ChannelAdvisor (ECOM) 10-K 25 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 11, 2016	Jun. 30, 2015
Document Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Entity Registrant Name	CHANNELADVISOR CORP
Entity Central Index Key	1,169,652
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		25,243,168
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 259,931,907

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets
Cash and cash equivalents	$ 60,474	$ 68,366
Accounts receivable, net of allowance of $785 and $673 as of December 31, 2015 and 2014, respectively	18,949	14,619
Prepaid expenses and other current assets	9,356	4,940
Total current assets	88,779	87,925
Property and equipment, net	16,696	12,603
Goodwill	21,632	21,518
Intangible assets, net	3,246	4,083
Restricted cash	67	633
Other assets	536	285
Total assets	130,956	127,047
Liabilities and stockholders' equity
Accounts payable	2,435	564
Accrued expenses	9,908	7,292
Deferred revenue	19,835	16,840
Other current liabilities	4,188	2,563
Total current liabilities	36,366	27,259
Long-term capital leases, net of current portion	2,031	2,014
Lease incentive obligation	5,084	119
Other long-term liabilities	3,551	4,007
Total liabilities	$ 47,032	$ 33,399
Commitments and contingencies (Note 6)
Stockholders' equity:
Preferred stock, $0.001 par value, 5,000,000 shares authorized, no shares issued and outstanding as of December 31, 2015 and 2014, respectively	$ 0	$ 0
Common stock, $0.001 par value, 100,000,000 shares authorized, 25,230,958 and 24,915,510 shares issued and outstanding as of December 31, 2015 and 2014, respectively	25	25
Additional paid-in capital	240,360	228,370
Accumulated other comprehensive loss	(893)	(130)
Accumulated deficit	(155,568)	(134,617)
Total stockholders' equity	83,924	93,648
Total liabilities and stockholders' equity	$ 130,956	$ 127,047

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 785	$ 673
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	25,230,958	24,915,510
Common stock, shares outstanding (in shares)	25,230,958	24,915,510

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenue	$ 100,585	$ 84,901	$ 68,004
Cost of revenue (excluding depreciation)	20,848	20,713	15,947
Depreciation - Cost of revenue	4,986	3,507	2,141
Gross profit	74,751	60,681	49,916
Operating expenses:
Sales and marketing	51,941	54,902	36,942
Research and development	16,060	16,215	12,426
General and administrative	24,136	20,815	13,332
Depreciation and amortization	3,807	2,757	1,581
Total operating expenses	95,944	94,689	64,281
Loss from operations	(21,193)	(34,008)	(14,365)
Other income (expense):
Loss on extinguishment of debt	0	0	(3,112)
Interest expense, net	(184)	(209)	(2,960)
Other income (expense), net	241	(256)	12
Total other income (expense)	57	(465)	(6,060)
Loss before income taxes	(21,136)	(34,473)	(20,425)
Income tax (benefit) expense	(185)	41	203
Net loss	$ (20,951)	$ (34,514)	$ (20,628)
Net loss per share:
Basic and diluted (in dollars per share)	$ (0.84)	$ (1.40)	$ (1.51)
Weighted average common shares outstanding:
Basic and diluted (in shares)	25,062,610	24,619,714	13,695,804

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net loss	$ (20,951)	$ (34,514)	$ (20,628)
Other comprehensive loss:
Foreign currency translation adjustments	(763)	341	(182)
Total comprehensive loss	$ (21,714)	$ (34,173)	$ (20,810)

Consolidated Statement of Chang

Consolidated Statement of Changes in Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning balance (in shares) at Dec. 31, 2012		1,240,193
Beginning balance, amount at Dec. 31, 2012	$ (76,179)	$ 1	$ 3,584	$ (289)	$ (79,475)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock (in shares)		13,401,499
Conversion of redeemable convertible preferred stock to common stock, amount	91,150	$ 13	91,137
Conversion of redeemable convertible preferred stock warrants to common stock warrants	3,632		3,632
Exercise of stock options and vesting of restricted stock units (in shares)		727,318
Exercise of stock options and vesting of restricted stock units, amount	2,448	$ 1	2,447
Issuance of common stock from public offerings, net of issuance costs (in shares)		7,612,500
Issuance of common stock from public offerings, net of issuance costs, amount	113,848	$ 8	113,840
Exercise of common stock warrants (in shares)		662,362
Exercise of common stock warrants, amount	1,592	$ 1	1,591
Stock-based compensation expense	2,099		2,099
Net loss	(20,628)				(20,628)
Foreign currency translation adjustments	(182)			(182)
Ending balance (in shares) at Dec. 31, 2013		23,643,872
Ending balance, amount at Dec. 31, 2013	117,780	$ 24	218,330	(471)	(100,103)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock, amount	0
Exercise of stock options and vesting of restricted stock units (in shares)		607,580
Exercise of stock options and vesting of restricted stock units, amount	2,060	$ 0	2,060
Exercise of common stock warrants (in shares)		664,058
Exercise of common stock warrants, amount	0	$ 1	(1)
Stock-based compensation expense	7,981		7,981
Net loss	(34,514)				(34,514)
Foreign currency translation adjustments	341			341
Ending balance (in shares) at Dec. 31, 2014		24,915,510
Ending balance, amount at Dec. 31, 2014	93,648	$ 25	228,370	(130)	(134,617)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock, amount	0
Exercise of stock options and vesting of restricted stock units (in shares)		386,654
Exercise of stock options and vesting of restricted stock units, amount	892	$ 0	892
Stock-based compensation expense	11,837		11,837
Statutory tax withholding related to net-share settlement of RSUs (in shares)		(71,206)
Statutory tax withholding related to net-share settlement of RSUs, amount	(739)		(739)
Net loss	(20,951)				(20,951)
Foreign currency translation adjustments	(763)			(763)
Ending balance (in shares) at Dec. 31, 2015		25,230,958
Ending balance, amount at Dec. 31, 2015	$ 83,924	$ 25	$ 240,360	$ (893)	$ (155,568)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities
Net loss	$ (20,951)	$ (34,514)	$ (20,628)
Adjustments to reconcile net loss to net cash and cash equivalents used in operating activities:
Depreciation and amortization	8,793	6,264	3,722
Loss on extinguishment of debt	0	0	3,112
Bad debt expense	1,236	1,315	527
Change in fair value of preferred stock warrants	0	0	1,052
Accretion of debt discount	0	0	547
Non-cash stock-based compensation expense	11,837	7,981	2,099
Other items, net	(329)	142	5
Changes in assets and liabilities:
Accounts receivable	(5,833)	(1,407)	(4,917)
Prepaid expenses and other assets	(3,487)	(1,106)	(1,026)
Restricted cash	566	52	(1)
Accounts payable and accrued expenses	3,608	(2,709)	5,723
Deferred revenue	3,101	2,447	4,471
Net cash and cash equivalents used in operating activities	(1,459)	(21,535)	(5,314)
Cash flows from investing activities
Purchases of property and equipment	(4,062)	(5,971)	(3,711)
Payment of internal-use software development costs	(190)	(846)	(1,507)
Acquisition, net of cash acquired	0	(8,034)	0
Net cash and cash equivalents used in investing activities	(4,252)	(14,851)	(5,218)
Cash flows from financing activities
Proceeds from issuance of common stock, net of underwriting discounts and commissions	0	0	118,463
Repayment of debt and capital leases	(1,745)	(1,699)	(14,230)
Payment of debt extinguishment costs	0	0	(1,200)
Payment of deferred offering costs	0	0	(2,909)
Proceeds from exercise of common stock warrants	0	0	1,592
Proceeds from exercise of stock options	892	2,060	2,448
Payment of statutory tax withholding related to net-share settlement of restricted stock units	(739)	0	0
Net cash and cash equivalents (used in) provided by financing activities	(1,592)	361	104,164
Effect of currency exchange rate changes on cash and cash equivalents	(589)	(15)	(91)
Net (decrease) increase in cash and cash equivalents	(7,892)	(36,040)	93,541
Cash and Cash Equivalents, beginning of period	68,366	104,406	10,865
Cash and Cash Equivalents, end of period	60,474	68,366	104,406
Supplemental disclosure of cash flow information
Cash paid for interest	155	273	1,334
Cash paid for income taxes, net	170	53	92
Supplemental disclosure of noncash investing and financing activities
Conversion of redeemable convertible preferred stock to common stock	0	0	91,150
Conversion of preferred stock warrants to common stock warrants	0	0	3,632
Deferred offering costs included in accounts payable and accrued expenses	0	0	73
Accrued capital expenditures	563	0	627
Capital lease obligations entered into for the purchase of fixed assets	2,207	2,431	1,454
Other acquisition consideration	0	200	0
Non-cash leasehold improvements	$ 5,263	$ 0	$ 0

Description of the Business

Description of the Business	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business	Description of the Business ChannelAdvisor Corporation (“ChannelAdvisor” or the “Company”) was incorporated in the state of Delaware and capitalized in June 2001. The Company began operations in July 2001. ChannelAdvisor is a provider of software-as-a-service, or SaaS, solutions that allow retailers and branded manufacturers to integrate, manage and monitor their merchandise sales across hundreds of online channels. The Company is headquartered in Morrisville, North Carolina and has international offices in England, Ireland, Germany, Australia, Brazil and China.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. Reclassification Certain prior period amounts included on the condensed consolidated statements of operations have been reclassified to conform to the current period’s presentation. In order to gain further clarity and understanding of its operating results, the Company will now present depreciation and amortization expense separately on the condensed consolidated statements of operations. Previously, depreciation and amortization expense was included in cost of revenue and operating expenses. These reclassifications had no effect on the Company's reported gross profit and net loss for the years ended December 31, 2014 and 2013 . The tables below summarize these reclassifications (in thousands): Year Ended December 31, 2014 As Previously Reported Reclassification As Reclassified Cost of revenue (excluding depreciation) $ 24,220 $ (3,507 ) $ 20,713 Depreciation - Cost of revenue — 3,507 3,507 Sales and marketing 55,829 (927 ) 54,902 Research and development 16,585 (370 ) 16,215 General and administrative 22,275 (1,460 ) 20,815 Depreciation and amortization — 2,757 2,757 Year Ended December 31, 2013 As Previously Reported Reclassification As Reclassified Cost of revenue (excluding depreciation) $ 18,088 $ (2,141 ) $ 15,947 Depreciation - Cost of revenue — 2,141 2,141 Sales and marketing 37,458 (516 ) 36,942 Research and development 12,669 (243 ) 12,426 General and administrative 14,154 (822 ) 13,332 Depreciation and amortization — 1,581 1,581 Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"), which provides new guidance for revenue recognition. ASU 2014-09 provides that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 also requires improved disclosures to help users of financial statements better understand the nature, amount, timing, and uncertainty of revenue that is recognized. Entities have the option of using either a full retrospective or modified retrospective approach for the adoption of the standard. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date , which resulted in a one year deferral of the effective date of ASU 2014-09 to annual reporting periods beginning after December 15, 2017. Early adoption is permitted for annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. The Company is currently evaluating the impact the adoption of ASU 2014-09 will have on its consolidated financial statements. In September 2015, the FASB issued ASU No. 2015-16, Simplifying the Accounting for Measurement-Period Adjustments (Topic 805) ("ASU 2015-16"), which eliminates the requirement that an acquirer in a business combination account for measurement-period adjustments retrospectively. ASU 2015-16 requires that the cumulative impact of measurement-period adjustments, including prior period amounts, be recognized in the reporting period in which the adjustment is identified. The update is effective for fiscal years beginning after December 15, 2015. The Company has elected to early adopt ASU 2015-16; however, the adoption of this pronouncement did not have a material impact on the Company’s results of operations, financial position or cash flows. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes (Topic 740) ("ASU 2015-17"), which requires that all deferred tax assets and liabilities, including any related valuation allowance, be classified as noncurrent on the balance sheet. The update is effective for fiscal years beginning after December 15, 2016 and early adoption is permitted. The guidance may be applied either prospectively or retrospectively. The Company is currently evaluating the impact the adoption of ASU 2015-17 will have on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"), which requires that lessees recognize assets and liabilities for leases with lease terms greater than twelve months in the statement of financial position. ASU 2016-02 also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. The update is effective for fiscal years beginning after December 15, 2018, including interim reporting periods within that reporting period. Early adoption is permitted. The Company is currently evaluating the impact the adoption of ASU 2016-02 will have on its consolidated financial statements. The Company has reviewed other new accounting pronouncements that were issued as of December 31, 2015 and does not believe that these pronouncements are applicable to the Company, or that they will have a material impact on its financial position or results of operations. Use of Estimates The preparation of financial statements in conformity with United States generally accepted accounting principles (“U.S. GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those related to the accounts receivable allowance, the useful lives of long-lived assets and other intangible assets, income taxes and assumptions used for purposes of determining stock-based compensation, among others. Estimates and assumptions are also required to value assets acquired and liabilities assumed as well as contingent consideration, where applicable, in conjunction with business combinations. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable, the results of which form the basis for making judgments about the carrying value of assets and liabilities. Cash and Cash Equivalents The Company considers all highly liquid investments maturing within ninety days or less at the time of purchase to be cash equivalents. Cash and cash equivalents are comprised of cash and money market funds. Due to the short-term nature and liquidity of these financial instruments, the carrying value of these assets approximates fair value. Restricted Cash Restricted cash represents cash that is not readily available for general purpose cash needs. As of December 31, 2014, the Company had restricted cash of $0.6 million related to its operations in the United States. The majority of this amount had been used as collateral for potential chargebacks resulting from the Company’s processing of customers’ credit cards. The Company is no longer required to set aside funds as collateral for potential chargebacks and therefore its restricted cash balance as of December 31, 2015 is nominal. Revenue Recognition and Deferred Revenue The majority of the Company’s revenue is derived from subscription fees paid by customers for access to and usage of the Company’s cloud-based SaaS platform for a specified period of time, which is typically one year. A portion of the subscription fee is typically fixed and is based on a specified minimum amount of gross merchandise value (“GMV”) that a customer expects to process through the Company’s platform over the contract term. The remaining portion of the subscription fee is variable and is based on a specified percentage of GMV processed through the Company’s platform in excess of the customer’s specified minimum amount. In addition, other sources of revenue consist primarily of implementation fees, which may include fees for providing launch assistance and training. Implementation services are provided at the customer's option and are not essential to the functionality of the Company's platform, nor is the customer required to purchase these services in order to access the Company's platform. The Company also generates revenue from its solutions that allow branded manufacturers to direct potential consumers from their websites and digital marketing campaigns to authorized resellers. These contacts are generally one year in duration. The Company recognizes revenue when there is persuasive evidence of an arrangement, the service has been provided to the customer, the collection of the fee is reasonably assured and the amount of the fee to be paid by the customer is fixed or determinable. The Company’s contractual arrangements include performance, termination and cancellation provisions, but do not provide for refunds. Customers do not have the contractual right to take possession of the Company’s software at any time. The Company’s arrangements generally contain multiple elements comprised of subscription and implementation services. The Company evaluates each element in an arrangement to determine whether it represents a separate unit of accounting. An element constitutes a separate unit of accounting when the delivered item has standalone value and delivery of the undelivered element is probable and within the Company’s control. The Company’s implementation services are not sold separately from the subscription and there is no alternative use for them. As such, the Company has determined the implementation services do not have standalone value. Accordingly, subscription and implementation services are combined and recognized as a single unit of accounting. The Company generally recognizes the fixed portion of subscription fees and implementation fees ratably over the contract term. Recognition begins when the customer has access to the Company’s platform or to its solutions for branded manufacturers and transactions can be processed, provided all other revenue recognition criteria have been met. Some customers elect a managed-service solution and contract with the Company to manage some or all aspects of the Company’s SaaS solutions on the customer’s behalf for a specified period of time, which is typically one year. Under these managed-service arrangements, customer transactions cannot be processed through the Company’s platform until the completion of the implementation services. As such, revenue is contingent upon the Company’s completion of the implementation services and recognition commences when transactions can be processed on the Company’s platform, provided all other revenue recognition criteria have been satisfied. At that time, the Company recognizes a pro-rata portion of the fees earned since the inception of the arrangement. The balance of the fees is recognized ratably over the remaining contract term. The Company recognizes the variable portion of subscription fee revenue in the period in which the related GMV is processed, provided all other revenue recognition criteria have been met. Sales taxes collected from customers and remitted to government authorities are excluded from revenue. Deferred revenue represents the unearned portion of fixed subscription fees and implementation fees. Deferred amounts are generally recognized within one year. Those amounts that are expected to be recognized in greater than one year are recorded in other long-term liabilities in the accompanying condensed consolidated balance sheets. Sales Commissions Sales commissions are expensed when the related subscription agreement is executed by the customer. Cost of Revenue Cost of revenue primarily consists of personnel and related costs, including salaries, bonuses, payroll taxes and stock-based compensation, co-location facility costs for the Company’s data centers, depreciation expense for computer equipment directly associated with generating revenue, credit card transaction fees and infrastructure maintenance costs. In addition, the Company allocates a portion of overhead, such as rent, additional depreciation and amortization and employee benefits costs, to cost of revenue based on headcount. Fair Value of Financial Instruments The Company uses a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires the Company to use observable inputs when available, and to minimize the use of unobservable inputs when determining fair value. The three tiers are defined as follows: • Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities; • Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and • Level 3. Unobservable inputs for which there is little or no market data, which require the Company to develop its own assumptions. The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate their respective fair values due to their short-term nature. The acquisition of E-Tale includes a contingent consideration arrangement that allows for adjustment of payments based upon achievement of specified quarterly revenue targets through June 2017. Contingent consideration was measured at fair value at the acquisition date and is remeasured to fair value at each reporting date until the contingency is resolved. The fair value is reported within other current liabilities and other long-term liabilities on the consolidated balance sheets. Increases or decreases in any valuation inputs in isolation may result in a significantly lower or higher fair value measurement in the future. Subsequent changes in the fair value of contingent consideration are recognized within general and administrative expenses in the Company’s consolidated statements of operations. The fair value of contingent consideration related to the E-Tale acquisition is based on projected quarterly revenue targets for E-Tale through June 2017. The Company discounted the expected future earn-out payment to net present value using Level 3 inputs. A key assumption used in the measurement of fair value of contingent consideration includes a discount rate of 22% and 24% as of December 31, 2015 and 2014 , respectively. The Company believes the discount rate used to discount the earn-out payments reflects market participant assumptions. Projected revenue is based on the Company’s internal projections and analysis of the current customer base and expected customer growth, target market and sales potential. The following table presents changes to the Company's liability for acquisition-related contingent consideration for the year ended December 31, 2015 (in thousands): Balance, as of January 1, 2015 $ 618 Change in contingent consideration fair value 79 Balance, as of December 31, 2015 $ 697 Concentration of Credit Risk Financial instruments that subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. All of the Company’s cash and cash equivalents are held at financial institutions that management believes to be of high credit quality. The Company’s cash and cash equivalents accounts exceed federally insured limits. The Company has not experienced any losses on its cash and cash equivalents accounts to date. To manage accounts receivable risk, the Company maintains an allowance for doubtful accounts. The Company did not have any customers that individually comprised a significant concentration of its accounts receivable as of December 31, 2015 and 2014 , or a significant concentration of its revenue for the years ended December 31, 2015 , 2014 and 2013 . Accounts Receivable and Allowance for Doubtful Accounts The Company extends credit to customers without requiring collateral. Accounts receivable are stated at realizable value, net of an allowance for doubtful accounts. The Company utilizes the allowance method to provide for doubtful accounts based on management’s evaluation of the collectability of amounts due. The Company’s estimate is based on historical collection experience and a review of the current status of accounts receivable. Historically, actual write-offs for uncollectible accounts have not significantly differed from the Company’s estimates. The following table presents the changes in the Company’s allowance for doubtful accounts during the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at Beginning of Period Additions Charged To Expense/ Against Revenue Deductions Balance at End of Period Allowance for doubtful accounts: Year ended December 31, 2015 $ 673 1,315 (1,203 ) $ 785 Year ended December 31, 2014 $ 561 737 (625 ) $ 673 Year ended December 31, 2013 $ 191 594 (224 ) $ 561 Other Receivables Under certain customer arrangements, the Company collects and remits monthly activity-based fees incurred on specific channels on the customers’ behalf. The Company records the amounts due from customers as a result of these arrangements as other receivables. Other receivables of $4.7 million and $1.3 million are included in prepaid expenses and other current assets on the consolidated balance sheets as of December 31, 2015 and 2014 , respectively. Property and Equipment Property and equipment are recorded at cost. Expenditures for major additions and improvements are capitalized. Depreciation and amortization is provided over the estimated useful lives of the related assets using the straight-line method. The estimated useful lives for significant property and equipment categories are generally as follows: Purchased software, including internal-use software 3 years Computer hardware 3 years Furniture and office equipment 3 to 5 years Leasehold improvements Lesser of remaining lease term or useful life Repairs and maintenance costs are expensed as incurred. Identifiable Intangible Assets The Company acquired intangible assets in connection with its business acquisitions. See Note 3 included in this Annual Report for information regarding intangible assets acquired in connection with the acquisition of E-Tale. These assets were recorded at their estimated fair values at the acquisition date and are being amortized over their respective estimated useful lives using the straight-line method. The estimated useful lives and amortization methodology used in computing amortization are as follows: Estimated Useful Lives Amortization Methodology Customer relationships 7 years Straight-line Acquired technology 7 years Straight-line Trade names 3 years Straight-line Impairment of Long-Lived Assets The Company reviews long-lived assets and definite-lived intangible assets for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Recoverability of the long-lived asset is measured by a comparison of the carrying amount of the asset or asset group to future undiscounted net cash flows expected to be generated by the asset or asset group. If such assets are not recoverable, the impairment to be recognized, if any, is measured by the amount by which the carrying amount of the assets exceeds the estimated fair value of the assets or asset group. Assets held for sale are reported at the lower of the carrying amount or fair value, less costs to sell. As of December 31, 2015 and 2014 , management does not believe any long-lived assets are impaired and has not identified any assets as being held for sale. Goodwill Goodwill represents the excess of the aggregate of the fair value of consideration transferred in a business combination over the fair value of assets acquired, net of liabilities assumed. The Company recorded goodwill in connection with its business acquisitions. See Note 3 and Note 5 below for information regarding goodwill recorded in connection with the acquisition of E-Tale. Goodwill is not amortized, but is subject to an annual impairment test. The Company tests goodwill for impairment annually on December 31, or more frequently if events or changes in business circumstances indicate the asset might be impaired. The Company has determined that it has a single, entity-wide reporting unit. The Company first assessed qualitative factors to determine whether it was more likely than not that the fair value of its single reporting unit was less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test under ASU No. 2011-08, Goodwill and Other (Topic 350): Testing Goodwill for Impairment. If the qualitative factors had indicated that it was more likely than not that the fair value of the reporting unit was less than its carrying amount, the Company would have tested goodwill for impairment at the reporting unit level using a two-step approach. The first step is to compare the fair value of the reporting unit to the carrying value of the net assets assigned to the reporting unit. If the fair value of the reporting unit is greater than the carrying value of the net assets assigned to the reporting unit, the assigned goodwill is not considered impaired. If the fair value is less than the reporting unit’s carrying value, step two is performed to measure the amount of the impairment, if any. In the second step, the fair value of goodwill is determined by deducting the fair value of the reporting unit’s identifiable assets and liabilities from the fair value of the reporting unit as a whole, as if the reporting unit had just been acquired and the fair value was being initially allocated. If the carrying value of goodwill exceeds the implied fair value, an impairment charge would be recorded in the period the determination is made. As a result of the Company’s annual impairment test as of December 31, 2015 and 2014 , goodwill was not considered impaired and, as such, no impairment charges were recorded. Advertising Costs The Company expenses advertising costs as incurred. The amount expensed during the years ended December 31, 2015 , 2014 and 2013 was $4.3 million , $6.3 million and $4.6 million , respectively. Software Development Costs The Company capitalizes certain internal-use software development costs, consisting primarily of direct labor associated with creating the internally developed software and third-party consulting fees associated with implementing software purchased for internal use. Software development projects generally include three stages: the preliminary project stage (in which all costs are expensed as incurred), the application development stage (in which certain costs are capitalized) and the post-implementation/operation stage (in which all costs are expensed as incurred). The costs incurred during the application development stage primarily include the costs of designing the application, coding and testing of the system. Capitalized costs are amortized using the straight-line method over the estimated useful life of the software once it is ready for its intended use. Software development costs of $0.2 million and $0.4 million related to creating internally developed software and implementing software purchased for internal use were capitalized during the years ended December 31, 2015 and 2014 , respectively, and are included in property and equipment in the accompanying consolidated balance sheets. Amortization expense related to capitalized internally developed software was $0.3 million , $0.2 million and $0.1 million for the years ended December 31, 2015 , 2014 and 2013 , respectively, and is included in cost of revenue or general and administrative expense in the accompanying consolidated statements of operations, depending upon the nature of the software development project. The net book value of capitalized internally developed software was $0.4 million and $0.6 million at December 31, 2015 and 2014 , respectively. Software development costs of $0.3 million related to configuring and implementing hosted third-party software applications that the Company will use in its business operations were capitalized during the year ended December 31, 2014. There were no amounts capitalized during the year ended December 31, 2015 . These costs are included in property and equipment in the accompanying consolidated balance sheets. Amortization expense related to hosted third-party software applications was $0.6 million , $0.7 million and $0.1 million for the years ended December 31, 2015 , 2014 and 2013, respectively, and is included in general and administrative expense in the accompanying consolidated statements of operations. The net book value of hosted third-party software applications was $0.6 million and $1.4 million as of December 31, 2015 and 2014 , respectively. Income Taxes Income taxes are accounted for under the asset and liability method of accounting. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, as well as for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the results of operations in the period that includes the enactment date. The measurement of a deferred tax asset is reduced, if necessary, by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized. The Company applies the accounting guidance for uncertainties in income taxes, which prescribes a recognition threshold and measurement process for recording uncertain tax positions taken, or expected to be taken, in a tax return in the financial statements. Additionally, the guidance also prescribes the treatment for the derecognition, classification, accounting in interim periods and disclosure requirements for uncertain tax positions. The Company accrues for the estimated amount of taxes for uncertain tax positions if it is more likely than not that the Company would be required to pay such additional taxes. An uncertain tax position will be recognized if it is more likely than not to be sustained. The Company did not have any accrued interest or penalties associated with unrecognized tax positions as of December 31, 2015 and 2014 . Foreign Currency Translation The functional currency of the Company’s non-U.S. operations is the local currency. Monetary assets and liabilities denominated in foreign currencies are translated into U.S. dollars at exchange rates prevailing at the balance sheet dates. Non-monetary assets and liabilities are translated at the historical rates in effect when the assets were acquired or obligations incurred. Revenue and expenses are translated into U.S. dollars using the average rates of exchange prevailing during the period. Gains or losses resulting from the translation of assets and liabilities are included as a component of accumulated other comprehensive loss in stockholders’ equity. Gains and losses resulting from foreign currency transactions are recognized as other (expense) income. Stock-Based Compensation The Company accounts for stock-based compensation awards, which include stock options and restricted stock units ("RSUs"), based on the fair value of the award as of the grant date. The Company recognizes stock-based compensation expense using the accelerated attribution method, net of estimated forfeitures, in which compensation cost for each vesting tranche in an award is recognized ratably from the service inception date to the vesting date for that tranche. The Company uses the Black-Scholes option pricing model for estimating the fair value of stock options. The use of the option valuation model requires the input of the Company's stock price, as well as highly subjective assumptions, including the expected life of the option and the expected stock price volatility based on peer companies. Additionally, the recognition of expense requires the estimation of the number of awards that will ultimately vest and the number of awards that will ultimately be forfeited. The fair value of the Company's common stock, for purposes of determining the grant date fair value of option and RSU awards, has been determined by using the closing market price per share of common stock as quoted on the New York Stock Exchange on the date of grant. Basic and Diluted Loss per Common Share Diluted loss per share is the same as basic loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive given the Company’s net loss.

Business Combination

Business Combination	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Business Combination	Business Combination On October 31, 2014, the Company’s wholly owned subsidiary, ChannelAdvisor UK Limited (“ChannelAdvisor UK”), entered into a Securities Purchase Agreement (the “Purchase Agreement”) pursuant to which ChannelAdvisor UK acquired all of the issued and outstanding shares of E-Tale, a UK-based company that offers a global Where to Buy solution. ChannelAdvisor UK acquired E-Tale to expand its e-commerce support for branded manufacturers. The Where to Buy solution allows branded manufacturers to send their web visitors directly to authorized resellers and to gain insight into consumer behavior. Under the Purchase Agreement, ChannelAdvisor UK paid to the shareholders of E-Tale a cash purchase price of $8.2 million , which was subject to adjustment as set forth in the Purchase Agreement and discussed below. The cash consideration included $1.0 million that has been placed into escrow to secure the indemnification obligations of E-Tale’s shareholders until April 30, 2016. The initial aggregate purchase price totaled $9.0 million , which was comprised of $8.2 million of cash, $0.6 million for contingent consideration noted below and $0.2 million of other items. During the year ended December 31, 2015, the aggregate purchase price was adjusted by less than $0.1 million for post-closing working capital adjustments, in accordance with the Purchase Agreement. In connection with the acquisition of E-Tale, ChannelAdvisor UK incurred an obligation to make contingent earn-out payments up to $4.0 million to the former shareholders of E-Tale, most of whom are now employees of the Company, based upon the achievement of specified quarterly revenue targets through June 2017. Pursuant to Accounting Standards Codification Topic 805, Business Combinations ("ASC 805"), this contingent consideration is deemed to be part of the purchase price and is recorded as a liability based on the estimated fair value of the consideration ChannelAdvisor UK expects to pay as of the acquisition date. Refer to Note 2, "Significant Accounting Policies—Fair Value of Financial Instruments" for more information regarding the key assumptions used in determining the fair value of the contingent consideration. As of December 31, 2015, $0.7 million of contingent consideration was recorded as a liability on the Company's consolidated balance sheet. The acquisition has been accounted for under the acquisition method of accounting in accordance with ASC 805. Under the acquisition method of accounting, the Company allocated the purchase price to the identifiable assets acquired and liabilities assumed based on their estimated acquisition-date fair value. The Company's allocation of the total purchase consideration is as follows (in thousands): Cash $ 124 Accounts receivable 506 Customer relationships 2,100 Acquired technology 1,700 Trade names 130 Deferred tax liability (794 ) Other assets/liabilities, net (334 ) Goodwill 5,526 Total purchase price $ 8,958 The difference between the acquisition-date fair value of the consideration and the estimated fair value of the net assets acquired is recorded as goodwill. Goodwill represents the future economic benefits expected to arise from other intangible assets acquired that do not qualify for separate recognition, including acquired workforce, as well as expected future synergies. Goodwill is not deductible for tax purposes. During the year ended December 31, 2014, ChannelAdvisor UK incurred transaction costs in connection with the acquisition of $0.5 million , which are included in general and administrative expense in the accompanying consolidated statements of operations. Comparative pro forma financial information for this acquisition has not been presented because the acquisition is not material to the Company’s consolidated results of operations.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment consisted of the following as of December 31, 2015 and 2014 (in thousands): 2015 2014 Purchased software, including internal-use software $ 13,213 $ 9,366 Computer hardware 12,750 16,125 Furniture and office equipment 3,698 3,473 Leasehold improvements 8,330 3,166 Construction in process 94 426 38,085 32,556 Less: accumulated depreciation (21,389 ) (19,953 ) Total $ 16,696 $ 12,603 Depreciation expense for the years ended December 31, 2015 , 2014 and 2013 was $7.9 million , $5.7 million and $3.1 million , respectively. During the year ended December 31, 2015 , the Company recorded $0.7 million of accelerated depreciation expense as a result of relocating the Company's corporate headquarters to a new facility.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The following table shows the changes in the carrying amount of goodwill for the year ended December 31, 2015 (in thousands): Balance as of January 1, 2015 $ 21,518 Adjustments related to the E-Tale acquisition 114 Balance as of December 31, 2015 $ 21,632 Intangible assets consisted of the following (in thousands): December 31, 2015 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Weighted Average Useful Life (in years) Customer relationships $ 2,100 $ (350 ) $ 1,750 7.0 Acquired technology 1,700 (283 ) 1,417 7.0 Trade names 130 (51 ) 79 3.0 Total $ 3,930 $ (684 ) $ 3,246 6.9 December 31, 2014 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Weighted Average Useful Life (in years) Customer relationships $ 4,550 $ (2,312 ) $ 2,238 7.5 Acquired technology 1,700 (40 ) 1,660 7.0 Trade names 130 (7 ) 123 3.0 Proprietary software 710 (648 ) 62 8.0 Total $ 7,090 $ (3,007 ) $ 4,083 7.4 Amortization expense for the years ended December 31, 2015 , 2014 and 2013 was $0.9 million , $0.5 million and $0.6 million , respectively. As of December 31, 2015 , expected amortization expense over the remaining intangible asset lives is as follows (in thousands): 2016 $ 586 2017 579 2018 543 2019 543 2020 543 Thereafter 452 Total $ 3,246

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating and Capital Lease Commitments The Company leases office facilities and certain equipment under non-cancelable operating and capital leases. Future minimum lease payments on capital leases and future payments on operating leases with remaining terms in excess of one year are as follows (in thousands): Operating Leases Capital Leases Year Ending December 31, 2016 $ 6,337 $ 2,332 2017 5,489 1,882 2018 5,197 223 2019 4,135 — 2020 4,711 — Thereafter 10,008 — Total minimum lease payments $ 35,877 4,437 Less: imputed interest (207 ) Less: current portion (2,199 ) Capital lease obligations, net of current portion $ 2,031 The gross book value of fixed assets under capital leases as of December 31, 2015 and 2014 was approximately $7.9 million and $6.6 million , respectively. The net book value of fixed assets under capital leases as of December 31, 2015 and 2014 was approximately $4.1 million and $3.3 million , respectively. Capital lease obligations are included in other current liabilities and long-term capital leases in the accompanying consolidated balance sheets. The amortization of fixed assets under capital leases is included in depreciation expense within cost of goods sold and operating expenses in the accompanying consolidated statements of operations. Future minimum lease payments due under the non-cancelable operating lease arrangements contain fixed rent increases over the term of the lease. Rent expense on these operating leases is recognized over the term of the lease on a straight-line basis. The excess of rent expense over future minimum lease payments due has been reported in other current liabilities and other long-term liabilities in the accompanying consolidated balance sheets. As of December 31, 2015 and 2014 , deferred rent related to these leases totaled $1.1 million and $2.3 million , respectively. In August 2014, the Company entered into a lease agreement for the lease of office space to relocate the Company's corporate headquarters. The initial term of the lease agreement, which commenced in October 2015, is for seven years following the lease commencement date, and the Company may elect to renew the lease term for two additional five -year periods, subject to certain conditions and notice obligations set forth in the lease agreement. Minimum annual rental payments are $3.2 million the first lease year, and are scheduled to increase each lease year by 2.75% . Beginning January 1, 2017, the Company will also be obligated to pay its proportionate share of the landlord's operating expenses for the building, subject to certain limitations. In December 2015, the Company exercised its right to terminate the lease for its previous corporate headquarters effective as of October 1, 2016. In conjunction with the exercise of its early termination right, the Company paid approximately $1.0 million during the fourth quarter of 2015. Total rent expense for the years ended December 31, 2015 , 2014 and 2013 was $3.1 million , $3.4 million and $1.8 million , respectively. Guarantee In June 2014, the Company assigned its previous lease of office space in London, England to a third party pursuant to an assignment agreement and a transfer agreement. In accordance with the assignment agreement, the Company is not required to collect any payments from the third party and therefore will not recognize any revenue associated with this assignment. All payments associated with the assigned lease will be made directly by the third party to the lessor and appropriate regulatory authorities. However, the Company has guaranteed the lease payments through the remainder of the lease term, which is until February 2022. As of December 31, 2015 , the remaining lease payments under this lease totaled £2.1 million ( $3.1 million based on the exchange rate as of December 31, 2015 ). This amount represents the maximum potential liability for future payments under the guarantee and will decrease over time as payments are made by the third party. In the event of default, the indemnity clauses in the transfer agreement govern the Company's ability to pursue and recover damages incurred. During the year ended December 31, 2014 , the Company recorded a loss of $0.1 million associated with the assigned lease, which has been accounted for as a lease termination. As of December 31, 2015 , the Company does not anticipate any default by the third party. Therefore, no liability associated with this transaction has been recorded on the Company's consolidated balance sheet as of December 31, 2015 . Litigation and Other Contingencies In re ChannelAdvisor Securities Litigation . On January 23, 2015, plaintiff Justin Dice filed a purported class action complaint in the U.S. District Court for the Southern District of New York (S.D.N.Y.), Dice v. ChannelAdvisor Corporation et al., alleging violations of the federal securities laws against us and certain of the Company's executive officers. Plaintiff Dice alleges that the defendants engaged in a fraudulent scheme to artificially inflate the price of the Company's common stock by making false and misleading statements to investors concerning the Company's financial guidance for the fourth quarter of 2014. On January 26, 2015, plaintiff David Gracia also filed a purported class action complaint in the S.D.N.Y., Gracia v. ChannelAdvisor Corporation et al., in which Plaintiff Gracia brings the same claims, against the same named defendants, as in the action brought by Plaintiff Dice. On May 5, 2015, the S.D.N.Y. consolidated the Dice and Gracia actions, captioned the actions as In re ChannelAdvisor Securities Litigation , and appointed Plaintiff Dice as lead plaintiff for the putative class. On July 2, 2015, the S.D.N.Y. granted the defendants’ motion to transfer the case to the U.S. District Court for the Eastern District of North Carolina. On September 28, 2015, the defendants moved to dismiss the case and the outcome of the motion is pending. In addition, from time to time, the Company is subject to litigation and claims arising in the ordinary course of business but except as stated above, it is not currently a party to any material legal proceedings and it is not aware of any pending or threatened legal proceeding against the Company that it believes could have a material adverse effect on its business, operating results, cash flows or financial condition. During the year ended December 31, 2015, the Company recorded a charge of $0.6 million pertaining to indirect taxes in certain jurisdictions. The Company has reviewed the applicable statutes in other jurisdictions in which it may have tax nexus and has concluded that no amounts are owed to these jurisdictions at this time. The Company estimates that, if it had been subject to indirect tax in such jurisdictions, the amounts owed could approximate up to $3.9 million . Such amount does not consider, if necessary, any remedies including those which may be offered by these jurisdictions.

Debt

Debt	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt	Debt In December 2009, the Company entered into a loan and security agreement (the “Loan and Security Agreement”) with a lender. The Loan and Security Agreement has been amended several times, most recently on September 17, 2014. The Loan and Security Agreement includes a revolving line of aggregate advances (the “Revolving Line of Credit”) totaling $10.0 million . The Revolving Line of Credit has a term through September 17, 2016 and requires interest-only payments to be made monthly on any outstanding advances during the term at the lender’s prime rate, which was 3.50% at December 31, 2015 , plus 0.25% . The Company is also obligated to pay an unused facility fee in the amount of 0.15% per year on any unused borrowing capacity. The Revolving Line of Credit is collateralized by all of the Company's assets, excluding its intellectual property, although the Company may not encumber its intellectual property without the consent of the bank. Under the terms of the Loan and Security Agreement, the Company is required to meet and maintain certain monthly and annual financial and nonfinancial covenants. As of December 31, 2015 , the Company was in compliance with all such covenants. As of December 31, 2015 and 2014 , the Company had no amounts outstanding under the Loan and Security Agreement. In March 2012, the Company signed a loan and security agreement (the "Subordinated Loan Agreement") with a subordinated lender, which was amended in October 2013. Borrowings under the Subordinated Loan Agreement accrued interest at an annual rate of 10.5% . During 2012, the Company borrowed $10.0 million under this Subordinated Loan Agreement. In November 2013, the Company entered into a payoff agreement with the lender pursuant to which the Company paid all amounts due and owing under the Subordinated Loan Agreement and terminated the Subordinated Loan Agreement. Under the payoff agreement, the Company paid the lender approximately $11.3 million , of which $1.2 million represented a fixed prepayment fee and other extinguishment costs. In connection with this prepayment, the Company recognized a pre-tax loss on extinguishment of debt of $3.1 million during year ended December 31, 2013, representing the difference between the par value and payoff amount of the loan, increased by the write-off of unamortized debt issuance costs and accelerated amortization of the remaining debt discount.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of income (loss) before income taxes for the years ended December 31, 2015 , 2014 and 2013 were as follows (in thousands): 2015 2014 2013 Domestic $ (21,146 ) $ (36,053 ) $ (7,222 ) Foreign 10 1,580 (13,203 ) Total loss before income taxes $ (21,136 ) $ (34,473 ) $ (20,425 ) The provision for income tax expense (benefit) included the following for the years ended December 31, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Current: Federal $ — $ — $ 22 State (101 ) 11 193 Foreign 160 8 — Total 59 19 215 Deferred: Federal 37 42 (26 ) State 15 5 14 Foreign (296 ) (25 ) — Total (244 ) 22 (12 ) Total tax (benefit) expense $ (185 ) $ 41 $ 203 Deferred income taxes reflect the net tax effect of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The components of the Company’s net deferred tax assets (liabilities) as of December 31, 2015 , 2014 and 2013 were as follows (in thousands): 2015 2014 2013 Current: Deferred tax assets: Other assets $ 2,133 $ 1,615 $ 832 Valuation allowance (1,877 ) (1,562 ) (726 ) Total deferred tax assets 256 53 106 Deferred tax liabilities: Other liabilities (58 ) (57 ) (71 ) Net deferred tax (liability) asset, current $ 198 $ (4 ) $ 35 Noncurrent: Deferred tax assets: Domestic tax loss carryforwards $ 31,573 $ 28,822 $ 18,898 Foreign tax loss carryforwards 5,678 6,695 7,673 Stock-based compensation 3,375 2,546 — Tax credits 1,178 658 78 Other assets 2,214 811 866 Valuation allowance (42,156 ) (38,700 ) (26,206 ) Total deferred tax assets 1,862 832 1,309 Deferred tax liabilities: Fixed assets 2,146 622 1,149 Intangible assets 589 1,184 — Other liabilities 57 — 383 Total deferred tax liabilities 2,792 1,806 1,532 Net deferred tax liability, noncurrent $ (930 ) $ (974 ) $ (223 ) At December 31, 2015 , 2014 and 2013 , the Company had federal gross operating loss carryforwards of $106.4 million , $99.3 million and $62.5 million , respectively, which expire beginning in 2022. At December 31, 2015 , 2014 and 2013 , the Company had state net operating loss ("NOL") carryforwards of $117.0 million , $104.2 million and $55.2 million , respectively, which expire beginning in 2018. The Company’s federal and state net operating losses include $21.5 million of excess tax benefits related to deductions from the exercise of nonqualified stock options. The tax benefit of these deductions has not been recognized in deferred tax assets. If utilized, the benefits from these deductions will be recorded as adjustments to taxes payable and additional paid-in-capital. At December 31, 2015 , 2014 and 2013 , the Company had U.S. federal income tax credit carryforwards of $1.6 million , $0.8 million and $0.1 million , respectively, which expire beginning in 2034. The utilization of the net operating loss and tax credit carryforwards may be subject to limitation under the rules regarding a change in stock ownership as determined by the Internal Revenue Code and state and foreign tax laws. The Company is in the process of assessing any limitations, particularly related to net operating loss carryforwards from its acquired entities. At December 31, 2015 , 2014 and 2013 , the Company also had foreign NOL carryforwards for use against future tax in those jurisdictions of $27.3 million , $30.9 million and $25.1 million , respectively. The majority of the Company's foreign net operating losses can be carried forward indefinitely. A valuation allowance has been recognized to offset the deferred tax assets related to all NOL carryforwards. The total increase in valuation allowance of $3.8 million during the year ended December 31, 2015 was allocable to current operating activities. Two exceptions to the valuation allowance analysis are the deferred tax liability associated with an indefinite-lived intangible asset and the U.S. federal alternative minimum tax credit carryforward. The deferred tax liability associated with the indefinite-lived intangible asset cannot be used to support other deferred tax assets in arriving at the valuation allowance to be recorded. Since both the deferred tax liability and the deferred tax asset have indefinite lives, they offset each other to arrive at the net deferred tax liability. Undistributed earnings of the Company’s foreign subsidiaries are indefinitely reinvested offshore and, accordingly, no provision for U.S. federal or state income taxes has been provided thereon. The cumulative amount of undistributed earnings of the Company’s non-U.S. subsidiaries was approximately $0.8 million for each of the years ended December 31, 2014 and 2013 . The cumulative amount of undistributed earnings of the Company’s non-U.S. subsidiaries for the year ended December 31, 2015 was nominal. The determination of the deferred tax liability, which requires complex analysis of international tax situations related to repatriation, is not practicable at this time. The Company is presently investing in international operations located in Europe, Asia, Australia and South America. The Company is funding the working capital needs of its foreign operations through its U.S. operations. In the future, the Company will utilize its foreign undistributed earnings, as well as continued funding from its U.S. operations, to support its continued foreign investment. A reconciliation of the difference between the effective income tax rate and the statutory federal income tax rate for the years ended December 31, 2015 , 2014 and 2013 is as follows: 2015 2014 2013 U.S. statutory federal rate 34.0 % 34.0 % 34.0 % Increase (decrease) resulting from: State taxes, net of federal benefit 4.3 4.8 1.6 Nondeductible expenses (14.0 ) (0.1 ) (5.2 ) Effect of foreign tax rate differential (0.1 ) 0.6 (8.0 ) Uncertain tax position (1.5 ) (0.4 ) — Research and development credit 3.7 2.1 — Change in valuation allowance (20.3 ) (39.7 ) (22.4 ) Other (5.2 ) (1.4 ) (1.0 ) Effective tax rate 0.9 % (0.1 )% (1.0 )% The nondeductible expenses during the year ended December 31, 2015 primarily related to stock compensation expense associated with incentive stock options and share-based compensation shortfalls. Effective January 1, 2009, the Company adopted Accounting Standards Codification Topic 740-10, Income Taxes ("ASC 740-10") associated with accounting for uncertainty in income taxes. These provisions provide a comprehensive model for the recognition, measurement and disclosure in financial statements of uncertain income tax positions that a company has taken or expects to take on a tax return. The following table shows the changes in unrecognized tax benefits in accordance with ASC 740-10 for the years ended December 31, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Balance as of January 1, $ 782 $ — $ — Increases related to current tax positions 345 149 — Increases related to prior year tax positions 79 697 — Decreases related to prior year tax positions (411 ) (64 ) — Decreases related to the expirations of statutes of limitations (114 ) — — Balance as of December 31, $ 681 $ 782 $ — Although the ultimate timing of the resolution and/or closure of audits is highly uncertain, the Company believes it is reasonably possible that a de minimis amount of unrecognized tax benefits could reverse in the next twelve months. If the total unrecognized tax benefit was recognized, there would be a de minimis impact on the effective tax rate. As of December 31, 2015 and 2014 , the Company had no accrued interest or penalties related to the tax contingencies. The Company’s policy for recording interest and penalties is to record them as a component of provision for income taxes. The Company has analyzed its filing positions in all significant federal, state and foreign jurisdictions where it is required to file income tax returns, as well as open tax years in these jurisdictions. With few exceptions, the Company is no longer subject to U.S. federal and state and local tax examinations by tax authorities for years prior to 2011, although carryforward attributes that were generated prior to 2011 may still be adjusted upon examination by the Internal Revenue Service if they either have been or will be used in a future period. The Company is no longer subject to examination in foreign tax jurisdictions for tax periods 2011 and prior. No income tax returns are currently under examination by taxing authorities.

Warrants

Warrants	12 Months Ended
	Dec. 31, 2015
Other Liabilities Disclosure [Abstract]
Warrants	Warrants In 2007 and 2008, the Company issued warrants to purchase 1,616,113 shares of common stock, of which 958,019 and 658,094 have exercise prices per share of $16.00 and $10.96 , respectively. The 2007 warrants expired in 2014 and the 2008 warrants expired in 2015 . During 2013, the holders of certain of these warrants to purchase common stock executed exercises and received 662,362 shares of common stock in exchange for the warrants. During 2014, the holders of certain of these warrants to purchase common stock executed exercises and received 664,058 shares of common stock in exchange for the warrants.

Equity Incentive Plan and Stock

Equity Incentive Plan and Stock-Based Compensation	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Incentive Plans and Stock-Based Compensation	Equity Incentive Plans and Stock-Based Compensation In May 2013, the Company’s board of directors adopted, and the Company’s stockholders approved, the 2013 Equity Incentive Plan (the “2013 Plan”), pursuant to which the Company initially reserved 1,250,000 shares of its common stock for issuance to its employees, directors and non-employee third parties. The 2013 Plan provides for the grant of incentive stock options to employees, and for the grant of nonqualified stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance stock awards and other forms of stock compensation to the Company’s employees, directors, and non-employee third parties. The number of shares of common stock reserved for issuance under the 2013 Plan will automatically increase on January 1 each year, for a period of ten years, from January 1, 2014 through January 1, 2023, by 5% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors. Accordingly, on January 1, 2016 the number of shares reserved for issuance under the 2013 Plan increased by 1,261,547 shares. As of December 31, 2015 , 1,064,122 shares remained available for future grant under the 2013 Plan. As a result of the adoption of the 2013 Plan, no further grants may be made under the former 2001 Stock Plan, although outstanding awards under the 2001 Stock Plan continue to vest in accordance with their terms until exercised, forfeited or expired. Stock-based compensation expense related to stock options is included in the following line items in the accompanying consolidated statements of operations for the years ended December 31, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Cost of revenue $ 992 $ 533 $ 204 Sales and marketing 4,349 2,911 607 Research and development 1,689 864 348 General and administrative 4,807 3,673 940 $ 11,837 $ 7,981 $ 2,099 Stock Option Awards The Company values stock options using the Black-Scholes option-pricing model, which requires the input of subjective assumptions, including the risk-free interest rate, expected life, expected stock price volatility and dividend yield. The risk-free interest rate assumption is based upon observed interest rates for constant maturity U.S. Treasury securities consistent with the expected term of the Company’s employee stock options. The expected life represents the period of time the stock options are expected to be outstanding and is based on the “simplified method.” Under the “simplified method,” the expected life of an option is presumed to be the mid-point between the vesting date and the end of the contractual term. The Company used the “simplified method” due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to otherwise estimate the expected life of the stock options. Expected volatility is based on historical volatilities for publicly traded stock of comparable companies over the estimated expected life of the stock options. The Company assumed no dividend yield because dividends are not expected to be paid in the near future, which is consistent with the Company’s history of not paying dividends. The following table summarizes the assumptions used for estimating the fair value of stock options granted for the years ended December 31, 2015 , 2014 and 2013 : 2015 2014 2013 Risk-free interest rate 0.9% - 1.7% 0.3% - 2.0% 0.3% - 1.7% Expected term (years) 6.25 6.06 - 6.25 5.00 - 6.25 Expected volatility 45% - 47% 43% - 56% 43% - 59% Dividend yield 0% 0% 0% The following is a summary of the option activity for the year ended December 31, 2015 : Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in years) (in thousands) Outstanding balance at January 1, 2015 1,425,357 $ 9.12 Granted 456,871 10.59 Exercised (169,879 ) 5.39 Forfeited (200,511 ) 14.78 Expired (41,545 ) 25.06 Outstanding balance at December 31, 2015 1,470,293 $ 8.79 7.22 $ 8,899 Exercisable at December 31, 2015 877,515 $ 7.00 6.16 $ 6,824 Vested and expected to vest at December 31, 2015 1,379,819 $ 8.61 7.12 $ 8,577 The weighted average grant date fair value for the Company's stock options granted during the years ended December 31, 2015 , 2014 , and 2013 was $4.29 , $13.88 and $5.29 per share, respectively. The total fair value of stock options vested during the years ended December 31, 2015 , 2014 and 2013 was $1.2 million , $1.5 million and $0.9 million , respectively. The total compensation cost related to nonvested stock options not yet recognized as of December 31, 2015 was $1.2 million and will be recognized over a weighted average period of approximately 1.9 years. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2015 , 2014 , and 2013 was $1.2 million , $16.0 million and $17.6 million , respectively. Restricted Stock Units The following table summarizes the RSU activity for the year ended December 31, 2015 : Number of RSUs Weighted Average Grant-Date Fair Value Unvested RSUs as of January 1, 2015 944,734 $ 22.77 Granted 1,559,823 10.23 Vested (222,895 ) 24.78 Forfeited (331,960 ) 14.85 Unvested RSUs as of December 31, 2015 1,949,702 $ 13.85 The total unrecognized compensation cost related to the unvested RSUs as of December 31, 2015 was $11.6 million and will be recognized over a weighted average period of approximately 1.8 years.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share The following securities have been excluded from the calculation of weighted average common shares outstanding because the effect is anti-dilutive for the years ended December 31, 2015 , 2014 and 2013 : 2015 2014 2013 Warrants to purchase common stock — 3,743 986,784 Stock options 1,470,293 1,425,357 2,068,641 RSUs 1,949,702 944,734 —

Segment and Geographic Informat

Segment and Geographic Information	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Segment and Geographic Information	Segment and Geographic Information Operating segments are defined as components of an enterprise for which discrete financial information is available that is evaluated regularly by the chief operating decision maker (“CODM”) for purposes of allocating resources and evaluating financial performance. The Company’s CODM reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. As such, the Company’s operations constitute a single operating segment and one reportable segment. Substantially all assets were held in the United States during the years ended December 31, 2015 and 2014 . The following table summarizes revenue by geography for the years ended December 31, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Revenue: Domestic $ 77,785 $ 65,750 $ 53,832 International 22,800 19,151 14,172 Total $ 100,585 $ 84,901 $ 68,004 The Company's revenue from external customers based in the United Kingdom totaled approximately $13.6 million , $11.4 million and $8.9 million for the years ended December 31, 2015 , 2014 and 2013 , respectively.

Retirement Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Retirement Plan	Retirement Plans The Company provides retirement plans whereby participants may elect to contribute a portion of their annual compensation to the plans, after complying with certain requirements and subject to certain limitations. The Company contributed an aggregate of $0.8 million to the plans for each of the years ended December 31, 2015 and 2014 and $0.5 million for the year ended December 31, 2013 .

Selected Quarterly Information

Selected Quarterly Information	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Information (unaudited)	Selected Quarterly Information (unaudited) Three Months Ended, March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenue $ 22,590 $ 24,182 $ 24,379 $ 29,434 Gross profit 16,174 17,781 18,089 22,707 Loss from operations (9,056 ) (6,595 ) (4,744 ) (798 ) Net loss (8,956 ) (6,524 ) (4,791 ) (680 ) Net loss per share: Basic and diluted (0.36 ) (0.26 ) (0.19 ) (0.03 ) Three Months Ended, March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenue $ 19,338 $ 20,770 $ 20,966 $ 23,827 Gross profit 13,606 14,351 14,948 17,776 Loss from operations (9,280 ) (9,511 ) (8,857 ) (6,360 ) Net loss (9,370 ) (9,604 ) (9,004 ) (6,536 ) Net loss per share: Basic and diluted (0.39 ) (0.39 ) (0.36 ) (0.26 )

Significant Accounting Polici22

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.
Reclassification	Reclassification Certain prior period amounts included on the condensed consolidated statements of operations have been reclassified to conform to the current period’s presentation. In order to gain further clarity and understanding of its operating results, the Company will now present depreciation and amortization expense separately on the condensed consolidated statements of operations. Previously, depreciation and amortization expense was included in cost of revenue and operating expenses. These reclassifications had no effect on the Company's reported gross profit and net loss for the years ended December 31, 2014 and 2013 . The tables below summarize these reclassifications (in thousands): Year Ended December 31, 2014 As Previously Reported Reclassification As Reclassified Cost of revenue (excluding depreciation) $ 24,220 $ (3,507 ) $ 20,713 Depreciation - Cost of revenue — 3,507 3,507 Sales and marketing 55,829 (927 ) 54,902 Research and development 16,585 (370 ) 16,215 General and administrative 22,275 (1,460 ) 20,815 Depreciation and amortization — 2,757 2,757 Year Ended December 31, 2013 As Previously Reported Reclassification As Reclassified Cost of revenue (excluding depreciation) $ 18,088 $ (2,141 ) $ 15,947 Depreciation - Cost of revenue — 2,141 2,141 Sales and marketing 37,458 (516 ) 36,942 Research and development 12,669 (243 ) 12,426 General and administrative 14,154 (822 ) 13,332 Depreciation and amortization — 1,581 1,581
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"), which provides new guidance for revenue recognition. ASU 2014-09 provides that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 also requires improved disclosures to help users of financial statements better understand the nature, amount, timing, and uncertainty of revenue that is recognized. Entities have the option of using either a full retrospective or modified retrospective approach for the adoption of the standard. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date , which resulted in a one year deferral of the effective date of ASU 2014-09 to annual reporting periods beginning after December 15, 2017. Early adoption is permitted for annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. The Company is currently evaluating the impact the adoption of ASU 2014-09 will have on its consolidated financial statements. In September 2015, the FASB issued ASU No. 2015-16, Simplifying the Accounting for Measurement-Period Adjustments (Topic 805) ("ASU 2015-16"), which eliminates the requirement that an acquirer in a business combination account for measurement-period adjustments retrospectively. ASU 2015-16 requires that the cumulative impact of measurement-period adjustments, including prior period amounts, be recognized in the reporting period in which the adjustment is identified. The update is effective for fiscal years beginning after December 15, 2015. The Company has elected to early adopt ASU 2015-16; however, the adoption of this pronouncement did not have a material impact on the Company’s results of operations, financial position or cash flows. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes (Topic 740) ("ASU 2015-17"), which requires that all deferred tax assets and liabilities, including any related valuation allowance, be classified as noncurrent on the balance sheet. The update is effective for fiscal years beginning after December 15, 2016 and early adoption is permitted. The guidance may be applied either prospectively or retrospectively. The Company is currently evaluating the impact the adoption of ASU 2015-17 will have on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"), which requires that lessees recognize assets and liabilities for leases with lease terms greater than twelve months in the statement of financial position. ASU 2016-02 also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. The update is effective for fiscal years beginning after December 15, 2018, including interim reporting periods within that reporting period. Early adoption is permitted. The Company is currently evaluating the impact the adoption of ASU 2016-02 will have on its consolidated financial statements. The Company has reviewed other new accounting pronouncements that were issued as of December 31, 2015 and does not believe that these pronouncements are applicable to the Company, or that they will have a material impact on its financial position or results of operations.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with United States generally accepted accounting principles (“U.S. GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those related to the accounts receivable allowance, the useful lives of long-lived assets and other intangible assets, income taxes and assumptions used for purposes of determining stock-based compensation, among others. Estimates and assumptions are also required to value assets acquired and liabilities assumed as well as contingent consideration, where applicable, in conjunction with business combinations. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable, the results of which form the basis for making judgments about the carrying value of assets and liabilities.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments maturing within ninety days or less at the time of purchase to be cash equivalents. Cash and cash equivalents are comprised of cash and money market funds. Due to the short-term nature and liquidity of these financial instruments, the carrying value of these assets approximates fair value.
Restricted Cash	Restricted Cash Restricted cash represents cash that is not readily available for general purpose cash needs.
Revenue Recognition and Deferred Revenue	Revenue Recognition and Deferred Revenue The majority of the Company’s revenue is derived from subscription fees paid by customers for access to and usage of the Company’s cloud-based SaaS platform for a specified period of time, which is typically one year. A portion of the subscription fee is typically fixed and is based on a specified minimum amount of gross merchandise value (“GMV”) that a customer expects to process through the Company’s platform over the contract term. The remaining portion of the subscription fee is variable and is based on a specified percentage of GMV processed through the Company’s platform in excess of the customer’s specified minimum amount. In addition, other sources of revenue consist primarily of implementation fees, which may include fees for providing launch assistance and training. Implementation services are provided at the customer's option and are not essential to the functionality of the Company's platform, nor is the customer required to purchase these services in order to access the Company's platform. The Company also generates revenue from its solutions that allow branded manufacturers to direct potential consumers from their websites and digital marketing campaigns to authorized resellers. These contacts are generally one year in duration. The Company recognizes revenue when there is persuasive evidence of an arrangement, the service has been provided to the customer, the collection of the fee is reasonably assured and the amount of the fee to be paid by the customer is fixed or determinable. The Company’s contractual arrangements include performance, termination and cancellation provisions, but do not provide for refunds. Customers do not have the contractual right to take possession of the Company’s software at any time. The Company’s arrangements generally contain multiple elements comprised of subscription and implementation services. The Company evaluates each element in an arrangement to determine whether it represents a separate unit of accounting. An element constitutes a separate unit of accounting when the delivered item has standalone value and delivery of the undelivered element is probable and within the Company’s control. The Company’s implementation services are not sold separately from the subscription and there is no alternative use for them. As such, the Company has determined the implementation services do not have standalone value. Accordingly, subscription and implementation services are combined and recognized as a single unit of accounting. The Company generally recognizes the fixed portion of subscription fees and implementation fees ratably over the contract term. Recognition begins when the customer has access to the Company’s platform or to its solutions for branded manufacturers and transactions can be processed, provided all other revenue recognition criteria have been met. Some customers elect a managed-service solution and contract with the Company to manage some or all aspects of the Company’s SaaS solutions on the customer’s behalf for a specified period of time, which is typically one year. Under these managed-service arrangements, customer transactions cannot be processed through the Company’s platform until the completion of the implementation services. As such, revenue is contingent upon the Company’s completion of the implementation services and recognition commences when transactions can be processed on the Company’s platform, provided all other revenue recognition criteria have been satisfied. At that time, the Company recognizes a pro-rata portion of the fees earned since the inception of the arrangement. The balance of the fees is recognized ratably over the remaining contract term. The Company recognizes the variable portion of subscription fee revenue in the period in which the related GMV is processed, provided all other revenue recognition criteria have been met. Sales taxes collected from customers and remitted to government authorities are excluded from revenue. Deferred revenue represents the unearned portion of fixed subscription fees and implementation fees. Deferred amounts are generally recognized within one year. Those amounts that are expected to be recognized in greater than one year are recorded in other long-term liabilities in the accompanying condensed consolidated balance sheets.
Sales Commissions	Sales Commissions Sales commissions are expensed when the related subscription agreement is executed by the customer.
Cost of Revenue	Cost of Revenue Cost of revenue primarily consists of personnel and related costs, including salaries, bonuses, payroll taxes and stock-based compensation, co-location facility costs for the Company’s data centers, depreciation expense for computer equipment directly associated with generating revenue, credit card transaction fees and infrastructure maintenance costs. In addition, the Company allocates a portion of overhead, such as rent, additional depreciation and amortization and employee benefits costs, to cost of revenue based on headcount.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company uses a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires the Company to use observable inputs when available, and to minimize the use of unobservable inputs when determining fair value. The three tiers are defined as follows: • Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities; • Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and • Level 3. Unobservable inputs for which there is little or no market data, which require the Company to develop its own assumptions. The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate their respective fair values due to their short-term nature. The acquisition of E-Tale includes a contingent consideration arrangement that allows for adjustment of payments based upon achievement of specified quarterly revenue targets through June 2017. Contingent consideration was measured at fair value at the acquisition date and is remeasured to fair value at each reporting date until the contingency is resolved. The fair value is reported within other current liabilities and other long-term liabilities on the consolidated balance sheets. Increases or decreases in any valuation inputs in isolation may result in a significantly lower or higher fair value measurement in the future. Subsequent changes in the fair value of contingent consideration are recognized within general and administrative expenses in the Company’s consolidated statements of operations. The fair value of contingent consideration related to the E-Tale acquisition is based on projected quarterly revenue targets for E-Tale through June 2017. The Company discounted the expected future earn-out payment to net present value using Level 3 inputs. A key assumption used in the measurement of fair value of contingent consideration includes a discount rate of 22% and 24% as of December 31, 2015 and 2014 , respectively. The Company believes the discount rate used to discount the earn-out payments reflects market participant assumptions. Projected revenue is based on the Company’s internal projections and analysis of the current customer base and expected customer growth, target market and sales potential.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. All of the Company’s cash and cash equivalents are held at financial institutions that management believes to be of high credit quality. The Company’s cash and cash equivalents accounts exceed federally insured limits. The Company has not experienced any losses on its cash and cash equivalents accounts to date. To manage accounts receivable risk, the Company maintains an allowance for doubtful accounts.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts The Company extends credit to customers without requiring collateral. Accounts receivable are stated at realizable value, net of an allowance for doubtful accounts. The Company utilizes the allowance method to provide for doubtful accounts based on management’s evaluation of the collectability of amounts due. The Company’s estimate is based on historical collection experience and a review of the current status of accounts receivable. Historically, actual write-offs for uncollectible accounts have not significantly differed from the Company’s estimates.
Other Receivables	Other Receivables Under certain customer arrangements, the Company collects and remits monthly activity-based fees incurred on specific channels on the customers’ behalf. The Company records the amounts due from customers as a result of these arrangements as other receivables.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost. Expenditures for major additions and improvements are capitalized. Depreciation and amortization is provided over the estimated useful lives of the related assets using the straight-line method. The estimated useful lives for significant property and equipment categories are generally as follows: Purchased software, including internal-use software 3 years Computer hardware 3 years Furniture and office equipment 3 to 5 years Leasehold improvements Lesser of remaining lease term or useful life Repairs and maintenance costs are expensed as incurred.
Identifiable Intangible Assets	Identifiable Intangible Assets The Company acquired intangible assets in connection with its business acquisitions. See Note 3 included in this Annual Report for information regarding intangible assets acquired in connection with the acquisition of E-Tale. These assets were recorded at their estimated fair values at the acquisition date and are being amortized over their respective estimated useful lives using the straight-line method. The estimated useful lives and amortization methodology used in computing amortization are as follows: Estimated Useful Lives Amortization Methodology Customer relationships 7 years Straight-line Acquired technology 7 years Straight-line Trade names 3 years Straight-line
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews long-lived assets and definite-lived intangible assets for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. Recoverability of the long-lived asset is measured by a comparison of the carrying amount of the asset or asset group to future undiscounted net cash flows expected to be generated by the asset or asset group. If such assets are not recoverable, the impairment to be recognized, if any, is measured by the amount by which the carrying amount of the assets exceeds the estimated fair value of the assets or asset group. Assets held for sale are reported at the lower of the carrying amount or fair value, less costs to sell.
Goodwill	Goodwill Goodwill represents the excess of the aggregate of the fair value of consideration transferred in a business combination over the fair value of assets acquired, net of liabilities assumed. The Company recorded goodwill in connection with its business acquisitions. See Note 3 and Note 5 below for information regarding goodwill recorded in connection with the acquisition of E-Tale. Goodwill is not amortized, but is subject to an annual impairment test. The Company tests goodwill for impairment annually on December 31, or more frequently if events or changes in business circumstances indicate the asset might be impaired. The Company has determined that it has a single, entity-wide reporting unit. The Company first assessed qualitative factors to determine whether it was more likely than not that the fair value of its single reporting unit was less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test under ASU No. 2011-08, Goodwill and Other (Topic 350): Testing Goodwill for Impairment. If the qualitative factors had indicated that it was more likely than not that the fair value of the reporting unit was less than its carrying amount, the Company would have tested goodwill for impairment at the reporting unit level using a two-step approach. The first step is to compare the fair value of the reporting unit to the carrying value of the net assets assigned to the reporting unit. If the fair value of the reporting unit is greater than the carrying value of the net assets assigned to the reporting unit, the assigned goodwill is not considered impaired. If the fair value is less than the reporting unit’s carrying value, step two is performed to measure the amount of the impairment, if any. In the second step, the fair value of goodwill is determined by deducting the fair value of the reporting unit’s identifiable assets and liabilities from the fair value of the reporting unit as a whole, as if the reporting unit had just been acquired and the fair value was being initially allocated. If the carrying value of goodwill exceeds the implied fair value, an impairment charge would be recorded in the period the determination is made.
Advertising Costs	Advertising Costs The Company expenses advertising costs as incurred.
Software Development Costs	Software Development Costs The Company capitalizes certain internal-use software development costs, consisting primarily of direct labor associated with creating the internally developed software and third-party consulting fees associated with implementing software purchased for internal use. Software development projects generally include three stages: the preliminary project stage (in which all costs are expensed as incurred), the application development stage (in which certain costs are capitalized) and the post-implementation/operation stage (in which all costs are expensed as incurred). The costs incurred during the application development stage primarily include the costs of designing the application, coding and testing of the system. Capitalized costs are amortized using the straight-line method over the estimated useful life of the software once it is ready for its intended use.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method of accounting. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, as well as for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the results of operations in the period that includes the enactment date. The measurement of a deferred tax asset is reduced, if necessary, by a valuation allowance if it is more likely than not that some portion or all of the deferred tax asset will not be realized. The Company applies the accounting guidance for uncertainties in income taxes, which prescribes a recognition threshold and measurement process for recording uncertain tax positions taken, or expected to be taken, in a tax return in the financial statements. Additionally, the guidance also prescribes the treatment for the derecognition, classification, accounting in interim periods and disclosure requirements for uncertain tax positions. The Company accrues for the estimated amount of taxes for uncertain tax positions if it is more likely than not that the Company would be required to pay such additional taxes. An uncertain tax position will be recognized if it is more likely than not to be sustained. The Company’s policy for recording interest and penalties is to record them as a component of provision for income taxes.
Foreign Currency Translation	Foreign Currency Translation The functional currency of the Company’s non-U.S. operations is the local currency. Monetary assets and liabilities denominated in foreign currencies are translated into U.S. dollars at exchange rates prevailing at the balance sheet dates. Non-monetary assets and liabilities are translated at the historical rates in effect when the assets were acquired or obligations incurred. Revenue and expenses are translated into U.S. dollars using the average rates of exchange prevailing during the period. Gains or losses resulting from the translation of assets and liabilities are included as a component of accumulated other comprehensive loss in stockholders’ equity. Gains and losses resulting from foreign currency transactions are recognized as other (expense) income.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation awards, which include stock options and restricted stock units ("RSUs"), based on the fair value of the award as of the grant date. The Company recognizes stock-based compensation expense using the accelerated attribution method, net of estimated forfeitures, in which compensation cost for each vesting tranche in an award is recognized ratably from the service inception date to the vesting date for that tranche. The Company uses the Black-Scholes option pricing model for estimating the fair value of stock options. The use of the option valuation model requires the input of the Company's stock price, as well as highly subjective assumptions, including the expected life of the option and the expected stock price volatility based on peer companies. Additionally, the recognition of expense requires the estimation of the number of awards that will ultimately vest and the number of awards that will ultimately be forfeited. The fair value of the Company's common stock, for purposes of determining the grant date fair value of option and RSU awards, has been determined by using the closing market price per share of common stock as quoted on the New York Stock Exchange on the date of grant.
Basic and Diluted Loss per Common Share	Basic and Diluted Loss per Common Share Diluted loss per share is the same as basic loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive given the Company’s net loss.

Significant Accounting Polici23

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Schedule of Reclassifications	The tables below summarize these reclassifications (in thousands): Year Ended December 31, 2014 As Previously Reported Reclassification As Reclassified Cost of revenue (excluding depreciation) $ 24,220 $ (3,507 ) $ 20,713 Depreciation - Cost of revenue — 3,507 3,507 Sales and marketing 55,829 (927 ) 54,902 Research and development 16,585 (370 ) 16,215 General and administrative 22,275 (1,460 ) 20,815 Depreciation and amortization — 2,757 2,757 Year Ended December 31, 2013 As Previously Reported Reclassification As Reclassified Cost of revenue (excluding depreciation) $ 18,088 $ (2,141 ) $ 15,947 Depreciation - Cost of revenue — 2,141 2,141 Sales and marketing 37,458 (516 ) 36,942 Research and development 12,669 (243 ) 12,426 General and administrative 14,154 (822 ) 13,332 Depreciation and amortization — 1,581 1,581
Fair Value Level 3 Reconciliation	The following table presents changes to the Company's liability for acquisition-related contingent consideration for the year ended December 31, 2015 (in thousands): Balance, as of January 1, 2015 $ 618 Change in contingent consideration fair value 79 Balance, as of December 31, 2015 $ 697
Changes in Allowance for Doubtful Accounts	The following table presents the changes in the Company’s allowance for doubtful accounts during the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at Beginning of Period Additions Charged To Expense/ Against Revenue Deductions Balance at End of Period Allowance for doubtful accounts: Year ended December 31, 2015 $ 673 1,315 (1,203 ) $ 785 Year ended December 31, 2014 $ 561 737 (625 ) $ 673 Year ended December 31, 2013 $ 191 594 (224 ) $ 561
Schedule of Property and Equipment	The estimated useful lives for significant property and equipment categories are generally as follows: Purchased software, including internal-use software 3 years Computer hardware 3 years Furniture and office equipment 3 to 5 years Leasehold improvements Lesser of remaining lease term or useful life Property and equipment consisted of the following as of December 31, 2015 and 2014 (in thousands): 2015 2014 Purchased software, including internal-use software $ 13,213 $ 9,366 Computer hardware 12,750 16,125 Furniture and office equipment 3,698 3,473 Leasehold improvements 8,330 3,166 Construction in process 94 426 38,085 32,556 Less: accumulated depreciation (21,389 ) (19,953 ) Total $ 16,696 $ 12,603
Schedule of Intangible Assets	The estimated useful lives and amortization methodology used in computing amortization are as follows: Estimated Useful Lives Amortization Methodology Customer relationships 7 years Straight-line Acquired technology 7 years Straight-line Trade names 3 years Straight-line Intangible assets consisted of the following (in thousands): December 31, 2015 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Weighted Average Useful Life (in years) Customer relationships $ 2,100 $ (350 ) $ 1,750 7.0 Acquired technology 1,700 (283 ) 1,417 7.0 Trade names 130 (51 ) 79 3.0 Total $ 3,930 $ (684 ) $ 3,246 6.9 December 31, 2014 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Weighted Average Useful Life (in years) Customer relationships $ 4,550 $ (2,312 ) $ 2,238 7.5 Acquired technology 1,700 (40 ) 1,660 7.0 Trade names 130 (7 ) 123 3.0 Proprietary software 710 (648 ) 62 8.0 Total $ 7,090 $ (3,007 ) $ 4,083 7.4

Business Combination (Tables)

Business Combination (Tables)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The Company's allocation of the total purchase consideration is as follows (in thousands): Cash $ 124 Accounts receivable 506 Customer relationships 2,100 Acquired technology 1,700 Trade names 130 Deferred tax liability (794 ) Other assets/liabilities, net (334 ) Goodwill 5,526 Total purchase price $ 8,958

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	The estimated useful lives for significant property and equipment categories are generally as follows: Purchased software, including internal-use software 3 years Computer hardware 3 years Furniture and office equipment 3 to 5 years Leasehold improvements Lesser of remaining lease term or useful life Property and equipment consisted of the following as of December 31, 2015 and 2014 (in thousands): 2015 2014 Purchased software, including internal-use software $ 13,213 $ 9,366 Computer hardware 12,750 16,125 Furniture and office equipment 3,698 3,473 Leasehold improvements 8,330 3,166 Construction in process 94 426 38,085 32,556 Less: accumulated depreciation (21,389 ) (19,953 ) Total $ 16,696 $ 12,603

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table shows the changes in the carrying amount of goodwill for the year ended December 31, 2015 (in thousands): Balance as of January 1, 2015 $ 21,518 Adjustments related to the E-Tale acquisition 114 Balance as of December 31, 2015 $ 21,632
Schedule of Intangible Assets	The estimated useful lives and amortization methodology used in computing amortization are as follows: Estimated Useful Lives Amortization Methodology Customer relationships 7 years Straight-line Acquired technology 7 years Straight-line Trade names 3 years Straight-line Intangible assets consisted of the following (in thousands): December 31, 2015 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Weighted Average Useful Life (in years) Customer relationships $ 2,100 $ (350 ) $ 1,750 7.0 Acquired technology 1,700 (283 ) 1,417 7.0 Trade names 130 (51 ) 79 3.0 Total $ 3,930 $ (684 ) $ 3,246 6.9 December 31, 2014 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Weighted Average Useful Life (in years) Customer relationships $ 4,550 $ (2,312 ) $ 2,238 7.5 Acquired technology 1,700 (40 ) 1,660 7.0 Trade names 130 (7 ) 123 3.0 Proprietary software 710 (648 ) 62 8.0 Total $ 7,090 $ (3,007 ) $ 4,083 7.4
Expected Future Amortization Expense	As of December 31, 2015 , expected amortization expense over the remaining intangible asset lives is as follows (in thousands): 2016 $ 586 2017 579 2018 543 2019 543 2020 543 Thereafter 452 Total $ 3,246

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments for Operating Leases	The Company leases office facilities and certain equipment under non-cancelable operating and capital leases. Future minimum lease payments on capital leases and future payments on operating leases with remaining terms in excess of one year are as follows (in thousands): Operating Leases Capital Leases Year Ending December 31, 2016 $ 6,337 $ 2,332 2017 5,489 1,882 2018 5,197 223 2019 4,135 — 2020 4,711 — Thereafter 10,008 — Total minimum lease payments $ 35,877 4,437 Less: imputed interest (207 ) Less: current portion (2,199 ) Capital lease obligations, net of current portion $ 2,031
Schedule of Future Minimum Lease Payments for Capital Leases	The Company leases office facilities and certain equipment under non-cancelable operating and capital leases. Future minimum lease payments on capital leases and future payments on operating leases with remaining terms in excess of one year are as follows (in thousands): Operating Leases Capital Leases Year Ending December 31, 2016 $ 6,337 $ 2,332 2017 5,489 1,882 2018 5,197 223 2019 4,135 — 2020 4,711 — Thereafter 10,008 — Total minimum lease payments $ 35,877 4,437 Less: imputed interest (207 ) Less: current portion (2,199 ) Capital lease obligations, net of current portion $ 2,031

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Components of Income (Loss) before Income Taxes	The components of income (loss) before income taxes for the years ended December 31, 2015 , 2014 and 2013 were as follows (in thousands): 2015 2014 2013 Domestic $ (21,146 ) $ (36,053 ) $ (7,222 ) Foreign 10 1,580 (13,203 ) Total loss before income taxes $ (21,136 ) $ (34,473 ) $ (20,425 )
Schedule of Provision for Income Tax Expense (Benefit)	The provision for income tax expense (benefit) included the following for the years ended December 31, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Current: Federal $ — $ — $ 22 State (101 ) 11 193 Foreign 160 8 — Total 59 19 215 Deferred: Federal 37 42 (26 ) State 15 5 14 Foreign (296 ) (25 ) — Total (244 ) 22 (12 ) Total tax (benefit) expense $ (185 ) $ 41 $ 203
Components of Net Deferred Tax Assets (Liabilities)	The components of the Company’s net deferred tax assets (liabilities) as of December 31, 2015 , 2014 and 2013 were as follows (in thousands): 2015 2014 2013 Current: Deferred tax assets: Other assets $ 2,133 $ 1,615 $ 832 Valuation allowance (1,877 ) (1,562 ) (726 ) Total deferred tax assets 256 53 106 Deferred tax liabilities: Other liabilities (58 ) (57 ) (71 ) Net deferred tax (liability) asset, current $ 198 $ (4 ) $ 35 Noncurrent: Deferred tax assets: Domestic tax loss carryforwards $ 31,573 $ 28,822 $ 18,898 Foreign tax loss carryforwards 5,678 6,695 7,673 Stock-based compensation 3,375 2,546 — Tax credits 1,178 658 78 Other assets 2,214 811 866 Valuation allowance (42,156 ) (38,700 ) (26,206 ) Total deferred tax assets 1,862 832 1,309 Deferred tax liabilities: Fixed assets 2,146 622 1,149 Intangible assets 589 1,184 — Other liabilities 57 — 383 Total deferred tax liabilities 2,792 1,806 1,532 Net deferred tax liability, noncurrent $ (930 ) $ (974 ) $ (223 )
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the difference between the effective income tax rate and the statutory federal income tax rate for the years ended December 31, 2015 , 2014 and 2013 is as follows: 2015 2014 2013 U.S. statutory federal rate 34.0 % 34.0 % 34.0 % Increase (decrease) resulting from: State taxes, net of federal benefit 4.3 4.8 1.6 Nondeductible expenses (14.0 ) (0.1 ) (5.2 ) Effect of foreign tax rate differential (0.1 ) 0.6 (8.0 ) Uncertain tax position (1.5 ) (0.4 ) — Research and development credit 3.7 2.1 — Change in valuation allowance (20.3 ) (39.7 ) (22.4 ) Other (5.2 ) (1.4 ) (1.0 ) Effective tax rate 0.9 % (0.1 )% (1.0 )%
Schedule of Unrecognized Tax Benefits Roll Forward	The following table shows the changes in unrecognized tax benefits in accordance with ASC 740-10 for the years ended December 31, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Balance as of January 1, $ 782 $ — $ — Increases related to current tax positions 345 149 — Increases related to prior year tax positions 79 697 — Decreases related to prior year tax positions (411 ) (64 ) — Decreases related to the expirations of statutes of limitations (114 ) — — Balance as of December 31, $ 681 $ 782 $ —

Equity Incentive Plan and Sto29

Equity Incentive Plan and Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock-Based Compensation Expense	Stock-based compensation expense related to stock options is included in the following line items in the accompanying consolidated statements of operations for the years ended December 31, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Cost of revenue $ 992 $ 533 $ 204 Sales and marketing 4,349 2,911 607 Research and development 1,689 864 348 General and administrative 4,807 3,673 940 $ 11,837 $ 7,981 $ 2,099
Summary of Weighted-Average Assumptions Used for Estimating Fair Value of Stock Granted	The following table summarizes the assumptions used for estimating the fair value of stock options granted for the years ended December 31, 2015 , 2014 and 2013 : 2015 2014 2013 Risk-free interest rate 0.9% - 1.7% 0.3% - 2.0% 0.3% - 1.7% Expected term (years) 6.25 6.06 - 6.25 5.00 - 6.25 Expected volatility 45% - 47% 43% - 56% 43% - 59% Dividend yield 0% 0% 0%
Summary of Stock Option Activity	The following is a summary of the option activity for the year ended December 31, 2015 : Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in years) (in thousands) Outstanding balance at January 1, 2015 1,425,357 $ 9.12 Granted 456,871 10.59 Exercised (169,879 ) 5.39 Forfeited (200,511 ) 14.78 Expired (41,545 ) 25.06 Outstanding balance at December 31, 2015 1,470,293 $ 8.79 7.22 $ 8,899 Exercisable at December 31, 2015 877,515 $ 7.00 6.16 $ 6,824 Vested and expected to vest at December 31, 2015 1,379,819 $ 8.61 7.12 $ 8,577
Summary of Restricted Stock Units Award Activity	The following table summarizes the RSU activity for the year ended December 31, 2015 : Number of RSUs Weighted Average Grant-Date Fair Value Unvested RSUs as of January 1, 2015 944,734 $ 22.77 Granted 1,559,823 10.23 Vested (222,895 ) 24.78 Forfeited (331,960 ) 14.85 Unvested RSUs as of December 31, 2015 1,949,702 $ 13.85

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Schedule of Securities Excluded from Calculation of Weighted Average Common Shares Outstanding	The following securities have been excluded from the calculation of weighted average common shares outstanding because the effect is anti-dilutive for the years ended December 31, 2015 , 2014 and 2013 : 2015 2014 2013 Warrants to purchase common stock — 3,743 986,784 Stock options 1,470,293 1,425,357 2,068,641 RSUs 1,949,702 944,734 —

Segment and Geographic Inform31

Segment and Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Summary of Revenue by Geography	The following table summarizes revenue by geography for the years ended December 31, 2015 , 2014 and 2013 (in thousands): 2015 2014 2013 Revenue: Domestic $ 77,785 $ 65,750 $ 53,832 International 22,800 19,151 14,172 Total $ 100,585 $ 84,901 $ 68,004

Selected Quarterly Information

Selected Quarterly Information (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information	Three Months Ended, March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenue $ 22,590 $ 24,182 $ 24,379 $ 29,434 Gross profit 16,174 17,781 18,089 22,707 Loss from operations (9,056 ) (6,595 ) (4,744 ) (798 ) Net loss (8,956 ) (6,524 ) (4,791 ) (680 ) Net loss per share: Basic and diluted (0.36 ) (0.26 ) (0.19 ) (0.03 ) Three Months Ended, March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenue $ 19,338 $ 20,770 $ 20,966 $ 23,827 Gross profit 13,606 14,351 14,948 17,776 Loss from operations (9,280 ) (9,511 ) (8,857 ) (6,360 ) Net loss (9,370 ) (9,604 ) (9,004 ) (6,536 ) Net loss per share: Basic and diluted (0.39 ) (0.39 ) (0.36 ) (0.26 )

Significant Accounting Polici33

Significant Accounting Policies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)segment	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Significant Accounting Policies [Line Items]
Other receivables	$ 4.7	$ 1.3
Number of reportable segments | segment	1
Advertising expense	$ 4.3	$ 6.3	$ 4.6
E-Tale Holdings Limited [Member]
Significant Accounting Policies [Line Items]
Fair value inputs, discount rate	22.00%	24.00%
United States
Significant Accounting Policies [Line Items]
Restricted cash		$ 0.6

Significant Accounting Polici34

Significant Accounting Policies - Reclassifications (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of revenue (excluding depreciation)	$ 20,848	$ 20,713	$ 15,947
Depreciation - Cost of revenue	4,986	3,507	2,141
Sales and marketing	51,941	54,902	36,942
Research and development	16,060	16,215	12,426
General and administrative	24,136	20,815	13,332
Depreciation and amortization	$ 3,807	2,757	1,581
Scenario, Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of revenue (excluding depreciation)		24,220	18,088
Depreciation - Cost of revenue		0	0
Sales and marketing		55,829	37,458
Research and development		16,585	12,669
General and administrative		22,275	14,154
Depreciation and amortization		0	0
Restatement Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cost of revenue (excluding depreciation)		(3,507)	(2,141)
Depreciation - Cost of revenue		3,507	2,141
Sales and marketing		(927)	(516)
Research and development		(370)	(243)
General and administrative		(1,460)	(822)
Depreciation and amortization		$ 2,757	$ 1,581

Significant Accounting Polici35

Significant Accounting Policies - Contingent Consideration Rollforward (Details) - Contingent Consideration [Member] - E-Tale Holdings Limited [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration, beginning balance	$ 618
Change in contingent consideration fair value	79
Contingent consideration, ending balance	$ 697

Significant Accounting Polici36

Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at Beginning of Period	$ 673	$ 561	$ 191
Additions Charged to Expense/Against Revenue	1,315	737	594
Deductions	(1,203)	(625)	(224)
Balance at End of Period	$ 785	$ 673	$ 561

Significant Accounting Polici37

Significant Accounting Policies - Estimated Useful Lives for Significant Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2015
Purchased software, including internal-use software [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer hardware [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Minimum [Member] | Furniture and office equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Maximum [Member] | Furniture and office equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years

Significant Accounting Polici38

Significant Accounting Policies - Estimated Useful Lives Used in Computing Amortization (Detail)	12 Months Ended
	Dec. 31, 2015
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life of intangible asset	7 years
Acquired Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life of intangible asset	7 years
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life of intangible asset	3 years

Significant Accounting Polici39

Significant Accounting Policies - Software Development Costs (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Software and Software Development Costs [Member]
Significant Accounting Policies [Line Items]
Software development costs capitalized	$ 200,000	$ 400,000
Amortization expense related to capitalized internally developed software	300,000	200,000	$ 100,000
Net book value of capitalized internally developed software	400,000	600,000
Hosted Software Configuration Costs [Member]
Significant Accounting Policies [Line Items]
Software development costs capitalized	0	300,000
Amortization expense related to capitalized internally developed software	600,000	700,000	$ 100,000
Net book value of capitalized internally developed software	$ 600,000	$ 1,400,000

Business Combination - Addition

Business Combination - Additional Information (Details) - USD ($) $ in Thousands	Oct. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Other acquisition consideration		$ 0	$ 200	$ 0
E-Tale Holdings Limited [Member]
Business Acquisition [Line Items]
Contingent consideration liability		700
Purchase price adjustment (less than)		$ 100
Contingent consideration, maximum payment	$ 4,000
Transaction costs			$ 500
Scenario, Previously Reported [Member] | E-Tale Holdings Limited [Member]
Business Acquisition [Line Items]
Cash purchase price	8,200
Escrow deposit	1,000
Initial aggregate purchase	9,000
Contingent consideration liability	600
Other acquisition consideration	$ 200

Business Combination - Schedule

Business Combination - Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Oct. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 21,632	$ 21,518
E-Tale Holdings Limited [Member]
Business Acquisition [Line Items]
Cash			$ 124
Accounts receivable			506
Deferred tax liability			(794)
Other assets/liabilities, net			(334)
Goodwill			5,526
Total purchase price			8,958
Customer Relationships [Member] | E-Tale Holdings Limited [Member]
Business Acquisition [Line Items]
Finite-lived intangible asset acquired			2,100
Acquired Technology [Member] | E-Tale Holdings Limited [Member]
Business Acquisition [Line Items]
Finite-lived intangible asset acquired			1,700
Trade Names [Member] | E-Tale Holdings Limited [Member]
Business Acquisition [Line Items]
Finite-lived intangible asset acquired			$ 130

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 38,085	$ 32,556
Less: accumulated depreciation	(21,389)	(19,953)
Property and equipment, net	16,696	12,603
Purchased software, including internal use software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	13,213	9,366
Computer hardware [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	12,750	16,125
Furniture and office equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,698	3,473
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	8,330	3,166
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 94	$ 426

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 7.9	$ 5.7	$ 3.1
Accelerated depreciation due to headquarters relocation	$ 0.7

Goodwill and Intangible Asset44

Goodwill and Intangible Assets - Changes in Carrying Amount of Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 21,518
Adjustments related to the E-Tale acquisition	114
Goodwill, ending balance	$ 21,632

Goodwill and Intangible Asset45

Goodwill and Intangible Assets - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,930	$ 7,090
Accumulated Amortization	(684)	(3,007)
Net Carrying Amount	$ 3,246	$ 4,083
Weighted Average Useful Life (in years)	6 years 10 months 24 days	7 years 4 months 24 days
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,100	$ 4,550
Accumulated Amortization	(350)	(2,312)
Net Carrying Amount	$ 1,750	$ 2,238
Weighted Average Useful Life (in years)	7 years	7 years 6 months
Acquired Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,700	$ 1,700
Accumulated Amortization	(283)	(40)
Net Carrying Amount	$ 1,417	$ 1,660
Weighted Average Useful Life (in years)	7 years	7 years
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 130	$ 130
Accumulated Amortization	(51)	(7)
Net Carrying Amount	$ 79	$ 123
Weighted Average Useful Life (in years)	3 years	3 years
Proprietary Software [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 710
Accumulated Amortization		(648)
Net Carrying Amount		$ 62
Weighted Average Useful Life (in years)		8 years

Goodwill and Intangible Asset46

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 0.9	$ 0.5	$ 0.6

Goodwill and Intangible Asset47

Goodwill and Intangible Assets - Expected Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
2,016	$ 586
2,017	579
2,018	543
2,019	543
2,020	543
Thereafter	452
Net Carrying Amount	$ 3,246	$ 4,083

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Operating Leases
2,016	$ 6,337
2,017	5,489
2,018	5,197
2,019	4,135
2,020	4,711
Thereafter	10,008
Total minimum lease payments	35,877
Capital Leases
2,016	2,332
2,017	1,882
2,018	223
2,019	0
2,020	0
Thereafter	0
Total minimum lease payments	4,437
Less: imputed interest	(207)
Less: current portion	(2,199)
Capital lease obligations, net of current portion	$ 2,031	$ 2,014

Commitments and Contingencies49

Commitments and Contingencies - Capital Leases (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Fixed assets under capital leases, gross	$ 7.9	$ 6.6
Fixed assets under capital leases, net	$ 4.1	$ 3.3

Commitments and Contingencies50

Commitments and Contingencies - Operating Leases (Details) £ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 31, 2014lease_renewal_period	Dec. 31, 2015USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015GBP (£)
Property Subject to or Available for Operating Lease [Line Items]
Deferred rent		$ 1,100,000	$ 1,100,000	$ 2,300,000
Annual rental payments		6,337,000	6,337,000
Rent expense			3,100,000	3,400,000	$ 1,800,000
New Headquarters Lease [Member]
Property Subject to or Available for Operating Lease [Line Items]
Initial lease term	7 years
Number of additional lease renewal periods | lease_renewal_period	2
Renewal term	5 years
Annual rental payments		$ 3,200,000	$ 3,200,000
Increase In minimum annual rental payments each lease year		2.75%	2.75%			2.75%
Previous Headquarters Lease [Member]
Property Subject to or Available for Operating Lease [Line Items]
Loss associated with lease termination		$ 1,000,000
London, England office [Member]
Property Subject to or Available for Operating Lease [Line Items]
Loss associated with lease termination				$ 100,000
Remaining lease payments		3,100,000	$ 3,100,000			£ 2.1
Guarantor obligation, current carrying value		$ 0	$ 0

Commitments and Contingencies51

Commitments and Contingencies - Litigation and Other Contingencies (Details) $ in Millions	Dec. 31, 2015USD ($)
Commitments and Contingencies Disclosure [Abstract]
Tax accrual	$ 0.6
Tax exposure, maximum amount	$ 3.9

Debt - Loan and Security Agreem

Debt - Loan and Security Agreement (Details) - Revolving Credit Facility [Member] - December 2009 Loan and Security Agreement Debt [Member] - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 17, 2014
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 10,000,000
Interest rate	3.50%
Unused facility fee	0.15%
Future principal payments	$ 0	$ 0
Prime Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.25%

Debt - Subordinated Debt (Detai

Debt - Subordinated Debt (Details) - USD ($)	1 Months Ended	12 Months Ended
	Nov. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Debt Instrument [Line Items]
Payment of debt extinguishment costs		$ 0	$ 0	$ 1,200,000
Loss on extinguishment of debt		$ 0	$ 0	3,112,000
March 2012 Loan and Security Agreement Debt [Member] | Subordinated Loan [Member]
Debt Instrument [Line Items]
Interest rate						10.50%
Debt borrowed					$ 10,000,000
Early repayment of subordinated debt	$ 11,300,000
Payment of debt extinguishment costs	$ 1,200,000
Loss on extinguishment of debt				$ 3,100,000

Income Taxes - Components of In

Income Taxes - Components of Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Domestic	$ (21,146)	$ (36,053)	$ (7,222)
Foreign	10	1,580	(13,203)
Loss before income taxes	$ (21,136)	$ (34,473)	$ (20,425)

Income Taxes - Provision for In

Income Taxes - Provision for Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
Federal	$ 0	$ 0	$ 22
State	(101)	11	193
Foreign	160	8	0
Total	59	19	215
Deferred:
Federal	37	42	(26)
State	15	5	14
Foreign	(296)	(25)	0
Total	(244)	22	(12)
Total tax (benefit) expense	$ (185)	$ 41	$ 203

Income Taxes - Components of Ne

Income Taxes - Components of Net Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Other assets	$ 2,133	$ 1,615	$ 832
Valuation allowance	(1,877)	(1,562)	(726)
Total deferred tax assets	256	53	106
Deferred tax liabilities:
Other liabilities	(58)	(57)	(71)
Net deferred tax asset, current	198		35
Net deferred tax liability, current		(4)
Deferred tax assets:
Domestic tax loss carryforwards	31,573	28,822	18,898
Foreign tax loss carryforwards	5,678	6,695	7,673
Stock-based compensation	3,375	2,546	0
Tax credits	1,178	658	78
Other assets	2,214	811	866
Valuation allowance	(42,156)	(38,700)	(26,206)
Total deferred tax assets	1,862	832	1,309
Deferred tax liabilities:
Fixed assets	2,146	622	1,149
Intangible assets	589	1,184	0
Other liabilities	57	0	383
Total deferred tax liabilities	2,792	1,806	1,532
Net deferred tax liability, noncurrent	$ (930)	$ (974)	$ (223)

Income Taxes - Operating Loss C

Income Taxes - Operating Loss Carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Carryforward related to excess stock option benefits	$ 21.5
Increase in valuation allowance	3.8
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	106.4	$ 99.3	$ 62.5
State [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	117	104.2	55.2
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 27.3	$ 30.9	$ 25.1

Income Taxes - Tax Credit Carry

Income Taxes - Tax Credit Carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Federal [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 1.6	$ 0.8	$ 0.1

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details)	Dec. 31, 2015USD ($)return	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Income Tax Disclosure [Abstract]
Undistributed foreign earnings, deferred tax liability	$ 0
Undistributed earnings of foreign subsidiaries		$ 800,000	$ 800,000
Unrecognized tax benefits, income tax penalties and interest accrued	$ 0	$ 0
Income tax returns under examination, number | return	0

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Reconciliation (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
U.S. statutory federal rate	34.00%	34.00%	34.00%
Increase (decrease) resulting from:
State taxes, net of federal benefit	4.30%	4.80%	1.60%
Nondeductible expenses	(14.00%)	(0.10%)	(5.20%)
Effect of foreign tax rate differential	(0.10%)	0.60%	(8.00%)
Uncertain tax position	(1.50%)	(0.40%)	0.00%
Research and development credit	3.70%	2.10%	0.00%
Change in valuation allowance	(20.30%)	(39.70%)	(22.40%)
Other	(5.20%)	(1.40%)	(1.00%)
Effective tax rate	0.90%	(0.10%)	(1.00%)

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits
Balance as of January 1	$ 782	$ 0	$ 0
Increases related to current tax positions	345	149	0
Increases related to prior year tax positions	79	697	0
Decreases related to prior year tax positions	(411)	(64)	0
Decreases related to the expirations of statutes of limitations	(114)	0	0
Balance as of December 31	$ 681	$ 782	$ 0

Warrants - Additional Informati

Warrants - Additional Information (Detail) - Common Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2008	Dec. 31, 2007
Class of Warrant or Right [Line Items]
Warrants to purchase stock (in shares)			1,616,113
Exercise of common stock warrants (in shares)	664,058	662,362
$16.00 [Member]
Class of Warrant or Right [Line Items]
Warrants to purchase stock (in shares)				958,019
Warrants exercise price (in dollars per share)				$ 16
$10.96 [Member]
Class of Warrant or Right [Line Items]
Warrants to purchase stock (in shares)			658,094
Warrants exercise price (in dollars per share)			$ 10.96

Equity Incentive Plan and Sto63

Equity Incentive Plan and Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jan. 01, 2016	May. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance		1,250,000
Common stock reserved for issuance increase, automatic increase, term		10 years
Number of shares reserved for issuance, automatic increase, percent of common stock outstanding of preceding calendar year		5.00%
Number of shares available for future grant			1,064,122
Subsequent Event [Member] | 2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized	1,261,547
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)			$ 4.29	$ 13.88	$ 5.29
Total fair value of stock options vested during period			$ 1.2	$ 1.5	$ 0.9
Options, compensation cost not yet recognized			$ 1.2
Unrecognized compensation cost related to nonvested awards, weighted-average period recognized			1 year 11 months 10 days
Aggregate intrinsic value of stock options exercised			$ 1.2	$ 16	$ 17.6
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested awards, weighted-average period recognized			1 year 9 months 20 days
Nonvested RSUs, compensation cost not yet recognized			$ 11.6

Equity Incentive Plan and Sto64

Equity Incentive Plan and Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock-Based Compensation [Line Items]
Share-based Compensation Expense	$ 11,837	$ 7,981	$ 2,099
Cost of Revenue [Member]
Stock-Based Compensation [Line Items]
Share-based Compensation Expense	992	533	204
Sales and Marketing [Member]
Stock-Based Compensation [Line Items]
Share-based Compensation Expense	4,349	2,911	607
Research and Development [Member]
Stock-Based Compensation [Line Items]
Share-based Compensation Expense	1,689	864	348
General and Administrative [Member]
Stock-Based Compensation [Line Items]
Share-based Compensation Expense	$ 4,807	$ 3,673	$ 940

Equity Incentive Plan and Sto65

Equity Incentive Plan and Stock-Based Compensation - Summary of Weighted-Average Assumptions Used for Estimating Fair Value of Stock Granted (Detail) - Stock Options [Member]	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.90%	0.30%	0.30%
Expected term (years)	6 years 3 months	6 years 21 days	5 years
Expected volatility	45.00%	43.00%	43.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.70%	2.00%	1.70%
Expected term (years)		6 years 3 months	6 years 3 months
Expected volatility	47.00%	56.00%	59.00%

Equity Incentive Plan and Sto66

Equity Incentive Plan and Stock-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Number of Options
Outstanding beginning of period (in shares) | shares	1,425,357
Granted (in shares) | shares	456,871
Exercised (in shares) | shares	(169,879)
Forfeited (in shares) | shares	(200,511)
Expired (in shares) | shares	(41,545)
Outstanding end of period (in shares) | shares	1,470,293
Exercisable (in shares) | shares	877,515
Vested and expected to vest (in shares) | shares	1,379,819
Weighted Average Exercise Price
Outstanding beginning of period (in dollars per share) | $ / shares	$ 9.12
Granted (in dollars per share) | $ / shares	10.59
Exercised (in dollars per share) | $ / shares	5.39
Forfeited (in dollars per share) | $ / shares	14.78
Expired (in dollars per share) | $ / shares	25.06
Outstanding end of period (in dollars per share) | $ / shares	8.79
Exercisable (in dollars per share) | $ / shares	7
Vested and expected to vest (in dollars per share) | $ / shares	$ 8.61
Weighted Average Remaining Contractual Term
Outstanding	7 years 2 months 18 days
Exercisable	6 years 1 month 27 days
Vested and expected to vest	7 years 1 month 13 days
Aggregate Intrinsic Value
Ending balance | $	$ 8,899
Exercisable | $	6,824
Vested and expected to vest | $	$ 8,577

Equity Incentive Plan and Sto67

Equity Incentive Plan and Stock-Based Compensation - Summary of Restricted Stock Units Activity (Detail) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Number of RSUs
Unvested RSUs as of beginning of period (in shares) | shares	944,734
Granted (in shares) | shares	1,559,823
Vested (in shares) | shares	(222,895)
Forfeited (in shares) | shares	(331,960)
Unvested RSUs as of end of period (in shares) | shares	1,949,702
Weighted average grant date fair value
Unvested RSU's as of beginning of period (in dollars per share) | $ / shares	$ 22.77
Granted (in dollars per share) | $ / shares	10.23
Vested (in dollars per share) | $ / shares	24.78
Forfeited (in dollars per share) | $ / shares	14.85
Unvested RSU's as of end of period (in dollars per share) | $ / shares	$ 13.85

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Securities Excluded from Calculation of Weighted Average Common Shares Outstanding (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of weighted average common shares outstanding (in shares)	0	3,743	986,784
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of weighted average common shares outstanding (in shares)	1,470,293	1,425,357	2,068,641
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of weighted average common shares outstanding (in shares)	1,949,702	944,734	0

Segment and Geographic Inform69

Segment and Geographic Information - Summary of Revenue by Geography (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenue	$ 29,434	$ 24,379	$ 24,182	$ 22,590	$ 23,827	$ 20,966	$ 20,770	$ 19,338	$ 100,585	$ 84,901	$ 68,004
United States
Segment Reporting Information [Line Items]
Revenue									77,785	65,750	53,832
Non-US [Member]
Segment Reporting Information [Line Items]
Revenue									$ 22,800	$ 19,151	$ 14,172

Segment and Geographic Inform70

Segment and Geographic Information - Additional Information (Detail) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)segment	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment									1
Number of operating segments | segment									1
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue | $	$ 29,434	$ 24,379	$ 24,182	$ 22,590	$ 23,827	$ 20,966	$ 20,770	$ 19,338	$ 100,585	$ 84,901	$ 68,004
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue | $									$ 13,600	$ 11,400	$ 8,900

Retirement Plan (Details)

Retirement Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Employer contributions	$ 0.8	$ 0.8	$ 0.5

Selected Quarterly Informatio72

Selected Quarterly Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 29,434	$ 24,379	$ 24,182	$ 22,590	$ 23,827	$ 20,966	$ 20,770	$ 19,338	$ 100,585	$ 84,901	$ 68,004
Gross profit	22,707	18,089	17,781	16,174	17,776	14,948	14,351	13,606	74,751	60,681	49,916
Loss from operations	(798)	(4,744)	(6,595)	(9,056)	(6,360)	(8,857)	(9,511)	(9,280)	(21,193)	(34,008)	(14,365)
Net loss	$ (680)	$ (4,791)	$ (6,524)	$ (8,956)	$ (6,536)	$ (9,004)	$ (9,604)	$ (9,370)	$ (20,951)	$ (34,514)	$ (20,628)
Net (loss) income per share:
Basic and diluted (in dollars per share)	$ (0.03)	$ (0.19)	$ (0.26)	$ (0.36)	$ (0.26)	$ (0.36)	$ (0.39)	$ (0.39)	$ (0.84)	$ (1.40)	$ (1.51)