Chegg (CHGG) 10-Q 5 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 31, 2015
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, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		87,883,862

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	[1]
Current assets
Cash and cash equivalents	$ 80,941	$ 56,117
Short-term investments	21,365	33,346
Accounts receivable, net of allowance for doubtful accounts of $271 and $559 at September 30, 2015 and December 31, 2014, respectively	9,323	14,396
Prepaid expenses	5,786	3,091
Other current assets	33,834	3,864
Total current assets	151,249	110,814
Long-term investments	2,935	1,451
Textbook library, net	44,642	80,762
Property and equipment, net	18,537	18,369
Goodwill	91,301	91,301
Intangible assets, net	9,511	13,626
Other assets	3,882	1,804
Total assets	322,057	318,127
Current liabilities
Accounts payable	11,982	10,945
Deferred revenue	46,081	24,591
Accrued liabilities	39,674	31,183
Total current liabilities	97,737	66,719
Long-term liabilities
Total other long-term liabilities	4,261	4,365
Total liabilities	$ 101,998	$ 71,084
Commitments and contingencies (Note 7)
Stockholders' equity:
Preferred stock, $0.001 par value – 10,000,000 shares authorized, no shares issued and outstanding at September 30, 2015 and December 31, 2014	$ 0	$ 0
Common stock, $0.001 par value 400,000,000 shares authorized at September 30, 2015 and December 31, 2014; 87,762,853 and 84,008,043 shares issued and outstanding at September 30, 2015 and December 31, 2014, respectively	88	84
Additional paid-in capital	552,773	516,845
Accumulated other comprehensive loss	(89)	(13)
Accumulated deficit	(332,713)	(269,873)
Total stockholders' equity	220,059	247,043
Total liabilities and stockholders' equity	$ 322,057	$ 318,127
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2014.

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 271	$ 559
Preferred stock, par value	$ 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	$ 0.001	$ 0.001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	87,762,853	84,008,043
Common stock, shares outstanding	87,762,853	84,008,043

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net revenues:
Rental	$ 22,703	$ 38,923	$ 93,199	$ 128,036
Services	33,358	23,408	94,001	59,253
Sales	25,225	19,201	46,019	33,128
Net revenues:	81,286	81,532	233,219	220,417
Cost of revenues:
Rental	27,080	43,503	86,873	121,088
Services	10,377	8,218	32,189	20,786
Sales	24,263	16,560	44,407	30,488
Cost of revenues:	61,720	68,281	163,469	172,362
Gross profit	19,566	13,251	69,750	48,055
Operating expenses:
Technology and development	15,664	13,490	45,076	36,999
Sales and marketing	16,211	23,453	49,985	53,297
General and administrative	12,060	10,986	35,780	31,480
Restructuring charges	342	0	3,320	0
Gain on liquidation of textbooks	(909)	(2,044)	(2,649)	(5,844)
Total operating expenses	43,368	45,885	131,512	115,932
Loss from operations	(23,802)	(32,634)	(61,762)	(67,877)
Interest expense and other income, net:
Interest expense, net	(61)	(67)	(182)	(255)
Other income, net	85	541	217	817
Total interest expense and other income, net	24	474	35	562
Loss before provision for (benefit from) income taxes	(23,778)	(32,160)	(61,727)	(67,315)
Provision for (benefit from) income taxes	389	281	1,113	(869)
Net loss	$ (24,167)	$ (32,441)	$ (62,840)	$ (66,446)
Net loss per share, attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.28)	$ (0.39)	$ (0.73)	$ (0.80)
Weighted average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	87,706	83,688	86,419	82,963

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (24,167)	$ (32,441)	$ (62,840)	$ (66,446)
Other comprehensive (loss) income:
Change in unrealized gain (loss) on available for sale investments, net of tax	16	(18)	21	20
Change in foreign currency translation adjustments	(119)	(11)	(97)	(15)
Other comprehensive (loss) income:	(103)	(29)	(76)	5
Total comprehensive loss	$ (24,270)	$ (32,470)	$ (62,916)	$ (66,441)

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014
Cash flows from operating activities
Net loss	$ (62,840)		$ (66,446)
Adjustments to reconcile net loss to net cash provided by operating activities:
Textbook library depreciation expense	36,838		54,220
Other depreciation and amortization expense	9,180		7,823
Share-based compensation expense	31,784		27,205
Gain on liquidation of textbooks	(2,649)		(5,844)
Loss from write-offs of textbooks	4,534		10,133
Deferred income taxes	0		(1,626)
Other non-cash items	790		650
Change in assets and liabilities net of effect of acquisition of businesses:
Accounts receivable	(399)		(3,633)
Prepaid expenses and other current assets	(32,503)		(8,356)
Other assets	(204)		(147)
Accounts payable	1,977		(319)
Deferred revenue	21,490		49,528
Accrued liabilities	10,310		4,826
Other liabilities	(194)		(12)
Net cash provided by operating activities	18,114		68,002
Cash flows from investing activities
Purchases of textbooks	(32,226)		(99,469)
Proceeds from liquidations of textbooks	34,230		40,175
Purchases of marketable securities	(19,975)		(63,872)
Proceeds from sale of marketable securities	350		42,708
Maturities of marketable securities	29,989		38,230
Purchases of property and equipment	(5,884)		(3,807)
Acquisition of businesses, net of cash acquired	0		(43,872)
Purchase of strategic equity investment	(2,019)		0
Net cash provided by (used in) investing activities	4,465		(89,907)
Cash flows from financing activities
Common stock issued under stock plans, net	12,588		2,001
Payment of taxes related to the net share settlement of RSUs	(8,080)		(3,774)
Repurchase of common stock	(2,263)		0
Net cash provided by (used in) financing activities	2,245		(1,773)
Net increase (decrease) in cash and cash equivalents	24,824		(23,678)
Cash and cash equivalents, beginning of period	56,117	[1]	76,864
Cash and cash equivalents, end of period	80,941		53,186
Supplemental cash flow data:
Interest	76		88
Income taxes	686		518
Non-cash investing and financing activities:
Accrued purchases of long-lived assets	999		6,736
Issuance of common stock related to prior acquisition	$ 825		$ 1,585
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2014.

Background and Basis of Present

Background and Basis of Presentation	9 Months Ended
	Sep. 30, 2015
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 are driven by our passion to help students become active consumers in the educational process. Our integrated platform offers products and services that students need throughout the college lifecycle, from choosing a college through graduation and beyond. By helping students learn more in less time and at a lower cost, we help them improve the overall return on investment in education. In 2014, nearly 7.5 million students used our platform. Basis of Presentation The accompanying condensed consolidated balance sheet as of September 30, 2015 , the condensed consolidated statements of operations and the condensed consolidated statements of comprehensive loss for the three and nine months ended September 30, 2015 and 2014 , the condensed consolidated statements of cash flows for the nine months ended September 30, 2015 and 2014 , 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, 2015 , our results of operations for the three and nine months ended September 30, 2015 and 2014 , and cash flows for the nine months ended September 30, 2015 and 2014 . The results of operations for the three and nine months ended September 30, 2015 and cash flows for the nine months ended September 30, 2015 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, 2014 as 2014 . 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, 2014 (the Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). Except for restructuring charges and strategic investments, which are discussed below, 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. We have presented revenue and cost of revenues separately for rental, service and sale beginning with our Annual Report on Form 10-K. Rental revenue includes the rental of print textbooks for which we take title and bear the risk of loss; service revenue includes Chegg Study, brand advertising, eTextbooks, tutoring, enrollment marketing, and commissions we earn from Ingram and other e-commerce partners; sale revenue includes just-in-time sale of print textbooks and the sale of other required materials. We have reclassified amounts in the prior periods to conform to the current period presentation. None of the changes impact previously reported condensed consolidated revenue, cost of revenue, operating income, or earnings per share. 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 revenue 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 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. Restructuring Charges Restructuring charges are primarily comprised of severance costs, contract and program termination costs, asset impairments and costs of facility consolidation and closure. Restructuring charges are recorded upon approval of a formal management plan and are included in the operating results of the period in which such plan is approved and the expense becomes estimable. To estimate restructuring charges, management utilizes assumptions of the number of employees that would be involuntarily terminated and of future costs to operate and eventually vacate duplicate facilities. Severance and other employee separation costs are accrued when it is probable that benefits will be paid and the amount is reasonably estimable. The rates used in determining severance accruals are based on our policies and practices and negotiated settlements. Restructuring charges for employee workforce reductions are recorded upon employee notification for employees whose required continuing service period is 60 days or less and ratably over the employee’s continuing service period for employees whose required continuing service period is greater than 60 days. Strategic Investments We have entered into an equity investment in a privately-held business to achieve certain strategic business objectives. Our investment in equity securities of this privately-held business is accounted for under the cost method. We periodically review these investments for other-than-temporary declines in fair value based on the specific identification method and write down investments when an other-than-temporary decline has occurred. Any fair value estimates are made based on consideration of the current cash position, recent operational performance, and forecasts of the investees. Recent Accounting Pronouncements 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.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing net loss by weighted-average number of shares of common stock outstanding during the period, less 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 2015 2014 2015 2014 Numerator: Net loss $ (24,167 ) $ (32,441 ) $ (62,840 ) $ (66,446 ) Denominator: Weighted-average common shares outstanding 87,706 83,704 86,419 83,010 Less: Weighted-average unvested common shares subject to repurchase or forfeiture — (16 ) — (47 ) Weighted-average common shares used in computing basic and diluted net loss per share 87,706 83,688 86,419 82,963 Net loss per share, basic and diluted. $ (0.28 ) $ (0.39 ) $ (0.73 ) $ (0.80 ) The following potential shares of common stock outstanding were excluded from the computation of diluted net loss per share attributable to common stockholders because including them would have been anti-dilutive (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Options to purchase common stock 8,156 13,936 11,744 14,592 RSUs and PSUs 317 334 159 355 Employee stock purchase plan 6 — 14 — Common stock subject to repurchase or forfeiture — 9 — 9 Warrants to purchase common stock 200 996 335 996 Total common stock equivalents 8,679 15,275 12,252 15,952

Cash and Cash Equivalents, Inve

Cash and Cash Equivalents, Investments and Restricted Cash	9 Months Ended
	Sep. 30, 2015
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 (in thousands) as of September 30, 2015 and December 31, 2014 : September 30, 2015 December 31, 2014 Cost Net Unrealized Gain/(Loss) Fair Value Cost Net Unrealized Gain/(Loss) Fair Value Cash and cash equivalents: Cash $ 69,083 $ — $ 69,083 $ 49,836 $ — $ 49,836 Money market funds 10,108 — 10,108 5,828 — 5,828 Commercial paper 1,750 — 1,750 453 — 453 Total cash and cash equivalents $ 80,941 $ — $ 80,941 $ 56,117 $ — $ 56,117 Short-term investments: Commercial paper $ 6,948 $ — $ 6,948 $ 13,435 $ — $ 13,435 Corporate securities 14,415 2 14,417 18,426 (15 ) 18,411 Certificate of deposit — — — 1,499 1 1,500 Total short-term investments $ 21,363 $ 2 $ 21,365 $ 33,360 $ (14 ) $ 33,346 Long-term investments: Corporate securities $ 1,937 $ (5 ) $ 1,932 $ 1,453 $ (2 ) $ 1,451 Agency bond 1,001 2 1,003 — — — Long-term corporate securities $ 2,938 $ (3 ) $ 2,935 $ 1,453 $ (2 ) $ 1,451 Short-term restricted cash $ 300 $ — $ 300 $ 300 $ — $ 300 Long-term restricted cash 1,480 — 1,480 1,480 — 1,480 Total restricted cash $ 1,780 $ — $ 1,780 $ 1,780 $ — $ 1,780 The amortized cost and fair value of available-for-sale investments as of September 30, 2015 by contractual maturity were as follows (in thousands): Cost Fair Value Due in 1 year or less $ 23,113 $ 23,115 Due in 1-2 years 2,938 2,935 Investments not due at a single maturity date 10,108 10,108 Total $ 36,159 $ 36,158 Investments not due at a single maturity date in the preceding table consist of money market fund deposits and commercial paper. As of September 30, 2015 , 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 three 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, 2015 , we did not recognize any impairment charges. Strategic Investment During the three months ended September 30, 2015 we invested $2.0 million in a third party to expand our customer reach. This investment 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, 2015 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, 2015
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, 2015 and December 31, 2014 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2015 Total Quoted Prices Significant Assets: Cash equivalents: Money market funds $ 10,108 $ 10,108 $ — Commercial paper 1,750 — 1,750 Short-term investments: Commercial paper 6,948 — 6,948 Corporate securities 14,417 — 14,417 Long-term investments: Corporate securities 1,932 — 1,932 Agency bond 1,003 — 1,003 Total assets measured and recorded at fair value $ 36,158 $ 10,108 $ 26,050 December 31, 2014 Total Quoted Prices Significant Significant Assets: Cash equivalents: Money market funds $ 5,828 $ 5,828 $ — $ — Commercial paper 453 — 453 — Short-term investments: Commercial paper 13,435 — 13,435 — Corporate securities 18,411 — 18,411 — Certificate of deposit 1,500 — 1,500 — Long-term investments, corporate securities 1,451 — 1,451 Total assets measured and recorded at fair value $ 41,078 $ 5,828 $ 35,250 $ — Liabilities: Put option liability $ 1,079 $ — $ — $ 1,079 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 put option liability (Level 3) related to a previous acquisition that provided certain employees of the acquired company with the right to require us to acquire vested common shares at a stated contractual price had been fully exercised and the shares were repurchased from employees in the first quarter of 2015. We no longer hold any Level 3 assets or liabilities as of September 30, 2015 . 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, 2015
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	Intangible Assets Intangible assets as of September 30, 2015 and December 31, 2014 consist of the following (in thousands, except weighted-average amortization period): September 30, 2015 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 52 $ 9,417 $ (6,467 ) $ 2,950 Customer lists 20 2,820 (2,145 ) 675 Trade names 48 2,343 (773 ) 1,570 Non-compete agreements 28 1,220 (695 ) 525 Master service agreements 21 1,030 (839 ) 191 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 20,430 $ (10,919 ) $ 9,511 December 31, 2014 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Impairment Net Carrying Amount Developed technologies 50 $ 9,792 $ (5,000 ) $ (194 ) $ 4,598 Customer lists 15 4,363 (1,816 ) (829 ) 1,718 Trade names 44 3,132 (1,085 ) (39 ) 2,008 Non-compete agreements 21 1,637 (421 ) (278 ) 938 Master service agreements 21 1,030 (266 ) — 764 Corporate partnerships 0 243 (31 ) (212 ) — Indefinite-lived trade name — 3,600 — — 3,600 Total intangible assets $ 23,797 $ (8,619 ) $ (1,552 ) $ 13,626 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. During the three and nine months ended September 30, 2014 , amortization expense related to our acquired intangible assets totaled approximately $1.7 million and $3.3 million , respectively. As of September 30, 2015 , the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands): Remaining three months of 2015 $ 647 2016 2,238 2017 1,701 2018 1,018 2019 307 Total $ 5,911

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Debt Obligations	Debt Obligations In August 2013, we entered into a revolving credit facility with an aggregate principal amount of $50.0 million (the Revolving Credit Facility). In June 2014, we amended the Revolving Credit Facility to reduce the aggregate principal amount to $40.0 million with an accordion feature that, subject to certain financial criteria, allows us to borrow up to a total of $65.0 million . In August 2015, we amended the Revolving Credit Facility to reduce the financial covenant consolidated EBITDA requirements beginning the quarter ended June 30, 2015 and to reduce the aggregate principal amount to $30.0 million with an accordion feature that, subject to certain financial criteria, allows us to borrow up to a total of $55.0 million beginning the quarter ended December 31, 2015. The Revolving Credit Facility carries, 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 will expire in August 2016. The Revolving Credit Facility requires us to repay the outstanding balance at expiration, or to prepay the outstanding balance, if certain reporting and financial covenants are not maintained. These financial covenants are as follows: (1) maintain specified quarterly levels of consolidated EBITDA, which is defined as net income (loss) before tax plus interest expense, provision for (benefit from) income taxes, depreciation and amortization expense, non-cash share-based compensation expense and costs and expenses not to exceed $2.0 million in closing fees related to the revolving credit facility; and (2) maintain a leverage ratio greater than 1.5 to 1.0 as of the end of each quarter, based on the ratio of the consolidated outstanding debt balance to consolidated EBITDA for the period of the four fiscal quarters most recently ended. As of September 30, 2015 , we were in compliance with these financial covenants.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2015
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, 2015 related to our headquarters in Santa Clara, California, our office in San Francisco, California, and our warehouse 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. On April 10, 2015, we signed an agreement to sublease effectively one half of our warehouse in Kentucky. We expect this sublease agreement to generate $0.1 million of sublease income per month through the end of November 2016. Rental expense, net of sublease income, was approximately $0.6 million and $2.0 million in the three and nine months ended September 30, 2015 , respectively, and $0.9 million and $2.5 million in the three and nine months ended September 30, 2014 , 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, from time to time, we may 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, from time to time, also 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. Due to the preliminary status of the appeal by the Kentucky Department of Revenue and the uncertainties related to the appeal, we are unable to evaluate the likelihood of either a favorable or unfavorable outcome. We believe that it is reasonably possible that we will incur a loss; however, we cannot currently estimate a range of any possible losses we may experience in connection with this case. Accordingly, we are unable at this time to estimate the effects of this matter on our financial condition, results of operations, or cash flows. 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, 2015
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, 2015 .

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2015
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 2015 2014 2015 2014 Cost of revenues $ 103 $ 160 $ 318 $ 472 Technology and development 3,464 3,235 9,444 8,252 Sales and marketing 126 4,476 6,214 8,071 General and administrative 5,240 3,923 15,808 10,410 Total share-based compensation expense $ 8,933 $ 11,794 $ 31,784 $ 27,205 Fair Value of Stock Options We estimate the fair value of each stock option award using the Black-Scholes-Merton option-pricing model, which utilizes the estimated fair value of our common stock and requires input on the following subjective assumptions: Expected Term — The expected term for options granted to employees, officers, and directors is calculated as the midpoint between the vesting date and the end of the contractual term of the options. The expected term for options granted to consultants is determined using the remaining contractual life. Expected Volatility — The expected volatility is based on the average volatility of public companies within our peer group as our common stock has not been publicly trading for a long enough period to rely on our own expected volatility. Expected Dividends — The dividend assumption is based on our historical experience. To date we have not paid any dividends on our common stock. Risk-Free Interest Rate — The risk-free interest rate used in the valuation method is the implied yield currently available on the United States treasury zero-coupon issues, with a remaining term equal to the expected life term of our options. The following table summarizes the key assumptions used to determine the fair value of our stock options granted to employees, officers and directors: Nine Months Ended 2015 2014 Expected term (years) 5.50 6.07 Expected volatility 50.68 % 56.15 % Dividend yield — % — % Risk-free interest rate 1.75 % 1.91 % Weighted-average grant-date fair value per share $ 3.63 $ 3.82 No stock option awards were granted to employees in the three months ended September 30, 2015 and September 30, 2014 . 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 Employee Stock Purchase Plan Under the 2013 Employee Stock Purchase Plan (the 2013 ESPP), rights to purchase shares are generally granted during the second and fourth quarter of each year. The fair value of rights granted under the 2013 ESPP was estimated at the date of grant using the Black-Scholes-Merton option-pricing model. Stock Option Activity Stock option activity under our equity incentive plans was as follows: Options Outstanding Number of Options Outstanding Weighted- Average Exercise Price per Share Weighted-Average Remaining Contractual Term in Years Aggregate Intrinsic Value Balance at December 31, 2014 14,962,099 $ 8.53 7.11 $ 6,646,629 Granted 165,456 7.65 Exercised (1,735,179 ) 6.45 Canceled (860,706 ) 9.96 Balance at September 30, 2015 12,531,670 $ 8.71 6.70 $ 6,124,172 As of September 30, 2015 , our total unrecognized compensation expense for stock options granted to employees, officers, directors, and consultants was approximately $13.6 million , which will be recognized over a weighted-average vesting period of approximately 1.2 years . We recognize only the portion of the stock options granted to employees that is ultimately expected to vest as compensation expense. Estimated forfeitures are determined based on historical data and management’s expectation of exercise behaviors. Forfeiture rates and the resulting compensation expense are revised in subsequent periods if actual forfeitures differ from the estimate. No stock options were granted to consultants during the three and nine months ended September 30, 2015 and 2014 . Total share-based compensation expense for consultants was not significant for the three and nine months ended September 30, 2015 and 2014 . There was no capitalized share-based compensation expense as of September 30, 2015 or 2014 . RSU and PSU Activity RSUs and PSUs Outstanding Number of RSUs and PSUs Outstanding Weighted Average Grant Date Fair Value Balance at December 31, 2014 9,125,190 $ 6.25 Granted 7,478,370 6.86 Released (2,513,184 ) 7.78 Canceled (891,798 ) 6.54 Balance at September 30, 2015 13,198,578 $ 6.28 In February 2015, we granted PSUs under the 2013 Equity Incentive Plan (2013 Plan) to certain of our key employees. 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 Performance Period). Based on the achievement of the performance conditions during the Performance Period for the February 2015 grants, the final settlement will range between zero and 100% of the target shares underlying the PSU awards based on a specified objective formula approved by the Compensation Committee of the Board of Directors. If earned, these PSUs will vest annually over a two or three year period depending on the employee, with the initial vesting in February 2016. The target number of shares underlying the PSUs that were granted to certain key employees 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. No PSUs were granted in the three months ended September 30, 2015 . As of September 30, 2015 , we expect the performance objectives associated with these PSUs to meet the minimum threshold needed to vest. As of September 30, 2015 , we had a total of approximately $47.7 million of unrecognized compensation costs related to RSUs and PSUs that is expected to be recognized over the remaining weighted average period of 1.6 years .

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We recorded an income tax provision of approximately $0.4 million and $1.1 million for the three and nine months ended September 30, 2015 , respectively, and an income tax provision of approximately $0.3 million and an income tax benefit of $0.9 million for the three and nine months ended September 30, 2014 , respectively. 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. The income tax provision in the three months ended September 30, 2014 was the result of foreign and state income tax expense. The income tax benefit in the nine months ended September 30, 2014 , was primarily the result of the release of valuation allowance resulting from our acquisition of InstaEDU, offset by foreign and state income taxes.

Restructuring Charges

Restructuring Charges	9 Months Ended
	Sep. 30, 2015
Restructuring and Related Activities [Abstract]
Restructuring Charges	Restructuring Charges 2015 Restructuring Plan For the three and nine months ended September 30, 2015 , we recorded restructuring charges of $0.3 million and $3.3 million , respectively, related to the exit from our print coupon business and our Kentucky warehouse. The charges include one-time employee termination benefits for approximately 71 employees of $0.6 million and $1.8 million during the three and nine months ended September 30, 2015 , respectively, a lease termination and other costs credit of $0.3 million during the three months ended September 30, 2015 , and lease termination and other costs of $1.5 million for the nine months ended September 30, 2015 . As a result of the expanded partnership with Ingram, we expect to exit our warehouse facilities by the end of 2015. We expect to incur charges in 2015 under the restructuring plan related to these exit activities and related severance costs of approximately $4.0 million . Costs incurred to date related to employee termination benefits are expected to be paid within the next three months . 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 (in thousands): Workforce Reduction Costs Lease Termination and Other Costs Total Balances at January 1, 2015 $ — $ — $ — Restructuring charges 1,774 1,546 3,320 Cash payments (628 ) (483 ) (1,111 ) Write-offs — (331 ) (331 ) Balances at September 30, 2015 $ 1,146 $ 732 $ 1,878 As of September 30, 2015 , the $1.9 million liability was comprised of a short-term accrual of $1.6 million included within accrued liabilities and a long-term accrual of $0.3 million included within other liabilities on the condensed consolidated balance sheet.

Related-Party Transactions

Related-Party Transactions	9 Months Ended
	Sep. 30, 2015
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, 2015 , we had purchases of $1.1 million and $2.0 million , respectively, and during the three and nine months ended September 30, 2014 , we had purchases of $0.4 million and $0.8 million , respectively, of products from Adobe. We had $0.1 million in revenues in the nine months ended September 30, 2015 and $1.0 million in revenues in the nine months ended September 30, 2014 , respectively, from Adobe. We had $0.4 million and $0.1 million in payables as of September 30, 2015 and December 31, 2014 , respectively, to 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, 2015 , we had purchases of $2.9 million and $9.1 million , respectively, and during the three and nine months ended September 30, 2014 , we had purchases of $4.7 million and $10.8 million , respectively, of products from Cengage. We had $0.1 million in revenues from Cengage in both the three and nine months ended September 30, 2015 . We had $1.1 million and $0.1 million in payables as of September 30, 2015 and December 31, 2014 , respectively, to Cengage. We had $0.1 million in outstanding accounts receivables to Cengage as of December 31, 2014 . One of our board members is the Chief Executive Officer of Shutterfly Inc. (Shutterfly). During the nine months ended September 30, 2015 , we had purchases of $1.1 million of products from Shutterfly. We had $0.1 million in revenues in both the three and nine months ended September 30, 2015 and an immaterial amount and $0.1 million in revenues in the three and nine months ended September 30, 2014 , respectively, from Shutterfly. One of our board members is also a member of the Board of Directors of Synack Inc. (Synack). During the three and nine months ended September 30, 2015 , we had purchases of $0.1 million of services from Synack. The terms of our contracts with the above related parties are consistent with our contracts with other independent parties.

Background and Basis of Prese19

Background and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated balance sheet as of September 30, 2015 , the condensed consolidated statements of operations and the condensed consolidated statements of comprehensive loss for the three and nine months ended September 30, 2015 and 2014 , the condensed consolidated statements of cash flows for the nine months ended September 30, 2015 and 2014 , 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, 2015 , our results of operations for the three and nine months ended September 30, 2015 and 2014 , and cash flows for the nine months ended September 30, 2015 and 2014 . The results of operations for the three and nine months ended September 30, 2015 and cash flows for the nine months ended September 30, 2015 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, 2014 as 2014 .
Revenue Recognition	We have presented revenue and cost of revenues separately for rental, service and sale beginning with our Annual Report on Form 10-K. Rental revenue includes the rental of print textbooks for which we take title and bear the risk of loss; service revenue includes Chegg Study, brand advertising, eTextbooks, tutoring, enrollment marketing, and commissions we earn from Ingram and other e-commerce partners; sale revenue includes just-in-time sale of print textbooks and the sale of other required materials. We have reclassified amounts in the prior periods to conform to the current period presentation. None of the changes impact previously reported condensed consolidated revenue, cost of revenue, operating income, or earnings per share.
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 revenue 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 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.
Restructuring Charges	Restructuring Charges Restructuring charges are primarily comprised of severance costs, contract and program termination costs, asset impairments and costs of facility consolidation and closure. Restructuring charges are recorded upon approval of a formal management plan and are included in the operating results of the period in which such plan is approved and the expense becomes estimable. To estimate restructuring charges, management utilizes assumptions of the number of employees that would be involuntarily terminated and of future costs to operate and eventually vacate duplicate facilities. Severance and other employee separation costs are accrued when it is probable that benefits will be paid and the amount is reasonably estimable. The rates used in determining severance accruals are based on our policies and practices and negotiated settlements. Restructuring charges for employee workforce reductions are recorded upon employee notification for employees whose required continuing service period is 60 days or less and ratably over the employee’s continuing service period for employees whose required continuing service period is greater than 60 days.
Strategic Investments	Strategic Investments We have entered into an equity investment in a privately-held business to achieve certain strategic business objectives. Our investment in equity securities of this privately-held business is accounted for under the cost method. We periodically review these investments for other-than-temporary declines in fair value based on the specific identification method and write down investments when an other-than-temporary decline has occurred. Any fair value estimates are made based on consideration of the current cash position, recent operational performance, and forecasts of the investees.

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss Per Share	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 2015 2014 2015 2014 Numerator: Net loss $ (24,167 ) $ (32,441 ) $ (62,840 ) $ (66,446 ) Denominator: Weighted-average common shares outstanding 87,706 83,704 86,419 83,010 Less: Weighted-average unvested common shares subject to repurchase or forfeiture — (16 ) — (47 ) Weighted-average common shares used in computing basic and diluted net loss per share 87,706 83,688 86,419 82,963 Net loss per share, basic and diluted. $ (0.28 ) $ (0.39 ) $ (0.73 ) $ (0.80 )
Common Shares Outstanding Excluded from Computation of Diluted Net Loss Per Share	The following potential shares of common stock outstanding were excluded from the computation of diluted net loss per share attributable to common stockholders because including them would have been anti-dilutive (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Options to purchase common stock 8,156 13,936 11,744 14,592 RSUs and PSUs 317 334 159 355 Employee stock purchase plan 6 — 14 — Common stock subject to repurchase or forfeiture — 9 — 9 Warrants to purchase common stock 200 996 335 996 Total common stock equivalents 8,679 15,275 12,252 15,952

Cash and Cash Equivalents, In21

Cash and Cash Equivalents, Investments and Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2015
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 (in thousands) as of September 30, 2015 and December 31, 2014 : September 30, 2015 December 31, 2014 Cost Net Unrealized Gain/(Loss) Fair Value Cost Net Unrealized Gain/(Loss) Fair Value Cash and cash equivalents: Cash $ 69,083 $ — $ 69,083 $ 49,836 $ — $ 49,836 Money market funds 10,108 — 10,108 5,828 — 5,828 Commercial paper 1,750 — 1,750 453 — 453 Total cash and cash equivalents $ 80,941 $ — $ 80,941 $ 56,117 $ — $ 56,117 Short-term investments: Commercial paper $ 6,948 $ — $ 6,948 $ 13,435 $ — $ 13,435 Corporate securities 14,415 2 14,417 18,426 (15 ) 18,411 Certificate of deposit — — — 1,499 1 1,500 Total short-term investments $ 21,363 $ 2 $ 21,365 $ 33,360 $ (14 ) $ 33,346 Long-term investments: Corporate securities $ 1,937 $ (5 ) $ 1,932 $ 1,453 $ (2 ) $ 1,451 Agency bond 1,001 2 1,003 — — — Long-term corporate securities $ 2,938 $ (3 ) $ 2,935 $ 1,453 $ (2 ) $ 1,451 Short-term restricted cash $ 300 $ — $ 300 $ 300 $ — $ 300 Long-term restricted cash 1,480 — 1,480 1,480 — 1,480 Total restricted cash $ 1,780 $ — $ 1,780 $ 1,780 $ — $ 1,780
Contractual Maturity of Available-for-Sale Investments	The amortized cost and fair value of available-for-sale investments as of September 30, 2015 by contractual maturity were as follows (in thousands): Cost Fair Value Due in 1 year or less $ 23,113 $ 23,115 Due in 1-2 years 2,938 2,935 Investments not due at a single maturity date 10,108 10,108 Total $ 36,159 $ 36,158

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2015
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, 2015 and December 31, 2014 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2015 Total Quoted Prices Significant Assets: Cash equivalents: Money market funds $ 10,108 $ 10,108 $ — Commercial paper 1,750 — 1,750 Short-term investments: Commercial paper 6,948 — 6,948 Corporate securities 14,417 — 14,417 Long-term investments: Corporate securities 1,932 — 1,932 Agency bond 1,003 — 1,003 Total assets measured and recorded at fair value $ 36,158 $ 10,108 $ 26,050 December 31, 2014 Total Quoted Prices Significant Significant Assets: Cash equivalents: Money market funds $ 5,828 $ 5,828 $ — $ — Commercial paper 453 — 453 — Short-term investments: Commercial paper 13,435 — 13,435 — Corporate securities 18,411 — 18,411 — Certificate of deposit 1,500 — 1,500 — Long-term investments, corporate securities 1,451 — 1,451 Total assets measured and recorded at fair value $ 41,078 $ 5,828 $ 35,250 $ — Liabilities: Put option liability $ 1,079 $ — $ — $ 1,079

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2015
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	Intangible assets as of September 30, 2015 and December 31, 2014 consist of the following (in thousands, except weighted-average amortization period): September 30, 2015 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies 52 $ 9,417 $ (6,467 ) $ 2,950 Customer lists 20 2,820 (2,145 ) 675 Trade names 48 2,343 (773 ) 1,570 Non-compete agreements 28 1,220 (695 ) 525 Master service agreements 21 1,030 (839 ) 191 Indefinite-lived trade name — 3,600 — 3,600 Total intangible assets $ 20,430 $ (10,919 ) $ 9,511 December 31, 2014 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Impairment Net Carrying Amount Developed technologies 50 $ 9,792 $ (5,000 ) $ (194 ) $ 4,598 Customer lists 15 4,363 (1,816 ) (829 ) 1,718 Trade names 44 3,132 (1,085 ) (39 ) 2,008 Non-compete agreements 21 1,637 (421 ) (278 ) 938 Master service agreements 21 1,030 (266 ) — 764 Corporate partnerships 0 243 (31 ) (212 ) — Indefinite-lived trade name — 3,600 — — 3,600 Total intangible assets $ 23,797 $ (8,619 ) $ (1,552 ) $ 13,626
Estimated Future Amortization Expense Related to Intangible Assets	As of September 30, 2015 , the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands): Remaining three months of 2015 $ 647 2016 2,238 2017 1,701 2018 1,018 2019 307 Total $ 5,911

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2015
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 2015 2014 2015 2014 Cost of revenues $ 103 $ 160 $ 318 $ 472 Technology and development 3,464 3,235 9,444 8,252 Sales and marketing 126 4,476 6,214 8,071 General and administrative 5,240 3,923 15,808 10,410 Total share-based compensation expense $ 8,933 $ 11,794 $ 31,784 $ 27,205
Summary of Assumptions Used to Determine Fair Value of Stock Options Granted	The following table summarizes the key assumptions used to determine the fair value of our stock options granted to employees, officers and directors: Nine Months Ended 2015 2014 Expected term (years) 5.50 6.07 Expected volatility 50.68 % 56.15 % Dividend yield — % — % Risk-free interest rate 1.75 % 1.91 % Weighted-average grant-date fair value per share $ 3.63 $ 3.82
Summary of Stock Option Activity	ption activity under our equity incentive plans was as follows: Options Outstanding Number of Options Outstanding Weighted- Average Exercise Price per Share Weighted-Average Remaining Contractual Term in Years Aggregate Intrinsic Value Balance at December 31, 2014 14,962,099 $ 8.53 7.11 $ 6,646,629 Granted 165,456 7.65 Exercised (1,735,179 ) 6.45 Canceled (860,706 ) 9.96 Balance at September 30, 2015 12,531,670 $ 8.71 6.70 $ 6,124,172
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, 2014 9,125,190 $ 6.25 Granted 7,478,370 6.86 Released (2,513,184 ) 7.78 Canceled (891,798 ) 6.54 Balance at September 30, 2015 13,198,578 $ 6.28

Restructuring Charges (Tables)

Restructuring Charges (Tables)	9 Months Ended
	Sep. 30, 2015
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 Balances at January 1, 2015 $ — $ — $ — Restructuring charges 1,774 1,546 3,320 Cash payments (628 ) (483 ) (1,111 ) Write-offs — (331 ) (331 ) Balances at September 30, 2015 $ 1,146 $ 732 $ 1,878

Background and Basis of Prese26

Background and Basis of Presentation - Additional Information (Details)	12 Months Ended
	Dec. 31, 2014student
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of students who have used our learning platform (nearly 7.5 million)	7,500,000

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, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator:
Net loss	$ (24,167)	$ (32,441)	$ (62,840)	$ (66,446)
Denominator:
Weighted-average common shares outstanding	87,706	83,704	86,419	83,010
Less: Weighted-average unvested common shares subject to repurchase or forfeiture	0	(16)	0	(47)
Weighted-average common shares used in computing basic and diluted net loss per share	87,706	83,688	86,419	82,963
Net loss per share, basic and diluted.	$ (0.28)	$ (0.39)	$ (0.73)	$ (0.80)

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, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	8,679	15,275	12,252	15,952
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	8,156	13,936	11,744	14,592
RSUs and PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	317	334	159	355
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	6	0	14	0
Common stock subject to repurchase or forfeiture
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	0	9	0	9
Warrants | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents	200	996	335	996

Cash and Cash Equivalents, In29

Cash and Cash Equivalents, Investments and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	$ 80,941	$ 56,117
Net Unrealized Gain/(Loss)	0	0
Fair Value	80,941	56,117
Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	21,363	33,360
Net Unrealized Gain/(Loss)	2	(14)
Fair Value	21,365	33,346
Short-term Investments | Corporate securities
Schedule Of Available For Sale Securities [Line Items]
Cost	14,415	18,426
Net Unrealized Gain/(Loss)	2	(15)
Fair Value	14,417	18,411
Long-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	2,938	1,453
Net Unrealized Gain/(Loss)	(3)	(2)
Fair Value	2,935	1,451
Long-term Investments | Corporate securities
Schedule Of Available For Sale Securities [Line Items]
Cost	1,937	1,453
Net Unrealized Gain/(Loss)	(5)	(2)
Fair Value	1,932	1,451
Long-term Investments | Agency bond
Schedule Of Available For Sale Securities [Line Items]
Cost	1,001	0
Net Unrealized Gain/(Loss)	2	0
Fair Value	1,003	0
Cash | Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	69,083	49,836
Net Unrealized Gain/(Loss)	0	0
Fair Value	69,083	49,836
Money market funds | Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	10,108	5,828
Net Unrealized Gain/(Loss)	0	0
Fair Value	10,108	5,828
Commercial paper | Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Cost	1,750	453
Net Unrealized Gain/(Loss)	0	0
Fair Value	1,750	453
Commercial paper | Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	6,948	13,435
Net Unrealized Gain/(Loss)	0	0
Fair Value	6,948	13,435
Certificate of deposit | Short-term Investments
Schedule Of Available For Sale Securities [Line Items]
Cost	0	1,499
Net Unrealized Gain/(Loss)	0	1
Fair Value	0	1,500
Short-term restricted cash
Schedule Of Available For Sale Securities [Line Items]
Cost	300	300
Net Unrealized Gain/(Loss)	0	0
Fair Value	300	300
Long-term restricted cash
Schedule Of Available For Sale Securities [Line Items]
Cost	1,480	1,480
Net Unrealized Gain/(Loss)	0	0
Fair Value	1,480	1,480
Total restricted cash
Schedule Of Available For Sale Securities [Line Items]
Cost	1,780	1,780
Net Unrealized Gain/(Loss)	0	0
Fair Value	$ 1,780	$ 1,780

Cash and Cash Equivalents, In30

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, 2015	Sep. 30, 2015	Sep. 30, 2014
Amortized Cost
Due in 1 year or less	$ 23,113	$ 23,113
Due in 1 year or less	2,938	2,938
Investments not due at a single maturity date	10,108	10,108
Total	36,159	36,159
Fair Value
Due in 1 year or less	23,115	23,115
Due in 1 year or less	2,935	2,935
Investments not due at a single maturity date	10,108	10,108
Total	36,158	$ 36,158
Weighted average maturity of investment securities		3 months
Investments in non-marketable equity investments		$ 2,019	$ 0
Equity Investments
Fair Value
Investments in non-marketable equity investments	$ 2,000

Fair Value Measurement - Financ

Fair Value Measurement - Financial Instruments Measured and Recorded at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Assets:
Short-term investments	$ 21,365	$ 33,346	[1]
Fair Value on Recurring Basis
Assets:
Total assets measured and recorded at fair value	36,158	41,078
Liabilities:
Put option liability		1,079
Fair Value on Recurring Basis | Corporate securities
Assets:
Short-term investments	14,417	18,411
Long-term investments	1,932	1,451
Fair Value on Recurring Basis | Agency bond
Assets:
Long-term investments	1,003
Fair Value on Recurring Basis | Money market funds
Assets:
Cash equivalents	10,108	5,828
Fair Value on Recurring Basis | Commercial paper
Assets:
Cash equivalents	1,750	453
Short-term investments	6,948	13,435
Fair Value on Recurring Basis | Certificate of deposit
Assets:
Short-term investments		1,500
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured and recorded at fair value	10,108	5,828
Fair Value on Recurring Basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Assets:
Cash equivalents	10,108	5,828
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured and recorded at fair value	26,050	35,250
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Corporate securities
Assets:
Short-term investments	14,417	18,411
Long-term investments	1,932	1,451
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Agency bond
Assets:
Long-term investments	1,003
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Cash equivalents	1,750	453
Short-term investments	$ 6,948	13,435
Fair Value on Recurring Basis | Significant Other Observable Inputs (Level 2) | Certificate of deposit
Assets:
Short-term investments		1,500
Fair Value on Recurring Basis | Significant Unobservable Inputs (Level 3)
Liabilities:
Put option liability		$ 1,079
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2014.

Intangible Assets (Details)

Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Finite Lived Intangible Assets [Line Items]
Accumulated Amortization	$ (10,919)	$ (8,619)
Impairment		(1,552)
Net Carrying Amount	5,911
Indefinite-lived trade name	3,600	3,600
Total intangible assets, gross carrying amount	20,430	23,797
Intangible assets, net	$ 9,511	$ 13,626	[1]
Developed technologies
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	52 months	50 months
Gross Carrying Amount	$ 9,417	$ 9,792
Accumulated Amortization	(6,467)	(5,000)
Impairment		(194)
Net Carrying Amount	$ 2,950	$ 4,598
Customer lists
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	20 months	15 months
Gross Carrying Amount	$ 2,820	$ 4,363
Accumulated Amortization	(2,145)	(1,816)
Impairment		(829)
Net Carrying Amount	$ 675	$ 1,718
Trade names
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	48 months	44 months
Gross Carrying Amount	$ 2,343	$ 3,132
Accumulated Amortization	(773)	(1,085)
Impairment		(39)
Net Carrying Amount	$ 1,570	$ 2,008
Non-compete agreements
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	28 months	21 months
Gross Carrying Amount	$ 1,220	$ 1,637
Accumulated Amortization	(695)	(421)
Impairment		(278)
Net Carrying Amount	$ 525	$ 938
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	(839)	(266)
Impairment		0
Net Carrying Amount	$ 191	$ 764
Corporate partnerships
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)		0 months
Gross Carrying Amount		$ 243
Accumulated Amortization		(31)
Impairment		(212)
Net Carrying Amount		$ 0
[1]	Derived from audited consolidated financial statements as of and for the year ended December 31, 2014.

Intangible Assets - Additional

Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Acquisition-Related Intangible Assets
Finite Lived Intangible Assets [Line Items]
Amortization expense of acquisition related to acquired intangible assets	$ 1.1	$ 1.7	$ 4.1	$ 3.3

Intangible Assets - Estimated F

Intangible Assets - Estimated Future Amortization Expense Related to Intangible Assets (Details) $ in Thousands	Sep. 30, 2015USD ($)
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Remaining three months of 2015	$ 647
2,016	2,238
2,017	1,701
2,018	1,018
2,019	307
Net Carrying Amount	$ 5,911

Debt Obligations - Additional I

Debt Obligations - Additional Information (Details) - Revolving Credit Facility	9 Months Ended
	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Aug. 31, 2013USD ($)
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity		$ 30,000,000	$ 40,000,000	$ 50,000,000
Credit facility, maximum borrowing capacity		$ 55,000,000	$ 65,000,000
Consolidated EBITDA	$ 2,000,000
Ratio of total debt outstanding to EBITDA	1.5
Base Interest Rate
Debt Instrument [Line Items]
Marginal interest rate	0.50%
One-Month LIBOR
Debt Instrument [Line Items]
Marginal interest rate	1.00%
Maximum | LIBOR Rate
Debt Instrument [Line Items]
Marginal interest rate	4.50%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Apr. 10, 2015	Dec. 31, 2012	Jul. 31, 2010
Commitments and Contingencies Disclosure [Abstract]
Rental expense	$ 600	$ 900	$ 2,000	$ 2,500
Future sublease income per month (through November 2016)					$ 100
Property tax assessment							$ 1,000
Offer to the tax authority excluding tax and penalties						$ 150

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense for stock options granted to employees, officers, directors, and consultants		$ 13,600,000		$ 13,600,000
Number of Options, Granted				165,456
Capitalized share-based compensation expense				$ 0	$ 0
Cash remitted to tax authorities related to RSU settlement				8,080,000	3,774,000
Share-based compensation expense		8,933,000	$ 11,794,000	$ 31,784,000	$ 27,205,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-IPO shares settled			358		1,285,619
Shares withheld			27		527,805
Cash remitted to tax authorities related to RSU settlement		$ 100,000			$ 3,600,000
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
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average vesting period for recognition of compensation expense				1 year 2 months 27 days
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		0		2,300,824
Performance based restricted stock unit award granted weighted average grant date fair value				$ 6.59
Performance-based restricted stock units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards				2 years
Settlement of performance based restricted stock unit awards percentage	0.00%
Performance-based restricted stock units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock awards				3 years
Settlement of performance based restricted stock unit awards percentage	100.00%
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				1 year 7 months 2 days
Performance based restricted stock unit award granted to executive officers				7,478,370
Performance based restricted stock unit award granted weighted average grant date fair value				$ 6.86
Awards forfeited				891,798
Unrecognized compensation costs related to restricted stock units		$ 47,700,000		$ 47,700,000
Consultant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Granted		0	0	0	0
Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Granted		0	0

Stockholders' Equity - Share-ba

Stockholders' Equity - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 8,933	$ 11,794	$ 31,784	$ 27,205
Cost of revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	103	160	318	472
Technology and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	3,464	3,235	9,444	8,252
Sales and marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	126	4,476	6,214	8,071
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 5,240	$ 3,923	$ 15,808	$ 10,410

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Assumptions (Details) - Stock Options - $ / shares	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)	5 years 6 months	6 years 26 days
Expected volatility	50.68%	56.15%
Dividend yield	0.00%	0.00%
Risk-free interest rate	1.75%	1.91%
Weighted-average grant-date fair value per share (in dollars per share)	$ 3.63	$ 3.82

Stockholders' Equity - Summar40

Stockholders' Equity - Summary of Stock Option Activity (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares
Number of Options Outstanding
Number of Options Outstanding, Beginning | shares	14,962,099
Number of Options, Granted | shares	165,456
Number of Options, Exercised | shares	(1,735,179)
Number of Options, Canceled | shares	(860,706)
Number of Options Outstanding, Ending | shares	12,531,670	14,962,099
Weighted-Average Exercise Price per Share
Weighted Average Exercise Price per Share, Outstanding, Beginning	$ 8.53
Weighted Average Exercise Price per Share, Granted	7.65
Weighted-Average Exercise Price per Share, Exercised	6.45
Weighted-Average Exercise Price per Share, Canceled	9.96
Weighted Average Exercise Price per Share, Outstanding, Ending	$ 8.71	$ 8.53
Options outstanding, weighted-average remaining contractual term in years	6 years 8 months 12 days	7 years 1 month 9 days
Options outstanding, aggregate intrinsic value | $	$ 6,124,172	$ 6,646,629

Stockholders' Equity - Summar41

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) and Performance Share Units (PSUs)	9 Months Ended
	Sep. 30, 2015$ / sharesshares
Restricted Stock Units Outstanding
Number of Restricted Stock Units Outstanding, Beginning | shares	9,125,190
Number of Restricted Stock Units, Granted | shares	7,478,370
Number of Restricted Stock Units, Released | shares	(2,513,184)
Number of Restricted Stock Units, Canceled | shares	(891,798)
Number of Restricted Stock Units Outstanding, Ending | shares	13,198,578
Weighted-Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Beginning balance	$ 6.25
Weighted Average Grant Date Fair Value, Granted	6.86
Weighted Average Grant Date Fair Value, Released	7.78
Weighted Average Grant Date Fair Value, Canceled	6.54
Weighted Average Grant Date Fair Value, Ending balance	$ 6.28

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Provision for (benefit from) income taxes	$ 389	$ 281	$ 1,113	$ (869)

Restructuring Charges (Details)

Restructuring Charges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Restructuring Reserve [Roll Forward]
Restructuring charges	$ 342	$ 0	$ 3,320	$ 0
2015 Restructuring Plan
Restructuring Reserve [Roll Forward]
Balances at January 1, 2015			0
Restructuring charges	300		3,320
Cash payments			(1,111)
Write-offs			(331)
Balances at September 30, 2015	1,878		1,878
2015 Restructuring Plan | Workforce Reduction Costs
Restructuring Reserve [Roll Forward]
Balances at January 1, 2015			0
Restructuring charges	600		1,774
Cash payments			(628)
Write-offs			0
Balances at September 30, 2015	1,146		1,146
2015 Restructuring Plan | Lease Termination and Other Costs
Restructuring Reserve [Roll Forward]
Balances at January 1, 2015			0
Restructuring charges	(300)		1,546
Cash payments			(483)
Write-offs			(331)
Balances at September 30, 2015	$ 732		$ 732

Restructuring Charges - Narrati

Restructuring Charges - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)position	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 342	$ 0	$ 3,320	$ 0
2015 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	300		3,320
Restructuring reserve	1,878		1,878		$ 0
Restructuring reserve, current	1,600		1,600
Restructuring reserve, noncurrent	300		300
Workforce Reduction Costs | 2015 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	600		$ 1,774
Number of positions eliminated | position			71
Restructuring reserve	1,146		$ 1,146		0
Lease Termination and Other Costs | 2015 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(300)		1,546
Restructuring reserve	732		732		$ 0
Minimum | Employee Severance | 2015 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Expected cost remaining	$ 4,000		$ 4,000

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)board_member	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Adobe Systems | Chief Executive Officer
Related Party Transaction [Line Items]
Purchases from related party	$ 1.1	$ 0.4	$ 2	$ 0.8
Revenue from related parties			0.1	1
Due to related parties	0.4		0.4		$ 0.1
Cengage | Board Of Directors Member
Related Party Transaction [Line Items]
Purchases from related party	2.9	4.7	9.1	10.8
Revenue from related parties	0.1		0.1
Due to related parties	1.1		$ 1.1		0.1
Due from related parties					$ 0.1
Number of board members appointed to Board of Directors of related party | board_member			1
Shutterfly Inc (Shutterfly) | Chief Executive Officer
Related Party Transaction [Line Items]
Purchases from related party	1.1
Revenue from related parties	0.1	$ 0	$ 0.1	$ 0.1
Number of board members appointed to chief executive officer of related party | board_member			1
Synack Inc. | Board Of Directors Member
Related Party Transaction [Line Items]
Purchases from related party	$ 0.1		$ 0.1
Number of board members appointed to Board of Directors of related party | board_member			1