Chegg (CHGG) 10-Q 30 Oct 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 27, 2017
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, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		108,441,709

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	[1]
Current assets
Cash and cash equivalents	$ 122,227	$ 77,329
Short-term investments	80,914	0
Accounts receivable, net of allowance for doubtful accounts of $267 and $436 at September 30, 2017 and December 31, 2016, respectively	9,843	10,451
Prepaid expenses	3,865	2,579
Other current assets	23,955	21,014
Total current assets	240,804	111,373
Long-term investments	17,013	0
Textbook library, net	0	2,575
Property and equipment, net	45,078	35,305
Goodwill	116,239	116,239
Intangible assets, net	16,599	20,748
Other assets	4,419	4,412
Total assets	440,152	290,652
Current liabilities
Accounts payable	2,109	5,175
Deferred revenue	21,906	14,836
Accrued liabilities	41,940	44,319
Total current liabilities	65,955	64,330
Long-term liabilities
Total other long-term liabilities	5,243	4,383
Total liabilities	71,198	68,713
Commitments and contingencies (Note 7)
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; 108,163,229 and 91,708,839 shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively	108	92
Additional paid-in capital	764,097	593,351
Accumulated other comprehensive income (loss)	19	(176)
Accumulated deficit	(395,270)	(371,328)
Total stockholders' equity	368,954	221,939
Total liabilities and stockholders' equity	$ 440,152	$ 290,652
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2016.

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 267	$ 436
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	108,163,229	91,708,839
Common stock, shares outstanding	108,163,229	91,708,839

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net revenues:
Rental	$ 0	$ 5,511	$ 0	$ 32,081
Services	62,640	50,265	181,559	127,812
Sales	0	15,567	0	31,140
Net revenues:	62,640	71,343	181,559	191,033
Cost of revenues:
Rental	0	7,646	0	26,505
Services	22,356	13,203	60,794	39,684
Sales	0	17,850	0	32,840
Cost of revenues:	22,356	38,699	60,794	99,029
Gross profit	40,284	32,644	120,765	92,004
Operating expenses:
Technology and development	19,876	16,241	59,077	49,232
Sales and marketing	14,184	15,256	40,246	41,449
General and administrative	17,320	13,905	47,163	41,140
Restructuring charges (credits)	64	(100)	1,023	(298)
Loss (gain) on liquidation of textbooks	0	2,673	(4,766)	(523)
Total operating expenses	51,444	47,975	142,743	131,000
Loss from operations	(11,160)	(15,331)	(21,978)	(38,996)
Interest expense and other income (expense), net:
Interest expense, net	(19)	(30)	(56)	(151)
Other income (expense), net	261	(148)	53	(146)
Total interest expense and other income (expense), net	242	(178)	(3)	(297)
Loss before provision for income taxes	(10,918)	(15,509)	(21,981)	(39,293)
Provision for income taxes	598	554	1,961	1,463
Net loss	$ (11,516)	$ (16,063)	$ (23,942)	$ (40,756)
Net loss per share, basic and diluted (in dollars per share)	$ (0.11)	$ (0.17)	$ (0.25)	$ (0.45)
Weighted average shares used to compute net loss per share, basic and diluted (in shares)	103,041	91,059	97,008	90,201

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (11,516)	$ (16,063)	$ (23,942)	$ (40,756)
Other comprehensive (loss) income:
Change in unrealized (loss) gain on available for sale investments	(48)	0	(48)	25
Change in foreign currency translation adjustments, net of tax	(9)	35	243	(1)
Other comprehensive (loss) income	(57)	35	195	24
Total comprehensive loss	$ (11,573)	$ (16,028)	$ (23,747)	$ (40,732)

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017		Sep. 30, 2016
Cash flows from operating activities
Net loss	$ (23,942)		$ (40,756)
Adjustments to reconcile net loss to net cash provided by operating activities:
Textbook library depreciation expense	0		8,903
Other depreciation and amortization expense	14,301		10,001
Share-based compensation expense	27,468		32,701
Gain on liquidation of textbooks	(4,766)		(523)
Loss from write-offs of textbooks	314		896
Loss from write-off of property and equipment	1,368		0
Interest accretion on deferred consideration	(626)		0
Other non-cash items	62		106
Change in assets and liabilities, net of acquisition of business:
Accounts receivable	786		312
Prepaid expenses and other current assets	(4,293)		(4,712)
Other assets	(7)		284
Accounts payable	(2,291)		2,713
Deferred revenue	7,070		14,896
Accrued liabilities	12,880		5,997
Other liabilities	1,123		(92)
Net cash provided by operating activities	29,447		30,726
Cash flows from investing activities
Purchases of textbooks	0		(795)
Proceeds from liquidations of textbooks	6,943		23,873
Purchases of marketable securities	(112,417)		(7,633)
Proceeds from sale of marketable securities	14,499		22,830
Maturities of marketable securities	0		6,844
Purchases of property and equipment	(19,930)		(17,834)
Acquisition of business, net of cash acquired	0		(25,864)
Purchase of strategic equity investment	0		(1,020)
Net cash (used in) provided by investing activities	(110,905)		401
Cash flows from financing activities
Common stock issued under stock plans, net	13,565		1,114
Payment of taxes related to the net share settlement of RSUs	(17,902)		(9,057)
Payment of deferred cash consideration related to acquisitions	(16,939)		0
Proceeds from follow-on offering, net of offering costs	147,632		0
Net cash provided by (used in) financing activities	126,356		(7,943)
Net increase in cash and cash equivalents	44,898		23,184
Cash and cash equivalents, beginning of period	77,329	[1]	67,029
Cash and cash equivalents, end of period	122,227		90,213
Supplemental cash flow data:
Interest	66		47
Income taxes	1,241		831
Non-cash investing and financing activities:
Accrued purchases of long-lived assets	$ 3,712		$ 1,517
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2016.

Background and Basis of Present

Background and Basis of Presentation	9 Months Ended
	Sep. 30, 2017
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 in July 2005. Chegg is the leading student-first connected learning platform. Our goal is to help students transition from high school to college to career, with a view to improving student outcomes. We help students study more effectively for college admission 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 student-first connected learning platform offers products and services that help students transition from high school to college to career. Basis of Presentation The accompanying condensed consolidated balance sheet as of September 30, 2017 , the condensed consolidated statements of operations and the condensed consolidated statements of comprehensive (loss) income for the three and nine months ended September 30, 2017 and 2016 , the condensed consolidated statements of cash flows for the nine months ended September 30, 2017 and 2016 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, 2017 and our results of operations for the three and nine months ended September 30, 2017 and 2016 , and cash flows for the nine months ended September 30, 2017 and 2016 . Our results of operations for the three and nine months ended September 30, 2017 and cash flows for the nine months ended September 30, 2017 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, 2016 as 2016 . 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 that are included in our Annual Report on Form 10-K for the year ended December 31, 2016 (2016 Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). Except for our textbook library, there have been no material changes to our significant accounting policies as compared to the significant accounting policies described in our 2016 Annual Report on Form 10-K. We no longer consider our textbook library to be a significant accounting policy as we no longer have a balance as of March 31, 2017. Reclassification of Prior Period Presentation In order to conform with current period presentation, $0.5 million and $1.0 million of sales revenues during the three and nine months ended September 30, 2016 , respectively, have been reclassified to services revenues and $0.3 million and $1.0 million of sales cost of revenues during the three and nine months ended September 30, 2016 , respectively, have been reclassified to services cost of revenues on our condensed consolidated statements of operations. Additionally, we have reclassified $1.2 million from other current assets to accounts receivable on our condensed consolidated balance sheet as of December 31, 2016. These changes in presentation do not affect previously reported results. 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, 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 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 following accounting pronouncements, there have been no material changes to recent accounting pronouncements as compared to recent accounting pronouncements described in our 2016 Annual Report on Form 10-K. In May 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-09 Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting . ASU 2017-09 clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. The guidance is effective for annual periods after December 15, 2017, with early adoption permitted, and the guidance requires a prospective application to awards modified on or after the adoption date. We have elected to early adopt this standard as of July 1, 2017 and will account for any modifications after this date under the new guidance. In January 2017, the FASB issued ASU No. 2017-04 Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment . ASU 2017-04 eliminates step 2 from the annual goodwill impairment test no longer requiring the comparison of the implied fair value of a reporting unit's goodwill with the carrying amount of goodwill. Early adoption is permitted and the guidance requires a prospective application. The guidance is effective for annual periods after December 15, 2019, and we are currently in the process of evaluating the impact of this guidance. In January 2017, the FASB issued ASU No. 2017-01 Business Combinations (Topic 805): Clarifying the Definition of a Business . ASU 2017-01 clarifies the definition of a business to assist entities with evaluating whether a transaction should be accounted for as acquisitions of assets or businesses. Early adoption is permitted and the guidance requires a prospective application. The guidance is effective for annual periods after December 15, 2017, and we are currently in the process of evaluating the impact of this guidance. In March 2016, the FASB issued ASU No. 2016-09 Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting to provide for simplification involving several aspects of the accounting for share-based payment transactions. The new standard requires excess tax benefits and tax deficiencies to be recorded in our consolidated statements of operations as a component of provision for income taxes when stock awards vest or are settled and an option to recognize gross share-based compensation expense with actual forfeitures recognized as they occur. In addition, it eliminates the requirement to reclassify cash flows related to excess tax benefits from operating activities to financing activities on the consolidated statements of cash flows and clarifies that all cash payments made to tax authorities on an employee’s behalf for withheld shares should be presented as a financing activity on the consolidated statements of cash flows. The standard also allows us to withhold more of an employee’s vesting shares for tax withholding purposes without triggering liability accounting. We adopted this standard in the first quarter of 2017 and the adoption had no impact to our consolidated financial statements. The requirement to record excess tax benefits and deficiencies in our consolidated statements of operations as a component of provision of income taxes when stock awards vest or are settled does not impact our provision of income taxes as we currently have a full valuation allowance recorded against our deferred tax assets related to share-based compensation. Additionally, we have elected to continue to recognize share-based compensation expense net of estimated forfeitures. We have not recorded an adjustment to retained earnings to reflect the modified retrospective adoption of this standard update as neither of these updates change the accounting of the prior period financial results. We have elected to adopt the elimination of the requirement to reclassify cash flows related to excess tax benefits from operating activities to financing activities on the condensed consolidated statements of cash flows prospectively and therefore prior periods have not been adjusted. Further, there was no change related to the requirement that all payments made to tax authorities on an employees' behalf for withheld shares be presented as a financing activity on the consolidated statements of cash flows as we have always recorded such amounts as a financing activity. 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 plan to adopt the guidance starting in the first quarter of 2019. We are currently in the process of evaluating the impact of this guidance. In May 2014, the FASB issued ASU No. 2014-09 Revenue from Contracts with Customers, as amended (Topic 606) (ASU 2014-09), which will change the way we recognize revenue and significantly expand the disclosure requirements for revenue arrangements. In July 2015, the FASB approved a one-year deferral of the effective date of ASU 2014-09 for public companies and further amendments and technical corrections were made to ASU 2014-09 during 2016. ASU 2014-09 allows 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). We plan to adopt ASU 2014-09 under the modified retrospective application. ASU 2014-09 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 ASU 2014-09 starting on January 1, 2018. We are currently in the process of evaluating the impact ASU 2014-09 may have on our consolidated financial statements, accounting policies, and related disclosures. We believe that we will continue to operate as an agent in our strategic partnership with Ingram and agreements with other textbook publishers under the new guidance and therefore continue to recognize a commission on print textbook rental transactions. We have initially determined three potential areas of impact which are subject to further evaluation. First, the timing of revenue recognition relating to our Enrollment Marketing and Brand Partnership product offerings is anticipated to be recognized earlier in the contract life under ASU 2014-09 than under the current guidance. Second, we will estimate and account for the variable consideration earned relating to our performance related obligation with Ingram over the period in which it is earned under ASU 2014-09 as opposed to at the completion of the period under the current guidance. Finally, revenues previously recognized from shipping and handling activities will be recognized as a reduction of cost of revenues under ASU 2014-09 as these activities do not represent a separately identifiable performance obligation. These are the significant areas that we have identified will be different under ASU 2014-09 and we will continue to evaluate ASU 2014-09 as we near our adoption date.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2017
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. 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 2017 2016 2017 2016 Numerator: Net loss $ (11,516 ) $ (16,063 ) $ (23,942 ) $ (40,756 ) Denominator: Weighted average shares used to compute net loss per share, basic and diluted 103,041 91,059 97,008 90,201 Net loss per share, basic and diluted $ (0.11 ) $ (0.17 ) $ (0.25 ) $ (0.45 ) 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 2017 2016 2017 2016 Options to purchase common stock 2 10,420 3,167 10,917 RSUs and PSUs 49 624 137 1,797 Warrants to purchase common stock — 200 200 200 Total common stock equivalents 51 11,244 3,504 12,914

Cash and Cash Equivalents, and

Cash and Cash Equivalents, and Investments	9 Months Ended
	Sep. 30, 2017
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents, and Investments	Cash and Cash Equivalents, 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, 2017 (in thousands): September 30, 2017 Cost Net Unrealized Gain/(Loss) Fair Value Cash and cash equivalents: Cash $ 90,256 $ — $ 90,256 Money market funds 11,036 — 11,036 Commercial paper 20,933 2 20,935 Total cash and cash equivalents $ 122,225 $ 2 $ 122,227 Short-term investments: Commercial paper $ 41,975 $ (4 ) $ 41,971 Corporate securities 18,998 (11 ) 18,987 U.S. treasury securities 19,963 (7 ) 19,956 Total short-term investments $ 80,936 $ (22 ) $ 80,914 Long-term corporate securities $ 17,041 $ (28 ) $ 17,013 The adjusted cost and fair value of available-for-sale investments as of September 30, 2017 by contractual maturity were as follows (in thousands): Cost Fair Value Due in 1 year or less $ 101,869 $ 101,849 Due in 1-2 years 17,041 17,013 Investments not due at a single maturity date 11,036 11,036 Total $ 129,946 $ 129,898 Investments not due at a single maturity date in the preceding table consist of money market fund deposits. As of September 30, 2017 , we considered the declines in market value of our investment portfolio to be temporary in nature and did not consider any of our investments to be other-than-temporarily impaired. We typically invest in highly-rated securities with a minimum credit rating of A- and a weighted average maturity of seven months, and 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, the investment before recovery of the investment’s cost basis. During the nine months ended September 30, 2017 , we did not recognize any impairment charges. As of December 31, 2016 , we did not carry a balance of cash equivalents, short-term or long-term investments. Restricted Cash As of September 30, 2017 and December 31, 2016 , we had approximately $0.4 million and $0.1 million , respectively, of restricted cash that consists of security deposits for our offices. These amounts are classified in other assets in our condensed consolidated balance sheets as these amounts are restricted for periods that exceed one year from the balance sheet dates. Strategic Investment We previously invested $3.0 million in a foreign entity to explore expanding our reach internationally. Our investment is included in other assets on our condensed consolidated balance sheets. We did not record other-than-temporary impairment charges on this investment during the three and nine months ended September 30, 2017 and 2016 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, 2017
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. 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, 2017 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2017 Total Quoted Prices Significant Cash equivalents: Money market funds $ 11,036 $ 11,036 $ — Commercial paper 20,935 — 20,935 Short-term investments: Commercial paper 41,971 — 41,971 Corporate securities 18,987 — 18,987 U.S. treasury securities 19,956 — 19,956 Long-term corporate securities 17,013 — 17,013 Total assets measured and recorded at fair value $ 129,898 $ 11,036 $ 118,862 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.

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2017
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	Intangible Assets Intangible assets as of September 30, 2017 and December 31, 2016 consist of the following (in thousands, except the weighted-average amortization period): September 30, 2017 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 60 $ 15,077 $ (9,616 ) $ 5,461 Customer lists 47 9,970 (5,138 ) 4,832 Trade names 47 5,513 (3,077 ) 2,436 Non-compete agreements 30 1,728 (1,458 ) 270 Master service agreements 21 1,030 (1,030 ) — Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 36,918 $ (20,319 ) $ 16,599 December 31, 2016 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 60 $ 15,077 $ (8,245 ) $ 6,832 Customer lists 47 9,970 (3,673 ) 6,297 Trade names 47 5,513 (1,998 ) 3,515 Non-compete agreements 30 1,728 (1,249 ) 479 Master service agreements 21 1,030 (1,005 ) 25 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 36,918 $ (16,170 ) $ 20,748 During the three and nine months ended September 30, 2017 , amortization expense related to our acquired intangible assets totaled approximately $1.4 million and $4.1 million , respectively. 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. As of September 30, 2017 , the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands): Remaining three months of 2017 $ 1,201 2018 4,446 2019 3,510 2020 2,153 2021 815 Thereafter 874 Total $ 12,999

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2017
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 replaced 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), plus depreciation expense, plus 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 lender 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 September 30, 2017 , 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, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We lease our offices under operating leases, which expire at various dates through 2022. Our primary operating lease commitments at September 30, 2017 are related to our headquarters in Santa Clara, California, our office in San Francisco, California, and our office in India. 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. Rental expense, net of sublease income, was approximately $0.6 million and $2.0 million during the three and nine months ended September 30, 2017 , respectively, and $0.5 million and $1.4 million during the three and nine months ended September 30, 2016 , 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. 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, 2017
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, 2017 .

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholders' Equity	Stockholders' Equity Follow-on Offering On August 8, 2017, we closed an underwritten public offering pursuant to a registration statement on Form S-3 of 11,500,000 shares of our common stock sold by us, including 1,500,000 shares sold upon full exercise of the underwriters’ option to purchase additional shares of common stock, at a price to the public of $13.50 per share, generating aggregate net proceeds of $147.6 million , after deducting underwriting discounts and commissions of $7.0 million and offering costs of $0.6 million . Share-based Compensation Expense Total share-based compensation expense recorded for employees and non-employees is as follows (in thousands): Three Months Ended Nine Months Ended 2017 2016 2017 2016 Cost of revenues $ 73 $ 46 $ 228 $ 115 Technology and development 3,706 3,449 10,334 11,207 Sales and marketing 1,261 1,605 3,588 5,456 General and administrative 5,051 5,110 13,318 15,923 Total share-based compensation expense $ 10,091 $ 10,210 $ 27,468 $ 32,701 There was no capitalized share-based compensation expense as of September 30, 2017 or 2016 . Stock Option Activity There were no stock option awards granted to employees, consultants, officers or directors during the nine months ended September 30, 2017 . During the nine months ended September 30, 2016 , we granted 232,700 stock option awards at a weighted-average grant date fair value of $2.58 solely to members of our board of directors. As of September 30, 2017 , our total unrecognized share-based compensation expense related to stock option awards was approximately $0.2 million , which will be recognized over the remaining weighted-average vesting period of approximately 0.8 years . RSU and PSU Activity Activity for RSUs and PSUs is as follows: RSUs and PSUs Outstanding Number of RSUs and PSUs Outstanding Weighted-Average Grant Date Fair Value Balance at December 31, 2016 14,142,109 $ 5.20 Granted 6,425,919 8.75 Released (4,968,509 ) 5.67 Canceled (1,153,704 ) 6.01 Balance at September 30, 2017 14,445,815 $ 6.57 As of September 30, 2017 , our total unrecognized share-based compensation expense related to RSUs and PSUs was approximately $55.7 million , which will be recognized over the remaining weighted-average vesting period of approximately 1.9 years .

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We recorded an income tax provision of approximately $0.6 million and $2.0 million during the three and nine months ended September 30, 2017 , respectively, and an income tax provision of approximately $0.6 million and $1.5 million for the three and nine months ended September 30, 2016 , respectively, primarily due to state and foreign income tax expense and federal tax expense related to tax amortization of acquired indefinite lived intangible assets.

Restructuring Charges (Credits)

Restructuring Charges (Credits)	9 Months Ended
	Sep. 30, 2017
Restructuring and Related Activities [Abstract]
Restructuring Charges (Credits)	Restructuring Charges (Credits) 2017 Restructuring Plan In January 2017, we entered into a strategic partnership with the National Research Center for College & University Admissions (NRCCUA) where NRCCUA will assume responsibility for managing, renewing, and maintaining our existing university contracts and become the exclusive reseller of our digital enrollment marketing services for colleges and universities. As a result of this strategic partnership, approximately 50 employees in China and the United States supporting the sales and account support functions of our Enrollment Marketing offering were terminated, resulting in one-time workforce reduction costs of $0.9 million and lease termination and other costs of $0.1 million recorded during the nine months ended September 30, 2017 . We expect costs incurred to date related to this workforce reduction to be fully paid within six months. 2015 Restructuring Plan Restructuring credits recorded in 2016 of $0.4 million primarily related to a partial reversal of previously accrued lease termination costs due to our subtenant leasing additional space in our Kentucky warehouse. Costs incurred to date related to the lease termination and other costs are expected to be fully paid by 2021. The following table summarizes the activity related to the accrual for restructuring charges (credits) (in thousands): 2017 Restructuring Plan 2015 Restructuring Plan Workforce Reduction Costs Lease Termination and Other Costs Workforce Reduction Costs Lease Termination and Other Costs Total Balance at January 1, 2016 $ — $ — $ 55 $ 2,463 $ 2,518 Restructuring credits — — — (423 ) (423 ) Cash payments — — (55 ) (1,734 ) (1,789 ) Balance at December 31, 2016 — — — 306 306 Restructuring charges (credits) 927 138 — (42 ) 1,023 Cash payments (897 ) (118 ) — (14 ) (1,029 ) Write-offs — (20 ) — — (20 ) Balance at September 30, 2017 $ 30 $ — $ — $ 250 $ 280 As of September 30, 2017 , the $0.3 million liability was comprised of a short-term accrual of $0.1 million included within accrued liabilities and a long-term accrual of $0.2 million included within other liabilities on our condensed consolidated balance sheets.

Related-Party Transactions

Related-Party Transactions	9 Months Ended
	Sep. 30, 2017
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, 2017 , we had purchases of $0.8 million and $2.6 million , respectively, and during the three and nine months ended September 30, 2016 , we had purchases of $0.7 million and $2.5 million , respectively, from Adobe. We had no revenues in the three and nine months ended September 30, 2017 and September 30, 2016 , respectively, from Adobe. We had an immaterial amount and $0.3 million in payables as of September 30, 2017 and December 31, 2016 , respectively, to Adobe. We had no outstanding accounts receivables as of September 30, 2017 and December 31, 2016 , 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, 2017 , we had purchases of $4.7 million and $9.5 million , respectively, and during the three and nine months ended September 30, 2016 , we had purchases of $2.8 million and $7.2 million , respectively, from Cengage. We had $1.2 million and $1.8 million of revenues in the three and nine months ended September 30, 2017 , respectively, and $0.6 million in revenues in both the three and nine months ended September 30, 2016 from Cengage. We had an immaterial amount in payables as of September 30, 2017 and December 31, 2016 to Cengage. We had $0.3 million and $0.1 million in outstanding accounts receivables as of September 30, 2017 and December 31, 2016 , respectively, 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, 2017 , we had purchases of $0.2 million and $0.5 million , respectively, and during the three and nine months ended September 30, 2016 , we had purchases of $0.2 million and $0.5 million , respectively, from Groupon. We had no revenues in the three and nine months ended September 30, 2017 and September 30, 2016 , respectively, from Groupon. We had no payables as of September 30, 2017 and an immaterial amount in payables as of December 31, 2016 to Groupon. We had no outstanding accounts receivables as of September 30, 2017 and December 31, 2016 from Groupon. The immediate family of one of our board members is also a member of the Board of Directors of PayPal Holdings, Inc. (PayPal). During the three and nine months ended September 30, 2017 , we incurred payment processing fees of $0.3 million and $0.8 million , respectively, to PayPal.

Subsequent Event Subsequent Eve

Subsequent Event Subsequent Event	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Event	Subsequent Events Acquisition of Cogeon GmbH On October 16, 2017 , we acquired all of the outstanding interest of Cogeon GmbH (Cogeon) , a privately held online learning company based in Berlin, Germany that provides adaptive math technology . Pursuant to the terms of the share purchase agreement, we paid €12.5 million (approximately $15.0 million ) in cash to the sellers at the closing of the acquisition. There are potential payments of up to €7.5 million (approximately $9.0 million ) over the next three years subject to certain contingencies. These contingent payments may be settled by us, in our sole discretion, either in cash or shares of our common stock. Additionally, there are potential issuances of up to €3.2 million (approximately $3.8 million ) in RSUs over the next three years subject to certain contingencies. The potential contingent payments and RSU issuances equivalent value in USD may fluctuate based on the exchange rate at the time the payment or issuance is made.

Background and Basis of Prese20

Background and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated balance sheet as of September 30, 2017 , the condensed consolidated statements of operations and the condensed consolidated statements of comprehensive (loss) income for the three and nine months ended September 30, 2017 and 2016 , the condensed consolidated statements of cash flows for the nine months ended September 30, 2017 and 2016 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, 2017 and our results of operations for the three and nine months ended September 30, 2017 and 2016 , and cash flows for the nine months ended September 30, 2017 and 2016 . Our results of operations for the three and nine months ended September 30, 2017 and cash flows for the nine months ended September 30, 2017 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, 2016 as 2016 . 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 that are included in our Annual Report on Form 10-K for the year ended December 31, 2016 (2016 Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). Except for our textbook library, there have been no material changes to our significant accounting policies as compared to the significant accounting policies described in our 2016 Annual Report on Form 10-K.
Reclassification of Prior Period Presentation	Reclassification of Prior Period Presentation In order to conform with current period presentation, $0.5 million and $1.0 million of sales revenues during the three and nine months ended September 30, 2016 , respectively, have been reclassified to services revenues and $0.3 million and $1.0 million of sales cost of revenues during the three and nine months ended September 30, 2016 , respectively, have been reclassified to services cost of revenues on our condensed consolidated statements of operations.
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, 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 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 following accounting pronouncements, there have been no material changes to recent accounting pronouncements as compared to recent accounting pronouncements described in our 2016 Annual Report on Form 10-K. In May 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-09 Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting . ASU 2017-09 clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. The guidance is effective for annual periods after December 15, 2017, with early adoption permitted, and the guidance requires a prospective application to awards modified on or after the adoption date. We have elected to early adopt this standard as of July 1, 2017 and will account for any modifications after this date under the new guidance. In January 2017, the FASB issued ASU No. 2017-04 Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment . ASU 2017-04 eliminates step 2 from the annual goodwill impairment test no longer requiring the comparison of the implied fair value of a reporting unit's goodwill with the carrying amount of goodwill. Early adoption is permitted and the guidance requires a prospective application. The guidance is effective for annual periods after December 15, 2019, and we are currently in the process of evaluating the impact of this guidance. In January 2017, the FASB issued ASU No. 2017-01 Business Combinations (Topic 805): Clarifying the Definition of a Business . ASU 2017-01 clarifies the definition of a business to assist entities with evaluating whether a transaction should be accounted for as acquisitions of assets or businesses. Early adoption is permitted and the guidance requires a prospective application. The guidance is effective for annual periods after December 15, 2017, and we are currently in the process of evaluating the impact of this guidance. In March 2016, the FASB issued ASU No. 2016-09 Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting to provide for simplification involving several aspects of the accounting for share-based payment transactions. The new standard requires excess tax benefits and tax deficiencies to be recorded in our consolidated statements of operations as a component of provision for income taxes when stock awards vest or are settled and an option to recognize gross share-based compensation expense with actual forfeitures recognized as they occur. In addition, it eliminates the requirement to reclassify cash flows related to excess tax benefits from operating activities to financing activities on the consolidated statements of cash flows and clarifies that all cash payments made to tax authorities on an employee’s behalf for withheld shares should be presented as a financing activity on the consolidated statements of cash flows. The standard also allows us to withhold more of an employee’s vesting shares for tax withholding purposes without triggering liability accounting. We adopted this standard in the first quarter of 2017 and the adoption had no impact to our consolidated financial statements. The requirement to record excess tax benefits and deficiencies in our consolidated statements of operations as a component of provision of income taxes when stock awards vest or are settled does not impact our provision of income taxes as we currently have a full valuation allowance recorded against our deferred tax assets related to share-based compensation. Additionally, we have elected to continue to recognize share-based compensation expense net of estimated forfeitures. We have not recorded an adjustment to retained earnings to reflect the modified retrospective adoption of this standard update as neither of these updates change the accounting of the prior period financial results. We have elected to adopt the elimination of the requirement to reclassify cash flows related to excess tax benefits from operating activities to financing activities on the condensed consolidated statements of cash flows prospectively and therefore prior periods have not been adjusted. Further, there was no change related to the requirement that all payments made to tax authorities on an employees' behalf for withheld shares be presented as a financing activity on the consolidated statements of cash flows as we have always recorded such amounts as a financing activity. 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 plan to adopt the guidance starting in the first quarter of 2019. We are currently in the process of evaluating the impact of this guidance. In May 2014, the FASB issued ASU No. 2014-09 Revenue from Contracts with Customers, as amended (Topic 606) (ASU 2014-09), which will change the way we recognize revenue and significantly expand the disclosure requirements for revenue arrangements. In July 2015, the FASB approved a one-year deferral of the effective date of ASU 2014-09 for public companies and further amendments and technical corrections were made to ASU 2014-09 during 2016. ASU 2014-09 allows 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). We plan to adopt ASU 2014-09 under the modified retrospective application. ASU 2014-09 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 ASU 2014-09 starting on January 1, 2018. We are currently in the process of evaluating the impact ASU 2014-09 may have on our consolidated financial statements, accounting policies, and related disclosures. We believe that we will continue to operate as an agent in our strategic partnership with Ingram and agreements with other textbook publishers under the new guidance and therefore continue to recognize a commission on print textbook rental transactions. We have initially determined three potential areas of impact which are subject to further evaluation. First, the timing of revenue recognition relating to our Enrollment Marketing and Brand Partnership product offerings is anticipated to be recognized earlier in the contract life under ASU 2014-09 than under the current guidance. Second, we will estimate and account for the variable consideration earned relating to our performance related obligation with Ingram over the period in which it is earned under ASU 2014-09 as opposed to at the completion of the period under the current guidance. Finally, revenues previously recognized from shipping and handling activities will be recognized as a reduction of cost of revenues under ASU 2014-09 as these activities do not represent a separately identifiable performance obligation. These are the significant areas that we have identified will be different under ASU 2014-09 and we will continue to evaluate ASU 2014-09 as we near our adoption date.
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. 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 (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2017
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 2017 2016 2017 2016 Numerator: Net loss $ (11,516 ) $ (16,063 ) $ (23,942 ) $ (40,756 ) Denominator: Weighted average shares used to compute net loss per share, basic and diluted 103,041 91,059 97,008 90,201 Net loss per share, basic and diluted $ (0.11 ) $ (0.17 ) $ (0.25 ) $ (0.45 )
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 2017 2016 2017 2016 Options to purchase common stock 2 10,420 3,167 10,917 RSUs and PSUs 49 624 137 1,797 Warrants to purchase common stock — 200 200 200 Total common stock equivalents 51 11,244 3,504 12,914

Cash and Cash Equivalents, an22

Cash and Cash Equivalents, and Investments (Tables)	9 Months Ended
	Sep. 30, 2017
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents 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, 2017 (in thousands): September 30, 2017 Cost Net Unrealized Gain/(Loss) Fair Value Cash and cash equivalents: Cash $ 90,256 $ — $ 90,256 Money market funds 11,036 — 11,036 Commercial paper 20,933 2 20,935 Total cash and cash equivalents $ 122,225 $ 2 $ 122,227 Short-term investments: Commercial paper $ 41,975 $ (4 ) $ 41,971 Corporate securities 18,998 (11 ) 18,987 U.S. treasury securities 19,963 (7 ) 19,956 Total short-term investments $ 80,936 $ (22 ) $ 80,914 Long-term corporate securities $ 17,041 $ (28 ) $ 17,013
Schedule of Available-for-sale Securities Reconciliation	The adjusted cost and fair value of available-for-sale investments as of September 30, 2017 by contractual maturity were as follows (in thousands): Cost Fair Value Due in 1 year or less $ 101,869 $ 101,849 Due in 1-2 years 17,041 17,013 Investments not due at a single maturity date 11,036 11,036 Total $ 129,946 $ 129,898

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Financial instruments measured and recorded at fair value on a recurring basis as of September 30, 2017 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2017 Total Quoted Prices Significant Cash equivalents: Money market funds $ 11,036 $ 11,036 $ — Commercial paper 20,935 — 20,935 Short-term investments: Commercial paper 41,971 — 41,971 Corporate securities 18,987 — 18,987 U.S. treasury securities 19,956 — 19,956 Long-term corporate securities 17,013 — 17,013 Total assets measured and recorded at fair value $ 129,898 $ 11,036 $ 118,862

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2017
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Schedule of Acquired Indefinite-lived Intangible Assets by Major Class	Intangible assets as of September 30, 2017 and December 31, 2016 consist of the following (in thousands, except the weighted-average amortization period): September 30, 2017 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 60 $ 15,077 $ (9,616 ) $ 5,461 Customer lists 47 9,970 (5,138 ) 4,832 Trade names 47 5,513 (3,077 ) 2,436 Non-compete agreements 30 1,728 (1,458 ) 270 Master service agreements 21 1,030 (1,030 ) — Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 36,918 $ (20,319 ) $ 16,599 December 31, 2016 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 60 $ 15,077 $ (8,245 ) $ 6,832 Customer lists 47 9,970 (3,673 ) 6,297 Trade names 47 5,513 (1,998 ) 3,515 Non-compete agreements 30 1,728 (1,249 ) 479 Master service agreements 21 1,030 (1,005 ) 25 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 36,918 $ (16,170 ) $ 20,748
Schedule of Acquired Finite-lived Intangible Assets by Major Class	Intangible assets as of September 30, 2017 and December 31, 2016 consist of the following (in thousands, except the weighted-average amortization period): September 30, 2017 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 60 $ 15,077 $ (9,616 ) $ 5,461 Customer lists 47 9,970 (5,138 ) 4,832 Trade names 47 5,513 (3,077 ) 2,436 Non-compete agreements 30 1,728 (1,458 ) 270 Master service agreements 21 1,030 (1,030 ) — Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 36,918 $ (20,319 ) $ 16,599 December 31, 2016 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 60 $ 15,077 $ (8,245 ) $ 6,832 Customer lists 47 9,970 (3,673 ) 6,297 Trade names 47 5,513 (1,998 ) 3,515 Non-compete agreements 30 1,728 (1,249 ) 479 Master service agreements 21 1,030 (1,005 ) 25 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 36,918 $ (16,170 ) $ 20,748
Estimated Future Amortization Expense Related to Intangible Assets	As of September 30, 2017 , the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands): Remaining three months of 2017 $ 1,201 2018 4,446 2019 3,510 2020 2,153 2021 815 Thereafter 874 Total $ 12,999

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2017
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 2017 2016 2017 2016 Cost of revenues $ 73 $ 46 $ 228 $ 115 Technology and development 3,706 3,449 10,334 11,207 Sales and marketing 1,261 1,605 3,588 5,456 General and administrative 5,051 5,110 13,318 15,923 Total share-based compensation expense $ 10,091 $ 10,210 $ 27,468 $ 32,701
Summary of Restricted Stock Unit Activity	Activity for RSUs and PSUs is as follows: RSUs and PSUs Outstanding Number of RSUs and PSUs Outstanding Weighted-Average Grant Date Fair Value Balance at December 31, 2016 14,142,109 $ 5.20 Granted 6,425,919 8.75 Released (4,968,509 ) 5.67 Canceled (1,153,704 ) 6.01 Balance at September 30, 2017 14,445,815 $ 6.57

Restructuring Charges (Credit26

Restructuring Charges (Credits) (Tables)	9 Months Ended
	Sep. 30, 2017
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 (credits) (in thousands): 2017 Restructuring Plan 2015 Restructuring Plan Workforce Reduction Costs Lease Termination and Other Costs Workforce Reduction Costs Lease Termination and Other Costs Total Balance at January 1, 2016 $ — $ — $ 55 $ 2,463 $ 2,518 Restructuring credits — — — (423 ) (423 ) Cash payments — — (55 ) (1,734 ) (1,789 ) Balance at December 31, 2016 — — — 306 306 Restructuring charges (credits) 927 138 — (42 ) 1,023 Cash payments (897 ) (118 ) — (14 ) (1,029 ) Write-offs — (20 ) — — (20 ) Balance at September 30, 2017 $ 30 $ — $ — $ 250 $ 280

Background and Basis of Prese27

Background and Basis of Presentation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales revenues	$ 0	$ 15,567	$ 0	$ 31,140
Sales cost of revenues	0	17,850	0	32,840
Services revenues	62,640	50,265	181,559	127,812
Services cost of revenues	22,356	13,203	60,794	39,684
Other current assets	(23,955)		(23,955)		$ (21,014)	[1]
Accounts receivable	$ 9,843		$ 9,843		10,451	[1]
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales revenues		(100)		(500)
Sales cost of revenues		(300)		(700)
Services revenues		500		1,000
Services cost of revenues		$ 300		$ 1,000
Other current assets					1,200
Accounts receivable					$ 1,200
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2016.

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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net loss	$ (11,516)	$ (16,063)	$ (23,942)	$ (40,756)
Denominator:
Weighted average shares used to compute net loss per share, basic and diluted (in shares)	103,041	91,059	97,008	90,201
Net loss per share, basic and diluted (in dollars per share)	$ (0.11)	$ (0.17)	$ (0.25)	$ (0.45)

Net Loss Per Share - Shares Exc

Net Loss Per Share - Shares Excluded From Computation Of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	51	11,244	3,504	12,914
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	2	10,420	3,167	10,917
RSUs and PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	49	624	137	1,797
Warrants to purchase common stock | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	0	200	200	200

Cash and Cash Equivalents, an30

Cash and Cash Equivalents, and Investments - Schedule of Investments (Details) $ in Thousands	Sep. 30, 2017USD ($)
Cash and cash equivalents:
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 122,225
Net Unrealized Gain/(Loss)	2
Fair Value	122,227
Short-term investments:
Schedule of Available-for-sale Securities [Line Items]
Cost	80,936
Net Unrealized Gain/(Loss)	(22)
Fair Value	80,914
Long-term investments:
Schedule of Available-for-sale Securities [Line Items]
Cost	17,041
Net Unrealized Gain/(Loss)	(28)
Fair Value	17,013
Commercial paper | Short-term investments:
Schedule of Available-for-sale Securities [Line Items]
Cost	41,975
Net Unrealized Gain/(Loss)	(4)
Fair Value	41,971
Corporate securities | Short-term investments:
Schedule of Available-for-sale Securities [Line Items]
Cost	18,998
Net Unrealized Gain/(Loss)	(11)
Fair Value	18,987
U.S. treasury securities | Short-term investments:
Schedule of Available-for-sale Securities [Line Items]
Cost	19,963
Net Unrealized Gain/(Loss)	(7)
Fair Value	19,956
Cash | Cash and cash equivalents:
Schedule of Available-for-sale Securities [Line Items]
Cost	90,256
Net Unrealized Gain/(Loss)	0
Fair Value	90,256
Money market funds | Cash and cash equivalents:
Schedule of Available-for-sale Securities [Line Items]
Cost	11,036
Net Unrealized Gain/(Loss)	0
Fair Value	11,036
Commercial paper | Cash and cash equivalents:
Schedule of Available-for-sale Securities [Line Items]
Cost	20,933
Net Unrealized Gain/(Loss)	2
Fair Value	$ 20,935

Cash and Cash Equivalents, an31

Cash and Cash Equivalents, and Investments - Contractual Maturity (Details) $ in Thousands	Sep. 30, 2017USD ($)
Cash and Cash Equivalents [Abstract]
Due in 1 year or less, cost	$ 101,869
Due in 1-2 years, cost	17,041
Investments not due at a single maturity date, cost	11,036
Total, cost	129,946
Due in 1 year or less, fair value	101,849
Due in 1-2 years, fair value	17,013
Investments not due at a single maturity date, fair value	11,036
Total, fair value	$ 129,898

Cash and Cash Equivalents, an32

Cash and Cash Equivalents, and Investments - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Schedule of Cost-method Investments [Line Items]
Weighted average maturity	7 months
Restricted cash	$ 0.4	$ 0.1
Other Assets | Equity Investments
Schedule of Cost-method Investments [Line Items]
Investments	$ 3

Fair Value Measurement (Details

Fair Value Measurement (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	[1]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term Investments	$ 80,914	$ 0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	129,898
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	11,036
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	118,862
Money market funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	11,036
Money market funds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	11,036
Money market funds | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0
Commercial paper | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	20,935
Short-term Investments	41,971
Commercial paper | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0
Short-term Investments	0
Commercial paper | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	20,935
Short-term Investments	41,971
U.S. treasury securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term Investments	19,956
U.S. treasury securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term Investments	0
U.S. treasury securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term Investments	19,956
Corporate securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term Investments	18,987
Long-term investments	17,013
Corporate securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term Investments	0
Long-term investments	0
Corporate securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term Investments	18,987
Long-term investments	$ 17,013
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2016.

Intangible Assets (Details)

Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Accumulated Amortization	$ (20,319)	$ (16,170)
Net Carrying Amount	12,999
Indefinite-lived trade name	3,600	3,600
Total intangible assets, gross carrying amount	36,918	36,918
Intangible assets, net	$ 16,599	$ 20,748	[1]
Developed technologies
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	60 months	60 months
Gross Carrying Amount	$ 15,077	$ 15,077
Accumulated Amortization	(9,616)	(8,245)
Net Carrying Amount	$ 5,461	$ 6,832
Customer lists
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	47 months	47 months
Gross Carrying Amount	$ 9,970	$ 9,970
Accumulated Amortization	(5,138)	(3,673)
Net Carrying Amount	$ 4,832	$ 6,297
Trade names
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	47 months	47 months
Gross Carrying Amount	$ 5,513	$ 5,513
Accumulated Amortization	(3,077)	(1,998)
Net Carrying Amount	$ 2,436	$ 3,515
Non-compete agreements
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	30 months	30 months
Gross Carrying Amount	$ 1,728	$ 1,728
Accumulated Amortization	(1,458)	(1,249)
Net Carrying Amount	$ 270	$ 479
Master service agreements
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	21 months	21 months
Gross Carrying Amount	$ 1,030	$ 1,030
Accumulated Amortization	(1,030)	(1,005)
Net Carrying Amount	$ 0	$ 25
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2016.

Intangible Assets - Additional

Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Acquisition-Related Intangible Assets
Finite Lived Intangible Assets [Line Items]
Amortization expense of acquisition related to acquired intangible assets	$ 1.4	$ 1.4	$ 4.1	$ 3.2

Intangible Assets - Estimated F

Intangible Assets - Estimated Future Amortization Expense Related to Intangible Assets (Details) $ in Thousands	Sep. 30, 2017USD ($)
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Remaining three months of 2017	$ 1,201
2,018	4,446
2,019	3,510
2,020	2,153
2,021	815
Thereafter	874
Net Carrying Amount	$ 12,999

Debt Obligations (Details)

Debt Obligations (Details) - Revolving Credit Facility - USD ($)	3 Months Ended	9 Months Ended			12 Months Ended
	Sep. 30, 2017	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2019	Sep. 30, 2016
Debt Instrument [Line Items]
Face amount						$ 30,000,000
Maximum borrowing capacity	$ 30,000,000		$ 30,000,000			$ 50,000,000
EBITDA calculation expense threshold, acquisition expenses permissible			6,000,000
EBITDA calculation expense threshold, nonrecurring expenses			2,000,000
Cash and cash equivalents minimum balance	25,000,000		30,000,000
EBITDA target				$ 25,000,000
Amount outstanding	$ 0		$ 0
LIBOR Rate
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage			0.25%
Total Leverage Ratio Less Than 1%
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage			1.50%
Total Leverage Ratio Greater Or Equal 1%
Debt Instrument [Line Items]
Unused capacity, commitment fee percentage			2.50%
Scenario, Forecast
Debt Instrument [Line Items]
EBITDA target		$ 30,000,000			$ 35,000,000

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Rental expense	$ 0.6	$ 0.5	$ 2	$ 1.4

Stockholders' Equity - Follow-o

Stockholders' Equity - Follow-on Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 08, 2017	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from follow-on offering, net of offering costs		$ 147,632	$ 0
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares sold	11,500,000
Price per share (in dollars per share)	$ 13.50
Proceeds from follow-on offering, net of offering costs	$ 147,600
Underwriting discounts and commissions	7,000
Offering costs	$ 600
Over-Allotment Option | Full Exercise Of Underwriters Option To Purchase Additional Shares | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares sold	1,500,000

Stockholders' Equity - Share-ba

Stockholders' Equity - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 10,091	$ 10,210	$ 27,468	$ 32,701
Cost of revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	73	46	228	115
Technology and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	3,706	3,449	10,334	11,207
Sales and marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	1,261	1,605	3,588	5,456
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 5,051	$ 5,110	$ 13,318	$ 15,923

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized share-based compensation			$ 0	$ 0
Stock options granted (in shares)		232,700	0
Weighted average grant date fair value (in dollars per share)	$ 2.58
Unrecognized compensation expense for stock options granted to employees, officers, directors, and consultants	$ 200,000		$ 200,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average vesting period for recognition of compensation expense			9 months 3 days
2016 Performance Period | RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average vesting period for recognition of compensation expense			1 year 10 months 13 days
Unrecognized compensation costs related to restricted stock units	$ 55,700,000		$ 55,700,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Details) - RSUs and PSUs	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Number of RSUs and PSUs Outstanding
Number of RSUs and PSUs Outstanding, Beginning (shares) | shares	14,142,109
Number of RSUs and PSUs, Granted (shares) | shares	6,425,919
Number of RSUs and PSUs, Released (shares) | shares	(4,968,509)
Number of RSUs and PSUs, Canceled (shares) | shares	(1,153,704)
Number of RSUs and PSUs Outstanding, Ending (shares) | shares	14,445,815
Weighted-Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Beginning balance (in dollars per share) | $ / shares	$ 5.20
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	8.75
Weighted Average Grant Date Fair Value, Released (in dollars per share) | $ / shares	5.67
Weighted Average Grant Date Fair Value, Canceled (in dollars per share) | $ / shares	6.01
Weighted Average Grant Date Fair Value, Ending balance (in dollars per share) | $ / shares	$ 6.57

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 598	$ 554	$ 1,961	$ 1,463

Restructuring Charges (Credit44

Restructuring Charges (Credits) - Restructuring Reserve (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Beginning balance			$ 306	$ 2,518	$ 2,518
Restructuring charges (credits)	$ 64	$ (100)	1,023	(298)	(423)
Cash payments			(1,029)		(1,789)
Write-offs			(20)
Ending balance	280		280		306
2017 Restructuring Plan | Workforce Reduction Costs
Restructuring Reserve [Roll Forward]
Beginning balance			0	0	0
Restructuring charges (credits)			927		0
Cash payments			(897)		0
Write-offs			0
Ending balance	30		30		0
2017 Restructuring Plan | Lease Termination and Other Costs
Restructuring Reserve [Roll Forward]
Beginning balance			0	0	0
Restructuring charges (credits)			138		0
Cash payments			(118)		0
Write-offs			(20)
Ending balance	0		0		0
2015 Restructuring Plan | Workforce Reduction Costs
Restructuring Reserve [Roll Forward]
Beginning balance			0	55	55
Restructuring charges (credits)			0		0
Cash payments			0		(55)
Write-offs			0
Ending balance	0		0		0
2015 Restructuring Plan | Lease Termination and Other Costs
Restructuring Reserve [Roll Forward]
Beginning balance			306	$ 2,463	2,463
Restructuring charges (credits)			(42)		(423)
Cash payments			(14)		(1,734)
Write-offs			0
Ending balance	$ 250		$ 250		$ 306

Restructuring Charges (Credit45

Restructuring Charges (Credits) - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)position	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges (credits)	$ 64	$ (100)	$ 1,023	$ (298)	$ (423)
Restructuring reserve	280		280		306	$ 2,518
Restructuring reserve, current	100		100
Restructuring reserve, noncurrent	200		$ 200
2017 Restructuring Plan | Workforce Reduction Costs
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated | position			50
Restructuring charges (credits)			$ 927		0
Restructuring reserve	30		30		0	0
2017 Restructuring Plan | Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges (credits)			138		0
Restructuring reserve	0		0		0	0
2015 Restructuring Plan | Workforce Reduction Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges (credits)			0		0
Restructuring reserve	0		0		0	55
2015 Restructuring Plan | Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges (credits)			(42)		(423)
Restructuring reserve	$ 250		$ 250		$ 306	$ 2,463

Related-Party Transactions (Det

Related-Party Transactions (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)board_member	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Adobe Systems | Chief Executive Officer
Related Party Transaction [Line Items]
Purchases from related party	$ 800,000	$ 700,000	$ 2,600,000	$ 2,500,000
Due to related parties	0		0		$ 300,000
Receivables from related party	0		0		0
Cengage | Chief Executive Officer
Related Party Transaction [Line Items]
Receivables from related party	300,000		300,000		100,000
Revenue from related party	1,200,000	600,000	1,800,000	600,000
Cengage | Board Of Directors Member
Related Party Transaction [Line Items]
Purchases from related party	4,700,000	2,800,000	9,500,000	7,200,000
Due to related parties	0		$ 0		0
Number of board members appointed to Board of Directors of related party | board_member			1
Groupon, Inc. | Chief Executive Officer
Related Party Transaction [Line Items]
Receivables from related party	0		$ 0		$ 0
Revenue from related party	0	0	0	0
Groupon, Inc. | Board Of Directors Member
Related Party Transaction [Line Items]
Purchases from related party	200,000	$ 200,000	$ 500,000	$ 500,000
Number of board members appointed to Board of Directors of related party | board_member			1
Payment Processing Fees | PayPal Holdings, Inc. | Immediate Family Member of Management or Principal Owner [Member]
Related Party Transaction [Line Items]
Number of board members appointed to Board of Directors of related party | board_member			1,000,000
Payment processing fees	$ 300,000		$ 800,000

Subsequent Event (Details)

Subsequent Event (Details) - Oct. 16, 2017 - Cogeon GmbH - Subsequent Event € in Millions, $ in Millions	USD ($)	EUR (€)	EUR (€)
Subsequent Event [Line Items]
Cash payment to acquire business	$ 15	€ 12.5
Contingent consideration arrangements, potential additional payments	$ 9		€ 7.5
Contingent consideration arrangements, potential additional payments, period	3 years	3 years
Restricted Stock Units (RSUs)
Subsequent Event [Line Items]
Potential additional stock issuance	$ 3.8		€ 3.2
Period of potential additional stock issuance	3 years	3 years