Rocket Fuel 10-K 16 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 28, 2015	Jun. 30, 2014
Document and Entity Information
Entity Registrant Name	Rocket Fuel Inc.
Entity Central Index Key	1477200
Document Type	10-K
Document Period End Date	31-Dec-14
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$599,788,529
Entity Common Stock, Shares Outstanding		42,098,774
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current Assets:
Cash and cash equivalents	$107,056	$113,873
Accounts receivable, net	135,400	90,502
Deferred tax assets	1,716	207
Prepaid expenses	3,698	2,164
Other current assets	12,531	3,962
Total current assets	260,401	210,708
Property, equipment and software, net	89,441	25,794
Restricted cash	2,915	0
Intangible assets	69,299	0
Goodwill	115,412	0
Other assets	1,797	1,006
Total assets	539,265	237,508
Current Liabilities:
Accounts payable	76,085	39,910
Accrued and other current liabilities	33,258	21,584
Deferred revenue	593	918
Current portion of capital leases	5,482	203
Current portion of debt	45,705	7,243
Total current liabilities	161,123	69,858
Long-term debt—Less current portion	23,335	19,568
Capital leases—Less current portion	12,341	412
Deferred rent—Less current portion	26,818	3,909
Deferred tax liabilities	2,068	207
Other liabilities	814	387
Total liabilities	226,499	94,341
Commitments and contingencies (Note 12)
Stockholders’ Equity
Common stock, $0.001 par value— 1,000,000,000 authorized as of December 31, 2014 and 2013, respectively; 42,002,533 and 32,825,992 issued and outstanding as of December 31, 2014 and 2013, respectively	42	33
Additional paid-in capital	421,630	187,624
Accumulated other comprehensive loss	-120	-15
Accumulated deficit	-108,786	-44,475
Total stockholders’ equity	312,766	143,167
Total liabilities and stockholders’ equity	$539,265	$237,508

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	42,002,533	32,825,992
Common stock, shares outstanding	42,002,533	32,825,992
Preferred Stock, Shares Authorized	100,000,000	100,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Revenue	$408,641	$240,605	$106,589
Costs and expenses:
Media costs	173,477	103,637	50,669
Other cost of revenue	48,586	21,883	9,342
Research and development	39,794	17,714	4,876
Sales and marketing	146,430	83,345	41,069
General and administrative	60,545	28,708	8,403
Total costs and expenses	468,832	255,287	114,359
Operating loss	-60,191	-14,682	-7,770
Other expense, net:
Interest expense	-3,092	-917	-316
Other income (expense)—net	-5,267	-308	135
Change in fair value of convertible preferred stock warrant liability	0	-4,740	-2,308
Other expense, net	-8,359	-5,965	-2,489
Loss before income taxes	-68,550	-20,647	-10,259
Income tax (benefit) provision	4,239	-285	-84
Net loss	($64,311)	($20,932)	($10,343)
Basic and diluted net loss per share attributable to common stockholders	($1.74)	($1.38)	($1.29)
Basic and diluted weighted-average shares used to compute net loss per share attributable to common stockholders	37,001	15,177	8,024

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net loss	($64,311)	($20,932)	($10,343)
Other comprehensive loss:
Foreign currency translation adjustments	-105	69	-77
Comprehensive loss	($64,416)	($20,863)	($10,420)

CONSOLIDATED_STATEMENTS_OF_STO

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $)	Total	Series C1 Preferred Stock [Member]	Convertible Preferred Stock [Member]	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2011	$13,388		$26,224	$7	$364	($7)	($13,200)
Balance (in shares) at Dec. 31, 2011			16,546,257	7,927,771
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercises of employee stock options, net of repurchases	181			1	180
Stock Issued During Period, Shares, Restricted Stock Award, Gross	13,571
Stock Issued During Period, Value, Restricted Stock Award, Gross	33				33
Issuance of common stock upon exercises of employee stock options, net of repurchases (in shares)				738,699
Issuance of stock, net of issuance costs	34,393	34,393
Issuance of stock, net of issuance costs (in shares)		2,932,675
Stock-based compensation	3,288				3,288
Foreign currency translation adjustment	-77					-77
Net loss	-10,343						-10,343
Balance at Dec. 31, 2012	40,863		60,617	8	3,865	-84	-23,543
Balance (in shares) at Dec. 31, 2012			19,478,932	8,680,041
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercises of employee stock options, net of repurchases	637			1	636
Stock Issued During Period, Shares, Conversion of Convertible Securities			-19,478,932	19,478,932
Stock Issued During Period, Value, Conversion of Convertible Securities	0		-60,617	19	60,598
Common Stock Issued During Period Shares Conversion of Warrants	266,530
Common Stock Issued During Period Value Conversion of Warrants	7,580			1	7,579
Issuance of common stock upon exercises of employee stock options, net of repurchases (in shares)				400,489
Issuance of stock, net of issuance costs	103,307			4	103,303
Issuance of stock, net of issuance costs (in shares)	4,000,000
Stock-based compensation	11,643				11,643
Foreign currency translation adjustment	69					69
Net loss	-20,932						-20,932
Balance at Dec. 31, 2013	143,167			33	187,624	-15	-44,475
Balance (in shares) at Dec. 31, 2013				32,825,992
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercises of employee stock options, net of repurchases	4,545			2	4,543
Issuance of common stock upon exercises of employee stock options, net of repurchases (in shares)	1,499,190			1,473,565
Issuance of common stock upon vesting of restricted stock units	0			0
Issuance of common stock upon exercise vesting of restricted stock units (in shares)				118,147
Shares withheld related to net share settlement of restricted stock units	-567				-567
Stock Issued During Period, Shares, Acquisitions				5,253,084
Stock Issued During Period, Value, Acquisitions	82,421			5	82,416
Shares withheld related to net share settlement of restricted stock units (in shares)				-38,242
Issuance of common stock in connection with employee stock purchase plan	6,454				6,454
Issuance of stock, net of issuance costs	115,403			2	115,401
Issuance of stock, net of issuance costs (in shares)				2,000,000
Issuance of common stock in connection with employee stock purchase plan (in shares)				369,987
Stock-based compensation	25,481				25,481
Foreign currency translation adjustment	-105					-105
Tax benefit from stock-based award activity	278				278
Net loss	-64,311						-64,311
Balance at Dec. 31, 2014	$312,766			$42	$421,630	($120)	($108,786)
Balance (in shares) at Dec. 31, 2014				42,002,533

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OPERATING ACTIVITIES:
Net loss	($64,311)	($20,932)	($10,343)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	23,670	7,855	3,600
Stock-based compensation	23,838	10,921	3,288
Deferred taxes	-5,418	0	0
Excess tax benefit from stock-based activity	-278	0	0
Other non-cash adjustments, net	871	1,016	389
Change in fair value of preferred stock warrant liability	0	4,740	2,308
Changes in operating assets and liabilities, net of effects of acquisition:
Accounts receivable	-25,134	-43,803	-31,129
Prepaid expenses and other assets	-9,153	-5,182	-1,140
Accounts payable	26,952	21,009	9,612
Accrued and other liabilities	-1,085	14,317	4,066
Deferred rent	24,068	3,189	359
Deferred revenue	-334	732	187
Net cash used in operating activities	-6,314	-6,138	-18,803
INVESTING ACTIVITIES:
Purchases of property, equipment and software	-47,865	-14,294	-4,089
Business acquisition, net	-97,444	0	0
Capitalized internal-use software development costs	-7,600	-5,592	-4,674
Changes in restricted cash	-2,203	0	0
Net cash used in investing activities	-155,112	-19,886	-8,763
FINANCING ACTIVITIES:
Proceeds from the issuance of common stock in initial and follow-on public offering, net of underwriting discounts, commission and issuance costs	115,403	103,612	0
Proceeds from the issuance of convertible preferred stock, net of issuance costs	0	0	34,393
Proceeds from exercise of common stock options and common stock warrants	3,725	1,400	512
Excess tax benefit from stock-based activity	278	0	0
Proceeds from issuance of common stock from employee stock purchase plan	6,454	0	0
Tax withholdings related to net share settlements of restricted stock units	-567	0	0
Repayment of capital lease obligations	-1,335	0	0
Proceeds from debt facilities, net of debt issuance costs	44,479	46,804	9,000
Repayment of debt facilities	-13,578	-26,967	-6,421
Net cash provided by financing activities	154,859	124,849	37,484
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	-250	152	-93
CHANGE IN CASH AND CASH EQUIVALENTS	-6,817	98,977	9,825
CASH AND CASH EQUIVALENTS—Beginning of period	113,873	14,896	5,071
CASH AND CASH EQUIVALENTS—End of period	107,056	113,873	14,896
SUPPLEMENTAL DISCLOSURES OF OTHER CASH FLOW INFORMATION:
Cash paid for income taxes, net of refunds	1,035	492	0
Cash paid for interest	2,840	835	286
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property and equipment recorded in accounts payable and accruals	2,077	2,349	882
Offering costs recorded in accrued liabilities	0	413	15
Property, plant and equipment acquired under capital lease obligations	18,619	615	0
Vesting of early exercised options	742	416	125
Stock-based compensation capitalized in internal-use software costs	1,643	722	0
Issuance of common stock in connection with acquisition	82,421	0	0
Conversion of convertible preferred stock to common stock	0	60,617	0
Conversion of preferred stock warrants to common stock	$0	$7,481	$0

NATURE_OF_BUSINESS_AND_SUMMARY

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

NOTE 1. NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Rocket Fuel Inc. (the “Company”) was incorporated as a Delaware corporation on March 25, 2008. The Company is a provider of artificial-intelligence digital advertising solutions headquartered in Redwood City, California, and has offices in various cities across the United States. The Company established a wholly-owned subsidiary in the United Kingdom in 2011, in Canada in 2013, and in Brazil in 2014. The United Kingdom subsidiary has offices throughout Europe and in Australia and established a wholly-owned subsidiary in Germany in 2013.

In September 2013, the Company completed the initial public offering of its common stock (the “IPO”) whereby 4,000,000 shares of common stock were sold by the Company and 600,000 shares of common stock were sold by selling stockholders. The public offering price of the shares sold in the offering was $29.00 per share. The Company did not receive any proceeds from the sale of shares by the selling stockholders. The total gross proceeds from the offering to the Company were $116.0 million. After deducting underwriters’ discounts and commissions and offering expenses, the aggregate net proceeds received by the Company totaled approximately $103.3 million.

In February 2014, the Company completed an underwritten follow-on public offering (the “Follow-on Offering”) of its common stock in which 2,000,000 shares of common stock were sold by the Company and 3,000,000 shares of common stock were sold by selling stockholders. The public offering price of the shares sold in the offering was $61.00 per share. The Company did not receive any proceeds from the sale of shares by the selling stockholders. The total gross proceeds from the offering to the Company were $122.0 million. After deducting underwriters’ discounts and commissions and offering expenses, the aggregate net proceeds received by the Company totaled approximately $115.4 million.

Principles of Consolidation—The consolidated financial statements include the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

Use of Estimates—The preparation of consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Such estimates include, but are not limited to, provisions for doubtful accounts, the amount of software development costs which should be capitalized, future taxable income, the useful lives of long-lived and intangible assets and the assumptions used for purposes of determining stock-based compensation. Actual results could differ from those estimates.

Foreign Currency Translation—The Company’s foreign subsidiaries record their assets, liabilities and results of operations in their local currencies, which are their functional currencies. The Company translates its subsidiaries' consolidated financial statements into U.S. dollars each reporting period for purposes of consolidation.

Assets and liabilities of the Company’s foreign subsidiaries are translated at the period-end currency exchange rates, certain equity accounts are translated at historical exchange rates and revenue, expenses, gains and losses are translated at the average currency exchange rates in effect for the period. The effects of these translation adjustments are reported in a separate component of stockholders’ equity titled accumulated other comprehensive loss.

Fair Value of Financial Instruments—The Company’s financial instruments consist principally of cash equivalents, accounts receivable, accounts payable, term debt and revolving credit facilities. The fair value of the Company’s cash equivalents is determined based on quoted prices in active markets for identical assets for its money market funds. The recorded values of the Company’s accounts receivable, accounts payable and accrued and other current liabilities approximate their current fair values due to the relatively short-term nature of these accounts. The Company believes that the fair value of the capital leases, term debt and revolving credit facilities approximates its recorded amount as of December 31, 2014 as the interest rates on the term debt and revolving credit facilities are variable and the rates for each are based on market interest rates after consideration of default and credit risk (using level 2 inputs).

Cash and Cash Equivalents—Cash consists of cash maintained in checking and savings accounts. All highly liquid investments purchased with an original maturity date of 90 days or less at the date of purchase are considered to be cash equivalents. Cash equivalents consist of money market funds.

Restricted Cash—Restricted cash as of December 31, 2014 consists of cash required to be deposited with financial institutions for security deposits for some of the Company's office lease agreements.

Concentration of Credit Risk—Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and accounts receivable. A significant portion of the Company’s cash is held at three major financial institutions that the Company's management has assessed to be of high credit quality. The Company has not experienced any losses in such accounts.

The Company mitigates its credit risk with respect to accounts receivable by performing credit evaluations and monitoring agencies' and advertisers' accounts receivable balances. As of December 31, 2014, two agency holding companies and no single advertiser accounted for 10% of more of accounts receivable. As of December 31, 2013, no single agency holding company or advertiser accounted for 10% or more of accounts receivable.

With respect to revenue concentration, the Company defines a customer as an advertiser that is a distinct source of revenue and is legally bound to pay for the advertising services that the Company delivers on the advertiser’s behalf. The Company counts all advertisers within a single corporate structure as one customer even in cases where multiple brands, branches or divisions of an organization enter into separate contracts with the Company. During the years ended December 31, 2014, 2013 and 2012, no single customer represented 10% or more of revenue.

The Company also monitors the percentage of revenue from advertising agencies, even though advertising agencies that act on behalf of the Company’s advertisers are not considered customers based on the definition above. If all branches and divisions within each global advertising agency were considered to be a single agency for this purpose, two agency holding companies would have been associated with 10% or more of revenue during the years ended December 31, 2014 and 2013 and three agency holding companies would have been associated with 10% or more of revenue during the year ended December 31, 2012.

Provision for Doubtful Accounts and Sales Reserves—The Company records a provision for doubtful accounts based on historical experience and a detailed assessment of the collectability of its accounts receivable. In estimating the allowance for doubtful accounts, management considers, among other factors, the aging of the accounts receivable, historical write-offs and the credit-worthiness of each customer. The Company also estimates sales returns and allowances in the same period the related revenue is recorded. These estimates are based on an analysis of credits issued for billing corrections. If circumstances change, such as higher-than-expected defaults or an unexpected material adverse change in a major customer’s ability to meet its financial obligations, the Company’s estimate of these provisions could change by a material amount.

The following is a summary of activities in allowance for doubtful accounts and sales reserves for the fiscal years indicated (in thousands):

Years ended December 31,

Allowances Beginning Balance

Charged Against Revenue

Charged to Expense

Write-offs, Adjustments, Net of Recovery

Allowances Ending Balance

2014

$

1,752

$

796

$

523

$

(860

)

$

2,211

2013

1,003

160

569

20

1,752

2012

442

365

285

(89

)

1,003

Property and Equipment—Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization is computed using the straight-line method over the estimated useful lives of the related assets. Maintenance and repairs are charged to expense as incurred, and improvements and betterments are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation or amortization, as applicable, are removed from the balance sheet and any resulting gain or loss is reflected in operations in the period realized.

Construction in progress primarily includes costs related to the leasehold improvements. Interest capitalized during the periods presented was not material.

Leasehold improvements are amortized on a straight-line basis over the term of the lease, or the useful life of the assets, whichever is shorter. Depreciation and amortization periods for the Company’s property and equipment are as follows:

Asset Classification

Estimated Useful Life

Capitalized internal-use software costs

2–3 years

Computer hardware and software

2–3 years

Furniture and fixtures

5 years

Internal-Use Software Development Costs—The Company incurs costs to develop software for internal use. The Company expenses all costs that relate to the planning and post implementation phases of development as research and development expense. The Company capitalizes costs when preliminary efforts are successfully completed, management has authorized and committed project funding, and it is probable that the project will be completed and will be used as intended. Costs incurred for enhancements that are expected to result in additional material functionality are capitalized. The Company capitalized $9.4 million, $6.3 million and $4.7 million for the years ended December 31, 2014, 2013 and 2012, respectively. These capitalized amounts are included in property, equipment and software—net on the consolidated balance sheets. Amortization commences when the website or software for internal use is ready for its intended use and the amortization period is the estimated useful life of the related asset.

Impairment of Long-lived Assets—The Company periodically reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset is impaired or the estimated useful life is no longer appropriate. If indicators of impairment exist and the undiscounted projected cash flows associated with an asset are less than the carrying amount of the asset, an impairment loss is recorded to write the asset down to its estimated fair value. Fair value is estimated based on discounted future cash flows. No impairment charges were recorded during the years ended December 31, 2014, 2013 and 2012.

Business Combinations—The Company accounts for business combinations using the acquisition accounting method as required under the provisions of FASB ASC 805, Business Combinations, or ASC 805. The total purchase price is allocated to the assets acquired and liabilities assumed based on fair values at the date of acquisition. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the identifiable assets acquired and the liabilities assumed.

Best estimates and assumptions are used in the purchase price allocation process to accurately value assets acquired and liabilities assumed at the business combination date. These estimates and assumptions are inherently uncertain and subject to refinement. As a result, during the preliminary purchase price allocation period, which may be up to one year from the business combination date, the Company may record adjustments to the assets acquired and liabilities assumed, with the corresponding adjustment to goodwill. After the preliminary purchase price allocation period, adjustments are recorded in the operating results in the period in which the adjustments were determined.

The fair value assigned to identifiable intangible assets acquired is determined using the income approach which discounts expected future cash flows to present value using estimations and assumptions determined by management. The identifiable intangible assets are subject to amortization on a straight-line basis as this best approximates the benefit period related to these assets.

The excess of the purchase price over the identified tangible and intangible assets, less liabilities assumed, is recorded as goodwill and primarily reflects the value of the synergies expected to be generated from combining the Company's and the acquired entity’s technology and operations. Generally, the goodwill is not deductible for income tax purposes.

Goodwill, Intangibles and Impairment Assessments —Goodwill represents the excess of the aggregate purchase price paid over the fair value of the net tangible and intangible assets acquired. Intangible assets that are not considered to have an indefinite useful life are amortized over their useful lives. The Company evaluates the estimated remaining useful lives of purchased intangible assets and whether events or changes in circumstances warrant a revision to the remaining periods of amortization.

Goodwill is not amortized and is tested for impairment at least annually or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. The Company has determined that it operates as one reporting unit and has selected December 1 as the date to perform its annual impairment test.

In the impairment assessment of its goodwill, the Company performs a two step impairment test, which involves assumptions regarding estimated future cash flows to be derived from the Company. If these estimates or their related assumptions change in the future, the Company may be required to record impairment for these assets. The first step of the impairment test involves comparing the fair value of the reporting unit to its net book value, including goodwill. If the net book value exceeds its fair value, then the Company would perform the second step of the goodwill impairment test to determine the amount of the impairment loss. The impairment loss would be calculated by comparing the implied fair value of the Company to its net book value. In calculating the implied fair value of the Company’s goodwill, the fair value of the Company would be allocated to all of the other assets and liabilities based on their fair values. The excess of the fair value of the Company over the amount assigned to its other assets and liabilities is the implied fair value of goodwill. An impairment loss would be recognized when the carrying amount of goodwill exceeds its implied fair value. There has been no impairment of goodwill during the year ended December 31, 2014, as the Company's reporting unit's fair value was substantially in excess of the carrying value based on the annual goodwill impairment test.

Revenue Recognition—The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred or a service has been provided, customer fees are fixed or determinable, and collection is reasonably assured.

Demand Side Platform—To date, the Company has generated most of its revenue by delivering digital advertisements to Internet users through various channels, including display, mobile, social and video. This aspect of its business is referred to as a demand side platform, or “DSP.” These arrangements are typically with advertising agencies on behalf of their advertiser clients and are generally evidenced by a fully-executed insertion order (“IO”) and are generally cancellable by the customer as to any unfulfilled portion without penalty. Generally, IOs describe the campaign objectives, state the number and type of advertising impressions to be delivered, the agreed upon rate for each delivered impression, and a fixed period of time for delivery.

Customers are typically billed on a monthly basis for each campaign for impressions delivered during the prior month. The Company determines collectability by performing ongoing credit evaluations and monitoring its customers’ accounts receivable balances. For new customers and their agents, which may be advertising agencies or other third parties, the Company performs a credit check with an independent credit agency and may check credit references to determine creditworthiness. The Company only recognizes revenue when collection is reasonably assured.

The determination of whether revenue from DSP arrangements should be reported on a gross or net basis is based on an assessment of whether the Company is acting as the principal or an agent in the transaction. In determining whether the Company acts as the principal or an agent, the Company follows the accounting guidance for principal-agent considerations. While none of the factors identified in this guidance is individually considered presumptive or determinative, the Company has concluded that it acts as a principal with respect to these arrangements because (a) the Company is the primary obligor and is responsible for (i) fulfilling the advertisement delivery, (ii) establishing the selling prices for delivery of the advertisements, (iii) selecting the media to fulfill the insertion order, and (iv) performing all billing and collection activities including retaining credit risk, and (b) the Company has the risk of fluctuating costs from its media vendors relative to fixed pricing negotiated with its customers and has discretion in selecting media vendors when fulfilling a customer’s campaign. Based on this conclusion, the Company reports revenue earned and costs incurred with respect to its full-service DSP on a gross basis.

In addition to delivering internet advertising through its full-service DSP, the Company licenses a self-service version of its DSP Based on the accounting guidance for principal-agent considerations, the Company has concluded that it acts as an agent with respect to these arrangements because (i) the Company is not the primary obligor, (ii) the Company does not have inventory risk as the customer chooses the inventory to purchase on a real-time basis, (iii) the media spend of the campaign is determined by the customer through the real-time bidding process, and (iv) the amount earned by the Company is based on a percentage of the media spend of the customer’s campaign. Based on this conclusion, the Company reports revenue earned and costs incurred with respect to its self-service DSP on a net basis.

On occasion, the Company has offered customer incentive programs that provide rebates after achieving a specified level of advertising spending. The Company records reductions to revenue for estimated commitments related to these customer incentive programs. For transactions involving incentives, the Company recognizes revenue net of the estimated amount to be paid by rebate, provided that the rebate amount can be reasonably and reliably estimated and the other conditions for revenue recognition have been met. The Company’s policy requires that, if rebates cannot be reliably estimated, revenue is not recognized until reliable estimates can be made or the rebate program lapses.

Data Management Platform—The Company licenses the right to access its data management platform ("DMP") to agencies and advertisers for their own use since its acquisition of [x+1]. These arrangements typically run over a period of one year or more and do not provide the customer with the right or ability to take possession of the platform. Revenue from license agreements is recognized ratably over the license term and was not material in the twelve months ended December 31, 2014.

The Company also provides professional services such as implementation, support and training for its platform. Revenue is deferred until the services are completed and then recognized ratably over the term of the agreement.

Multiple-Element Arrangements—The Company enters into arrangements to sell advertising that includes different media placements or ad services that are delivered at the same time during the campaign period, or within close proximity of one another. The Company allocates arrangement consideration in multiple-deliverable revenue arrangements at the inception of an arrangement to all deliverables or those packages in which all components of the package are delivered at the same time, based on the relative selling price method in accordance with the selling price hierarchy, which includes: (1) vendor-specific objective evidence (“VSOE”), if available; (2) third-party evidence (“TPE”), if VSOE is not available; and (3) best estimate of selling price (“BESP”), if neither VSOE nor TPE is available. To date, the Company has not been able to establish VSOE or selling price based on TPE for any of its advertising offerings.    When it is unable to establish selling price using VSOE or TPE, the Company uses BESP in its allocation of arrangement consideration. The objective of BESP is to determine the price at which the Company would transact a sale if the service were sold on a stand-alone basis. BESP is generally used to allocate the selling price to deliverables in the Company’s multiple element arrangements. The Company determines BESP for deliverables by considering multiple factors, including, but not limited to, prices it charges for similar offerings, market conditions, competitive landscape and pricing practices. In particular, the Company reviews multiple data points to determine BESP, including price lists used by the Company’s sales team in pricing negotiations, historical average and median pricing achieved in prior contractual customer arrangements and input from the Company’s sales operation department regarding what it believes the deliverables could be sold for on a stand-alone basis. BESP is determined at an advertising unit level that is consistent with the Company’s underlying market strategy and stratified based on specific consideration of channel, geography, industry and size, as deemed necessary. The Company regularly reviews BESP.

With some customers, the Company enters into arrangements for both DMP and DSP services at the same time, or within close proximity of one another. In such circumstances, each element is accounted for as a separate unit of accounting because the following criteria are met: the delivered services have value to the customer on a standalone basis as the services are sold separately; the arrangement does not provide the right to return any of the delivered services and performance of the undelivered services is considered probable and is substantially controlled by the Company.

The Company recognizes the relative fair value of advertising services as they are delivered, assuming all other revenue recognition criteria are met. The Company limits the amount of allocable arrangement consideration to amounts that are fixed or determinable and that are not contingent on future performance or future deliverables.

Deferred revenue is comprised of contractual billings in excess of recognized revenue and payments received in advance of revenue recognition.

Media costs—Media costs consists primarily of cost for advertising impressions purchased from real-time advertising exchanges and other third parties.

Other cost of revenue—Other cost of revenue consists primarily of third-party data center costs and the salaries and related costs of the Company’s operations group. This group sets up, initiates and monitors the Company’s advertising campaigns. In addition, amortization of acquired developed technology, depreciation of the data center equipment, rental payments to third-party vendors for data centers and amortization of capitalized internal-use software are included in other cost of revenue.

Research and Development—Research and development expenses include costs associated with the maintenance and ongoing development of the Company’s technology, including compensation and employee benefits and allocated costs associated with the Company’s engineering and research and development departments, as well as costs for contracted services and supplies. Allocated costs include charges for facilities, office expenses, telephones, and other miscellaneous expenses. The Company reviews costs incurred in the application development stage and assesses such costs for potential capitalization.

Sales and Marketing—Sales and marketing expenses consist primarily of compensation (including commissions) and employee benefits of sales and marketing personnel and related support teams, allocated costs, amortization of acquired intangible assets, certain advertising costs, travel, trade shows and marketing materials. Allocated costs include charges for facilities, office expenses, telephones, and other miscellaneous expenses. The Company incurred advertising costs of $6.0 million, $3.6 million and $0.1 million for the years ended December 31, 2014, 2013 and 2012, respectively.

General and Administrative—General and administrative expenses include facilities costs, executive and administrative compensation and employee benefits, depreciation, professional services fees, insurance costs, bad debt and other allocated costs, such as facility-related expenses, supplies and other fixed costs. Allocated costs include charges for facilities, office expenses, telephones, and other miscellaneous expenses.

Stock-based Compensation—The Company measures compensation expense for all stock-based payment awards, including stock options granted to employees, based on the estimated fair value of the awards on the date of the grant. The fair value of each stock option granted is estimated using the Black-Scholes option pricing model. Stock-based compensation is recognized on a straight-line basis over the requisite vesting period, net of estimated forfeitures. The forfeiture rate is based on an analysis of the Company’s actual historical forfeitures.

The Company accounts for stock options issued to non-employees based on the fair value of the awards determined using the Black-Scholes option pricing model.

Preferred Stock Warrant Liability—Free standing warrants related to shares that are redeemable or contingently redeemable were classified as a liability on the Company’s consolidated balance sheet. The fully-vested convertible preferred stock warrants were subject to re-measurement at each balance sheet date, and any change in fair value is recognized as a component of other expense, net. As completion of the Company’s initial public offering constituted a liquidation event, the convertible preferred stock warrants were converted into common stock or warrants to purchase common stock, and the liability was reclassified to additional paid-in capital in the third quarter of 2013.

Income Taxes—The Company accounts for income taxes using an asset and liability approach. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Operating loss and tax credit carry-forwards are measured by applying currently enacted tax laws. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized.

The Company recognizes the tax effects of an uncertain tax position only if it is more likely than not to be sustained based solely on its technical merits as of the reporting date, and then, only in an amount more likely than not to be sustained upon review by the tax authorities. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.

Recently Issued and Adopted Accounting Pronouncements—Under the Jumpstart Our Business Startups Act (the "JOBS Act"), we qualify as an “emerging growth company.” We have irrevocably elected to opt out of the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act, and, therefore, we will be subject to the same new or revised accounting standards as other public companies that are not “emerging growth companies.”

In May 2014, the FASB issued new accounting guidance related to revenue recognition. This new standard will replace all current U.S. GAAP guidance on this topic and eliminate all industry-specific guidance. The new revenue recognition standard provides a unified model to determine when and how revenue is recognized. The core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration for which the entity expects to be entitled in exchange for those goods or services. This guidance will be effective beginning January 1, 2017 and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. We have not yet determined if we will apply this new accounting standard retrospectively or as a cumulative-effect adjustment and are in the process of evaluating the impact of adopting this standard on our financial statements.

In August 2014, the FASB issued new guidance related to management responsibility to assess and provide related disclosure of the Company’s ability to continue as a going concern. This ASU will be effective for annual periods ending after December 15, 2016. The adoption of this guidance will not have a material impact on the Company's consolidated financial statements.

FAIR_VALUE_MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS
	NOTE 2.	FAIR VALUE MEASUREMENTS
	Fair value is defined as the price that would be received on the sale of an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants at the measurement date. The FASB has established a fair value hierarchy that distinguishes between (1) market participant assumptions developed based on market data obtained from independent sources (observable inputs) and (2) an entity’s own assumptions about market participant assumptions developed based on the best information available in the circumstances (unobservable inputs). The fair value hierarchy consists of three broad levels, which gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3).
	The three levels of the fair value hierarchy under the guidance for fair value measurement are described below:
	Level 1	Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. Pricing inputs are based upon quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. For securities, the valuations are based on quoted prices of the security that are readily and regularly available in an active market, and accordingly, a significant degree of judgment is not required. As of December 31, 2014 and 2013, the Company used Level 1 assumptions for its money market funds.
	Level 2	Pricing inputs are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by observable market data for substantially the full term of the assets or liabilities. As of December 31, 2014 and 2013, the Company did not have any Level 2 financial assets or liabilities.
	Level 3	Pricing inputs are generally unobservable for the assets or liabilities and include situations where there is little, if any, market activity for the investment. The inputs into the determination of fair value require management’s judgment or estimation of assumptions that market participants would use in pricing the assets or liabilities. The fair values are therefore determined using model-based techniques that include option pricing models, discounted cash flow models, and similar techniques. As of December 31, 2014 and 2013, the Company did not have any Level 3 financial assets or liabilities.
	The following tables set forth the Company’s financial instruments that were measured at fair value on a recurring basis as of December 31, 2014 and 2013, by level within the fair value hierarchy (in thousands):
	31-Dec-14		Fair Value		Level 1		Level 2		Level 3
	Money market funds (included in cash and cash equivalents)		$	22,904	$	22,904	$	—	$	—
	31-Dec-13		Fair Value		Level 1		Level 2		Level 3
	Money market funds (included in cash and cash equivalents)		$	2,900	$	2,900	$	—	$	—

PROPERTY_EQUIPMENT_AND_SOFTWAR

PROPERTY, EQUIPMENT AND SOFTWARE, NET	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
PROPERTY, EQUIPMENT AND SOFTWARE, NET
	NOTE 3.	PROPERTY, EQUIPMENT AND SOFTWARE, NET
	Property, equipment and software, net as of December 31, 2014 and 2013, consisted of the following (in thousands):
		December 31,
		2014			2013
	Capitalized internal-use software costs	$	23,385		$	14,030
	Computer hardware and software	46,299			17,077
	Furniture and fixtures	11,674			1,735
	Leasehold improvements	36,811			815
	Construction in progress	—			3,622
	Total	118,169			37,279
	Accumulated depreciation and amortization	(28,728		)	(11,485		)
	Total property, equipment and software, net	$	89,441		$	25,794
	Total depreciation and amortization expense, excluding amortization of internal-use software costs, was $13.1 million, $4.5 million and $1.3 million for the years ended December 31, 2014, 2013 and 2012, respectively. Amortization expense of internal-use software costs was $5.2 million, $3.4 million and $2.3 million for the years ended December 31, 2014, 2013 and 2012, respectively. Refer to Note 7 for details of the Company's capital leases as of December 31, 2014 and 2013.

BUSINESS_COMBINATIONS_BUSINESS

BUSINESS COMBINATIONS BUSINESS COMBINATIONS	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
BUSINESS COMBINATION
	NOTE 4.	BUSINESS COMBINATIONS
	On September 5, 2014, the Company acquired X Plus Two Solutions, Inc., a Delaware corporation (“X Plus Two”), which wholly owns X Plus One Solutions, Inc, known in the industry as [x+1] ("[x+1]"). The acquisition of [x+1] significantly expands the market opportunity and accelerates the Company’s entry into the digital marketing enterprise software-as-a-service ("SaaS") market. At closing, all outstanding shares of [x+1]'s capital stock and stock options were canceled in exchange for an aggregate of $98.0 million in cash and 5,253,084 shares of the Company’s common stock. The total preliminary purchase consideration is as follows (in thousands):
	Purchase consideration:
	Cash	$	98,045
	Fair value of 5,253,084 shares common stock transferred	82,421
	Total preliminary purchase price	$	180,466
	The acquisition of [x+1] was accounted for in accordance with the acquisition method of accounting for business combinations with the Company as the accounting acquirer. The Company expensed the acquisition-related transaction costs in the amount of $4.9 million in general and administrative expenses. The total purchase price as shown in the table above is allocated to the tangible and identifiable intangible assets acquired and liabilities assumed based on their estimated fair values. The total purchase price was allocated using the information currently available for asset acquired and liabilities assumed and may be revised when these estimates change (in thousands):
	Current assets	$	32,005
	Non-current assets	3,999
	Current liabilities	(28,893		)
	Non-current liabilities	(16,216		)
	Net acquired tangible assets	(9,105		)
	Identifiable intangible assets	74,700
	Goodwill	114,871
	Total preliminary purchase price	$	180,466
	The goodwill is primarily attributable to synergies expected to be generated from combining the Company's and [x+1]’s technology and operations. None of the goodwill recorded as part of the acquisition will be deductible for U.S. federal income tax purposes.
	The changes in the carrying amount of goodwill for the year ended December 31, 2014 is as follows (in thousands):
		Goodwill
	Balance as of December 31, 2013	$	—
	Goodwill acquired	114,871
	Goodwill adjustments (1)	541
	Balance as of December 31, 2014	$	115,412
	(1) Pursuant to business combinations accounting guidance, goodwill adjustments, for the effect of changes to net assets acquired during the measurement period, may be recorded up to one year from the date of an acquisition. Goodwill adjustments were not significant to our previously reported operating results or financial position.
	The preliminary estimated useful life and fair values of the identifiable intangible assets as of December 31, 2014 were as follows (in thousands):
								As of December 31, 2014
		Estimated Useful Life (in years)		Preliminary Fair Value				Accumulated Amortization			Net Book Value
				(in thousands)
	Developed technology	4-Mar		$	42,100			$	(3,703	)	$	38,397
	Customer relationships	8-Jul		27,700				(1,107		)	26,593
	Trademarks	5		2,000				(128		)	1,872
	Non-compete agreements	2		2,900				(463		)	2,437
	Total			$	74,700			(5,401		)	69,299
	Amortization expense of intangible assets for the year ended December 31, 2014 was 5.4 million. The expected annual amortization expense of intangible assets as of December 31, 2014 is presented below (in thousands):
	Year ending December 31,		Amortization
	2015		$	16,908
	2016		16,445
	2017		14,095
	2018		8,851
	2019		3,738
	Thereafter		9,262
	Total		$	69,299
	The results of operations of [x+1] have been included in the Company's consolidated statements of operations from the acquisition date. The following unaudited pro forma condensed combined financial information reflects the Company's condensed results of operations for the periods indicated and assumes that the business had been acquired at the beginning of fiscal year 2013 and includes pro forma adjustments. Direct and incremental transaction costs are excluded from the year ended December 31, 2014 and included in the year ended December 31, 2013. The pro forma results also include amortization associated with the acquired intangible assets and the associated tax impact on these unaudited pro forma adjustments. The tax benefit of $4.2 million that resulted from the acquisition is recorded in the year ended December 31, 2013. The pro forma results are presented for informational purposes only and are not necessarily indicative of results that would have occurred had the acquisition taken place at the beginning of the earliest period presented, or of future results (in thousands):
		Years ended December 31,
		2014				2013
	Pro forma revenue	$	468,881			$	310,469
	Pro forma net loss	$	(78,312	)		$	(50,666	)

ACCRUED_AND_OTHER_CURRENT_LIAB

ACCRUED AND OTHER CURRENT LIABILITIES	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
ACCRUED AND OTHER CURRENT LIABILITIES
	NOTE 5.	ACCRUED AND OTHER CURRENT LIABILITIES
	Accrued and other current liabilities as of December 31, 2014 and 2013 consisted of the following (in thousands):
		December 31,
		2014		2013
	Payroll and benefit related expenses	$	16,379	$	15,476
	Other accrued expenses	16,879		6,108
	Total accrued and other current liabilities	$	33,258	$	21,584

CAPITAL_LEASES

CAPITAL LEASES	12 Months Ended
	Dec. 31, 2014
Leases [Abstract]
CAPITAL LEASES
	NOTE 6.	CAPITAL LEASES
	Property and equipment at December 31, 2014 and 2013 included $19.2 million and $0.6 million, respectively, acquired under capital lease agreements of which the majority consists of computer hardware.
	The remaining future minimum lease payments under these non-cancelable capital leases as of December 31, 2014 were as follows (in thousands):
	Year ending December 31,		Future Payments
	2015		$	6,354
	2016		6,412
	2017		4,726
	2018		2,016
	2019		57
	Thereafter		—
	Total minimum lease payments		$	19,565
	Less: amount representing interest and taxes		(1,742		)
	Less: current portion of minimum lease payments		(5,482		)
	Capital lease obligations, net of current portion		$	12,341

OTHER_INCOME_EXPENSENET

OTHER INCOME (EXPENSE)—NET	12 Months Ended
	Dec. 31, 2014
Other Income and Expenses [Abstract]
OTHER INCOME (EXPENSE)—NET
	NOTE 7.	OTHER INCOME (EXPENSE)—NET
	Other income (expense)—net for the years ended December 31, 2014, 2013 and 2012, consisted of the following (in thousands):
		Years ended December 31,
		2014			2013			2012
	Gain (loss) on foreign currency transactions	$	(5,259	)	$	(205	)	$	43
	Other non-operating income (loss), net	(8		)	(103		)	92
	Total other income (expense)—net	$	(5,267	)	$	(308	)	$	135

DEBT

DEBT	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
DEBT
	NOTE 8.	DEBT
	Loan Facility—On December 31, 2014, the Company entered into a Second Amended and Restated Revolving Credit and Term Loan Agreement with certain lenders, the ("2014 Loan Facility"), which was last amended on March 13, 2015. The 2014 Loan Facility amended and restated the Company's then-existing Loan and Security Agreement, dated as of April 7, 2010, (as amended, the "2010 Loan Facility"). The 2014 Loan Facility provides for an $80.0 million revolving credit facility which matures on December 31, 2017, with a $12.0 million letter of credit subfacility and a $2.5 million swingline subfacility, and a $30.0 million secured term loan that matures on December 31, 2019. Revolving loans may be advanced under the 2014 Loan Facility in amounts up to the lesser of (i) 85% of eligible accounts receivable and (ii) $80.0 million, less the then outstanding principal amount of the term loan. If at any time the aggregate amounts outstanding exceed the allowable maximum advance , then the Company must make a repayment in an amount sufficient to eliminate the excess.
	If the aggregated cash balances on deposit with the lenders and certain other domestic financial institutions fall below $40.0 million, the lenders have the right to use future cash collections from accounts receivable directly to reduce the outstanding balance of the revolving credit facility. The Company is also obligated to prepay the term loan with proceeds from the occurrence of certain events. The Company may repay revolving loans and term loans under the 2014 Loan Facility in whole or in part at any time without premium or penalty, subject to certain conditions.
	As of December 31, 2014, $30.0 million in term loans, $40.0 million under the revolving credit facility and letters of credit in the amount of $6.0 million were outstanding. The term loan will be repaid in quarterly principal installments of $1.5 million. The Company paid customary closing fees and pays customary commitment fees and letter of credit fees.
	Revolving loans bear interest, at the Company's option, at (i) a base rate determined pursuant to the terms of the 2014 Loan Facility, plus a spread of 1.625% to 2.125%, or (ii) a LIBOR rate determined pursuant to the terms of the Loan Facility, plus a spread of 2.625% to 3.125%. Term loans bear interest, at the Company's option, at (i) a base rate determined pursuant to the terms of the Loan Facility, plus a spread of 2.50% to 3.00%, or (ii) a LIBOR rate determined pursuant to the terms of the Loan Facility, plus a spread of 3.50% to 4.00%. In each case, the spread is based on the cash reflected on the Company’s balance sheet for the preceding fiscal quarter, plus an amount equal to the average unused portion of the revolving credit commitments during such fiscal quarter. The base rate is determined as the highest of (i) the prime rate announced by Comerica Bank, (ii) the federal funds rate plus a margin equal to 1.00% and (iii) the daily adjusted LIBOR rate plus a margin equal to 1.00%. Under certain circumstances, a default interest rate of 2.00% above the applicable interest rate will apply on all obligations during the existence of an event of default under the 2014 Loan Facility.
	The Company is required to maintain a minimum of $30.0 million of cash on deposit with the lenders and comply with certain financial covenants under the 2014 Loan Facility, including the following:
	EBITDA. The Company is required to maintain specified EBITDA , which is defined for this purpose, with respect to any trailing twelve month period, as an amount equal to the sum of (i) consolidated net income (loss) in accordance with GAAP, after eliminating all extraordinary nonrecurring items of income, plus (ii) depreciation and amortization; income tax expense; total interest expense; non-cash expenses or losses; stock-based compensation expense; costs and expenses from permitted acquisitions up to certain limits; costs and expenses in connection with the 2014 Loan Facility up to certain limits; certain legal fees up to certain limits incurred through December 2015; integration costs related to the [x+1] acquisition up to certain limits incurred through December 31, 2014 and any other expenses agreed with Comerica and the lenders; less (iii) all extraordinary and non-recurring revenues and gains (including income tax benefits).
	Liquidity ratio. Under the Loan Facility, the ratio of (i) the sum of all cash on deposit with Comerica and certain other domestic financial institutions and the aggregate amount of all eligible accounts receivable to (ii) all indebtedness owing to the lenders under the 2014 Loan Facility must be at least 1.10 to 1.00.
	The terms of the 2014 Loan Facility also require the Company to comply with certain other financial and non-financial covenants. As of December 31, 2014, the Company was in compliance with all covenants.
	Future Payments
	Future principal payments of long-term debt as of December 31, 2014 were as follows (in thousands):
	Year ending December 31,		Future Payments
	2015		$	6,000
	2016		6,000
	2017		6,000
	2018		6,000
	2019		6,000
	Total		30,000
	Less: current portion of long-term debt		(6,000		)
	Long-term debt, net of current portion		$	24,000
	As of December 31, 2014, the $40.0 million balance outstanding under the revolving credit facility had a maturity date of December 31, 2017, and because the Company has the option to draw upon the facility or repay borrowed funds at any time, the balance is shown as a current liability in the accompanying consolidated balance sheet. The debt on the consolidated balance sheet are shown net of $1.0 million in debt issuance costs.
	Debt of $11.1 million that was assumed with the acquisition of [x+1] on September 5, 2014 was paid in full immediately following the closing of the merger in September 2014.

STOCKHOLDERS_EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY
	NOTE 9.	STOCKHOLDERS’ EQUITY
	In February 2014, the Company completed an underwritten follow-on public offering of its common stock in which 2,000,000 shares of common stock were sold by the Company and 3,000,000 shares of common stock were sold by selling stockholders. The public offering price of the shares sold in the offering was $61.00 per share. The Company did not receive any proceeds from the sale of shares by the selling stockholders. The total gross proceeds from the offering to the Company were $122.0 million. After deducting underwriters’ discounts and commissions and offering expenses, the aggregate net proceeds received by the Company totaled $115.4 million.
	On September 5, 2014, the Company acquired X Plus Two, which wholly owns [x+1], for 5,253,084 shares of the Company’s common stock and $98.0 million in cash.
	As of December 31, 2014 and 2013, 1,000,000,000 shares of common stock with $0.001 par value was authorized, of which 42,002,533 and 32,825,992 shares were issued and outstanding as of December 31, 2014 and 2013, respectively. As of December 31, 2014 and 2013, 100,000,000 shares of undesignated preferred stock were authorized, of which no shares were issued or outstanding.
	Reserved Shares of Common Stock—The Company’s shares of capital stock reserved for issuance under the Company's equity incentive plans as of December 31, 2014 were as follows:
		31-Dec-14
	Options outstanding	6,290,519
	Restricted stock awards and units outstanding	2,507,523
	Available for future stock option and restricted stock unit grants	3,688,676
	Available for future employee stock purchase plan purchases	1,286,532
	Total shares reserved	13,773,250
	2008 Equity Incentive Plan—The 2008 Equity Incentive Plan (the “2008 Plan”) provides for the grant of incentive stock options and nonqualified stock options. The compensation committee of the Company's board of directors has the authority to approve the employees and non-employees to whom options are granted and determine the terms of each option, including (i) the number of shares of common stock subject to the option; (ii) when the option becomes exercisable; (iii) the option exercise price, which, in the case of incentive stock options, must be at least 100% of the fair market value of the common stock as of the date of grant; and (iv) the duration of the option (which, in the case of incentive stock options, may not exceed 10 years). Options granted under the 2008 Plan generally vest over four years and expire no later than 10 years from the date of grant. The Company has terminated the 2008 Plan for future use, and no further equity awards are to be granted under the 2008 Plan. All outstanding awards under the 2008 Plan will continue to be governed by their existing terms.
	Under the terms of the 2008 Plan, certain employees received the right to exercise unvested options. Upon termination of service, an employee’s unvested shares may be repurchased by the Company at the original purchase price. As of December 31, 2014 and 2013, 98,787 and 315,579 unvested shares, respectively, were subject to repurchase. During the years ended December 31, 2014 and 2013, the Company repurchased 25,625 and 5,834 shares of unvested stock, respectively.
	2013 Equity Incentive Plan—Since its initial public offering in September 2013, the Company has made equity grants pursuant to its 2013 Equity Incentive Plan (the “2013 Plan”). The 2013 Plan permits the grant of incentive stock options to the Company’s employees and any parent and subsidiary corporations’ employees, and the grant of nonstatutory stock options, restricted stock, restricted stock units, stock appreciation rights, performance units and performance shares to the Company’s employees, directors and consultants and the Company’s parent and subsidiary corporations’ employees and consultants.
	A total of 5,000,000 shares of common stock were reserved for issuance upon initial adoption of the 2013 Plan. In addition, the shares to be reserved for issuance under the 2013 Plan will also include shares subject to stock options or similar awards granted under the 2008 Plan that expire or terminate without having been exercised in full and shares issued pursuant to awards granted under the 2008 Plan that are forfeited to or repurchased by the Company, provided that the maximum number of shares that may be added to the 2013 Plan pursuant to this provision is 7,900,000 shares.
	The number of shares available for issuance under the 2013 Plan also includes an annual increase on the first day of each fiscal year equal to the least of (i) 4,000,000 shares; (ii) 5% of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (iii) such other amount as the Company’s board of directors may determine. Effective January 1, 2014 and 2015, 1,641,299 and 2,100,126 shares, respectively, were added to the shares reserved for issuance under the 2013 Plan according to the terms described above.
	The compensation committee of the board of directors has the authority to approve the employees and other service providers to whom equity awards are granted and to determine the terms of each award, subject to the terms of the 2013 Plan. The compensation committee may determine the number of shares subject to an award, except that awards to non-employee members of the board of directors are determined under the Company's Outside Director Compensation Policy. Options and stock appreciation rights granted under the 2013 Plan must have a per share exercise price equal to at least 100% of the fair market value of a shares of the Company's common stock as of the date of grant and may not expire later than 10 years from the date of grant.
	The following tables summarize option award activity:
		Number of		Weighted-				Weighted-	Aggregate
		Options		Average				Average	Intrinsic Value
		Outstanding		Exercise				Remaining	(in thousands)
				Price				Contractual
								Life
								(Years)
	Balance at December 31, 2013	7,410,588		$	6.97			8.5	$	404,106
	Options granted (weighted average fair value of $17.73 per share)	892,908		32.43
	Options exercised	-1,499,190		2.53
	Options forfeited	-513,787		12.59
	Balance at December 31, 2014	6,290,519		$	11.18			7.8	$	46,926
	Options vested and expected to vest—December 31, 2014	5,975,101		$	10.82			7.8	$	45,768
	Options vested and exercisable—December 31, 2014	3,249,674		$	6.59			7.3	$	31,934
	Aggregate intrinsic value represents the difference between the Company’s fair value of its common stock and the exercise price of outstanding in-the-money options. The total intrinsic value of options exercised was approximately $38.1 million, $11.9 million and $1.1 million for the years ended December 31, 2014, 2013 and 2012, respectively.
	As of December 31, 2014, 2013 and 2012, unamortized stock-based compensation expense related to unvested common stock options was $25.4 million, $21.7 million and $12.5 million, respectively. The weighted-average period over which such stock-based compensation expense will be recognized is approximately 2.3 years.
	Restricted Stock Units ("RSUs") and Restricted Stock Awards ("RSAs")—A summary of RSU and RSA activity for the year ended December 31, 2014 is as follows:
		Number of Shares			Weighted Average Grant Date Fair Value
	Unvested at December 31, 2013	382,402			$	55.86
	Granted	2,382,180			20.4
	Vested and issued	(110,359	)		51.29
	Canceled	(138,912	)		42.7
	Unvested at December 31, 2014	2,515,311			$	23.2
	The total intrinsic value of RSUs and RSAs vested and issued during the year ended December 31, 2014 was approximately $2.3 million.
	At December 31, 2014, unrecognized compensation expense related to the RSUs and RSAs was $43.8 million. The unrecognized compensation expense will be amortized on a straight-line basis through 2019. The total fair value of RSUs and RSAs vested and issued during the year ended December 31, 2014 was $2.3 million.
	Employee Stock Purchase Plan—In August 2013, the Company’s board of directors adopted and the stockholders approved the Company’s 2013 Employee Stock Purchase Plan (the “ESPP”), which became effective upon adoption by the Company’s board of directors. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The offering periods generally start on the first trading day on or after June 1 and December 1 of each year and end on the first trading day on or before November 30 and May 31 approximately six months later. The administrator may, in its discretion, modify the terms of future offering periods. Due to the timing of the Company's initial public offering, the first offering period started on October 1, 2013 and ended on May 31, 2014. At the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period. As of December 31, 2014, total compensation costs related to outstanding rights to purchase shares of common stock under the ESPP offering period ending on the first trading day on or before May 31, 2015, were approximately $1.6 million, which will be recognized over the offering period.
	Employee Stock-based Compensation—The fair value of options on the date of grant is estimated based on the Black-Scholes option-pricing model using the single-option award approach with the weighted-average assumptions set forth below. Expected term represents the period that the Company’s stock-based awards are expected to be outstanding and is determined based on the simplified method. Due to the lack of historical exercise activity for the Company, the simplified method calculates the expected term as the mid-point between the vesting date and the contractual expiration date of the award. Volatility is estimated using comparable public company volatility for similar option terms until a sufficient amount of historical information regarding the volatility of the Company's share price becomes available. The risk-free interest rate is determined using a U.S. Treasury rate for the period that coincides with the expected term. As the Company has never paid cash dividends, and at present, has no intention to pay cash dividends in the future, expected dividends are zero. Expected forfeitures are based on the Company’s historical experience. The fair value of restricted stock unit awards is the grant date closing price of the Company's common stock.
	The Company uses the straight-line method for expense recognition over the vesting period of the award or option.
	The assumptions used to value options granted to employees were as follows:
		Years ended December 31,
		2014		2013		2012
	Expected term (years)	5.5–6.3		5.3–6.6		5.3–7.3
	Volatility	55.6%–59.5%		53.8%–64.9%		61.2%–63.4%
	Risk-free interest rate	1.84%–1.97%		1.04%–1.88%		0.70%–1.21%
	Dividend yield	—		—		—
	The assumptions used to calculate our stock-based compensation for each stock purchase right granted under the ESPP were as follows:
		Years ended December 31,
		2014		2013
	Expected term (years)	0.5–0.7		0.7
	Volatility	66.2%–77.4%		66.20%
	Risk-free interest rate	0.06%–0.08%		0.07%
	Dividend yield	—		—
	Equity compensation allocation
	The following table summarizes the allocation of stock-based compensation in the accompanying consolidated statements of operations (in thousands):
		Years ended December 31,
		2014				2013			2012
Other cost of revenue	$	1,758			$	471		$	37
Research and development	5,039				2,308			734
Sales and marketing	10,372				4,482			1,100
General and administrative	6,361				3,581			1,450
Total	$	23,530			$	10,842		$	3,321

NET_INCOME_LOSS_PER_SHARE

NET INCOME (LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
NET INCOME (LOSS) PER SHARE
	NOTE 10.	NET LOSS PER SHARE
	The Company calculates its basic and diluted net loss per share attributable to common stockholders in conformity with the two-class method required for companies with participating securities. Under the two-class method, in periods when the Company has net income, net income attributable to common stockholders is determined by allocating undistributed earnings, calculated as net income less current period convertible preferred stock non-cumulative dividends, between common stock and convertible preferred stock. In computing diluted net income attributable to common stockholders, undistributed earnings are re-allocated to reflect the potential impact of dilutive securities. The Company’s basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period. The diluted net loss per share attributable to common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. For purposes of this calculation, convertible preferred stock, options to purchase common stock and preferred stock warrants are considered common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is antidilutive.
	Basic loss per share is calculated by dividing net loss by the weighted-average number of shares of common stock outstanding during the period, less shares subject to repurchase, and excludes any dilutive effects of employee stock-based awards and warrants. Because the Company had net losses for the years ended December 31, 2014, 2013 and 2012, all potential shares of common stock were determined to be anti-dilutive.
	The following table sets forth the computation of net loss per share of common stock (in thousands, except per share amounts):
		Years ended December 31,
		2014				2013			2012
	Net loss	$	(64,311	)		$	(20,932	)	$	(10,343	)
	Weighted-average shares used to compute basic and diluted net loss per share	37,001				15,177			8,024
	Basic and diluted net loss per share	$	(1.74	)		$	(1.38	)	$	(1.29	)
	The following securities were excluded from the calculation of diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented (in thousands):
		Years ended December 31,
		2014			2013			2012
	Convertible preferred stock	—			—			19,479
	Employee stock options	6,291			7,409			5,830
	Shares subject to repurchase	99			316			—
	Restricted stock units (RSUs) and restricted stock awards (RSAs)	2,508			383			—
	Employee stock purchase plan	58			58			—
	Convertible preferred stock warrants	—			—			267
		8,956			8,166			25,576

INCOME_TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
INCOME TAXES
	NOTE 11.	INCOME TAXES
	The Company recorded an income tax benefit of $4.2 million and income tax provision of $0.3 million and$0.1 million for the years ended December 31, 2014, 2013 and 2012, respectively. The tax benefit for the year ended December 31, 2014 is primarily due to a partial release of valuation allowance against the Company’s deferred tax assets as a result of net deferred tax liabilities generated from intangibles acquired from the [x+1] acquisition. The tax expense for the years ended December 31, 2013 and 2012 is primarily due to foreign and state income tax expense.
	The following table presents domestic and foreign components of income (loss) before income taxes for the periods presented (in thousands):
		Years ended December 31,
		2014				2013				2012
	Domestic	$	(70,438	)		$	(21,568	)		$	(10,637	)
	International	1,888				921				378
	Total	$	(68,550	)		$	(20,647	)		$	(10,259	)
	The components of the income tax (benefit) for income taxes were as follows (in thousands):
		Years ended December 31,
		2014				2013				2012
	Current:
	Federal	$	—			$	—			$	—
	State	9				(4		)		11
	Foreign	1,159				289				73
	Deferred:
	Federal	(4,042		)		—				—
	State	(713		)		—				—
	Foreign	(652		)		—				—
	Total benefit (provision) for income taxes	$	(4,239	)		$	285			$	84
	The following table presents a reconciliation of the statutory federal rate to the Company’s effective tax rate for the periods presented:
		Years ended December 31,
		2014			2013			2012
	Tax benefit at federal statutory rate	34	%		34	%		34	%
	State income taxes, net of federal effect	6.17			0.01			(0.07	)
	Foreign rate differential	0.2			0.12			0.54
	Change in valuation allowance	(31.94	)		(28.42	)		(25.16	)
	Meals and entertainment	(1.44	)		(2.07	)		(1.98	)
	Warrant liability	—			(7.81	)		(7.65	)
	Research credits	2.86			2.79			—
	Transaction costs	(2.24	)		—			—
	Other	(1.41	)		—			(0.50	)
	Total provision	6.2	%		(1.38	)%		(0.82	)%
	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The following table presents the significant components of the Company’s deferred tax assets and liabilities for the periods presented (in thousands):
		December 31,
		2014				2013
	Deferred tax assets:
	Tax credit carry-forwards	$	6,877			$	2,256
	Net operating loss carry-forwards	45,281				13,118
	Charitable contributions	323				133
	Accrued liabilities and allowances	18,171				5,421
		70,652				20,928
	Deferred tax liability:
	Depreciation and amortization	(32,194		)		(5,166		)
		(32,194		)		(5,166		)
	Net deferred tax assets before valuation allowance	$	38,458			$	15,762
	Valuation allowance	(38,159		)		(15,762		)
	Net deferred tax assets (liabilities)	$	299			$	—
	A valuation allowance is provided for net deferred tax assets where the recoverability of the assets is uncertain. The determination to provide a valuation allowance is dependent upon the assessment of whether it is more likely than not that sufficient future taxable income will be generated to utilize the deferred tax assets. Based on the weight of the available evidence, which includes the Company’s historical operating losses, lack of taxable income and the accumulated deficit, the Company provided a full valuation allowance against the U.S federal and state deferred tax assets resulting from the tax loss and credits carried forward. The valuation allowance increased by $22.4 million and $6.9 million during the years ended December 31, 2014 and 2013, respectively. The change in valuation allowance is mainly attributable to the increase in deferred tax assets due to the current year taxable loss, deductible temporary differences and research credits, and net deferred tax liabilities due to the [x+1] acquisition. As a result of the [x+1] acquisition, the Company acquired a net deferred tax liability of $4.0 million which served to reduce the Company’s net deferred tax assets by a similar amount. Accordingly, the Company adjusted its valuation allowance by the same amount to continue to reserve against its net deferred tax assets. The corresponding decrease in valuation allowance was recorded as a tax benefit during the quarter ended September 30, 2014.
	As of December 31, 2014, the Company had $0.3 million of net deferred tax assets related to deductible foreign stock compensation which it expects to realize in future foreign tax filings.
	As of December 31, 2014, the Company had net operating loss carry-forwards of approximately $55.3 million for federal income taxes, which expire beginning in 2020 and $5.2 million operating loss carry-forwards for state income taxes which expire beginning in 2020. Internal Revenue Code Section 382 limits the use of net operating loss and tax credit carryforwards in certain situations where changes occur in the stock ownership of a company. If the Company experiences a change of ownership, then utilization of the net operating loss and tax credit carry-forwards may be restricted.
	The 2014 Tax Increase Prevention Act ("TIPA") was signed into law on December 19, 2014, extending the federal research and development credits for amounts incurred from January 1, 2014 through December 31, 2014. As a result of the extension, a federal tax credit of $3.5 million, was generated in 2014 which was fully offset by valuation allowance.
	As of December 31, 2014, the Company had federal and California state research and development tax credits of $7.6 million and $2.7 million, respectively. If not utilized, the federal carry forwards will begin to expire in various amounts beginning in 2020. The state tax credit can be carried forward indefinitely.
	ASC 740-10 requires that the tax effects of a position be recognized only if it is "more likely than not" to be sustained based solely on its technical merits as of the reporting date. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.
	The Company does not provide for federal income taxes on the undistributed earnings of its foreign subsidiaries as such earnings are determined to be reinvested indefinitely. Upon distribution of those earnings in the form of dividends or otherwise, the Company may be subject to U.S. federal and state income taxes, the determination of which is not practical as it is dependent on the amount of U.S. tax losses or other tax attributes available at the time of repatriation. As of December 31, 2014, undistributed earnings of the Company's foreign subsidiaries amounted to approximately $2.3 million.
	The federal and state net operating loss carryforwards include excess tax benefits from stock option exercises of $15.2 million and $0.7 million, respectively. An increase to additional paid-in capital for the excess tax benefits would not be recognized until that deduction reduces income tax payable.
	The table below provides a reconciliation of the beginning and ending amount of unrecognized tax benefits (excluding interest and penalties), related to uncertain tax positions, for the years ended December 31, 2014, 2013 and 2012 (in thousands):
		Years ended December 31,
		2014				2013				2012
	Unrecognized benefit—beginning of period	$	669			$	272			$	184
	Gross increases—prior year tax positions	46				126				10
	Gross increases—current year tax positions	2,749				271				78
	Unrecognized benefit—end of period	$	3,464			$	669			$	272
The unrecognized tax benefits of $3.5 million as of December 31, 2014 would have no impact on the Company’s effective tax rate if recognized because the Company may fully reserve such tax benefits due to the Company’s current assessment with regard to its ability to utilize any such future tax benefits.
At December 31, 2014, the Company had no cumulative interest and penalties related to the uncertain tax position.
The Company is currently unaware of any uncertain tax positions that could result in significant additional payments, accruals, or other material deviation in this estimate over the next twelve months.
The Company files income tax returns in the United States, various states, and certain foreign jurisdictions. As a result of net operating loss carryforwards, all of our tax years are open to federal and state examination in the United States. Tax years from 2011 are open to examination in various foreign countries.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES
	NOTE 12.	COMMITMENTS AND CONTINGENCIES
	Operating Leases—The Company has operating lease agreements for office space for administration, research and development and sales and marketing activities in the United States that expire at various dates through 2025.
	The Company recognizes rent expense on a straight-line basis over the lease term and records the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. Rent expense was $14.7 million, $4.3 million and $1.6 million for the years ended December 31, 2014, 2013 and 2012, respectively.
	Approximate remaining future minimum cash lease payments under these non-cancelable operating leases as of December 31, 2014 were as follows (in thousands):
	Year ending December 31,		Future Payments
	2015		$	18,283
	2016		20,318
	2017		19,877
	2018		18,592
	2019		21,024
	Thereafter		44,882
			$	142,976
	Please refer to Note 6 for details of the Company's capital lease commitments as of December 31, 2014.
	Letters of Credit Bank Guarantees and Restricted Cash—As of December 31, 2014 and 2013, the Company had irrevocable letters of credit outstanding, with all financial institutions, in the amount of $6.8 million and $3.4 million, respectively, for facilities leases. The letters of credit have various expiration dates, with the latest being June 2025.
	As of December 31, 2014, the Company had $2.9 million in cash reserved to support bank guarantees for certain office lease agreements. These amounts are classified as restricted cash on the Company's consolidated balance sheets.
	Indemnification Agreements—In the ordinary course of business, the Company enters into agreements providing for indemnification of varying scope and terms to customers, vendors, lessors, business partners, and other parties with respect to certain matters, including, but not limited to, losses arising out of breach of such agreements, services to be provided by the Company or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with directors and certain officers and employees that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. No demands have been made upon the Company to provide indemnification under such agreements, and thus there are no claims that the Company is aware of that could have a material effect on the Company’s consolidated balance sheets, consolidated statements of operations, consolidated statements of comprehensive loss, or consolidated statements of cash flows.
	Legal Proceedings—The Company is involved from time to time in claims, proceedings, and litigation, including the following:
	On September 3, 2014 and September 10, 2014, respectively, two purported class actions were filed in the Northern District of California against the Company and certain of the Company’s officers and directors. The actions are Shah v. Rocket Fuel Inc., et al., Case No. 4:14-cv-03998, and Mehrotra v. Rocket Fuel Inc., et al., Case No. 4:14-cv-04114. The underwriters of the Company’s IPO on September 19, 2013 and its Secondary Offering on February 5, 2013 are also named as defendants. The complaints allege that the defendants made false and misleading statements about the ability of the Company’s technology to detect and eliminate fraudulent web traffic, and about the Company's future prospects. The complaints also allege that the Company’s registration statements and prospectuses for the IPO and the Secondary Offering contained false and misleading statements on these topics. The complaints purport to assert claims for violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 and SEC Rule 10b-5, and for violations of Sections 11 and 15 of the Securities Act of 1933, on behalf of those who purchased the Company’s common stock between September 20, 2013 and August 5, 2014, inclusive, as well as those who purchased stock in the Company’s initial public offering on September 19, 2013. The Mehrotra complaint also purports to assert a claim for violation of Section 12(a)(2) of the Securities Act of 1933. The complaints seek monetary damages in an unspecified amount. The above actions were consolidated and a lead plaintiff was selected on December 15, 2014. A consolidated complaint was filed on February 27, 2015. The Company intends to vigorously defend itself against the purported class action.
	The outcomes of the Company's legal proceedings are inherently unpredictable, subject to significant uncertainties, and could be material to its consolidated financial position, results of operations or cash flows by an unfavorable resolution of these actions. We cannot currently estimate a reasonably possible range of loss for these actions.
	Legal fees are expensed in the period in which they are incurred.

SEGMENTS

SEGMENTS	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
SEGMENTS
	NOTE 13.	SEGMENTS
	The Company considers operating segments to be components of the Company's business for which separate financial information is available that is evaluated regularly by the Company’s chief operating decision maker in deciding how to allocate resources and in assessing performance. The chief operating decision maker for the Company is the Chief Executive Officer. The Chief Executive Officer reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company has one business activity, and there are no segment managers who are held accountable for operations, operating results or plans for levels or components below the consolidated unit level. Accordingly, the Company has determined that it has a single operating and reportable segment.
	The following table summarizes total revenue generated through sales personnel located in the respective locations (in thousands):
		Years ended December 31,
		2014		2013		2012
	North America	$	349,289	$	213,601	$	96,289
	All Other Countries	59,352		27,004		10,300
	Total revenue	$	408,641	$	240,605	$	106,589
	The following table summarizes total long-lived assets in the respective locations (in thousands):
		December 31,
		2014		2013
	North America	$	85,355	$	23,956
	All Other Countries	4,086		1,838
	Total long-lived assets	$	89,441	$	25,794
	With respect to revenue concentration, the Company defines a customer as an advertiser that is a distinct source of revenue and is legally bound to pay for the advertising services that the Company delivers on the advertiser’s behalf. The Company counts all advertisers within a single corporate structure as one customer even in cases where multiple brands, branches or divisions of an organization enter into separate contracts with the Company. During the years ended December 31, 2014, 2013 and 2012, no single customer represented 10% or more of revenue.
	The Company also monitors the percentage of revenue from advertising agencies, even though advertising agencies that act on behalf of the Company’s advertisers are not considered customers based on the definition above. If all branches and divisions within each global advertising agency were considered to be a single agency for this purpose, two agency holding companies would have been associated with 10% or more of revenue during the years ended December 31, 2014 and 2013 and three agency holding companies would have been associated with 10% or more of revenue during the year ended December 31, 2012.

SUBSEQUENT_EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
SUBSEQUENT EVENTS
	NOTE 14.	SUBSEQUENT EVENTS
	On March 13, 2015, the Company entered into an amendment to its 2014 Loan Facility that, among other things, changed the minimum EBITDA covenant, removed the fixed charge ratio as a covenant for future quarters, set lower limits for capital expenditures, changed the definition of the borrowing base such that the revolving credit facility's borrowing base is reduced by the outstanding balance of the term loan. In addition, if the aggregated cash balances on deposit with the lenders and certain other domestic financial institutions fall below $40.0 million, the lenders have the right to use future cash collections from accounts receivable directly to reduce the outstanding balance of the revolving credit facility. See Note 8 for details about the 2014 Loan Facility.

NATURE_OF_BUSINESS_AND_SUMMARY1

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation	Principles of Consolidation—The consolidated financial statements include the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates—The preparation of consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Such estimates include, but are not limited to, provisions for doubtful accounts, the amount of software development costs which should be capitalized, future taxable income, the useful lives of long-lived and intangible assets and the assumptions used for purposes of determining stock-based compensation. Actual results could differ from those estimates.
Foreign Currency Translation	Foreign Currency Translation—The Company’s foreign subsidiaries record their assets, liabilities and results of operations in their local currencies, which are their functional currencies. The Company translates its subsidiaries' consolidated financial statements into U.S. dollars each reporting period for purposes of consolidation.
	Assets and liabilities of the Company’s foreign subsidiaries are translated at the period-end currency exchange rates, certain equity accounts are translated at historical exchange rates and revenue, expenses, gains and losses are translated at the average currency exchange rates in effect for the period. The effects of these translation adjustments are reported in a separate component of stockholders’ equity titled accumulated other comprehensive loss.
Fair Value of Financial Instruments	Fair Value of Financial Instruments—The Company’s financial instruments consist principally of cash equivalents, accounts receivable, accounts payable, term debt and revolving credit facilities. The fair value of the Company’s cash equivalents is determined based on quoted prices in active markets for identical assets for its money market funds. The recorded values of the Company’s accounts receivable, accounts payable and accrued and other current liabilities approximate their current fair values due to the relatively short-term nature of these accounts. The Company believes that the fair value of the capital leases, term debt and revolving credit facilities approximates its recorded amount as of December 31, 2014 as the interest rates on the term debt and revolving credit facilities are variable and the rates for each are based on market interest rates after consideration of default and credit risk (using level 2 inputs).
Cash and Cash Equivalents & Restricted Cash	Cash and Cash Equivalents—Cash consists of cash maintained in checking and savings accounts. All highly liquid investments purchased with an original maturity date of 90 days or less at the date of purchase are considered to be cash equivalents. Cash equivalents consist of money market funds.
	Restricted Cash—Restricted cash as of December 31, 2014 consists of cash required to be deposited with financial institutions for security deposits for some of the Company's office lease agreements.
Concentration of Credit Risk	Concentration of Credit Risk—Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and accounts receivable. A significant portion of the Company’s cash is held at three major financial institutions that the Company's management has assessed to be of high credit quality. The Company has not experienced any losses in such accounts.
	The Company mitigates its credit risk with respect to accounts receivable by performing credit evaluations and monitoring agencies' and advertisers' accounts receivable balances. As of December 31, 2014, two agency holding companies and no single advertiser accounted for 10% of more of accounts receivable. As of December 31, 2013, no single agency holding company or advertiser accounted for 10% or more of accounts receivable.
	With respect to revenue concentration, the Company defines a customer as an advertiser that is a distinct source of revenue and is legally bound to pay for the advertising services that the Company delivers on the advertiser’s behalf. The Company counts all advertisers within a single corporate structure as one customer even in cases where multiple brands, branches or divisions of an organization enter into separate contracts with the Company. During the years ended December 31, 2014, 2013 and 2012, no single customer represented 10% or more of revenue.
	The Company also monitors the percentage of revenue from advertising agencies, even though advertising agencies that act on behalf of the Company’s advertisers are not considered customers based on the definition above. If all branches and divisions within each global advertising agency were considered to be a single agency for this purpose, two agency holding companies would have been associated with 10% or more of revenue during the years ended December 31, 2014 and 2013 and three agency holding companies would have been associated with 10% or more of revenue during the year ended December 31, 2012.
Provision for Doubtful Accounts	Provision for Doubtful Accounts and Sales Reserves—The Company records a provision for doubtful accounts based on historical experience and a detailed assessment of the collectability of its accounts receivable. In estimating the allowance for doubtful accounts, management considers, among other factors, the aging of the accounts receivable, historical write-offs and the credit-worthiness of each customer. The Company also estimates sales returns and allowances in the same period the related revenue is recorded. These estimates are based on an analysis of credits issued for billing corrections. If circumstances change, such as higher-than-expected defaults or an unexpected material adverse change in a major customer’s ability to meet its financial obligations, the Company’s estimate of these provisions could change by a material amount.
Property and Equipment	Property and Equipment—Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization is computed using the straight-line method over the estimated useful lives of the related assets. Maintenance and repairs are charged to expense as incurred, and improvements and betterments are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation or amortization, as applicable, are removed from the balance sheet and any resulting gain or loss is reflected in operations in the period realized.
	Construction in progress primarily includes costs related to the leasehold improvements. Interest capitalized during the periods presented was not material.
	Leasehold improvements are amortized on a straight-line basis over the term of the lease, or the useful life of the assets, whichever is shorter. Depreciation and amortization periods for the Company’s property and equipment are as follows:
	Asset Classification	Estimated Useful Life
	Capitalized internal-use software costs	2–3 years
	Computer hardware and software	2–3 years
	Furniture and fixtures	5 years
Internal Use Software Development Costs	Internal-Use Software Development Costs—The Company incurs costs to develop software for internal use. The Company expenses all costs that relate to the planning and post implementation phases of development as research and development expense. The Company capitalizes costs when preliminary efforts are successfully completed, management has authorized and committed project funding, and it is probable that the project will be completed and will be used as intended. Costs incurred for enhancements that are expected to result in additional material functionality are capitalized. The Company capitalized $9.4 million, $6.3 million and $4.7 million for the years ended December 31, 2014, 2013 and 2012, respectively. These capitalized amounts are included in property, equipment and software—net on the consolidated balance sheets. Amortization commences when the website or software for internal use is ready for its intended use and the amortization period is the estimated useful life of the related asset.
Impairment of Long-lived Asset	Impairment of Long-lived Assets—The Company periodically reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset is impaired or the estimated useful life is no longer appropriate. If indicators of impairment exist and the undiscounted projected cash flows associated with an asset are less than the carrying amount of the asset, an impairment loss is recorded to write the asset down to its estimated fair value. Fair value is estimated based on discounted future cash flows. No impairment charges were recorded during the years ended December 31, 2014, 2013 and 2012.
Business Combinations	Business Combinations—The Company accounts for business combinations using the acquisition accounting method as required under the provisions of FASB ASC 805, Business Combinations, or ASC 805. The total purchase price is allocated to the assets acquired and liabilities assumed based on fair values at the date of acquisition. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the identifiable assets acquired and the liabilities assumed.
	Best estimates and assumptions are used in the purchase price allocation process to accurately value assets acquired and liabilities assumed at the business combination date. These estimates and assumptions are inherently uncertain and subject to refinement. As a result, during the preliminary purchase price allocation period, which may be up to one year from the business combination date, the Company may record adjustments to the assets acquired and liabilities assumed, with the corresponding adjustment to goodwill. After the preliminary purchase price allocation period, adjustments are recorded in the operating results in the period in which the adjustments were determined.
	The fair value assigned to identifiable intangible assets acquired is determined using the income approach which discounts expected future cash flows to present value using estimations and assumptions determined by management. The identifiable intangible assets are subject to amortization on a straight-line basis as this best approximates the benefit period related to these assets.
	The excess of the purchase price over the identified tangible and intangible assets, less liabilities assumed, is recorded as goodwill and primarily reflects the value of the synergies expected to be generated from combining the Company's and the acquired entity’s technology and operations. Generally, the goodwill is not deductible for income tax purposes.
Goodwill
	Goodwill, Intangibles and Impairment Assessments —Goodwill represents the excess of the aggregate purchase price paid over the fair value of the net tangible and intangible assets acquired. Intangible assets that are not considered to have an indefinite useful life are amortized over their useful lives. The Company evaluates the estimated remaining useful lives of purchased intangible assets and whether events or changes in circumstances warrant a revision to the remaining periods of amortization.
	Goodwill is not amortized and is tested for impairment at least annually or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. The Company has determined that it operates as one reporting unit and has selected December 1 as the date to perform its annual impairment test.
	In the impairment assessment of its goodwill, the Company performs a two step impairment test, which involves assumptions regarding estimated future cash flows to be derived from the Company. If these estimates or their related assumptions change in the future, the Company may be required to record impairment for these assets. The first step of the impairment test involves comparing the fair value of the reporting unit to its net book value, including goodwill. If the net book value exceeds its fair value, then the Company would perform the second step of the goodwill impairment test to determine the amount of the impairment loss. The impairment loss would be calculated by comparing the implied fair value of the Company to its net book value. In calculating the implied fair value of the Company’s goodwill, the fair value of the Company would be allocated to all of the other assets and liabilities based on their fair values. The excess of the fair value of the Company over the amount assigned to its other assets and liabilities is the implied fair value of goodwill. An impairment loss would be recognized when the carrying amount of goodwill exceeds its implied fair value. There has been no impairment of goodwill during the year ended December 31, 2014, as the Company's reporting unit's fair value was substantially in excess of the carrying value based on the annual goodwill impairment test.
Revenue Recognition	Revenue Recognition—The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred or a service has been provided, customer fees are fixed or determinable, and collection is reasonably assured.
	Demand Side Platform—To date, the Company has generated most of its revenue by delivering digital advertisements to Internet users through various channels, including display, mobile, social and video. This aspect of its business is referred to as a demand side platform, or “DSP.” These arrangements are typically with advertising agencies on behalf of their advertiser clients and are generally evidenced by a fully-executed insertion order (“IO”) and are generally cancellable by the customer as to any unfulfilled portion without penalty. Generally, IOs describe the campaign objectives, state the number and type of advertising impressions to be delivered, the agreed upon rate for each delivered impression, and a fixed period of time for delivery.
	Customers are typically billed on a monthly basis for each campaign for impressions delivered during the prior month. The Company determines collectability by performing ongoing credit evaluations and monitoring its customers’ accounts receivable balances. For new customers and their agents, which may be advertising agencies or other third parties, the Company performs a credit check with an independent credit agency and may check credit references to determine creditworthiness. The Company only recognizes revenue when collection is reasonably assured.
	The determination of whether revenue from DSP arrangements should be reported on a gross or net basis is based on an assessment of whether the Company is acting as the principal or an agent in the transaction. In determining whether the Company acts as the principal or an agent, the Company follows the accounting guidance for principal-agent considerations. While none of the factors identified in this guidance is individually considered presumptive or determinative, the Company has concluded that it acts as a principal with respect to these arrangements because (a) the Company is the primary obligor and is responsible for (i) fulfilling the advertisement delivery, (ii) establishing the selling prices for delivery of the advertisements, (iii) selecting the media to fulfill the insertion order, and (iv) performing all billing and collection activities including retaining credit risk, and (b) the Company has the risk of fluctuating costs from its media vendors relative to fixed pricing negotiated with its customers and has discretion in selecting media vendors when fulfilling a customer’s campaign. Based on this conclusion, the Company reports revenue earned and costs incurred with respect to its full-service DSP on a gross basis.
	In addition to delivering internet advertising through its full-service DSP, the Company licenses a self-service version of its DSP Based on the accounting guidance for principal-agent considerations, the Company has concluded that it acts as an agent with respect to these arrangements because (i) the Company is not the primary obligor, (ii) the Company does not have inventory risk as the customer chooses the inventory to purchase on a real-time basis, (iii) the media spend of the campaign is determined by the customer through the real-time bidding process, and (iv) the amount earned by the Company is based on a percentage of the media spend of the customer’s campaign. Based on this conclusion, the Company reports revenue earned and costs incurred with respect to its self-service DSP on a net basis.
	On occasion, the Company has offered customer incentive programs that provide rebates after achieving a specified level of advertising spending. The Company records reductions to revenue for estimated commitments related to these customer incentive programs. For transactions involving incentives, the Company recognizes revenue net of the estimated amount to be paid by rebate, provided that the rebate amount can be reasonably and reliably estimated and the other conditions for revenue recognition have been met. The Company’s policy requires that, if rebates cannot be reliably estimated, revenue is not recognized until reliable estimates can be made or the rebate program lapses.
	Data Management Platform—The Company licenses the right to access its data management platform ("DMP") to agencies and advertisers for their own use since its acquisition of [x+1]. These arrangements typically run over a period of one year or more and do not provide the customer with the right or ability to take possession of the platform. Revenue from license agreements is recognized ratably over the license term and was not material in the twelve months ended December 31, 2014.
	The Company also provides professional services such as implementation, support and training for its platform. Revenue is deferred until the services are completed and then recognized ratably over the term of the agreement.
	Multiple-Element Arrangements—The Company enters into arrangements to sell advertising that includes different media placements or ad services that are delivered at the same time during the campaign period, or within close proximity of one another. The Company allocates arrangement consideration in multiple-deliverable revenue arrangements at the inception of an arrangement to all deliverables or those packages in which all components of the package are delivered at the same time, based on the relative selling price method in accordance with the selling price hierarchy, which includes: (1) vendor-specific objective evidence (“VSOE”), if available; (2) third-party evidence (“TPE”), if VSOE is not available; and (3) best estimate of selling price (“BESP”), if neither VSOE nor TPE is available. To date, the Company has not been able to establish VSOE or selling price based on TPE for any of its advertising offerings.    When it is unable to establish selling price using VSOE or TPE, the Company uses BESP in its allocation of arrangement consideration. The objective of BESP is to determine the price at which the Company would transact a sale if the service were sold on a stand-alone basis. BESP is generally used to allocate the selling price to deliverables in the Company’s multiple element arrangements. The Company determines BESP for deliverables by considering multiple factors, including, but not limited to, prices it charges for similar offerings, market conditions, competitive landscape and pricing practices. In particular, the Company reviews multiple data points to determine BESP, including price lists used by the Company’s sales team in pricing negotiations, historical average and median pricing achieved in prior contractual customer arrangements and input from the Company’s sales operation department regarding what it believes the deliverables could be sold for on a stand-alone basis. BESP is determined at an advertising unit level that is consistent with the Company’s underlying market strategy and stratified based on specific consideration of channel, geography, industry and size, as deemed necessary. The Company regularly reviews BESP.
	With some customers, the Company enters into arrangements for both DMP and DSP services at the same time, or within close proximity of one another. In such circumstances, each element is accounted for as a separate unit of accounting because the following criteria are met: the delivered services have value to the customer on a standalone basis as the services are sold separately; the arrangement does not provide the right to return any of the delivered services and performance of the undelivered services is considered probable and is substantially controlled by the Company.
	The Company recognizes the relative fair value of advertising services as they are delivered, assuming all other revenue recognition criteria are met. The Company limits the amount of allocable arrangement consideration to amounts that are fixed or determinable and that are not contingent on future performance or future deliverables.
	Deferred revenue is comprised of contractual billings in excess of recognized revenue and payments received in advance of revenue recognition.
Multiple-Element Arrangements	Multiple-Element Arrangements—The Company enters into arrangements to sell advertising that includes different media placements or ad services that are delivered at the same time during the campaign period, or within close proximity of one another. The Company allocates arrangement consideration in multiple-deliverable revenue arrangements at the inception of an arrangement to all deliverables or those packages in which all components of the package are delivered at the same time, based on the relative selling price method in accordance with the selling price hierarchy, which includes: (1) vendor-specific objective evidence (“VSOE”), if available; (2) third-party evidence (“TPE”), if VSOE is not available; and (3) best estimate of selling price (“BESP”), if neither VSOE nor TPE is available. To date, the Company has not been able to establish VSOE or selling price based on TPE for any of its advertising offerings.    When it is unable to establish selling price using VSOE or TPE, the Company uses BESP in its allocation of arrangement consideration. The objective of BESP is to determine the price at which the Company would transact a sale if the service were sold on a stand-alone basis. BESP is generally used to allocate the selling price to deliverables in the Company’s multiple element arrangements. The Company determines BESP for deliverables by considering multiple factors, including, but not limited to, prices it charges for similar offerings, market conditions, competitive landscape and pricing practices. In particular, the Company reviews multiple data points to determine BESP, including price lists used by the Company’s sales team in pricing negotiations, historical average and median pricing achieved in prior contractual customer arrangements and input from the Company’s sales operation department regarding what it believes the deliverables could be sold for on a stand-alone basis. BESP is determined at an advertising unit level that is consistent with the Company’s underlying market strategy and stratified based on specific consideration of channel, geography, industry and size, as deemed necessary. The Company regularly reviews BESP.
	With some customers, the Company enters into arrangements for both DMP and DSP services at the same time, or within close proximity of one another. In such circumstances, each element is accounted for as a separate unit of accounting because the following criteria are met: the delivered services have value to the customer on a standalone basis as the services are sold separately; the arrangement does not provide the right to return any of the delivered services and performance of the undelivered services is considered probable and is substantially controlled by the Company.
	The Company recognizes the relative fair value of advertising services as they are delivered, assuming all other revenue recognition criteria are met. The Company limits the amount of allocable arrangement consideration to amounts that are fixed or determinable and that are not contingent on future performance or future deliverables.
Cost of Revenue	costs—Media costs consists primarily of cost for advertising impressions purchased from real-time advertising exchanges and other third parties.
Research and Development	Research and Development—Research and development expenses include costs associated with the maintenance and ongoing development of the Company’s technology, including compensation and employee benefits and allocated costs associated with the Company’s engineering and research and development departments, as well as costs for contracted services and supplies. Allocated costs include charges for facilities, office expenses, telephones, and other miscellaneous expenses. The Company reviews costs incurred in the application development stage and assesses such costs for potential capitalization.
Sales and Marketing	Sales and Marketing—Sales and marketing expenses consist primarily of compensation (including commissions) and employee benefits of sales and marketing personnel and related support teams, allocated costs, amortization of acquired intangible assets, certain advertising costs, travel, trade shows and marketing materials. Allocated costs include charges for facilities, office expenses, telephones, and other miscellaneous expenses. The Company incurred advertising costs of $6.0 million, $3.6 million and $0.1 million for the years ended December 31, 2014, 2013 and 2012, respectively.
General and Administrative	General and Administrative—General and administrative expenses include facilities costs, executive and administrative compensation and employee benefits, depreciation, professional services fees, insurance costs, bad debt and other allocated costs, such as facility-related expenses, supplies and other fixed costs. Allocated costs include charges for facilities, office expenses, telephones, and other miscellaneous expenses.
Stock-Based Compensation	Stock-based Compensation—The Company measures compensation expense for all stock-based payment awards, including stock options granted to employees, based on the estimated fair value of the awards on the date of the grant. The fair value of each stock option granted is estimated using the Black-Scholes option pricing model. Stock-based compensation is recognized on a straight-line basis over the requisite vesting period, net of estimated forfeitures. The forfeiture rate is based on an analysis of the Company’s actual historical forfeitures.
	The Company accounts for stock options issued to non-employees based on the fair value of the awards determined using the Black-Scholes option pricing model.
Preferred Stock Warrant Liability	Preferred Stock Warrant Liability—Free standing warrants related to shares that are redeemable or contingently redeemable were classified as a liability on the Company’s consolidated balance sheet. The fully-vested convertible preferred stock warrants were subject to re-measurement at each balance sheet date, and any change in fair value is recognized as a component of other expense, net. As completion of the Company’s initial public offering constituted a liquidation event, the convertible preferred stock warrants were converted into common stock or warrants to purchase common stock, and the liability was reclassified to additional paid-in capital in the third quarter of 2013.
Income Taxes	Income Taxes—The Company accounts for income taxes using an asset and liability approach. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Operating loss and tax credit carry-forwards are measured by applying currently enacted tax laws. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized.
	The Company recognizes the tax effects of an uncertain tax position only if it is more likely than not to be sustained based solely on its technical merits as of the reporting date, and then, only in an amount more likely than not to be sustained upon review by the tax authorities. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.
Recently Issued and Adopted Accounting Pronouncements	Recently Issued and Adopted Accounting Pronouncements—Under the Jumpstart Our Business Startups Act (the "JOBS Act"), we qualify as an “emerging growth company.” We have irrevocably elected to opt out of the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act, and, therefore, we will be subject to the same new or revised accounting standards as other public companies that are not “emerging growth companies.”
	In May 2014, the FASB issued new accounting guidance related to revenue recognition. This new standard will replace all current U.S. GAAP guidance on this topic and eliminate all industry-specific guidance. The new revenue recognition standard provides a unified model to determine when and how revenue is recognized. The core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration for which the entity expects to be entitled in exchange for those goods or services. This guidance will be effective beginning January 1, 2017 and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. We have not yet determined if we will apply this new accounting standard retrospectively or as a cumulative-effect adjustment and are in the process of evaluating the impact of adopting this standard on our financial statements.
	In August 2014, the FASB issued new guidance related to management responsibility to assess and provide related disclosure of the Company’s ability to continue as a going concern. This ASU will be effective for annual periods ending after December 15, 2016. The adoption of this guidance will not have a material impact on the Company's consolidated financial statements.

NATURE_OF_BUSINESS_AND_SUMMARY2

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of changes in the allowance for doubtful accounts	The following is a summary of activities in allowance for doubtful accounts and sales reserves for the fiscal years indicated (in thousands):
	Years ended December 31,		Allowances Beginning Balance		Charged Against Revenue		Charged to Expense		Write-offs, Adjustments, Net of Recovery			Allowances Ending Balance
	2014		$	1,752	$	796	$	523	$	(860	)	$	2,211
	2013		1,003		160		569		20			1,752
	2012		442		365		285		(89		)	1,003
Schedule of depreciation and amortization periods for the Company's property and equipment	Depreciation and amortization periods for the Company’s property and equipment are as follows:
	Asset Classification	Estimated Useful Life
	Capitalized internal-use software costs	2–3 years
	Computer hardware and software	2–3 years
	Furniture and fixtures	5 years

FAIR_VALUE_MEASUREMENTS_Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Schedule of Company's fair value hierarchy for its financial assets and financial liabilities that are carried at fair value	The following tables set forth the Company’s financial instruments that were measured at fair value on a recurring basis as of December 31, 2014 and 2013, by level within the fair value hierarchy (in thousands):
	31-Dec-14	Fair Value		Level 1		Level 2		Level 3
	Money market funds (included in cash and cash equivalents)	$	22,904	$	22,904	$	—	$	—
	31-Dec-13	Fair Value		Level 1		Level 2		Level 3
	Money market funds (included in cash and cash equivalents)	$	2,900	$	2,900	$	—	$	—

PROPERTY_EQUIPMENT_AND_SOFTWAR1

PROPERTY, EQUIPMENT AND SOFTWARE, NET (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Schedule of property, equipment and software	Property, equipment and software, net as of December 31, 2014 and 2013, consisted of the following (in thousands):
		December 31,
		2014			2013
	Capitalized internal-use software costs	$	23,385		$	14,030
	Computer hardware and software	46,299			17,077
	Furniture and fixtures	11,674			1,735
	Leasehold improvements	36,811			815
	Construction in progress	—			3,622
	Total	118,169			37,279
	Accumulated depreciation and amortization	(28,728		)	(11,485		)
	Total property, equipment and software, net	$	89,441		$	25,794

BUSINESS_COMBINATIONS_BUSINESS1

BUSINESS COMBINATIONS BUSINESS COMBINATIONS (Tables)	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Schedule of Consideration For Business Acquisitions
	Purchase consideration:
	Cash	$	98,045
	Fair value of 5,253,084 shares common stock transferred	82,421
	Total preliminary purchase price	$	180,466
Schedule of Purchase Price Allocation
		Goodwill
	Balance as of December 31, 2013	$	—
	Goodwill acquired	114,871
	Goodwill adjustments (1)	541
	Balance as of December 31, 2014	$	115,412
	Current assets	$	32,005
	Non-current assets	3,999
	Current liabilities	(28,893		)
	Non-current liabilities	(16,216		)
	Net acquired tangible assets	(9,105		)
	Identifiable intangible assets	74,700
	Goodwill	114,871
	Total preliminary purchase price	$	180,466
Schedule of Finite-Lived Intangible Assets
								As of December 31, 2014
		Estimated Useful Life (in years)		Preliminary Fair Value				Accumulated Amortization			Net Book Value
				(in thousands)
	Developed technology	4-Mar		$	42,100			$	(3,703	)	$	38,397
	Customer relationships	8-Jul		27,700				(1,107		)	26,593
	Trademarks	5		2,000				(128		)	1,872
	Non-compete agreements	2		2,900				(463		)	2,437
	Total			$	74,700			(5,401		)	69,299
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense
	Year ending December 31,		Amortization
	2015		$	16,908
	2016		16,445
	2017		14,095
	2018		8,851
	2019		3,738
	Thereafter		9,262
	Total		$	69,299
Pro Forma Information	(in thousands):
		Years ended December 31,
		2014				2013
	Pro forma revenue	$	468,881			$	310,469
	Pro forma net loss	$	(78,312	)		$	(50,666	)

ACCRUED_AND_OTHER_CURRENT_LIAB1

ACCRUED AND OTHER CURRENT LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
Schedule of accrued and other current liabilities	Accrued and other current liabilities as of December 31, 2014 and 2013 consisted of the following (in thousands):
		December 31,
		2014		2013
	Payroll and benefit related expenses	$	16,379	$	15,476
	Other accrued expenses	16,879		6,108
	Total accrued and other current liabilities	$	33,258	$	21,584

CAPITAL_LEASES_Tables

CAPITAL LEASES (Tables)	12 Months Ended
	Dec. 31, 2014
Leases [Abstract]
Schedule of approximate remaining future minimum lease payments under non-cancelable capital leases	The remaining future minimum lease payments under these non-cancelable capital leases as of December 31, 2014 were as follows (in thousands):
	Year ending December 31,	Future Payments
	2015	$	6,354
	2016	6,412
	2017	4,726
	2018	2,016
	2019	57
	Thereafter	—
	Total minimum lease payments	$	19,565
	Less: amount representing interest and taxes	(1,742		)
	Less: current portion of minimum lease payments	(5,482		)
	Capital lease obligations, net of current portion	$	12,341

OTHER_INCOME_EXPENSENET_Tables

OTHER INCOME (EXPENSE)—NET (Tables)	12 Months Ended
	Dec. 31, 2014
Other Income and Expenses [Abstract]
Schedule of other income (expense), net	Other income (expense)—net for the years ended December 31, 2014, 2013 and 2012, consisted of the following (in thousands):
		Years ended December 31,
		2014			2013			2012
	Gain (loss) on foreign currency transactions	$	(5,259	)	$	(205	)	$	43
	Other non-operating income (loss), net	(8		)	(103		)	92
	Total other income (expense)—net	$	(5,267	)	$	(308	)	$	135

DEBT_Tables

DEBT (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of future principal payments of long-term debt	Future principal payments of long-term debt as of December 31, 2014 were as follows (in thousands):
	Year ending December 31,	Future Payments
	2015	$	6,000
	2016	6,000
	2017	6,000
	2018	6,000
	2019	6,000
	Total	30,000
	Less: current portion of long-term debt	(6,000		)
	Long-term debt, net of current portion	$	24,000

STOCKHOLDERS_EQUITY_Tables

STOCKHOLDERS' EQUITY (Tables)	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Schedule of shares of common stock reserved for issuance	The Company’s shares of capital stock reserved for issuance under the Company's equity incentive plans as of December 31, 2014 were as follows:
		31-Dec-14
	Options outstanding	6,290,519
	Restricted stock awards and units outstanding	2,507,523
	Available for future stock option and restricted stock unit grants	3,688,676
	Available for future employee stock purchase plan purchases	1,286,532
	Total shares reserved	13,773,250
Summary of option award activity	The following tables summarize option award activity:
		Number of		Weighted-				Weighted-	Aggregate
		Options		Average				Average	Intrinsic Value
		Outstanding		Exercise				Remaining	(in thousands)
				Price				Contractual
								Life
								(Years)
	Balance at December 31, 2013	7,410,588		$	6.97			8.5	$	404,106
	Options granted (weighted average fair value of $17.73 per share)	892,908		32.43
	Options exercised	-1,499,190		2.53
	Options forfeited	-513,787		12.59
	Balance at December 31, 2014	6,290,519		$	11.18			7.8	$	46,926
	Options vested and expected to vest—December 31, 2014	5,975,101		$	10.82			7.8	$	45,768
	Options vested and exercisable—December 31, 2014	3,249,674		$	6.59			7.3	$	31,934
Schedule of assumptions used to value stock-based awards granted to employees	The assumptions used to value options granted to employees were as follows:
		Years ended December 31,
		2014		2013		2012
	Expected term (years)	5.5–6.3		5.3–6.6		5.3–7.3
	Volatility	55.6%–59.5%		53.8%–64.9%		61.2%–63.4%
	Risk-free interest rate	1.84%–1.97%		1.04%–1.88%		0.70%–1.21%
	Dividend yield	—		—		—
Summary of RSU activity	Restricted Stock Units ("RSUs") and Restricted Stock Awards ("RSAs")—A summary of RSU and RSA activity for the year ended December 31, 2014 is as follows:
		Number of Shares			Weighted Average Grant Date Fair Value
	Unvested at December 31, 2013	382,402			$	55.86
	Granted	2,382,180			20.4
	Vested and issued	(110,359	)		51.29
	Canceled	(138,912	)		42.7
	Unvested at December 31, 2014	2,515,311			$	23.2
Schedule of assumptions used to calculate stock-based compensation for each stock purchase right granted under the ESPP	The assumptions used to calculate our stock-based compensation for each stock purchase right granted under the ESPP were as follows:
		Years ended December 31,
		2014		2013
	Expected term (years)	0.5–0.7		0.7
	Volatility	66.2%–77.4%		66.20%
	Risk-free interest rate	0.06%–0.08%		0.07%
	Dividend yield	—		—
	The assumptions used to calculate our stock-based compensation for each stock purchase right granted under the ESPP were as follows:
		Years ended December 31,
		2014		2013
	Expected term (years)	0.5–0.7		0.7
	Volatility	66.2%–77.4%		66.20%
	Risk-free interest rate	0.06%–0.08%		0.07%
	Dividend yield	—		—
	Equity compensation allocation
	The following table summarizes the allocation of stock-based compensation in the accompanying consolidated statements of operations (in thousands):
		Years ended December 31,
		2014				2013			2012
	Other cost of revenue	$	1,758			$	471		$	37
	Research and development	5,039				2,308			734
	Sales and marketing	10,372				4,482			1,100
	General and administrative	6,361				3,581			1,450
	Total	$	23,530			$	10,842		$	3,321

NET_INCOME_LOSS_PER_SHARE_Tabl

NET INCOME (LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of computation of net loss per common share	The following table sets forth the computation of net loss per share of common stock (in thousands, except per share amounts):
		Years ended December 31,
		2014				2013			2012
	Net loss	$	(64,311	)		$	(20,932	)	$	(10,343	)
	Weighted-average shares used to compute basic and diluted net loss per share	37,001				15,177			8,024
	Basic and diluted net loss per share	$	(1.74	)		$	(1.38	)	$	(1.29	)
Schedule of anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders	The following securities were excluded from the calculation of diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented (in thousands):
		Years ended December 31,
		2014			2013			2012
	Convertible preferred stock	—			—			19,479
	Employee stock options	6,291			7,409			5,830
	Shares subject to repurchase	99			316			—
	Restricted stock units (RSUs) and restricted stock awards (RSAs)	2,508			383			—
	Employee stock purchase plan	58			58			—
	Convertible preferred stock warrants	—			—			267
		8,956			8,166			25,576

INCOME_TAXES_INCOME_TAXES_Tabl

INCOME TAXES INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Summary of Income Tax Contingencies [Table Text Block]	The table below provides a reconciliation of the beginning and ending amount of unrecognized tax benefits (excluding interest and penalties), related to uncertain tax positions, for the years ended December 31, 2014, 2013 and 2012 (in thousands):
		Years ended December 31,
		2014			2013			2012
	Unrecognized benefit—beginning of period	$	669		$	272		$	184
	Gross increases—prior year tax positions	46			126			10
	Gross increases—current year tax positions	2,749			271			78
	Unrecognized benefit—end of period	$	3,464		$	669		$	272
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]	he following table presents domestic and foreign components of income (loss) before income taxes for the periods presented (in thousands):
		Years ended December 31,
		2014			2013			2012
	Domestic	$	(70,438	)	$	(21,568	)	$	(10,637	)
	International	1,888			921			378
	Total	$	(68,550	)	$	(20,647	)	$	(10,259	)
Schedule of Components of Income Tax Expense (Benefit)	The components of the income tax (benefit) for income taxes were as follows (in thousands):
		Years ended December 31,
		2014			2013			2012
	Current:
	Federal	$	—		$	—		$	—
	State	9			(4		)	11
	Foreign	1,159			289			73
	Deferred:
	Federal	(4,042		)	—			—
	State	(713		)	—			—
	Foreign	(652		)	—			—
	Total benefit (provision) for income taxes	$	(4,239	)	$	285		$	84
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
		December 31,
		2014			2013
	Deferred tax assets:
	Tax credit carry-forwards	$	6,877		$	2,256
	Net operating loss carry-forwards	45,281			13,118
	Charitable contributions	323			133
	Accrued liabilities and allowances	18,171			5,421
		70,652			20,928
	Deferred tax liability:
	Depreciation and amortization	(32,194		)	(5,166		)
		(32,194		)	(5,166		)
	Net deferred tax assets before valuation allowance	$	38,458		$	15,762
	Valuation allowance	(38,159		)	(15,762		)
	Net deferred tax assets (liabilities)	$	299		$	—

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum lease payments under non-cancelable operating leases	Approximate remaining future minimum cash lease payments under these non-cancelable operating leases as of December 31, 2014 were as follows (in thousands):
	Year ending December 31,	Future Payments
	2015	$	18,283
	2016	20,318
	2017	19,877
	2018	18,592
	2019	21,024
	Thereafter	44,882
		$	142,976

SEGMENTS_Tables

SEGMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Schedule of total revenue generated through sales personnel located in the respective locations	The following table summarizes total revenue generated through sales personnel located in the respective locations (in thousands):
		Years ended December 31,
		2014		2013		2012
	North America	$	349,289	$	213,601	$	96,289
	All Other Countries	59,352		27,004		10,300
	Total revenue	$	408,641	$	240,605	$	106,589
Schedule of total long-lived assets in the respective locations	The following table summarizes total long-lived assets in the respective locations (in thousands):
		December 31,
		2014		2013
	North America	$	85,355	$	23,956
	All Other Countries	4,086		1,838
	Total long-lived assets	$	89,441	$	25,794

NATURE_OF_BUSINESS_AND_SUMMARY3

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)	1 Months Ended	12 Months Ended			1 Months Ended
	Feb. 28, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2013	Feb. 18, 2014
Initial public offering
Number of shares of common stock sold by the entity	2,000,000		4,000,000
Number of shares of common stock sold by selling stockholders	3,000,000
Issuance Price Per Share (in dollars per share)						$61
Total gross proceeds from the offering	$122,000,000
Aggregate net proceeds received from offering	115,400,000	115,403,000	103,612,000	0
Initial Public Offering
Initial public offering
Sale of Stock, Number of Shares Issued in Transaction					4,000,000
Number of shares of common stock sold by selling stockholders					600,000
Issuance Price Per Share (in dollars per share)					$29
Total gross proceeds from the offering					116,000,000
Aggregate net proceeds received from offering					$103,300,000

NATURE_OF_BUSINESS_AND_SUMMARY4

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Concentration of credit risk
Impairment of long-lived assets	$0	$0	$0
Cash | Credit concentration
Concentration of credit risk
Number of financial institutions where a significant portion of cash is held	3
Accounts receivable | Customer concentration
Concentration of credit risk
Number of customers	0	0
Revenue | Customer concentration
Concentration of credit risk
Number of customers	2	2	3

NATURE_OF_BUSINESS_AND_SUMMARY5

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Internal Use Software Development Costs
Internal-use software costs capitalized	$9,400,000	$6,300,000	$4,700,000
Amortization expense	5,200,000	3,400,000	2,300,000
Impairment of Long-lived Assets
Impairment of long-lived assets	0	0	0
Sales and Marketing
Advertising costs	$6,000,000	$3,600,000	$100,000
Computer hardware and purchased software | Minimum
Property and equipment
Estimated useful life	2 years
Computer hardware and purchased software | Maximum
Property and equipment
Estimated useful life	3 years
Capitalized internal-use software costs | Minimum
Property and equipment
Estimated useful life	2 years
Capitalized internal-use software costs | Maximum
Property and equipment
Estimated useful life	3 years
Office equipment, furniture and fixtures
Property and equipment
Estimated useful life	5 years

FAIR_VALUE_MEASUREMENTS_Detail

FAIR VALUE MEASUREMENTS (Details) (Recurring, Money market funds (included in cash and cash equivalents), USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$22,904	$2,900
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	22,904	2,900
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$0	$0

PROPERTY_EQUIPMENT_AND_SOFTWAR2

PROPERTY, EQUIPMENT AND SOFTWARE, NET (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, equipment and software
Total	$118,169,000	$37,279,000
Accumulated depreciation and amortization	-28,728,000	-11,485,000
Total property, equipment and software, net	89,441,000	25,794,000
Depreciation and amortization expense, excluding amortization of internal use software costs	13,100,000	4,500,000	1,300,000
Amortization expense	5,200,000	3,400,000	2,300,000
Capital leases	19,200,000	600,000
Capitalized internal-use software costs
Property, equipment and software
Total	23,385,000	14,030,000
Computer hardware and software
Property, equipment and software
Total	46,299,000	17,077,000
Furniture and fixtures
Property, equipment and software
Total	11,674,000	1,735,000
Leasehold improvements
Property, equipment and software
Total	36,811,000	815,000
Construction in progress
Property, equipment and software
Total	$0	$3,622,000

BUSINESS_COMBINATIONS_Narrativ

BUSINESS COMBINATIONS - Narrative (Details) (USD $)	9 Months Ended	12 Months Ended			0 Months Ended	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 05, 2014	Sep. 30, 2013
Business Acquisition [Line Items]
Cash payment	$98,000,000
Shares issued	5,253,084
Goodwill		115,412,000	0
Tax benefit		-4,239,000	285,000	84,000
x Plus 1
Business Acquisition [Line Items]
Cash payment					98,045,000
Shares issued					5,253,084
Fair value of 5,253,084 shares common stock transferred					82,421,000
Total preliminary purchase price					180,466,000
Goodwill					114,871,000
Amortization of intangible assets		5,400,000
Tax benefit						-4,100,000
x Plus 1 | General and administrative
Business Acquisition [Line Items]
Acquisition costs					$4,900,000

BUSINESS_COMBINATIONS_Schedule

BUSINESS COMBINATIONS - Schedule of Purchase Price Allocation (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Sep. 05, 2014
In Thousands, unless otherwise specified
Business Acquisition [Line Items]
Goodwill	$115,412	$0
x Plus 1
Business Acquisition [Line Items]
Current assets			32,005
Non-current assets			3,999
Current liabilities			-28,893
Non-current liabilities			-16,216
Net acquired tangible assets			-9,105
Identifiable intangible assets			74,700
Goodwill			114,871
Total preliminary purchase price			$180,466

BUSINESS_COMBINATIONS_Intangib

BUSINESS COMBINATIONS - Intangible Assets Acquired (Details) (x Plus 1, USD $)	0 Months Ended	12 Months Ended
	Sep. 05, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Amortization of Intangible Assets		$5,400,000
Preliminary Fair Value	74,700,000
Accumulated Amortization		-5,401,000
Net Book Value		69,299,000
Developed technology
Business Acquisition [Line Items]
Preliminary Fair Value	42,100,000
Accumulated Amortization		-3,703,000
Net Book Value		38,397,000
Customer relationships
Business Acquisition [Line Items]
Preliminary Fair Value	27,700,000
Accumulated Amortization		-1,107,000
Net Book Value		26,593,000
Trademarks
Business Acquisition [Line Items]
Estimated Useful Life (in years)	5 years
Preliminary Fair Value	2,000,000
Accumulated Amortization		-128,000
Net Book Value		1,872,000
Non-compete agreements
Business Acquisition [Line Items]
Estimated Useful Life (in years)	2 years
Preliminary Fair Value	2,900,000
Accumulated Amortization		-463,000
Net Book Value		$2,437,000
Minimum | Developed technology
Business Acquisition [Line Items]
Estimated Useful Life (in years)	3 years
Minimum | Customer relationships
Business Acquisition [Line Items]
Estimated Useful Life (in years)	7 years
Maximum | Developed technology
Business Acquisition [Line Items]
Estimated Useful Life (in years)	4 years
Maximum | Customer relationships
Business Acquisition [Line Items]
Estimated Useful Life (in years)	8 years

BUSINESS_COMBINATIONS_Schedule1

BUSINESS COMBINATIONS - Schedule of Amortization Expense (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Business Combinations [Abstract]
2015	$16,908
2015	16,445
2016	14,095
2017	8,851
2018	3,738
Thereafter	9,262
Total	$69,299

BUSINESS_COMBINATIONS_Pro_Form

BUSINESS COMBINATIONS - Pro Forma (Details) (USD $)	12 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2013
Business Acquisition [Line Items]
Income Tax Expense (Benefit)	($4,239)	$285	$84
x Plus 1
Business Acquisition [Line Items]
Income Tax Expense (Benefit)				-4,100
Pro forma revenue	468,881	310,469
Pro forma net loss	($78,312)	($50,666)

ACCRUED_AND_OTHER_CURRENT_LIAB2

ACCRUED AND OTHER CURRENT LIABILITIES (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]
Payroll and benefit related expenses	$16,379	$15,476
Other accrued expenses	16,879	6,108
Total accrued and other current liabilities	$33,258	$21,584

CAPITAL_LEASES_Details

CAPITAL LEASES (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Leases [Abstract]
Property and equipment acquired under capital lease agreements	$19,200,000	$600,000
Approximate remaining future minimum lease payments under non-cancelable capital leases
2015	6,354,000
2015	6,412,000
2016	4,726,000
2017	2,016,000
Capital Leases, Future Minimum Payments Due in Five Years	57,000
Thereafter	0
Total minimum lease payments	19,565,000
Less: amount representing interest and taxes	-1,742,000
Less: current portion of minimum lease payments	-5,482,000	-203,000
Capital lease obligations, net of current portion	$12,341,000	$412,000

OTHER_INCOME_EXPENSENET_Detail

OTHER INCOME (EXPENSE)—NET (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Income and Expenses [Abstract]
Gain (loss) on foreign translation	($5,259)	($205)	$43
Other non-operating income (loss), net	-8	-103	92
Total other income (expense)-net	($5,267)	($308)	$135

DEBT_Details

DEBT (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Debt
Amount outstanding	$40,000,000
Applicable margin over variable rate basis (as a percent)	2.00%
Liquidity ratio		1.1
Future principal payments of long-term debt
2015	6,000,000
2017	6,000,000
2018	6,000,000
2019	6,000,000
Total	30,000,000
Long-term debt, net of current portion	23,335,000		19,568,000
Unamortized discounts	1,000,000
Repayments of assumed debt	11,100,000
2016	6,000,000
Federal funds rate
Debt
Applicable margin over variable rate basis (as a percent)	1.00%
Daily adjusting LIBOR rate
Debt
Applicable margin over variable rate basis (as a percent)	1.00%
Revolving line of credit, as amended in June 2013
Debt
Maximum amount available for borrowing	80,000,000
Amount outstanding	40,000,000
Maximum amount available for borrowing expressed as a percentage of certain eligible accounts	85.00%
Revolving line of credit | Base rate
Debt
Applicable margin over variable rate basis (as a percent)	2.13%
Revolving line of credit | Minimum | Base rate
Debt
Applicable margin over variable rate basis (as a percent)	1.63%
Revolving line of credit | Minimum | LIBOR
Debt
Applicable margin over variable rate basis (as a percent)	2.63%
Revolving line of credit | Maximum | LIBOR
Debt
Applicable margin over variable rate basis (as a percent)	3.13%
Letter of credit subfacility
Debt
Maximum amount available for borrowing	12,000,000
Debt Instrument, Aggregate Minimum Cash on Deposit	40,000,000
Amount outstanding	6,000,000
Debt Instrument, Periodic Payment, Principal	1,500,000
Debt Instrument, Required Cash on Deposit	30,000,000
Swing line subfacility
Debt
Maximum amount available for borrowing	2,500,000
Term loans
Future principal payments of long-term debt
Less: current portion of long-term debt	-6,000,000
Long-term debt, net of current portion	24,000,000
Term loans | Minimum | Base rate
Debt
Applicable margin over variable rate basis (as a percent)	2.50%
Term loans | Minimum | LIBOR
Debt
Applicable margin over variable rate basis (as a percent)	3.50%
Term loans | Maximum | Base rate
Debt
Applicable margin over variable rate basis (as a percent)	3.00%
Term loans | Maximum | LIBOR
Debt
Applicable margin over variable rate basis (as a percent)	4.00%
Revolving line of credit amended in March 2012
Debt
Maximum amount available for borrowing	30,000,000
Amount outstanding	$30,000,000

STOCKHOLDERS_EQUITY_Details

STOCKHOLDERS' EQUITY (Details) (USD $)	1 Months Ended	9 Months Ended	12 Months Ended			0 Months Ended
	Feb. 28, 2014	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 01, 2015	Feb. 18, 2014
STOCKHOLDERS' EQUITY (DEFICIT)
Total intrinsic value of options exercised			$38,100,000	$11,900,000	$1,100,000
Number of shares of common stock sold by the entity	2,000,000			4,000,000
Number of shares of common stock sold by selling stockholders	3,000,000
Issuance Price Per Share (in dollars per share)							$61
Total gross proceeds from the offering	122,000,000
Aggregate net proceeds received from offering	115,400,000		115,403,000	103,612,000	0
Shares of capital stock reserved for issuance
Total shares reserved			13,773,250
Stock Issued During Period, Shares, Acquisitions		5,253,084
Payments to Acquire Businesses, Gross		98,000,000
2013 Equity Incentive Plan
STOCKHOLDERS' EQUITY (DEFICIT)
Additional shares authorized			1,641,299
Employee stock purchase plan
Shares of capital stock reserved for issuance
Total shares reserved			1,286,532
Options
Shares of capital stock reserved for issuance
Total shares reserved			6,290,519
Unamortized stock-based compensation expense related to unvested common stock options			$25,400,000	$21,700,000	$12,500,000
Restricted stock units (RSUs) and restricted stock awards (RSAs)
Shares of capital stock reserved for issuance
Total shares reserved			2,507,523
Stock option and restricted stock unit grants
Shares of capital stock reserved for issuance
Total shares reserved			3,688,676
Subsequent Event [Member] | 2013 Equity Incentive Plan
STOCKHOLDERS' EQUITY (DEFICIT)
Additional shares authorized						2,100,126

STOCKHOLDERS_EQUITY_Details_2

STOCKHOLDERS' EQUITY (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Number of Shares Outstanding
Balance at the beginning of the period (in shares)	7,410,588
Options granted (weighted average fair value of $17.73 per share)	892,908
Options exercised (in shares)	-1,499,190
Options forfeited (in shares)	-513,787
Balance at the end of the period (in shares)	6,290,519	7,410,588
Options vested and expected to vest (in shares)	5,975,101
Options vested and exercisable (in shares)	3,249,674
Weighted average fair value (in dollars per share)	$17.73
Weighted-Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$6.97
Options granted (weighted average fair value of $17.73 per share)	$32.43
Options exercised (in dollars per share)	$2.53
Options forfeited (in dollars per share)	$12.59
Balance at the end of the period (in dollars per share)	$11.18	$6.97
Options vested and expected to vest (in dollars per share)	$10.82
Options vested and exercisable (in dollars per share)	$6.59
Weighted-Average Remaining Contractual Life
Balance	7 years 10 months 2 days	8 years 6 months
Options vested and expected to vest	7 years 9 months 18 days
Options vested and exercisable	7 years 3 months 10 days
Aggregate Intrinsic Value
Balance	$404,106,000			$46,926,000
Options vested and expected to vest	45,768,000
Options vested and exercisable	31,934,000
Total intrinsic value of options exercised	$38,100,000	$11,900,000	$1,100,000
2008 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price as a percentage of the fair market value of the common stock	100.00%
Expiration period	10 years
Vesting period	4 years
Number of shares of unvested stock repurchased	25,625	5,834
2013 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price as a percentage of the fair market value of the common stock	100.00%
Expiration period	10 years
Common stock reserved for issuance	5,000,000
Number of shares added to current plan for award granted but not exercised in full, pursuant to the terminated equity incentive plan	7,900,000
Annual increase in number of shares available for issuance on first day of each fiscal year following latest fiscal year	4,000,000
Annual increase in number of shares available for issuance on first day of each fiscal year following latest fiscal year as a percentage of outstanding common stock, as on last day of the immediately preceding fiscal year	5.00%
Additional shares authorized	1,641,299
Options | 2008 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of unvested shares	98,787	315,579		98,787

STOCKHOLDERS_EQUITY_Details_3

STOCKHOLDERS' EQUITY (Details 3) (USD $)	12 Months Ended			9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014
Summary of options outstanding and vested
Expected dividends	$0
Assumptions used to value stock-based awards granted to employees
Volatility, lower end (as a percent)	55.60%	53.80%	61.20%
Volatility, higher end (as a percent)	59.50%	64.90%	63.40%
Risk-free interest rate, lower end (as a percent)	1.84%	1.04%	0.07%
Risk-free interest rate, higher end (as a percent)	1.97%	1.88%	1.21%
Minimum
Assumptions used to value stock-based awards granted to employees
Expected term	5 years 6 months	5 years 3 months 18 days	5 years 3 months 18 days
Maximum
Assumptions used to value stock-based awards granted to employees
Expected term	6 years 3 months 18 days	6 years 7 months 6 days	7 years 3 months 18 days
Employee stock purchase plan
Assumptions used to value stock-based awards granted to employees
Expected term		8 months 12 days
Volatility (as a percent)		66.20%
Risk-free interest rate (as a percent)		0.07%
Dividend yield (as a percent)				0.00%
Employee stock purchase plan | Minimum
Assumptions used to value stock-based awards granted to employees
Expected term	6 months
Volatility (as a percent)	66.20%
Risk-free interest rate (as a percent)	0.06%
Employee stock purchase plan | Maximum
Assumptions used to value stock-based awards granted to employees
Expected term	8 months 12 days
Volatility (as a percent)	77.40%
Risk-free interest rate (as a percent)	0.08%

STOCKHOLDERS_EQUITY_Details_4

STOCKHOLDERS' EQUITY (Details 4) (USD $)	12 Months Ended			9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	$23,530,000	$10,842,000	$3,321,000
Options
Allocation of stock-based compensation and restricted stock for employees and non-employees
Unamortized stock-based compensation expense related to unvested common stock options	25,400,000	21,700,000	12,500,000
Weighted-average period over which stock-based compensation expense will be recognized				2 years 3 months
Cost of revenue
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	1,758,000	471,000	37,000
Research and development
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	5,039,000	2,308,000	734,000
Sales and marketing
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	10,372,000	4,482,000	1,100,000
General and administrative
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	$6,361,000	$3,581,000	$1,450,000

STOCKHOLDERS_EQUITY_Details_5

STOCKHOLDERS' EQUITY (Details 5) (USD $)	12 Months Ended			9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	892,908
Stock-based compensation expense	$23,530,000	$10,842,000	$3,321,000
Options outstanding (in shares)	6,290,519	7,410,588
2008 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price expressed as a percentage of fair market value of common stock on the first or the last trading day of the offering period	100.00%
2013 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price expressed as a percentage of fair market value of common stock on the first or the last trading day of the offering period	100.00%
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of deduction from eligible compensation authorized by employee to purchase common stock at discount	15.00%
Purchase price expressed as a percentage of fair market value of common stock on the first or the last trading day of the offering period	85.00%
Total compensation costs related to rights to purchase common shares but not yet vested which will be recognized over the offering period	1,600,000
Assumptions used to calculate stock-based compensation for each stock purchase right granted under the Employee Stock Purchase Plan (ESPP)
Expected term		8 months 12 days
Volatility (as a percent)		66.20%
Risk-free interest rate (as a percent)		0.07%
Dividend yield (as a percent)				0.00%
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards issued (in shares)	2,382,180
Granted	$20.40
Number of awards released (in shares)	110,359
Number of awards cancelled (in shares)	138,912
Unrecognized compensation expense	$43,800,000

STOCKHOLDERS_EQUITY_Details_6

STOCKHOLDERS' EQUITY (Details 6) (Restricted stock units (RSUs) and restricted stock awards (RSAs), USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014
Restricted stock units (RSUs) and restricted stock awards (RSAs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$2.30
Number of Shares
Unvested, beginning balance	382,402
Granted	2,382,180
Vested and issued	-110,359
Canceled	-138,912
Unvested, ending balance	2,515,311
Weighted Average Grant Date Fair Value
Unvested, beginning balance	$55.86
Granted	$20.40
Vested and issued	$51.29
Canceled	$42.70
Unvested, ending balance	$23.20

NET_INCOME_LOSS_PER_SHARE_Deta

NET INCOME (LOSS) PER SHARE (Details) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Computation of net loss per common share
Net loss	($64,311)	($20,932)	($10,343)
Weighted-average shares used to compute basic and diluted net loss per share	37,001	15,177	8,024
Basic and diluted net loss per share (in dollars per share)	($1.74)	($1.38)	($1.29)
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders (in shares)	8,956	8,166	25,576
Convertible Preferred Stock [Member]
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders (in shares)	0	0	19,479
Employee stock options
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders (in shares)	6,291	7,409	5,830
Shares subject to repurchase
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders (in shares)	99	316	0
Restricted stock units (RSUs) and restricted stock awards (RSAs)
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders (in shares)	2,508	383	0
Employee stock purchase plan
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders (in shares)	58	58	0
Series A Preferred Stock Warrant [Member]
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders (in shares)	0	0	267

INCOME_TAXES_Details

INCOME TAXES (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014
Income Tax Examination [Line Items]
Domestic	($70,438,000)	($21,568,000)	($10,637,000)
Tax benefit at federal statutory rate	34.00%	34.00%	34.00%
Tax credit carry-forwards	6,877,000	2,256,000
Deferred Tax Assets, Gross	70,652,000	20,928,000
Valuation allowance	-38,159,000	-15,762,000
Depreciation and amortization	-32,194,000	-5,166,000
Gross deferred tax liability	32,194,000	5,166,000
Deferred Tax Assets (Liabilities) Before Valuation Allowance, Net	38,458,000	15,762,000
Deferred Tax Assets, Net of Valuation Allowance	299,000	0
Valuation Allowance, Deferred Tax Asset, Change in Amount	22,400,000	6,900,000
Income tax (benefit) provision	4,239,000	-285,000	-84,000
Foreign	-652,000	0	0
State	-713,000	0	0
Federal	-4,042,000	0	0
Foreign	1,159,000	289,000	73,000
State	9,000	-4,000	11,000
Federal	0	0	0
Operating Loss Carryforwards	45,281,000	13,118,000
Charitable contributions	323,000	133,000
Accrued liabilities and allowances	18,171,000	5,421,000
Undistributed Earnings of Foreign Subsidiaries	2,300,000
State income taxes, net of federal effect	6.17%	0.01%	-0.07%
Foreign rate differential	0.20%	0.12%	0.54%
Change in valuation allowance	-31.94%	-28.42%	-25.16%
Meals and entertainment	-1.44%	-2.07%	-1.98%
Warrant liability	0.00%	-7.81%	-7.65%
Research credits	2.86%	2.79%	0.00%
Effective Income Tax Rate Reconciliation, Transaction Costs	-2.24%	0.00%	0.00%
Other	-1.41%	0.00%	-0.50%
Total provision	6.20%	-1.38%	-0.82%
International	1,888,000	921,000	378,000
Total	-68,550,000	-20,647,000	-10,259,000
Deferred tax liabilities related to acquisition				4,000,000
Federal
Income Tax Examination [Line Items]
Operating Loss Carryforwards	55,300,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	7,600,000
Excess Deduction Not to be Recognized Until Stock Option Exercise Deduction Reduces Taxes Payable	15,200,000
State
Income Tax Examination [Line Items]
Operating Loss Carryforwards	5,200,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	2,700,000
Excess Deduction Not to be Recognized Until Stock Option Exercise Deduction Reduces Taxes Payable	$700,000

COMMITMENTS_AND_CONTINGENCIES_1

COMMITMENTS AND CONTINGENCIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leases
Rent expense	$14,700,000	$4,300,000	$1,600,000
Future minimum lease payments under non-cancelable operating leases
2014 (remaining 9 months)	18,283,000
2015	20,318,000
2016	19,877,000
2017	18,592,000
2018	21,024,000
Thereafter	44,882,000
Total future payments	142,976,000
Letters of Credit and Bank Guarantees
Irrevocable letters of credit outstanding	6,800,000	3,400,000
Bank guarantees for security deposits	$2,915,000	$0

SEGMENTS_Details

SEGMENTS (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	segment
	manager
	business_activity
Segment Reporting [Abstract]
Number of business activities	1
Number of segment managers held accountable for operations, operating results or plans for levels or components below the consolidated unit level	0
Number of reportable segments	1
Number of operating segments	1
Segments
Total revenue	$408,641	$240,605	$106,589
Total long-lived assets	89,441	25,794
Revenue | Customer concentration
Segments
Number of customers	0	2	0
Accounts receivable | Customer concentration
Segments
Number of customers	2	0
North America
Segments
Total revenue	349,289	213,601	96,289
Total long-lived assets	85,355	23,956
All Other Countries
Segments
Total revenue	59,352	27,004	10,300
Total long-lived assets	$4,086	$1,838

SUBSEQUENT_EVENTS_SUBSEQUENT_E

SUBSEQUENT EVENTS SUBSEQUENT EVENTS (Details) (Letter of credit subfacility, USD $)	12 Months Ended	0 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Mar. 13, 2015
Subsequent Event [Line Items]
Debt Instrument, Aggregate Minimum Cash on Deposit	$40
Subsequent Event [Member]
Subsequent Event [Line Items]
Debt Instrument, Aggregate Minimum Cash on Deposit		$40