Constant Contact (CTCT) 10-K 25 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 20, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	CTCT
Entity Registrant Name	Constant Contact, Inc.
Entity Central Index Key	1405277
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		32,131,876
Entity Public Float			$993,927,578

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets
Cash and cash equivalents	$104,301	$82,478
Marketable securities	58,321	40,723
Accounts receivable, net of allowance for doubtful accounts	265	180
Prepaid expenses and other current assets	10,723	9,175
Total current assets	173,610	132,556
Property and equipment, net	43,739	39,238
Restricted cash	1,300	1,300
Goodwill	95,505	95,505
Acquired intangible assets, net	2,160	4,355
Deferred taxes	4,658	9,574
Other assets	1,893	2,345
Total assets	322,865	284,873
Current liabilities
Accounts payable	4,703	6,783
Accrued expenses	12,230	10,903
Deferred revenue	37,838	35,256
Total current liabilities	54,771	52,942
Other long-term liabilities	3,783	2,060
Total liabilities	58,554	55,002
Commitments and contingencies (Note 10)
Stockholders' equity
Preferred stock; $0.01 par value; 5,000,000 shares authorized; no shares issued or outstanding at December 31, 2014 and 2013
Common stock; $0.01 par value; 100,000,000 shares authorized; 31,908,622 and 31,203,585 shares issued and outstanding at December 31, 2014 and 2013, respectively	319	312
Additional paid-in capital	249,599	229,457
Accumulated other comprehensive income (loss)	-10	14
Retained earnings	14,403	88
Total stockholders' equity	264,311	229,871
Total liabilities and stockholders' equity	$322,865	$284,873

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Preferred stock, par value	$0.01	$0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	31,908,622	31,203,585
Common stock, shares outstanding	31,908,622	31,203,585

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	$331,678	$285,383	$252,154
Cost of revenue	91,063	81,616	73,547
Gross profit	240,615	203,767	178,607
Operating expenses:
Research and development	53,086	45,567	38,787
Sales and marketing	125,809	111,374	104,527
General and administrative	41,919	38,531	31,132
Acquisition costs and other related charges			-11,355
Total operating expenses	220,814	195,472	163,091
Income from operations	19,801	8,295	15,516
Interest income	144	94	224
Other income (expense), net	172	81	7
Income before income taxes	20,117	8,470	15,747
Income tax expense	-5,802	-1,256	-3,181
Net income	$14,315	$7,214	$12,566
Net income per share:
Basic	$0.45	$0.23	$0.41
Diluted	$0.44	$0.23	$0.41
Weighted average shares outstanding used in computing per share amounts:
Basic	31,619	30,730	30,386
Diluted	32,836	31,356	31,003

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$14,315	$7,214	$12,566
Other comprehensive income:
Net unrealized losses on marketable securities, net of tax	-13	-1	-51
Reclassification adjustment for realized gains on available-for-sale securities included in net income	-1
Translation adjustment	-11	4	1
Total other comprehensive income (loss)	-25	3	-50
Comprehensive income	$14,290	$7,217	$12,516

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Stockholders` Equity (USD $)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings (Accumulated Deficit) [Member]
In Thousands, except Share data
Beginning balance at Dec. 31, 2011	$170,480	$301	$189,810	$61	($19,692)
Beginning balance, shares at Dec. 31, 2011		30,110,895
Issuance of common stock in connection with stock option and warrant exercises	4,355	4	4,351
Issuance of common stock in connection with stock option and warrant exercises, shares		415,136
Issuance of common stock pursuant to vesting of restricted stock units	-596	1	-597
Issuance of common stock pursuant to vesting of restricted stock units, shares		47,263
Issuance of common stock in connection with employee stock purchase plan	1,053	1	1,052
Issuance of common stock in connection with employee stock purchase plan, shares		78,081
Stock-based compensation expense	15,059		15,059
Unrealized loss on available-for-sale securities	-51			-51
Translation adjustment	1			1
Net income	12,566				12,566
Ending balance at Dec. 31, 2012	202,867	307	209,675	11	-7,126
Ending balance, shares at Dec. 31, 2012		30,651,375
Issuance of common stock in connection with stock option and warrant exercises	10,446	6	10,440
Issuance of common stock in connection with stock option and warrant exercises, shares		671,596
Issuance of common stock pursuant to vesting of restricted stock units	-1,591	1	-1,592
Issuance of common stock pursuant to vesting of restricted stock units, shares		87,058
Issuance of common stock in connection with employee stock purchase plan	1,089	1	1,088
Issuance of common stock in connection with employee stock purchase plan, shares		79,456
Repurchase and retirement of common stock	-5,366	-3	-5,363
Repurchase and retirement of common stock, shares		-285,900
Stock-based compensation expense	15,213		15,213
Income tax from the exercise of stock options	-4		-4
Unrealized loss on available-for-sale securities	-1			-1
Translation adjustment	4			4
Net income	7,214				7,214
Ending balance at Dec. 31, 2013	229,871	312	229,457	14	88
Ending balance, shares at Dec. 31, 2013	31,203,585	31,203,585
Issuance of common stock in connection with stock option and warrant exercises	20,162	12	20,150
Issuance of common stock in connection with stock option and warrant exercises, shares	1,039,200	1,039,713
Issuance of common stock pursuant to vesting of restricted stock units	-3,023	1	-3,024
Issuance of common stock pursuant to vesting of restricted stock units, shares		149,881
Issuance of common stock in connection with employee stock purchase plan	1,863		1,863
Issuance of common stock in connection with employee stock purchase plan, shares		69,109
Repurchase and retirement of common stock	-16,361	-6	-16,355
Repurchase and retirement of common stock, shares	-553,666	-553,666
Stock-based compensation expense	16,850		16,850
Income tax from the exercise of stock options	658		658
Unrealized loss on available-for-sale securities	-13			-13
Translation adjustment	-11			-11
Net income	14,315				14,315
Ending balance at Dec. 31, 2014	$264,311	$319	$249,599	($10)	$14,403
Ending balance, shares at Dec. 31, 2014	31,908,622	31,908,622

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
Cash flows from operating activities
Net income	$14,315	$7,214	$12,566
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	24,164	22,191	19,003
Amortization of premium on investments	262	210	539
Stock-based compensation expense	16,650	14,731	14,274
Provision for bad debts		14	11
Gain on sales of marketable securities	-1
Deferred taxes	4,094	885	2,738
Contingent consideration adjustment			-12,152
Income tax benefit from the exercise of stock options	-984	-123	-84
Taxes paid related to net share settlement of restricted stock units	-3,024	-1,592	-597
Loss on sublease	259
Changes in operating assets and liabilities, net of effects from acquisition:
Accounts receivable	-85	-102	3
Prepaid expenses and other current assets	-59	-2,454	2,169
Other assets	452	762	-653
Accounts payable	-3,138	-1,384	-787
Accrued expenses	404	100	-1,398
Deferred revenue	2,582	2,556	3,107
Other long-term liabilities	1,523	50	-42
Net cash provided by operating activities	57,414	43,058	38,697
Cash flows from investing activities
Purchases of marketable securities	-36,582	-30,739	-40,254
Proceeds from maturities of marketable securities	18,065	11,534	59,867
Proceeds from sales of marketable securities	633	4,000	44,600
Acquisition of businesses, net of cash acquired			-68,296
Net increase in restricted cash		-550
Acquisition of property and equipment, including costs capitalized for development of internal use software	-24,347	-18,891	-21,922
Net cash used in investing activities	-42,231	-34,646	-26,005
Cash flows from financing activities
Proceeds from issuance of common stock pursuant to exercise of stock options and warrants	20,162	10,447	4,356
Income tax benefit from the exercise of stock options	984	119	84
Proceeds from issuance of common stock pursuant to employee stock purchase plan	1,864	1,089	1,053
Repurchase of common stock	-16,361	-5,366
Net cash provided by financing activities	6,649	6,289	5,493
Effects of exchange rates on cash	-9	2	1
Net increase in cash and cash equivalents	21,823	14,703	18,186
Cash and cash equivalents, beginning of year	82,478	67,775	49,589
Cash and cash equivalents, end of year	104,301	82,478	67,775
Supplemental disclosure of cash flow information
Cash paid for income taxes	1,031	523	61
Supplemental disclosure of noncash investing and financing activities:
Capitalization of stock-based compensation	200	482	785
Acquisition of property and equipment included in accounts payable and accrued expenses	1,923
Fair value of contingent consideration recorded at the time of acquisition in accrued expenses and other long-term liabilities			$12,152

Nature_of_the_Business

Nature of the Business	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Nature of the Business	1.    Nature of the Business
	Constant Contact, Inc. (the “Company”) was incorporated as a Massachusetts corporation in 1995 and was reincorporated in the State of Delaware in 2000. The Company is a leading provider of online marketing tools that are designed for small organizations, including small businesses, associations and non-profits. The Company seeks to help customers succeed by creating and growing their customer and member relationships through easy-to-use products combined with education, support, KnowHow® and coaching. In April 2014, the Company formally launched Constant Contact Toolkit™, an integrated online marketing platform that simplifies small business marketing by bringing together the tools needed to drive repeat customers and reach new ones. The Company also offers a suite of online marketing tools, including Email Marketing, EventSpot®, Social Campaigns™, SaveLocal™, SinglePlatform and Survey, that enables customers to launch and monitor marketing campaigns across multiple channels, including email, social media, events, local deals, online listings and surveys. These products are marketed and sold directly by the Company and through a wide variety of partners primarily in the United States of America.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2.    Summary of Significant Accounting Policies
	Basis of Presentation
	The accompanying consolidated financial statements include those of the Company and its subsidiaries, after elimination of all intercompany accounts and transactions. The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”).
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. On an ongoing basis, management evaluates these estimates, judgments and assumptions, including those related to revenue recognition, stock-based compensation, goodwill and acquired intangible assets, capitalization of software and website development costs and income taxes. The Company bases these estimates on historical and anticipated results and trends and on various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenue and expenses that are not readily apparent from other sources. Actual results could differ from these estimates.
	Fair Value of Financial Instruments
	Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. A fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last is considered unobservable, are used to measure fair value:
		•		Level 1—Quoted prices in active markets for identical assets or liabilities.
		•		Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
		•		Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	During the years ended December 31, 2014, 2013 and 2012, there were no transfers between Level 1, Level 2 and Level 3.
	The following tables present the Company’s fair value hierarchy for its assets, which are measured at fair value on a recurring basis as of December 31, 2014 and 2013:
			Fair Value Measurements at December 31, 2014 Using
			Level 1			Level 2		Level 3			Total
	Financial Assets:
	Money Market Instruments		$	5,885		$	—	$	—		$	5,885
	United States Treasury Notes			20,006			—		—			20,006
	Corporate and Agency Bonds			—			37,316		—			37,316
	Commercial Paper			—			999		—			999
	Total		$	25,891		$	38,315	$	—		$	64,206
			Fair Value Measurements at December 31, 2013 Using
			Level 1			Level 2		Level 3			Total
	Financial Assets:
	Money Market Instruments		$	23,444		$	—	$	—		$	23,444
	United States Treasury Notes			27,035			—		—			27,035
	Corporate and Agency Bonds			—			12,688		—			12,688
	Commercial Paper			—			1,000		—			1,000
	Total		$	50,479		$	13,688	$	—		$	64,167
	The Company had a contingent consideration liability associated with the acquisition of SinglePlatform, Corp. (“SinglePlatform”) in June 2012, which had been assessed at $0 as of December 31, 2013. The final measurement period for achievement of the goals related to the contingent consideration ended on June 30, 2014 and resulted in no payout of consideration. Prior to June 30, 2014, contingent consideration was measured at fair value and was based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy. The valuation of the contingent consideration liability used assumptions and estimates to forecast a range of outcomes for the contingent consideration. The Company assessed these assumptions and estimates on a quarterly basis as additional data impacting the assumptions was obtained. Changes in the fair value of the contingent consideration liability related to updated assumptions and estimates were recognized within the consolidated statements of operations. There were no changes to the fair value of the contingent consideration liability for either of the years ended December 31, 2014 or 2013. The change in the fair value of the contingent consideration liability from the date of the SinglePlatform acquisition through December 31, 2012 resulted from reductions to the SinglePlatform revenue forecast scenarios. The revenue forecast scenarios were decreased due to SinglePlatform’s actual operating results and reduced productivity of its sales organization during 2012.
	Changes in the fair value of the Level 3 contingent consideration liability associated with the SinglePlatform acquisition were as follows:
			Contingent Consideration
			Liability
	Acquisition of SinglePlatform in June 2012		$	12,152
	Change in fair value of contingent consideration liability, included in acquisition costs and other related charges in 2012			(12,152	)
	Balance at December 31, 2012, 2013 and 2014		$	—
	Fair Value Option for Financial Assets and Financial Liabilities
	Authoritative guidance allows companies to choose to measure many financial instruments and certain other items at fair value. The Company has elected not to apply the fair value option to any of its financial assets or liabilities.
	Cash and Cash Equivalents
	The Company considers all highly liquid investments with original maturities of three months or less at the time of acquisition to be cash equivalents. The Company also considers receivables related to customer credit card purchases of $1,502 and $2,901 at December 31, 2014 and 2013, respectively, to be equivalent to cash. Cash equivalents are stated at fair value.
	Marketable Securities
	The Company’s marketable securities are classified as available-for-sale and are carried at fair value with the unrealized gains and losses reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Realized gains and losses and declines in value judged to be other than temporary are included as a component of other income (expense), net based on the specific identification method. Fair value is determined based on quoted market prices. At December 31, 2014, marketable securities by security type consisted of:
			Amortized			Gross		Gross			Estimated
			Cost			Unrealized		Unrealized			Fair
						Gains		Losses			Value
	United States Treasury Notes		$	20,000		$	6	$	—		$	20,006
	Corporate and Agency Bonds			37,330			2		(16	)		37,316
	Commercial Paper			999			—		—			999
	Total		$	58,329		$	8	$	(16	)	$	58,321
	At December 31, 2014, marketable securities consisted of investments that mature within one year with the exception of government treasuries and corporate and agency bonds with a fair value of $6,644, which have maturities within two years.
	At December 31, 2013, marketable securities by security type consisted of:
			Amortized			Gross		Gross			Estimated
			Cost			Unrealized		Unrealized			Fair
						Gains		Losses			Value
	United States Treasury Notes		$	27,022		$	13	$	—		$	27,035
	Corporate and Agency Bonds			12,684			4		—			12,688
	Commercial Paper			1,000			—		—			1,000
	Total		$	40,706		$	17	$	—		$	40,723
	Accounts Receivable
	Management reviews accounts receivable on a periodic basis to determine if any receivables will potentially be uncollectible. The Company reserves for receivables that are determined to be uncollectible, if any, in its allowance for doubtful accounts. After the Company has exhausted all collection efforts, the outstanding receivable is written off against the allowance.
	Concentration of Credit Risk and Significant Products and Customers
	Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. At December 31, 2014 and 2013, the Company had substantially all cash balances at certain financial institutions without or in excess of federally insured limits, however, the Company maintains its cash balances and custody of its marketable securities with accredited financial institutions. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.
	For the years ended December 31, 2014, 2013 and 2012, revenue from the Company’s email marketing product alone as a percentage of total revenue was approximately 80%, 84% and 85%, respectively. No customer accounted for more than 10% of total revenue during these years.
	Goodwill and Acquired Intangible Assets
	The Company records goodwill when consideration paid in a business acquisition exceeds the fair value of the net tangible assets and the identified intangible assets acquired. Goodwill is not amortized, but rather is tested for impairment annually or more frequently if facts and circumstances warrant a review. The Company performs its annual assessment for impairment of goodwill on November 30th of each year and has determined that there is a single reporting unit for the purpose of conducting this annual goodwill impairment assessment. For purposes of assessing potential impairment, the Company annually estimates the fair value of the reporting unit (based on the Company’s market capitalization) and compares this amount to the carrying value of the reporting unit (as reflected by the Company’s total stockholders’ equity). If the Company determines that the carrying value of the reporting unit exceeds its fair value, an impairment charge would be required.
Intangible assets are recorded at their estimated fair values at the date of acquisition. The Company amortizes acquired intangible assets over their estimated useful lives based on the pattern of consumption of the economic benefits or, if that pattern cannot be readily determined, on a straight-line basis.
Property and Equipment
Property and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful life of the assets or, where applicable and if shorter, over the lease term. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are eliminated from the accounts and any resulting gain or loss is credited or charged to the statement of operations. Repairs and maintenance costs are expensed as incurred.
Estimated useful lives of assets are as follows:
Computer equipment		3 years
Software		3 years
Furniture and fixtures		5 years
Leasehold improvements		Shorter of life of lease or
		estimated useful life
Long-Lived Assets
The Company reviews the carrying values of its long-lived assets for possible impairment when events or changes in circumstance indicate that the related carrying amount may not be recoverable. Undiscounted cash flows are compared to the carrying value and when required, impairment losses on assets to be held and used are recognized based on the excess of the asset’s carrying amount over the fair value of the asset. Long-lived assets to be disposed of are reported at the lower of carrying amount or fair value less cost to sell.
Revenue Recognition
The Company provides access to its products primarily through subscription arrangements whereby the customer is charged a fee for access for a defined term. Subscription arrangements include access to use the Company’s software via the Internet and support services, such as telephone, email and chat support. When there is evidence of an arrangement, the fee is fixed or determinable and collectability is deemed reasonably assured, the Company recognizes revenue on a daily basis over the subscription period as the services are delivered. Delivery is considered to have commenced at the time the customer has paid for the products and has access to the account via a log-in and password. The Company also offers ancillary services to its customers related to its subscription-based products such as custom services and training. When sold together, revenue from custom services, training and subscription products are accounted for separately based on vendor-specific objective evidence of fair value of each of the services as those services have value on a standalone basis and do not involve a significant degree of risk or unique acceptance criteria. Revenue from custom services and training is recognized as the services are performed. Revenue from transaction-based products and services is recognized based on the transactional fee charged when there is evidence of an arrangement, the fee is fixed or determinable, collectability is deemed reasonably assured and the transaction has occurred.
Deferred Revenue
Deferred revenue consists of payments received in advance of delivery of the Company’s on-demand products described above and is recognized as the revenue recognition criteria are met. The Company’s customers generally pay for services in advance on a monthly, semiannual or annual basis.
Software and Website Development Costs
Research and development costs are expensed as incurred and primarily include salaries, fees to consultants, and other related costs. Relative to development costs of its on-demand products and website, the Company capitalizes certain direct costs to develop functionality as well as certain upgrades and enhancements that are probable to result in additional functionality. The costs incurred in the preliminary stages of development are expensed as incurred. Once an application has reached the development stage, internal and external costs, if direct and incremental, are capitalized as part of property and equipment until the software is substantially complete and ready for its intended use. Capitalized software is amortized over a three-year period in the expense category to which the software relates.
Foreign Currency Translation
The functional currency of the Company’s operations in the United Kingdom is deemed to be the British pound. Accordingly, the assets and liabilities of the Company’s United Kingdom subsidiary are translated into United States dollars using the period-end exchange rate, and income and expense items are translated using the average exchange rate during the period. Cumulative translation adjustments are reflected as a separate component of stockholders’ equity. Foreign currency transaction gains and losses are charged to Other income (expense), net and were not material to the Company’s operations.
Comprehensive Income
Comprehensive income includes net income, as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The Company’s only elements of other comprehensive income (loss) are unrealized gains and losses on available-for-sale securities and translation adjustments.
Segment Data
The Company manages its operations as a single segment for purposes of assessing performance and making operating decisions. Revenue is generated predominately in the United States and all significant assets are held in the United States.
Net Income Per Share
Basic net income per share is computed by dividing net income by the weighted average number of unrestricted common shares outstanding during the period.
Diluted net income per share is computed by dividing net income by the sum of the weighted average number of unrestricted common shares outstanding during the period and the weighted average number of potential common shares from the assumed exercise of stock options and the vesting of shares of restricted common stock and restricted stock units using the “treasury stock” method when the effect is not anti-dilutive.
The following is a summary of the shares used in computing diluted net income per share:
		Years ended December 31,
		2014			2013		2012
		(in thousands)
Weighted average shares used in calculating basic net income per share			31,619			30,730		30,386
Stock options			1,100			524		581
Warrants			—			1		1
Unvested restricted stock and restricted stock units			117			101		35
Shares used in computing diluted net income per share			32,836			31,356		31,003
The Company excluded the following common stock equivalents from the computation of diluted net income per share because they had an anti-dilutive impact because the proceeds under the treasury stock method were in excess of the average fair market value for the period:
		Years ended December 31,
		2014			2013		2012
		(in thousands)
Options to purchase common stock			1,278			3,586		3,342
Unvested restricted stock and restricted stock units			200			176		110
Total options exercisable into common stock, restricted stock units issuable in common stock and restricted stock			1,478			3,762		3,452
Advertising Expense
The Company expenses advertising as incurred. Advertising expense was $42,234, $39,796 and $35,350 during the years ended December 31, 2014, 2013 and 2012, respectively.
Accounting for Stock-Based Compensation
The Company values all stock-based compensation, including grants of stock options, restricted stock and restricted stock units, at fair value on the date of grant, and expenses the fair value over the applicable service period. The straight-line method is applied to all grants with service and market conditions, while the graded vesting method is applied to all grants with both service and performance conditions.
Income Taxes
Income taxes are provided for tax effects of transactions reported in the financial statements and consist of income taxes currently due plus deferred income taxes related to timing differences between the basis of certain assets and liabilities for financial statement and income tax reporting purposes. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance is provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.
The Company accounts for uncertainty in income taxes recognized in the financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination. If the tax position is deemed “more-likely-than-not” to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement.
Recently Issued Accounting Pronouncements
In May 2014, the Financial Accounting Standards Board (“FASB”) issued new guidance, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. This guidance will replace most existing revenue recognition guidance in GAAP when it becomes effective. The guidance also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The new guidance is effective for the Company commencing January 1, 2017. Early application is not permitted. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that this guidance will have on its consolidated financial statements.
In August 2014, FASB issued new guidance, Presentation of Financial Statements—Going Concern. The new guidance addresses management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. Management’s evaluation should be based on relevant conditions and events that are known and reasonably knowable at the date that the financial statements are issued. The standard will be effective for the first interim period within annual reporting periods beginning after December 15, 2016. Early adoption is permitted. The Company is evaluating the effect that this guidance will have on its consolidated financial statements.

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property and Equipment	3	Property and Equipment
	Property and equipment consisted of the following:
		December 31,
		2014		2013
	Computer equipment	$	51,439	$	52,059
	Software		50,590		43,377
	Furniture and fixtures		8,634		8,599
	Leasehold improvements		16,340		11,657
	Total property and equipment		127,003		115,692
	Less: Accumulated depreciation and amortization		83,264		76,454
	Property and equipment, net	$	43,739	$	39,238
	Depreciation and amortization expense was $21,969, $19,788 and $17,331 for the years ended December 31, 2014, 2013 and 2012, respectively. In 2014, the Company disposed of assets with a gross book value of $15,159 which were fully depreciated at the time of disposal.
	The Company capitalized costs associated with the development of internal use software of $7,892, $7,411 and $6,673 included in Software line item above and recorded related amortization expense of $6,689, $4,575 and $3,383 (included in depreciation and amortization expense) during the years ended December 31, 2014, 2013 and 2012, respectively. The remaining net book value of capitalized software costs was $15,299 and $14,096 as of December 31, 2014 and 2013, respectively.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Acquisitions	4.    Acquisitions
	CardStar
	On January 13, 2012, the Company acquired by merger all of the outstanding capital stock of CardStar, Inc. (“CardStar”) for a cash purchase price of $5,750. CardStar was a leading developer of mobile applications that extend the use of loyalty, rewards and membership cards and mobile coupons among consumers. The Company purchased CardStar in order to accelerate its entrance into the mobile marketing and loyalty space.
	The Company allocated the purchase price as follows:
	Developed technology	$	624
	Net deferred tax assets		553
	Goodwill		4,573
	Total assets acquired	$	5,750
	The developed technology was valued using the cost to replace method and has an estimated economic life of three years.
	Goodwill was recognized for the excess purchase price over the fair value of the assets acquired. Goodwill is primarily attributable to CardStar’s knowledge of mobile applications and coupons and loyalty, rewards and membership cards. Goodwill from the CardStar acquisition is included within the Company’s one reporting unit and is included in the Company’s enterprise-level annual review for impairment. Goodwill resulting from the acquisition of CardStar is not deductible for tax purposes.
	SinglePlatform
	On June 12, 2012, the Company acquired by merger all of the outstanding capital stock of SinglePlatform. SinglePlatform provided small businesses a single place to update their business information and delivered that information across its publishing network. The Company purchased SinglePlatform in order to expand its product offerings and allow small organizations to engage their customers earlier in the customer lifecycle. The purchase price of $75,009 reflected a cash payment of $62,857 and a liability of $12,152 representing the fair value of contingent consideration of up to $30,000 payable to the former shareholders of SinglePlatform upon achievement by SinglePlatform of certain revenue targets. These revenue targets were to be measured in six month intervals from July 1, 2012 to June 30, 2014. If such targets were achieved, the consideration was payable in cash. Using a discounted cash flow method and a probability weighted estimate of future revenue, the Company recorded an estimated liability of $12,152 as of the acquisition date. The estimated undiscounted range of outcomes for the contingent consideration was $0 to $21,095 at the acquisition date. The first revenue target, assessed at December 31, 2012 was not met and, based on actual results and the impact to forecasted performance, the Company revised its revenue forecasts in 2012. Under the revised forecasts, no contingent consideration payments were to be made. Accordingly, the Company recorded a reduction to expenses of $12,152 in 2012 relating to this remeasurement of the fair value of the contingent liability. The reduction is included in acquisition costs and other related charges in the Company’s consolidated statement of operations for the year ended December 31, 2012. The second, third and fourth revenue targets, measured at June 30, 2013, December 31, 2013 and June 30, 2014, respectively, were also not met; therefore no payments were made and the liability is considered fully settled as of December 31, 2014.
	The following table summarizes the purchase price for SinglePlatform and the allocation of the purchase price:
	Purchase consideration:
	Total cash paid, net of cash acquired	$	62,546
	Cash acquired		311
	Fair value of contingent consideration		12,152
	Total purchase price consideration	$	75,009
	Assets acquired and liabilities assumed:
	Cash	$	311
	Accounts receivable		48
	Prepaid expenses and other current assets		60
	Property and equipment		14
	Identifiable intangible assets		4,760
	Other assets		91
	Net deferred tax assets		72
	Goodwill		71,997
	Total assets acquired		77,353
	Accounts payable, accrued expenses and other current liabilities		(1,734	)
	Deferred revenue		(610	)
	Total liabilities assumed		(2,344	)
	Total allocation of purchase price consideration	$	75,009
	The developed technology and the customer and publisher relationships were valued using the cost to replace method. The trade name was valued using the relief from royalty method. Acquired intangible assets are amortized over their estimated useful lives based on the pattern of consumption of the economic benefits or, if that pattern cannot be readily determined, on a straight-line basis. The following table presents the estimated fair values and useful lives of identifiable intangible assets acquired:
		Amount			Weighted Average Useful
					Life
					(in years)
	Developed technology	$	850			3
	Customer relationships		2,630			3.75
	Publisher relationships		710			5
	Trade name		570			5
	Total identifiable intangible assets	$	4,760			3.95
	Goodwill was recognized for the excess purchase price over the fair value of the net assets acquired. Goodwill is primarily attributable to the workforce of the acquired business (which is not eligible for separate recognition as an identifiable intangible asset) and the expected synergistic benefits of being able to market SinglePlatform’s product to the Company’s customer base and being able to market the Company’s products to SinglePlatform’s customer base. Goodwill from the SinglePlatform acquisition is included within the Company’s one reporting unit and is included in the Company’s enterprise-level annual review for impairment. Goodwill resulting from the acquisition of SinglePlatform is not deductible for tax purposes.
	The following table presents the pro forma results of the historical consolidated statements of operations of the Company and SinglePlatform for the year ended December 31, 2012, giving effect to the merger as if it occurred on January 1, 2011:
		Year ended
		December 31,
		2012
	Pro forma revenue	$	252,618
	Pro forma net income	$	11,173
	The pro forma net income presented primarily includes adjustments for amortization, elimination of transaction costs, interest income and income taxes. This pro forma information does not purport to indicate the results that would have actually been obtained had the acquisition been completed on the assumed date, or which may be realized in the future.
	There were no transaction costs for the years ended December 31, 2014 and 2013. Transaction costs related to the CardStar and SinglePlatform acquisitions were $797 for the year ended December 31, 2012, which the Company recorded as acquisition costs and other related charges. The operating expenses of the acquired entities have been included in the consolidated financial statements beginning on their respective acquisition dates but have not been disclosed as the Company does not account for the results of the acquired entities separate from its own results.

Goodwill_and_Acquired_Intangib

Goodwill and Acquired Intangible Assets	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Acquired Intangible Assets	5.    Goodwill and Acquired Intangible Assets
	The carrying amount of goodwill was $95,505 as of December 31, 2014 and 2013.
	Goodwill is not amortized, but instead is reviewed for impairment at least annually in the fourth quarter or more frequently when events and circumstances occur indicating that the recorded goodwill may be impaired. The Company considers its business to be one reporting unit for purposes of performing its goodwill impairment analysis. The Company completed its most recent annual impairment test of goodwill on November 30, 2014. To date, the Company has had no impairments of goodwill.
	Intangible assets consist of the following:
		Estimated		December 31, 2014						December 31, 2013
		Useful Life		Gross		Accumulated		Net Carrying		Gross		Accumulated		Net Carrying
				Carrying		Amortization		Amount		Carrying		Amortization		Amount
				Amount						Amount
	Developed technology		3 years	$	4,357	$	3,465	$	892	$	4,357	$	2,336	$	2,021
	Customer relationships		3.75 years		3,315		2,666		649		3,315		1,855		1,460
	Publisher relationships		5 years		710		367		343		710		225		485
	Trade name		5 years		570		294		276		570		181		389
				$	8,952	$	6,792	$	2,160	$	8,952	$	4,597	$	4,355
	The Company amortizes the intangible assets over the estimated useful lives noted above. For the developed technology and publisher relationship assets, as the pattern of consumption of the economic benefits of the intangible assets cannot be reliably determined, the Company amortizes these acquired intangible assets over their estimated useful lives on a straight-line basis. The Company also amortizes the trade name asset over its estimated useful life on a straight-line basis as the straight-line basis is not materially different than the pattern of consumption of economic benefit basis. Customer relationships are amortized over their useful life based on the pattern of consumption of economic benefit of the asset. Amortization commences once the asset has been placed in service.
	Amortization expense for intangible assets was $2,195, $2,403 and $1,672 for the years ended December 31, 2014, 2013 and 2012, respectively. Amortization of developed technology and publisher relationships is recorded within cost of revenue and the amortization of customer relationships and trade name is recorded within sales and marketing expense. Future estimated amortization expense as of December 31, 2014 is as follows:
	2015	$	1,583
	2016		470
	2017		107
	Total	$	2,160

Stockholders_Equity_and_StockB

Stockholders' Equity and Stock-Based Awards	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholders' Equity and Stock-Based Awards	6.    Stockholders’ Equity and Stock-Based Awards
	Preferred Stock
	The Company has authorized 5,000,000 shares of preferred stock, par value $0.01 per share, all of which is undesignated.
	Common Stock
	The Company has authorized 100,000,000 shares of common stock, par value $0.01 per share. Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of all classes of preferred stock outstanding.
	Stock Repurchase Program
	In the second quarter of 2014, the Board of Directors authorized the repurchase of up to $30,000 of its common stock through July 31, 2015. Under the authorization, the Company can repurchase shares in the open market, which may include the use of 10b5-1 trading plans, or through privately negotiated transactions. The timing and amount of repurchases will depend upon several factors, including market and business conditions. Stock repurchases may be suspended or discontinued at any time. The Company intends to fund repurchases from its cash and cash equivalents. Through December 31, 2014, 553,666 shares of common stock were repurchased at an average price of $29.55 per share for a total cost of $16,361.
	Stock-Based Awards
	Stock Plans
	The Company’s 2011 Stock Incentive Plan (the “2011 Plan”) permits the Company to make grants of incentive stock options, non-statutory stock options, restricted stock, restricted stock units, stock appreciation rights and other stock-based awards with a maximum term of seven years. These awards may be granted to the Company’s employees, officers, directors, consultants, and advisors. The Company initially reserved 4,200,000 shares of its common stock for issuance under the 2011 Plan. Additionally, per the terms of the 2011 Plan, shares of common stock previously reserved for issuance under the 2007 Stock Incentive Plan as well as shares reserved for outstanding awards under the 1999 Stock Option/Stock Issuance Plan for which the awards are cancelled, forfeited, repurchased or otherwise result in common stock not being issued will be added to the number of shares available for issuance under the 2011 Plan. Awards that were granted with a per share or per unit purchase price less than 100% of fair market value as of the date of grant (e.g., restricted stock and restricted stock unit awards) counted towards the total number of shares reserved for issuance under the 2011 Plan on a two-for-one basis. In April 2014, the Board of Directors approved an amendment and restatement of the 2011 Plan, subject to stockholder approval, which included an increase to the number of shares available for issuance under the 2011 Plan by 2,100,000 shares and a change to the number of shares that would be counted towards the total number of shares reserved for issuance for awards granted with a per share or per unit purchase price less than 100% of fair market value as of the date of grant from 2-for-1 to 1.8-for-1 for awards granted after April 1, 2014. This amendment and restatement of the 2011 Plan was approved by the stockholders in May 2014. As of December 31, 2014, 1,754,658 shares of common stock were available for issuance under the 2011 Plan.
	The Company’s 2012 Inducement Award Plan (the “2012 Inducement Plan”) provided for the grant of non-statutory stock options and restricted stock unit awards as an inducement to an individual’s entering into employment with the Company of up to an aggregate of 257,780 shares of common stock. In April 2014, the Company’s Board of Directors voted to terminate the 2012 Inducement Plan. As a result, no additional awards will be granted under this plan.
	Stock Options
	During the years ended December 31, 2014, 2013 and 2012, the Company granted 925,700, 875,975 and 1,549,932 stock options, respectively, to certain employees and directors. The vesting of most of these awards is time-based and the restrictions typically lapse over periods of three to four years.
	Through December 31, 2014, stock options were granted with exercise prices equal to the fair value of the Company’s common stock on the date of grant. The Company bases fair value of common stock on the quoted market price.
	The fair value of each stock option grant was estimated on the date of grant using the Black-Scholes option-pricing model. The Company estimates expected term based on historical exercise activity, giving consideration to the contractual term of the options and vesting schedules. Expected volatility was based on historical volatility of the Company. The risk-free interest rate was determined by reference to United States Treasury bond yields at or near the time of grant for time periods similar to the expected term of the award. The relevant data used to determine the value of the stock option grants is as follows:
		Year Ended			Year Ended			Year Ended
		December 31,			December 31,			December 31,
		2014			2013			2012
	Weighted average risk-free interest rate		1.38	%		1.07	%		0.81	%
	Expected term (in years)		4.3			4.6			4.6
	Weighted average expected volatility		49.53	%		51.14	%		53.58	%
	Expected dividends		0	%		0	%		0	%
	A summary of stock option activity is as follows:
		Number of			Weighted			Weighted			Aggregate
		Options			Average			Average			Intrinsic
					Exercise			Remaining			Value
					Price			Contractual
								Term
								(In Years)
	Balance at December 31, 2013		5,013,983		$	19.61			5.57		$	57,469
	Granted		925,700			26.01
	Exercised		(1,039,200	)		19.4
	Forfeited		(273,474	)		22.17
	Balance at December 31, 2014		4,627,009		$	20.79			4.9		$	73,638
	Vested and expected to vest at December 31, 2014		4,199,125		$	20.53			4.77		$	67,893
	Exercisable at December 31, 2014		2,767,887		$	19.67			4.42		$	47,143
	The aggregate intrinsic value was calculated based on the positive differences between the market value of the Company’s common stock on December 31, 2014 and 2013, of $36.70 and $31.07 per share, respectively, and the exercise prices of the options.
	The weighted average grant date fair value of stock options granted was $10.71, $7.14 and $9.55 per share for the years ended December 31, 2014, 2013 and 2012, respectively.
	The total intrinsic value of stock options exercised was $12,394, $6,168 and $6,530 for the years ended December 31, 2014, 2013 and 2012, respectively.
	Restricted Stock Units
	Upon vesting, the restricted stock units entitle the holder to one share of common stock for each restricted stock unit. All restricted stock units currently granted have been classified as equity instruments as their terms require settlement in shares.
	During 2014, 2013 and 2012, the Company granted 555,638, 371,415 and 718,930 restricted stock units with a weighted average grant-date fair value of $30.23, $22.63 and $16.73, respectively. The aggregate intrinsic value of restricted stock units vested in 2014, 2013 and 2012 was $7,596, $3,774 and $1,485, respectively. Of the unvested restricted units outstanding as of December 31, 2014, 534,127 are subject to time-based vesting, 362,785 are subject to performance-based vesting and 213,246 are subject to market-based vesting conditions. As of December 31, 2014, the Company estimates that 704,321 shares of restricted stock units with an intrinsic value of $25,849 and a weighted average remaining contractual term of 1.61 years will ultimately vest. A description of restricted stock units and the valuation methodologies used to value them are described below.
	Restricted stock units with time-based vesting conditions
	Time-based vesting restrictions lapse over one to four years. Restricted stock units with time-based vesting conditions are valued on the grant date using the grant date market price of the underlying shares.
	Restricted stock units with performance-based vesting conditions
	In December 2012, the Company granted 152,302 restricted stock units that vest upon the achievement of at least two years of service and a targeted revenue run rate of $500,000 (the “2012 Revenue RSUs”). The 2012 Revenue RSUs will vest upon the achievement of both (i) a performance condition and (ii) a service condition. The performance condition will be satisfied if the Company achieves a specified quarterly revenue target over a specified measurement period. To satisfy the service condition, the employee must remain employed by the Company until the later of the applicable performance determination date and the second anniversary of the date of grant. The number of 2012 Revenue RSUs that will vest upon the achievement of the performance condition and the service condition will vary based on when the performance condition is satisfied, from a maximum of 100% of the number of target shares to a threshold of 25% of the number of target shares with no vesting, absent certain circumstances in a change of control of the Company, if the targeted threshold is not achieved. If the revenue targets are not achieved by March 31, 2017, the 2012 Revenue RSUs will expire unvested.
	In December 2013 and 2014, the Company granted 102,803 and 108,140 restricted stock units, respectively, that vest upon the achievement of at least three years of service and a targeted compound annual growth rate in revenue over three years (the “2013 and 2014 Revenue RSUs”). The 2013 and 2014 Revenue RSUs will vest upon the achievement of both (i) a performance condition and (ii) a service condition. The performance condition will be satisfied if the Company achieves a specified compound annual growth rate in revenue over the specified measurement period. To satisfy the service condition, the employee must remain employed by the Company until the applicable performance determination date. The number of 2013 and 2014 Revenue RSUs that will vest upon the achievement of the performance condition and the service condition will vary based on the actual compound annual growth rate in revenue, from a maximum of 125% of the number of target shares to a threshold of 50% of the number of target shares with no vesting, absent certain circumstances in a change of control of the Company, if the targeted threshold is not achieved. If the targets are not achieved at the end of the measurement periods, the 2013 and 2014 Revenue RSUs will expire unvested.
	Restricted stock units with performance-based vesting conditions are valued on the grant date using the grant date market price of the underlying shares. At December 31, 2014, 332,785 of the 2012 Revenue RSUs and 2013 and 2014 Revenue RSUs remain outstanding. At December 31, 2014, the Company also had outstanding 30,000 restricted stock units that contain other performance-based vesting criteria.
	Restricted stock units with market-based vesting conditions
	In December 2012, 2013 and 2014, the Company granted 95,188, 52,498 and 84,598 restricted stock units, respectively, that vest upon achievement by the Company of a total shareholder return relative to a peer group target (the “TSR RSUs”) measured over a three-year period that commenced on their respective grant dates. The number of TSR RSUs that will vest upon achievement of the target will vary based on the level of achievement from a maximum of 125% of the target shares to a threshold of 50% of the target shares, with no vesting, absent certain circumstances in a change of control of the Company, if the threshold requirement is not achieved or the employee is no longer with the Company at the end of the three-year period. The TSR RSUs are valued using Monte Carlo simulation models. The number of units expected to vest, based on achievement of the TSR market condition, is factored into the grant date Monte Carlo valuations for the TSR RSUs. Compensation cost is recognized regardless of the eventual number of units that vest based on the market condition. Expected volatility was based on historical volatility of the publicly traded stock of the peer group of companies, inclusive of the Company over the last three years prior to the grant dates. The risk-free interest rate was determined by reference to United States Treasury bond yields at or near the times of grant for the three years.
	The relevant assumptions used in the Monte Carlo simulation models include (but are not limited to) the following:
		2014		2013	2012
	Monte Carlo assumptions
	Risk-free interest rate	0.96%		0.58%	0.34%
	Volatility	26.28% – 54.50%		29.00% – 60.36%	27.64% – 62.45%
	Compensation cost is recognized on a straight-line basis over the requisite service period. At December 31, 2014, 213,246 of the TSR RSUs remain outstanding.
	The table below summarizes activity relating to all restricted stock units:
		Number of Shares			Weighted
		Underlying			Average Grant
		Restricted Units			Date Fair Value
	Unvested as of December 31, 2013		902,539		$	19.4
	Restricted units granted		555,638			30.23
	Restricted units vested		(249,352	)		20.4
	Restricted units forfeited/cancelled		(98,667	)		17.25
Unvested as of December 31, 2014		1,110,158		$	24.79
Stock Purchase Plan
Under the Company’s 2007 Employee Stock Purchase Plan, as amended (the “Purchase Plan”), six-month offering periods begin on January 1 and July 1 of each year during which employees may elect to purchase shares of the Company’s common stock according to the terms of the offering. Prior to July 1, 2013, the per share purchase price for each offering was equal to 85% of the closing market price of the Company’s common stock on the last day of the offering period. Starting with the offering period that began on July 1, 2013, the per share purchase price for offerings is equal to the lesser of 85% of the closing market price of the Company’s common stock on the first day or last day of the offering period. As of December 31, 2014, 312,026 shares of common stock are available for issuance to participating employees under the Purchase Plan.
Stock-Based Compensation
The Company recognized stock-based compensation expense on all awards in cost of revenue and operating expense categories as follows:
	Years Ended
	December 31,
	2014			2013			2012
Cost of revenue	$	2,072		$	1,802		$	1,758
Research and development		3,320			3,359			3,733
Sales and marketing		4,866			3,741			3,187
General and administrative		6,392			5,829			5,596
	$	16,650		$	14,731		$	14,274
The unrecognized compensation expense associated with outstanding stock options, restricted stock and restricted stock units at December 31, 2014 was $27,974, which is expected to be recognized over a weighted-average period of 2.74 years.
For the years ended December 31, 2014, 2013 and 2012, the Company recognized income tax benefits related to stock-based compensation expense of $5,972, $5,507 and $5,354, respectively, as a component in calculating its provision for income taxes.
The Company capitalized $200, $482 and $785 of stock-based compensation expense related to the development of internal use software included in Property and equipment for the years ended December 31, 2014, 2013 and 2012, respectively.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	7.    Income Taxes
	The components of income tax expense consisted of the following:
		Years Ended
		December 31,
		2014			2013			2012
	Current income tax expense (benefit)
	Federal	$	475		$	(76	)	$	52
	State		1,396			438			474
	Total current income tax expense		1,871			362			526
	Deferred income tax expense (benefit)
	Federal		5,665			2,054			3,299
	State		(1,734	)		(1,160	)		(644	)
	Total deferred income tax expense		3,931			894			2,655
	Total income tax expense	$	5,802		$	1,256		$	3,181
	A reconciliation of the Company’s effective tax rate to the statutory federal income tax rate is as follows:
		Years Ended
		December 31,
		2014			2013			2012
	Statutory rate		35	%		35	%		35	%
	State taxes, net of federal benefit		3			5			2
	Impact of permanent differences		3			3			3
	Stock options		1			18			11
	Tax credits		(14	)		(49	)		(6	)
	Provision to return adjustments		1			4			2
	Change in the fair value of contingent consideration liability		—			—			(27	)
	Other		—			(1	)		(1	)
			29	%		15	%		19	%
	The Company had net deferred tax assets related to temporary differences and operating loss carry-forwards as follows:
		December 31,
		2014			2013
	Deferred tax assets
	Current:
	Accrued expenses	$	1,784		$	803
	Total current		1,784			803
	Noncurrent:
	Net operating loss carry-forwards		—			167
	Research and development credit carry-forwards		5,169			11,826
	Stock options		8,677			7,080
	Fixed assets		2,472			—
	Other		—			62
	Total noncurrent		16,318			19,135
	Total deferred tax assets		18,102			19,938
	Deferred tax liabilities-non-current
	Capitalized research and development		(10,439	)		(7,868	)
	Fixed assets		—			(72	)
	Intangible assets		(1,217	)		(1,621	)
	Other		(3	)		—
	Total deferred tax liabilities—non-current		(11,659	)		(9,561	)
	Net deferred tax assets	$	6,443		$	10,377
	There were no changes to the valuation allowance for the years ended December 31, 2014, 2013 or 2012.
	At December 31, 2014, the Company had federal and state net operating loss carry-forwards of approximately $8,573 and $377, respectively, which, if unused, expire at varying dates through 2034 for federal income tax purposes and at varying dates through 2026 for state income tax purposes. At December 31, 2014, all of the federal and state net operating loss carry-forwards relate to deductions for stock option compensation for which the associated tax benefit will be credited to additional paid-in capital when realized. This amount is tracked separately and not included in the Company’s deferred tax assets.
	At December 31, 2014, the Company had federal and state research and development credit carry-forwards of $9,386 and $6,782, respectively, which, if unused, will expire at varying dates through 2034 for federal income tax purposes and at varying dates through 2029 for state income tax purposes. Additionally, the Company has $1,444 of Massachusetts investment tax credits, of which $600 can be carried forward indefinitely while the remainder, which, if unused, will expire at varying dates through 2016.
	The Tax Increase Prevention Act of 2014 was enacted in December of 2014 which reinstated the federal research and development credit retroactively to January 1, 2014. As a result of the change in tax law, the Company recorded a benefit of $1,855 in the fourth quarter of 2014, the quarter in which the law was enacted for expenses incurred during 2014.
	The American Taxpayer Relief Act of 2012 (the “Act”) was enacted on January 2, 2013. The Act retroactively reinstated the federal research and development credit from January 1, 2012, through December 31, 2013. As a result of the change in the tax law, the Company recorded a benefit of $1,324 in the first quarter of 2013, the quarter in which the law was enacted for certain expenses incurred in 2012.
	The Company had not recorded any amounts for unrecognized tax benefits as of December 31, 2014, 2013 or 2012.
	The Company’s policy is to record estimated interest and penalties related to the underpayment of income taxes as a component of its income tax provision. As of December 31, 2014 and 2013, the Company had no accrued interest or tax penalties recorded. The Company’s income tax return reporting periods since December 31, 2011 are open to income tax audit examination by the federal and state tax authorities. In addition, because the Company has net operating loss carry-forwards, the Internal Revenue Service is permitted to audit earlier years and propose adjustments up to the amount of net operating loss generated in those years.
	The Company has performed an analysis of its changes in ownership under Section 382 of the Internal Revenue Code of 1986, as amended (the “Code”), and has determined that any ownership changes which have occurred do not result in a permanent limitation on usage of the Company’s federal and state net operating loss carry-forwards.

Accrued_Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
Accrued Expenses	8	Accrued Expenses
		December 31,
		2014		2013
	Payroll and payroll related	$	4,430	$	4,106
	Licensed software and maintenance		1,197		1,197
	Marketing programs		490		575
	Other accrued expenses		6,113		5,025
		$	12,230	$	10,903

401k_Savings_Plan

401(k) Savings Plan	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
401(k) Savings Plan	9	401(k) Savings Plan
	The Company has a defined contribution savings plan under Section 401(k) of the Code. This plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. Company contributions to the plan may be made at the discretion of the Board of Directors. The Company elected to make matching contributions for the plan years ending December 31, 2014, 2013 and 2012 at a rate of 100% of each employee’s contribution up to a maximum matching contribution of 3% of the employee’s compensation and at a rate of 50% of each employee’s contribution in excess of 3% up to a maximum of 5% of the employee’s compensation.
	The Company made matching contributions of an aggregate of $3,714, $2,937 and $2,457 for the years ended December 31, 2014, 2013 and 2012, respectively.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies
	Office Leases
	The Company has a lease for its headquarters space in Waltham, Massachusetts (the “Lease”) that is effective through September 2022 with one ten-year extension option. The Lease includes space the Company is currently occupying as well as space that will be made available at various points in time during the term.
	The Company leases office space for a sales and support office in Colorado under a lease agreement effective through April 2019 with three three-year extension options. The Company also leases small amounts of general office space in Florida, New York, California and the United Kingdom under lease agreements that expire at various dates through 2018.
	Lease incentives, payment escalations and rent holidays specified in the lease agreements are accrued or deferred as appropriate such that rent expense per square foot is recognized on a straight-line basis over the terms of occupancy.
	At December 31, 2014 and 2013, the Company had both prepaid rent and accrued rent balances related to its office leases. The prepaid rent balance was $51 at December 31, 2014, of which $3 was included in prepaid expenses and other current assets and $48 was included in other assets. The accrued rent balance was $4,232 at December 31, 2014, of which $577 was included in accrued expenses and $3,655 was included in other long-term liabilities. The prepaid rent balance was $634 at December 31, 2013, of which $128 was included in prepaid expenses and other current assets and $506 was included in other assets. The accrued rent balance was $2,239 at December 31, 2013, of which $351 was included in accrued expenses and $1,888 was included in other long-term liabilities.
	Total rent expense under office leases was $9,407, $8,149 and $7,102 for the years ended December 31, 2014, 2013 and 2012, respectively. Total rent expense for the year ended December 31, 2014 includes a loss on sublease of $259 and sublease income of $47.
	As of December 31, 2014, future minimum lease payments under noncancelable office leases are as follows:
	2015	$	9,374
	2016		10,037
	2017		9,981
	2018		9,604
	2019		8,492
	Thereafter		22,462
			69,950
	Less: Sublease income		678
		$	69,272
	Third-Party Hosting Agreements
	The Company has agreements with two affiliated vendors to provide specialized space and equipment and related services from which the Company hosts its software applications.
	Payment escalations and rent holidays specified in these agreements are accrued or deferred as appropriate such that rent expense per square foot is recognized on a straight-line basis over the terms of occupancy. At December 31, 2014 and 2013, the Company had both prepaid rent and accrued rent balances related to these agreements. At December 31, 2014, the Company had prepaid rent of $501, of which $295 was included in prepaid expenses and other current assets and $206 was included in other assets. The accrued rent balance was $172 of which $38 was included in accrued expense and other current liabilities and $134 was included in other long-term liabilities. At December 31, 2013, the Company had prepaid rent of $861, of which $360 was included in prepaid expenses and other current assets and $501 was included in other assets. The accrued rent balance of $173 was included in other long-term liabilities.
	Total rent expense under hosting agreements was $4,231, $4,038 and $4,073 for the years ended December 31, 2014, 2013 and 2012, respectively.
	The agreements include payment commitments that expire at various dates through mid-2017. As of December 31, 2014, future minimum payments under the agreements are as follows:
	2015	$	3,938
	2016		4,049
	2017		775
	Total	$	8,762
	Vendor Commitments
	As of December 31, 2014, the Company had issued both cancellable and non-cancellable purchase orders to various vendors and entered into contractual commitments with various vendors totaling $24,093 related to marketing programs and other non-marketing goods and services to be delivered principally during 2015.
	Letters of Credit and Restricted Cash
	As of December 31, 2014 and 2013, the Company maintained a letter of credit totaling $1,300 for the benefit of the landlord of the Lease. The landlord can draw against the letter of credit in the event of default by the Company. The Company was required to maintain a cash balance of at least $1,300 as of and December 31, 2014 and 2013 to secure the letter of credit. These amounts were classified as restricted cash in the balance sheet at December 31, 2014 and 2013.
	Indemnification Obligations
	The Company enters into standard indemnification agreements with the Company’s partners and certain other third parties in the ordinary course of business. Pursuant to these agreements, the Company indemnifies and agrees to reimburse the indemnified party for losses incurred by the indemnified party in connection with certain intellectual property infringement and other claims by any third party with respect to the Company’s business and technology. Based on historical information and information known as of December 31, 2014, the Company does not expect it will incur any significant liabilities under these indemnification agreements.
	Legal Matters
	In September 2012, RPost Holdings, Inc., RPost Communications Limited and RMail Limited (collectively, “RPost”) filed a complaint in the United States District Court for the Eastern District of Texas that named the Company as a defendant in a lawsuit. The complaint alleges that certain elements of the Company’s email marketing technology infringe five patents held by RPost. RPost seeks an award for damages in an unspecified amount and injunctive relief. In February 2013, RPost amended its complaint to name five of the Company’s marketing partners as defendants. Under the Company’s contractual agreements with these marketing partners, the Company is obligated to indemnify them for claims related to patent infringement. The Company filed a motion to sever and stay the claims against its partners and multiple motions to dismiss the claims against the Company. In January 2014, the case was stayed pending the resolution of certain state court and bankruptcy court actions involving RPost, to which the Company is not a party. The stay was extended by agreement of the parties in December 2014. This litigation is in its very early stages. As a result, neither the ultimate outcome of this litigation nor an estimate of a probable loss or any reasonably possible losses can be assessed at this time. Nevertheless, the Company believes that it has meritorious defenses to any claim of infringement and intends to defend itself vigorously.
	In March 2013, CreateAds LLC (“CreateAds”) filed a complaint in the United States District Court for the District of Delaware that named the Company as a defendant in a lawsuit. The complaint, which was served on the Company on March 8, 2013, alleges that certain elements of the Company’s email marketing technology infringe a patent held by CreateAds. CreateAds seeks an award for damages in an unspecified amount and injunctive relief. In February 2014, the case was stayed pending a decision by the United States Supreme Court in the appeal of a patent case with issues very similar to the ones pending in the Company’s motion to dismiss. Following the Supreme Court’s decision in June 2014, the Company filed a motion for summary judgment seeking to invalidate the patent for lack of patent-eligible subject matter. By agreement of the parties, the case was dismissed with prejudice as to the claims raised by CreateAds in February 2015.
	The Company is from time to time subject to various other legal proceedings and claims, either asserted or unasserted, which arise in the ordinary course of its business. While the outcome of these other claims cannot be predicted with certainty, management does not believe that the outcome of any of these other legal matters will have a material adverse effect on the Company’s results of operations or financial condition.

Quarterly_Information_Unaudite

Quarterly Information (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Information (Unaudited)	11	Quarterly Information (Unaudited)
		Three Months Ended
		Dec. 31,		Sept. 30,		June 30,		March 31,		Dec. 31,		Sept. 30,		June 30,			March 31,
		2014		2014		2014		2014		2013		2013		2013			2013
	Statements of Operations Data:
	Revenue	$	88,054	$	83,494	$	81,256	$	78,874	$	74,931	$	72,039	$	70,208		$	68,205
	Gross profit		64,041		60,271		59,156		57,147		54,279		51,561		49,630			48,297
	Income (loss) from operations		7,558		8,083		3,007		1,153		5,498		5,508		(98	)		(2,613	)
	Net income (loss)		6,248		5,198		2,021		848		4,516		3,320		32			(654	)
	Basic net income (loss) per share	$	0.2	$	0.16	$	0.06	$	0.03	$	0.15	$	0.11	$	0		$	(0.02	)
	Diluted net income (loss) per share	$	0.19	$	0.16	$	0.06	$	0.03	$	0.14	$	0.11	$	0		$	(0.02	)

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation
	The accompanying consolidated financial statements include those of the Company and its subsidiaries, after elimination of all intercompany accounts and transactions. The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”).
Use of Estimates	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. On an ongoing basis, management evaluates these estimates, judgments and assumptions, including those related to revenue recognition, stock-based compensation, goodwill and acquired intangible assets, capitalization of software and website development costs and income taxes. The Company bases these estimates on historical and anticipated results and trends and on various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenue and expenses that are not readily apparent from other sources. Actual results could differ from these estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. A fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last is considered unobservable, are used to measure fair value:
		•		Level 1 — Quoted prices in active markets for identical assets or liabilities.
		•		Level 2 — Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
		•		Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	During the years ended December 31, 2014, 2013 and 2012, there were no transfers between Level 1, Level 2 and Level 3.
	The following tables present the Company’s fair value hierarchy for its assets which are measured at fair value on a recurring basis as of December 31, 2014 and 2013:
			Fair Value Measurements at December 31, 2014 Using
			Level 1			Level 2		Level 3			Total
	Financial Assets:
	Money Market Instruments		$	5,885		$	—	$	—		$	5,885
	United States Treasury Notes			20,006			—		—			20,006
	Corporate and Agency Bonds			—			37,316		—			37,316
	Commercial Paper			—			999		—			999
	Total		$	25,891		$	38,315	$	—		$	64,206
			Fair Value Measurements at December 31, 2013 Using
			Level 1			Level 2		Level 3			Total
	Financial Assets:
	Money Market Instruments		$	23,444		$	—	$	—		$	23,444
	United States Treasury Notes			27,035			—		—			27,035
	Corporate and Agency Bonds			—			12,688		—			12,688
	Commercial Paper			—			1,000		—			1,000
	Total		$	50,479		$	13,688	$	—		$	64,167
	The Company had a contingent consideration liability associated with the acquisition of SinglePlatform, Corp. (“SinglePlatform”) in June 2012, which had been assessed at $0 as of December 31, 2013. The final measurement period for achievement of the goals related to the contingent consideration ended on June 30, 2014 and resulted in no payout of consideration. Prior to June 30, 2014, contingent consideration was measured at fair value and was based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy. The valuation of the contingent consideration liability used assumptions and estimates to forecast a range of outcomes for the contingent consideration. The Company assessed these assumptions and estimates on a quarterly basis as additional data impacting the assumptions was obtained. Changes in the fair value of the contingent consideration liability related to updated assumptions and estimates were recognized within the consolidated statements of operations. There were no changes to the fair value of the contingent consideration liability for either of the years ended December 31, 2014 or 2013. The change in the fair value of the contingent consideration liability from the date of the SinglePlatform acquisition through December 31, 2012 resulted from reductions to the SinglePlatform revenue forecast scenarios. The revenue forecast scenarios were decreased due to SinglePlatform’s actual operating results and reduced productivity of its sales organization during 2012.
	Changes in the fair value of the Level 3 contingent consideration liability associated with the acquisition were as follows:
			Contingent Consideration
			Liability
	Acquisition of SinglePlatform in June 2012		$	12,152
	Change in fair value of contingent consideration liability, included in acquisition costs and other related charges in 2012			(12,152	)
	Balance at December 31, 2012, 2013 and 2014		$	—
Fair Value Option for Financial Assets and Financial Liabilities	Fair Value Option for Financial Assets and Financial Liabilities
	Authoritative guidance allows companies to choose to measure many financial instruments and certain other items at fair value. The Company has elected not to apply the fair value option to any of its financial assets or liabilities.
Cash and Cash Equivalents	Cash and Cash Equivalents
	The Company considers all highly liquid investments with original maturities of three months or less at the time of acquisition to be cash equivalents. The Company also considers receivables related to customer credit card purchases of $1,502 and $2,901 at December 31, 2014 and 2013, respectively, to be equivalent to cash. Cash equivalents are stated at fair value.
Marketable Securities	Marketable Securities
	The Company’s marketable securities are classified as available-for-sale and are carried at fair value with the unrealized gains and losses reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Realized gains and losses and declines in value judged to be other than temporary are included as a component of other income (expense), net based on the specific identification method. Fair value is determined based on quoted market prices. At December 31, 2014, marketable securities by security type consisted of:
			Amortized			Gross		Gross			Estimated
			Cost			Unrealized		Unrealized			Fair
						Gains		Losses			Value
	United States Treasury Notes		$	20,000		$	6	$	—		$	20,006
	Corporate and Agency Bonds			37,330			2		(16	)		37,316
	Commercial Paper			999			—		—			999
	Total		$	58,329		$	8	$	(16	)	$	58,321
	At December 31, 2014, marketable securities consisted of investments that mature within one year with the exception of government treasuries and corporate and agency bonds with a fair value of $6,644, which have maturities within two years.
	At December 31, 2013, marketable securities by security type consisted of:
			Amortized			Gross		Gross			Estimated
			Cost			Unrealized		Unrealized			Fair
						Gains		Losses			Value
	United States Treasury Notes		$	27,022		$	13	$	—		$	27,035
	Corporate and Agency Bonds			12,684			4		—			12,688
	Commercial Paper			1,000			—		—			1,000
	Total		$	40,706		$	17	$	—		$	40,723
Accounts Receivable	Accounts Receivable
	Management reviews accounts receivable on a periodic basis to determine if any receivables will potentially be uncollectible. The Company reserves for receivables that are determined to be uncollectible, if any, in its allowance for doubtful accounts. After the Company has exhausted all collection efforts, the outstanding receivable is written off against the allowance.
Concentration of Credit Risk and Significant Products and Customers	Concentration of Credit Risk and Significant Products and Customers
	Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. At December 31, 2014 and 2013, the Company had substantially all cash balances at certain financial institutions without or in excess of federally insured limits, however, the Company maintains its cash balances and custody of its marketable securities with accredited financial institutions. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.
	For the years ended December 31, 2014, 2013 and 2012, revenue from the Company’s email marketing product alone as a percentage of total revenue was approximately 80%, 84% and 85%, respectively. No customer accounted for more than 10% of total revenue during these years.
Goodwill and Acquired Intangible Assets	Goodwill and Acquired Intangible Assets
	The Company records goodwill when consideration paid in a business acquisition exceeds the fair value of the net tangible assets and the identified intangible assets acquired. Goodwill is not amortized, but rather is tested for impairment annually or more frequently if facts and circumstances warrant a review. The Company performs its annual assessment for impairment of goodwill on November 30th of each year and has determined that there is a single reporting unit for the purpose of conducting this annual goodwill impairment assessment. For purposes of assessing potential impairment, the Company annually estimates the fair value of the reporting unit (based on the Company’s market capitalization) and compares this amount to the carrying value of the reporting unit (as reflected by the Company’s total stockholders’ equity). If the Company determines that the carrying value of the reporting unit exceeds its fair value, an impairment charge would be required.
	Intangible assets are recorded at their estimated fair values at the date of acquisition. The Company amortizes acquired intangible assets over their estimated useful lives based on the pattern of consumption of the economic benefits or, if that pattern cannot be readily determined, on a straight-line basis.
Property and Equipment	Property and Equipment
	Property and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful life of the assets or, where applicable and if shorter, over the lease term. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are eliminated from the accounts and any resulting gain or loss is credited or charged to the statement of operations. Repairs and maintenance costs are expensed as incurred.
	Estimated useful lives of assets are as follows:
	Computer equipment		3 years
	Software		3 years
	Furniture and fixtures		5 years
	Leasehold improvements		Shorter of life of lease or
			estimated useful life
Long-Lived Assets	Long-Lived Assets
	The Company reviews the carrying values of its long-lived assets for possible impairment when events or changes in circumstance indicate that the related carrying amount may not be recoverable. Undiscounted cash flows are compared to the carrying value and when required, impairment losses on assets to be held and used are recognized based on the excess of the asset’s carrying amount over the fair value of the asset. Long-lived assets to be disposed of are reported at the lower of carrying amount or fair value less cost to sell.
Revenue Recognition	Revenue Recognition
	The Company provides access to its products primarily through subscription arrangements whereby the customer is charged a fee for access for a defined term. Subscription arrangements include access to use the Company’s software via the Internet and support services, such as telephone, email and chat support. When there is evidence of an arrangement, the fee is fixed or determinable and collectability is deemed reasonably assured, the Company recognizes revenue on a daily basis over the subscription period as the services are delivered. Delivery is considered to have commenced at the time the customer has paid for the products and has access to the account via a log-in and password. The Company also offers ancillary services to its customers related to its subscription-based products such as custom services and training. When sold together, revenue from custom services, training and subscription products are accounted for separately based on vendor-specific objective evidence of fair value of each of the services as those services have value on a standalone basis and do not involve a significant degree of risk or unique acceptance criteria. Revenue from custom services and training is recognized as the services are performed. Revenue from transaction-based products and services is recognized based on the transactional fee charged when there is evidence of an arrangement, the fee is fixed or determinable, collectability is deemed reasonably assured and the transaction has occurred.
Deferred Revenue	Deferred Revenue
	Deferred revenue consists of payments received in advance of delivery of the Company’s on-demand products described above and is recognized as the revenue recognition criteria are met. The Company’s customers generally pay for services in advance on a monthly, semiannual or annual basis.
Software and Website Development Costs	Software and Website Development Costs
	Research and development costs are expensed as incurred and primarily include salaries, fees to consultants, and other related costs. Relative to development costs of its on-demand products and website, the Company capitalizes certain direct costs to develop functionality as well as certain upgrades and enhancements that are probable to result in additional functionality. The costs incurred in the preliminary stages of development are expensed as incurred. Once an application has reached the development stage, internal and external costs, if direct and incremental, are capitalized as part of property and equipment until the software is substantially complete and ready for its intended use. Capitalized software is amortized over a three-year period in the expense category to which the software relates.
Foreign Currency Translation	Foreign Currency Translation
	The functional currency of the Company’s operations in the United Kingdom is deemed to be the British pound. Accordingly, the assets and liabilities of the Company’s United Kingdom subsidiary are translated into United States dollars using the period-end exchange rate, and income and expense items are translated using the average exchange rate during the period. Cumulative translation adjustments are reflected as a separate component of stockholders’ equity. Foreign currency transaction gains and losses are charged to Other income (expense), net and were not material to the Company’s operations.
Comprehensive Income	Comprehensive Income
	Comprehensive income includes net income, as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The Company’s only elements of other comprehensive income (loss) are unrealized gains and losses on available-for-sale securities and translation adjustments.
Segment Data	Segment Data
	The Company manages its operations as a single segment for purposes of assessing performance and making operating decisions. Revenue is generated predominately in the United States and all significant assets are held in the United States.
Net Income Per Share	Net Income Per Share
	Basic net income per share is computed by dividing net income by the weighted average number of unrestricted common shares outstanding during the period.
	Diluted net income per share is computed by dividing net income by the sum of the weighted average number of unrestricted common shares outstanding during the period and the weighted average number of potential common shares from the assumed exercise of stock options and the vesting of shares of restricted common stock and restricted stock units using the “treasury stock” method when the effect is not anti-dilutive.
	The following is a summary of the shares used in computing diluted net income per share:
			Years ended December 31,
			2014			2013		2012
			(in thousands)
	Weighted average shares used in calculating basic net income per share			31,619			30,730		30,386
	Stock options			1,100			524		581
	Warrants			—			1		1
	Unvested restricted stock and restricted stock units			117			101		35
	Shares used in computing diluted net income per share			32,836			31,356		31,003
	The Company excluded the following common stock equivalents from the computation of diluted net income per share because they had an anti-dilutive impact because the proceeds under the treasury stock method were in excess of the average fair market value for the period:
			Years ended December 31,
			2014			2013		2012
			(in thousands)
	Options to purchase common stock			1,278			3,586		3,342
	Unvested restricted stock and restricted stock units			200			176		110
	Total options exercisable into common stock, restricted stock units issuable in common stock and restricted stock			1,478			3,762		3,452
Advertising Expense	Advertising Expense
	The Company expenses advertising as incurred. Advertising expense was $42,234, $39,796 and $35,350 during the years ended December 31, 2014, 2013 and 2012, respectively.
Accounting for Stock-Based Compensation	Accounting for Stock-Based Compensation
	The Company values all stock-based compensation, including grants of stock options, restricted stock and restricted stock units, at fair value on the date of grant, and expenses the fair value over the applicable service period. The straight-line method is applied to all grants with service and market conditions, while the graded vesting method is applied to all grants with both service and performance conditions.
Income Taxes	Income Taxes
	Income taxes are provided for tax effects of transactions reported in the financial statements and consist of income taxes currently due plus deferred income taxes related to timing differences between the basis of certain assets and liabilities for financial statement and income tax reporting purposes. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. A valuation allowance is provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.
	The Company accounts for uncertainty in income taxes recognized in the financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination. If the tax position is deemed “more-likely-than-not” to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board (“FASB”) issued new guidance, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. This guidance will replace most existing revenue recognition guidance in GAAP when it becomes effective. The guidance also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The new guidance is effective for the Company commencing January 1, 2017. Early application is not permitted. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that this guidance will have on its consolidated financial statements.
	In August 2014, FASB issued new guidance, Presentation of Financial Statements—Going Concern. The new guidance addresses management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. Management’s evaluation should be based on relevant conditions and events that are known and reasonably knowable at the date that the financial statements are issued. The standard will be effective for the first interim period within annual reporting periods beginning after December 15, 2016. Early adoption is permitted. The Company is evaluating the effect that this guidance will have on its consolidated financial statements.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Fair Value Hierarchy for Cash Equivalents and Marketable Securities Measured at Fair Value on Recurring Basis	The following tables present the Company’s fair value hierarchy for its assets, which are measured at fair value on a recurring basis as of December 31, 2014 and 2013:
		Fair Value Measurements at December 31, 2014 Using
		Level 1			Level 2		Level 3			Total
	Financial Assets:
	Money Market Instruments	$	5,885		$	—	$	—		$	5,885
	United States Treasury Notes		20,006			—		—			20,006
	Corporate and Agency Bonds		—			37,316		—			37,316
	Commercial Paper		—			999		—			999
	Total	$	25,891		$	38,315	$	—		$	64,206
		Fair Value Measurements at December 31, 2013 Using
		Level 1			Level 2		Level 3			Total
	Financial Assets:
	Money Market Instruments	$	23,444		$	—	$	—		$	23,444
	United States Treasury Notes		27,035			—		—			27,035
	Corporate and Agency Bonds		—			12,688		—			12,688
	Commercial Paper		—			1,000		—			1,000
	Total	$	50,479		$	13,688	$	—		$	64,167
Changes in Fair Value of Level 3 Contingent Consideration Liability	Changes in the fair value of the Level 3 contingent consideration liability associated with the SinglePlatform acquisition were as follows:
		Contingent Consideration
		Liability
	Acquisition of SinglePlatform in June 2012	$	12,152
	Change in fair value of contingent consideration liability, included in acquisition costs and other related charges in 2012		(12,152	)
	Balance at December 31, 2012, 2013 and 2014	$	—
Summary of Marketable Securities by Security Type	At December 31, 2014, marketable securities by security type consisted of:
		Amortized			Gross		Gross			Estimated
		Cost			Unrealized		Unrealized			Fair
					Gains		Losses			Value
	United States Treasury Notes	$	20,000		$	6	$	—		$	20,006
	Corporate and Agency Bonds		37,330			2		(16	)		37,316
	Commercial Paper		999			—		—			999
	Total	$	58,329		$	8	$	(16	)	$	58,321
	At December 31, 2014, marketable securities consisted of investments that mature within one year with the exception of government treasuries and corporate and agency bonds with a fair value of $6,644, which have maturities within two years.
	At December 31, 2013, marketable securities by security type consisted of:
		Amortized			Gross		Gross			Estimated
		Cost			Unrealized		Unrealized			Fair
					Gains		Losses			Value
	United States Treasury Notes	$	27,022		$	13	$	—		$	27,035
	Corporate and Agency Bonds		12,684			4		—			12,688
	Commercial Paper		1,000			—		—			1,000
	Total	$	40,706		$	17	$	—		$	40,723
Estimated Useful Lives of Assets	Estimated useful lives of assets are as follows:
	Computer equipment	3 years
	Software	3 years
	Furniture and fixtures	5 years
	Leasehold improvements	Shorter of life of lease or
		estimated useful life
Summary of Shares Used in Computing Diluted Net Income Per Share	The following is a summary of the shares used in computing diluted net income per share:
		Years ended December 31,
		2014			2013		2012
		(in thousands)
	Weighted average shares used in calculating basic net income per share		31,619			30,730		30,386
	Stock options		1,100			524		581
	Warrants		—			1		1
	Unvested restricted stock and restricted stock units		117			101		35
	Shares used in computing diluted net income per share		32,836			31,356		31,003
Common Stock Equivalents Excluded from Computation of Diluted Net Income Per Share	The Company excluded the following common stock equivalents from the computation of diluted net income per share because they had an anti-dilutive impact because the proceeds under the treasury stock method were in excess of the average fair market value for the period:
		Years ended December 31,
		2014			2013		2012
		(in thousands)
	Options to purchase common stock		1,278			3,586		3,342
	Unvested restricted stock and restricted stock units		200			176		110
	Total options exercisable into common stock, restricted stock units issuable in common stock and restricted stock		1,478			3,762		3,452

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consisted of the following:
		December 31,
		2014		2013
	Computer equipment	$	51,439	$	52,059
	Software		50,590		43,377
	Furniture and fixtures		8,634		8,599
	Leasehold improvements		16,340		11,657
	Total property and equipment		127,003		115,692
	Less: Accumulated depreciation and amortization		83,264		76,454
	Property and equipment, net	$	43,739	$	39,238

Acquisitions_Tables

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2014
CardStar [Member]
Allocation of Purchase Price	The Company allocated the purchase price as follows:
	Developed technology	$	624
	Net deferred tax assets		553
	Goodwill		4,573
	Total assets acquired	$	5,750
SinglePlatform [Member]
Allocation of Purchase Price	The following table summarizes the purchase price for SinglePlatform and the allocation of the purchase price:
	Purchase consideration:
	Total cash paid, net of cash acquired	$	62,546
	Cash acquired		311
	Fair value of contingent consideration		12,152
	Total purchase price consideration	$	75,009
	Assets acquired and liabilities assumed:
	Cash	$	311
	Accounts receivable		48
	Prepaid expenses and other current assets		60
	Property and equipment		14
	Identifiable intangible assets		4,760
	Other assets		91
	Net deferred tax assets		72
	Goodwill		71,997
	Total assets acquired		77,353
	Accounts payable, accrued expenses and other current liabilities		(1,734	)
	Deferred revenue		(610	)
	Total liabilities assumed		(2,344	)
	Total allocation of purchase price consideration	$	75,009
Estimated Fair Values and Useful Lives of Identifiable Intangible Assets Acquired	The following table presents the estimated fair values and useful lives of identifiable intangible assets acquired:
		Amount			Weighted Average Useful
					Life
					(in years)
	Developed technology	$	850			3
	Customer relationships		2,630			3.75
	Publisher relationships		710			5
	Trade name		570			5
	Total identifiable intangible assets	$	4,760			3.95
Pro Forma Results of Historical Consolidated Statements of Operations	The following table presents the pro forma results of the historical consolidated statements of operations of the Company and SinglePlatform for the year ended December 31, 2012, giving effect to the merger as if it occurred on January 1, 2011:
		Year ended
		December 31, 2012
	Pro forma revenue	$	252,618
	Pro forma net income	$	11,173

Goodwill_and_Acquired_Intangib1

Goodwill and Acquired Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible assets consist of the following:
		Estimated		December 31, 2014						December 31, 2013
		Useful Life		Gross		Accumulated		Net Carrying		Gross		Accumulated		Net Carrying
				Carrying		Amortization		Amount		Carrying		Amortization		Amount
				Amount						Amount
	Developed technology		3 years	$	4,357	$	3,465	$	892	$	4,357	$	2,336	$	2,021
	Customer relationships		3.75 years		3,315		2,666		649		3,315		1,855		1,460
	Publisher relationships		5 years		710		367		343		710		225		485
	Trade name		5 years		570		294		276		570		181		389
				$	8,952	$	6,792	$	2,160	$	8,952	$	4,597	$	4,355
Future Estimated Amortization Expense for Intangible Assets	Future estimated amortization expense as of December 31, 2014 is as follows:
	2015	$	1,583
	2016		470
	2017		107
	Total	$	2,160

Stockholders_Equity_and_StockB1

Stockholders' Equity and Stock-Based Awards (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Value of Stock Option Grants	The relevant data used to determine the value of the stock option grants is as follows:
		Year Ended			Year Ended			Year Ended
		December 31,			December 31,			December 31,
		2014			2013			2012
	Weighted average risk-free interest rate		1.38	%		1.07	%		0.81	%
	Expected term (in years)		4.3			4.6			4.6
	Weighted average expected volatility		49.53	%		51.14	%		53.58	%
	Expected dividends		0	%		0	%		0	%
Summary of Stock Option Activity	A summary of stock option activity is as follows:
		Number of			Weighted			Weighted			Aggregate
		Options			Average			Average			Intrinsic
					Exercise			Remaining			Value
					Price			Contractual
								Term
								(In Years)
	Balance at December 31, 2013		5,013,983		$	19.61			5.57		$	57,469
	Granted		925,700			26.01
	Exercised		(1,039,200	)		19.4
	Forfeited		(273,474	)		22.17
	Balance at December 31, 2014		4,627,009		$	20.79			4.9		$	73,638
	Vested and expected to vest at December 31, 2014		4,199,125		$	20.53			4.77		$	67,893
	Exercisable at December 31, 2014		2,767,887		$	19.67			4.42		$	47,143
Monte Carlo Assumptions	The relevant assumptions used in the Monte Carlo simulation models include (but are not limited to) the following:
		2014		2013	2012
	Monte Carlo assumptions
	Risk-free interest rate	0.96%		0.58%	0.34%
	Volatility	26.28% – 54.50%		29.00% – 60.36%	27.64% – 62.45%
Restricted Stock and Restricted Stock Units Activity	The table below summarizes activity relating to all restricted stock units:
		Number of Shares			Weighted
		Underlying			Average Grant
		Restricted Units			Date Fair Value
	Unvested as of December 31, 2013		902,539		$	19.4
	Restricted units granted		555,638			30.23
	Restricted units vested		(249,352	)		20.4
	Restricted units forfeited/cancelled		(98,667	)		17.25
	Unvested as of December 31, 2014		1,110,158		$	24.79
Recognized Stock-Based Compensation Expense	The Company recognized stock-based compensation expense on all awards in cost of revenue and operating expense categories as follows:
		Years Ended
		December 31,
		2014			2013			2012
	Cost of revenue	$	2,072		$	1,802		$	1,758
	Research and development		3,320			3,359			3,733
	Sales and marketing		4,866			3,741			3,187
	General and administrative		6,392			5,829			5,596
		$	16,650		$	14,731		$	14,274

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The components of income tax expense consisted of the following:
		Years Ended
		December 31,
		2014			2013			2012
	Current income tax expense (benefit)
	Federal	$	475		$	(76	)	$	52
	State		1,396			438			474
	Total current income tax expense		1,871			362			526
	Deferred income tax expense (benefit)
	Federal		5,665			2,054			3,299
	State		(1,734	)		(1,160	)		(644	)
	Total deferred income tax expense		3,931			894			2,655
	Total income tax expense	$	5,802		$	1,256		$	3,181
Reconciliation of Company's Effective Tax Rate to Statutory Federal Income Tax Rate	A reconciliation of the Company’s effective tax rate to the statutory federal income tax rate is as follows:
		Years Ended
		December 31,
		2014			2013			2012
	Statutory rate		35	%		35	%		35	%
	State taxes, net of federal benefit		3			5			2
	Impact of permanent differences		3			3			3
	Stock options		1			18			11
	Tax credits		(14	)		(49	)		(6	)
	Provision to return adjustments		1			4			2
	Change in the fair value of contingent consideration liability		—			—			(27	)
	Other		—			(1	)		(1	)
			29	%		15	%		19	%
Net Deferred Tax Assets Related to Temporary Differences and Operating Loss Carry-Forwards	The Company had net deferred tax assets related to temporary differences and operating loss carry-forwards as follows:
		December 31,
		2014			2013
	Deferred tax assets
	Current:
	Accrued expenses	$	1,784		$	803
	Total current		1,784			803
	Noncurrent:
	Net operating loss carry-forwards		—			167
	Research and development credit carry-forwards		5,169			11,826
	Stock options		8,677			7,080
	Fixed assets		2,472			—
	Other		—			62
	Total noncurrent		16,318			19,135
	Total deferred tax assets		18,102			19,938
	Deferred tax liabilities-non-current
	Capitalized research and development		(10,439	)		(7,868	)
	Fixed assets		—			(72	)
	Intangible assets		(1,217	)		(1,621	)
	Other		(3	)		—
	Total deferred tax liabilities—non-current		(11,659	)		(9,561	)
	Net deferred tax assets	$	6,443		$	10,377

Accrued_Expenses_Tables

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
Components of Accrued Expenses
		December 31,
		2014		2013
	Payroll and payroll related	$	4,430	$	4,106
	Licensed software and maintenance		1,197		1,197
	Marketing programs		490		575
	Other accrued expenses		6,113		5,025
		$	12,230	$	10,903

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Office Leases [Member]
Future Minimum Lease Payments under Leases and Agreements	As of December 31, 2014, future minimum lease payments under noncancelable office leases are as follows:
	2015	$	9,374
	2016		10,037
	2017		9,981
	2018		9,604
	2019		8,492
	Thereafter		22,462
			69,950
	Less: Sublease income		678
		$	69,272
Third-Party Hosting Agreements [Member]
Future Minimum Lease Payments under Leases and Agreements	As of December 31, 2014, future minimum payments under the agreements are as follows:
	2015	$	3,938
	2016		4,049
	2017		775
	Total	$	8,762

Quarterly_Information_Unaudite1

Quarterly Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Information
		Three Months Ended
		Dec. 31,		Sept. 30,		June 30,		March 31,		Dec. 31,		Sept. 30,		June 30,			March 31,
		2014		2014		2014		2014		2013		2013		2013			2013
	Statements of Operations Data:
	Revenue	$	88,054	$	83,494	$	81,256	$	78,874	$	74,931	$	72,039	$	70,208		$	68,205
	Gross profit		64,041		60,271		59,156		57,147		54,279		51,561		49,630			48,297
	Income (loss) from operations		7,558		8,083		3,007		1,153		5,498		5,508		(98	)		(2,613	)
	Net income (loss)		6,248		5,198		2,021		848		4,516		3,320		32			(654	)
	Basic net income (loss) per share	$	0.2	$	0.16	$	0.06	$	0.03	$	0.15	$	0.11	$	0		$	(0.02	)
	Diluted net income (loss) per share	$	0.19	$	0.16	$	0.06	$	0.03	$	0.14	$	0.11	$	0		$	(0.02	)

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 12, 2012
Summary Of Significant Accounting Policies [Line Items]
Transfers in and out of Level 1, Level 2 and Level 3	$0	$0	$0
Cash and cash equivalents and short term investments maturity period	3 months
Credit card receivables	1,502,000	2,901,000
Advertising expense	42,234,000	39,796,000	35,350,000
Minimum percentage of probability of realizing the benefit upon ultimate settlement	50.00%
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Maturity period for marketable securities classified as available-for-sale	1 year
Sales [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of customers accounted for more than specified percentage of revenue	0	0	0
Sales [Member] | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenue received	80.00%	84.00%	85.00%
Sales [Member] | Minimum [Member] | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenue received	10.00%	10.00%	10.00%
SinglePlatform [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of the contingent consideration liability	0	0	0	12,152,000
Corporate and Agency Bonds [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of agency bonds and treasury notes classified as available-for-sale securities	$6,644,000
Corporate and Agency Bonds [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Maturity period for marketable securities classified as available-for-sale	2 years
Software and Website Development Costs [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated economic life of the developed technology related to acquisition	3 years

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Fair Value Hierarchy for Cash Equivalents and Marketable Securities Measured at Fair Value on Recurring Basis (Detail) (Recurring [Member], USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial Assets:
Total	$64,206	$64,167
Money Market Instruments [Member]
Financial Assets:
Cash and cash equivalents fair value disclosure	5,885	23,444
United States Treasury Notes [Member]
Financial Assets:
Available for sale securities fair value disclosure	20,006	27,035
Corporate and Agency Bonds [Member]
Financial Assets:
Available for sale securities fair value disclosure	37,316	12,688
Commercial Paper [Member]
Financial Assets:
Available for sale securities fair value disclosure	999	1,000
Level 2 [Member]
Financial Assets:
Total	38,315	13,688
Level 2 [Member] | Corporate and Agency Bonds [Member]
Financial Assets:
Available for sale securities fair value disclosure	37,316	12,688
Level 2 [Member] | Commercial Paper [Member]
Financial Assets:
Available for sale securities fair value disclosure	999	1,000
Level 1 [Member]
Financial Assets:
Total	25,891	50,479
Level 1 [Member] | Money Market Instruments [Member]
Financial Assets:
Cash and cash equivalents fair value disclosure	5,885	23,444
Level 1 [Member] | United States Treasury Notes [Member]
Financial Assets:
Available for sale securities fair value disclosure	$20,006	$27,035

Summary_of_Significant_Account5

Summary of Significant Accounting Policies - Changes in Fair Value of Level 3 Contingent Consideration Liability (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Jun. 30, 2012
Business Acquisition, Contingent Consideration [Line Items]
Change in fair value of contingent consideration liability, included in acquisition costs and other related charges	$12,152
Level 3 [Member]
Business Acquisition, Contingent Consideration [Line Items]
Acquisition of SinglePlatform		12,152
Change in fair value of contingent consideration liability, included in acquisition costs and other related charges	($12,152)

Summary_of_Significant_Account6

Summary of Significant Accounting Policies - Summary of Marketable Securities by Security Type (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$58,329	$40,706
Gross Unrealized Gains	8	17
Gross Unrealized Losses	-16
Estimated Fair Value	58,321	40,723
U.S. Treasury Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,000	27,022
Gross Unrealized Gains	6	13
Estimated Fair Value	20,006	27,035
Corporate and Agency Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	37,330	12,684
Gross Unrealized Gains	2	4
Gross Unrealized Losses	-16
Estimated Fair Value	37,316	12,688
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	999	1,000
Estimated Fair Value	$999	$1,000

Summary_of_Significant_Account7

Summary of Significant Accounting Policies - Estimated Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2014
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years
Software [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	3 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives of Leasehold improvements	Shorter of life of lease or estimated useful life

Summary_of_Significant_Account8

Summary of Significant Accounting Policies - Summary of Shares used in Computing Diluted Net Income Per Share (Detail)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average shares used in calculating basic net income per share	31,619	30,730	30,386
Shares used in computing diluted net income per share	32,836	31,356	31,003
Stock Options [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock options and unvested restricted stock	1,100	524	581
Warrants [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Warrants		1	1
Unvested Restricted Stock and Restricted Stock Units [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stock options and unvested restricted stock	117	101	35

Summary_of_Significant_Account9

Summary of Significant Accounting Policies - Common Stock Equivalents Excluded from Computation of Diluted Net Income Per Share (Detail)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total options exercisable into common stock, restricted stock units issuable in common stock and restricted stock	1,478	3,762	3,452
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total options exercisable into common stock, restricted stock units issuable in common stock and restricted stock	1,278	3,586	3,342
Unvested Restricted Stock and Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total options exercisable into common stock, restricted stock units issuable in common stock and restricted stock	200	176	110

Property_and_Equipment_Summary

Property and Equipment - Summary of Property and Equipment (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Abstract]
Computer equipment	$51,439	$52,059
Software	50,590	43,377
Furniture and fixtures	8,634	8,599
Leasehold improvements	16,340	11,657
Total property and equipment	127,003	115,692
Less: Accumulated depreciation and amortization	83,264	76,454
Property and equipment, net	$43,739	$39,238

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$21,969	$19,788	$17,331
Disposed of and sold assets, gross	15,159
Capitalized costs associated with the development of internal use software	7,892	7,411	6,673
Amortization expense	6,689	4,575	3,383
Capitalized software costs, net	$15,299	$14,096

Acquisitions_Additional_Inform

Acquisitions - Additional Information (Detail) (USD $)	12 Months Ended			0 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 13, 2012	Jun. 12, 2012
Business Acquisition [Line Items]
Intervals period to be measured revenue targets	6 months
Contingent consideration adjustment			($12,152)
Transactions costs related to acquisitions	0	0	797
Developed Technology [Member]
Business Acquisition [Line Items]
Estimated economic life of the developed technology related to acquisition	3 years
CardStar [Member]
Business Acquisition [Line Items]
Cash purchase price				5,750
CardStar [Member] | Developed Technology [Member]
Business Acquisition [Line Items]
Estimated economic life of the developed technology related to acquisition	3 years
SinglePlatform [Member]
Business Acquisition [Line Items]
Cash purchase price					62,857
Total purchase price included in acquisition of Single Platform					75,009
Fair value of contingent consideration payable	0	0	0		12,152
The estimated undiscounted range of outcomes for the contingent consideration, low					0
The estimated undiscounted range of outcomes for the contingent consideration, high					21,095
Contingent consideration adjustment			12,152
SinglePlatform [Member] | Maximum [Member]
Business Acquisition [Line Items]
Amount payable upon achievement of certain revenue targets					$30,000

Acquisitions_Allocation_of_Pur

Acquisitions - Allocation of Purchase Price (Detail) (USD $)	0 Months Ended
In Thousands, unless otherwise specified	Jun. 12, 2012	Dec. 31, 2014	Dec. 31, 2013	Jan. 13, 2012	Dec. 31, 2012
Purchase consideration:
Goodwill		$95,505	$95,505
CardStar [Member]
Purchase consideration:
Developed technology				624
Net deferred tax assets				553
Goodwill				4,573
Total assets acquired				5,750
SinglePlatform [Member]
Purchase consideration:
Total cash paid, net of cash acquired	62,546
Cash acquired	311
Fair value of contingent consideration	12,152	0	0		0
Total purchase price consideration	75,009
Developed technology	4,760
Net deferred tax assets	72
Total allocation of purchase price consideration	75,009
Goodwill	71,997
Total assets acquired	77,353
Cash	311
Accounts receivable	48
Prepaid expenses and other current assets	60
Property and equipment	14
Other assets	91
Accounts payable, accrued expenses and other current liabilities	-1,734
Deferred revenue	-610
Total liabilities assumed	($2,344)

Acquisitions_Estimated_Fair_Va

Acquisitions - Estimated Fair Values and Useful Lives of Identifiable Intangible Assets Acquired (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets	$4,760
Total identifiable intangible assets, Weighted Average Useful Life	3 years 11 months 12 days
Developed Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets	850
Total identifiable intangible assets, Weighted Average Useful Life	3 years
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets	2,630
Total identifiable intangible assets, Weighted Average Useful Life	3 years 9 months
Publisher Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets	710
Total identifiable intangible assets, Weighted Average Useful Life	5 years
Trade Name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets	$570
Total identifiable intangible assets, Weighted Average Useful Life	5 years

Acquisitions_Pro_Forma_Results

Acquisitions - Pro Forma Results of Historical Consolidated Statements of Operations (Detail) (SinglePlatform [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012
SinglePlatform [Member]
Business Acquisition [Line Items]
Pro forma revenue	$252,618
Pro forma net income	$11,173

Goodwill_and_Acquired_Intangib2

Goodwill and Acquired Intangible Assets - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	Nov. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Carrying amount of goodwill		$95,505,000	$95,505,000
Impairments to goodwill	0
Amortization expense for intangible assets		$2,195,000	$2,403,000	$1,672,000

Goodwill_and_Acquired_Intangib3

Goodwill and Acquired Intangible Assets - Intangible Assets (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$8,952	$8,952
Accumulated Amortization	6,792	4,597
Net Carrying Amount	2,160	4,355
Developed Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	3 years
Gross Carrying Amount	4,357	4,357
Accumulated Amortization	3,465	2,336
Net Carrying Amount	892	2,021
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	3 years 9 months
Gross Carrying Amount	3,315	3,315
Accumulated Amortization	2,666	1,855
Net Carrying Amount	649	1,460
Publisher Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	5 years
Gross Carrying Amount	710	710
Accumulated Amortization	367	225
Net Carrying Amount	343	485
Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	5 years
Gross Carrying Amount	570	570
Accumulated Amortization	294	181
Net Carrying Amount	$276	$389

Goodwill_and_Acquired_Intangib4

Goodwill and Acquired Intangible Assets - Future Estimated Amortization Expense for Intangible Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]
2015	$1,583
2016	470
2017	107
Net Carrying Amount	$2,160	$4,355

Stockholders_Equity_and_StockB2

Stockholders' Equity and Stock-Based Awards - Additional Information 1 (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2014	Jun. 30, 2014
Stock Issued or Granted During Period, Share-based Compensation [Abstract]
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, par value	$0.01	$0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$0.01	$0.01
Common stock voting rights	One
Stock repurchase program number of shares authorized to be repurchased	553,666
Stock repurchase program average purchase price per share	$29.55
Total cost of stock repurchase	$16,361	$5,366
Stock options, granted	925,700
Weighted average grant-date fair value of stock options granted	$10.71	$7.14	$9.55
Total intrinsic value of stock options exercised	12,394	6,168	6,530
Common Stock [Member]
Stock Issued or Granted During Period, Share-based Compensation [Abstract]
Stock repurchase program number of shares authorized to be repurchased	553,666	285,900
Market value of common stock	$36.70	$31.07
Employees And Directors [Member]
Stock Issued or Granted During Period, Share-based Compensation [Abstract]
Stock options, granted	925,700	875,975	1,549,932
2011 Stock Incentive Plan [Member]
Stock Issued or Granted During Period, Share-based Compensation [Abstract]
Maximum term of incentive stock options, non-statutory stock options, restricted stock, restricted stock units, stock appreciation rights and other stock-based awards	7 years
Common stock shares reserved for issuance				4,200,000
Maximum percentage of fair market value of per unit purchase price	100.00%
Increase in shares of common stock available for issuance	2,100,000
Grant counted towards total number of shares reserved for issuance	1.8			2
Shares of common stock available for issuance	1,754,658
2012 Inducement Plan [Member]
Stock Issued or Granted During Period, Share-based Compensation [Abstract]
Common stock shares reserved for issuance			257,780
Shares of common stock available for issuance	0
Maximum [Member]
Stock Issued or Granted During Period, Share-based Compensation [Abstract]
Stock repurchase program authorized amount of shares repurchased					$30,000
Maximum [Member] | Employees And Directors [Member]
Stock Issued or Granted During Period, Share-based Compensation [Abstract]
Vesting period of restricted awards	4 years
Minimum [Member] | Employees And Directors [Member]
Stock Issued or Granted During Period, Share-based Compensation [Abstract]
Vesting period of restricted awards	3 years

Stockholders_Equity_and_StockB3

Stockholders' Equity and Stock-Based Awards - Value of Stock Option Grants (Detail) (Stock Options [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average risk-free interest rate	1.38%	1.07%	0.81%
Expected term (in years)	4 years 3 months 18 days	4 years 7 months 6 days	4 years 7 months 6 days
Weighted average expected volatility	49.53%	51.14%	53.58%
Expected dividends	0.00%	0.00%	0.00%

Stockholders_Equity_and_StockB4

Stockholders' Equity and Stock-Based Awards - Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Options, Beginning Balance	5,013,983
Number of Options, Granted	925,700
Number of Options, Exercised	-1,039,200
Number of Options, Forfeited	-273,474
Number of Options, Ending Balance	4,627,009	5,013,983
Number of Options, Vested and expected to vest	4,199,125
Number of Options, Exercisable	2,767,887
Weighted Average Exercise Price, Beginning Balance	$19.61
Weighted Average Exercise Price, Granted	$26.01
Weighted Average Exercise Price, Exercised	$19.40
Weighted Average Exercise Price, Forfeited	$22.17
Weighted Average Exercise Price, Ending Balance	$20.79	$19.61
Weighted Average Exercise Price, Vested and expected to vest	$20.53
Weighted Average Exercise Price, Exercisable	$19.67
Weighted Average Remaining Contractual Term, Balance	4 years 10 months 24 days	5 years 6 months 26 days
Weighted Average Remaining Contractual Term, Vested and expected to vest	4 years 9 months 7 days
Weighted Average Remaining Contractual Term, Exercisable	4 years 5 months 1 day
Aggregate Intrinsic Value, Beginning Balance	$57,469
Aggregate Intrinsic Value, Ending Balance	73,638	57,469
Aggregate Intrinsic Value, Vested and expected to vest	67,893
Aggregate Intrinsic Value, Exercisable	$47,143

Stockholders_Equity_and_StockB5

Stockholders' Equity and Stock-Based Awards - Additional Information 2 (Detail) (USD $)	12 Months Ended			1 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share of common stock for each restricted stock unit	1
Aggregate intrinsic value of restricted stock units vested	$7,596	$3,774	$1,485
Number of target shares vesting	4,199,125			4,199,125
Unrecognized compensation expense associated with outstanding stock options, restricted stock and restricted stock units	27,974			27,974
Unrecognized compensation expense associated with outstanding stock options, restricted stock and restricted stock units, weighted-average period	2 years 8 months 27 days
Recognized income tax benefits related to stock-based compensation expense	5,972	5,507	5,354
Capitalized stock-based compensation expense	200	482	785
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units	555,638	371,415	718,930
Weighted average grant-date fair value	$30.23	$22.63	$16.73
Number of restricted stock units will be vest	1,110,158	902,539		1,110,158	902,539
Number of restricted stock units that ultimately vest	704,321			704,321
Intrinsic value of restricted stock units that ultimately vest	25,849			25,849
Restricted stock units, weighted average remaining contractual term	1 year 7 months 10 days
2007 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan offering period	6 months
Percentage of closing market price of common stock equals to per share purchase price for offerings	85.00%
Shares of common stock available for issuance	312,026			312,026
Time-Based Vesting [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units will be vest	534,127			534,127
Time-Based Vesting [Member] | Minimum [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of restricted awards	1 year
Time-Based Vesting [Member] | Maximum [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of restricted awards	4 years
Performance-Based Vesting [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units				108,140	102,803	152,302
Number of restricted stock units will be vest	362,785			362,785
Revenue run rate in restricted stock						$500,000
Number of target shares vesting	0			0
Performance-Based Vesting [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units will be vest	30,000			30,000
Performance-Based Vesting [Member] | Minimum [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of restricted awards				3 years		2 years
Percentage of target shares allowed to vest				50.00%		25.00%
Performance-Based Vesting [Member] | Maximum [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target shares allowed to vest				125.00%		100.00%
Market-Based Vesting Conditions [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units will be vest	213,246			213,246
Market-Based Vesting Conditions [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of target shares vesting	0			0
Number of target shares allowed to vest				84,598	52,498	95,188
Market-Based Vesting Conditions [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target shares allowed to vest				50.00%
Market-Based Vesting Conditions [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target shares allowed to vest				125.00%
Market-Based Vesting Conditions [Member] | Maximum [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant period under risk free interest rate				3 years
2012 Revenue RSUs [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units will be vest	332,785			332,785
2013 Revenue RSUs [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units will be vest	332,785			332,785
Two Thousand And Fourteen Restricted Stock Unit Plan [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units will be vest	332,785			332,785
2014 TSR Units [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units will be vest	213,246			213,246

Stockholders_Equity_and_StockB6

Stockholders' Equity and Stock-Based Awards - Monte Carlo Assumptions (Detail) (Monte Carlo Simulation [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.96%	0.58%	0.34%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	26.28%	29.00%	27.64%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	54.50%	60.36%	62.45%

Stockholders_Equity_and_StockB7

Stockholders' Equity and Stock-Based Awards - Restricted Stock and Restricted Stock Units Activity (Detail) (Restricted Stock Units [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested shares, Beginning Balance	902,539
Restricted units granted	555,638	371,415	718,930
Restricted units vested	-249,352
Restricted units forfeited/cancelled	-98,667
Unvested shares, Ending Balance	1,110,158	902,539
Weighted Average Grant Date Fair Value, Unvested Beginning Balance	$19.40
Weighted Average Grant Date Fair Value, Restricted units granted	$30.23	$22.63	$16.73
Weighted Average Grant Date Fair Value, Restricted units vested	$20.40
Weighted Average Grant Date Fair Value, Restricted units forfeited/cancelled	$17.25
Weighted Average Grant Date Fair Value, Unvested Ending Balance	$24.79	$19.40

Stockholders_Equity_and_StockB8

Stockholders' Equity and Stock-Based Awards - Recognized Stock-Based Compensation Expense (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$16,650	$14,731	$14,274
Cost of Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	2,072	1,802	1,758
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	3,320	3,359	3,733
Sales and Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,866	3,741	3,187
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$6,392	$5,829	$5,596

Income_Taxes_Schedule_of_Compo

Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current income tax expense (benefit)
Federal	$475	($76)	$52
State	1,396	438	474
Total current income tax expense	1,871	362	526
Deferred income tax expense (benefit)
Federal	5,665	2,054	3,299
State	-1,734	-1,160	-644
Total deferred income tax expense (benefit)	3,931	894	2,655
Total income tax expense (benefit)	$5,802	$1,256	$3,181

Income_Taxes_Reconciliation_of

Income Taxes - Reconciliation of Company's Effective Tax Rate to Statutory Federal Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	3.00%	5.00%	2.00%
Impact of permanent differences	3.00%	3.00%	3.00%
Stock options	1.00%	18.00%	11.00%
Tax credits	-14.00%	-49.00%	-6.00%
Provision to return adjustments	1.00%	4.00%	2.00%
Change in the fair value of contingent consideration liability			-27.00%
Other		-1.00%	-1.00%
Statutory federal income tax rate, total	29.00%	15.00%	19.00%

Income_Taxes_Net_Deferred_Tax_

Income Taxes - Net Deferred Tax Assets Related to Temporary Differences and Operating Loss Carry-Forwards (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current:
Accrued expenses	$1,784	$803
Total current	1,784	803
Noncurrent:
Net operating loss carry-forwards		167
Research and development credit carry-forwards	5,169	11,826
Stock options	8,677	7,080
Fixed assets	2,472
Other		62
Total noncurrent	16,318	19,135
Total deferred tax assets	18,102	19,938
Deferred tax liabilities-non-current
Capitalized research and development	-10,439	-7,868
Fixed assets		-72
Intangible assets	-1,217	-1,621
Other	-3
Total deferred tax liabilities-non-current	-11,659	-9,561
Net deferred tax assets	$6,443	$10,377

IncomeTaxes_Additional_Informa

IncomeTaxes - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Line Items]
Changes in valuation allowance			$0	$0	$0
Income tax (expense) benefit	1,855,000	1,324,000
Unrecognized tax benefits	0		0	0	0
Unrecognized tax benefits, accrued interest or tax penalties	0		0	0
Federal [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	8,573,000		8,573,000
Operating loss carry-forwards, expiration dates			Through 2034
Federal [Member] | Research and Development [Member]
Income Taxes [Line Items]
Tax credit carry-forward amount	9,386,000		9,386,000
Tax credit carry-forward, expiration dates			Through 2034
State [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	377,000		377,000
Operating loss carry-forwards, expiration dates			Through 2026
State [Member] | Research and Development [Member]
Income Taxes [Line Items]
Tax credit carry-forward amount	6,782,000		6,782,000
Tax credit carry-forward, expiration dates			Through 2029
State [Member] | Investment Credit [Member]
Income Taxes [Line Items]
Tax credit carry-forward amount	1,444,000		1,444,000
Tax credit carry-forward, expiration dates			Through 2016
State [Member] | Indefinite Carryforward [Member] | Investment Credit [Member]
Income Taxes [Line Items]
Tax credit carry-forward amount	$600,000		$600,000

Accrued_Expenses_Components_of

Accrued Expenses - Components of Accrued Expenses (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]
Payroll and payroll-related	$4,430	$4,106
Licensed software and maintenance	1,197	1,197
Marketing programs	490	575
Other accrued expenses	6,113	5,025
Accrued expenses, total	$12,230	$10,903

401k_Savings_Plan_Additional_I

401(k) Savings Plan - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Plan Disclosure [Line Items]
Contribution by employer to 401 (k) Savings Plan	$3,714	$2,937	$2,457
Employee's Contributions up to 3% [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent	100.00%	100.00%	100.00%
Employee's Contributions Between 3% and 5% [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent	50.00%	50.00%	50.00%
100% of Matching Contribution [Member]
Defined Contribution Plan Disclosure [Line Items]
Percentage of the employee's compensation	3.00%	3.00%	3.00%
50% of Matching Contribution [Member]
Defined Contribution Plan Disclosure [Line Items]
Percentage of the employee's compensation	5.00%	5.00%	5.00%
50% of Matching Contribution [Member] | Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Percentage of the employee's compensation	3.00%	3.00%	3.00%

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leased Assets [Line Items]
Expiration of lease agreement	various dates through 2017
Prepaid expenses and other current assets	$10,723	$9,175
Other assets	1,893	2,345
Loss on sublease	259
Amount of contractual commitments with various vendors	24,093
Letter of credit for the benefit of the landlord	1,300	1,300
Cash balance to secure the letter of credit	1,300	1,300
Office Leases [Member]
Operating Leased Assets [Line Items]
Prepaid rent	51	634
Prepaid expenses and other current assets	3	128
Other assets	48	506
Accrued rent balance	4,232	2,239
Rent expense	9,407	8,149	7,102
Loss on sublease	259
Income on sublease	47
Office Leases [Member] | Accrued Expenses [Member]
Operating Leased Assets [Line Items]
Accrued rent balance included in accrued expenses	577	351
Office Leases [Member] | Other Long-Term Liabilities [Member]
Operating Leased Assets [Line Items]
Accrued rent balance included in other long-term liabilities	3,655	1,888
Third-Party Hosting Agreements [Member]
Operating Leased Assets [Line Items]
Prepaid rent	501	861
Prepaid expenses and other current assets	295	360
Other assets	206	501
Accrued rent balance	172
Rent expense	4,231	4,038	4,073
Number of vendors provide for related services	2
Third-Party Hosting Agreements [Member] | Accrued Expenses [Member]
Operating Leased Assets [Line Items]
Accrued rent balance included in accrued expenses	38
Third-Party Hosting Agreements [Member] | Other Long-Term Liabilities [Member]
Operating Leased Assets [Line Items]
Accrued rent balance included in other long-term liabilities	$134	$173
Headquarters Space [Member]
Operating Leased Assets [Line Items]
Lease expiration date	22-Sep-22
Time period for extension option	10 years
Number of extension option	1
Sales and Support Office [Member]
Operating Leased Assets [Line Items]
Time period for extension option	3 years
Number of extension option	3
Expiration of lease agreement	Apr-19
General Office [Member]
Operating Leased Assets [Line Items]
Expiration of lease agreement	Various dates through 2018

Commitments_and_Contingencies_2

Commitments and Contingencies - Future Minimum Lease Payments under Leases and Agreements (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Office Leases [Member]
Operating Leased Assets [Line Items]
2015	$9,374
2016	10,037
2017	9,981
2018	9,604
2019	8,492
Thereafter	22,462
Total	69,950
Less: Sublease income	678
Net operating lease obligation	69,272
Third-Party Hosting Agreements [Member]
Operating Leased Assets [Line Items]
2015	3,938
2016	4,049
2017	775
Total	$8,762

Quarterly_Information_Unaudite2

Quarterly Information (Unaudited) - Schedule of Quarterly Information (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statements of Operations Data:
Revenue	$88,054	$83,494	$81,256	$78,874	$74,931	$72,039	$70,208	$68,205	$331,678	$285,383	$252,154
Gross profit	64,041	60,271	59,156	57,147	54,279	51,561	49,630	48,297	240,615	203,767	178,607
Income (loss) from operations	7,558	8,083	3,007	1,153	5,498	5,508	-98	-2,613	19,801	8,295	15,516
Net income (loss)	$6,248	$5,198	$2,021	$848	$4,516	$3,320	$32	($654)	$14,315	$7,214	$12,566
Basic net income (loss) per share	$0.20	$0.16	$0.06	$0.03	$0.15	$0.11	$0	($0.02)	$0.45	$0.23	$0.41
Diluted net income (loss) per share	$0.19	$0.16	$0.06	$0.03	$0.14	$0.11	$0	($0.02)	$0.44	$0.23	$0.41