Rocket Fuel 10-Q 8 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document and Entity Information
Entity Registrant Name	Rocket Fuel Inc.
Entity Central Index Key	1477200
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		42,185,121
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current Assets:
Cash and cash equivalents	$92,055	$107,056
Accounts receivable, net	112,689	135,400
Deferred tax assets	1,716	1,716
Prepaid expenses	4,029	3,698
Other current assets	6,915	12,531
Total current assets	217,404	260,401
Property, equipment and software, net	91,752	89,441
Restricted cash	2,188	2,915
Intangible assets	65,072	69,299
Goodwill	115,412	115,412
Other assets	1,364	1,797
Total assets	493,192	539,265
Current Liabilities:
Accounts payable	63,408	76,085
Accrued and other current liabilities	28,833	33,258
Deferred revenue	3,124	593
Current portion of capital leases	5,691	5,482
Current portion of debt	45,720	45,705
Total current liabilities	146,776	161,123
Long-term debt—Less current portion	21,907	23,335
Capital leases—Less current portion	11,156	12,341
Deferred rent—Less current portion	26,521	26,818
Deferred tax liabilities	2,044	2,068
Other liabilities	808	814
Total liabilities	209,212	226,499
Commitments and contingencies (Note 12)
Stockholders’ Equity
Common stock, $0.001 par value— 1,000,000,000 authorized as of March 31, 2015 and December 31, 2014; 42,141,742 and 42,002,533 issued and outstanding as of March 31, 2015 and December 31, 2014, respectively	42	42
Additional paid-in capital	429,816	421,630
Accumulated other comprehensive loss	-229	-120
Accumulated deficit	-145,649	-108,786
Total stockholders’ equity	283,980	312,766
Total liabilities and stockholders’ equity	$493,192	$539,265

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
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	42,141,742	42,002,533
Common stock, shares outstanding	42,141,742	42,002,533
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 $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenue	$104,334	$74,397
Costs and expenses:
Media costs	45,561	29,707
Other cost of revenue	19,956	7,828
Research and development	11,323	7,241
Sales and marketing	42,878	29,759
General and administrative	17,574	10,340
Total costs and expenses	137,292	84,875
Operating loss	-32,958	-10,478
Interest expense	1,340	414
Other (income) expense, net	2,208	19
Loss before income taxes	-36,506	-10,911
Income tax (benefit) provision	357	314
Net loss	($36,863)	($11,225)
Basic and diluted net loss per share attributable to common stockholders (in dollars per share)	($0.88)	($0.33)
Basic and diluted weighted-average shares used to compute net loss per share attributable to common stockholders (shares)	41,981	34,033

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	($36,863)		($11,225)
Other comprehensive loss:
Foreign currency translation adjustments	-109	[1]	32	[1]
Comprehensive loss	($36,972)		($11,193)
[1]	Reclassifications out of Other comprehensive income (loss) into Net loss were not significant.

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)				1,473,565
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 $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
OPERATING ACTIVITIES:
Net loss	($36,863)	($11,225)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	11,866	2,920
Stock-based compensation	7,447	5,125
Deferred taxes	285	0
Excess tax benefit from stock-based activity	0	-147
Other non-cash adjustments, net	509	84
Changes in operating assets and liabilities, net of effects of acquisition:
Accounts receivable	22,549	7,175
Prepaid expenses and other assets	5,379	-3,559
Accounts payable	-14,812	-5,004
Accrued and other liabilities	-4,271	-100
Deferred rent	1,184	3,570
Deferred revenue	2,530	-40
Net cash used in operating activities	-4,197	-1,201
INVESTING ACTIVITIES:
Purchases of property, equipment and software	-5,519	-7,177
Capitalized internal-use software development costs	-3,076	-1,757
Changes in restricted cash	636	-2,281
Net cash used in investing activities	-7,959	-11,215
FINANCING ACTIVITIES:
Proceeds from the issuance of common stock in initial and follow-on public offering, net of underwriting discounts, commission and issuance costs	0	115,525
Proceeds from employee stock plans, net	189	1,059
Excess tax benefit from stock-based activity	0	147
Repayment of capital lease obligations	-1,090	-38
Proceeds from debt facilities, net of debt issuance costs	-242	0
Repayment of debt	-1,500	0
Net cash (used in) provided by financing activities	-2,643	116,693
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	-202	24
CHANGE IN CASH AND CASH EQUIVALENTS	-15,001	104,301
CASH AND CASH EQUIVALENTS—Beginning of period	107,056	113,873
CASH AND CASH EQUIVALENTS—End of period	92,055	218,174
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Cash paid for income taxes, net of refunds	205	200
Cash paid for interest	914	347
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property and equipment recorded in accounts payable and accruals	623	5,585
Offering costs recorded in accrued liabilities	0	216
Property, plant and equipment acquired under capital lease obligations	325	1,769
Vesting of early exercised options	53	303
Stock-based compensation capitalized in internal-use software costs	$494	$403

NATURE_OF_BUSINESS_AND_SUMMARY

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	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.
	The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and the applicable rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in Consolidated Financial Statements prepared in accordance with GAAP have been condensed or omitted in accordance with such rules and regulations. The Condensed Consolidated Balance Sheet data as of December 31, 2014 was derived from audited financial statements, but does not include all disclosures required by GAAP. In the opinion of management, the accompanying unaudited Condensed Consolidated Financial Statements reflect all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of our financial position and our results of operations and cash flows.
	These Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2014.
	The significant accounting policies and recent accounting pronouncements were described in Note 1 to the Consolidated Financial Statements included in the 2014 Annual Report on Form 10-K for the fiscal year ended December 31, 2014. There have been no significant changes in or updates to the accounting policies since December 31, 2014 other than as presented below.
	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 four 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 March 31, 2015 and December 31, 2014, two agency holding companies and no single 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 three months ended March 31, 2015 and 2014, 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 three months ended March 31, 2015 and 2014.
	Goodwill—The Company performs an annual impairment test towards the end of its fiscal year on December 1 and whenever events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. During the quarter ended March 31, 2015, the market capitalization of its publicly traded common stock sustained a decline. The Company determined the decline to be a change in circumstance triggering the necessity to test its goodwill for impairment. Since the Company operates its business in one reporting unit, the goodwill is tested for impairment at the enterprise level.  Since the reporting unit's fair value based on quoted market prices of the Company's common stock was substantially in excess of its carrying value, it concluded that there has been no impairment of goodwill during the quarter ended March 31, 2015. If facts, circumstances or assumptions change in the future, the Company may be required to record impairment charges to reduce the carrying value of its goodwill.
	Recently Issued and Adopted Accounting Pronouncements
	On April 15, 2015, the FASB issued accounting guidance which clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software under ASC 350-40. The guidance is effective for annual periods and interim periods therein beginning after December 15, 2015. The adoption of this guidance will not have a material impact on the Company's consolidated financial statements.
	Other than the recent accounting pronouncements described in the Annual Report on Form 10-K for the fiscal year ended December 31, 2014, there have been no changes in accounting pronouncements since that date that are of significance or potential significance to the Company.

PROPERTY_EQUIPMENT_AND_SOFTWAR

PROPERTY, EQUIPMENT AND SOFTWARE, NET	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
PROPERTY, EQUIPMENT AND SOFTWARE, NET	PROPERTY, EQUIPMENT AND SOFTWARE, NET
	Property, equipment and software, net as of March 31, 2015 and December 31, 2014, consisted of the following (in thousands):
		March 31,			December 31,
		2015			2014
	Capitalized internal-use software costs	$	27,052		$	23,385
	Computer hardware and software	48,886			46,299
	Furniture and fixtures	13,498			11,674
	Leasehold improvements	38,646			36,811
	Total	128,082			118,169
	Accumulated depreciation and amortization	(36,330		)	(28,728		)
	Total property, equipment and software, net	$	91,752		$	89,441
	Total depreciation and amortization expense, excluding amortization of internal-use software costs, was $10.3 million and $1.8 million for the three months ended March 31, 2015 and 2014, respectively. Amortization expense of internal-use software costs was $1.6 million and $1.1 million for the three months ended March 31, 2015 and 2014, respectively. Refer to Note 4 for details of the Company's capital leases as of March 31, 2015 and December 31, 2014.

BUSINESS_COMBINATIONS

BUSINESS COMBINATIONS	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
BUSINESS COMBINATION	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. There were no changes in the carrying amount of goodwill during the three months ended March 31, 2015.
	The results of operations of [x+1] have been included in the Company's condensed 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 2014. The pro forma results include adjustments for amortization associated with the acquired intangible assets. 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):
			Three Months Ended
			March 31,
			2014
	Pro forma revenue		$	95,394
	Pro forma net loss		$	(17,835	)

CAPITAL_LEASES

CAPITAL LEASES	3 Months Ended
	Mar. 31, 2015
Leases [Abstract]
CAPITAL LEASES	CAPITAL LEASES
	Property and equipment includes hardware and software related to our data centers that are acquired under capital lease agreements. The remaining future minimum lease payments under these non-cancelable capital leases as of March 31, 2015 were as follows (in thousands):
	Year ending December 31,	Future Payments
	2015 (remaining 9 months)	$	4,874
	2016	6,498
	2017	4,812
	2018	2,103
	2019	79
	Thereafter	—
	Total minimum lease payments	$	18,366
	Less: amount representing interest and taxes	(1,519		)
	Less: current portion of minimum lease payments	(5,691		)
	Capital lease obligations, net of current portion	$	11,156

DEBT

DEBT	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
DEBT	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 that 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 March 31, 2015, $28.5 million in term loans, $40.0 million under the revolving credit facility and letters of credit in the amount of $7.0 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 2014 Loan Facility, plus a spread of 2.50% to 3.00%, or (ii) a LIBOR rate determined pursuant to the terms of the 2014 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 2014 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 owed 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 March 31, 2015, the Company was in compliance with all covenants.
	Future Payments
	Future principal payments of long-term debt as of March 31, 2015 were as follows (in thousands):
	Year ending December 31,	Future Payments
	2015 (remaining 9 months)	$	4,500
	2016	6,000
	2017	6,000
	2018	6,000
	2019	6,000
	Total	28,500
	Less: current portion of long-term debt	(6,000		)
	Long-term debt, net of current portion	$	22,500
	As of March 31, 2015, 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 condensed consolidated balance sheets. The debt on the condensed consolidated balance sheets is shown net of $0.9 million in debt issuance costs.

STOCKHOLDERS_EQUITY

STOCKHOLDERS' EQUITY	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS’ EQUITY
	The following table summarizes information pertaining to our stock-based compensation from stock options and stock awards, which are comprised of restricted stock awards and restricted stock units (in thousands, except grant-date fair value and recognition period):
		Three Months Ended			Three Months Ended
		March 31,			March 31,
		2015			2014
	Stock options:
	Outstanding at the beginning of the period	6,291			7,411
	Options granted	208			369
	Options exercised	(116		)	(288		)
	Options forfeited	(75		)	(74		)
	Outstanding at the end of the period	6,308			7,418
	Total intrinsic value of options exercised	$	858		$	15,324
	Total unrecognized compensation expense at period-end	$	23,190		$	32,200
	Weighted-average remaining recognition period at period-end	2.2			2.6
	Stock awards:
	Outstanding at the beginning of the period	2,515			382
	Stock awards granted	348			98
	Stock awards vested	(48		)	(4		)
	Stock awards canceled	(136		)	(3		)
	Outstanding at the end of the period	2,679			473
	Weighted-average grant-date fair value	$	16.74		$	51.16
	Total unrecognized compensation expense at period-end	$	41,131		$	19,100
	Weighted-average remaining recognition period at period-end	3.4			3.5
	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 March 31, 2015, 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 $1.5 million, which will be recognized over the offering period.
	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:
		Three Months Ended
		March 31,
		2015		2014
	Expected term (years)	6.3		6.3
	Volatility	58.00%		55.60%
	Risk-free interest rate	1.57%		1.85%
	Dividend yield	—		—
	The assumptions used to calculate our stock-based compensation for each stock purchase right granted under the ESPP were as follows:
		Three Months Ended
		March 31,
		2015		2014
	Expected term (years)	0.5		0.7
	Volatility	77.20%		66.20%
	Risk-free interest rate	0.08%		0.07%
	Dividend yield	—		—
	Stock-based compensation allocation
	The following table summarizes the allocation of stock-based compensation in the accompanying condensed consolidated statements of operations (in thousands):
		Three Months Ended
		March 31,
		2015			2014
	Other cost of revenue	$	625		$	252
	Research and development	2,247			987
	Sales and marketing	2,831			2,167
	General and administrative	1,744			1,551
	Total	$	7,447		$	4,957

NET_LOSS_PER_SHARE

NET LOSS PER SHARE	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
NET LOSS PER SHARE	NET LOSS PER SHARE
	Basic net 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. Because the Company had net losses for the three months ended March 31, 2015 and 2014, all these potentially dilutive shares of common stock were determined to be anti-dilutive and accordingly not included in the calculation of diluted net loss per share.
	The following table sets forth the computation of net loss per share of common stock (in thousands, except per share amounts):
		Three Months Ended
		March 31,
		2015			2014
	Net loss	$	(36,863	)	$	(11,225	)
	Weighted-average shares used to compute basic and diluted net loss per share	41,981			34,033
	Basic and diluted net loss per share	$	(0.88	)	$	(0.33	)
	Common stock equivalents excluded from net loss per diluted share because their effect would have been anti-dilutive	9,387			8,247

INCOME_TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES
	The Company is subject to income tax in the United States as well as other tax jurisdictions in which it conducts business. Earnings from non-U.S. activities are subject to local country income tax. The Company does not provide for federal income taxes on the undistributed earnings of its foreign subsidiaries as such earnings are intended to be reinvested indefinitely.
	The Company recorded income tax provisions of $0.4 million and $0.3 million for the three months ended March 31, 2015 and 2014, respectively, primarily due to foreign and state income tax expense. The primary difference between the effective tax rate and the federal statutory tax rate in the United States relates to the valuation allowances on the Company’s net operating losses, state and foreign tax rate differences, and research and development credits.
	Due to uncertainty as to the realization of benefits from deferred tax assets, including net operating loss carry-forwards, research and development and other tax credits, the Company has provided a full valuation allowance against such assets as of March 31, 2015 and December 31, 2014.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES
	Operating Leases—The Company has operating lease agreements for office space for administrative, 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 $4.0 million and $3.2 million for the three months ended March 31, 2015 and 2014, respectively.
	Approximate remaining future minimum cash lease payments under these non-cancelable operating leases as of March 31, 2015 were as follows (in thousands):
	Year ending December 31,	Future Payments
	2015 (remaining 9 months)	$	14,591
	2016	20,555
	2017	20,081
	2018	18,798
	2019	21,234
	Thereafter	44,800
		$	140,059
	Please refer to Note 4 for details of the Company's capital lease commitments as of March 31, 2015.
	Letters of Credit Bank Guarantees and Restricted Cash—As of March 31, 2015 and December 31, 2014, the Company had irrevocable letters of credit outstanding, with all financial institutions, in the amounts of $7.2 million and $6.8 million, respectively, for facilities leases. The letters of credit have various expiration dates, with the latest being December 2023.
	As of March 31, 2015, the Company had $2.2 million in cash reserved to support bank guarantees for certain office lease agreements. These amounts are classified as restricted cash on the Company's condensed 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 condensed consolidated balance sheets, condensed consolidated statements of operations, condensed consolidated statements of comprehensive loss, or condensed 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 its 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 in the Company's initial public offering on September 19, 2013 (the “IPO”) and its secondary offering on February 5, 2013 (the “Secondary Offering”) are also named as defendants. These actions were consolidated and a consolidated complaint, In re Rocket Fuel Securities Litigation, was filed on February 27, 2015. The consolidated complaint alleges 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 Rocket Fuel’s future prospects. The consolidated complaint also alleges that the Company's registration statements and prospectuses for the IPO and the Secondary Offering contained false and misleading statements on these topics. The consolidated complaint purports to assert claims for violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and SEC Rule 10b-5, and for violations of Sections 11 and 15 of the Securities Act of 1933, as amended (the “Securities Act”), 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 its initial public offering on September 19, 2013, and a claim for violation of Section 12(a)(2) of the Securities Act in connection with the Secondary Offering. The consolidated complaint seeks monetary damages in an unspecified amount. All defendants moved to dismiss the consolidated complaint on April 13, 2015. The Company intends to vigorously defend itself against this purported class action.
	On March 23, 2015, a purported shareholder derivative complaint for breach of fiduciary duty, waste of corporate assets, and unjust enrichment was filed in San Mateo, California Superior Court against certain of the Company's officers and its board of directors. The action is Davydov v. George H. John, et.al, Case No. CIV 53304. This state court action has been stayed pending the outcome of the defendants’ motions to dismiss in In re Rocket Fuel Securities Litigation.
	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	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
SEGMENTS	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):
		Three Months Ended
		March 31,
		2015		2014
	North America	$	88,249	$	62,647
	All Other Countries	16,085		11,750
	Total revenue	$	104,334	$	74,397
	The following table summarizes total long-lived assets in the respective locations (in thousands):
		March 31,		December 31,
		2015		2014
	North America	$	87,620	$	85,355
	All Other Countries	4,132		4,086
	Total long-lived assets	$	91,752	$	89,441

SUBSEQUENT_EVENTS

SUBSEQUENT EVENTS	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS
	On April 22, 2015, the Company announced a plan intended to improve its operational efficiency, which included a reduction of approximately 11% of its workforce, subletting of certain excess leased office space, and other cost reduction measures. The Company estimates that it will incur total cash expenses related to these actions of approximately $3 million, primarily related to one-time employee severance benefits. The Company also may incur an estimated $2 million to $3 million non-cash impairment charge for certain of its lease related assets, such as leasehold improvements. The Company expects to record the majority of these charges in the second quarter of 2015.

NATURE_OF_BUSINESS_AND_SUMMARY1

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
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 four 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 March 31, 2015 and December 31, 2014, two agency holding companies and no single 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 three months ended March 31, 2015 and 2014, 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.
Goodwill	Goodwill—The Company performs an annual impairment test towards the end of its fiscal year on December 1 and whenever events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. During the quarter ended March 31, 2015, the market capitalization of its publicly traded common stock sustained a decline. The Company determined the decline to be a change in circumstance triggering the necessity to test its goodwill for impairment. Since the Company operates its business in one reporting unit, the goodwill is tested for impairment at the enterprise level.  Since the reporting unit's fair value based on quoted market prices of the Company's common stock was substantially in excess of its carrying value, it concluded that there has been no impairment of goodwill during the quarter ended March 31, 2015. If facts, circumstances or assumptions change in the future, the Company may be required to record impairment charges to reduce the carrying value of its goodwill.
Recently Issued and Adopted Accounting Pronouncements	Recently Issued and Adopted Accounting Pronouncements
	On April 15, 2015, the FASB issued accounting guidance which clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software under ASC 350-40. The guidance is effective for annual periods and interim periods therein beginning after December 15, 2015. The adoption of this guidance will not have a material impact on the Company's consolidated financial statements.
	Other than the recent accounting pronouncements described in the Annual Report on Form 10-K for the fiscal year ended December 31, 2014, there have been no changes in accounting pronouncements since that date that are of significance or potential significance to the Company.

PROPERTY_EQUIPMENT_AND_SOFTWAR1

PROPERTY, EQUIPMENT AND SOFTWARE, NET (Tables)	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Schedule of property, equipment and software	Property, equipment and software, net as of March 31, 2015 and December 31, 2014, consisted of the following (in thousands):
		March 31,			December 31,
		2015			2014
	Capitalized internal-use software costs	$	27,052		$	23,385
	Computer hardware and software	48,886			46,299
	Furniture and fixtures	13,498			11,674
	Leasehold improvements	38,646			36,811
	Total	128,082			118,169
	Accumulated depreciation and amortization	(36,330		)	(28,728		)
	Total property, equipment and software, net	$	91,752		$	89,441

BUSINESS_COMBINATIONS_BUSINESS

BUSINESS COMBINATIONS BUSINESS COMBINATIONS (Tables)	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Schedule of Consideration For Business Acquisitions	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
Schedule of Purchase Price Allocation	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
	There were no changes in the carrying amount of goodwill during the three months ended March 31, 2015.
Pro Forma Information	in thousands):
			Three Months Ended
			March 31,
			2014
	Pro forma revenue		$	95,394
	Pro forma net loss		$	(17,835	)

CAPITAL_LEASES_Tables

CAPITAL LEASES (Tables)	3 Months Ended
	Mar. 31, 2015
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 March 31, 2015 were as follows (in thousands):
	Year ending December 31,	Future Payments
	2015 (remaining 9 months)	$	4,874
	2016	6,498
	2017	4,812
	2018	2,103
	2019	79
	Thereafter	—
	Total minimum lease payments	$	18,366
	Less: amount representing interest and taxes	(1,519		)
	Less: current portion of minimum lease payments	(5,691		)
	Capital lease obligations, net of current portion	$	11,156

DEBT_Tables

DEBT (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule of future principal payments of long-term debt	Future principal payments of long-term debt as of March 31, 2015 were as follows (in thousands):
	Year ending December 31,	Future Payments
	2015 (remaining 9 months)	$	4,500
	2016	6,000
	2017	6,000
	2018	6,000
	2019	6,000
	Total	28,500
	Less: current portion of long-term debt	(6,000		)
	Long-term debt, net of current portion	$	22,500

STOCKHOLDERS_EQUITY_Tables

STOCKHOLDERS' EQUITY (Tables)	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Summary of option award activity	The following table summarizes information pertaining to our stock-based compensation from stock options and stock awards, which are comprised of restricted stock awards and restricted stock units (in thousands, except grant-date fair value and recognition period):
		Three Months Ended			Three Months Ended
		March 31,			March 31,
		2015			2014
	Stock options:
	Outstanding at the beginning of the period	6,291			7,411
	Options granted	208			369
	Options exercised	(116		)	(288		)
	Options forfeited	(75		)	(74		)
	Outstanding at the end of the period	6,308			7,418
	Total intrinsic value of options exercised	$	858		$	15,324
	Total unrecognized compensation expense at period-end	$	23,190		$	32,200
	Weighted-average remaining recognition period at period-end	2.2			2.6
	Stock awards:
	Outstanding at the beginning of the period	2,515			382
	Stock awards granted	348			98
	Stock awards vested	(48		)	(4		)
	Stock awards canceled	(136		)	(3		)
	Outstanding at the end of the period	2,679			473
	Weighted-average grant-date fair value	$	16.74		$	51.16
	Total unrecognized compensation expense at period-end	$	41,131		$	19,100
	Weighted-average remaining recognition period at period-end	3.4			3.5
Schedule of assumptions used to value stock-based awards granted to employees	The assumptions used to value options granted to employees were as follows:
		Three Months Ended
		March 31,
		2015		2014
	Expected term (years)	6.3		6.3
	Volatility	58.00%		55.60%
	Risk-free interest rate	1.57%		1.85%
	Dividend yield	—		—
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:
		Three Months Ended
		March 31,
		2015		2014
	Expected term (years)	0.5		0.7
	Volatility	77.20%		66.20%
	Risk-free interest rate	0.08%		0.07%
	Dividend yield	—		—
	Stock-based compensation allocation
	The following table summarizes the allocation of stock-based compensation in the accompanying condensed consolidated statements of operations (in thousands):
		Three Months Ended
		March 31,
		2015			2014
	Other cost of revenue	$	625		$	252
	Research and development	2,247			987
	Sales and marketing	2,831			2,167
	General and administrative	1,744			1,551
	Total	$	7,447		$	4,957
	The assumptions used to calculate our stock-based compensation for each stock purchase right granted under the ESPP were as follows:
		Three Months Ended
		March 31,
		2015		2014
	Expected term (years)	0.5		0.7
	Volatility	77.20%		66.20%
	Risk-free interest rate	0.08%		0.07%
	Dividend yield	—		—

NET_LOSS_PER_SHARE_Tables

NET LOSS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Schedule of anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders
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):
		Three Months Ended
		March 31,
		2015			2014
	Net loss	$	(36,863	)	$	(11,225	)
	Weighted-average shares used to compute basic and diluted net loss per share	41,981			34,033
	Basic and diluted net loss per share	$	(0.88	)	$	(0.33	)
	Common stock equivalents excluded from net loss per diluted share because their effect would have been anti-dilutive	9,387			8,247

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2015
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 March 31, 2015 were as follows (in thousands):
	Year ending December 31,	Future Payments
	2015 (remaining 9 months)	$	14,591
	2016	20,555
	2017	20,081
	2018	18,798
	2019	21,234
	Thereafter	44,800
		$	140,059

SEGMENTS_Tables

SEGMENTS (Tables)	3 Months Ended
	Mar. 31, 2015
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):
		Three Months Ended
		March 31,
		2015		2014
	North America	$	88,249	$	62,647
	All Other Countries	16,085		11,750
	Total revenue	$	104,334	$	74,397
Schedule of total long-lived assets in the respective locations	The following table summarizes total long-lived assets in the respective locations (in thousands):
		March 31,		December 31,
		2015		2014
	North America	$	87,620	$	85,355
	All Other Countries	4,132		4,086
	Total long-lived assets	$	91,752	$	89,441

NATURE_OF_BUSINESS_AND_SUMMARY2

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (Customer concentration)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2012
	agency	agency	customer
Accounts receivable
Concentration of credit risk
Number of customers	2	2
Revenue
Concentration of credit risk
Number of customers	2	2	0

PROPERTY_EQUIPMENT_AND_SOFTWAR2

PROPERTY, EQUIPMENT AND SOFTWARE, NET (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Property, equipment and software
Total	$128,082,000		$118,169,000
Accumulated depreciation and amortization	-36,330,000		-28,728,000
Total property, equipment and software, net	91,752,000		89,441,000
Depreciation and amortization expense, excluding amortization of internal use software costs	10,300,000	1,800,000
Amortization expense	1,600,000	1,100,000
Capitalized internal-use software costs
Property, equipment and software
Total	27,052,000		23,385,000
Computer hardware and software
Property, equipment and software
Total	48,886,000		46,299,000
Furniture and fixtures
Property, equipment and software
Total	13,498,000		11,674,000
Leasehold improvements
Property, equipment and software
Total	$38,646,000		$36,811,000

BUSINESS_COMBINATIONS_Narrativ

BUSINESS COMBINATIONS - Narrative (Details) (USD $)	3 Months Ended		0 Months Ended	9 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Sep. 05, 2014	Sep. 30, 2013	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$115,412,000				$115,412,000
Tax benefit	357,000	314,000
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
Acquisition costs			4,900,000
Goodwill			114,871,000
Tax benefit				($4,100,000)

BUSINESS_COMBINATIONS_Schedule

BUSINESS COMBINATIONS - Schedule of Purchase Price Allocation (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Sep. 05, 2014
In Thousands, unless otherwise specified
Business Acquisition [Line Items]
Goodwill	$115,412	$115,412
Goodwill [Roll Forward]
Balance as of December 31, 2014	115,412	115,412
Balance as of March 31, 2015	115,412	115,412
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
Goodwill [Roll Forward]
Balance as of December 31, 2014			114,871
Balance as of March 31, 2015			$114,871

BUSINESS_COMBINATIONS_Intangib

BUSINESS COMBINATIONS - Intangible Assets Acquired (Details) (x Plus 1)	0 Months Ended
	Sep. 05, 2014
Trademarks
Business Acquisition [Line Items]
Estimated Useful Life (in years)	5 years
Non-compete agreements
Business Acquisition [Line Items]
Estimated Useful Life (in years)	2 years
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_Pro_Form

BUSINESS COMBINATIONS - Pro Forma (Details) (x Plus 1, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
x Plus 1
Business Acquisition [Line Items]
Pro forma revenue	$95,394
Pro forma net loss	($17,835)

CAPITAL_LEASES_Details

CAPITAL LEASES (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Approximate remaining future minimum lease payments under non-cancelable capital leases
2015 (remaining 9 months)	$4,874
2016	6,498
2017	4,812
2018	2,103
2019	79
Thereafter	0
Total minimum lease payments	18,366
Less: amount representing interest and taxes	-1,519
Less: current portion of minimum lease payments	-5,691	-5,482
Capital lease obligations, net of current portion	$11,156	$12,341

DEBT_Details

DEBT (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
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 (remaining 9 months)	4,500,000
2016	6,000,000
2017	6,000,000
2018	6,000,000
2019	6,000,000
Total	28,500,000
Long-term debt, net of current portion	21,907,000	23,335,000
Unamortized discounts	900,000
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	7,000,000
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	22,500,000
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	$28,500,000

STOCKHOLDERS_EQUITY_Details

STOCKHOLDERS' EQUITY (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
STOCKHOLDERS' EQUITY (DEFICIT)
Expected dividend payments	$0
Employee stock purchase plan
STOCKHOLDERS' EQUITY (DEFICIT)
Maximum employee subscription rate	15.00%
Purchase price of common stock, percent	85.00%
Total unrecognized compensation expense at period-end	$1,500,000

STOCKHOLDERS_EQUITY_Details_2

STOCKHOLDERS' EQUITY (Details 2) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013
Options
Number of Shares Outstanding
Balance at the beginning of the period (in shares)	6,291,000	7,411,000
Options granted (shares)	208,000	369,000
Options exercised (in shares)	-116,000	-288,000
Options forfeited (in shares)	-75,000	-74,000
Balance at the end of the period (in shares)	6,308,000	7,418,000
Additional Disclosures [Abstract]
Total intrinsic value of options exercised	$858	$15,324
Total unrecognized compensation expense at period-end	23,190		32,200
Weighted-average remaining recognition period at period-end	2 years 2 months 5 days	2 years 7 months 6 days
Restricted stock units (RSUs) and restricted stock awards (RSAs)
Number of Shares Outstanding
Balance at the beginning of the period (in shares)	2,515,000	382,000
Options granted (shares)	348,000	98,000
Options exercised (in shares)	-48,000	-4,000
Options forfeited (in shares)	-136,000	-3,000
Balance at the end of the period (in shares)	2,679,000	473,000
Additional Disclosures [Abstract]
Weighted-average grant-date fair value (dollars per share)	$16.74	$51.16
Total unrecognized compensation expense at period-end	$41,131		$19,100
Weighted-average remaining recognition period at period-end	3 years 4 months 28 days	3 years 5 months 23 days

STOCKHOLDERS_EQUITY_Details_3

STOCKHOLDERS' EQUITY (Details 3)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Employee stock purchase plan
Assumptions used to calculate stock-based compensation for each stock purchase right granted under the Employee Stock Purchase Plan (ESPP)
Expected term	0 years 6 months	8 months 12 days
Volatility (as a percent)	77.20%	66.20%
Risk-free interest rate (as a percent)	0.08%	0.07%
Dividend yield (as a percent)	0.00%	0.00%
Options
Assumptions used to calculate stock-based compensation for each stock purchase right granted under the Employee Stock Purchase Plan (ESPP)
Expected term	6 years 3 months 12 days	6 years 3 months 12 days
Volatility (as a percent)	58.00%	55.60%
Risk-free interest rate (as a percent)	1.57%	1.85%
Dividend yield (as a percent)	0.00%	0.00%

STOCKHOLDERS_EQUITY_Details_4

STOCKHOLDERS' EQUITY (Details 4) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	$7,447	$4,957
Cost of revenue
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	625	252
Research and development
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	2,247	987
Sales and marketing
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	2,831	2,167
General and administrative
Allocation of stock-based compensation and restricted stock for employees and non-employees
Total	$1,744	$1,551

NET_LOSS_PER_SHARE_Details

NET LOSS PER SHARE (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Computation of net loss per common share
Net loss	($36,863)	($11,225)	($64,311)	($20,932)	($10,343)
Weighted-average shares used to compute basic and diluted net loss per share (shares)	41,981	34,033
Basic and diluted net loss per share (in dollars per share)	($0.88)	($0.33)
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)	9,387	8,247

INCOME_TAXES_Details

INCOME TAXES (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Income tax (benefit) provision	($357)	($314)

COMMITMENTS_AND_CONTINGENCIES_1

COMMITMENTS AND CONTINGENCIES (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Operating Leases
Rent expense	$4,000,000	$3,200,000
Future minimum lease payments under non-cancelable operating leases
2015 (remaining 9 months)	14,591,000
2016	20,555,000
2017	20,081,000
2018	18,798,000
2019	21,234,000
Thereafter	44,800,000
Total future payments	140,059,000
Letters of Credit and Bank Guarantees
Irrevocable letters of credit outstanding	7,200,000		6,800,000
Bank guarantees for security deposits	$2,188,000		$2,915,000

SEGMENTS_Details

SEGMENTS (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	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
Segments
Total revenue	$104,334	$74,397
Total long-lived assets	91,752		89,441
North America
Segments
Total revenue	88,249	62,647
Total long-lived assets	87,620		85,355
All Other Countries
Segments
Total revenue	16,085	11,750
Total long-lived assets	$4,132		$4,086

SUBSEQUENT_EVENTS_SUBSEQUENT_E

SUBSEQUENT EVENTS SUBSEQUENT EVENTS (Details) (Subsequent Event, USD $)	0 Months Ended
In Millions, unless otherwise specified	Apr. 22, 2015
Subsequent Event [Line Items]
Restructuring and Related Cost, Expected Percent of Positions Eliminated	11.00%
One-time Termination Benefits
Subsequent Event [Line Items]
Restructuring and Related Cost, Expected Cost	$3
Facility Closing | Minimum
Subsequent Event [Line Items]
Restructuring and Related Cost, Expected Cost	2
Facility Closing | Maximum
Subsequent Event [Line Items]
Restructuring and Related Cost, Expected Cost	$3