0001595974-19-000114 | 10-Q | XBRL Viewer

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Cover Page - shares	6 Months Ended
Cover Page - shares	Jun. 30, 2019	Jul. 24, 2019
Cover page.
Title of 12(b) Security	Common stock, par value $0.00001 per share
Entity Incorporation, State or Country Code	DE
Entity Registrant Name	RUBICON PROJECT, INC.
Entity Central Index Key	0001595974
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-36384
Document Period End Date	Jun. 30, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		52,990,930
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
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
Trading Symbol	RUBI
Security Exchange Name	NYSE
Entity Interactive Data Current	Yes
Entity Ex Transition Period	true

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 86,111	$ 80,452
Marketable securities	0	7,524
Accounts receivable, net	178,025	205,683
Prepaid expenses and other current assets	5,901	6,882
TOTAL CURRENT ASSETS	270,037	300,541
Property and equipment, net	24,340	33,487
Right-of-use lease asset	14,497
Internal use software development costs, net	15,257	14,570
Intangible assets, net	8,589	10,174
Other assets, non-current	2,117	1,240
TOTAL ASSETS	334,837	360,012
Current liabilities:
Accounts payable and accrued expenses	213,157	239,678
Lease liabilities, current	6,826
Other current liabilities	531	1,304
TOTAL CURRENT LIABILITIES	220,514	240,982
Lease liabilities, non-current	8,516
Other liabilities, non-current	179	1,017
TOTAL LIABILITIES	229,209	241,999
Commitments and contingencies (Note 10)
STOCKHOLDERS' EQUITY
Preferred stock, $0.00001 par value, 10,000 shares authorized at June 30, 2019 and December 31, 2018; 0 shares issued and outstanding at June 30, 2019 and December 31, 2018	0	0
Common stock, $0.00001 par value; 500,000 shares authorized at June 30, 2019 and December 31, 2018; 52,984 and 51,159 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	1	1
Additional paid-in capital	442,353	433,877
Accumulated other comprehensive loss	(293)	(259)
Accumulated deficit	(336,433)	(315,606)
TOTAL STOCKHOLDERS' EQUITY	105,628	118,013
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 334,837	$ 360,012

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 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	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (usd per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares, issued	52,984,000	51,159,000
Common stock, shares, outstanding	52,984,000	51,159,000

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenue	$ 37,870,000	$ 28,648,000	$ 70,286,000	$ 53,524,000
Expenses:
Cost of revenue	15,085,000	15,044,000	30,201,000	29,827,000
Sales and marketing	11,519,000	11,135,000	22,111,000	23,392,000
Technology and development	9,839,000	9,245,000	19,555,000	19,739,000
General and administrative	10,027,000	11,441,000	20,307,000	23,985,000
Restructuring and other exit costs	0	974,000	0	3,440,000
Total expenses	46,470,000	47,839,000	92,174,000	100,383,000
Loss from operations	(8,600,000)	(19,191,000)	(21,888,000)	(46,859,000)
Other (income) expense:
Interest income, net	(214,000)	(274,000)	(407,000)	(545,000)
Other income	(46,000)	(210,000)	(188,000)	(420,000)
Foreign exchange (gain) loss, net	(143,000)	(797,000)	158,000	(243,000)
Total other income, net	(403,000)	(1,281,000)	(437,000)	(1,208,000)
Loss before income taxes	(8,197,000)	(17,910,000)	(21,451,000)	(45,651,000)
Provision (benefit) for income taxes	84,000	74,000	(624,000)	149,000
Net loss	$ (8,281,000)	$ (17,984,000)	$ (20,827,000)	$ (45,800,000)
Net loss per share:
Basic and Diluted (usd per share)	$ (0.16)	$ (0.36)	$ (0.40)	$ (0.92)
Weighted average shares used to compute net loss per share:
Basic and Diluted (in shares)	52,358	50,071	51,969	49,883

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (8,281)	$ (17,984)	$ (20,827)	$ (45,800)
Other comprehensive income (loss):
Unrealized gain on investments	0	16	2	6
Foreign currency translation adjustments	(128)	(338)	(36)	(124)
Other comprehensive loss	(128)	(322)	(34)	(118)
Comprehensive loss	$ (8,409)	$ (18,306)	$ (20,861)	$ (45,918)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance (in shares) at Dec. 31, 2017		50,239,000
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)		9,000
Exercise of common stock options	6		6
Issuance of common stock related to RSU vesting (in shares)		51,000
Issuance of common stock related to RSU vesting	0	$ 0
Shares withheld related to net share settlement (in shares)		(19,000)
Shares withheld related to net share settlement	(40)		(40)
Stock-based compensation	4,689		4,689
Other comprehensive income	204			204
Net loss	(27,816)				(27,816)
Ending Balance (in shares) at Mar. 31, 2018		50,280,000
Ending Balance at Mar. 31, 2018	141,654	$ 0	423,009	245	(281,600)
Beginning Balance (in shares) at Dec. 31, 2017		50,239,000
Beginning Balance at Dec. 31, 2017	164,611	$ 0	418,354	41	(253,784)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income	(118)
Net loss	(45,800)
Ending Balance (in shares) at Jun. 30, 2018		50,750,000
Ending Balance at Jun. 30, 2018	127,664	$ 1	427,324	(77)	(299,584)
Beginning Balance (in shares) at Mar. 31, 2018		50,280,000
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)		40,000
Exercise of common stock options	39		39
Restricted stock awards, net (in shares)		(156,000)
Restricted stock awards, net	0
Issuance of common stock related to RSU vesting (in shares)		779,000
Issuance of common stock related to RSU vesting	1	$ 1
Shares withheld related to net share settlement (in shares)		(282,000)
Shares withheld related to net share settlement	(618)		(618)
Issuance of common stock related to employee stock purchase plan (in shares)		89,000
Issuance of common stock related to employee stock purchase plan	143		143
Stock-based compensation	4,751		4,751
Other comprehensive income	(322)			(322)
Net loss	(17,984)				(17,984)
Ending Balance (in shares) at Jun. 30, 2018		50,750,000
Ending Balance at Jun. 30, 2018	$ 127,664	$ 1	427,324	(77)	(299,584)
Beginning Balance (in shares) at Dec. 31, 2018	51,159,000	51,159,000
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)		76,000
Exercise of common stock options	251		251
Restricted stock awards, net (in shares)		(182,000)
Restricted stock awards, net	0	$ 0
Issuance of common stock related to RSU vesting (in shares)		1,171,000
Issuance of common stock related to RSU vesting	0	$ 0
Shares withheld related to net share settlement (in shares)		(459,000)
Shares withheld related to net share settlement	(1,835)		(1,835)
Stock-based compensation	4,514		4,514
Other comprehensive income	94			94
Net loss	(12,546)				(12,546)
Ending Balance (in shares) at Mar. 31, 2019		51,765,000
Ending Balance at Mar. 31, 2019	$ 108,491	$ 1	436,807	(165)	(328,152)
Beginning Balance (in shares) at Dec. 31, 2018	51,159,000	51,159,000
Beginning Balance at Dec. 31, 2018	$ 118,013	$ 1	433,877	(259)	(315,606)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income	(34)
Net loss	$ (20,827)
Ending Balance (in shares) at Jun. 30, 2019	52,984,000	52,984,000
Ending Balance at Jun. 30, 2019	$ 105,628	$ 1	442,353	(293)	(336,433)
Beginning Balance (in shares) at Mar. 31, 2019		51,765,000
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)		79,000
Exercise of common stock options	132		132
Issuance of common stock related to RSU vesting (in shares)		1,022,000
Issuance of common stock related to RSU vesting	0	$ 0
Shares withheld related to net share settlement (in shares)		0
Shares withheld related to net share settlement	(12)		(12)
Issuance of common stock related to employee stock purchase plan (in shares)		118,000
Issuance of common stock related to employee stock purchase plan	477		477
Stock-based compensation	4,949		4,949
Other comprehensive income	(128)			(128)
Net loss	$ (8,281)				(8,281)
Ending Balance (in shares) at Jun. 30, 2019	52,984,000	52,984,000
Ending Balance at Jun. 30, 2019	$ 105,628	$ 1	$ 442,353	$ (293)	$ (336,433)

Condensed Consolidated Statement of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
OPERATING ACTIVITIES:
Net loss	$ (20,827)	$ (45,800)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	16,814	17,588
Stock-based compensation	9,164	9,156
Loss on disposal of property and equipment	16	120
Provision for doubtful accounts	966	215
Accretion of available-for-sale securities	24	(318)
Non-cash lease expense	(379)
Unrealized foreign currency (gains) losses, net	777	(766)
Deferred income taxes	(752)	0
Changes in operating assets and liabilities:
Accounts receivable	26,831	12,342
Prepaid expenses and other assets	593	2,351
Accounts payable and accrued expenses	(27,567)	(15,287)
Other liabilities	(127)	(691)
Net cash provided by (used in) operating activities	5,533	(21,090)
INVESTING ACTIVITIES:
Purchases of property and equipment	(2,212)	(1,216)
Capitalized internal use software development costs	(4,160)	(4,817)
Investments in available-for-sale securities	0	(23,991)
Maturities of available-for-sale securities	7,500	41,150
Sales of available-for-sale securities	0	6,086
Net cash provided by investing activities	1,128	17,212
FINANCING ACTIVITIES:
Proceeds from exercise of stock options	383	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	(987)	(470)
EFFECT OF EXCHANGE RATE CHANGES ON CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(15)	(47)
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	5,659	(4,395)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period	80,452	76,642
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — End of period	86,111	72,247
SUPPLEMENTAL DISCLOSURES OF OTHER CASH FLOW INFORMATION:
Cash paid for income taxes	145	167
Cash paid for interest	25	30
Capitalized assets financed by accounts payable and accrued expenses	118	712
Capitalized stock-based compensation	299	$ 284
Operating lease right-of-use assets obtained in exchange for new operating lease liabilities	$ 3,237

Organization and Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2019

Accounting Policies [Abstract]

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 six months ended June 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 June 30, 2019 and for the three and six months ended June 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. 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 ("ASU 2019-01"), which clarifies certain topics around lease guidance. One of the provisions of ASU 2019-01 pertains to the Company as it updates existing guidance by explicitly allowing an exception to transition disclosures typically required, while adopting ASC 842. Under this guidance, entities that have adopted ASC 842 are not required to provide identical disclosures for the comparative previous year period in the year of adoption. ASU 2019-01 is required to be adopted concurrently with the adoption of ASC 842, and as such, the Company adopted ASU 2019-01 during the first quarter of 2019.

Net Income (Loss) Per Share

6 Months Ended

Jun. 30, 2019

Earnings Per Share [Abstract]

Net Income (Loss) Per Share

The following table presents the basic and diluted net loss per share:



	Three Months Ended						Six Months Ended
	June 30, 2019			June 30, 2018			June 30, 2019			June 30, 2018
	(in thousands, except per share data)
Basic and Diluted EPS:
Net loss	$	(8,281	)	$	(17,984	)	$	(20,827	)	$	(45,800	)
Weighted-average common shares outstanding	52,369			50,443			52,004			50,346
Weighted-average unvested restricted stock	(11		)	(372		)	(35		)	(463		)
Weighted-average common shares outstanding used to compute net loss per share	52,358			50,071			51,969			49,883
Basic and diluted net loss per share	$	(0.16	)	$	(0.36	)	$	(0.40	)	$	(0.92	)

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		Six Months Ended
	June 30, 2019	June 30, 2018	June 30, 2019	June 30, 2018
	(in thousands)		(in thousands)
Options to purchase common stock	605	18	559	27
Unvested restricted stock awards	5	301	24	244
Unvested restricted stock units	3,818	1,434	3,282	1,401
ESPP	28	36	28	49
Total shares excluded from net loss per share	4,456	1,789	3,893	1,721

Revenues

6 Months Ended

Jun. 30, 2019

Revenue from Contract with Customer [Abstract]

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 six months ended June 30, 2019 and 2018:



	Three Months Ended								Six Months Ended
	June 30, 2019				June 30, 2018				June 30, 2019				June 30, 2018
	(in thousands, except percentages)
Channel:
Desktop	$	16,588	44	%	$	13,663	48	%	$	31,809	45	%	$	27,972	52	%
Mobile	21,282		56		14,985		52		38,477		55		25,552		48
Total	$	37,870	100	%	$	28,648	100	%	$	70,286	100	%	$	53,524	100	%

The following table presents our revenue disaggregated by geographic location, based on the location of the Company's sellers:



	Three Months Ended				Six Months Ended
	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
	(in thousands)				(in thousands)
United States	$	25,790	$	18,966	$	47,276	$	34,470
International	12,080		9,682		23,010		19,054
Total	$	37,870	$	28,648	$	70,286	$	53,524

Fair Value Measurements

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

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 June 30, 2019:



	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents	$	13,377	$	13,377	$	—	$	—

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 Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents	$	13,692	$	13,692	$	—	$	—
U.S. Treasury, government and agency debt securities	$	7,524	$	7,524	$	—	$	—

At June 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.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Other Balance Sheet Amounts

6 Months Ended

Jun. 30, 2019

Balance Sheet Related Disclosures [Abstract]

Other Balance Sheet Amounts

Investments in marketable securities as of December 31, 2018 consisted of the following:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(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 June 30, 2019. For the three and six months ended June 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 three and six months ended June 30, 2018, the Company sold $6.1 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:



	June 30, 2019		December 31, 2018
	(in thousands)
Accounts payable—seller	$	202,463	$	230,423
Accounts payable—trade	4,849		3,122
Accrued employee-related payables	5,845		6,133
Total	$	213,157	$	239,678

There was no restricted cash as of June 30, 2019 and December 31, 2018.

Intangible Assets

6 Months Ended

Jun. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

The Company’s intangible assets as of June 30, 2019 and December 31, 2018 included the following:



	June 30, 2019			December 31, 2018
	(in thousands)
Amortizable intangible assets:
Developed technology	$	16,878		$	16,878
Non-compete agreements	690			690
Trademarks	20			20
Total identifiable intangible assets, gross	17,588			17,588
Accumulated amortization—intangible assets:
Developed technology	(8,301		)	(6,888		)
Non-compete agreements	(678		)	(506		)
Trademarks	(20		)	(20		)
Total accumulated amortization—intangible assets	(8,999		)	(7,414		)
Total identifiable intangible assets, net	$	8,589		$	10,174

Amortization of intangible assets for the three months ended June 30, 2019 and 2018 was $0.8 million for both periods, and $1.6 million for both the six months ended June 30, 2019 and 2018. The estimated remaining amortization expense associated with the Company's intangible assets was as follows as of June 30, 2019:



Fiscal Year	Amount
	(in thousands)
Remaining 2019	$	1,425
2020	2,826
2021	2,826
2022	1,512
2023	—
Thereafter	—
Total	$	8,589

Stock-Based Compensation

6 Months Ended

Jun. 30, 2019

Share-based Payment Arrangement [Abstract]

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 4,444,960 shares remained available for future grants at June 30, 2019 under the plans.

Stock Options

A summary of stock option activity for the six months ended June 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	(156	)	$	2.46
Expired	(35	)	$	14.13
Forfeited	(73	)	$	2.62
Outstanding at June 30, 2019	4,408		$	6.68	7.45 years	$	6,829
Exercisable at June 30, 2019	2,340		$	8.69	6.07 years	$	2,720

The total intrinsic values of options exercised during the six months ended June 30, 2019 was $0.6 million. At June 30, 2019, the Company had unrecognized employee stock-based compensation expense relating to nonvested stock options of approximately $5.2 million, which is expected to be recognized over a weighted-average period of 2.9 years. The weighted-average grant date fair value per share of stock options granted during the six months ended June 30, 2019 was $2.85. Total fair value of options vested during the six months ended June 30, 2019 was $1.0 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		Six Months Ended
	June 30, 2019	June 30, 2018	June 30, 2019		June 30, 2018
Expected term (in years)	N/A	N/A	6.1		6.1
Risk-free interest rate	N/A	N/A	2.51	%	2.66	%
Expected volatility	N/A	N/A	60	%	57	%
Dividend yield	N/A	N/A	—	%	—	%

Restricted Stock Awards

A summary of RSA activity for the six months ended June 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 June 30, 2019	5		$	13.49

The aggregate fair value of restricted stock with service conditions that vested during the six months ended June 30, 2019 was $0.1 million. At June 30, 2019, the Company had unrecognized stock-based compensation expense for RSAs with service conditions of $0.1 million, which is expected to be recognized over a weighted-average period of 0.9 years.

Restricted Stock Units

A summary of RSU activity for the six months ended June 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	4,668		$	4.68
Canceled	(288	)	$	3.58
Vested	(2,193	)	$	3.39
Nonvested restricted stock units outstanding at June 30, 2019	8,287		$	4.24

The weighted-average grant date fair value per share of RSUs granted during the six months ended June 30, 2019 was $4.68, which included 1.6 million RSUs that vest 50% annually over two years. The aggregate fair value of RSUs that vested during six months ended June 30, 2019 was $11.2 million. At June 30, 2019, the intrinsic value of nonvested RSUs was $52.7 million. At June 30, 2019, the Company had unrecognized stock-based compensation expense relating to nonvested RSUs of approximately $29.8 million, which is expected to be recognized over a weighted-average period of 2.5 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 June 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				Six Months Ended
	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
	(in thousands)				(in thousands)
Cost of revenue	$	106	$	77	$	198	$	184
Sales and marketing	1,459		1,158		2,804		2,343
Technology and development	1,166		623		2,225		1,472
General and administrative	2,064		2,402		3,937		4,759
Restructuring and other exit costs	—		352		—		398
Total stock-based compensation expense	$	4,795	$	4,612	$	9,164	$	9,156

Restructuring and Other Exit Costs

6 Months Ended

Jun. 30, 2019

Restructuring and Related Activities [Abstract]

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 $1.0 million and $3.4 million were incurred during the three and six months ended June 30, 2018, respectively, related to severance and one-time termination benefit costs.

The following table summarizes restructuring and other exit cost activity for the six months ended June 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	(2,561		)
Non-cash stock-based compensation for restructuring and other exit costs	(398		)
Accrued restructuring and other exit costs at June 30, 2018	$	481

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 six months ended June 30, 2019, and all remaining accrued costs associated with the 2018 restructuring events were paid in the first quarter of 2019.

Income Taxes	6 Months Ended
Income Taxes	Jun. 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 six months ended June 30, 2019, respectively, and income tax expenses of $0.1 million for both the three and six months ended June 30, 2018. The tax provision for the three and six months ended June 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 six months ended June 30, 2019, and the Company does not expect to have any significant changes to unrecognized tax benefits through the end of the fiscal year. Because of the Company's history of tax losses, all years remain open to tax audit.

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments As of June 30, 2019 and December 31, 2018, the Company had $3.7 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 June 30, 2019. However, based on management’s knowledge as of June 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 The Company has entered into severance agreements with certain employees and officers. The Company may be required to pay severance and accelerate the vesting of certain equity awards in the event of involuntary terminations.

Lease Obligations

6 Months Ended

Jun. 30, 2019

Leases [Abstract]

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 seven years, and the weighted average remaining lease term of leases included in the lease liability is 3.1 years as of June 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 June 30, 2019, a weighted average discount rate of 5.20% 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 six months ended June 30, 2019, the Company recognized $1.8 million and $3.6 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 six months ended June 30, 2019, the Company recognized $0.2 million and $0.4 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 six months ended June 30, 2018, the Company recognized rental expenses of $3.3 million and $6.5 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 $46.2 thousand and $0.2 million for real estate leases for which it subleases the property to a third party during the three months ended June 30, 2019 and 2018, respectively, and $0.2 million and $0.4 million for the six months ended June 30, 2019 and 2018, respectively.

The maturity of the Company's lease liabilities were as follows (in thousands):



Fiscal Year
Remaining 2019	$	3,808
2020	6,795
2021	3,043
2022	1,096
2023	809
Thereafter	1,046
Total lease payments (undiscounted)	16,597
Less: imputed interest	(1,255		)
Lease liabilities—total (discounted)	$	15,342

In addition to the leases included in these condensed consolidated financial statements, the Company entered into lease agreements for office locations in New York and New Jersey during the first half of 2019 that have not yet commenced as of June 30, 2019. The Company anticipates the recognition of approximately $9 million additional lease liabilities related to the New York and New Jersey leases when the properties are made available to the Company for use, which is expected to occur in the third quarter of 2019.

Debt	6 Months Ended
Debt	Jun. 30, 2019
Debt Disclosure [Abstract]
Debt	Debt In September 2018, the Company amended and restated its loan and security agreement with Silicon Valley Bank (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 June 30, 2019, the Company's Adjusted Quick Ratio was 1.16, 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 June 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 June 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.

Organization and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 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 six months ended June 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 June 30, 2019 and for the three and six months ended June 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	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. 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 ("ASU 2019-01"), which clarifies certain topics around lease guidance. One of the provisions of ASU 2019-01 pertains to the Company as it updates existing guidance by explicitly allowing an exception to transition disclosures typically required, while adopting ASC 842. Under this guidance, entities that have adopted ASC 842 are not required to provide identical disclosures for the comparative previous year period in the year of adoption. ASU 2019-01 is required to be adopted concurrently with the adoption of ASC 842, and as such, the Company adopted ASU 2019-01 during the first quarter of 2019.

Net Income (Loss) Per Share (Tables)

6 Months Ended

Jun. 30, 2019

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The following table presents the basic and diluted net loss per share:



	Three Months Ended						Six Months Ended
	June 30, 2019			June 30, 2018			June 30, 2019			June 30, 2018
	(in thousands, except per share data)
Basic and Diluted EPS:
Net loss	$	(8,281	)	$	(17,984	)	$	(20,827	)	$	(45,800	)
Weighted-average common shares outstanding	52,369			50,443			52,004			50,346
Weighted-average unvested restricted stock	(11		)	(372		)	(35		)	(463		)
Weighted-average common shares outstanding used to compute net loss per share	52,358			50,071			51,969			49,883
Basic and diluted net loss per share	$	(0.16	)	$	(0.36	)	$	(0.40	)	$	(0.92	)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share



	Three Months Ended		Six Months Ended
	June 30, 2019	June 30, 2018	June 30, 2019	June 30, 2018
	(in thousands)		(in thousands)
Options to purchase common stock	605	18	559	27
Unvested restricted stock awards	5	301	24	244
Unvested restricted stock units	3,818	1,434	3,282	1,401
ESPP	28	36	28	49
Total shares excluded from net loss per share	4,456	1,789	3,893	1,721

Revenues (Tables)

6 Months Ended

Jun. 30, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table presents our revenue by channel for the three and six months ended June 30, 2019 and 2018:



	Three Months Ended								Six Months Ended
	June 30, 2019				June 30, 2018				June 30, 2019				June 30, 2018
	(in thousands, except percentages)
Channel:
Desktop	$	16,588	44	%	$	13,663	48	%	$	31,809	45	%	$	27,972	52	%
Mobile	21,282		56		14,985		52		38,477		55		25,552		48
Total	$	37,870	100	%	$	28,648	100	%	$	70,286	100	%	$	53,524	100	%

The following table presents our revenue disaggregated by geographic location, based on the location of the Company's sellers:



	Three Months Ended				Six Months Ended
	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
	(in thousands)				(in thousands)
United States	$	25,790	$	18,966	$	47,276	$	34,470
International	12,080		9,682		23,010		19,054
Total	$	37,870	$	28,648	$	70,286	$	53,524

Fair Value Measurements (Tables)

6 Months Ended

Jun. 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 June 30, 2019:



	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents	$	13,377	$	13,377	$	—	$	—

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 Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(in thousands)
Cash equivalents	$	13,692	$	13,692	$	—	$	—
U.S. Treasury, government and agency debt securities	$	7,524	$	7,524	$	—	$	—

Other Balance Sheet Amounts (Tables)

6 Months Ended

Jun. 30, 2019

Balance Sheet Related Disclosures [Abstract]

Investments in Marketable Securities

Investments in marketable securities as of December 31, 2018 consisted of the following:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(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 Liabilities

Accounts payable and accrued expenses included the following:



	June 30, 2019		December 31, 2018
	(in thousands)
Accounts payable—seller	$	202,463	$	230,423
Accounts payable—trade	4,849		3,122
Accrued employee-related payables	5,845		6,133
Total	$	213,157	$	239,678

Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Finite-Lived Intangible Assets

The Company’s intangible assets as of June 30, 2019 and December 31, 2018 included the following:



	June 30, 2019			December 31, 2018
	(in thousands)
Amortizable intangible assets:
Developed technology	$	16,878		$	16,878
Non-compete agreements	690			690
Trademarks	20			20
Total identifiable intangible assets, gross	17,588			17,588
Accumulated amortization—intangible assets:
Developed technology	(8,301		)	(6,888		)
Non-compete agreements	(678		)	(506		)
Trademarks	(20		)	(20		)
Total accumulated amortization—intangible assets	(8,999		)	(7,414		)
Total identifiable intangible assets, net	$	8,589		$	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 June 30, 2019:



Fiscal Year	Amount
	(in thousands)
Remaining 2019	$	1,425
2020	2,826
2021	2,826
2022	1,512
2023	—
Thereafter	—
Total	$	8,589

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Share-based Payment Arrangement [Abstract]

Schedule of Share-based Compensation, Stock Options, Activity

A summary of stock option activity for the six months ended June 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	(156	)	$	2.46
Expired	(35	)	$	14.13
Forfeited	(73	)	$	2.62
Outstanding at June 30, 2019	4,408		$	6.68	7.45 years	$	6,829
Exercisable at June 30, 2019	2,340		$	8.69	6.07 years	$	2,720

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions



	Three Months Ended		Six Months Ended
	June 30, 2019	June 30, 2018	June 30, 2019		June 30, 2018
Expected term (in years)	N/A	N/A	6.1		6.1
Risk-free interest rate	N/A	N/A	2.51	%	2.66	%
Expected volatility	N/A	N/A	60	%	57	%
Dividend yield	N/A	N/A	—	%	—	%

Nonvested Restricted Stock Shares Activity

A summary of RSA activity for the six months ended June 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 June 30, 2019	5		$	13.49

Schedule of Nonvested Restricted Stock Units Activity

A summary of RSU activity for the six months ended June 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	4,668		$	4.68
Canceled	(288	)	$	3.58
Vested	(2,193	)	$	3.39
Nonvested restricted stock units outstanding at June 30, 2019	8,287		$	4.24

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				Six Months Ended
	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
	(in thousands)				(in thousands)
Cost of revenue	$	106	$	77	$	198	$	184
Sales and marketing	1,459		1,158		2,804		2,343
Technology and development	1,166		623		2,225		1,472
General and administrative	2,064		2,402		3,937		4,759
Restructuring and other exit costs	—		352		—		398
Total stock-based compensation expense	$	4,795	$	4,612	$	9,164	$	9,156

Restructuring and Other Exit Costs (Tables)

6 Months Ended

Jun. 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 six months ended June 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	(2,561		)
Non-cash stock-based compensation for restructuring and other exit costs	(398		)
Accrued restructuring and other exit costs at June 30, 2018	$	481

Lease Obligations (Tables)

6 Months Ended

Jun. 30, 2019

Leases [Abstract]

Schedule of Lease Liability Maturity

The maturity of the Company's lease liabilities were as follows (in thousands):



Fiscal Year
Remaining 2019	$	3,808
2020	6,795
2021	3,043
2022	1,096
2023	809
Thereafter	1,046
Total lease payments (undiscounted)	16,597
Less: imputed interest	(1,255		)
Lease liabilities—total (discounted)	$	15,342

Organization and Summary of Significant Accounting Policies Adoption of ASC 842 (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease liability	$ 15,342
Right-of-use lease asset	$ 14,497
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 (Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Basic and Diluted EPS:
Net loss	$ (8,281)	$ (12,546)	$ (17,984)	$ (27,816)	$ (20,827)	$ (45,800)
Weighted-average common shares outstanding	52,369		50,443		52,004	50,346
Weighted-average unvested restricted stock (in shares)	(11)		(372)		(35)	(463)
Weighted-average common shares outstanding used to compute net loss per share	52,358		50,071		51,969	49,883
Basic and diluted net loss per share (usd per share)	$ (0.16)		$ (0.36)		$ (0.40)	$ (0.92)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Net Income (Loss) Per Share (Shares Excluded and Included in Calculation of Diluted Earnings Per Share) (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	4,456	1,789	3,893	1,721
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)	605	18	559	27
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)	5	301	24	244
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)	3,818	1,434	3,282	1,401
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	28	36	28	49

Revenues (Details)	6 Months Ended
Revenues (Details)	Jun. 30, 2019
Revenue from Contract with Customer [Abstract]
Payment terms	75 days

Revenues (Revenue Disaggregated by Sales Distribution Channel) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 37,870	$ 28,648	$ 70,286	$ 53,524
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Desktop
Disaggregation of Revenue [Line Items]
Revenues	$ 16,588	$ 13,663	$ 31,809	$ 27,972
Concentration risk, percentage	44.00%	48.00%	45.00%	52.00%
Mobile
Disaggregation of Revenue [Line Items]
Revenues	$ 21,282	$ 14,985	$ 38,477	$ 25,552
Concentration risk, percentage	56.00%	52.00%	55.00%	48.00%

Revenues (Revenue Disaggregated by Geographic Location) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 37,870	$ 28,648	$ 70,286	$ 53,524
United States
Disaggregation of Revenue [Line Items]
Revenue	25,790	18,966	47,276	34,470
International
Disaggregation of Revenue [Line Items]
Revenue	$ 12,080	$ 9,682	$ 23,010	$ 19,054

Fair Value Measurements (Financial Instruments) (Details) - Recurring - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 13,377	$ 13,692
Cash equivalents \| 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	13,377	13,692
Cash equivalents \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Cash equivalents \| 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
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		7,524
U.S. Treasury, government and agency debt securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		7,524
U.S. Treasury, government and agency debt securities \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0
U.S. Treasury, government and agency debt securities \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		$ 0

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Cash equivalents \| Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 13,377	$ 13,692

Other Balance Sheet Amounts (Investments in Marketable Securities) (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 0
Available-for-sale—short-term \| 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 (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Available-for-sale securities	$ 0		$ 0
Realized gain (loss)	0	$ 0	0	$ 0
Unrealized holding gain (losses) reclassified	0	0	0	0
Sale of available-for-sale securities		$ 6,100,000	0	$ 6,086,000
Restricted cash	$ 0		$ 0		$ 0

Other Balance Sheet Amounts (Accounts Payable and Accrued Expenses) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Accounts payable—seller	$ 202,463	$ 230,423
Accounts payable—trade	4,849	3,122
Accrued employee-related payables	5,845	6,133
Accounts payable and accrued expenses	$ 213,157	$ 239,678

Intangible Assets (Finite-Lived Intangible Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	$ 17,588	$ 17,588
Total accumulated amortization—intangible assets	(8,999)	(7,414)
Total	8,589	10,174
Developed technology
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	16,878	16,878
Total accumulated amortization—intangible assets	(8,301)	(6,888)
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	690	690
Total accumulated amortization—intangible assets	(678)	(506)
Trademarks
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, gross	20	20
Total accumulated amortization—intangible assets	$ (20)	$ (20)

Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense of intangible assets	$ 0.8	$ 0.8	$ 1.6	$ 1.6

Intangible Assets (Finite-Lived Intangible Assets, Future Amortization Expense) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Remaining 2019	$ 1,425
2020	2,826
2021	2,826
2022	1,512
2023	0
Thereafter	0
Total	$ 8,589	$ 10,174

Stock-Based Compensation (Details)	6 Months Ended
Stock-Based Compensation (Details)	Jun. 30, 2019 shares
Number of Shares
Number of shares available for grant	4,444,960
Two Year RSUs
Number of Shares
Vesting period	2 years
Award vesting rights, percentage	50.00%
Stock Option
Number of Shares
Vesting period	4 years
Stock Option \| Vesting after one year of service
Number of Shares
Award vesting rights, percentage	25.00%
RSAs and RSUs \| Vesting after one year of service
Number of Shares
Award vesting rights, percentage	25.00%

Stock-Based Compensation (Stock Options Outstanding) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares
Shares Under Option
Beginning balance (in shares) \| shares	3,488
Granted (in shares) \| shares	1,184
Exercised (in shares) \| shares	(156)
Expired (in shares) \| shares	(35)
Forfeited (in shares) \| shares	(73)
Ending balance (in shares) \| shares	4,408
Exercisable (in shares) \| shares	2,340
Weighted- Average Exercise Price
Beginning balance (usd per share) \| $ / shares	$ 7.06
Granted (usd per share) \| $ / shares	4.98
Exercised (usd per share) \| $ / shares	2.46
Expired (usd per share) \| $ / shares	14.13
Forfeited (usd per share) \| $ / shares	2.62
Ending balance (usd per share) \| $ / shares	6.68
Exercisable (usd per share) \| $ / shares	$ 8.69
Weighted- Average Contractual Life
Outstanding	7 years 5 months 12 days
Exercisable	6 years 25 days
Aggregate Intrinsic Value
Outstanding, aggregate intrinsic value \| $	$ 6,829
Exercisable, aggregate intrinsic value \| $	$ 2,720

Stock-Based Compensation (Stock Options Narrative) (Details) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares
Number of Shares
Intrinsic values of options exercised	$ 0.6
Unrecognized employee stock-based compensation	$ 5.2
Weighted average grant date fair value (usd per share) \| $ / shares	$ 2.85
Fair value of options vested in period	$ 1.0
Stock Option
Number of Shares
Unrecognized employee stock-based compensation, period for recognition	2 years 10 months 24 days

Stock-Based Compensation (Valuation Assumptions) (Details) - Stock Option	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Number of Shares
Expected term	6 years 1 month 6 days	6 years 1 month 6 days
Risk-free interest rate	2.51%	2.66%
Expected volatility	60.00%	57.00%
Dividend yield	0.00%	0.00%

Stock-Based Compensation (Restricted Stock Activity) (Details) - Restricted Stock Awards shares in Thousands	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Number of Shares Rollforward
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 (Restricted Stock Narrative) (Details) - Unvested restricted stock awards $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Number of Shares
Fair value of restricted stock vested	$ 0.1
Unrecognized employee stock-based compensation	$ 0.1
Unrecognized employee stock-based compensation, period for recognition	10 months 24 days

Stock-Based Compensation (Restricted Stock Units Activity) (Details) - Restricted Stock Units (RSUs) shares in Thousands	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Number of Shares
Beginning balance (in shares) \| shares	6,100
Granted (in shares) \| shares	4,668
Canceled (in shares) \| shares	(288)
Vested (in shares) \| shares	(2,193)
Ending balance (in shares) \| shares	8,287
Weighted-Average Grant Date Fair Value
Beginning balance (in dollars per share) \| $ / shares	$ 3.56
Granted (in dollars per share) \| $ / shares	4.68
Canceled (in dollars per share) \| $ / shares	3.58
Vested (in dollars per share) \| $ / shares	3.39
Ending balance (in dollars per share) \| $ / shares	$ 4.24

Stock-Based Compensation (Restricted Stock Units Narrative) (Details) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares
Restricted Stock Units (RSUs)
Number of Shares
Granted (in dollars per share) \| $ / shares	$ 4.68
Fair value of restricted stock vested	$ 11.2
Intrinsic value of nonvested unit	52.7
Unrecognized employee stock-based compensation	$ 29.8
Unrecognized employee stock-based compensation, weighted average period	2 years 6 months
Two Year RSUs
Number of Shares
Restricted Stock units included units granted (in shares) \| shares	1.6
Award vesting rights, percentage	50.00%
Vesting period	2 years

Stock-Based Compensation (Employee Stock Purchase Plan Narrative) (Details)	6 Months Ended
	Jun. 30, 2019 shares
Number of Shares
Number of shares reserved	4,444,960
Employee Stock
Number of Shares
Annual % increase	1.00%
2014 Employee Stock Purchase Plan \| Employee Stock
Number of Shares
Maximum employee subscription rate	10.00%
Purchase price of common stock, percent	85.00%
Number of shares reserved	2,001,256

Stock-Based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 4,795	$ 4,612	$ 9,164	$ 9,156
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	106	77	198	184
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,459	1,158	2,804	2,343
Technology and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,166	623	2,225	1,472
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	2,064	2,402	3,937	4,759
Restructuring and other exit costs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 0	$ 352	$ 0	$ 398

Restructuring and Other Exit Costs (Schedule of Restructuring and Other Exit Costs) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Restructuring Reserve [Roll Forward]
Accrued restructuring and other exit costs, beginning balance			$ 100,000	$ 0
Restructuring and other exit costs	$ 0	$ 974,000	0	3,440,000
Cash paid for restructuring and other exit costs				(2,561,000)
Non-cash stock-based compensation for restructuring and other exit costs				(398,000)
Restructuring and other exit costs	$ 0	974,000	$ 0	3,440,000
Accrued restructuring and other exit costs, ending balance		$ 481,000		$ 481,000

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Provision (benefit) for income taxes	$ 84	$ 74	$ (624)	$ 149

Commitments and Contingencies (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Office Lease \| Financial Standby Letter of Credit
Other Commitments [Line Items]
Letters of credit outstanding, amount	$ 3.7	$ 2.9

Lease Obligations (Details) - USD ($)	3 Months Ended		6 Months Ended
Lease Obligations (Details) - USD ($)	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term	3 years 1 month 6 days		3 years 1 month 6 days
Weighted average discount rate, percent	5.20%		5.20%
Lease expense	$ 1,800,000		$ 3,600,000
Short-term lease expense	200,000		400,000
Rental expense under ASC 840		$ 3,300,000		$ 6,500,000
Sublease income under ASC 842	46,200		200,000
Sublease income, under ASC 840		$ 200,000		$ 400,000
Lease not yet commenced, expected lease liability	$ 9,000,000		$ 9,000,000
Minimum
Lessee, Lease, Description [Line Items]
Lease terms	1 year		1 year
Maximum
Lessee, Lease, Description [Line Items]
Lease terms	7 years		7 years

Lease Obligations (Schedule of Lease Liability Maturities) (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Leases [Abstract]
Remaining 2019	$ 3,808
2020	6,795
2021	3,043
2022	1,096
2023	809
Thereafter	1,046
Total lease payments (undiscounted)	16,597
Less: imputed interest	(1,255)
Lease liabilities—total (discounted)	$ 15,342

Debt (Details)	6 Months Ended
Debt (Details)	Jun. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Debt Instrument [Line Items]
Adjusted Quick Ratio	1.16
Revolving Credit Facility \| Loan Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 40,000,000.0
Capitalized debt issuance costs		$ 100,000
Unused capacity fee, percentage	0.15%
Adjusted Quick Ratio, in streamline period	1.05
Revolving Credit Facility \| Covenant Compliance Period One \| Loan Agreement
Debt Instrument [Line Items]
Adjusted EBITDA threshold	0.20
Revolving Credit Facility \| Covenant Compliance Period Two \| Loan Agreement
Debt Instrument [Line Items]
Adjusted EBITDA minimum	$ 1
Revolving Credit Facility \| Covenant Compliance Period Three \| Loan Agreement
Debt Instrument [Line Items]
Adjusted EBITDA minimum	$ 5,000,000.0
Streamline Period Applies \| Revolving Credit Facility \| Loan Agreement \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate	2.50%
Streamline Period Applies \| Revolving Credit Facility \| Loan Agreement \| Prime Rate
Debt Instrument [Line Items]
Variable interest rate	0.50%
Streamline Period Does Not Apply \| Revolving Credit Facility \| Loan Agreement \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Variable interest rate	4.00%
Streamline Period Does Not Apply \| Revolving Credit Facility \| Loan Agreement \| Prime Rate
Debt Instrument [Line Items]
Variable interest rate	2.00%
Covenant Term, Scenario One \| Revolving Credit Facility \| Loan Agreement
Debt Instrument [Line Items]
Adjusted Quick Ratio	1.00
Adjusted EBITDA maximum	$ 0
Covenant Term, Scenario Two \| Revolving Credit Facility \| Loan Agreement
Debt Instrument [Line Items]
Adjusted Quick Ratio	0.90
Adjusted EBITDA minimum	$ 0