Chegg (CHGG) 10-Q 7 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 31, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	CHEGG, INC
Entity Central Index Key	1,364,954
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		91,347,606

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	[1]
Current assets
Cash and cash equivalents	$ 90,213	$ 67,029
Short-term investments	0	17,800
Accounts receivable, net of allowance for doubtful accounts of $390 and $378 at September 30, 2016 and December 31, 2015, respectively	9,481	13,157
Prepaid expenses	4,018	3,117
Other current assets	35,570	31,732
Total current assets	139,282	132,835
Long-term investments	0	4,229
Textbook library, net	3,956	29,728
Property and equipment, net	30,766	19,971
Goodwill	114,980	91,301
Intangible assets, net	21,659	8,865
Other assets	5,565	4,427
Total assets	316,208	291,356
Current liabilities
Accounts payable	7,992	5,860
Deferred revenue	30,004	14,971
Accrued liabilities	59,034	35,280
Total current liabilities	97,030	56,111
Long-term liabilities
Total other long-term liabilities	4,075	4,170
Total liabilities	101,105	60,281
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.001 par value – 10,000,000 shares authorized, no shares issued and outstanding	0	0
Common stock, $0.001 par value 400,000,000 shares authorized; 91,113,230 and 88,099,983 shares issued and outstanding at September 30, 2016 and December 31, 2015, respectively	91	88
Additional paid-in capital	584,999	560,242
Accumulated other comprehensive loss	(148)	(172)
Accumulated deficit	(369,839)	(329,083)
Total stockholders' equity	215,103	231,075
Total liabilities and stockholders' equity	$ 316,208	$ 291,356
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2015.

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 390	$ 378
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	91,113,230	88,099,983
Common stock, shares outstanding	91,113,230	88,099,983

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net revenues:
Rental	$ 5,511	$ 22,703	$ 32,081	$ 93,199
Services	49,765	33,358	126,795	94,001
Sales	16,067	25,225	32,157	46,019
Total net revenues	71,343	81,286	191,033	233,219
Cost of revenues:
Rental	7,646	27,080	26,505	86,873
Services	12,884	10,377	38,691	32,189
Sales	18,169	24,263	33,833	44,407
Total cost of revenues	38,699	61,720	99,029	163,469
Gross profit	32,644	19,566	92,004	69,750
Operating expenses:
Technology and development	16,241	15,664	49,232	45,076
Sales and marketing	15,256	16,211	41,449	49,985
General and administrative	13,905	12,060	41,140	35,780
Restructuring (credits) charges	(100)	342	(298)	3,320
Loss (gain) on liquidation of textbooks	2,673	(909)	(523)	(2,649)
Total operating expenses	47,975	43,368	131,000	131,512
Loss from operations	(15,331)	(23,802)	(38,996)	(61,762)
Interest expense and other (expense) income, net:
Interest expense, net	(30)	(61)	(151)	(182)
Other (expense) income, net	(148)	85	(146)	217
Total interest expense and other (expense) income, net	(178)	24	(297)	35
Loss before provision for income taxes	(15,509)	(23,778)	(39,293)	(61,727)
Provision for income taxes	554	389	1,463	1,113
Net loss	$ (16,063)	$ (24,167)	$ (40,756)	$ (62,840)
Net loss per share, basic and diluted (in dollars per share)	$ (0.17)	$ (0.28)	$ (0.45)	$ (0.73)
Weighted-average common shares used in computing basic and diluted net loss per share (in shares)	91,059	87,706	90,201	86,419

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (16,063)	$ (24,167)	$ (40,756)	$ (62,840)
Other comprehensive (loss) income:
Change in unrealized gain on available for sale investments	0	16	25	21
Change in foreign currency translation adjustments, net of tax	35	(119)	(1)	(97)
Other comprehensive (loss) income	35	(103)	24	(76)
Total comprehensive loss	$ (16,028)	$ (24,270)	$ (40,732)	$ (62,916)

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016		Sep. 30, 2015
Cash flows from operating activities
Net loss	$ (40,756)		$ (62,840)
Adjustments to reconcile net loss to net cash used in operating activities:
Textbook library depreciation expense	8,903		36,838
Other depreciation and amortization expense	10,001		9,180
Share-based compensation expense	32,701		31,784
Gain on liquidation of textbooks	(523)		(2,649)
Loss from write-offs of textbooks	896		4,534
Other non-cash items	106		790
Change in assets and liabilities, net of acquisition of business:
Accounts receivable	312		(399)
Prepaid expenses and other current assets	(4,712)		(32,503)
Other assets	284		(204)
Accounts payable	2,713		1,977
Deferred revenue	14,896		21,490
Accrued liabilities	5,997		10,310
Other liabilities	(92)		(194)
Net cash provided by operating activities	30,726		18,114
Cash flows from investing activities
Purchases of textbooks	(795)		(32,226)
Proceeds from liquidations of textbooks	23,873		34,230
Purchases of marketable securities	(7,633)		(19,975)
Proceeds from sale of marketable securities	22,830		350
Maturities of marketable securities	6,844		29,989
Purchases of property and equipment	(17,834)		(5,884)
Acquisition of business, net of cash acquired	(25,864)		0
Purchase of strategic equity investment	(1,020)		(2,019)
Net cash provided by investing activities	401		4,465
Cash flows from financing activities
Common stock issued under stock plans, net	1,114		12,588
Payment of taxes related to the net share settlement of RSUs	(9,057)		(8,080)
Repurchase of common stock	0		(2,263)
Net cash (used in) provided by financing activities	(7,943)		2,245
Net increase in cash and cash equivalents	23,184		24,824
Cash and cash equivalents, beginning of period	67,029	[1]	56,117
Cash and cash equivalents, end of period	90,213		80,941
Supplemental cash flow data:
Interest	47		76
Income taxes	831		686
Non-cash investing and financing activities:
Accrued purchases of long-lived assets	1,517		999
Issuance of common stock related to prior acquisition	0		825
Accrued deferred cash consideration related to acquisition	$ 16,650		$ 0
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2015.

Background and Basis of Present

Background and Basis of Presentation	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation	Background and Basis of Presentation Company and Background Chegg, Inc. (Chegg, the Company, we, us, or our), headquartered in Santa Clara, California, was incorporated as a Delaware corporation on July 29, 2005. Chegg is the leading student-first connected learning platform, empowering students to take control of their education to save time, save money, and get smarter. We help students study more effectively for college admissions exams, find the right college to accomplish their goals, get better grades and test scores while in school, and find internships that allow them to gain valuable skills to help them enter the workforce after college. Our connected learning platform offers products and services that help students transition from high school to college to career, with a view toward improving student outcomes and the overall return on investment in education. Basis of Presentation The accompanying condensed consolidated balance sheet as of September 30, 2016 , the condensed consolidated statements of operations and the condensed consolidated statements of comprehensive loss for the three and nine months ended September 30, 2016 and 2015 , the condensed consolidated statements of cash flows for the nine months ended September 30, 2016 and 2015 , and the related footnote disclosures are unaudited. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, including normal recurring adjustments, necessary to present fairly our financial position as of September 30, 2016 , our results of operations for the three and nine months ended September 30, 2016 and 2015 , and cash flows for the nine months ended September 30, 2016 and 2015 . Our results of operations for the three and nine months ended September 30, 2016 and cash flows for the nine months ended September 30, 2016 are not necessarily indicative of the results to be expected for the full year. We operate in a single segment. Our fiscal year ends on December 31 and in this report we refer to the year ended December 31, 2015 as 2015. The condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto, included in our Annual Report on Form 10-K for the year ended December 31, 2015 (the Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). There have been no material changes to our significant accounting policies as compared to the significant accounting policies described in our Annual Report on Form 10-K. Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States (U.S. GAAP) requires management to make estimates, judgments, and assumptions that affect the reported amounts of assets and liabilities; the disclosure of contingent liabilities at the date of the financial statements; and the reported amounts of revenues and expenses during the reporting periods. Significant estimates, assumptions, and judgments are used for, but not limited to: revenue recognition, recoverability of accounts receivable, determination of the useful lives and salvage value assigned to our textbook library, restructuring charges, share-based compensation expense including estimated forfeitures, accounting for income taxes, useful lives assigned to long-lived assets for depreciation and amortization, impairment of goodwill and long-lived assets, and the valuation of acquired tangible and intangible assets. We base our estimates on historical experience, knowledge of current business conditions, and various other factors we believe to be reasonable under the circumstances. These estimates are based on management’s knowledge about current events and expectations about actions we may undertake in the future. Actual results could differ from these estimates, and such differences could be material to our financial position and results of operations. Recent Accounting Pronouncements Except for the 2016 accounting pronouncements, which are described below, there have been no material changes to recent accounting pronouncements as compared to recent accounting pronouncements described in our Annual Report on Form 10-K for the year ended December 31, 2015. In August 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-15 Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) . ASU 2016-15 provides for specific guidance on eight cash flow issues where the previously U.S. GAAP was either unclear or did not include specific guidance. The guidance requires a retrospective application and is effective for annual periods after December 15, 2017, with earlier application permitted as of the beginning of an interim or annual reporting period. We have elected to early adopt this standard which did not result in any changes to the presentation of our condensed consolidated statements of cash flows for the nine months ended September 30, 2016 and 2015 . In May 2016, the FASB issued ASU No. 2016-12 Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients . ASU 2016-12 provides for improvements and practical expedients for specific areas of Topic 606. In April 2016, the FASB issued ASU No. 2016-10 Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing . ASU 2016-10 provides for clarification of two aspects of Topic 606: identifying performance obligations and the licensing implementation guidance. In March 2016, the FASB issued ASU No. 2016-08 Revenue from Contracts with Customers (Topic 606) - Principal versus Agent Considerations (Reporting Revenue Gross versus Net) . ASU No. 2016-08 requires an entity to determine whether the nature of its promise to provide goods or services to a customer is performed in a principal or agent capacity and to recognize revenue in a gross or net manner based on its principal/agent designation. ASUs 2016-12, 2016-10 and 2016-08 allow for companies to choose to apply the standard retrospectively to each prior reporting period presented (full retrospective application) or retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective application). Each guidance is effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Early application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. We plan to adopt the guidance starting in the first quarter of 2018. We are currently in the process of evaluating these guidance updates and have not yet determined the impact on our condensed consolidated financial statements. In March 2016 the FASB issued ASU No. 2016-09 Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . ASU 2016-09 provides for simplification involving several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. In addition to these simplifications, ASU 2016-09 also eliminates the guidance in Topic 718 that was indefinitely deferred shortly after the issuance of FASB Statement No. 123 (revised 2004), Share-Based Payment . Early adoption is permitted and the application of the guidance is different for each update included within ASU 2016-09. The guidance is effective for annual periods after December 15, 2016, and we are currently in the process of evaluating the impact of this new guidance. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . ASU 2016-02 requires an entity to recognize a right-of-use asset and lease liability for all leases with terms of more than 12 months. Recognition, measurement, and presentation of expenses will depend on classification as a finance or operating lease. The amendments in this update also require certain quantitative and qualitative disclosures about leasing arrangements. Early adoption is permitted, and the guidance requires a modified retrospective adoption. The guidance is effective for annual periods after December 15, 2018, and we are currently in the process of evaluating the impact of this new guidance. In January 2016, the FASB issued ASU 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . ASU 2016-01 requires all financial assets and liabilities not accounted for under the equity method to be measured at fair value with the changes in fair value recognized in net income. The amendments in this update also require an entity to separately present in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. In addition, the amendments in this update supersede the requirement to disclose the methods and significant assumptions used in calculating the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet for public business entities. Early adoption is not permitted except for the comprehensive income presentation requirement, and the updated guidance requires a prospective application with a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. The guidance is effective for annual periods after December 15, 2017, and we are currently in the process of evaluating the impact of this new guidance.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, less the weighted-average unvested common stock subject to repurchase or forfeiture. Diluted net loss per share is computed by giving effect to all potential shares of common stock, including stock options, warrants, restricted stock units (RSUs), and performance-based restricted stock units (PSUs), to the extent dilutive. Basic and diluted net loss per share was the same for each period presented as the inclusion of all potential common shares outstanding would have been anti-dilutive. The following table sets forth the computation of historical basic and diluted net loss per share (in thousands, except per share amounts): Three Months Ended Nine Months Ended 2016 2015 2016 2015 Numerator: Net loss $ (16,063 ) $ (24,167 ) $ (40,756 ) $ (62,840 ) Denominator: Weighted average common shares used to compute net loss per share, basic and diluted 91,059 87,706 90,201 86,419 Net loss per share, basic and diluted $ (0.17 ) $ (0.28 ) $ (0.45 ) $ (0.73 ) The following potential weighted-average shares of common stock outstanding were excluded from the computation of diluted net loss per share because including them would have been anti-dilutive (in thousands): Three Months Ended Nine Months Ended 2016 2015 2016 2015 Options to purchase common stock 10,420 8,156 10,917 11,744 RSUs and PSUs 624 317 1,797 159 Employee stock purchase plan — 6 — 14 Warrants to purchase common stock 200 200 200 335 Total common stock equivalents 11,244 8,679 12,914 12,252

Cash and Cash Equivalents, Inve

Cash and Cash Equivalents, Investments and Restricted Cash	9 Months Ended
	Sep. 30, 2016
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents, Investments and Restricted Cash	Cash and Cash Equivalents, Investments and Restricted Cash The following table shows our cash and cash equivalents, restricted cash and investments’ adjusted cost, unrealized gain (loss) and fair value as of September 30, 2016 and December 31, 2015 (in thousands): September 30, 2016 December 31, 2015 Cost Net Unrealized Gain/(Loss) Fair Value Cost Net Unrealized Gain/(Loss) Fair Value Cash and cash equivalents: Cash $ 88,935 $ — $ 88,935 $ 52,905 $ — $ 52,905 Money market funds 1,278 — 1,278 6,672 — 6,672 Commercial paper — — — 5,453 — 5,453 Corporate securities — — — 600 (1 ) 599 Agency bond — — — 1,400 — 1,400 Total cash and cash equivalents $ 90,213 $ — $ 90,213 $ 67,030 $ (1 ) $ 67,029 Short-term investments: Commercial paper $ — $ — $ — $ 3,746 $ — $ 3,746 Corporate securities — — — 10,572 (12 ) 10,560 Agency bonds — — — 3,494 — 3,494 Total short-term investments $ — $ — $ — $ 17,812 $ (12 ) $ 17,800 Long-term investments: Corporate securities $ — $ — $ — $ 3,241 $ (10 ) $ 3,231 Agency bond — — — 1,001 (3 ) 998 Long-term corporate securities $ — $ — $ — $ 4,242 $ (13 ) $ 4,229 Short-term restricted cash $ — $ — $ — $ 300 $ — $ 300 Long-term restricted cash 84 — 84 478 — 478 Total restricted cash $ 84 $ — $ 84 $ 778 $ — $ 778 The amortized cost and fair value of available-for-sale investments as of September 30, 2016 was $1.3 million , respectively, and consist of money market fund deposits which are not due at a single maturity date. As of September 30, 2016 , we did not carry a balance of short-term or long-term investments. Our investment policy generally limits the amount of credit exposure to any one issuer. The policy requires investments generally to be investment grade, with the primary objective of preserving capital and maintaining liquidity. Fair values were determined for each individual security in the investment portfolio. When evaluating an investment for other-than-temporary impairment, we review factors such as the length of time and extent to which fair value has been below its cost basis, the financial condition of the issuer and any changes thereto, changes in market interest rates and our intent to sell or whether it is more likely than not it will be required to sell, and the investment before recovery of the investment’s cost basis. During the nine months ended September 30, 2016 , we did not recognize any impairment charges. Strategic Investment During the three months ended September 30, 2016 and 2015 , we invested $1.0 million and $2.0 million , respectively, in a third party to expand our customer reach. Our total investment of $3.0 million is included in other assets on our condensed consolidated balance sheet. We did not record other-than-temporary impairment charges on this investment during the three and nine months ended September 30, 2016 and 2015 , respectively, as there were no significant identified events or changes in circumstances that would be considered an indicator for impairment.

Fair Value Measurement

Fair Value Measurement	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement We have established a fair value hierarchy used to determine the fair value of our financial instruments as follows: Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. Level 2—Inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments. Level 3—Inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value; the inputs require significant management judgment or estimation. A financial instrument’s classification within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Financial instruments measured and recorded at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2016 Total Quoted Prices Significant Assets: Cash equivalents: Money market funds $ 1,278 $ 1,278 $ — Total assets measured and recorded at fair value $ 1,278 $ 1,278 $ — December 31, 2015 Total Quoted Prices Significant Assets: Cash equivalents: Money market funds $ 6,672 $ 6,672 $ — Commercial paper 5,453 — 5,453 Corporate securities 599 — 599 Agency bond 1,400 — 1,400 Short-term investments: Commercial paper 3,746 — 3,746 Corporate securities 10,560 — 10,560 Agency bonds 3,494 — 3,494 Long-term investments: Corporate securities 3,231 — 3,231 Agency bond 998 — 998 Total assets measured and recorded at fair value $ 36,153 $ 6,672 $ 29,481 We value our marketable securities based on quoted prices in active markets for identical assets (Level 1 inputs) or inputs other than quoted prices that are observable either directly or indirectly (Level 2 inputs) in determining fair value. We classify all of our fixed income available-for-sale securities as having Level 2 inputs. The valuation techniques used to measure the fair value of our financial instruments having Level 2 inputs were derived from non-binding market consensus prices that are corroborated by observable market data, quoted market prices for similar instruments, or pricing models such as discounted cash flow techniques. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while we believe our valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date.

Acquisition

Acquisition	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Acquisition	Acquisition In May 2016 , we acquired all of the outstanding interests of Imagine Easy Solutions, LLC (Imagine Easy), a privately held online learning company based in New York that provides a portfolio of online writing tools. We anticipate this acquisition to enhance our ability to acquire new students, increase the value of our platform to our existing students, and have a meaningful and positive impact on their outcomes. The total fair value of the purchase consideration was $42.3 million . The purchase consideration included deferred cash consideration of $17.0 million , of which the present value of $16.7 million was recorded as accrued liabilities on our condensed consolidated balance sheet as of September 30, 2016 . We will accrete into the deferred cash consideration of $17.0 million until it is paid to the sellers in April 2017. During the three and nine months ended September 30, 2016 , we recorded accretion expense of $0.2 million and $0.3 million , respectively, through other expense on the condensed consolidated statement of operations. Further, the consideration included an escrow and a hold-back amount of $4.2 million and $0.5 million , respectively, for general representations and warranties and potential post-closing adjustments. The escrow amount will be released in July 2017, and the hold-back amount was released during the third quarter of 2016. The acquisition date fair value of the purchase consideration for the above transaction consisted of the following (in thousands): Initial cash consideration $ 21,023 Net working capital adjustment 200 Fair value of deferred cash consideration 16,374 Escrow 4,200 Hold-back 500 Fair value of purchase consideration $ 42,297 Included in the purchase agreement are additional contingent payments of up to $18.0 million , of which $3.0 million relates to the achievement of performance conditions for the fiscal year ended 2016 . These payments will be made over the next three years, subject to continued employment of the sellers, and will be expensed ratably as technology and development and general and administrative expense on our condensed consolidated statements of operations. These contingent payments may be settled by us, at our sole discretion, either in cash or shares of our common stock. We have accrued $2.5 million as of September 30, 2016 for these contingent payments which is included within accrued liabilities on our condensed consolidated balance sheet. The fair value of the intangible assets acquired was determined under the acquisition method of accounting for business combinations. The excess of purchase consideration paid over the fair value of identifiable assets acquired was recorded as goodwill. Goodwill is primarily attributable to the potential for future product offerings as well as our expanded student reach. The amounts recorded for goodwill are expected to be deductible for tax purposes. The following table presents the total purchase price allocation recorded in our condensed consolidated balance sheets as of the acquisition date (in thousands): Cash $ 59 Accounts receivable 2,610 Favorable lease acquired 300 Other acquired assets 212 Acquired intangible assets: Trade names 1,800 Domain names 1,100 Advertiser relationships 6,600 User base 410 Non-compete agreements 500 Developed technology 5,600 Total acquired intangible assets 16,010 Total identifiable assets acquired 19,191 Liabilities assumed (573 ) Net identifiable assets acquired 18,618 Goodwill 23,679 Total purchase consideration $ 42,297 During the nine months ended September 30, 2016 , we incurred $1.0 million of acquisition-related expenses associated with the acquisition of Imagine Easy which have been included in general and administrative expenses in our condensed consolidated statements of operations. The pro forma results of operations of the above acquisition have not been presented as the financial impact to our condensed consolidated statements of operations is not material.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill consists of the following (in thousands): September 30, 2016 December 31, 2015 Beginning balance $ 91,301 $ 91,301 Addition due to acquisition 23,679 — Ending balance $ 114,980 $ 91,301 Intangible assets as of September 30, 2016 and December 31, 2015 consist of the following (in thousands, except weighted-average amortization period): September 30, 2016 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 60 $ 15,017 $ (7,779 ) $ 7,238 Customer lists 47 9,830 (3,192 ) 6,638 Trade names 48 5,243 (1,661 ) 3,582 Non-compete agreements 30 1,720 (1,177 ) 543 Master service agreements 21 1,030 (972 ) 58 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 36,440 $ (14,781 ) $ 21,659 December 31, 2015 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 52 $ 9,417 $ (6,702 ) $ 2,715 Customer lists 20 2,820 (2,239 ) 581 Trade names 48 2,343 (920 ) 1,423 Non-compete agreements 28 1,220 (832 ) 388 Master service agreements 21 1,030 (872 ) 158 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 20,430 $ (11,565 ) $ 8,865 During the three and nine months ended September 30, 2016 , amortization expense related to our acquired intangible assets totaled approximately $1.4 million and $3.2 million , respectively. During the three and nine months ended September 30, 2015 , amortization expense related to our acquired intangible assets totaled approximately $1.1 million and $4.1 million , respectively. As of September 30, 2016 , the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands): Remaining three months of 2016 $ 1,376 2017 5,153 2018 4,255 2019 3,433 2020 2,153 Thereafter 1,689 Total $ 18,059

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Debt Obligations	Debt Obligations In September 2016 , we entered into a revolving line of credit with an aggregate principal amount of $30.0 million (the Line of Credit) with an accordion feature that, subject to the lender's discretion, allows us to borrow up to a total of $50.0 million . This new line of credit replaces the previous line of credit that expired in August 2016. The Line of Credit matures September 2019 and requires us to repay the outstanding balance upon maturity. We will pay a fee equal to 0.25% per year on the average daily unused amount of the Line of Credit and a base interest rate equal to the LIBOR. In addition, we will pay a fee for each issued letter of credit which will be determined based on our current leverage ratio at the time the letter of credit is issued. If our leverage ratio is less than 1.00% , we will pay a fee equal to 1.50% per year and if our leverage ratio is greater than or equal to 1.00% , we will pay a fee equal to 2.50% per year. Our leverage ratio is a ratio of all obligations owed to the bank divided by our consolidated EBITDA. EBITDA for the purposes of calculating our leverage ratio is defined as net profit (loss) before tax, plus interest expense, plus non-cash stock compensation (net of capitalized interest expense), depreciation expense, amortization expense and other non-cash expenses (assuming there are no future cash costs), plus expenses incurred in connection with permitted acquisitions (including without limitation accrued acquisition-related contingent expenses) in an amount not to exceed $6.0 million per calendar year, plus non-recurring expenses in an amount not to exceed $2.0 million per calendar year. We must maintain financial covenants under the Line of Credit as follows: (1) maintain a balance of unrestricted cash at the Bank of not less than $30.0 million at all times, other than the three months ending March 31, 2017 and June 30, 2017 , and not less than $25.0 million during the three months ending March 31, 2017 and June 30, 2017 ; and (2) achieve EBITDA, on a trailing 12 month basis, of not less than (i) $25.0 million for the period of time from September 30, 2016 through June 30, 2017 , (ii) $30.0 million for the period of time from September 30, 2017 through June 30, 2018 , and (iii) $35.0 million for the period of time from September 30, 2018 through the maturity of the Line of Credit. As of December 31, 2015 , we had a revolving credit facility with an aggregate principal amount of $30.0 million (the Revolving Credit Facility) with an accordion feature that, subject to certain financial criteria, allowed us to borrow up to a total of $65.0 million beginning the quarter ended December 31, 2015. The Revolving Credit Facility carried, at our election, a base interest rate of the greater of the Federal Funds Rate plus 0.5% or one-month LIBOR plus 1% or a LIBOR based interest rate plus additional interest of up to 4.5% depending on our leverage ratio. The Revolving Credit Facility expired in August 2016. As of September 30, 2016 , we were in compliance with the financial covenants of the Line of Credit. Further, we had no amounts outstanding and were able to borrow up to $30.0 million under the Line of Credit.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We lease our office and warehouse facilities under operating leases, which expire at various dates through 2021 . Our primary operating lease commitments at September 30, 2016 related to our headquarters in Santa Clara, California, our office in San Francisco, California, and our warehouse facility in Shepherdsville, Kentucky. We recognize rent expense on a straight-line basis over the lease period. Where leases contain escalation clauses, rent abatements, or concessions, such as rent holidays and landlord or tenant incentives or allowances, we apply them in the determination of straight-line rent expense over the lease term. As a result of our strategic partnership with Ingram and the exit of our Kentucky warehouse during 2015 , we have subleased substantially all of our warehouse in Kentucky and we expect this sublease agreement to generate $0.2 million of sublease income per month through the end of the lease term in November 2016. Rental expense, net of sublease income, was approximately $0.5 million and $1.4 million in the three and nine months ended September 30, 2016 , respectively, and $0.6 million and $2.0 million in the three and nine months ended September 30, 2015 , respectively. From time to time, third parties may assert patent infringement claims against us in the form of letters, litigation, or other forms of communication. In addition, we may from time to time be subject to other legal proceedings and claims in the ordinary course of business, including claims of alleged infringement of trademarks, copyrights, and other intellectual property rights; employment claims; and general contract or other claims. We may also, from time to time, be subject to various legal or government claims, disputes, or investigations. Such matters may include, but not be limited to, claims, disputes, or investigations related to warranty, refund, breach of contract, employment, intellectual property, government regulation, or compliance or other matters. In July 2010, the Kentucky Tax Authority issued a property tax assessment of approximately $1.0 million related to our textbook library located in our Kentucky warehouse for the 2009 and 2010 tax years under audit. In March 2011, we filed a protest with the Kentucky Board of Tax Appeals that was rejected in March 2012. In September 2012, we filed a complaint seeking declaratory rights against the Commonwealth of Kentucky in the Bullitt Circuit Court of Kentucky, and that case was subsequently dismissed in favor of administration remedies with the Kentucky Tax Authority. We received a final Notice of Tax due in October 2012 from the Kentucky Tax Authority, and we appealed this notice in November 2012 with the Kentucky Board of Tax Appeals. In May 2013, we presented an Offer in Judgment to the Kentucky Tax Authority of approximately $150,000 , excluding tax and penalties, an amount that we have accrued for the two years under audit. We accrued this amount as of December 31, 2012. We appealed to the Kentucky Board of Tax Appeals in July 2013, and the Board issued a ruling in favor of the Kentucky Department of Revenue in January 2014 maintaining the property tax assessment. In February 2014, we filed an appeal to the Franklin Circuit Court in Kentucky, and in June 2014 the Circuit Court held in abeyance our motion to appeal. In October 2014 the Franklin Circuit Court in Kentucky issued its opinion and order reversing the Board of Tax Appeal's decision, setting aside the Kentucky Department of Revenue's tax assessments against us and further vacating all penalties and interest. The Kentucky Department of Revenue has appealed the Circuit Court ruling. On March 4, 2016, the Kentucky Court of Appeals ruled unanimously in our favor, affirming our position that no property tax was owed on the textbooks. The Kentucky Department of Revenue petitioned the Kentucky Supreme Court for a discretionary review, which was denied in September 2016. The case was determined in our favor with no property tax due related to our textbook library. We are not aware of any other pending legal matters or claims, individually or in the aggregate, that are expected to have a material adverse impact on our consolidated financial position, results of operations, or cash flows. However, our determination of whether a claim will proceed to litigation cannot be made with certainty, nor can the results of litigation be predicted with certainty. Nevertheless, defending any of these actions, regardless of the outcome, may be costly, time consuming, distract management personnel, and have a negative effect on our business. An adverse outcome in any of these actions, including a judgment or settlement, may cause a material adverse effect on our future business, operating results, and/or financial condition.

Guarantees and Indemnifications

Guarantees and Indemnifications	9 Months Ended
	Sep. 30, 2016
Guarantees And Indemnifications [Abstract]
Guarantees and Indemnifications	Guarantees and Indemnifications We have agreed to indemnify our directors and officers for certain events or occurrences, subject to certain limits, while such persons are or were serving at our request in such capacity. We may terminate the indemnification agreements with these persons upon termination of employment, but termination will not affect claims for indemnification related to events occurring prior to the effective date of termination. We have a directors’ and officers’ insurance policy that limits our potential exposure up to the limits of our insurance coverage. In addition, we also have other indemnification agreements with various vendors against certain claims, liabilities, losses, and damages. The maximum amount of potential future indemnification is unlimited. We believe the fair value of these indemnification agreements is minimal. We have not recorded any liabilities for these agreements as of September 30, 2016 .

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholders' Equity	Stockholders' Equity Share-based Compensation Total share-based compensation expense recorded for employees and non-employees, is as follows (in thousands): Three Months Ended Nine Months Ended 2016 2015 2016 2015 Cost of revenues $ 46 $ 103 $ 115 $ 318 Technology and development 3,449 3,464 11,207 9,444 Sales and marketing 1,605 126 5,456 6,214 General and administrative 5,110 5,240 15,923 15,808 Total share-based compensation expense $ 10,210 $ 8,933 $ 32,701 $ 31,784 There was no capitalized share-based compensation expense as of September 30, 2016 or 2015 . Fair Value of Restricted Stock Units (RSUs) and of Performance-Based Restricted Stock Units (PSUs) RSUs and PSUs are converted into shares of our common stock upon vesting on a one-for-one basis. Vesting of RSUs is subject to the employee’s continuing service to us, while vesting of PSUs is subject to our achievement of specified corporate financial performance objectives in addition to the employee's continuing service to us. The compensation expense related to RSUs and PSUs is determined using the fair value of our common stock on the date of grant, and the expense is recognized on a straight-line basis over the vesting period. RSUs are typically fully vested at the end of three or four years while PSUs vest subject to the achievement of performance objectives and if achieved, typically vest over two to three years . We assess the achievement of performance objectives on a quarterly basis and adjust our share-based payment expense as appropriate. Fair Value of 2013 Employee Stock Purchase Plan (2013 ESPP) Under the 2013 ESPP, rights to purchase shares are generally granted during the second and fourth quarter of each year. We estimate the fair value of rights granted under the 2013 ESPP at the date of grant using the Black-Scholes-Merton option-pricing model. Stock Option Activity During the nine months ended September 30, 2016 and 2015 , we granted 232,700 and 165,456 stock option awards, respectively, at a weighted average grant date fair value of $2.58 and $3.63 , respectively, solely to members of our board of directors. We did not grant stock option awards during the three months ended September 30, 2016 and 2015 . As of September 30, 2016 , our total unrecognized compensation expense for stock option awards granted to employees, officers, directors, and consultants was approximately $2.9 million , which will be recognized over a weighted-average vesting period of approximately 0.8 years . RSU and PSU Activity RSUs and PSUs Outstanding Number of RSUs and PSUs Outstanding Weighted Average Grant Date Fair Value Balance at December 31, 2015 13,270,650 $ 6.38 Granted 9,620,354 4.44 Released (4,558,359 ) 6.48 Canceled (3,931,959 ) 6.09 Balance at September 30, 2016 14,400,686 $ 5.13 2015 PSU Grant In February 2015, we granted PSUs under the 2013 Equity Incentive Plan (2013 Plan) to certain of our key employees (the February 2015 grants). The PSUs entitle the employees to receive a certain number of shares of our common stock based on our satisfaction of certain financial and strategic performance targets during 2015 (the 2015 Performance Period) and 2016 (the 2016 Performance Period). Based on the achievement of the performance conditions during the 2015 Performance Period for the February 2015 grants, the final settlement met the minimum threshold for the 2015 Performance Period based on a specified objective formula approved by the Compensation Committee of the Board of Directors (the Compensation Committee). The PSUs related to the 2015 Performance Period vest annually over a one or three year period depending on the employee, with the initial vesting occurring in February 2016. In March 2016, the financial and strategic performance targets were set by the Compensation Committee for the 2016 Performance Period for the February 2015 grants. The PSUs related to the 2016 Performance Period vest over a one year period with vesting occurring in March 2017. During the nine months ended September 30, 2016 , the Compensation Committee approved a modification of the performance targets related to the 2015 Performance Period of the February 2015 grants for 26 employees. As a result of the modification, we recorded an expense of $1.5 million during the nine months ended September 30, 2016 . The number of shares underlying the PSUs granted during the nine months ended September 30, 2015 totaled 2,300,824 shares and had a weighted average grant date fair value of $6.59 per share. During the nine months ended September 30, 2016 , 688,464 shares were released relating to the 2015 Performance Period. As of September 30, 2016 , we expect a significant portion of the remaining PSUs related to the 2016 Performance Period to vest. 2016 PSU Grants In March 2016, we granted PSUs under the 2013 Plan to certain of our key executives. The PSUs entitle the executives to receive a certain number of shares of our common stock based on our satisfaction of certain financial and strategic performance targets during 2016. Based on the achievement of the performance conditions during 2016 for the March 2016 grants, the final settlement will range between zero and 100% of the maximum shares underlying the PSU awards based on a specified objective formula approved by the Compensation Committee. If earned, these PSUs will vest over a three year period depending on the employee, with the initial vesting occurring in March 2018. The number of shares underlying the PSUs granted during the nine months ended September 30, 2016 totaled 2,377,842 shares and had a weighted average grant date fair value of $4.32 per share. As of September 30, 2016 , we expect a significant portion of these PSUs to vest. As of September 30, 2016 , we had a total of approximately $40.0 million of unrecognized compensation costs related to RSUs and PSUs that are expected to be recognized over the remaining weighted average period of 2.0 years .

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We recorded an income tax provision of approximately $0.6 million and $1.5 million for the three and nine months ended September 30, 2016 , respectively, and an income tax provision of approximately $0.4 million and $1.1 million for the three and nine months ended September 30, 2015 , respectively. The income tax provision for the three and nine months ended September 30, 2016 was primarily due to state and foreign income tax expense and federal tax expense related to tax amortization of acquired indefinite lived intangible assets. The income tax provision for the three and nine months ended September 30, 2015 was primarily due to state and foreign income tax expense and federal tax expense related to the tax amortization of acquired goodwill.

Restructuring (Credits) Charges

Restructuring (Credits) Charges	9 Months Ended
	Sep. 30, 2016
Restructuring and Related Activities [Abstract]
Restructuring (Credits) Charges	Restructuring (Credits) Charges The following table summarizes the activity related to the accrual for restructuring charges (in thousands): Workforce Reduction Costs Lease Termination and Other Costs Total Balance at January 1, 2015 $ — $ — $ — Restructuring charges 1,885 2,983 4,868 Cash payments (1,830 ) (675 ) (2,505 ) Write-offs — (317 ) (317 ) Other — 472 472 Balance at December 31, 2015 55 2,463 2,518 Restructuring credits — (298 ) (298 ) Cash payments (55 ) (1,564 ) (1,619 ) Balance at September 30, 2016 $ — $ 601 $ 601 2015 Restructuring Plan Restructuring charges recorded in 2015 were related to our exits from our print coupon business and our Kentucky warehouse. As a result of our strategic partnership with Ingram, we successfully exited our warehouse facilities during 2015. Restructuring credits of $0.3 million recorded during the three and nine months ended September 30, 2016 were primarily related to a partial reversal of previously accrued lease termination costs due to our subtenant leasing additional space. Costs incurred to date related to the lease termination and other costs are expected to be fully paid by 2021. As of September 30, 2016 , the $0.6 million liability was comprised of a short-term accrual of $0.5 million included within accrued liabilities and a long-term accrual of $0.1 million included within other liabilities on the condensed consolidated balance sheets.

Related-Party Transactions

Related-Party Transactions	9 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Related-Party Transactions	Related-Party Transactions Our Chief Executive Officer is a member of the Board of Directors of Adobe Systems Incorporated (Adobe). During the three and nine months ended September 30, 2016 , we had purchases of $0.7 million and $2.5 million , respectively, and during the three and nine months ended September 30, 2015 , we had purchases of $1.1 million and $2.0 million , respectively, of products from Adobe. We had no revenues in the three and nine months ended September 30, 2016 and $0.1 million in the nine months ended September 30, 2015 from Adobe. We had $0.7 million and $0.4 million in payables as of September 30, 2016 and December 31, 2015 , respectively, to Adobe. We had no outstanding accounts receivables as of September 30, 2016 and December 31, 2015 from Adobe. One of our board members is also a member of the Board of Directors of Cengage Learning, Inc. (Cengage). During the three and nine months ended September 30, 2016 , we had purchases of $2.8 million and $7.2 million , respectively, and during the three and nine months ended September 30, 2015 , we had purchases of $2.9 million and $9.1 million , respectively, of products from Cengage. We had $0.6 million in revenues in both the three and nine months ended September 30, 2016 and $0.1 million in revenues in both the three and nine months ended September 30, 2015 from Cengage. We had an immaterial amount in payables as of September 30, 2016 and December 31, 2015 to Cengage. We had $0.1 million in outstanding accounts receivables as of September 30, 2016 and no outstanding accounts receivables as of December 31, 2015 from Cengage. One of our board members is also a member of the Board of Directors of Groupon, Inc. (Groupon). During the three and nine months ended September 30, 2016 , we had purchases of $0.2 million and $0.5 million , respectively, and an immaterial amount during the three and nine months ended September 30, 2015 of services from Groupon. We had no revenues in the three and nine months ended September 30, 2016 and September 30, 2015 from Groupon. We had an immaterial amount in payables as of September 30, 2016 and December 31, 2015 , respectively, to Groupon. We had no outstanding accounts receivables as of September 30, 2016 and December 31, 2015 from Groupon. Transactions with the above related parties have been conducted on an arms-length basis, and the terms of our contracts are consistent with our contracts with other independent parties.

Background and Basis of Prese20

Background and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated balance sheet as of September 30, 2016 , the condensed consolidated statements of operations and the condensed consolidated statements of comprehensive loss for the three and nine months ended September 30, 2016 and 2015 , the condensed consolidated statements of cash flows for the nine months ended September 30, 2016 and 2015 , and the related footnote disclosures are unaudited. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, including normal recurring adjustments, necessary to present fairly our financial position as of September 30, 2016 , our results of operations for the three and nine months ended September 30, 2016 and 2015 , and cash flows for the nine months ended September 30, 2016 and 2015 . Our results of operations for the three and nine months ended September 30, 2016 and cash flows for the nine months ended September 30, 2016 are not necessarily indicative of the results to be expected for the full year. We operate in a single segment. Our fiscal year ends on December 31 and in this report we refer to the year ended December 31, 2015 as 2015. The condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto, included in our Annual Report on Form 10-K for the year ended December 31, 2015 (the Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). There have been no material changes to our significant accounting policies as compared to the significant accounting policies described in our Annual Report on Form 10-K.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States (U.S. GAAP) requires management to make estimates, judgments, and assumptions that affect the reported amounts of assets and liabilities; the disclosure of contingent liabilities at the date of the financial statements; and the reported amounts of revenues and expenses during the reporting periods. Significant estimates, assumptions, and judgments are used for, but not limited to: revenue recognition, recoverability of accounts receivable, determination of the useful lives and salvage value assigned to our textbook library, restructuring charges, share-based compensation expense including estimated forfeitures, accounting for income taxes, useful lives assigned to long-lived assets for depreciation and amortization, impairment of goodwill and long-lived assets, and the valuation of acquired tangible and intangible assets. We base our estimates on historical experience, knowledge of current business conditions, and various other factors we believe to be reasonable under the circumstances. These estimates are based on management’s knowledge about current events and expectations about actions we may undertake in the future. Actual results could differ from these estimates, and such differences could be material to our financial position and results of operations.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Except for the 2016 accounting pronouncements, which are described below, there have been no material changes to recent accounting pronouncements as compared to recent accounting pronouncements described in our Annual Report on Form 10-K for the year ended December 31, 2015. In August 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-15 Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) . ASU 2016-15 provides for specific guidance on eight cash flow issues where the previously U.S. GAAP was either unclear or did not include specific guidance. The guidance requires a retrospective application and is effective for annual periods after December 15, 2017, with earlier application permitted as of the beginning of an interim or annual reporting period. We have elected to early adopt this standard which did not result in any changes to the presentation of our condensed consolidated statements of cash flows for the nine months ended September 30, 2016 and 2015 . In May 2016, the FASB issued ASU No. 2016-12 Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients . ASU 2016-12 provides for improvements and practical expedients for specific areas of Topic 606. In April 2016, the FASB issued ASU No. 2016-10 Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing . ASU 2016-10 provides for clarification of two aspects of Topic 606: identifying performance obligations and the licensing implementation guidance. In March 2016, the FASB issued ASU No. 2016-08 Revenue from Contracts with Customers (Topic 606) - Principal versus Agent Considerations (Reporting Revenue Gross versus Net) . ASU No. 2016-08 requires an entity to determine whether the nature of its promise to provide goods or services to a customer is performed in a principal or agent capacity and to recognize revenue in a gross or net manner based on its principal/agent designation. ASUs 2016-12, 2016-10 and 2016-08 allow for companies to choose to apply the standard retrospectively to each prior reporting period presented (full retrospective application) or retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective application). Each guidance is effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Early application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. We plan to adopt the guidance starting in the first quarter of 2018. We are currently in the process of evaluating these guidance updates and have not yet determined the impact on our condensed consolidated financial statements. In March 2016 the FASB issued ASU No. 2016-09 Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . ASU 2016-09 provides for simplification involving several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. In addition to these simplifications, ASU 2016-09 also eliminates the guidance in Topic 718 that was indefinitely deferred shortly after the issuance of FASB Statement No. 123 (revised 2004), Share-Based Payment . Early adoption is permitted and the application of the guidance is different for each update included within ASU 2016-09. The guidance is effective for annual periods after December 15, 2016, and we are currently in the process of evaluating the impact of this new guidance. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . ASU 2016-02 requires an entity to recognize a right-of-use asset and lease liability for all leases with terms of more than 12 months. Recognition, measurement, and presentation of expenses will depend on classification as a finance or operating lease. The amendments in this update also require certain quantitative and qualitative disclosures about leasing arrangements. Early adoption is permitted, and the guidance requires a modified retrospective adoption. The guidance is effective for annual periods after December 15, 2018, and we are currently in the process of evaluating the impact of this new guidance. In January 2016, the FASB issued ASU 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . ASU 2016-01 requires all financial assets and liabilities not accounted for under the equity method to be measured at fair value with the changes in fair value recognized in net income. The amendments in this update also require an entity to separately present in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. In addition, the amendments in this update supersede the requirement to disclose the methods and significant assumptions used in calculating the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet for public business entities. Early adoption is not permitted except for the comprehensive income presentation requirement, and the updated guidance requires a prospective application with a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. The guidance is effective for annual periods after December 15, 2017, and we are currently in the process of evaluating the impact of this new guidance.
Net Loss Per Share	Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, less the weighted-average unvested common stock subject to repurchase or forfeiture. Diluted net loss per share is computed by giving effect to all potential shares of common stock, including stock options, warrants, restricted stock units (RSUs), and performance-based restricted stock units (PSUs), to the extent dilutive. Basic and diluted net loss per share was the same for each period presented as the inclusion of all potential common shares outstanding would have been anti-dilutive.

Net Loss Per Share Net Loss Per

Net Loss Per Share Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the computation of historical basic and diluted net loss per share (in thousands, except per share amounts): Three Months Ended Nine Months Ended 2016 2015 2016 2015 Numerator: Net loss $ (16,063 ) $ (24,167 ) $ (40,756 ) $ (62,840 ) Denominator: Weighted average common shares used to compute net loss per share, basic and diluted 91,059 87,706 90,201 86,419 Net loss per share, basic and diluted $ (0.17 ) $ (0.28 ) $ (0.45 ) $ (0.73 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following potential weighted-average shares of common stock outstanding were excluded from the computation of diluted net loss per share because including them would have been anti-dilutive (in thousands): Three Months Ended Nine Months Ended 2016 2015 2016 2015 Options to purchase common stock 10,420 8,156 10,917 11,744 RSUs and PSUs 624 317 1,797 159 Employee stock purchase plan — 6 — 14 Warrants to purchase common stock 200 200 200 335 Total common stock equivalents 11,244 8,679 12,914 12,252

Cash and Cash Equivalents, In22

Cash and Cash Equivalents, Investments and Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2016
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents, Restricted Cash and Investments	The following table shows our cash and cash equivalents, restricted cash and investments’ adjusted cost, unrealized gain (loss) and fair value as of September 30, 2016 and December 31, 2015 (in thousands): September 30, 2016 December 31, 2015 Cost Net Unrealized Gain/(Loss) Fair Value Cost Net Unrealized Gain/(Loss) Fair Value Cash and cash equivalents: Cash $ 88,935 $ — $ 88,935 $ 52,905 $ — $ 52,905 Money market funds 1,278 — 1,278 6,672 — 6,672 Commercial paper — — — 5,453 — 5,453 Corporate securities — — — 600 (1 ) 599 Agency bond — — — 1,400 — 1,400 Total cash and cash equivalents $ 90,213 $ — $ 90,213 $ 67,030 $ (1 ) $ 67,029 Short-term investments: Commercial paper $ — $ — $ — $ 3,746 $ — $ 3,746 Corporate securities — — — 10,572 (12 ) 10,560 Agency bonds — — — 3,494 — 3,494 Total short-term investments $ — $ — $ — $ 17,812 $ (12 ) $ 17,800 Long-term investments: Corporate securities $ — $ — $ — $ 3,241 $ (10 ) $ 3,231 Agency bond — — — 1,001 (3 ) 998 Long-term corporate securities $ — $ — $ — $ 4,242 $ (13 ) $ 4,229 Short-term restricted cash $ — $ — $ — $ 300 $ — $ 300 Long-term restricted cash 84 — 84 478 — 478 Total restricted cash $ 84 $ — $ 84 $ 778 $ — $ 778

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Financial Instruments Measured and Recorded at Fair Value on Recurring Basis	Financial instruments measured and recorded at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2016 Total Quoted Prices Significant Assets: Cash equivalents: Money market funds $ 1,278 $ 1,278 $ — Total assets measured and recorded at fair value $ 1,278 $ 1,278 $ — December 31, 2015 Total Quoted Prices Significant Assets: Cash equivalents: Money market funds $ 6,672 $ 6,672 $ — Commercial paper 5,453 — 5,453 Corporate securities 599 — 599 Agency bond 1,400 — 1,400 Short-term investments: Commercial paper 3,746 — 3,746 Corporate securities 10,560 — 10,560 Agency bonds 3,494 — 3,494 Long-term investments: Corporate securities 3,231 — 3,231 Agency bond 998 — 998 Total assets measured and recorded at fair value $ 36,153 $ 6,672 $ 29,481

Acquisition (Tables)

Acquisition (Tables)	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition	The acquisition date fair value of the purchase consideration for the above transaction consisted of the following (in thousands): Initial cash consideration $ 21,023 Net working capital adjustment 200 Fair value of deferred cash consideration 16,374 Escrow 4,200 Hold-back 500 Fair value of purchase consideration $ 42,297
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The following table presents the total purchase price allocation recorded in our condensed consolidated balance sheets as of the acquisition date (in thousands): Cash $ 59 Accounts receivable 2,610 Favorable lease acquired 300 Other acquired assets 212 Acquired intangible assets: Trade names 1,800 Domain names 1,100 Advertiser relationships 6,600 User base 410 Non-compete agreements 500 Developed technology 5,600 Total acquired intangible assets 16,010 Total identifiable assets acquired 19,191 Liabilities assumed (573 ) Net identifiable assets acquired 18,618 Goodwill 23,679 Total purchase consideration $ 42,297

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Goodwill consists of the following (in thousands): September 30, 2016 December 31, 2015 Beginning balance $ 91,301 $ 91,301 Addition due to acquisition 23,679 — Ending balance $ 114,980 $ 91,301
Schedule of Acquired Finite-Lived Intangible Assets by Major Class	Intangible assets as of September 30, 2016 and December 31, 2015 consist of the following (in thousands, except weighted-average amortization period): September 30, 2016 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 60 $ 15,017 $ (7,779 ) $ 7,238 Customer lists 47 9,830 (3,192 ) 6,638 Trade names 48 5,243 (1,661 ) 3,582 Non-compete agreements 30 1,720 (1,177 ) 543 Master service agreements 21 1,030 (972 ) 58 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 36,440 $ (14,781 ) $ 21,659 December 31, 2015 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 52 $ 9,417 $ (6,702 ) $ 2,715 Customer lists 20 2,820 (2,239 ) 581 Trade names 48 2,343 (920 ) 1,423 Non-compete agreements 28 1,220 (832 ) 388 Master service agreements 21 1,030 (872 ) 158 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 20,430 $ (11,565 ) $ 8,865
Schedule of Acquired Indefinite-lived Intangible Assets by Major Class	Intangible assets as of September 30, 2016 and December 31, 2015 consist of the following (in thousands, except weighted-average amortization period): September 30, 2016 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 60 $ 15,017 $ (7,779 ) $ 7,238 Customer lists 47 9,830 (3,192 ) 6,638 Trade names 48 5,243 (1,661 ) 3,582 Non-compete agreements 30 1,720 (1,177 ) 543 Master service agreements 21 1,030 (972 ) 58 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 36,440 $ (14,781 ) $ 21,659 December 31, 2015 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 52 $ 9,417 $ (6,702 ) $ 2,715 Customer lists 20 2,820 (2,239 ) 581 Trade names 48 2,343 (920 ) 1,423 Non-compete agreements 28 1,220 (832 ) 388 Master service agreements 21 1,030 (872 ) 158 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 20,430 $ (11,565 ) $ 8,865
Estimated Future Amortization Expense Related to Intangible Assets	As of September 30, 2016 , the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands): Remaining three months of 2016 $ 1,376 2017 5,153 2018 4,255 2019 3,433 2020 2,153 Thereafter 1,689 Total $ 18,059

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Expense for Employees and Non-Employees	Total share-based compensation expense recorded for employees and non-employees, is as follows (in thousands): Three Months Ended Nine Months Ended 2016 2015 2016 2015 Cost of revenues $ 46 $ 103 $ 115 $ 318 Technology and development 3,449 3,464 11,207 9,444 Sales and marketing 1,605 126 5,456 6,214 General and administrative 5,110 5,240 15,923 15,808 Total share-based compensation expense $ 10,210 $ 8,933 $ 32,701 $ 31,784
Summary of Restricted Stock Unit Activity	RSU and PSU Activity RSUs and PSUs Outstanding Number of RSUs and PSUs Outstanding Weighted Average Grant Date Fair Value Balance at December 31, 2015 13,270,650 $ 6.38 Granted 9,620,354 4.44 Released (4,558,359 ) 6.48 Canceled (3,931,959 ) 6.09 Balance at September 30, 2016 14,400,686 $ 5.13

Restructuring (Credits) Charg27

Restructuring (Credits) Charges (Tables)	9 Months Ended
	Sep. 30, 2016
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Reserve by Type of Cost	The following table summarizes the activity related to the accrual for restructuring charges (in thousands): Workforce Reduction Costs Lease Termination and Other Costs Total Balance at January 1, 2015 $ — $ — $ — Restructuring charges 1,885 2,983 4,868 Cash payments (1,830 ) (675 ) (2,505 ) Write-offs — (317 ) (317 ) Other — 472 472 Balance at December 31, 2015 55 2,463 2,518 Restructuring credits — (298 ) (298 ) Cash payments (55 ) (1,564 ) (1,619 ) Balance at September 30, 2016 $ — $ 601 $ 601

Background and Basis of Prese28

Background and Basis of Presentation (Details)	9 Months Ended
	Sep. 30, 2016segments
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments	1

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator:
Net loss	$ (16,063)	$ (24,167)	$ (40,756)	$ (62,840)
Denominator:
Weighted-average common shares used in computing basic and diluted net loss per share (in shares)	91,059	87,706	90,201	86,419
Net loss per share, basic and diluted (in dollars per share)	$ (0.17)	$ (0.28)	$ (0.45)	$ (0.73)

Net Loss Per Share - Common Sha

Net Loss Per Share - Common Shares Outstanding Excluded From Computation Of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	11,244	8,679	12,914	12,252
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	10,420	8,156	10,917	11,744
RSUs and PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	624	317	1,797	159
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	0	6	0	14
Warrants to purchase common stock | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	200	200	200	335

Cash and Cash Equivalents, In31

Cash and Cash Equivalents, Investments and Restricted Cash - Schedule of Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	$ 90,213	$ 67,030
Net Unrealized Gain/(Loss)	0	(1)
Fair Value	90,213	67,029
Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	0	17,812
Net Unrealized Gain/(Loss)	0	(12)
Fair Value	0	17,800
Long-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	0	4,242
Net Unrealized Gain/(Loss)	0	(13)
Fair Value	0	4,229
Commercial paper | Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	0	3,746
Net Unrealized Gain/(Loss)	0	0
Fair Value	0	3,746
Corporate securities | Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	0	10,572
Net Unrealized Gain/(Loss)	0	(12)
Fair Value	0	10,560
Corporate securities | Long-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	0	3,241
Net Unrealized Gain/(Loss)	0	(10)
Fair Value	0	3,231
Agency bond | Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	0	3,494
Net Unrealized Gain/(Loss)	0	0
Fair Value	0	3,494
Agency bond | Long-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	0	1,001
Net Unrealized Gain/(Loss)	0	(3)
Fair Value	0	998
Cash | Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	88,935	52,905
Net Unrealized Gain/(Loss)	0	0
Fair Value	88,935	52,905
Money market funds | Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	1,278	6,672
Net Unrealized Gain/(Loss)	0	0
Fair Value	1,278	6,672
Commercial paper | Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	0	5,453
Net Unrealized Gain/(Loss)	0	0
Fair Value	0	5,453
Corporate securities | Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	0	600
Net Unrealized Gain/(Loss)	0	(1)
Fair Value	0	599
Agency bond | Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	0	1,400
Net Unrealized Gain/(Loss)	0	0
Fair Value	0	1,400
Short-term restricted cash
Schedule Of Available For Sale Securities [Line Items]
Cost	0	300
Net Unrealized Gain/(Loss)	0	0
Fair Value	0	300
Long-term restricted cash
Schedule Of Available For Sale Securities [Line Items]
Cost	84	478
Net Unrealized Gain/(Loss)	0	0
Fair Value	84	478
Total restricted cash
Schedule Of Available For Sale Securities [Line Items]
Cost	84	778
Net Unrealized Gain/(Loss)	0	0
Fair Value	$ 84	$ 778

Cash and Cash Equivalents, In32

Cash and Cash Equivalents, Investments and Restricted Cash - Contractual Maturity of Available-for-Sale Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of Cost-method Investments [Line Items]
Amortized cost of available-for-sale investments	$ 1,300		$ 1,300
Investments in non-marketable equity investments			1,020	$ 2,019
Equity Investments
Schedule of Cost-method Investments [Line Items]
Investments in non-marketable equity investments	1,000	$ 2,000
Other Assets | Equity Investments
Schedule of Cost-method Investments [Line Items]
Investments	$ 3,000		$ 3,000

Fair Value Measurement (Details

Fair Value Measurement (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Assets:
Short-term investments	$ 0	$ 17,800	[1]
Fair Value on Recurring Basis
Assets:
Total assets measured and recorded at fair value	1,278	36,153
Fair Value on Recurring Basis | Commercial paper
Assets:
Short-term investments		3,746
Fair Value on Recurring Basis | Corporate securities
Assets:
Short-term investments		10,560
Long-term investments		3,231
Fair Value on Recurring Basis | Agency bond
Assets:
Short-term investments		3,494
Long-term investments		998
Fair Value on Recurring Basis | Money market funds
Assets:
Cash equivalents	1,278	6,672
Fair Value on Recurring Basis | Commercial paper
Assets:
Cash equivalents		5,453
Fair Value on Recurring Basis | Corporate securities
Assets:
Cash equivalents		599
Fair Value on Recurring Basis | Agency bond
Assets:
Cash equivalents		1,400
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured and recorded at fair value	1,278	6,672
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial paper
Assets:
Short-term investments		0
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate securities
Assets:
Short-term investments		0
Long-term investments		0
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Agency bond
Assets:
Short-term investments		0
Long-term investments		0
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Assets:
Cash equivalents	1,278	6,672
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial paper
Assets:
Cash equivalents		0
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate securities
Assets:
Cash equivalents		0
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Agency bond
Assets:
Cash equivalents		0
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured and recorded at fair value	0	29,481
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Short-term investments		3,746
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Corporate securities
Assets:
Short-term investments		10,560
Long-term investments		3,231
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Agency bond
Assets:
Short-term investments		3,494
Long-term investments		998
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Money market funds
Assets:
Cash equivalents	$ 0	0
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Cash equivalents		5,453
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Corporate securities
Assets:
Cash equivalents		599
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Agency bond
Assets:
Cash equivalents		$ 1,400
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2015.

Acquisition - Acquisition Detai

Acquisition - Acquisition Details (Details) - Imagine Easy Solutions - USD ($) $ in Thousands	May 01, 2016	Sep. 30, 2016	Sep. 30, 2016
Business Acquisition [Line Items]
Fair value of purchase consideration	$ 42,297
Deferred cash	17,000
Fair value of deferred cash consideration	16,374		$ 16,700
Accretion expense		$ 200	300
Fair value of escrow	4,200
Hold-back	500
Expected payments over next three years	$ 18,000
Contingent consideration arrangement period for recognition	3 years
Contingent consideration liability		$ 2,500	2,500
Acquisition-related expenses			$ 1,000
Achievement Of Performance Conditions
Business Acquisition [Line Items]
Expected payments over next three years	$ 3,000

Acquisition - Acquisition Date

Acquisition - Acquisition Date Fair Value (Details) - Imagine Easy Solutions - USD ($) $ in Thousands	May 01, 2016	Sep. 30, 2016
Business Acquisition [Line Items]
Initial cash consideration	$ 21,023
Net working capital adjustment	200
Fair value of deferred cash consideration	16,374	$ 16,700
Escrow	4,200
Hold-back	500
Fair value of purchase consideration	$ 42,297

Acquisition - Assets Acquired a

Acquisition - Assets Acquired and Liabilities Assumed (Details) - USD ($)	May 01, 2016	Sep. 30, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill		$ 23,679,000	$ 0
Imagine Easy Solutions
Business Acquisition [Line Items]
Cash	$ 59,000
Accounts receivable	2,610,000
Favorable lease acquired	300,000
Other acquired assets	212,000
Acquired intangible assets:	16,010,000
Total identifiable assets acquired	19,191,000
Liabilities assumed	(573,000)
Net identifiable assets acquired	18,618,000
Goodwill	23,679,000
Fair value of purchase consideration	42,297,000
Imagine Easy Solutions | Trade names
Business Acquisition [Line Items]
Acquired intangible assets:	1,800,000
Imagine Easy Solutions | Domain names
Business Acquisition [Line Items]
Acquired intangible assets:	1,100,000
Imagine Easy Solutions | Advertiser relationships
Business Acquisition [Line Items]
Acquired intangible assets:	6,600,000
Imagine Easy Solutions | User base
Business Acquisition [Line Items]
Acquired intangible assets:	410,000
Imagine Easy Solutions | Non-compete agreements
Business Acquisition [Line Items]
Acquired intangible assets:	500,000
Imagine Easy Solutions | Developed technology
Business Acquisition [Line Items]
Acquired intangible assets:	$ 5,600,000

Goodwill and Intangible Asset37

Goodwill and Intangible Assets - Goodwill (Details) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2016		Dec. 31, 2015
Goodwill [Roll Forward]
Beginning balance	$ 91,301,000	[1]	$ 91,301,000
Addition due to acquisition	23,679,000		0
Ending balance	$ 114,980,000		$ 91,301,000	[1]
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2015.

Goodwill and Intangible Asset38

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Finite Lived Intangible Assets [Line Items]
Accumulated Amortization	$ (14,781)		$ (11,565)
Net Carrying Amount	18,059
Indefinite-lived trade name	3,600		3,600
Total intangible assets, gross carrying amount	36,440		20,430
Intangible assets, net	$ 21,659		8,865	[1]
Developed technologies
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	60 months	52 months
Gross Carrying Amount	$ 15,017		9,417
Accumulated Amortization	(7,779)		(6,702)
Net Carrying Amount	$ 7,238		2,715
Customer lists
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	47 months	20 months
Gross Carrying Amount	$ 9,830		2,820
Accumulated Amortization	(3,192)		(2,239)
Net Carrying Amount	$ 6,638		581
Trade names
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	48 months	48 months
Gross Carrying Amount	$ 5,243		2,343
Accumulated Amortization	(1,661)		(920)
Net Carrying Amount	$ 3,582		1,423
Non-compete agreements
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	30 months	28 months
Gross Carrying Amount	$ 1,720		1,220
Accumulated Amortization	(1,177)		(832)
Net Carrying Amount	$ 543		388
Master service agreements
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	21 months	21 months
Gross Carrying Amount	$ 1,030		1,030
Accumulated Amortization	(972)		(872)
Net Carrying Amount	$ 58		$ 158
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2015.

Goodwill and Intangible Asset39

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Acquisition-Related Intangible Assets
Finite Lived Intangible Assets [Line Items]
Amortization expense of acquisition related to acquired intangible assets	$ 1.4	$ 1.1	$ 3.2	$ 4.1

Goodwill and Intangible Asset40

Goodwill and Intangible Assets - Estimated Future Amortization Expense Related to Intangible Assets (Details) $ in Thousands	Sep. 30, 2016USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remaining three months of 2016	$ 1,376
2,017	5,153
2,018	4,255
2,019	3,433
2,020	2,153
Thereafter	1,689
Net Carrying Amount	$ 18,059

Debt Obligations (Details)

Debt Obligations (Details) - Revolving Credit Facility - USD ($)	3 Months Ended	9 Months Ended			12 Months Ended
	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2016	Sep. 30, 2019	Dec. 31, 2015
Debt Instrument [Line Items]
Principal amount				$ 30,000,000
Credit facility, maximum borrowing capacity				50,000,000		$ 65,000,000
EBITDA calculation expense threshold, acquisition expenses				6,000,000
EBITDA calculation expense threshold, nonrecurring expenses				2,000,000
Cash minimum balance				30,000,000
Line of credit facility, current borrowing capacity				$ 30,000,000		$ 30,000,000
Base Interest Rate
Debt Instrument [Line Items]
Marginal interest rate				0.50%
One-Month LIBOR
Debt Instrument [Line Items]
Marginal interest rate				1.00%
LIBOR Rate
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage				0.25%
LIBOR Rate | Maximum
Debt Instrument [Line Items]
Marginal interest rate				4.50%
Total Leverage Ratio Less Than 1.00%
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage				1.50%
Total Leverage Ratio Greater Or Equal 1.00%
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage				2.50%
Scenario, Forecast
Debt Instrument [Line Items]
Cash minimum balance	$ 25,000,000
EBITDA target		$ 30,000,000	$ 25,000,000		$ 35,000,000

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2012	Jul. 31, 2010
Commitments and Contingencies Disclosure [Abstract]
Future sublease income per month (through November 2016)	$ 200		$ 200
Rental expense	$ 500	$ 600	$ 1,400	$ 2,000
Property tax assessment						$ 1,000
Offer to the tax authority excluding tax and penalties					$ 150

Stockholders' Equity - Share-ba

Stockholders' Equity - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 10,210	$ 8,933	$ 32,701	$ 31,784
Cost of revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	46	103	115	318
Technology and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	3,449	3,464	11,207	9,444
Sales and marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	1,605	126	5,456	6,214
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 5,110	$ 5,240	$ 15,923	$ 15,808

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details)	9 Months Ended
	Sep. 30, 2016USD ($)employee$ / sharesshares	Sep. 30, 2015USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized share-based compensation expense | $	$ 0	$ 0
Unrecognized compensation expense for stock options granted to employees, officers, directors, and consultants | $	$ 2,900,000
Restricted Stock Units (RSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards	3 years
Restricted Stock Units (RSUs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards	4 years
Performance-based restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based restricted stock unit award granted to executive officers (shares)		2,300,824
Performance based restricted stock unit award granted weighted average grant date fair value (in dollars per share) | $ / shares		$ 6.59
Released shares	688,464
Performance-based restricted stock units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards	2 years
Performance-based restricted stock units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards	3 years
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average vesting period for recognition of compensation expense	9 months
Restricted Stock Units (RSUs) and Performance Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based restricted stock unit award granted to executive officers (shares)	9,620,354
Performance based restricted stock unit award granted weighted average grant date fair value (in dollars per share) | $ / shares	$ 4.44
Awards forfeited	3,931,959
2015 Performance Period | Performance-based restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees affected | employee	26
Incremental compensation cost | $	$ 1,500,000
2015 Performance Period | Performance-based restricted stock units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards	1 year
2015 Performance Period | Performance-based restricted stock units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards	3 years
2016 Performance Period | Performance-based restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based restricted stock unit award granted to executive officers (shares)	2,377,842
Performance based restricted stock unit award granted weighted average grant date fair value (in dollars per share) | $ / shares	$ 4.32
2016 Performance Period | Performance-based restricted stock units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Final settlement upon achievement of performance conditions, percent	0.00%
2016 Performance Period | Performance-based restricted stock units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Final settlement upon achievement of performance conditions, percent	100.00%
2016 Performance Period | Restricted Stock Units (RSUs) and Performance Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average vesting period for recognition of compensation expense	2 years 18 days
Unrecognized compensation costs related to restricted stock units | $	$ 40,000,000
Vesting occurring March 2017 | 2016 Performance Period | Performance-based restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards	1 year
Vesting occurring March 2018 | 2016 Performance Period | Performance-based restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards	3 years
Employees, Consultants, Officers or Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option awards granted (in shares)	232,700	165,456
Weighted average grant date fair value (in dollars per share) | $ / shares	$ 2.58	$ 3.63

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) and Performance Share Units (PSUs)	9 Months Ended
	Sep. 30, 2016$ / sharesshares
Restricted Stock Units Outstanding
Number of Restricted Stock Units Outstanding, Beginning | shares	13,270,650
Number of RSUs granted (shares) | shares	9,620,354
Number of Restricted Stock Units, Released | shares	(4,558,359)
Number of Restricted Stock Units, Canceled | shares	(3,931,959)
Number of Restricted Stock Units Outstanding, Ending | shares	14,400,686
Weighted-Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Beginning balance | $ / shares	$ 6.38
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	4.44
Weighted Average Grant Date Fair Value, Released | $ / shares	6.48
Weighted Average Grant Date Fair Value, Canceled | $ / shares	6.09
Weighted Average Grant Date Fair Value, Ending balance | $ / shares	$ 5.13

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 554	$ 389	$ 1,463	$ 1,113

Restructuring (Credits) Charg47

Restructuring (Credits) Charges - Restructuring Reserve (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Restructuring Reserve [Roll Forward]
Restructuring Charges	$ (100)	$ 342	$ (298)	$ 3,320
2015 Restructuring Plan
Restructuring Reserve [Roll Forward]
Beginning balance			2,518	0	$ 0
Restructuring Charges					4,868
Cash payments			(1,619)		(2,505)
Write-offs					(317)
Other					472
Restructuring credits			(298)
Ending balance	601		601		2,518
2015 Restructuring Plan | Workforce Reduction Costs
Restructuring Reserve [Roll Forward]
Beginning balance			55	0	0
Restructuring Charges					1,885
Cash payments			(55)		(1,830)
Write-offs					0
Other					0
Restructuring credits			0
Ending balance	0		0		55
2015 Restructuring Plan | Lease Termination and Other Costs
Restructuring Reserve [Roll Forward]
Beginning balance			2,463	$ 0	0
Restructuring Charges					2,983
Cash payments			(1,564)		(675)
Write-offs					(317)
Other					472
Restructuring credits	(198)		(298)
Ending balance	$ 601		$ 601		$ 2,463

Restructuring (Credits) Charg48

Restructuring (Credits) Charges - Narrative (Details) - 2015 Restructuring Plan - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring credits		$ (298)
Restructuring reserve	$ 601	601	$ 2,518	$ 0
Restructuring	500	500
Restructuring reserve, noncurrent	100	100
Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring credits	(198)	(298)
Restructuring reserve	$ 601	$ 601	$ 2,463	$ 0

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)board_member	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Adobe Systems | Chief Executive Officer
Related Party Transaction [Line Items]
Purchases from related party	$ 700,000	$ 1,100,000	$ 2,500,000	$ 2,000,000
Revenue from related parties	0	100,000	0	100,000
Due to related parties	700,000		700,000		$ 400,000
Cengage | Board Of Directors Member
Related Party Transaction [Line Items]
Purchases from related party	2,800,000	2,900,000	7,200,000	9,100,000
Revenue from related parties	600,000	$ 100,000	600,000	$ 1,000,000
Due from related parties	100,000		$ 100,000		$ 0
Number of board members appointed to Board of Directors of related party | board_member			1
Groupon, Inc. | Board Of Directors Member
Related Party Transaction [Line Items]
Purchases from related party	$ 200,000		$ 500,000
Number of board members appointed to Board of Directors of related party | board_member			1