Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2018	Jul. 27, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	CHEGG, INC
Entity Central Index Key	0001364954
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		113,960,276

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 384,926	$ 126,457
Short-term investments	80,938	81,742
Accounts receivable, net of allowance for doubtful accounts of $333 and $259 at June 30, 2018 and December 31, 2017, respectively	8,096	10,855
Prepaid expenses	8,707	2,043
Other current assets	7,742	7,845
Total current assets	490,409	228,942
Long-term investments	15,957	20,305
Property and equipment, net	51,516	47,493
Goodwill	135,842	125,272
Intangible assets, net	22,591	21,153
Other assets	4,256	3,765
Total assets	720,571	446,930
Current liabilities
Accounts payable	5,337	7,049
Deferred revenue	13,710	13,440
Accrued liabilities	29,460	31,074
Total current liabilities	48,507	51,563
Long-term liabilities
Convertible senior notes, net	276,578	0
Other long-term liabilities	6,767	4,305
Total long-term liabilities	283,345	4,305
Total liabilities	331,852	55,868
Commitments and contingencies (Note 10)
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; 113,551,003 and 109,667,640 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	114	110
Additional paid-in capital	787,480	782,845
Accumulated other comprehensive loss	(661)	(282)
Accumulated deficit	(398,214)	(391,611)
Total stockholders' equity	388,719	391,062
Total liabilities and stockholders' equity	$ 720,571	$ 446,930

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 333	$ 259
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	113,551,003	109,667,640
Common stock, shares outstanding	113,551,003	109,667,640

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)
shares in Thousands, $ in Thousands

3 Months Ended

6 Months Ended

Jun. 30, 2018

Jun. 30, 2017

Jun. 30, 2018

Jun. 30, 2017

Income Statement [Abstract]

Net revenues:

$ 74,222

$ 56,317

$ 151,171

$ 118,919

Cost of revenues:

17,784

17,042

38,008

38,438

Gross profit

56,438

39,275

113,163

80,481

Operating expenses:

Research and development

26,218

19,899

51,751

39,201

Sales and marketing

11,437

10,098

26,773

26,062

General and administrative

19,479

14,501

37,735

29,843

Restructuring charges

15

59

235

959

Gain on liquidation of textbooks

0

(4,766)

^[1]

Total operating expenses

57,149

44,557

116,494

91,299

Loss from operations

(711)

(5,282)

(3,331)

(10,818)

Interest expense and other income (expense), net:

Interest expense, net

(3,664)

(18)

(3,684)

(37)

Other income (expense), net

894

(9)

1,458

(208)

Total interest expense and other income (expense), net

(2,770)

(27)

(2,226)

(245)

Loss before provision for income taxes

(3,481)

(5,309)

(5,557)

(11,063)

Provision for income taxes

428

716

969

1,363

Net loss

$ (3,909)

$ (6,025)

^[1]

$ (6,526)

$ (12,426)

^[1]

Net loss per share, basic and diluted (in dollars per share)

$ (0.03)

$ (0.06)

$ (0.13)

Weighted average shares used to compute net loss per share, basic and diluted (in shares)

112,738

95,047

111,826

93,943

[1]	Adjusted to reflect the adoption of ASU 2016-18. See Note 1 for more information.

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($)
$ in Thousands

3 Months Ended

6 Months Ended

Jun. 30, 2018

Jun. 30, 2017

Jun. 30, 2018

Jun. 30, 2017

Statement of Comprehensive Income [Abstract]

Net loss

$ (3,909)

$ (6,025)

^[1]

$ (6,526)

$ (12,426)

^[1]

Other comprehensive (loss) income:

Change in net unrealized loss on available for sale investments

114

0

23

0

Change in foreign currency translation adjustments, net of tax

(913)

153

(402)

252

Other comprehensive (loss) income

(799)

153

(379)

252

Total comprehensive loss

$ (4,708)

$ (5,872)

$ (6,905)

$ (12,174)

[1]	Adjusted to reflect the adoption of ASU 2016-18. See Note 1 for more information.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Thousands

6 Months Ended

Jun. 30, 2018

Jun. 30, 2017

^[1]

Cash flows from operating activities

Net loss

$ (6,526)

$ (12,426)

Adjustments to reconcile net loss to net cash provided by operating activities:

Depreciation and amortization expense

10,665

9,093

Share-based compensation expense

23,685

17,377

Gain on liquidation of textbooks

0

(4,766)

Loss from write-offs of textbooks

0

314

Interest accretion on deferred consideration

0

(626)

Amortization of debt discount and issuance costs

3,421

0

Deferred income taxes

(315)

0

Other non-cash items

115

(55)

Change in assets and liabilities:

Accounts receivable

2,609

1,989

Prepaid expenses and other current assets

(6,773)

9,072

Other assets

(500)

473

Accounts payable

(1,712)

(3,591)

Deferred revenue

270

(2,379)

Accrued liabilities

(2,678)

1,181

Other liabilities

1,254

858

Net cash provided by operating activities

23,515

16,514

Cash flows from investing activities

Proceeds from liquidations of textbooks

0

6,943

Purchases of marketable securities

(66,634)

0

Maturities of marketable securities

71,980

0

Purchases of property and equipment

(10,087)

(12,507)

Acquisition of business, net of cash acquired

(14,438)

0

Net cash used in investing activities

(19,179)

(5,564)

Cash flows from financing activities

Common stock issued under stock plans, net

18,050

9,765

Payment of taxes related to the net share settlement of equity awards

(40,314)

(14,850)

Payment of deferred cash consideration related to acquisitions

0

(16,750)

Proceeds from issuance of convertible senior notes, net of issuance costs

335,601

0

Purchase of convertible senior notes capped call

(39,227)

0

Repurchase of common stock

(20,000)

0

Net cash provided by (used in) financing activities

254,110

(21,835)

Net increase (decrease) in cash, cash equivalents and restricted cash

258,446

(10,885)

Cash, cash equivalents and restricted cash, beginning of period

126,963

77,433

Cash, cash equivalents and restricted cash, end of period

385,409

66,548

Supplemental cash flow data:

Interest

37

48

Income taxes

944

821

Non-cash investing and financing activities:

Accrued purchases of long-lived assets

$ 5,337

$ 1,144

[1]	Adjusted to reflect the adoption of ASU 2016-18. See Note 1 for more information.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - Reconciliation of cash, cash equivalents and restricted cash - USD ($)
$ in Thousands

Jun. 30, 2018

Jun. 30, 2017

^[1]

Statement of Cash Flows [Abstract]

Cash and cash equivalents

$ 384,926

$ 66,086

Restricted cash included in other assets

483

462

Total cash, cash equivalents and restricted cash

$ 385,409

$ 66,548

[1]	Adjusted to reflect the adoption of ASU 2016-18. See Note 1 for more information.

Background and Basis of Presentation	6 Months Ended
Background and Basis of Presentation	Jun. 30, 2018
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 smarter way to student. As the leading direct-to-student learning platform, we strive to improve educational outcomes by putting the student first in all our decisions. We support students on their journey from high school to college and into their career with tools designed to help them pass their test, pass their class, and save money on required materials. Our services are available online, anytime and anywhere, so we can reach students when they need us most. Basis of Presentation The accompanying condensed consolidated balance sheet as of June 30, 2018, the condensed consolidated statements of operations and the condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2018 and 2017, the condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 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 June 30, 2018, our results of operations for the three and six months ended June 30, 2018 and 2017, and cash flows for the six months ended June 30, 2018 and 2017. Our results of operations and cash flows for the six months ended June 30, 2018 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, 2017 as 2017. 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, 2017 (the Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). We have changed the caption on our condensed consolidated statements of operations from “technology and development” to “research and development.” This change does not impact any current or previously reported amounts. Except for our policies on revenue recognition, deferred revenue and convertible senior notes, 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. Revenue Recognition and Deferred Revenue We recognize revenues from our Chegg Services and Required Materials offerings when control of the goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. We determine revenue recognition through the following steps: •Identification of the contract, or contracts, with a customer •Identification of the performance obligations in the contract •Determination of the transaction price •Allocation of the transaction price to the performance obligations in the contract •Recognition of revenue when, or as, we satisfy a performance obligation We generate revenues from our Chegg Services product line including our Chegg Study service, our Chegg Writing service, our Chegg Tutors service, Test Prep, through our partnership with Kaplan Test Prep (Kaplan), Internship services, Brand Partnership services that we offer to brands and Enrollment Marketing services to colleges, through our strategic partnership with the National Research Center for College and University Admissions (NRCCUA). Chegg Services are offered to students through weekly, monthly or annual subscriptions, and we primarily recognize revenues ratably over the respective subscription period. Enrollment Marketing services and Brand Partnership services are offered either on a subscription or on an a la carte basis. Revenues are recognized ratably or as earned over the subscription service period, generally one year. Revenues from Enrollment Marketing services or Brand Partnership services delivered on an a la carte basis, without a subscription, are recognized when delivery of the respective lead or service has occurred. Historically, under previous revenue recognition guidance, revenue recognition was delayed for certain contracts with extended payment terms. For these services, we bill the customer at the inception, over the term of the customer arrangement or as the services are performed. Upon satisfactory assessment of creditworthiness, we generally grant credit to our Enrollment Marketing and Brand Partnership customers with normal credit terms, typically 30 days. Some of our customer arrangements for Brand Partnership and Enrollment Marketing services include multiple performance obligations. We have determined these performance obligations qualify as distinct performance obligations, as the customer can benefit from the service on its own or together with other resources that are readily available to the customer and our promise to transfer the service is separately identifiable from other promises in the contract. For these arrangements that contain distinct performance obligations, we allocate the transaction price based on the relative standalone selling price method by comparing the standalone selling price (SSP) of each distinct performance obligation to the total value of the contract. We determine the SSP based on our historical pricing and discounting practices for the distinct performance obligation when sold separately. If the SSP is not directly observable, we estimate the SSP by considering information such as market conditions, and information about the customer. Additionally, we limit the amount of revenues recognized for delivered promises to the amount that is not contingent on future delivery of services or other future performance obligations. We also generate revenues from our Required Materials product line including revenue share earned on print textbooks for rental or sale transactions, owned by Ingram and other partners, which are recognized immediately when a book ships to the student. Revenues from the rental or sale of eTextbooks is recognized ratably over the contractual period, generally two to five months, or at time of the sale, respectively. Our strategic partnership with Ingram includes an amount of variable consideration in addition to a fixed revenue share that we earn. This variable consideration can either increase or decrease the total transaction price depending on the nature of the variable consideration. Under the new revenue recognition guidance, we estimate the amount of variable consideration that we will earn at the inception of the contract, adjusted during each period, and include an estimated amount each period as opposed to the contractual amount earned under the previous revenue recognition guidance. For sales of third party products, we evaluate whether we are acting as a principal or an agent, and therefore would record the gross sales amount as revenues and related costs or the net amount earned as a revenue share from the sale of third party products. Our determination is based on our evaluation of whether we control the specified goods or services prior to transferring them to the customer. For our strategic partnership with Ingram and our agreements with other textbook publishers, we have concluded that we do not control the use of the print textbooks, and therefore record net revenue only for the revenue share we earn upon the shipment of a print textbook to a student. For the sale of eTextbooks we have concluded that we control the service, therefore we recognize revenue and cost of revenue on a gross basis. Revenues are presented net of sales tax collected from customers to be remitted to governmental authorities and net of allowances for estimated cancellations and customer returns, which are based on historical data. Customer refunds from cancellations and returns are recorded as a reduction to revenues. Contract assets are contained within other current assets on our condensed consolidated balance sheets. Contract assets represent the goods or services that we have transferred to a customer before invoicing the customer. Contract receivables are contained within accounts receivable, net on our condensed consolidated balance sheets and represent unconditional consideration that will be received solely due to the passage of time. Contract liabilities are contained within deferred revenue on our condensed consolidated balance sheets. Deferred revenue primarily consists of advanced payments from students related to rentals and subscriptions performance obligations that have not been satisfied, and Brand Partnership and Enrollment Marketing performance obligations that have yet to be satisfied. Deferred revenue is recognized as revenues ratably over the term for subscriptions or when the services are provided and all other revenue recognition criteria have been met. Convertible Senior Notes, net In April 2018, we issued $345 million in aggregate principal amount of 0.25% convertible senior notes due in 2023 (the notes). In accounting for their issuance, we separated the notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of similar liabilities that do not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the carrying amount of the liability component from the par value of the notes. The difference represents the debt discount, recorded as a reduction of the convertible senior notes on our condensed consolidated balance sheet, and is amortized to interest expense over the term of the notes using the effective interest rate method. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. In accounting for the issuance costs related to the notes, we allocated the total amount of issuance costs incurred to liability and equity components based on their relative values. Issuance costs attributable to the liability component are being amortized on a straight-line basis, which approximates the effective interest rate method, to interest expense over the term of the notes. The issuance costs attributable to the equity component are recorded as a reduction of the equity component within additional paid-in capital. 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 including variable consideration, recoverability of accounts receivable, fair value of debt and equity components related to our convertible senior notes, restructuring charges, share-based compensation expense including estimated forfeitures, accounting for income taxes, useful lives assigned to long-lived assets for depreciation and amortization, valuation 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 Recently Issued Accounting Pronouncements Not Yet Adopted In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (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 beginning after December 15, 2018 and we plan to adopt the guidance on January 1, 2019. We plan to elect the package of transition practical expedients which include not reassessing whether any expired or existing contracts are or contain leases, not reassessing the lease classification of expired or existing leases, and not reassessing initial direct costs for existing leases. At this time, we do not know the quantitative impact of adopting ASU 2016-02; however, we initially believe that this will only have an impact on our consolidated balance sheet and little to no impact to our statement of operations. We will continue to evaluate as we near our adoption date. Recently Adopted Accounting Pronouncements In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. ASU 2018-07 expands the scope of Topic 718, Compensation—Stock Compensation to include share-based payment transactions for acquiring goods and services from non-employees. These awards are measured at the grant-date fair value of the equity instruments that an entity is obligated to issue when the good has been delivered or the service has been rendered and any other conditions necessary to earn the right to benefit from the instruments have been satisfied. The guidance is effective for annual periods after December 15, 2018, with early adoption permitted, and the guidance requires a modified retrospective application to awards that have not been settled as of the adoption date. We have elected to early adopt this guidance during the second quarter of 2018 and our adoption did not result in an adjustment to the opening balance of accumulated deficit. In February 2018, the FASB issued ASU No. 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. ASU 2018-02 allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. We adopted the guidance on January 1, 2018 recording an immaterial reclassification from accumulated other comprehensive income (loss) to the opening balance of accumulated deficit. 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. We early adopted the guidance with a prospective application on January 1, 2018 and will apply the guidance starting with our 2018 annual goodwill impairment assessment. 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. We adopted the guidance with a prospective application on January 1, 2018. We will analyze the clarified definition of a business to determine whether transactions from our application date should be accounted for as an asset acquisition or business combination under the new guidance. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. ASU 2016-18 requires an entity to explain the change during a period in restricted cash equivalents on the condensed consolidated statements of cash flows and include such amounts when reconciling beginning-of-period and end-of-period total amounts shown on the consolidated statements of cash flows. We adopted the guidance with a retrospective application on January 1, 2018 and have adjusted our beginning-of-period and end-of-period amounts on our condensed consolidated statement of cash flows to include restricted cash with the change in restricted cash included within the other assets line on our condensed consolidated statement of cash flows. In January 2016, the FASB issued ASU 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ASU 2016-01 requires entities to measure equity investments at fair value and recognize any changes in fair value within the statement of operations. We have a strategic investment of $3.0 million recorded in other assets on our condensed consolidated balance sheets that falls under this guidance update. The guidance provides for electing a measurement alternative for equity investments that do not have readily determinable fair values. We have elected the measurement alternative for our strategic investment as there is not a readily determinable fair value, which we will apply to our strategic investment starting with our adoption date of January 1, 2018. This investment will be measured at cost, less any impairment, plus or minus adjustments resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer, with any changes in the value of the investment recorded within the statement of operations. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, as amended (Topic 606) (ASC 606), which changes the way we recognize revenue and significantly expands the disclosure requirements for revenue arrangements. We adopted ASU 2014-09 under the modified retrospective application, recording the cumulative effect of adoption as an adjustment to the opening balance of accumulated deficit on our adoption date of January 1, 2018. We have not adjusted previously reported amounts. Adoption of the new standard resulted in changes to our accounting policies for revenue recognition, and trade and other receivables. See note 2 for more information.

Revenues

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Revenues

Adoption of ASC Topic 606, Revenue from Contracts with Customers

On January 1, 2018, we adopted the new revenue recognition guidance using the modified retrospective method applied to those contracts which were not completed as of January 1, 2018. Results for reporting periods beginning January 1, 2018 are presented under the new revenue recognition guidance, while prior period amounts were not adjusted and continue to be reported in accordance with the previous revenue recognition guidance.

We recorded an immaterial net increase to the opening balance of accumulated deficit as of January 1, 2018 due to the cumulative impact of adopting the new revenue recognition guidance. The two primary impacts of the new revenue recognition guidance are for our Enrollment Marketing services where revenue is recognized earlier in the contract life under the new revenue recognition guidance than under the previous guidance and for our strategic partnership with Ingram where we are required to estimate variable consideration under the new revenue recognition guidance, which we were not previously required to estimate. The requirement to estimate variable consideration has shifted $0.8 million and $1.1 million of revenues during the three and six months ended June 30, 2018, respectively, to future periods as compared to the previous revenue recognition guidance.

Revenue Recognition

Revenues are recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. The majority of our revenues are recognized over time as services are performed, with certain revenues, most significantly the revenue share we earn from Ingram and other partners, being recognized at the point in time when print textbooks are shipped to students.

The following table sets forth our total net revenues for the periods shown disaggregated for our Chegg Services and Required Materials product lines (in thousands, except percentages):



	Three Months Ended June 30,				Change
	2018		2017⁽¹⁾		$		%
Chegg Services	$	61,849	$	44,700	$	17,149	38	%
Required Materials	12,373		11,617		756		7	%
Total net revenues	$	74,222	$	56,317	$	17,905	32	%



	Six Months Ended June 30,				Change
	2018		2017⁽¹⁾		$			%
Chegg Services	$	118,126	$	85,735	$	32,391		38	%
Required Materials	33,045		33,184		(139		)	—	%
Total net revenues	$	151,171	$	118,919	$	32,252		27	%

⁽¹⁾ As noted above, prior period amounts have not been adjusted under the modified retrospective method.

During the three months ended June 30, 2018, we recognized $14.5 million of revenues that were included in our deferred revenue balance as of March 31, 2018. During the six months ended June 30, 2018, we recognized $11.2 million of revenues that were included in our deferred revenue balance as of December 31, 2017. During the three and six months ended June 30, 2018, there were no revenues recognized from performance obligations satisfied in previous periods. The aggregate amount of unsatisfied performance obligations is approximately $17.7 million as of June 30, 2018, of which a majority is expected to be recognized into revenues over the next year and the remainder within three years. As a practical expedient, we do not disclose the value of unsatisfied performance obligations for contracts with an expected duration of one year or less.

Contract Balances

The following table presents our accounts receivable, net and deferred revenue balances (in thousands, except percentages):



					Change
	June 30, 2018		December 31, 2017		$			%
Accounts receivable, net	$	8,096	$	10,855	$	(2,759	)	(25	)%
Deferred revenue	$	13,710	$	13,440	$	270		2	%

During the six months ended June 30, 2018, our accounts receivable, net balance decreased by $2.8 million, or 25%, primarily due to an improvement in cash collections. During the six months ended June 30, 2018, our deferred revenue balance increased by $0.3 million, or 2%, primarily due to increased bookings for our Chegg Study service and eTextbook rentals.

Our contract assets balance was immaterial as of June 30, 2018 and December 31, 2017.

Net Loss Per Share

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

Net Loss Per Share

Basic net loss per share is computed by dividing 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 June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Numerator:
Net loss	$	(3,909	)	$	(6,025	)	$	(6,526	)	$	(12,426	)
Denominator:
Weighted average shares used to compute net loss per share, basic and diluted	112,738			95,047			111,826			93,943

Net loss per share, basic and diluted	$	(0.03	)	$	(0.06	)	$	(0.06	)	$	(0.13	)

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 June 30,		Six Months Ended June 30,
	2018	2017	2018	2017
Options to purchase common stock	4,369	3,119	4,321	3,395
RSUs and PSUs	7,079	107	8,128	66
Employee stock purchase plan	—	8	—	8
Warrants to purchase common stock	—	200	—	200
Total common stock equivalents	11,448	3,434	12,449	3,669

Cash and Cash Equivalents, and Investment

6 Months Ended

Jun. 30, 2018

Cash and Cash Equivalents [Abstract]

Cash and Cash Equivalents, and Investment

Cash and Cash Equivalents, and Investments

The following table shows our cash and cash equivalents, and investments’ cost, net unrealized loss and fair value as of June 30, 2018 and December 31, 2017 (in thousands):



	June 30, 2018							December 31, 2017
	Cost		Net Unrealized Gain/(Loss)			Fair Value		Cost		Net Unrealized Loss			Fair Value
Cash and cash equivalents:
Cash	$	350,638	$	—		$	350,638	$	98,370	$	—		$	98,370
Money market funds	5,032		—			$	5,032	5,358		—			5,358
Commercial paper	29,252		4			29,256		22,729		—			22,729
Total cash and cash equivalents	$	384,922	$	4		$	384,926	$	126,457	$	—		$	126,457
Short-term investments:
Commercial paper	$	36,493	$	6		$	36,499	$	38,850	$	(27	)	$	38,823
Corporate securities	35,099		(118		)	34,981		23,001		(43		)	22,958
U.S. treasury securities	9,460		(2		)	9,458		19,978		(17		)	19,961
Total short-term investments	$	81,052	$	(114	)	$	80,938	$	81,829	$	(87	)	$	81,742
Long-term investments:
Corporate securities	$	14,389	$	(53	)	$	14,336	$	20,405	$	(100	)	$	20,305
U.S. treasury securities	1,622		(1		)	1,621		—		—			—
Total long-term investments	$	16,011	$	(54	)	$	15,957	$	20,405	$	(100	)	$	20,305

The cost and fair value of available-for-sale investments as of June 30, 2018 by contractual maturity were as follows (in thousands):



	Cost		Fair Value
Due in 1 year or less	$	110,304	$	110,194
Due in 1-2 years	16,011		15,957
Investments not due at a single maturity date	5,032		5,032
Total	$	131,347	$	131,183

Investments not due at a single maturity date in the preceding table consist of money market fund deposits.

As of June 30, 2018, 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 do not intend to sell the investments nor is it more likely than not that we will be required to sell the investments before recovery of their cost bases. We typically invest in highly-rated securities with a minimum credit rating of A- and a weighted average maturity of five 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 three months ended June 30, 2018 and 2017, we did not recognize any impairment charges.

Restricted Cash

As of June 30, 2018 and December 31, 2017, we had approximately $0.5 million of restricted cash that consists of security deposits for our offices. These amounts are classified in either other current assets and other assets on our condensed consolidated balance sheets based on the remaining term of the lease 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 an impairment charge on this investment during the three and six months ended June 30, 2018 and 2017, as there were no significant identified events or changes in circumstances that would be considered an indicator for impairment. Further, there were no observable price changes in orderly transactions for the identical or a similar investment of the same issuer during the three and six months ended June 30, 2018.

Fair Value Measurement

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

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 June 30, 2018 and December 31, 2017 are classified based on the valuation technique level in the tables below (in thousands):



	June 30, 2018
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents:
Money market funds	$	5,032	$	5,032	$	—
Commercial paper	29,256		—		29,256
Short-term investments:
Commercial paper	36,499		—		36,499
Corporate securities	34,981		—		34,981
U.S. treasury securities	9,458		9,458		—
Long-term investments:
Corporate securities	14,336		—		14,336
U.S. treasury securities	1,621		1,621		—
Total assets measured and recorded at fair value	$	131,183	$	16,111	$	115,072



	December 31, 2017
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents:
Money market funds	$	5,358	$	5,358	$	—
Commercial paper	22,729		—		22,729
Short-term investments:	—
Commercial paper	38,823		—		38,823
Corporate securities	22,958		—		22,958
U.S. treasury securities	19,961		19,961		—
Long-term corporate securities	20,305		—		20,305
Total assets measured and recorded at fair value	$	130,134	$	25,319	$	104,815

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. Other than our money market funds and U.S. treasury securities, we classify 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. We do not hold any marketable securities valued with a Level 3 input.

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.

Financial Instruments Not Recorded at Fair Value on a Recurring Basis

We report our financial instruments at fair value with the exception of the notes. The notes are measured at fair value on a quarterly basis for disclosure purposes.

The carrying amounts and estimated fair values of financial instruments not recorded at fair value as of June 30, 2018 are as follows (in thousands):



	June 30, 2018
	Carrying Amount		Estimated Fair Value
Convertible senior notes, net	$	276,578	$	413,569

The carrying amount of the notes as of June 30, 2018 was net of unamortized debt discount of $61.1 million and unamortized issuance costs of $7.3 million. The estimated fair value of the notes was determined based on the closing trading price of the notes as of the last day of trading for the period. We consider the fair value of the notes to be a Level 2 measurement due to the limited trading activity. For further information on the notes see Note 8.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Acquisition

6 Months Ended

Jun. 30, 2018

Business Combinations [Abstract]

Acquisition

On May 15, 2018, we acquired WriteLab, Inc. (WriteLab), an AI-enhanced writing platform, based in Berkeley, California, that teaches students grammar, sentence structure, writing style, and offers instant feedback to help students revise, edit, and improve their written work. This acquisition helps to strengthen our existing Chegg Writing service with the addition of new tools, features, and functionality. The total fair value of the purchase consideration was $14.5 million which included an escrow amount of $2.6 million for general representations and warranties and potential post-closing adjustments. Any remaining escrow amount will be released twenty months after the acquisition date.

The acquisition date fair value of the purchase consideration for the above transaction consisted of the following (in thousands):



Initial cash consideration	$	12,450
Escrow	2,550
Net working capital adjustment	(483		)
Fair value of purchase consideration	$	14,517

Included in the purchase agreement for the acquisition of WriteLab are additional contingent payments of up to $5.0 million subject to continued employment of the sellers. These payments are expensed ratably as research and development expenses on our condensed consolidated statement of operations. These contingent payments may be settled by us, at our sole discretion, either in cash or shares of our common stock. We have recorded approximately $0.2 million as of June 30, 2018 included within accrued liabilities on our condensed consolidated balance sheet for these contingent payments.

The fair value of the intangible assets acquired was determined under the acquisition method of accounting for business combinations. The excess of the purchase consideration paid over the fair value of net identifiable assets acquired was recorded as goodwill. Goodwill is primarily attributable to the potential for future product offerings as well as our expanded student reach. The amounts recorded for intangible assets and goodwill are not deductible for tax purposes.

The following table presents the total allocation of purchase consideration recorded in our condensed consolidated balance sheets as of the acquisition date (in thousands):



Cash	$	82
Accounts receivable	14
Acquired intangible assets:
Developed technology	4,450
Total identifiable assets acquired	4,546
Liabilities assumed	(826		)
Goodwill	10,797
Total fair value of purchase consideration	$	14,517

During the three months ended June 30, 2018, we incurred $0.4 million of acquisition-related expenses which have been included in general and administrative expenses in our condensed consolidated statement of operations.

We have not presented supplemental pro forma financial information as the revenues and earnings of WriteLab were immaterial during the six months ended June 30, 2018. Further, we have recorded no revenues and an immaterial amount of earnings from WriteLab since the acquisition date.

Goodwill and Intangible Assets

6 Months Ended

Jun. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets

Goodwill consists of the following (in thousands):



	Six Months Ended June 30, 2018			Year Ended December 31, 2017
Beginning balance	$	125,272		$	116,239
Additions due to acquisition	10,797			9,024
Foreign currency translation adjustment	(227		)	9
Ending balance	$	135,842		$	125,272

Intangible assets as of June 30, 2018 and December 31, 2017 consist of the following (in thousands, except the weighted-average amortization period in months):



	June 30, 2018
	Weighted-Average Amortization Period	Gross Carrying Amount			Accumulated Amortization			Net Carrying Amount
Developed technologies	74	$	25,107		$	(11,555	)	$	13,552
Customer lists	47	9,970			(6,163		)	3,807
Trade names	46	5,793			(4,214		)	1,579
Non-compete agreements	30	1,798			(1,602		)	196
Master service agreements	21	1,030			(1,030		)	—
Indefinite-lived trade name	—	3,600			—			3,600
Foreign currency translation adjustment	—	(143		)	—			(143		)
Total intangible assets	61	$	47,155		$	(24,564	)	$	22,591



	December 31, 2017
	Weighted-Average Amortization Period	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Developed technologies	70	$	20,657	$	(10,220	)	$	10,437
Customer lists	47	9,970		(5,480		)	4,490
Trade names	46	5,793		(3,465		)	2,328
Non-compete agreements	30	1,798		(1,506		)	292
Master service agreements	21	1,030		(1,030		)	—
Indefinite-lived trade name	—	3,600		—			3,600
Foreign currency translation adjustment	—	6		—			6
Total intangible assets	57	$	42,854	$	(21,701	)	$	21,153

During the three and six months ended June 30, 2018, amortization expense related to our acquired intangible assets totaled approximately $1.4 million and $2.9 million, respectively. During the three and six months ended June 30, 2017, amortization expense related to our acquired intangible assets totaled approximately $1.4 million and $2.8 million, respectively.

As of June 30, 2018, the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands):



Remaining six months of 2018	$	2,795
2019	4,903
2020	3,431
2021	2,074
2022	1,631
Thereafter	4,157
Total	$	18,991

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Convertible Senior Notes

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Convertible Senior Notes

In April 2018, we issued $345 million in aggregate principal amount of 0.25% convertible senior notes due in 2023 (the notes), in a private placement to qualified institutional buyers pursuant to Rule 144A of the Securities Act of 1933, as amended. The aggregate principal amount of the notes includes $45 million from initial purchasers fully exercising their option to purchase additional notes.

The total net proceeds from the notes are as follows (in thousands):



Principal amount	$	345,000
Less initial purchasers’ discount	(8,625		)
Less other issuance costs	(774		)
Net proceeds	$	335,601

The notes are our senior, unsecured obligations and bear interest of 0.25% per year which is payable semi-annually in arrears on May 15 and November 15 of each year, beginning on November 15, 2018. The notes will mature on May 15, 2023 (the maturity date), unless repurchased, redeemed or converted in accordance with their terms prior to such date. The terms of the notes are governed by an indenture agreement by and between us and Wells Fargo Bank, National Association, as Trustee (the indenture).

Each $1,000 principal amount of the notes will initially be convertible into 37.1051 shares of our common stock. This is equivalent to an initial conversion price of approximately $26.95 per share, which is subject to adjustment in certain circumstances. Prior to the close of business on the business day immediately preceding February 15, 2023, the notes are convertible at the option of holders only upon satisfaction of the following circumstances:

•

during any calendar quarter commencing after the calendar quarter ending on June 30, 2018, if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price for the notes on each applicable trading day;


•	during the five business day period after any ten consecutive trading day period (the measurement period) in which the trading price per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate on each such trading day;


•	if we call any or all of the notes for redemption, at any time prior to the close of business on the second scheduled trading day immediately preceding the redemption date; or


•	upon the occurrence of certain specified corporate events described in the indenture.

On or after February 15, 2023 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their notes at any time, regardless of the foregoing circumstances. Upon conversion, the notes may be settled in shares of our common stock, cash or a combination of cash and shares of our common stock, at our election.

If we undergo a fundamental change, as defined in the indenture, prior to the maturity date, subject to certain conditions, holders of the notes may require us to repurchase for cash all or any portion of their notes at a repurchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, if specific corporate events, described in the indenture, occur prior to the applicable maturity date, we will also increase the conversion rate for a holder who elects to convert their notes in connection with such specified corporate events. During the three months ended June 30, 2018, the conditions allowing holders of the notes to convert have not been met. The notes are therefore not convertible during the three months ended June 30, 2018 and are classified as long-term debt.

In accounting for the issuance of the notes, we separated the notes into liability and equity components. The carrying amount of the liability component of approximately $280.8 million was calculated by measuring the fair value of similar debt instruments that do not have an associated convertible feature. The carrying amount of the equity component of approximately $64.2 million, representing the conversion option, was determined by deducting the carrying amount of the liability component from the principal amount of the notes. This difference between the principal amount of the notes and the liability component represents the debt discount, presented as a reduction to the convertible debt on our condensed consolidated balance sheet, and is amortized to interest expense using the effective interest method over the remaining term of the notes. The equity component of the notes is included in additional paid-in capital on our consolidated balance sheet and is not remeasured as long as it continues to meet the conditions for equity classification.

We incurred issuance costs related to the notes of approximately $9.4 million, consisting of the initial purchasers' discount of $8.6 million and other issuance costs of approximately $0.8 million. In accounting for the issuance costs, we allocated the total amount incurred to the liability and equity components using the same proportions determined above for the principal amount of the notes. Transaction costs attributable to the liability component of approximately $7.7 million, were recorded as debt issuance cost, presented as a reduction to the convertible debt on our condensed consolidated balance sheet, and are amortized to interest expense using the effective interest method over the term of the notes. The issuance costs attributable to the equity component were approximately $1.7 million and were recorded as a reduction to the equity component included in additional paid-in capital.

The net carrying amount of the liability component of the notes is as follows (in thousands):



	As of June 30, 2018
Principal	$	345,000
Unamortized debt discount	(61,136		)
Unamortized issuance costs	(7,286		)
Net carrying amount	$	276,578

The net carrying amount of the equity component of the notes is as follows (in thousands):



	As of June 30, 2018
Debt discount for conversion option	$	64,193
Issuance costs	(1,749		)
Net carrying amount	$	62,444

As of June 30, 2018, the remaining life of the notes is approximately 4.9 years.

Based on the closing price of our common stock of $27.79 on June 30, 2018, the if-converted value of the notes was approximately $355.7 million and exceeds the principal amount of $345 million by approximately $10.7 million.

The effective interest rate of the liability component of the notes is 4.34% and is based on the interest rate of similar debt instruments that do not have an associated convertible feature. The following table sets forth the total interest expense recognized related to the notes (in thousands):



	Three Months Ended June 30, 2018
Contractual interest expense	$	210
Amortization of debt discount	3,057
Amortization of issuance costs	364
Total interest expense	$	3,631

Capped Call Transactions

Concurrently with the offering of the notes in April 2018, we used $39.2 million of the net proceeds to enter into privately negotiated capped call transactions which are expected to generally reduce or offset potential dilution to holders of our common stock upon conversion of the notes and/or offset the potential cash payments we would be required to make in excess of the principal amount of any converted notes. The capped call transactions cover approximately 12,801,260 shares of our common stock and are intended to effectively increase the overall conversion price from $26.95 to $40.68 per share. As these transactions meet certain accounting criteria, they are recorded in stockholders’ equity as a reduction of additional paid-in capital on our condensed consolidated balance sheet and are not accounted for as derivatives. The fair value of the capped call instrument is not remeasured each reporting period. The cost of the capped call is not expected to be deductible for tax purposes.

Impact to Earnings per Share

The notes will have no impact to diluted earnings per share until the average price of Chegg’s common stock exceeds the conversion price of $26.95 per share because we intend to settle the principal amount of the notes in cash upon conversion. Under the treasury stock method, in periods we report net income, we are required to include the effect of additional shares that may be issued under the notes when the average price of our common stock exceeds the conversion price. However, as a result of the capped call transactions described above, there will be no economic dilution from the notes up to $40.68, as exercise of the capped call instruments will reduce any dilution from the notes that would have otherwise occurred when the price of our common stock exceeds the conversion price.

Revolving Line of Credit

In September 2016, we entered into a revolving line of credit, which was amended in March 2018, 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. The Line of Credit expires in 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 and amortized debt issuance costs, 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 June 30, 2018, 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.

Revolving Line of Credit

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Revolving Line of Credit

Convertible Senior Notes

In April 2018, we issued $345 million in aggregate principal amount of 0.25% convertible senior notes due in 2023 (the notes), in a private placement to qualified institutional buyers pursuant to Rule 144A of the Securities Act of 1933, as amended. The aggregate principal amount of the notes includes $45 million from initial purchasers fully exercising their option to purchase additional notes.

The total net proceeds from the notes are as follows (in thousands):



Principal amount	$	345,000
Less initial purchasers’ discount	(8,625		)
Less other issuance costs	(774		)
Net proceeds	$	335,601

The notes are our senior, unsecured obligations and bear interest of 0.25% per year which is payable semi-annually in arrears on May 15 and November 15 of each year, beginning on November 15, 2018. The notes will mature on May 15, 2023 (the maturity date), unless repurchased, redeemed or converted in accordance with their terms prior to such date. The terms of the notes are governed by an indenture agreement by and between us and Wells Fargo Bank, National Association, as Trustee (the indenture).

Each $1,000 principal amount of the notes will initially be convertible into 37.1051 shares of our common stock. This is equivalent to an initial conversion price of approximately $26.95 per share, which is subject to adjustment in certain circumstances. Prior to the close of business on the business day immediately preceding February 15, 2023, the notes are convertible at the option of holders only upon satisfaction of the following circumstances:

•

during any calendar quarter commencing after the calendar quarter ending on June 30, 2018, if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price for the notes on each applicable trading day;


•	during the five business day period after any ten consecutive trading day period (the measurement period) in which the trading price per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate on each such trading day;


•	if we call any or all of the notes for redemption, at any time prior to the close of business on the second scheduled trading day immediately preceding the redemption date; or


•	upon the occurrence of certain specified corporate events described in the indenture.

On or after February 15, 2023 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their notes at any time, regardless of the foregoing circumstances. Upon conversion, the notes may be settled in shares of our common stock, cash or a combination of cash and shares of our common stock, at our election.

If we undergo a fundamental change, as defined in the indenture, prior to the maturity date, subject to certain conditions, holders of the notes may require us to repurchase for cash all or any portion of their notes at a repurchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, if specific corporate events, described in the indenture, occur prior to the applicable maturity date, we will also increase the conversion rate for a holder who elects to convert their notes in connection with such specified corporate events. During the three months ended June 30, 2018, the conditions allowing holders of the notes to convert have not been met. The notes are therefore not convertible during the three months ended June 30, 2018 and are classified as long-term debt.

In accounting for the issuance of the notes, we separated the notes into liability and equity components. The carrying amount of the liability component of approximately $280.8 million was calculated by measuring the fair value of similar debt instruments that do not have an associated convertible feature. The carrying amount of the equity component of approximately $64.2 million, representing the conversion option, was determined by deducting the carrying amount of the liability component from the principal amount of the notes. This difference between the principal amount of the notes and the liability component represents the debt discount, presented as a reduction to the convertible debt on our condensed consolidated balance sheet, and is amortized to interest expense using the effective interest method over the remaining term of the notes. The equity component of the notes is included in additional paid-in capital on our consolidated balance sheet and is not remeasured as long as it continues to meet the conditions for equity classification.

We incurred issuance costs related to the notes of approximately $9.4 million, consisting of the initial purchasers' discount of $8.6 million and other issuance costs of approximately $0.8 million. In accounting for the issuance costs, we allocated the total amount incurred to the liability and equity components using the same proportions determined above for the principal amount of the notes. Transaction costs attributable to the liability component of approximately $7.7 million, were recorded as debt issuance cost, presented as a reduction to the convertible debt on our condensed consolidated balance sheet, and are amortized to interest expense using the effective interest method over the term of the notes. The issuance costs attributable to the equity component were approximately $1.7 million and were recorded as a reduction to the equity component included in additional paid-in capital.

The net carrying amount of the liability component of the notes is as follows (in thousands):



	As of June 30, 2018
Principal	$	345,000
Unamortized debt discount	(61,136		)
Unamortized issuance costs	(7,286		)
Net carrying amount	$	276,578

The net carrying amount of the equity component of the notes is as follows (in thousands):



	As of June 30, 2018
Debt discount for conversion option	$	64,193
Issuance costs	(1,749		)
Net carrying amount	$	62,444

As of June 30, 2018, the remaining life of the notes is approximately 4.9 years.

Based on the closing price of our common stock of $27.79 on June 30, 2018, the if-converted value of the notes was approximately $355.7 million and exceeds the principal amount of $345 million by approximately $10.7 million.

The effective interest rate of the liability component of the notes is 4.34% and is based on the interest rate of similar debt instruments that do not have an associated convertible feature. The following table sets forth the total interest expense recognized related to the notes (in thousands):



	Three Months Ended June 30, 2018
Contractual interest expense	$	210
Amortization of debt discount	3,057
Amortization of issuance costs	364
Total interest expense	$	3,631

Capped Call Transactions

Concurrently with the offering of the notes in April 2018, we used $39.2 million of the net proceeds to enter into privately negotiated capped call transactions which are expected to generally reduce or offset potential dilution to holders of our common stock upon conversion of the notes and/or offset the potential cash payments we would be required to make in excess of the principal amount of any converted notes. The capped call transactions cover approximately 12,801,260 shares of our common stock and are intended to effectively increase the overall conversion price from $26.95 to $40.68 per share. As these transactions meet certain accounting criteria, they are recorded in stockholders’ equity as a reduction of additional paid-in capital on our condensed consolidated balance sheet and are not accounted for as derivatives. The fair value of the capped call instrument is not remeasured each reporting period. The cost of the capped call is not expected to be deductible for tax purposes.

Impact to Earnings per Share

The notes will have no impact to diluted earnings per share until the average price of Chegg’s common stock exceeds the conversion price of $26.95 per share because we intend to settle the principal amount of the notes in cash upon conversion. Under the treasury stock method, in periods we report net income, we are required to include the effect of additional shares that may be issued under the notes when the average price of our common stock exceeds the conversion price. However, as a result of the capped call transactions described above, there will be no economic dilution from the notes up to $40.68, as exercise of the capped call instruments will reduce any dilution from the notes that would have otherwise occurred when the price of our common stock exceeds the conversion price.

Revolving Line of Credit

In September 2016, we entered into a revolving line of credit, which was amended in March 2018, 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. The Line of Credit expires in 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 and amortized debt issuance costs, 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 June 30, 2018, 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	6 Months Ended
Commitments and Contingencies	Jun. 30, 2018
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 June 30, 2018 are related to our corporate headquarters in Santa Clara, California. We have additional offices in California, Oregon and New York in the United States and internationally in India, Israel and Berlin. 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 $0.7 million and $1.4 million during the three and six months ended June 30, 2018, respectively and approximately $0.7 million and $1.4 million during the three and six months ended June 30, 2017, 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	6 Months Ended
Guarantees and Indemnifications	Jun. 30, 2018
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 immaterial. We have not recorded any liabilities for these agreements as of June 30, 2018.

Stockholders' Equity

6 Months Ended

Jun. 30, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stockholders' Equity

During the three months ended June 30, 2018, we repurchased 983,284 shares of our common stock at an average price per share of $20.34 in conjunction with our April 2018 offering of the notes.

Share-based Compensation Expense

Total share-based compensation expense recorded for employees and non-employees, is as follows (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Cost of revenues	$	103	$	88	$	197	$	155
Research and development	3,529		3,387		7,662		6,628
Sales and marketing	1,730		1,201		3,319		2,327
General and administrative	6,681		4,423		12,507		8,267
Total share-based compensation expense	$	12,043	$	9,099	$	23,685	$	17,377

There was no capitalized share-based compensation expense as of June 30, 2018 or 2017.

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, 2017	14,335,115		$	6.78
Granted	3,004,611		20.16
Released	(4,784,787	)	6.34
Canceled	(1,337,685	)	6.27
Balance at June 30, 2018	11,217,254		$	10.62

As of June 30, 2018, our total unrecognized share-based compensation expense related to RSUs and PSUs was approximately $76.5 million, which will be recognized over the remaining weighted-average vesting period of approximately 1.8 years.

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We recorded an income tax provision of approximately $0.4 million and $1.0 million during the three and six months ended June 30, 2018, respectively, primarily due to federal and state tax benefit related to deferred tax liabilities of acquired intangible assets. We recorded an income tax provision of approximately $0.7 million and $1.4 million during the three and six months ended June 30, 2017, respectively, primarily due to state and foreign income tax expense and federal tax expense related to acquired indefinite lived intangible assets. On December 22, 2017, Staff Accounting Bulletin No. 118 (SAB 118) was issued to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed in reasonable detail to complete the accounting for certain income tax effects of the Tax Cuts and Jobs Act (Tax Act). In accordance with SAB 118, as of June 30, 2018, we had not yet completed our accounting for the tax effects of the enactment of the Tax Act. Our estimate of the effects the Tax Act have not materially changed from the amounts recorded during the year ended December 31, 2017. We will continue to analyze certain aspects of the Tax Act and the newly issued Internal Revenue Service notifications and we expect future notices may continue to impact and refine our estimates.

Restructuring Charges

6 Months Ended

Jun. 30, 2018

Restructuring and Related Activities [Abstract]

Restructuring Charges

2017 Restructuring Plan

In January 2017, we entered into a strategic partnership with NRCCUA where they 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. Costs incurred to date are expected to be fully paid within 3 months.

2015 Restructuring Plan

Restructuring charges of $0.2 million recorded during the six months ended June 30, 2018 primarily related to our subtenant filing for bankruptcy and exiting our leased office. Costs incurred to date 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, 2017	$	—		$	—		$	—	$	306		$	306
Restructuring charges (credits)	941			148			—		(42		)	1,047
Cash payments	(897		)	(128		)	—		(43		)	(1,068		)
Write-offs	—			(20		)	—		—			(20		)
Balance at December 31, 2017	44			—			—		221			265
Restructuring charges	46			10			—		179			235
Cash payments	(42		)	(10		)	—		(112		)	(164		)
Write-offs	—			—			—		(18		)	(18		)
Balance at June 30, 2018	$	48		$	—		$	—	$	270		$	318

As of June 30, 2018, the $0.3 million liability was comprised of a short-term accrual of $0.2 million included within accrued liabilities and a long-term accrual of $0.1 million included within other liabilities on our condensed consolidated balance sheet.

Related-Party Transactions	6 Months Ended
Related-Party Transactions	Jun. 30, 2018
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 six months ended June 30, 2018, we had purchases of $0.6 million and $2.3 million, respectively, and during the three and six months ended June 30, 2017, we had purchases of $1.3 million and $1.8 million, respectively, from Adobe. We had no revenues during the three months ended June 30, 2018 and $0.1 million of revenues during the six months ended June 30, 2018 from Adobe. We had no revenues during the three and six months ended June 30, 2017 from Adobe. We had $0.3 million in payables as of June 30, 2018 and December 31, 2017 to Adobe. We had no accounts receivables as of June 30, 2018 and an immaterial amount of accounts receivable as of December 31, 2017 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 six months ended June 30, 2018, we had purchases of $1.4 million and $6.5 million, respectively, and during the three and six months ended June 30, 2017, we had purchases of $1.3 million and $4.8 million, respectively, from Cengage. We had $0.1 million and $2.0 million of revenues during the three and six months ended June 30, 2018, respectively, and $0.2 million and $0.6 million of revenues during the three and six months ended June 30, 2017, respectively, from Cengage. We had $0.9 million and $0.1 million in payables as of June 30, 2018 and December 31, 2017, respectively, to Cengage. We had no outstanding receivables as of June 30, 2018 and $0.3 million in outstanding receivables as of December 31, 2017 from Cengage. 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 six months ended June 30, 2018, we incurred payment processing fees of $0.2 million and $0.6 million, respectively, and during the three and six months ended June 30, 2017, we incurred payment processing fees of $0.2 million and $0.5 million, respectively, to PayPal.

Subsequent Event	6 Months Ended
Subsequent Event	Jun. 30, 2018
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event Acquisition of StudyBlue, Inc. On July 2, 2018, we acquired StudyBlue, Inc. (StudyBlue), a privately held online learning company based in San Francisco, California that provides a vast content library and tools for students to create their own study materials. Pursuant to the terms of the agreement, we paid $20.8 million in cash to the sellers at the closing of the acquisition. The initial accounting for this acquisition is in process as of the issuance date for our financial statements and therefore we are unable to make any additional disclosures.

Background and Basis of Presentation (Policies)	6 Months Ended
Background and Basis of Presentation (Policies)	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated balance sheet as of June 30, 2018, the condensed consolidated statements of operations and the condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2018 and 2017, the condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 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 June 30, 2018, our results of operations for the three and six months ended June 30, 2018 and 2017, and cash flows for the six months ended June 30, 2018 and 2017. Our results of operations and cash flows for the six months ended June 30, 2018 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, 2017 as 2017. 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, 2017 (the Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). We have changed the caption on our condensed consolidated statements of operations from “technology and development” to “research and development.” This change does not impact any current or previously reported amounts. Except for our policies on revenue recognition, deferred revenue and convertible senior notes, 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.
Revenue Recognition and Deferred Revenue	Revenue Recognition and Deferred Revenue We recognize revenues from our Chegg Services and Required Materials offerings when control of the goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. We determine revenue recognition through the following steps: •Identification of the contract, or contracts, with a customer •Identification of the performance obligations in the contract •Determination of the transaction price •Allocation of the transaction price to the performance obligations in the contract •Recognition of revenue when, or as, we satisfy a performance obligation We generate revenues from our Chegg Services product line including our Chegg Study service, our Chegg Writing service, our Chegg Tutors service, Test Prep, through our partnership with Kaplan Test Prep (Kaplan), Internship services, Brand Partnership services that we offer to brands and Enrollment Marketing services to colleges, through our strategic partnership with the National Research Center for College and University Admissions (NRCCUA). Chegg Services are offered to students through weekly, monthly or annual subscriptions, and we primarily recognize revenues ratably over the respective subscription period. Enrollment Marketing services and Brand Partnership services are offered either on a subscription or on an a la carte basis. Revenues are recognized ratably or as earned over the subscription service period, generally one year. Revenues from Enrollment Marketing services or Brand Partnership services delivered on an a la carte basis, without a subscription, are recognized when delivery of the respective lead or service has occurred. Historically, under previous revenue recognition guidance, revenue recognition was delayed for certain contracts with extended payment terms. For these services, we bill the customer at the inception, over the term of the customer arrangement or as the services are performed. Upon satisfactory assessment of creditworthiness, we generally grant credit to our Enrollment Marketing and Brand Partnership customers with normal credit terms, typically 30 days. Some of our customer arrangements for Brand Partnership and Enrollment Marketing services include multiple performance obligations. We have determined these performance obligations qualify as distinct performance obligations, as the customer can benefit from the service on its own or together with other resources that are readily available to the customer and our promise to transfer the service is separately identifiable from other promises in the contract. For these arrangements that contain distinct performance obligations, we allocate the transaction price based on the relative standalone selling price method by comparing the standalone selling price (SSP) of each distinct performance obligation to the total value of the contract. We determine the SSP based on our historical pricing and discounting practices for the distinct performance obligation when sold separately. If the SSP is not directly observable, we estimate the SSP by considering information such as market conditions, and information about the customer. Additionally, we limit the amount of revenues recognized for delivered promises to the amount that is not contingent on future delivery of services or other future performance obligations. We also generate revenues from our Required Materials product line including revenue share earned on print textbooks for rental or sale transactions, owned by Ingram and other partners, which are recognized immediately when a book ships to the student. Revenues from the rental or sale of eTextbooks is recognized ratably over the contractual period, generally two to five months, or at time of the sale, respectively. Our strategic partnership with Ingram includes an amount of variable consideration in addition to a fixed revenue share that we earn. This variable consideration can either increase or decrease the total transaction price depending on the nature of the variable consideration. Under the new revenue recognition guidance, we estimate the amount of variable consideration that we will earn at the inception of the contract, adjusted during each period, and include an estimated amount each period as opposed to the contractual amount earned under the previous revenue recognition guidance. For sales of third party products, we evaluate whether we are acting as a principal or an agent, and therefore would record the gross sales amount as revenues and related costs or the net amount earned as a revenue share from the sale of third party products. Our determination is based on our evaluation of whether we control the specified goods or services prior to transferring them to the customer. For our strategic partnership with Ingram and our agreements with other textbook publishers, we have concluded that we do not control the use of the print textbooks, and therefore record net revenue only for the revenue share we earn upon the shipment of a print textbook to a student. For the sale of eTextbooks we have concluded that we control the service, therefore we recognize revenue and cost of revenue on a gross basis. Revenues are presented net of sales tax collected from customers to be remitted to governmental authorities and net of allowances for estimated cancellations and customer returns, which are based on historical data. Customer refunds from cancellations and returns are recorded as a reduction to revenues. Contract assets are contained within other current assets on our condensed consolidated balance sheets. Contract assets represent the goods or services that we have transferred to a customer before invoicing the customer. Contract receivables are contained within accounts receivable, net on our condensed consolidated balance sheets and represent unconditional consideration that will be received solely due to the passage of time. Contract liabilities are contained within deferred revenue on our condensed consolidated balance sheets. Deferred revenue primarily consists of advanced payments from students related to rentals and subscriptions performance obligations that have not been satisfied, and Brand Partnership and Enrollment Marketing performance obligations that have yet to be satisfied. Deferred revenue is recognized as revenues ratably over the term for subscriptions or when the services are provided and all other revenue recognition criteria have been met.
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 including variable consideration, recoverability of accounts receivable, fair value of debt and equity components related to our convertible senior notes, restructuring charges, share-based compensation expense including estimated forfeitures, accounting for income taxes, useful lives assigned to long-lived assets for depreciation and amortization, valuation 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 Recently Issued Accounting Pronouncements Not Yet Adopted In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (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 beginning after December 15, 2018 and we plan to adopt the guidance on January 1, 2019. We plan to elect the package of transition practical expedients which include not reassessing whether any expired or existing contracts are or contain leases, not reassessing the lease classification of expired or existing leases, and not reassessing initial direct costs for existing leases. At this time, we do not know the quantitative impact of adopting ASU 2016-02; however, we initially believe that this will only have an impact on our consolidated balance sheet and little to no impact to our statement of operations. We will continue to evaluate as we near our adoption date. Recently Adopted Accounting Pronouncements In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. ASU 2018-07 expands the scope of Topic 718, Compensation—Stock Compensation to include share-based payment transactions for acquiring goods and services from non-employees. These awards are measured at the grant-date fair value of the equity instruments that an entity is obligated to issue when the good has been delivered or the service has been rendered and any other conditions necessary to earn the right to benefit from the instruments have been satisfied. The guidance is effective for annual periods after December 15, 2018, with early adoption permitted, and the guidance requires a modified retrospective application to awards that have not been settled as of the adoption date. We have elected to early adopt this guidance during the second quarter of 2018 and our adoption did not result in an adjustment to the opening balance of accumulated deficit. In February 2018, the FASB issued ASU No. 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. ASU 2018-02 allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. We adopted the guidance on January 1, 2018 recording an immaterial reclassification from accumulated other comprehensive income (loss) to the opening balance of accumulated deficit. 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. We early adopted the guidance with a prospective application on January 1, 2018 and will apply the guidance starting with our 2018 annual goodwill impairment assessment. 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. We adopted the guidance with a prospective application on January 1, 2018. We will analyze the clarified definition of a business to determine whether transactions from our application date should be accounted for as an asset acquisition or business combination under the new guidance. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. ASU 2016-18 requires an entity to explain the change during a period in restricted cash equivalents on the condensed consolidated statements of cash flows and include such amounts when reconciling beginning-of-period and end-of-period total amounts shown on the consolidated statements of cash flows. We adopted the guidance with a retrospective application on January 1, 2018 and have adjusted our beginning-of-period and end-of-period amounts on our condensed consolidated statement of cash flows to include restricted cash with the change in restricted cash included within the other assets line on our condensed consolidated statement of cash flows. In January 2016, the FASB issued ASU 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. ASU 2016-01 requires entities to measure equity investments at fair value and recognize any changes in fair value within the statement of operations. We have a strategic investment of $3.0 million recorded in other assets on our condensed consolidated balance sheets that falls under this guidance update. The guidance provides for electing a measurement alternative for equity investments that do not have readily determinable fair values. We have elected the measurement alternative for our strategic investment as there is not a readily determinable fair value, which we will apply to our strategic investment starting with our adoption date of January 1, 2018. This investment will be measured at cost, less any impairment, plus or minus adjustments resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer, with any changes in the value of the investment recorded within the statement of operations. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, as amended (Topic 606) (ASC 606), which changes the way we recognize revenue and significantly expands the disclosure requirements for revenue arrangements. We adopted ASU 2014-09 under the modified retrospective application, recording the cumulative effect of adoption as an adjustment to the opening balance of accumulated deficit on our adoption date of January 1, 2018. We have not adjusted previously reported amounts. Adoption of the new standard resulted in changes to our accounting policies for revenue recognition, and trade and other receivables. See note 2 for more information.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing 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.

Revenues (Tables)

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table sets forth our total net revenues for the periods shown disaggregated for our Chegg Services and Required Materials product lines (in thousands, except percentages):



	Three Months Ended June 30,				Change
	2018		2017⁽¹⁾		$		%
Chegg Services	$	61,849	$	44,700	$	17,149	38	%
Required Materials	12,373		11,617		756		7	%
Total net revenues	$	74,222	$	56,317	$	17,905	32	%



	Six Months Ended June 30,				Change
	2018		2017⁽¹⁾		$			%
Chegg Services	$	118,126	$	85,735	$	32,391		38	%
Required Materials	33,045		33,184		(139		)	—	%
Total net revenues	$	151,171	$	118,919	$	32,252		27	%

⁽¹⁾ As noted above, prior period amounts have not been adjusted under the modified retrospective method.

Schedule of Accounts Receivable

The following table presents our accounts receivable, net and deferred revenue balances (in thousands, except percentages):



					Change
	June 30, 2018		December 31, 2017		$			%
Accounts receivable, net	$	8,096	$	10,855	$	(2,759	)	(25	)%
Deferred revenue	$	13,710	$	13,440	$	270		2	%

Net Loss Per Share (Tables)

6 Months Ended

Jun. 30, 2018

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 June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Numerator:
Net loss	$	(3,909	)	$	(6,025	)	$	(6,526	)	$	(12,426	)
Denominator:
Weighted average shares used to compute net loss per share, basic and diluted	112,738			95,047			111,826			93,943

Net loss per share, basic and diluted	$	(0.03	)	$	(0.06	)	$	(0.06	)	$	(0.13	)

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 June 30,		Six Months Ended June 30,
	2018	2017	2018	2017
Options to purchase common stock	4,369	3,119	4,321	3,395
RSUs and PSUs	7,079	107	8,128	66
Employee stock purchase plan	—	8	—	8
Warrants to purchase common stock	—	200	—	200
Total common stock equivalents	11,448	3,434	12,449	3,669

Cash and Cash Equivalents, and Investment (Tables)

6 Months Ended

Jun. 30, 2018

Cash and Cash Equivalents [Abstract]

Cash, Cash Equivalents and Investments

The following table shows our cash and cash equivalents, and investments’ cost, net unrealized loss and fair value as of June 30, 2018 and December 31, 2017 (in thousands):



	June 30, 2018							December 31, 2017
	Cost		Net Unrealized Gain/(Loss)			Fair Value		Cost		Net Unrealized Loss			Fair Value
Cash and cash equivalents:
Cash	$	350,638	$	—		$	350,638	$	98,370	$	—		$	98,370
Money market funds	5,032		—			$	5,032	5,358		—			5,358
Commercial paper	29,252		4			29,256		22,729		—			22,729
Total cash and cash equivalents	$	384,922	$	4		$	384,926	$	126,457	$	—		$	126,457
Short-term investments:
Commercial paper	$	36,493	$	6		$	36,499	$	38,850	$	(27	)	$	38,823
Corporate securities	35,099		(118		)	34,981		23,001		(43		)	22,958
U.S. treasury securities	9,460		(2		)	9,458		19,978		(17		)	19,961
Total short-term investments	$	81,052	$	(114	)	$	80,938	$	81,829	$	(87	)	$	81,742
Long-term investments:
Corporate securities	$	14,389	$	(53	)	$	14,336	$	20,405	$	(100	)	$	20,305
U.S. treasury securities	1,622		(1		)	1,621		—		—			—
Total long-term investments	$	16,011	$	(54	)	$	15,957	$	20,405	$	(100	)	$	20,305

Schedule of Available-for-sale Securities Reconciliation

The cost and fair value of available-for-sale investments as of June 30, 2018 by contractual maturity were as follows (in thousands):



	Cost		Fair Value
Due in 1 year or less	$	110,304	$	110,194
Due in 1-2 years	16,011		15,957
Investments not due at a single maturity date	5,032		5,032
Total	$	131,347	$	131,183

Fair Value Measurement (Tables)

6 Months Ended

Jun. 30, 2018

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 June 30, 2018 and December 31, 2017 are classified based on the valuation technique level in the tables below (in thousands):



	June 30, 2018
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents:
Money market funds	$	5,032	$	5,032	$	—
Commercial paper	29,256		—		29,256
Short-term investments:
Commercial paper	36,499		—		36,499
Corporate securities	34,981		—		34,981
U.S. treasury securities	9,458		9,458		—
Long-term investments:
Corporate securities	14,336		—		14,336
U.S. treasury securities	1,621		1,621		—
Total assets measured and recorded at fair value	$	131,183	$	16,111	$	115,072



	December 31, 2017
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Assets:
Cash equivalents:
Money market funds	$	5,358	$	5,358	$	—
Commercial paper	22,729		—		22,729
Short-term investments:	—
Commercial paper	38,823		—		38,823
Corporate securities	22,958		—		22,958
U.S. treasury securities	19,961		19,961		—
Long-term corporate securities	20,305		—		20,305
Total assets measured and recorded at fair value	$	130,134	$	25,319	$	104,815

Fair Value Measurements, Nonrecurring

The carrying amounts and estimated fair values of financial instruments not recorded at fair value as of June 30, 2018 are as follows (in thousands):



	June 30, 2018
	Carrying Amount		Estimated Fair Value
Convertible senior notes, net	$	276,578	$	413,569

Acquisition (Tables)

6 Months Ended

Jun. 30, 2018

Business Combinations [Abstract]

Schedule Of Fair Value Of Consideration

The acquisition date fair value of the purchase consideration for the above transaction consisted of the following (in thousands):



Initial cash consideration	$	12,450
Escrow	2,550
Net working capital adjustment	(483		)
Fair value of purchase consideration	$	14,517

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed

The following table presents the total allocation of purchase consideration recorded in our condensed consolidated balance sheets as of the acquisition date (in thousands):



Cash	$	82
Accounts receivable	14
Acquired intangible assets:
Developed technology	4,450
Total identifiable assets acquired	4,546
Liabilities assumed	(826		)
Goodwill	10,797
Total fair value of purchase consideration	$	14,517

Goodwill and Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

Goodwill consists of the following (in thousands):



	Six Months Ended June 30, 2018			Year Ended December 31, 2017
Beginning balance	$	125,272		$	116,239
Additions due to acquisition	10,797			9,024
Foreign currency translation adjustment	(227		)	9
Ending balance	$	135,842		$	125,272

Finite-Lived Intangible Assets

Intangible assets as of June 30, 2018 and December 31, 2017 consist of the following (in thousands, except the weighted-average amortization period in months):



	June 30, 2018
	Weighted-Average Amortization Period	Gross Carrying Amount			Accumulated Amortization			Net Carrying Amount
Developed technologies	74	$	25,107		$	(11,555	)	$	13,552
Customer lists	47	9,970			(6,163		)	3,807
Trade names	46	5,793			(4,214		)	1,579
Non-compete agreements	30	1,798			(1,602		)	196
Master service agreements	21	1,030			(1,030		)	—
Indefinite-lived trade name	—	3,600			—			3,600
Foreign currency translation adjustment	—	(143		)	—			(143		)
Total intangible assets	61	$	47,155		$	(24,564	)	$	22,591



	December 31, 2017
	Weighted-Average Amortization Period	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Developed technologies	70	$	20,657	$	(10,220	)	$	10,437
Customer lists	47	9,970		(5,480		)	4,490
Trade names	46	5,793		(3,465		)	2,328
Non-compete agreements	30	1,798		(1,506		)	292
Master service agreements	21	1,030		(1,030		)	—
Indefinite-lived trade name	—	3,600		—			3,600
Foreign currency translation adjustment	—	6		—			6
Total intangible assets	57	$	42,854	$	(21,701	)	$	21,153

Indefinite-lived Intangible Assets

Intangible assets as of June 30, 2018 and December 31, 2017 consist of the following (in thousands, except the weighted-average amortization period in months):



	June 30, 2018
	Weighted-Average Amortization Period	Gross Carrying Amount			Accumulated Amortization			Net Carrying Amount
Developed technologies	74	$	25,107		$	(11,555	)	$	13,552
Customer lists	47	9,970			(6,163		)	3,807
Trade names	46	5,793			(4,214		)	1,579
Non-compete agreements	30	1,798			(1,602		)	196
Master service agreements	21	1,030			(1,030		)	—
Indefinite-lived trade name	—	3,600			—			3,600
Foreign currency translation adjustment	—	(143		)	—			(143		)
Total intangible assets	61	$	47,155		$	(24,564	)	$	22,591



	December 31, 2017
	Weighted-Average Amortization Period	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Developed technologies	70	$	20,657	$	(10,220	)	$	10,437
Customer lists	47	9,970		(5,480		)	4,490
Trade names	46	5,793		(3,465		)	2,328
Non-compete agreements	30	1,798		(1,506		)	292
Master service agreements	21	1,030		(1,030		)	—
Indefinite-lived trade name	—	3,600		—			3,600
Foreign currency translation adjustment	—	6		—			6
Total intangible assets	57	$	42,854	$	(21,701	)	$	21,153

Estimated Future Amortization Expense Related to Intangible Assets

As of June 30, 2018, the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands):



Remaining six months of 2018	$	2,795
2019	4,903
2020	3,431
2021	2,074
2022	1,631
Thereafter	4,157
Total	$	18,991

Convertible Senior Notes (Tables)

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Schedule Of Net Proceeds From Debt Issuance

The total net proceeds from the notes are as follows (in thousands):



Principal amount	$	345,000
Less initial purchasers’ discount	(8,625		)
Less other issuance costs	(774		)
Net proceeds	$	335,601

Schedule of Debt

The net carrying amount of the liability component of the notes is as follows (in thousands):



	As of June 30, 2018
Principal	$	345,000
Unamortized debt discount	(61,136		)
Unamortized issuance costs	(7,286		)
Net carrying amount	$	276,578

The net carrying amount of the equity component of the notes is as follows (in thousands):



	As of June 30, 2018
Debt discount for conversion option	$	64,193
Issuance costs	(1,749		)
Net carrying amount	$	62,444

Schedule Of Interest Expense Recognized

The following table sets forth the total interest expense recognized related to the notes (in thousands):



	Three Months Ended June 30, 2018
Contractual interest expense	$	210
Amortization of debt discount	3,057
Amortization of issuance costs	364
Total interest expense	$	3,631

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2018

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 June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Cost of revenues	$	103	$	88	$	197	$	155
Research and development	3,529		3,387		7,662		6,628
Sales and marketing	1,730		1,201		3,319		2,327
General and administrative	6,681		4,423		12,507		8,267
Total share-based compensation expense	$	12,043	$	9,099	$	23,685	$	17,377

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, 2017	14,335,115		$	6.78
Granted	3,004,611		20.16
Released	(4,784,787	)	6.34
Canceled	(1,337,685	)	6.27
Balance at June 30, 2018	11,217,254		$	10.62

Restructuring Charges (Tables)

6 Months Ended

Jun. 30, 2018

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, 2017	$	—		$	—		$	—	$	306		$	306
Restructuring charges (credits)	941			148			—		(42		)	1,047
Cash payments	(897		)	(128		)	—		(43		)	(1,068		)
Write-offs	—			(20		)	—		—			(20		)
Balance at December 31, 2017	44			—			—		221			265
Restructuring charges	46			10			—		179			235
Cash payments	(42		)	(10		)	—		(112		)	(164		)
Write-offs	—			—			—		(18		)	(18		)
Balance at June 30, 2018	$	48		$	—		$	—	$	270		$	318

Background and Basis of Presentation (Details) - USD ($)	6 Months Ended
	Jun. 30, 2018	Apr. 30, 2018
Cost-method Investments \| Other Assets
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Investments	$ 3,000,000
Chegg Services
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue recognition, subscription service period	1 year
Minimum \| Required Materials
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue recognition, textbook rental or sale, contractual period	2 months
Maximum \| Required Materials
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue recognition, textbook rental or sale, contractual period	5 months
Senior Notes \| 0.25% Convertible Senior Notes Due 2023
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Face value	$ 345,000,000	$ 345,000,000
Interest rate, stated percentage		0.25%

Revenues (Details) - USD ($)	3 Months Ended		6 Months Ended
Revenues (Details) - USD ($)	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total net revenues	$ 74,222,000	$ 56,317,000	$ 151,171,000	$ 118,919,000
Change in total net revenues	$ 17,905,000		$ 32,252,000
Change in total net revenues, percent	32.00%		27.00%
Deferred revenue, revenue recognized	$ 14,500,000		$ 11,200,000
Contract with customer, liability, revenue recognized	0		0
Aggregate amount of unsatisfied performance obligations	17,700,000		17,700,000
Accounts receivable	8,096,000		8,096,000		$ 10,855,000
Deferred revenue	13,710,000		13,710,000		$ 13,440,000
Change in accounts receivable			(2,759,000)
Change in deferred revenue			$ 270,000
Change in accounts receivable, percent			(25.00%)
Change in deferred revenue, percent			2.00%
Enrollment Marketing
Disaggregation of Revenue [Line Items]
Change in deferred revenue	800,000		$ 1,100,000
Chegg Services
Disaggregation of Revenue [Line Items]
Total net revenues	61,849,000	44,700,000	118,126,000	85,735,000
Change in total net revenues	$ 17,149,000		$ 32,391,000
Change in total net revenues, percent	38.00%		38.00%
Required Materials
Disaggregation of Revenue [Line Items]
Total net revenues	$ 12,373,000	$ 11,617,000	$ 33,045,000	$ 33,184,000
Change in total net revenues	$ 756,000		$ (139,000)
Change in total net revenues, percent	7.00%		0.00%

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

6 Months Ended

Jun. 30, 2018

Jun. 30, 2017

Jun. 30, 2018

Jun. 30, 2017

Numerator:

Net loss

$ (3,909)

$ (6,025)

^[1]

$ (6,526)

$ (12,426)

^[1]

Denominator:

Weighted average shares used to compute net loss per share, basic and diluted (in shares)

112,738

95,047

111,826

93,943

Net loss per share, basic and diluted (in dollars per share)

$ (0.03)

$ (0.06)

$ (0.13)

[1]	Adjusted to reflect the adoption of ASU 2016-18. See Note 1 for more information.

Net Loss Per Share - Shares Excluded From Computation Of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	11,448	3,434	12,449	3,669
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	4,369	3,119	4,321	3,395
RSUs and PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	7,079	107	8,128	66
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	0	8	0	8
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	0	200

Cash and Cash Equivalents, and Investment - Additional Information (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Cost-method Investments [Line Items]
Restricted cash	$ 0.5	$ 0.5
Other Assets \| Equity Investments
Schedule of Cost-method Investments [Line Items]
Investments	$ 3.0

Cash and Cash Equivalents, and Investment - Schedule of Available For Sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Cash and cash equivalents:
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 384,922	$ 126,457
Net Unrealized Gain/(Loss)	4	0
Fair Value	384,926	126,457
Short-term investments:
Schedule of Available-for-sale Securities [Line Items]
Cost	81,052	81,829
Net Unrealized Gain/(Loss)	(114)	(87)
Fair Value	80,938	81,742
Total long-term investments
Schedule of Available-for-sale Securities [Line Items]
Cost	16,011	20,405
Net Unrealized Gain/(Loss)	(54)	(100)
Fair Value	15,957	20,305
Corporate securities \| Short-term investments:
Schedule of Available-for-sale Securities [Line Items]
Cost	35,099	23,001
Net Unrealized Gain/(Loss)	(118)	(43)
Fair Value	34,981	22,958
Corporate securities \| Total long-term investments
Schedule of Available-for-sale Securities [Line Items]
Cost	14,389	20,405
Net Unrealized Gain/(Loss)	(53)	(100)
Fair Value	14,336	20,305
Commercial paper \| Short-term investments:
Schedule of Available-for-sale Securities [Line Items]
Cost	36,493	38,850
Net Unrealized Gain/(Loss)	6	(27)
Fair Value	36,499	38,823
U.S. treasury securities \| Short-term investments:
Schedule of Available-for-sale Securities [Line Items]
Cost	9,460	19,978
Net Unrealized Gain/(Loss)	(2)	(17)
Fair Value	9,458	19,961
U.S. treasury securities \| Total long-term investments
Schedule of Available-for-sale Securities [Line Items]
Cost	1,622	0
Net Unrealized Gain/(Loss)	(1)	0
Fair Value	1,621	0
Cash \| Cash and cash equivalents:
Schedule of Available-for-sale Securities [Line Items]
Cost	350,638	98,370
Net Unrealized Gain/(Loss)	0	0
Fair Value	350,638	98,370
Money market funds \| Cash and cash equivalents:
Schedule of Available-for-sale Securities [Line Items]
Cost	5,032	5,358
Net Unrealized Gain/(Loss)	0	0
Fair Value	5,032	5,358
Commercial paper \| Cash and cash equivalents:
Schedule of Available-for-sale Securities [Line Items]
Cost	29,252	22,729
Net Unrealized Gain/(Loss)	4	0
Fair Value	$ 29,256	$ 22,729

Cash and Cash Equivalents, and Investment - Contractual Maturity (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Cash and Cash Equivalents [Abstract]
Due in 1 year or less, Cost	$ 110,304
Due in 1-2 years, Cost	16,011
Investments not due at a single maturity date, Cost	5,032
Total, Cost	131,347
Due in 1 year or less, Fair Value	110,194
Due in 1-2 years, Fair Value	15,957
Investments not due at a single maturity date, Fair Value	5,032
Total, Fair Value	$ 131,183
Weighted average maturity	5 months

Fair Value Measurement (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 80,938	$ 81,742
Long-term investments	15,957	20,305
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	131,183	130,134
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	16,111	25,319
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	115,072	104,815
Commercial paper \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	36,499	38,823
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]
Short-term investments	0	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]
Short-term investments	36,499	38,823
Corporate securities \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	34,981	22,958
Long-term investments	14,336	20,305
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	0
Long-term investments	0	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	34,981	22,958
Long-term investments	14,336	20,305
U.S. treasury securities \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	9,458	19,961
Long-term investments	1,621
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	9,458	19,961
Long-term investments	1,621
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	0	0
Long-term investments	0
Money market funds \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	5,032	5,358
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	5,032	5,358
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	0
Commercial paper \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	29,256	22,729
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	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	$ 29,256	$ 22,729

Fair Value Measurement - Debt (Details) - Senior Notes - Fair Value, Measurements, Nonrecurring $ in Thousands	Jun. 30, 2018 USD ($)
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes, net	$ 276,578
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes, net	$ 413,569

Acquisition (Details) - WriteLab, Inc. - USD ($) $ in Thousands		3 Months Ended
	May 15, 2018	Jun. 30, 2018
Business Acquisition [Line Items]
Initial cash consideration	$ 12,450
Escrow	2,550
Net working capital adjustment	(483)
Fair value of purchase consideration	14,517
Contingent payments	$ 5,000
Contingent consideration, liability		$ 200
Acquisition related costs		$ 400

Acquisition - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jun. 30, 2018	May 15, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 135,842		$ 125,272	$ 116,239
WriteLab, Inc.
Business Acquisition [Line Items]
Cash		$ 82
Accounts receivable		14
Developed technology		4,450
Total identifiable assets acquired		4,546
Liabilities assumed		(826)
Goodwill		10,797
Total fair value of purchase consideration		$ 14,517

Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Beginning balance	$ 125,272	$ 116,239
Additions due to acquisition	10,797	9,024
Foreign currency translation adjustment	(227)	9
Ending balance	$ 135,842	$ 125,272

Goodwill and Intangible Assets - Finite-lived and Indefinite-lived Intangibe Assets (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	61 months	57 months
Accumulated Amortization	$ (24,564)	$ (21,701)
Net Carrying Amount	18,991
Indefinite-lived trade name	3,600	3,600
Foreign currency translation adjustment	(143)	6
Total intangible assets, gross carrying amount	47,155	42,854
Intangible assets, net	$ 22,591	$ 21,153
Developed technologies
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	74 months	70 months
Gross Carrying Amount	$ 25,107	$ 20,657
Accumulated Amortization	(11,555)	(10,220)
Net Carrying Amount	$ 13,552	$ 10,437
Customer lists
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	47 months	47 months
Gross Carrying Amount	$ 9,970	$ 9,970
Accumulated Amortization	(6,163)	(5,480)
Net Carrying Amount	$ 3,807	$ 4,490
Trade names
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	46 months	46 months
Gross Carrying Amount	$ 5,793	$ 5,793
Accumulated Amortization	(4,214)	(3,465)
Net Carrying Amount	$ 1,579	$ 2,328
Non-compete agreements
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	30 months	30 months
Gross Carrying Amount	$ 1,798	$ 1,798
Accumulated Amortization	(1,602)	(1,506)
Net Carrying Amount	$ 196	$ 292
Master service agreements
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	21 months	21 months
Gross Carrying Amount	$ 1,030	$ 1,030
Accumulated Amortization	(1,030)	(1,030)
Net Carrying Amount	$ 0	$ 0

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Acquisition-Related Intangible Assets
Finite Lived Intangible Assets [Line Items]
Amortization expense of acquisition related to acquired intangible assets	$ 1.4	$ 1.4	$ 2.9	$ 2.8

Goodwill and Intangible Assets - Estimated Future Amortization Expense Related to Intangible Assets (Details) $ in Thousands	Jun. 30, 2018 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remaining six months of 2018	$ 2,795
2019	4,903
2020	3,431
2021	2,074
2022	1,631
Thereafter	4,157
Net Carrying Amount	$ 18,991

Convertible Senior Notes - Convertible Senior Notes (Details)

1 Months Ended

6 Months Ended

Jun. 30, 2018

USD ($)

$ / shares

Apr. 30, 2018

USD ($)

day

$ / shares

shares

Jun. 30, 2018

USD ($)

$ / shares

Jun. 30, 2017

USD ($)

^[1]

Sep. 30, 2018

$ / shares

Debt Instrument [Line Items]

Net proceeds

$ 335,601,000

$ 0

Senior Notes | 0.25% Convertible Senior Notes Due 2023

Debt Instrument [Line Items]

Face value

$ 345,000,000

345,000,000

Interest rate, stated percentage

0.25%

Option to purchase additional notes

$ 45,000,000

Less initial purchasers’ discount

(8,625,000)

Less other issuance costs

(774,000)

Net proceeds

$ 335,601,000

Conversion ratio

0.037051

Equity component

$ 62,444,000

$ 64,200,000

$ 62,444,000

Debt issuance costs

(9,400,000)

Debt instrument, remaining useful life

4 years 10 months 24 days

Share price (in dollars per share) | $ / shares

$ 27.79

Principal

$ 355,700,000

Debt instrument, if-converted value in excess of principal

$ (10,700,000)

Interest rate, effective percentage

4.34%

Sale Price Is Greater Or Equal 130% | Senior Notes | 0.25% Convertible Senior Notes Due 2023

Debt Instrument [Line Items]

Threshold trading days | day

20

Threshold consecutive trading days | day

30

Threshold percentage of stock price trigger

130.00%

Trading Price Per $1,000 Principal Amount Less Than 98% | Senior Notes | 0.25% Convertible Senior Notes Due 2023

Debt Instrument [Line Items]

Threshold trading days | day

5

Threshold consecutive trading days | day

10

Trading Price Per $1,000 Principal Amount Less Than 98% | Senior Notes | 0.25% Convertible Senior Notes Due 2023 | Maximum

Debt Instrument [Line Items]

Threshold percentage of stock price trigger

98.00%

Liability component | Senior Notes | 0.25% Convertible Senior Notes Due 2023

Debt Instrument [Line Items]

Net carrying amount

$ 280,800,000

Debt issuance costs

(7,700,000)

Equity component | Senior Notes | 0.25% Convertible Senior Notes Due 2023

Debt Instrument [Line Items]

Debt issuance costs

(1,700,000)

Capped Call | Senior Notes | 0.25% Convertible Senior Notes Due 2023

Debt Instrument [Line Items]

Net proceeds

$ 39,200,000

Conversion price | $ / shares

$ 26.95

Shares covered by capped call transactions (in shares) | shares

12,801,259.5

Scenario, Forecast | Capped Call | Senior Notes | 0.25% Convertible Senior Notes Due 2023

Debt Instrument [Line Items]

Conversion price | $ / shares

$ 40.68

[1]	Adjusted to reflect the adoption of ASU 2016-18. See Note 1 for more information.

Convertible Senior Notes - Net Carrying Amount (Details) - USD ($)	Jun. 30, 2018	Apr. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Net carrying amount	$ 276,578,000		$ 0
Senior Notes \| 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Principal	345,000,000	$ 345,000,000
Unamortized debt discount	(61,136,000)
Unamortized issuance costs	(7,286,000)
Net carrying amount	276,578,000
Debt discount for conversion option	64,193,000
Issuance costs	(1,749,000)
Net carrying amount	$ 62,444,000	$ 64,200,000

Convertible Senior Notes - Interest Expense Recognized (Details) - Senior Notes - 0.25% Convertible Senior Notes Due 2023 $ in Thousands	3 Months Ended
	Jun. 30, 2018 USD ($)
Debt Instrument [Line Items]
Contractual interest expense	$ 210
Amortization of debt discount	3,057
Amortization of issuance costs	364
Total interest expense	$ 3,631

Revolving Line of Credit (Details) - Revolving Credit Facility - USD ($)	3 Months Ended	6 Months Ended	9 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2019	Sep. 30, 2016
Debt Instrument [Line Items]
Face value						$ 30,000,000.0
Maximum borrowing capacity		$ 30,000,000	$ 30,000,000			$ 50,000,000.0
EBITDA calculation expense threshold, acquisition expenses permissible		6,000,000.0
EBITDA calculation expense threshold, nonrecurring expenses		2,000,000.0
Cash and cash equivalents minimum balance	$ 25,000,000.0	30,000,000.0
EBITDA target			30,000,000.0	$ 25,000,000.0
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					$ 35,000,000.0

Commitments and Contingencies (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Rental expense	$ 0.7	$ 0.7	$ 1.4	$ 1.4

Stockholders' Equity - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 12,043	$ 9,099	$ 23,685	$ 17,377
Cost of revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	103	88	197	155
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	3,529	3,387	7,662	6,628
Sales and marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	1,730	1,201	3,319	2,327
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 6,681	$ 4,423	$ 12,507	$ 8,267

Stockholders' Equity - Additional Information (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized share-based compensation		$ 0	$ 0
RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to restricted stock units	$ 76,500,000	$ 76,500,000
Weighted average vesting period for recognition of compensation expense		1 year 9 months 7 days
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares repurchased (in shares)	983,284
Share price (in dollars per share)	$ 20.34	$ 20.34

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Details) - RSUs and PSUs	6 Months Ended
	Jun. 30, 2018 $ / shares shares
Number of RSUs and PSUs Outstanding
Number of RSUs and PSUs Outstanding, Beginning (shares) \| shares	14,335,115
Number of RSUs and PSUs, Granted (shares) \| shares	3,004,611
Number of RSUs and PSUs, Released (shares) \| shares	(4,784,787)
Number of RSUs and PSUs, Canceled (shares) \| shares	(1,337,685)
Number of RSUs and PSUs Outstanding, Ending (shares) \| shares	11,217,254
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Beginning balance (in dollars per share) \| $ / shares	$ 6.78
Weighted Average Grant Date Fair Value, Granted (in dollars per share) \| $ / shares	20.16
Weighted Average Grant Date Fair Value, Released (in dollars per share) \| $ / shares	6.34
Weighted Average Grant Date Fair Value, Canceled (in dollars per share) \| $ / shares	6.27
Weighted Average Grant Date Fair Value, Ending balance (in dollars per share) \| $ / shares	$ 10.62

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 428	$ 716	$ 969	$ 1,363

Restructuring Charges - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
Restructuring Charges - Narrative (Details) $ in Thousands	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) position	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 15	$ 59	$ 235	$ 959	$ 1,047
Restructuring reserve	318		318		265	$ 306
Restructuring reserve, current	200		200
Restructuring reserve, noncurrent	100		$ 100
2017 Restructuring Plan \| Workforce Reduction Costs
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated \| position			50
Restructuring charges			$ 46		941
Restructuring reserve	48		48		44	0
2017 Restructuring Plan \| Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			10		148
Restructuring reserve	0		0		0	0
2015 Restructuring Plan \| Workforce Reduction Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			0		0
Restructuring reserve	0		0		0	0
2015 Restructuring Plan \| Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			179		(42)
Restructuring reserve	$ 270		$ 270		$ 221	$ 306

Restructuring Charges - Restructuring Reserve (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Beginning balance			$ 265	$ 306	$ 306
Restructuring charges	$ 15	$ 59	235	959	1,047
Cash payments			(164)		(1,068)
Write-offs			(18)		(20)
Ending balance	318		318		265
2017 Restructuring Plan \| Workforce Reduction Costs
Restructuring Reserve [Roll Forward]
Beginning balance			44	0	0
Restructuring charges			46		941
Cash payments			(42)		(897)
Write-offs			0		0
Ending balance	48		48		44
2017 Restructuring Plan \| Lease Termination and Other Costs
Restructuring Reserve [Roll Forward]
Beginning balance			0	0	0
Restructuring charges			10		148
Cash payments			(10)		(128)
Write-offs			0		(20)
Ending balance	0		0		0
2015 Restructuring Plan \| Workforce Reduction Costs
Restructuring Reserve [Roll Forward]
Beginning balance			0	0	0
Restructuring charges			0		0
Cash payments			0		0
Write-offs			0		0
Ending balance	0		0		0
2015 Restructuring Plan \| Lease Termination and Other Costs
Restructuring Reserve [Roll Forward]
Beginning balance			221	$ 306	306
Restructuring charges			179		(42)
Cash payments			(112)		(43)
Write-offs			(18)		0
Ending balance	$ 270		$ 270		$ 221

Related-Party Transactions (Details)	3 Months Ended		6 Months Ended
Related-Party Transactions (Details)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) board_member	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Adobe Systems \| Chief Executive Officer
Related Party Transaction [Line Items]
Purchases from related party	$ 600,000	$ 1,300,000	$ 2,300,000	$ 1,800,000
Revenue from related parties	0	0	100,000	0
Due to related parties	300,000		300,000		$ 300,000
Receivables from related party	0		0		0
Cengage \| Chief Executive Officer
Related Party Transaction [Line Items]
Revenue from related parties	100,000	200,000	2,000,000	600,000
Due to related parties	900,000		900,000		100,000
Receivables from related party					$ 300,000
Cengage \| Board Of Directors Member
Related Party Transaction [Line Items]
Purchases from related party	1,400,000	1,300,000	$ 6,500,000	4,800,000
Number of board members appointed to Board of Directors of related party \| board_member			1
Receivables from related party	0		$ 0
PayPal \| Board Of Directors Member
Related Party Transaction [Line Items]
Number of board members appointed to Board of Directors of related party \| board_member			1
Expenses from transactions with related party	$ 200,000	$ 200,000	$ 600,000	$ 500,000

Subsequent Event (Details) $ in Millions	Jul. 02, 2018 USD ($)
StudyBlue, Inc. \| Subsequent Event
Subsequent Event [Line Items]
Purchase price	$ 20.8