

Revenues - Revenue Disaggregate

Revenues - Revenue Disaggregated by Sales Distribution Channel (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 37,642	$ 29,729	$ 107,928	$ 83,253
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Desktop
Disaggregation of Revenue [Line Items]
Revenue	$ 15,936	$ 12,481	$ 47,745	$ 40,453
Concentration risk, percentage	42.00%	42.00%	44.00%	49.00%
Mobile
Disaggregation of Revenue [Line Items]
Revenue	$ 21,706	$ 17,248	$ 60,183	$ 42,800
Concentration risk, percentage	58.00%	58.00%	56.00%	51.00%

Revenues - Revenue Disaggrega_2

Revenues - Revenue Disaggregated by Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 37,642	$ 29,729	$ 107,928	$ 83,253
United States
Disaggregation of Revenue [Line Items]
Revenue	26,378	19,731	73,654	54,201
International
Disaggregation of Revenue [Line Items]
Revenue	$ 11,264	$ 9,998	$ 34,274	$ 29,052

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury, government and agency debt securities	$ 0
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	13,447,000	$ 13,692,000
U.S. Treasury, government and agency debt securities		7,524,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	13,447,000	13,692,000
U.S. Treasury, government and agency debt securities		7,524,000
Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
U.S. Treasury, government and agency debt securities		0
Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 0	0
U.S. Treasury, government and agency debt securities		$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - Recurring - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 13,447	$ 13,692
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 13,400	$ 13,700

Other Balance Sheet Amounts - I

Other Balance Sheet Amounts - Investments in Marketable Securities (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 0
U.S. Treasury, government and agency debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		$ 7,526,000
Gross Unrealized Gains		0
Gross Unrealized Losses		(2,000)
Fair Value		$ 7,524,000

Other Balance Sheet Amounts - N

Other Balance Sheet Amounts - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Available-for-sale securities	$ 0	$ 0
Realized gains (losses)	0	0	$ 0
Unrealized holding gains (losses) reclassified	0	0	0
Sale of available-for-sale investments		0	$ 9,228,000
Restricted cash	$ 0	$ 0		$ 0

Other Balance Sheet Amounts - A

Other Balance Sheet Amounts - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts payable—seller	$ 195,467	$ 230,423
Accounts payable—trade	5,463	3,122
Accrued employee-related payables	6,103	6,133
Total	$ 207,033	$ 239,678

Intangible Assets - Finite-Live

Intangible Assets - Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	$ 16,898	$ 17,588
Total accumulated amortization—intangible assets	(9,028)	(7,414)
Total	7,870	10,174
Developed technology
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	16,878	16,878
Total accumulated amortization—intangible assets	(9,008)	(6,888)
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	0	690
Total accumulated amortization—intangible assets	0	(506)
Trademarks
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	20	20
Total accumulated amortization—intangible assets	$ (20)	$ (20)

Intangible Assets - Narrative (

Intangible Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense of intangible assets	$ 0.7	$ 0.8	$ 2.3	$ 2.4

Intangible Assets - Finite-Li_2

Intangible Assets - Finite-Lived Intangible Assets, Future Amortization Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fiscal Year
Remaining 2019	$ 706
2020	2,826
2021	2,826
2022	1,512
2023	0
Thereafter	0
Total	$ 7,870	$ 10,174

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details)	9 Months Ended
	Sep. 30, 2019shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant	4,377,171
Two Year RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Award vesting rights, percentage	50.00%
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Stock Option | Vesting After One Year of Service
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Award vesting rights, percentage	25.00%
RSAs and RSUs | Vesting After One Year of Service
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Award vesting rights, percentage	25.00%

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options Outstanding (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares
Shares Under Option
Beginning balance (in shares) | shares	3,488
Granted (in shares) | shares	1,184
Exercised (in shares) | shares	(239)
Expired (in shares) | shares	(36)
Forfeited (in shares) | shares	(73)
Ending balance (in shares) | shares	4,324
Exercisable (in shares) | shares	2,370
Weighted- Average Exercise Price
Beginning balance (usd per share) | $ / shares	$ 7.06
Granted (usd per share) | $ / shares	4.98
Exercised (usd per share) | $ / shares	2.21
Expired (usd per share) | $ / shares	14.03
Forfeited (usd per share) | $ / shares	2.62
Ending balance (usd per share) | $ / shares	6.77
Exercisable (usd per share) | $ / shares	$ 8.71
Weighted- Average Contractual Life
Outstanding	7 years 2 months 26 days
Exercisable	5 years 11 months 8 days
Aggregate Intrinsic Value
Outstanding | $	$ 14,566
Exercisable | $	$ 5,889

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Options Narrative (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)$ / shares
Number of Shares
Intrinsic values of options exercised	$ 1.3
Unrecognized employee stock-based compensation	$ 4.6
Weighted average grant date fair value (usd per share) | $ / shares	$ 2.85
Fair value of options vested in period	$ 1.3
Stock Option
Number of Shares
Unrecognized employee stock-based compensation, period for recognition	2 years 9 months

Stock-Based Compensation - Valu

Stock-Based Compensation - Valuation Assumptions (Details) - Stock Option	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 4 months 24 days	6 years 1 month 6 days	5 years 8 months 12 days
Risk-free interest rate	2.75%	2.51%	2.53%
Expected volatility	55.00%	60.00%	57.00%
Dividend yield	0.00%	0.00%	0.00%

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Activity (Details) - Restricted Stock Awards shares in Thousands	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Number of Shares
Beginning balance (in shares) | shares	197
Granted (in shares) | shares	0
Canceled (in shares) | shares	(182)
Vested (in shares) | shares	(10)
Ending balance (in shares) | shares	5
Weighted-Average Grant Date Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 12.06
Granted (in dollars per share) | $ / shares	0
Canceled (in dollars per share) | $ / shares	11.92
Vested (in dollars per share) | $ / shares	13.84
Ending balance (in dollars per share) | $ / shares	$ 13.49

Stock-Based Compensation - Re_2

Stock-Based Compensation - Restricted Stock Narrative (Details) - Unvested restricted stock awards	9 Months Ended
	Sep. 30, 2019USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of restricted stock vested	$ 100,000
Unrecognized employee stock-based compensation	$ 37,900
Unrecognized employee stock-based compensation, period for recognition	7 months 6 days

Stock-Based Compensation - Re_3

Stock-Based Compensation - Restricted Stock Units Activity (Details) - Restricted Stock Units (RSUs) shares in Thousands	9 Months Ended
	Sep. 30, 2019$ / sharesshares
Number of Shares
Beginning balance (in shares) | shares	6,100
Granted (in shares) | shares	4,856
Canceled (in shares) | shares	(404)
Vested (in shares) | shares	(2,199)
Ending balance (in shares) | shares	8,353
Weighted-Average Grant Date Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 3.56
Granted (in dollars per share) | $ / shares	4.77
Canceled (in dollars per share) | $ / shares	3.74
Vested (in dollars per share) | $ / shares	3.39
Ending balance (in dollars per share) | $ / shares	$ 4.30

Stock-Based Compensation - Re_4

Stock-Based Compensation - Restricted Stock Units Narrative (Details) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share) | $ / shares	$ 4.77
Fair value of restricted stock vested	$ 11.3
Intrinsic value of nonvested unit	72.8
Unrecognized employee stock-based compensation	$ 26.5
Unrecognized employee stock-based compensation, weighted average period	2 years 3 months 18 days
Two Year RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units included units granted (in shares) | shares	1.6
Award vesting rights, percentage	50.00%
Vesting period	2 years

Stock-Based Compensation - Empl

Stock-Based Compensation - Employee Stock Purchase Plan Narrative (Details) - shares	1 Months Ended	9 Months Ended
	Nov. 30, 2013	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved		4,377,171
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual percentage increase		1.00%
2014 Employee Stock Purchase Plan | Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Offering Period	6 months
Maximum employee subscription rate	10.00%
Purchase price of common stock, percent	85.00%
Number of shares reserved		2,001,256

Stock-Based Compensation - St_3

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 4,713	$ 3,860	$ 13,877	$ 13,016
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	110	72	308	256
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,378	1,187	4,182	3,530
Technology and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,157	691	3,382	2,163
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	2,068	1,910	6,005	6,669
Restructuring and other exit costs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 0	$ 0	$ 0	$ 398

Restructuring and Other Exit _3

Restructuring and Other Exit Costs - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Restructuring and other exit costs	$ 0	$ 0	$ 0	$ 3,440,000
Accrued restructuring and other exit costs		$ 158,000		$ 158,000	$ 100,000	$ 0

Restructuring and Other Exit _4

Restructuring and Other Exit Costs - Schedule of Restructuring and Other Exit Costs (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring Reserve [Roll Forward]
Accrued restructuring and other exit costs at January 1, 2018			$ 100,000	$ 0
Restructuring and other exit costs	$ 0	$ 0	$ 0	3,440,000
Cash paid for restructuring and other exit costs				(2,884,000)
Non-cash stock-based compensation for restructuring and other exit costs				(398,000)
Accrued restructuring and other exit costs at September 30, 2018		$ 158,000		$ 158,000

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Provision (benefit) for income taxes	$ 55	$ 84	$ (569)	$ 233

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Financial Standby Letter of Credit
Other Commitments [Line Items]
Letters of credit outstanding, amount	$ 2.5	$ 2.9

Lease Obligations - Narrative (

Lease Obligations - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Lessee, Lease, Description [Line Items]
Extension option	1 year		1 year
Weighted average remaining lease term	6 years 3 months 10 days		6 years 3 months 10 days
Weighted average discount rate, percent	4.73%		4.73%
Lease expense	$ 2,000,000		$ 5,700,000
Short-term lease expense	100,000		500,000
Rental expense under ASC 840		$ 3,200,000		$ 9,700,000
Sublease income under ASC 842	48,400		200,000
Sublease income, under ASC 840		$ 200,000		$ 600,000
Lease not yet commenced, expected lease liability	$ 400,000		$ 400,000
Minimum
Lessee, Lease, Description [Line Items]
Lease terms	1 year		1 year
Maximum
Lessee, Lease, Description [Line Items]
Lease terms	10 years		10 years

Lease Obligations - Schedule of

Lease Obligations - Schedule of Lease Liability Maturities (Details) $ in Thousands	Sep. 30, 2019USD ($)
Fiscal Year
Remaining 2019	$ 1,932
2020	7,905
2021	4,348
2022	2,284
2023	1,968
Thereafter	8,491
Total lease payments (undiscounted)	26,928
Less: imputed interest	(3,440)
Lease liabilities—total (discounted)	$ 23,488

Debt (Details)

Debt (Details)	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)
Debt Instrument [Line Items]
Adjusted Quick Ratio	1.15
Revolving Credit Facility | Loan Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 40,000,000
Capitalized debt issuance costs		$ 100,000
Unused capacity fee, percentage	0.15%
Adjusted Quick Ratio, in streamline period	1.05
Revolving Credit Facility | Loan Agreement | Covenant Compliance Period One
Debt Instrument [Line Items]
Adjusted EBITDA threshold	0.20
Revolving Credit Facility | Loan Agreement | Covenant Compliance Period Two
Debt Instrument [Line Items]
Adjusted EBITDA minimum	$ 1
Revolving Credit Facility | Loan Agreement | Covenant Compliance Period Three
Debt Instrument [Line Items]
Adjusted EBITDA minimum	$ 5,000,000
Revolving Credit Facility | Loan Agreement | Streamline Period Applies | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate	2.50%
Revolving Credit Facility | Loan Agreement | Streamline Period Applies | Prime Rate
Debt Instrument [Line Items]
Variable interest rate	0.50%
Revolving Credit Facility | Loan Agreement | Streamline Period Does Not Apply | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate	4.00%
Revolving Credit Facility | Loan Agreement | Streamline Period Does Not Apply | Prime Rate
Debt Instrument [Line Items]
Variable interest rate	2.00%
Revolving Credit Facility | Loan Agreement | Covenant Term, Scenario One
Debt Instrument [Line Items]
Adjusted Quick Ratio	1
Adjusted EBITDA maximum	$ 0
Revolving Credit Facility | Loan Agreement | Covenant Term, Scenario Two
Debt Instrument [Line Items]
Adjusted Quick Ratio	0.90
Adjusted EBITDA minimum	$ 0

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Events - RTK $ in Millions	Oct. 21, 2019USD ($)solution
Subsequent Event [Line Items]
Business acquisition, cash consideration | $	$ 11
Number of solutions to extend | solution	2