Chegg (CHGG) 10-Q 26 Oct 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 23, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-36180
Entity Registrant Name	CHEGG, INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-3237489
Entity Address, Address Line One	3990 Freedom Circle
Entity Address, City or Town	Santa Clara
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	95054
City Area Code	408
Local Phone Number	855-5700
Title of 12(b) Security	Common stock, $0.001 par value per share
Trading Symbol	CHGG
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		128,810,888
Entity Central Index Key	0001364954
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 527,541	$ 387,520
Short-term investments	723,327	381,074
Accounts receivable, net of allowance of $198 and $56 at September 30, 2020 and December 31, 2019, respectively	12,487	11,529
Prepaid expenses	15,082	10,538
Other current assets	21,059	16,606
Total current assets	1,299,496	807,267
Long-term investments	521,261	310,483
Textbook library, net	34,575	0
Property and equipment, net	113,058	87,359
Goodwill	284,809	214,513
Intangible assets, net	55,386	34,667
Right of use assets	14,124	15,931
Other assets	18,948	18,778
Total assets	2,341,657	1,488,998
Current liabilities
Accounts payable	5,838	7,362
Deferred revenue	51,941	18,780
Current operating lease liabilities	5,652	5,283
Accrued liabilities	79,524	39,964
Total current liabilities	142,955	71,389
Long-term liabilities
Convertible senior notes, net	1,536,984	900,303
Long-term operating lease liabilities	11,661	14,513
Other long-term liabilities	4,665	3,964
Total long-term liabilities	1,553,310	918,780
Total liabilities	1,696,265	990,169
Commitments and contingencies
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; 128,654,401 and 121,583,501 shares issued and outstanding at September 30, 2020 and December 31, 2019, respectively	129	122
Additional paid-in capital	1,092,574	916,095
Accumulated other comprehensive income (loss)	1,333	(1,096)
Accumulated deficit	(448,644)	(416,292)
Total stockholders' equity	645,392	498,829
Total liabilities and stockholders' equity	$ 2,341,657	$ 1,488,998

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 198	$ 56
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	128,654,401	121,583,501
Common stock, shares outstanding (in shares)	128,654,401	121,583,501

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net revenues	$ 154,018	$ 94,151	$ 438,617	$ 285,422
Cost of revenues	62,370	22,164	148,284	66,017
Gross profit	91,648	71,987	290,333	219,405
Operating expenses:
Research and development	44,041	36,442	123,956	101,199
Sales and marketing	24,625	16,822	60,621	47,334
General and administrative	40,784	23,752	98,221	70,044
Restructuring charges	0	28	0	97
Total operating expenses	109,450	77,044	282,798	218,674
(Loss) income from operations	(17,802)	(5,057)	7,535	731
Interest expense, net and other (expense) income, net:
Interest expense, net	(17,468)	(13,548)	(44,320)	(31,294)
Other (expense) income, net	(804)	7,751	7,396	14,571
Total interest expense, net and other (expense) income, net	(18,272)	(5,797)	(36,924)	(16,723)
Loss before provision for income taxes	(36,074)	(10,854)	(29,389)	(15,992)
Provision for income taxes	1,066	623	2,875	1,832
Net loss	$ (37,140)	$ (11,477)	$ (32,264)	$ (17,824)
Net loss per share, basic and diluted (in dollars per share)	$ (0.29)	$ (0.10)	$ (0.26)	$ (0.15)
Weighted average shares used to compute net loss per share, basic and diluted (in shares)	126,194	120,085	124,162	118,547

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (37,140)	$ (11,477)	$ (32,264)	$ (17,824)
Other comprehensive (loss) income
Change in net unrealized (loss) gain on available for sale investments, net of tax	(1,642)	(73)	1,922	379
Change in foreign currency translation adjustments, net of tax	1,125	(1,067)	507	(1,118)
Other comprehensive (loss) income	(517)	(1,140)	2,429	(739)
Total comprehensive loss	$ (37,657)	$ (12,617)	$ (29,835)	$ (18,563)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated DeficitCumulative Effect, Period of Adoption, Adjustment
Common stock, beginning balance (in shares) at Dec. 31, 2018			115,500,000
Beginning balance at Dec. 31, 2018	$ 410,634	$ (111)	$ 116	$ 818,113	$ (1,019)	$ (406,576)	$ (111)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Equity component of convertible senior notes, net of issuance costs	$ 206,747			206,747
Purchase of convertible senior notes capped call	(97,200)			(97,200)
Repurchase of common stock (in shares)			(504,000)
Repurchase of common stock	(20,000)		$ (1)	(19,999)
Issuance of common stock upon exercise of stock options and ESPP (in shares)			2,545,000
Issuance of common stock upon exercise of stock options and ESPP	27,720		$ 3	27,717
Net issuance of common stock for settlement of RSUs (in shares)			3,064,000
Net issuance of common stock for settlement of equity awards	(91,073)		$ 3	(91,076)
Issuance of common stock in connection with prior acquisition (in shares)			64,000
Issuance of common stock in connection with prior acquisition	3,003			3,003
Share-based compensation expense	47,355			47,355
Other comprehensive income (loss)	(739)				(739)
Net loss	(17,824)					(17,824)
Common stock, ending balance (in shares) at Sep. 30, 2019			120,669,000
Beginning balance at Sep. 30, 2019	468,512		$ 121	894,660	(1,758)	(424,511)
Common stock, beginning balance (in shares) at Jun. 30, 2019			119,336,000
Beginning balance at Jun. 30, 2019	459,571		$ 119	873,104	(618)	(413,034)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and ESPP (in shares)			991,000
Issuance of common stock upon exercise of stock options and ESPP	11,674		$ 1	11,673
Net issuance of common stock for settlement of RSUs (in shares)			319,000
Net issuance of common stock for settlement of equity awards	(8,824)		$ 1	(8,825)
Issuance of common stock in connection with prior acquisition (in shares)			23,000
Issuance of common stock in connection with prior acquisition	1,843			1,843
Share-based compensation expense	16,865			16,865
Other comprehensive income (loss)	(1,140)				(1,140)
Net loss	(11,477)					(11,477)
Common stock, ending balance (in shares) at Sep. 30, 2019			120,669,000
Beginning balance at Sep. 30, 2019	$ 468,512		$ 121	894,660	(1,758)	(424,511)
Common stock, beginning balance (in shares) at Dec. 31, 2019	121,583,501		121,584,000
Beginning balance at Dec. 31, 2019	$ 498,829	$ (88)	$ 122	916,095	(1,096)	(416,292)	$ (88)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Equity component of convertible senior notes, net of issuance costs	$ 237,462			237,462
Purchase of convertible senior notes capped call	(103,400)			(103,400)
Equity component related to conversions of 2023 convertible senior notes	(345,552)			(345,552)
Issuance of common stock upon conversion of 2023 convertible senior notes (in shares)			4,182,000
Issuance of common stock upon conversion of 2023 convertible senior notes	327,141		$ 4	327,137
Proceeds from capped call related to conversions of 2023 convertible senior notes	57,414			57,414
Issuance of common stock upon exercise of stock options and ESPP (in shares)			778,000
Issuance of common stock upon exercise of stock options and ESPP	9,234		$ 1	9,233
Net issuance of common stock for settlement of RSUs (in shares)			2,110,000
Net issuance of common stock for settlement of equity awards	(65,222)		$ 2	(65,224)
Share-based compensation expense	59,409			59,409
Other comprehensive income (loss)	2,429				2,429
Net loss	$ (32,264)					(32,264)
Common stock, ending balance (in shares) at Sep. 30, 2020	128,654,401		128,654,000
Beginning balance at Sep. 30, 2020	$ 645,392		$ 129	1,092,574	1,333	(448,644)
Common stock, beginning balance (in shares) at Jun. 30, 2020			124,123,000
Beginning balance at Jun. 30, 2020	498,378		$ 124	907,908	1,850	(411,504)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity component of convertible senior notes, net of issuance costs	237,462			237,462
Purchase of convertible senior notes capped call	(103,400)			(103,400)
Equity component related to conversions of 2023 convertible senior notes	(345,552)			(345,552)
Issuance of common stock upon conversion of 2023 convertible senior notes (in shares)			4,182,000
Issuance of common stock upon conversion of 2023 convertible senior notes	327,141		$ 4	327,137
Proceeds from capped call related to conversions of 2023 convertible senior notes	57,414			57,414
Issuance of common stock upon exercise of stock options and ESPP (in shares)			106,000
Issuance of common stock upon exercise of stock options and ESPP	1,197		$ 1	1,196
Net issuance of common stock for settlement of RSUs (in shares)			243,000
Net issuance of common stock for settlement of equity awards	(11,120)		$ 0	(11,120)
Share-based compensation expense	21,529			21,529
Other comprehensive income (loss)	(517)				(517)
Net loss	$ (37,140)					(37,140)
Common stock, ending balance (in shares) at Sep. 30, 2020	128,654,401		128,654,000
Beginning balance at Sep. 30, 2020	$ 645,392		$ 129	$ 1,092,574	$ 1,333	$ (448,644)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net loss	$ (32,264)	$ (17,824)
Adjustments to reconcile net loss to net cash provided by operating activities:
Print textbook depreciation expense	10,699	0
Other depreciation and amortization expense	33,088	21,369
Share-based compensation expense	59,409	47,355
Amortization of debt discount and issuance costs	42,910	30,114
Repayment of convertible senior notes attributable to debt discount	(14,912)	0
Loss on early extinguishment of debt	3,315	0
Loss from write-off of property and equipment	1,057	832
Loss from impairment of strategic equity investment	10,000	0
Gain on textbook library, net	(2,028)	0
Deferred income taxes	(17)	59
Operating lease expense, net of accretion	3,400	3,284
Other non-cash items	(85)	(370)
Change in assets and liabilities, net of effect of acquisition of business:
Accounts receivable	106	(850)
Prepaid expenses and other current assets	(6,178)	(20,741)
Other assets	(2,638)	1,989
Accounts payable	(1,634)	(3,983)
Deferred revenue	32,239	10,039
Accrued liabilities	34,276	18,095
Other liabilities	(2,088)	(2,793)
Net cash provided by operating activities	168,655	86,575
Cash flows from investing activities
Purchases of property and equipment	(57,457)	(31,520)
Purchases of textbooks	(49,641)	0
Proceeds from disposition of textbooks	7,012	0
Purchases of investments	(968,106)	(822,869)
Proceeds from sale of investments	0	53,261
Maturities of investments	412,046	190,744
Purchase of strategic equity investment	(2,000)	0
Acquisition of business, net of cash acquired	(92,796)	0
Net cash used in investing activities	(750,942)	(610,384)
Cash flows from financing activities
Proceeds from common stock issued under stock plans, net	9,236	27,723
Payment of taxes related to the net share settlement of equity awards	(65,224)	(91,076)
Proceeds from issuance of convertible senior notes, net of issuance costs	984,096	780,180
Purchase of convertible senior notes capped call	(103,400)	(97,200)
Repayment of convertible senior notes	(159,677)	0
Proceeds from exercise of convertible senior notes capped call	57,414	0
Repurchase of common stock	0	(20,000)
Net cash provided by financing activities	722,445	599,627
Net increase in cash, cash equivalents and restricted cash	140,158	75,818
Cash, cash equivalents and restricted cash, beginning of period	389,432	375,945
Cash, cash equivalents and restricted cash, end of period	529,590	451,763
Supplemental cash flow data:
Interest	1,546	901
Income taxes	2,450	1,492
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	5,174	3,847
Right of use assets obtained in exchange for operating lease obligations	1,713	2,638
Non-cash investing and financing activities:
Accrued purchases of long-lived assets	6,102	4,452
Accrued escrow related to acquisition	7,451	0
Issuance of common stock related to prior acquisition	0	3,003
Issuance of common stock related to repayment of convertible senior notes	327,141	0
Reconciliation of cash, cash equivalents and restricted cash:
Total cash, cash equivalents and restricted cash	$ 529,590	$ 451,763

Background and Basis of Present

Background and Basis of Presentation	9 Months Ended
	Sep. 30, 2020
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 a 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 September 30, 2020, the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss, and the condensed consolidated statements of stockholder's equity for the three and nine months ended September 30, 2020 and 2019, and the condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019, and the related footnote disclosures are unaudited. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, including normal recurring adjustments, necessary to present fairly our financial position as of September 30, 2020, our results of operations, results of comprehensive loss, and stockholder's equity for the three and nine months ended September 30, 2020 and 2019, and cash flows for the nine months ended September 30, 2020 and 2019. Our results of operations, results of comprehensive loss, stockholder's equity, and cash flows for the nine months ended September 30, 2020 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, 2019 as 2019. 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, 2019 (the Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). Except for our policies on investments, textbook library, convertible senior notes, net, revenue recognition and deferred revenue, and cost of revenues, 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. Investments We hold investments in commercial paper, corporate debt securities, U.S. treasury securities, and agency bonds. We classify our investments as available-for-sale based on the nature of each security that are either short or long-term based on the remaining contractual maturity of the investment. Our available-for-sale investments are carried at estimated fair value with any unrealized gains and losses unrelated to credit loss factors, net of taxes, included in other comprehensive (loss) income in our condensed consolidated statements of stockholders’ equity. Beginning in 2020, unrealized losses related to credit loss factors are now recorded through an allowance for credit losses in other (expense) income, net in our condensed consolidated statements of operations, rather than as a reduction to the amortized cost basis in other comprehensive (loss) income, when a decline in fair value has resulted from a credit loss. We determine realized gains or losses on the sale of investments on a specific identification method, and record such gains or losses as other (expense) income, net in our condensed consolidated statements of operations. Textbook Library Beginning in January 2020, we began our transition back to print textbook ownership by purchasing print textbooks to establish our textbook library. We consider our print textbook library to be a long-term productive asset and, as such, classify it as a non-current asset in our condensed consolidated balance sheets. All print textbooks in our textbook library are stated at cost, which includes the purchase price less accumulated depreciation. We write down textbooks on a book-by-book basis for lost, damaged, or excess print textbooks. We depreciate our print textbooks, less an estimated salvage value, over an estimated useful life of four years using an accelerated method of depreciation, as we estimate this method most accurately reflects the actual pattern of decline in their economic value. The salvage value considers the historical trend and projected proceeds for print textbooks. The useful life is determined based on the estimated time period in which the print textbooks are held and rented. We review the estimated salvage value and useful life of our print textbook library on an ongoing basis. Write-downs for print textbooks, print textbook depreciation expense, the gain or loss on print textbooks liquidated, and the net book value of print textbooks purchased by students at the end of the term or on a just-in-time basis are recorded in cost of revenues in our condensed consolidated statements of operations and classified as adjustments to cash flows from operating activities. Cash outflows for the acquisition of print textbooks net of changes in related accounts payable and accrued liabilities, and cash inflows received from the proceeds from the disposition of print textbooks net of changes in related accounts receivable, are classified as cash flows from investing activities in our condensed consolidated statements of cash flows. As of September 30, 2020, our net print textbook library of $34.6 million consisted of gross print textbook library of approximately $44.8 million net of accumulated depreciation and write-downs of approximately $9.2 million and $1.0 million, respectively. During the three and nine months ended September 30, 2020, print textbook depreciation expense was approximately $3.6 million and $10.7 million, respectively, and our net gain on textbook library was approximately $0.6 million and $2.0 million, respectively. Convertible Senior Notes, net In August 2020, we issued $1.0 billion in aggregate principal amount of 0% convertible senior notes due in 2026 (2026 notes). In March 2019, we issued $700 million in aggregate principal amount of 0.125% convertible senior notes due in 2025 (2025 notes) and in April 2019, the initial purchasers fully exercised their option to purchase $100 million of additional 2025 notes for aggregate total gross proceeds of $800 million. In April 2018, we issued $345 million in aggregate principal amount of 0.25% convertible senior notes due in 2023 (2023 notes). Collectively, the 2026 notes, 2025 notes, and the 2023 notes are referred to as the “notes.” In accounting for their issuance, we separated the notes into liability and equity components, as the notes represent convertible instruments with a cash conversion feature. 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 consolidated balance sheet, and is amortized to interest expense over the term of the notes using the effective interest rate method. The carrying amount of the liability component is classified as a long-term liability as we have the election to settle conversion requests in shares of our common stock. The carrying amount of 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. In accounting for extinguishment of the notes, we allocated the consideration transferred between the liability and equity components in a similar manner as upon issuance. The liability component for extinguished notes is then compared to the carrying amount of the respective extinguished notes and a gain or loss is recorded in other (expense) income, net in our condensed consolidated statements of operations. Revenue Recognition and Deferred Revenue We recognize revenues when the control of 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. 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. 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 which primarily includes Chegg Study, Chegg Writing, Chegg Tutors, Chegg Math Solver, Thinkful, and Mathway. Revenues from Chegg Study, Chegg Writing, Chegg Tutors, Chegg Math Solver, and Mathway are primarily recognized ratably over the respective weekly or monthly subscription period. Revenues from Thinkful, our skills-based learning platform, are recognized either ratably over the term of the course, generally six months, or upon completion of the lessons, depending on the instruction type of the course. Revenues from our Required Materials product line includes revenues from print textbooks that we own or that are owned by a partner as well as revenues from eTextbooks. Beginning in 2020, our Required Materials product line includes operating leases with students for the rental of print textbooks that we own. Operating lease income is recognized as the total transaction amount, paid upon commencement of the lease, ratably over the lease term which is generally a two two Some of our customer arrangements 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 multiple performance obligations, we allocate the transaction price based on the relative standalone selling price (SSP) method by comparing the 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. Some of our customer arrangements may include 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. 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. 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. In relation to print textbooks owned by a partner, we recognize revenues on a net basis based on our role in the transaction as an agent as we have concluded that we do not control the use of the print textbooks, and therefore record only the net revenue share we earn. We have concluded that we control our Chegg Services, print textbooks that we own for rental, purchase at the end of the rental term, or sale on a just-in-time basis, and eTextbook service and therefore we recognize revenues and cost of revenues on a gross basis. Contract assets are contained within other current assets and other 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 rental and subscription performance obligations that have not been satisfied and estimated variable consideration. Deferred revenue related to rental and subscription performance obligations 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. Deferred revenue related to variable consideration is recognized as revenues during each reporting period based on the estimated amount we believe we will earn over the life of the contract. We have elected a practical expedient to record incremental costs to obtain or fulfill a contract when the amortization period would have been one year or less as incurred. These incremental costs primarily relate to sales commissions costs and are recorded in sales and marketing expense in our condensed consolidated statements of operations. Cost of Revenues Our cost of revenues consists primarily of expenses associated with the delivery and distribution of our products and services. Cost of revenues primarily consists of publisher content fees for eTextbooks, content amortization expense related to content that we develop, licenses from publishers for which we pay one-time license fees, or acquire through acquisitions, write-downs for print textbooks, the gain or loss on print textbooks liquidated, the net book value of print textbooks purchased by students at the end of the term or on a just-in-time basis, print textbook depreciation expense, payment processing costs, the payments made to tutors through our Chegg Tutors service, personnel costs and other direct costs related to providing products or services. In addition, cost of revenues includes allocated information technology and facilities costs. Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States requires management to make estimates, judgments, and assumptions that affect the reported amounts of assets and liabilities; the disclosure of contingent liabilities at the date of the financial statements; and the reported amounts of revenues and expenses during the reporting periods. Significant estimates, assumptions, and judgments are used for, but not limited to: revenue recognition, recoverability of accounts receivable, share-based compensation expense including estimated forfeitures, accounting for income taxes, textbook library, useful lives assigned to long-lived assets for depreciation and amortization, impairment of goodwill and long-lived assets, the valuation of acquired intangible assets, the valuation of our convertible senior notes, internal-use software and website development costs, operating lease right of use (ROU) assets, and operating lease liabilities. 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 August 2020, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2020-06, Accounting for Convertible Instruments and Contracts in an Entity's Own Equity . ASU 2020-06 simplifies the guidance in Accounting Standards Codification (ASC) 470-20, Debt - Debt with Conversion and Other Options, by reducing the number of accounting separation models for convertible instruments, amends the guidance in ASC 815-40, Derivatives and Hedging - Contracts in Entity's Own Equity, for certain contracts in an entity's own equity that are currently accounted for as derivatives, and requires entities to use the if-converted method for all convertible instruments in the diluted earnings per share (EPS) calculation. Early adoption is permitted, but no earlier than annual periods beginning after December 15, 2020, and the guidance allows for a modified retrospective or fully retrospective method of transition. We currently plan to adopt the guidance on January 1, 2021. At this time, we are continuing to refine the quantitative impact of early adopting this guidance and we initially believe the most significant impacts will be an increase in liabilities on our condensed consolidated balance sheets as a result of removing the accounting separation model for convertible instruments with a cash conversion feature, a significant reduction of non-cash interest expense on our condensed consolidated statements of operations, and an increase in the number of shares included in our diluted EPS calculations. We will continue to evaluate the impacts of this guidance, including method of transition, as we near our adoption date. In March 2020, the FASB issued ASU 2020-04, Facilitation of the Effects of Reference Rate Reform on Financial Reporting . ASU 2020-04 provides temporary optional expedients and exceptions for applying reference rate reform to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The guidance can be applied immediately and only applies to contract modifications made or hedging relationships entered into or evaluated before December 31, 2022. While we do not have any hedging relationships and currently do not believe we have material contracts impacted by reference rate reform, we are in the process of evaluating the impact of this guidance. Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. ASU 2019-12 key changes include hybrid tax regimes, intraperiod tax allocation exception, and interim-period accounting for enacted changes in tax law. We early adopted ASU 2019-12 during the second quarter of 2020 under the prospective method of adoption. As a result of adoption, there was no modification required to the first quarter of 2020 results of operations as previously presented. The FASB issued four ASUs related to ASC 326, Financial Instruments - Credit Losses . In November 2019, the FASB issued ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments - Credit Losses. In May 2019, the FASB issued ASU 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief. In April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . On January 1, 2020, we adopted ASC 326, which replaces the existing incurred loss impairment model for financial assets, including trade receivables, with an expected loss model which requires the use of forward-looking information to calculate expected credit loss estimates. Additionally, the concept of other-than-temporary impairment for available-for-sale investments is eliminated and instead requires us to focus on determining whether any unrealized loss is a result of a credit loss or other factors. We adopted ASC 326 under the modified retrospective method for all financial assets measured at amortized cost. Results for reporting periods beginning after adoption are presented under ASC 326 while we have not changed previously disclosed amounts or provided additional disclosures for comparative periods. We recorded an immaterial cumulative-effect adjustment to trade receivables to the opening balance of accumulated deficit in our condensed consolidated balance sheet. We adopted ASC 326 under the prospective transition approach for available-for-sale investments which resulted in no change to amortized cost basis before and after adoption. Credit losses related to available-for-sale investments will now be recorded through an allowance for credit losses with immediate recognition to our condensed consolidated statement of operations rather than as a reduction to the amortized cost basis and recognition to our condensed consolidated statements of comprehensive loss. See above within Note 1, “Background and Basis of Presentation”, for updates to our significant accounting policies impacted by our adoption of ASC 326 as well as Note 4, “Cash and Cash Equivalents, and Investments” for more information. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with existing guidance contained within subtopic 350-40 to develop or obtain internal-use software. We adopted ASU 2018-15 on January 1, 2020 under the prospective method of adoption.

Revenues

Revenues	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenues	Revenues 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 our print textbook partners, being recognized at the point in time when print textbooks are shipped to students. The following tables set 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 September 30, Change 2020 2019 $ % Chegg Services $ 118,895 $ 69,304 $ 49,591 72 % Required Materials 35,123 24,847 10,276 41 Total net revenues $ 154,018 $ 94,151 $ 59,867 64 Nine Months Ended September 30, Change 2020 2019 $ % Chegg Services $ 345,258 $ 224,903 $ 120,355 54 % Required Materials 93,359 60,519 32,840 54 Total net revenues $ 438,617 $ 285,422 $ 153,195 54 During the three and nine months ended September 30, 2020, we recognized $25.4 million and $18.0 million, respectively, of revenues that were included in our deferred revenue balance at the beginning of each reporting period. During the three and nine months ended September 30, 2019, we recognized $15.7 million and $16.0 million, respectively, of revenues that were included in our deferred revenue balance at the beginning of each reporting period. During the three and nine months ended September 30, 2020, we recognized an immaterial amount of previously deferred revenues recognized from performance obligations satisfied in previous periods. During the three and nine months ended September 30, 2019, we recognized $2.2 million and $2.7 million, respectively, of previously deferred revenues recognized from performance obligations satisfied in previous periods related to variable consideration recognized from our agreement with our Required Materials print textbook partner. During the three and nine months ended September 30, 2020, we recognized $12.0 million and $35.4 million, respectively, of operating lease income from print textbook rentals that we own. The aggregate amount of unsatisfied performance obligations is approximately $51.9 million as of September 30, 2020, which are expected to be recognized as revenues over the next year. Contract Balances The following table presents our accounts receivable, net, deferred revenue, and contract assets balances (in thousands, except percentages): Change September 30, 2020 December 31, 2019 $ % Accounts receivable, net $ 12,487 $ 11,529 $ 958 8 % Deferred revenue 51,941 18,780 33,161 177 Contract assets 8,214 3,531 4,683 133 During the nine months ended September 30, 2020, our accounts receivable, net balance increased by $1.0 million, or 8%, primarily due to timing of billings and seasonality of our business. During the nine months ended September 30, 2020, our deferred revenue balance increased by $33.2 million, or 177%, primarily due to increased bookings driven by the seasonality of our business as well as from print textbooks that we own that are recognized ratably rather than immediately. During the nine months ended September 30, 2020, our contract assets balance increased by $4.7 million, or 133%, primarily due to deferred payment arrangements for Thinkful.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per ShareBasic 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, restricted stock units (RSUs), performance-based restricted stock units (PSUs), and shares related to convertible senior notes, 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 basic and diluted net loss per share (in thousands, except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator: Net loss $ (37,140) $ (11,477) $ (32,264) $ (17,824) Denominator: Weighted average shares used to compute net loss per share, basic and diluted 126,194 120,085 124,162 118,547 Net loss per share, basic and diluted $ (0.29) $ (0.10) $ (0.26) $ (0.15) 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 September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Options to purchase common stock 865 2,122 977 2,715 RSUs and PSUs 3,394 3,831 3,425 4,952 Shares related to convertible senior notes 8,721 4,098 4,422 3,709 Employee stock purchase plan 9 7 4 3 Total common stock equivalents 12,989 10,058 8,828 11,379 Shares related to convertible senior notes during the three and nine months ended September 30, 2020 represents the dilutive and anti-dilutive impact of our 2023 notes and 2025 notes as the average price of our common stock was higher than the conversion price of $26.95 and $51.56, respectively, and the conditions for conversion had been met. Shares related to convertible senior notes during the three and nine months ended September 30, 2019 represents the dilutive and anti-dilutive impact of our 2023 notes as the average price of our common stock was higher than the conversion price and the conditions for conversion had been met. While these shares are anti-dilutive during the three and nine months ended September 30, 2020 and 2019, they may be dilutive in periods we report net income. However, as a result of the capped call transactions, there will be no economic dilution from the 2023 notes and 2025 notes up to $40.68 and $79.32, respectively, as exercise of the capped call instruments will reduce dilution that would have otherwise occurred when the average price of our common stock exceeds the conversion price. None of the shares related to our 2025 notes were dilutive or anti-dilutive during the three and nine months ended September 30, 2019 as a result of the conditions for conversion not being met. None of the shares related to our 2026 notes were dilutive or anti-dilutive during the three and nine months ended September 30, 2020 as a result of the conditions for conversion not being met. For further information on the notes see Note 8, “Convertible Senior Notes.”

Cash and Cash Equivalents, and

Cash and Cash Equivalents, and Investments	9 Months Ended
	Sep. 30, 2020
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents, and Investment	Cash and Cash Equivalents, and Investments The following tables show our cash and cash equivalents, and investments’ adjusted cost, unrealized gain, unrealized loss, and fair value as of September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 17,346 $ — $ — $ 17,346 U.S. treasury securities 307,673 — — 307,673 Money market funds 202,522 — — 202,522 Total cash and cash equivalents $ 527,541 $ — $ — $ 527,541 Short-term investments: Commercial paper $ 204,044 $ 38 $ (24) $ 204,058 Corporate securities 516,682 2,644 (57) 519,269 Total short-term investments $ 720,726 $ 2,682 $ (81) $ 723,327 Long-term investments: Corporate securities $ 456,774 $ 602 $ (635) $ 456,741 Agency bonds 64,495 25 — 64,520 Total long-term investments $ 521,269 $ 627 $ (635) $ 521,261 December 31, 2019 Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 241,355 $ — $ — $ 241,355 Money market funds 146,165 — — 146,165 Total cash and cash equivalents $ 387,520 $ — $ — $ 387,520 Short-term investments: Commercial paper $ 7,489 $ — $ — $ 7,489 Corporate securities 318,946 425 (78) 319,293 U.S. treasury securities 44,251 39 (4) 44,286 Agency bonds 10,000 6 — 10,006 Total short-term investments $ 380,686 $ 470 $ (82) $ 381,074 Long-term investments: Corporate securities $ 295,103 $ 533 $ (158) $ 295,478 Agency bonds 14,999 6 — 15,005 Total long-term investments $ 310,102 $ 539 $ (158) $ 310,483 The following table shows our cash equivalents and investments' adjusted cost and fair value by contractual maturity as of September 30, 2020 (in thousands): Adjusted Cost Fair Value Due in 1 year or less $ 1,028,399 $ 1,031,000 Due in 1-2 years 521,269 521,261 Investments not due at a single maturity date 202,522 202,522 Total $ 1,752,190 $ 1,754,783 Investments not due at a single maturity date in the preceding table consisted of money market funds. As of September 30, 2020, we did not consider the declines in market value of our investment portfolio to be driven by credit related factors. When evaluating whether an investment's unrealized losses are related to credit factors, we review factors such as the extent to which fair value is below its cost basis, any changes to the credit rating of the security, adverse conditions specifically related to the security, changes in market interest rates and our intent to sell, or whether it is more likely than not we will be required to sell, before recovery of cost basis. We invest in highly-rated securities with a minimum credit rating of A-, a weighted average maturity of less than 12 months, and our investment policy limits the amount of credit exposure to any one issuer or industry sector. 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. During the three and nine months ended September 30, 2020, we did not recognize any losses on our investments due to credit related factors. During the three and nine months ended September 30, 2019, we did not recognize any impairment charges. Restricted Cash As of September 30, 2020 and December 31, 2019, we had approximately $2.0 million and $1.9 million, respectively, of restricted cash that primarily consists of security deposits for our corporate offices. These amounts are classified in either other current assets or other assets on our condensed consolidated balance sheets based upon the term of the remaining restrictions. Strategic Investments In March 2020, we completed an investment of $2.0 million in TAPD, Inc., also known as Frank, a U.S.-based service that helps students access financial aid. In October 2018, we completed an investment of $10.0 million in WayUp, Inc. (WayUp), a U.S.-based job site and mobile application for college students and recent graduates. Additionally, we previously invested $3.0 million in a foreign entity to explore expanding our reach internationally. During the three months ended September 30, 2020, we recorded a $10.0 million impairment charge on our investment in WayUp included within general and administrative expense on our condensed consolidated statements of operations. Our impairment assessment was the result of the uncertainty around WayUp's ability to raise additional funding to support their future operations. We did not record any impairment charges on our other strategic investments during the three and nine months ended September 30, 2020 and 2019, as there were no other significant identified events or changes in circumstances that would be considered an indicator for impairment. We considered general market conditions as a result of the COVID-19 pandemic in our impairment analysis. There were no observable price changes in orderly transactions for the identical or similar investments of the same issuers during the three and nine months ended September 30, 2020 and 2019.

Fair Value Measurement

Fair Value Measurement	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement We have established a fair value hierarchy used to determine the fair value of our financial instruments as follows: Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities. Level 2—Inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments. Level 3—Inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value; the inputs require significant management judgment or estimation. A financial instrument’s classification within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Financial instruments measured and recorded at fair value on a recurring basis as of September 30, 2020 and December 31, 2019 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2020 Total Level 1 Level 2 Assets: Cash equivalents: U.S. treasury securities $ 307,673 $ 307,673 $ — Money market funds 202,522 202,522 — Short-term investments: Commercial paper 204,058 — 204,058 Corporate securities 519,269 — 519,269 Long-term investments: Corporate securities 456,741 — 456,741 Agency bonds 64,520 — 64,520 Total assets measured and recorded at fair value $ 1,754,783 $ 510,195 $ 1,244,588 December 31, 2019 Total Level 1 Level 2 Assets: Cash equivalents: Money market funds $ 146,165 $ 146,165 $ — Short-term investments: Commercial paper 7,489 — 7,489 Corporate securities 319,293 — 319,293 U.S. treasury securities 44,286 44,286 — Agency bonds 10,006 — 10,006 Long-term investments: Corporate securities 295,478 — 295,478 Agency bonds 15,005 — 15,005 Total assets measured and recorded at fair value $ 837,722 $ 190,451 $ 647,271 We value our investments 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 investments 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 investments 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 estimated fair value of the notes was determined based on the 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, “Convertible Senior Notes.” The carrying amounts and estimated fair values of the notes as of September 30, 2020 and December 31, 2019 are as follows (in thousands): September 30, 2020 December 31, 2019 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value 2026 notes $ 751,349 $ 1,000,000 $ — $ — 2025 notes 631,061 1,208,800 602,611 831,000 2023 notes 154,574 462,358 297,692 523,538 Convertible senior notes, net $ 1,536,984 $ 2,671,158 $ 900,303 $ 1,354,538

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Acquisitions	Acquisitions On June 4, 2020, we completed our acquisition of Mathway, LLC (Mathway), an online, on-demand math problem solving company that provides a vast range of subject areas in mathematics, including pre-algebra, algebra, trigonometry, pre-calculus, calculus, and linear algebra, and related disciplines. This acquisition helps to strengthen our existing Chegg Math Solver service with the addition of new subjects, languages, and international reach. The total fair value of the purchase consideration was $101.0 million, of which $93.5 million was paid in cash on the acquisition date and $7.5 million, included within other long-term liabilities, was held in escrow as security for general representations and warranties and potential post-closing adjustments. Any remaining escrow amount will be released 15 months after the acquisition date. The Mathway purchase agreement provides for additional payments of up to $15.0 million subject to the achievement of specified milestones and continued employment of the sellers. These payments are not included in the fair value of the purchase consideration but rather are expensed ratably as acquisition-related compensation costs classified as research and development and general and administrative expenses, based on the seller's job function, on our condensed consolidated statement of operations. We have recorded approximately $1.7 million as of September 30, 2020, included within accrued liabilities on our condensed consolidated balance sheet for these payments. The following table presents the preliminary total allocation of purchase consideration recorded on our condensed consolidated balance sheet as of the acquisition date (in thousands): Mathway Cash $ 712 Accounts receivable 1,132 Other acquired assets 779 Acquired intangible assets 30,320 Total identifiable assets acquired 32,943 Deferred revenue (1,423) Liabilities assumed (727) Net identifiable assets acquired 30,793 Goodwill 70,167 Total fair value of purchase consideration $ 100,960 Goodwill is primarily attributable to the potential for enhancing our existing offerings and expanding our reach by providing additional mathematics support for students and helping them through their academic journey. The amounts recorded for intangible assets and goodwill are deductible for tax purposes. The following table presents the details of the allocation of purchase consideration to the acquired intangible assets (in thousands, except weighted-average amortization period): Mathway Amount Weighted-Average Amortization Period (in months) Domain names $ 220 18 Trade name 520 18 Customer lists 6,220 48 Developed technology 23,360 84 Total acquired intangible assets $ 30,320 75 During the nine months ended September 30, 2020, we incurred $3.1 million of acquisition-related expenses associated with our acquisition of Mathway, which have been included in general and administrative expense on our condensed consolidated statement of operations. We have recorded immaterial amounts of revenue and earnings from Mathway since the acquisition date. The following unaudited supplemental pro forma net loss is for informational purposes only and presents our combined results as if the acquisition of Mathway had occurred on January 1, 2019. The unaudited supplemental pro forma information includes the historical combined operating results adjusted for acquisition-related compensation costs, amortization of intangible assets, share-based compensation expense and acquisition-related expenses and does not necessarily reflect the actual results that would have been achieved, nor is it necessarily indicative of our future consolidated results. During the three and nine months ended September 30, 2020, our supplemental pro forma net loss would have been $37.3 million and $32.3 million, respectively. During the three and nine months ended September 30, 2019, our supplemental pro forma net loss would have been $14.1 million and $33.3 million, respectively. Revenues from Mathway were immaterial during the three and nine months ended September 30, 2020 and 2019 and therefore we have not presented pro forma revenues.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill consists of the following (in thousands): Nine Months Ended September 30, 2020 Year Ended December 31, 2019 Beginning balance $ 214,513 $ 149,524 Additions due to acquisitions 70,167 65,181 Foreign currency translation adjustment 417 (192) Measurement period adjustments related to prior acquisition (288) — Ending balance $ 284,809 $ 214,513 Intangible assets consist of the following (in thousands, except weighted-average amortization period): September 30, 2020 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies and content library 72 $ 66,628 $ (25,392) $ 41,236 Customer lists 47 16,190 (9,718) 6,472 Trade and domain names 44 11,613 (7,467) 4,146 Non-compete agreements 31 2,018 (1,962) 56 Indefinite-lived trade name — 3,600 — 3,600 Foreign currency translation adjustment — (124) — (124) Total intangible assets 64 $ 99,925 $ (44,539) $ 55,386 December 31, 2019 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies and content library 66 $ 43,268 $ (18,395) $ 24,873 Customer lists 47 9,970 (8,210) 1,760 Trade and domain names 46 10,873 (6,169) 4,704 Non-compete agreements 31 2,018 (1,890) 128 Indefinite-lived trade name — 3,600 — 3,600 Foreign currency translation adjustment — (398) — (398) Total intangible assets 58 $ 69,331 $ (34,664) $ 34,667 During the three and nine months ended September 30, 2020, amortization expense related to our finite-lived intangible assets totaled approximately $4.4 million and $9.9 million, respectively. During the three and nine months ended September 30, 2019, amortization expense related to our finite-lived intangible assets totaled approximately $1.5 million and $5.0 million, respectively. As of September 30, 2020, the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands): Remaining three months of 2020 $ 4,404 2021 13,320 2022 10,889 2023 8,760 2024 5,707 Thereafter 8,706 Total $ 51,786

Convertible Senior Notes

Convertible Senior Notes	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Convertible Senior Notes	Convertible Senior NotesIn August 2020, we issued $1.0 billion in aggregate principal amount of 0% convertible senior notes due in 2026 (2026 notes). The aggregate principal amount of the 2026 notes includes $100 million from the initial purchasers fully exercising their option to purchase additional notes. In March 2019, we issued $700 million in aggregate principal amount of 0.125% convertible senior notes due in 2025 (2025 notes) and in April 2019, the initial purchasers fully exercised their option to purchase $100 million of additional 2025 notes for aggregate total principal amount of $800 million. In April 2018, we issued $345 million in aggregate principal amount of 0.25% convertible senior notes due in 2023 (2023 notes). The aggregate principal amount of the 2023 notes includes $45 million from the initial purchasers fully exercising their option to purchase additional notes. The notes were issued in private placements to qualified institutional buyers pursuant to Rule 144A of the Securities Act of 1933, as amended. Concurrently with the offering of the 2026 notes, 2025 notes and 2023 notes, we used $103.4 million, $97.2 million and $39.2 million, respectively, of the net proceeds to enter into privately negotiated capped call transactions. The total net proceeds from the notes are as follows (in thousands): 2026 Notes 2025 Notes 2023 Notes Principal amount $ 1,000,000 $ 800,000 $ 345,000 Less initial purchasers’ discount (15,000) (18,998) (8,625) Less other issuance costs (904) (822) (757) Net proceeds $ 984,096 $ 780,180 $ 335,618 In connection with our issuance of the 2026 notes, we exchanged $172.0 million aggregate principal amount of the 2023 notes in privately-negotiated transactions for an aggregate consideration of $501.7 million, consisting of $174.6 million in cash and 4,182,320 shares of our common stock with a value of $327.1 million. Of the $501.7 million consideration, we allocated $156.1 million and $345.6 million to the liability and equity components of the exchanged 2023 notes, respectively. The fair value of the liability component was calculated by measuring the fair value of similar debt instruments that do not have an associated convertible feature. The carrying amount of the liability component of the 2023 notes subject to the exchange was $152.8 million resulting in a $3.3 million loss on early extinguishment of debt which was recorded in other (expense) income, net in our condensed consolidated statements of operations. Additionally, we terminated 2023 notes capped call transactions underlying 6,380,815 shares of our common stock and received cash proceeds of $57.4 million. As of September 30, 2020, $173.0 million of aggregate principal amount of the 2023 notes remain outstanding and 6,419,850 shares remain underlying the 2023 notes capped call transactions. The notes are our senior, unsecured obligations and are governed by indenture agreements by and between us and Wells Fargo Bank, National Association, as Trustee (the indentures). The 2026 notes bear no interest and will mature on September 1, 2026, unless repurchased, redeemed or converted in accordance with their terms prior to such date. The 2025 notes bear interest of 0.125% per year which is payable semi-annually in arrears on March 15 and September 15 of each year, beginning on September 15, 2019. The 2025 notes will mature on March 15, 2025, unless repurchased, redeemed or converted in accordance with their terms prior to such date. The 2023 notes 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 2023 notes will mature on May 15, 2023, unless repurchased, redeemed or converted in accordance with their terms prior to such date. Each $1,000 principal amount of the 2026 notes will initially be convertible into 9.2978 shares of our common stock. This is equivalent to an initial conversion price of approximately $107.55 per share, which is subject to adjustment in certain circumstances. Each $1,000 principal amount of the 2025 notes will initially be convertible into 19.3956 shares of our common stock. This is equivalent to an initial conversion price of approximately $51.56 per share, which is subject to adjustment in certain circumstances. Each $1,000 principal amount of the 2023 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 June 1, 2026 for the 2026 notes, December 15, 2024 for the 2025 notes and February 15, 2023 for the 2023 notes, 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 December 31, 2020 for the 2026 notes, June 30, 2019 for the 2025 notes, and June 30, 2018 for the 2023 notes, 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 respective conversion price for the notes on each applicable trading day; • during the five-business day period after any 10 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 indentures. On or after June 1, 2026 for the 2026 notes, December 15, 2024 for the 2025 notes and February 15, 2023 for the 2023 notes until the close of business on the second scheduled trading day immediately preceding the respective maturity dates, 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 indentures, prior to the respective maturity dates, 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 indentures, occur prior to the respective maturity dates, we will also increase the conversion rate for a holder who elects to convert their notes in connection with such specified corporate events. The conditions allowing holders of the 2026 notes to convert were not met and therefore the 2026 notes are not convertible. The first circumstance allowing holders of the 2025 notes to convert was met during the three months ended September 30, 2020 and therefore, the 2025 notes are convertible starting October 1, 2020 through December 31, 2020. The first circumstance allowing holders of the 2023 notes to convert was met during the three months ended September 30, 2020, June 30, 2020, March 31, 2020, December 31, 2019, June 30, 2019, and March 31, 2019 and therefore, the 2023 notes were and are convertible starting April 1, 2019 through September 30, 2019 and from January 1, 2020 through December 31, 2020. During the three and nine months ended September 30, 2020, aside from the exchange of $172.0 million aggregate principal amount of the 2023 notes discussed above, we received immaterial requests for conversion of the 2023 notes which we settled in cash during the three and nine months ended September 30, 2020. In accounting for their issuance, we separated the notes into liability and equity components. The carrying amount of the liability components for the 2026 notes, 2025 notes and 2023 notes of approximately $758.7 million, $588.0 million and $280.8 million, respectively, 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 components for the 2026 notes, 2025 notes and 2023 notes of approximately $241.3 million, $212.0 million and $64.2 million, respectively, representing the conversion option, was determined by deducting the carrying amount of the liability components from the principal amount of the notes. This difference between the principal amount of the notes and the liability components represents the debt discount, presented as a reduction to the notes on our condensed consolidated balance sheets, and is amortized to interest expense using the effective interest method over the remaining term of the notes. The equity components of the notes are included in additional paid-in capital on our condensed consolidated balance sheets and are not remeasured as long as they continue to meet the conditions for equity classification. We incurred issuance costs related to the 2026 notes, 2025 notes and 2023 notes of approximately $15.9 million, $19.8 million, $9.4 million, respectively. 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 notes. Issuance costs attributable to the liability components for the 2026 notes, 2025 notes and 2023 notes of approximately $12.1 million, $14.6 million and $7.6 million, respectively, were recorded as debt issuance cost, presented as a reduction to the notes on our condensed consolidated balance sheets, and are amortized to interest expense using the effective interest method over the term of the notes. The issuance costs attributable to the equity components for the 2026 notes, 2025 notes and 2023 notes were approximately $3.8 million, $5.3 million and $1.7 million, respectively, 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): September 30, 2020 December 31, 2019 2026 Notes 2025 Notes 2023 Notes 2025 Notes 2023 Notes Principal $ 1,000,000 $ 800,000 $ 173,018 $ 800,000 $ 345,000 Unamortized debt discount (236,809) (158,077) (16,484) (184,698) (42,280) Unamortized issuance costs (11,842) (10,862) (1,960) (12,691) (5,028) Net carrying amount (liability) $ 751,349 $ 631,061 $ 154,574 $ 602,611 $ 297,692 The net carrying amount of the equity component of the notes is as follows (in thousands): September 30, 2020 December 31, 2019 2026 Notes 2025 Notes 2023 Notes 2025 Notes 2023 Notes Debt discount for conversion option $ 241,300 $ 212,000 $ 32,193 $ 212,000 $ 64,193 Issuance costs (3,838) (5,253) (877) (5,253) (1,749) Net carrying amount (equity) $ 237,462 $ 206,747 $ 31,316 $ 206,747 $ 62,444 As of September 30, 2020, the remaining lives of the 2026 notes, 2025 notes and 2023 notes were approximately 5.9 years, 4.5 years and 2.6 years, respectively. Based on the closing price of our common stock of $71.44 on September 30, 2020, the if-converted value of the 2026 notes was approximately $664.2 million, which was less than the principal amount of $1.0 billion by approximately $335.8 million, the if-converted value of the 2025 notes was approximately $1,108.5 million, which exceeds the principal amount of $800 million by approximately $308.5 million and the if-converted value of the 2023 notes was approximately $458.6 million, which exceeds the principal amount of $173 million by approximately $285.6 million. The effective interest rates of the liability components for the 2026 notes, 2025 notes and 2023 notes are 4.63%, 5.40% and 4.34%, respectively, and each is based on the interest rate of similar debt instruments, at the time of our offering, that do not have associated convertible features. The following tables set forth the total interest expense recognized related to the notes (in thousands): Three Months Ended September 30, 2020 2019 2026 Notes 2025 Notes 2023 Notes 2025 Notes 2023 Notes Contractual interest expense $ — $ 252 $ 169 $ 252 $ 217 Amortization of debt discount 4,491 8,938 2,458 8,939 3,161 Amortization of issuance costs 225 614 292 614 375 Total interest expense $ 4,716 $ 9,804 $ 2,919 $ 9,805 $ 3,753 Nine Months Ended September 30, 2020 2019 2026 Notes 2025 Notes 2023 Notes 2025 Notes 2023 Notes Contractual interest expense $ — $ 750 $ 599 $ 517 $ 645 Amortization of debt discount 4,491 26,621 8,709 18,363 9,377 Amortization of issuance costs 225 1,829 1,035 1,262 1,112 Total interest expense $ 4,716 $ 29,200 $ 10,343 $ 20,142 $ 11,134 Capped Call Transactions Concurrently with the offering of the 2026 notes, 2025 notes and 2023 notes, we used $103.4 million, $97.2 million and $39.2 million, respectively, 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 automatically exercise upon conversion of the notes and cover 9,297,800, 15,516,480 and 6,419,850 shares of our common stock for the 2026 notes, 2025 notes and 2023 notes, respectively, and are intended to effectively increase the overall conversion price from $107.55 to $156.44 per share for the 2026 notes, $51.56 to $79.32 per share for the 2025 notes and $26.95 to $40.68 per share for the 2023 notes. The effective increase in conversion price as a result of the capped call transactions serves to reduce potential dilution to holders of our common stock and/or offset the cash payments we are required to make in excess of the principal amount of any converted notes. 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 sheets 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.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies 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. On June 18, 2020, we received a Civil Investigative Demand (CID) from the Federal Trade Commission (FTC) to determine whether we may have violated Section 5 of the FTC Act or the Children's Online Privacy Protection Act (COPPA), as they relate to deceptive or unfair acts or practices related to consumer privacy and/or data security. Pursuant to the CID, the FTC has requested responses to interrogatories and the production of documents pertaining to data breach incidents and our data security and privacy practices generally. Efforts are currently underway to collect the documents and information requested after reaching an agreement with the FTC on the order and timing of our responses. On May 12, 2020, we received notice that 15,107 arbitration demands were filed against us by individuals represented by the same legal counsel, each alleging to have suffered more than $25,000 in damages as a result of the 2018 Data Incident. On July 1, 2020, an additional 1,007 arbitration demands were filed by the same counsel. On August 12, 2020, an additional 577 arbitration demands were filed by the same counsel. We dispute that these claimants have a valid basis for seeking arbitration and assert that they have acted in bad faith. We have filed a motion seeking modification of the Court's order to arbitrate. On March 3, 2020, Ingram Hosting Holdings LLC (IHH) filed a complaint in the U.S. District Court for the Middle District of Tennessee alleging that Chegg breached its various contracts with IHH and other Ingram group entities, seeking damages in the amount of $17 million. An answer was filed on March 31, 2020. Chegg and Ingram have now dismissed the litigation after reaching an amicable settlement of the dispute which includes an immaterial undisclosed payment from Ingram. On November 5, 2018, NetSoc, LLC (NetSoc) filed a complaint against us in the U.S. District Court for the Southern District of New York for patent infringement alleging that the Chegg Tutors service infringes U.S. Patent No. 9.978,107 and seeking unspecified compensatory damages. A responsive pleading was filed on February 19, 2019. On January 13, 2020, the Court issued an order dismissing the case as to Chegg. On January 30, 2020, NetSoc appealed the dismissal. On April 21, 2020, the Court granted Chegg's motion to hold the appeal in abeyance pending outcome of an appeal in the litigation above.

Guarantees and Indemnifications

Guarantees and Indemnifications	9 Months Ended
	Sep. 30, 2020
Guarantees And Indemnifications [Abstract]
Guarantees and Indemnifications	Guarantees and Indemnifications We have agreed to indemnify our directors and officers for certain events or occurrences, subject to certain limits, while such persons are or were serving at our request in such capacity. We may terminate the indemnification agreements with these persons upon termination of employment, but termination will not affect claims for indemnification related to events occurring prior to the effective date of termination. We have a directors’ and officers’ insurance policy that limits our potential exposure up to the limits of our insurance coverage. In addition, we also have other indemnification agreements with various vendors against certain claims, liabilities, losses, and damages. The maximum amount of potential future indemnification is unlimited. We believe the fair value of these indemnification agreements is minimal. We have not recorded any liabilities for these agreements as of September 30, 2020.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Stockholders' Equity	Stockholders' Equity Securities Repurchase Program In June 2020, our board of directors approved a securities repurchase program pursuant to which we may, from time to time, repurchase up to $500.0 million of our common stock and/or convertible notes, through open market purchases, block trades, and/or privately negotiated transactions or pursuant to Rule 10b5-1 plans, in compliance with applicable securities laws and other legal requirements. The timing, volume, and nature of the repurchases will be determined by management based on the capital needs of the business, market conditions, applicable legal requirements, and other factors. The repurchase program will end on December 31, 2021. There were no securities repurchased during the three months ended September 30, 2020. Share-based Compensation Expense Total share-based compensation expense recorded for employees and non-employees is as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Cost of revenues $ 262 $ 96 $ 644 $ 295 Research and development 8,433 5,741 23,044 15,876 Sales and marketing 2,431 1,843 7,053 5,405 General and administrative 10,403 9,185 28,668 25,779 Total share-based compensation expense $ 21,529 $ 16,865 $ 59,409 $ 47,355 RSU and PSU Activity Activity for RSUs and PSUs is as follows: RSUs and PSUs Outstanding Shares Outstanding Weighted Average Grant Date Fair Value Balance at December 31, 2019 6,909,530 $ 24.04 Granted 2,462,160 43.54 Released (3,591,076) 18.89 Canceled (409,544) 30.57 Balance at September 30, 2020 5,371,070 $ 35.92 As of September 30, 2020, our total unrecognized share-based compensation expense related to RSUs and PSUs was approximately $122.8 million, which will be recognized over the remaining weighted-average vesting period of approximately 2.0 years.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income TaxesWe recorded an income tax provision of approximately $1.1 million and $2.9 million during the three and nine months ended September 30, 2020, respectively, primarily due to state and foreign income tax expense. We recorded an income tax provision of approximately $0.6 million and $1.8 million during the three and nine months ended September 30, 2019, respectively, primarily due to state and foreign income tax expense.

Related-Party Transactions

Related-Party Transactions	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Related-Party Transactions	Related-Party TransactionsOur Chief Executive Officer is a member of the Board of Directors of Adobe Systems Incorporated (Adobe). During the three and nine months ended September 30, 2020, we purchased $0.3 million and $1.1 million, respectively, and during the three and nine months ended September 30, 2019, we purchased $0.4 million and $1.9 million, respectively, of services from Adobe. We had no revenues during the three months ended September 30, 2020 and $0.1 million of revenues during the nine months ended September 30, 2020 from Adobe. We had no revenues during the three and nine months ended September 30, 2019 from Adobe. We had $0.1 million and $0.2 million of payables as of September 30, 2020 and December 31, 2019, respectively, to Adobe. We had no outstanding receivables as of September 30, 2020 and December 31, 2019 from Adobe. The immediate family of one of our board members is a member of the Board of Directors of PayPal Holdings, Inc. (PayPal). During the three and nine months ended September 30, 2020, we incurred payment processing fees of $0.5 million and $1.5 million, respectively, and during the three and nine months ended September 30, 2019, we incurred payment processing fees of $0.4 million and $1.2 million, respectively, to PayPal. One of our board members is also a member of the Board of Directors of Synack, Inc. (Synack). We had no purchases of services from Synack during the three months ended September 30, 2020 and $0.1 million during the nine months ended September 30, 2020. During the three and nine months ended September 30, 2019, we purchased $0.1 million and $0.4 million, respectively, of services from Synack.

Background and Basis of Prese_2

Background and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated balance sheet as of September 30, 2020, the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss, and the condensed consolidated statements of stockholder's equity for the three and nine months ended September 30, 2020 and 2019, and the condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019, and the related footnote disclosures are unaudited. In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all adjustments, including normal recurring adjustments, necessary to present fairly our financial position as of September 30, 2020, our results of operations, results of comprehensive loss, and stockholder's equity for the three and nine months ended September 30, 2020 and 2019, and cash flows for the nine months ended September 30, 2020 and 2019. Our results of operations, results of comprehensive loss, stockholder's equity, and cash flows for the nine months ended September 30, 2020 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, 2019 as 2019. 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, 2019 (the Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). Except for our policies on investments, textbook library, convertible senior notes, net, revenue recognition and deferred revenue, and cost of revenues, 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.
Investments	InvestmentsWe hold investments in commercial paper, corporate debt securities, U.S. treasury securities, and agency bonds. We classify our investments as available-for-sale based on the nature of each security that are either short or long-term based on the remaining contractual maturity of the investment. Our available-for-sale investments are carried at estimated fair value with any unrealized gains and losses unrelated to credit loss factors, net of taxes, included in other comprehensive (loss) income in our condensed consolidated statements of stockholders’ equity. Beginning in 2020, unrealized losses related to credit loss factors are now recorded through an allowance for credit losses in other (expense) income, net in our condensed consolidated statements of operations, rather than as a reduction to the amortized cost basis in other comprehensive (loss) income, when a decline in fair value has resulted from a credit loss. We determine realized gains or losses on the sale of investments on a specific identification method, and record such gains or losses as other (expense) income, net in our condensed consolidated statements of operations.
Textbook Library	Textbook Library Beginning in January 2020, we began our transition back to print textbook ownership by purchasing print textbooks to establish our textbook library. We consider our print textbook library to be a long-term productive asset and, as such, classify it as a non-current asset in our condensed consolidated balance sheets. All print textbooks in our textbook library are stated at cost, which includes the purchase price less accumulated depreciation. We write down textbooks on a book-by-book basis for lost, damaged, or excess print textbooks. We depreciate our print textbooks, less an estimated salvage value, over an estimated useful life of four years using an accelerated method of depreciation, as we estimate this method most accurately reflects the actual pattern of decline in their economic value. The salvage value considers the historical trend and projected proceeds for print textbooks. The useful life is determined based on the estimated time period in which the print textbooks are held and rented. We review the estimated salvage value and useful life of our print textbook library on an ongoing basis. Write-downs for print textbooks, print textbook depreciation expense, the gain or loss on print textbooks liquidated, and the net book value of print textbooks purchased by students at the end of the term or on a just-in-time basis are recorded in cost of revenues in our condensed consolidated statements of operations and classified as adjustments to cash flows from operating activities. Cash outflows for the acquisition of print textbooks net of changes in related accounts payable and accrued liabilities, and cash inflows received from the proceeds from the disposition of print textbooks net of changes in related accounts receivable, are classified as cash flows from investing activities in our condensed consolidated statements of cash flows.
Convertible Senior Notes, net	Convertible Senior Notes, net In August 2020, we issued $1.0 billion in aggregate principal amount of 0% convertible senior notes due in 2026 (2026 notes). In March 2019, we issued $700 million in aggregate principal amount of 0.125% convertible senior notes due in 2025 (2025 notes) and in April 2019, the initial purchasers fully exercised their option to purchase $100 million of additional 2025 notes for aggregate total gross proceeds of $800 million. In April 2018, we issued $345 million in aggregate principal amount of 0.25% convertible senior notes due in 2023 (2023 notes). Collectively, the 2026 notes, 2025 notes, and the 2023 notes are referred to as the “notes.” In accounting for their issuance, we separated the notes into liability and equity components, as the notes represent convertible instruments with a cash conversion feature. 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 consolidated balance sheet, and is amortized to interest expense over the term of the notes using the effective interest rate method. The carrying amount of the liability component is classified as a long-term liability as we have the election to settle conversion requests in shares of our common stock. The carrying amount of 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. In accounting for extinguishment of the notes, we allocated the consideration transferred between the liability and equity components in a similar manner as upon issuance. The liability component for extinguished notes is then compared to the carrying amount of the respective extinguished notes and a gain or loss is recorded in other (expense) income, net in our condensed consolidated statements of operations.
Revenue Recognition and Deferred Revenue	Revenue Recognition and Deferred Revenue We recognize revenues when the control of 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. 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. 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 which primarily includes Chegg Study, Chegg Writing, Chegg Tutors, Chegg Math Solver, Thinkful, and Mathway. Revenues from Chegg Study, Chegg Writing, Chegg Tutors, Chegg Math Solver, and Mathway are primarily recognized ratably over the respective weekly or monthly subscription period. Revenues from Thinkful, our skills-based learning platform, are recognized either ratably over the term of the course, generally six months, or upon completion of the lessons, depending on the instruction type of the course. Revenues from our Required Materials product line includes revenues from print textbooks that we own or that are owned by a partner as well as revenues from eTextbooks. Beginning in 2020, our Required Materials product line includes operating leases with students for the rental of print textbooks that we own. Operating lease income is recognized as the total transaction amount, paid upon commencement of the lease, ratably over the lease term which is generally a two two Some of our customer arrangements 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 multiple performance obligations, we allocate the transaction price based on the relative standalone selling price (SSP) method by comparing the 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. Some of our customer arrangements may include 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. 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. 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. In relation to print textbooks owned by a partner, we recognize revenues on a net basis based on our role in the transaction as an agent as we have concluded that we do not control the use of the print textbooks, and therefore record only the net revenue share we earn. We have concluded that we control our Chegg Services, print textbooks that we own for rental, purchase at the end of the rental term, or sale on a just-in-time basis, and eTextbook service and therefore we recognize revenues and cost of revenues on a gross basis. Contract assets are contained within other current assets and other 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 rental and subscription performance obligations that have not been satisfied and estimated variable consideration. Deferred revenue related to rental and subscription performance obligations 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. Deferred revenue related to variable consideration is recognized as revenues during each reporting period based on the estimated amount we believe we will earn over the life of the contract.
Lessor, Leases	Beginning in 2020, our Required Materials product line includes operating leases with students for the rental of print textbooks that we own. Operating lease income is recognized as the total transaction amount, paid upon commencement of the lease, ratably over the lease term which is generally a two
Cost of Revenues	Cost of Revenues Our cost of revenues consists primarily of expenses associated with the delivery and distribution of our products and services. Cost of revenues primarily consists of publisher content fees for eTextbooks, content amortization expense related to content that we develop, licenses from publishers for which we pay one-time license fees, or acquire through acquisitions, write-downs for print textbooks, the gain or loss on print textbooks liquidated, the net book value of print textbooks purchased by students at the end of the term or on a just-in-time basis, print textbook depreciation expense, payment processing costs, the payments made to tutors through our Chegg Tutors service, personnel costs and other direct costs related to providing products or services. In addition, cost of revenues includes allocated information technology and facilities costs.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States requires management to make estimates, judgments, and assumptions that affect the reported amounts of assets and liabilities; the disclosure of contingent liabilities at the date of the financial statements; and the reported amounts of revenues and expenses during the reporting periods. Significant estimates, assumptions, and judgments are used for, but not limited to: revenue recognition, recoverability of accounts receivable, share-based compensation expense including estimated forfeitures, accounting for income taxes, textbook library, useful lives assigned to long-lived assets for depreciation and amortization, impairment of goodwill and long-lived assets, the valuation of acquired intangible assets, the valuation of our convertible senior notes, internal-use software and website development costs, operating lease right of use (ROU) assets, and operating lease liabilities. 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 August 2020, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2020-06, Accounting for Convertible Instruments and Contracts in an Entity's Own Equity . ASU 2020-06 simplifies the guidance in Accounting Standards Codification (ASC) 470-20, Debt - Debt with Conversion and Other Options, by reducing the number of accounting separation models for convertible instruments, amends the guidance in ASC 815-40, Derivatives and Hedging - Contracts in Entity's Own Equity, for certain contracts in an entity's own equity that are currently accounted for as derivatives, and requires entities to use the if-converted method for all convertible instruments in the diluted earnings per share (EPS) calculation. Early adoption is permitted, but no earlier than annual periods beginning after December 15, 2020, and the guidance allows for a modified retrospective or fully retrospective method of transition. We currently plan to adopt the guidance on January 1, 2021. At this time, we are continuing to refine the quantitative impact of early adopting this guidance and we initially believe the most significant impacts will be an increase in liabilities on our condensed consolidated balance sheets as a result of removing the accounting separation model for convertible instruments with a cash conversion feature, a significant reduction of non-cash interest expense on our condensed consolidated statements of operations, and an increase in the number of shares included in our diluted EPS calculations. We will continue to evaluate the impacts of this guidance, including method of transition, as we near our adoption date. In March 2020, the FASB issued ASU 2020-04, Facilitation of the Effects of Reference Rate Reform on Financial Reporting . ASU 2020-04 provides temporary optional expedients and exceptions for applying reference rate reform to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The guidance can be applied immediately and only applies to contract modifications made or hedging relationships entered into or evaluated before December 31, 2022. While we do not have any hedging relationships and currently do not believe we have material contracts impacted by reference rate reform, we are in the process of evaluating the impact of this guidance. Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. ASU 2019-12 key changes include hybrid tax regimes, intraperiod tax allocation exception, and interim-period accounting for enacted changes in tax law. We early adopted ASU 2019-12 during the second quarter of 2020 under the prospective method of adoption. As a result of adoption, there was no modification required to the first quarter of 2020 results of operations as previously presented. The FASB issued four ASUs related to ASC 326, Financial Instruments - Credit Losses . In November 2019, the FASB issued ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments - Credit Losses. In May 2019, the FASB issued ASU 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief. In April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . On January 1, 2020, we adopted ASC 326, which replaces the existing incurred loss impairment model for financial assets, including trade receivables, with an expected loss model which requires the use of forward-looking information to calculate expected credit loss estimates. Additionally, the concept of other-than-temporary impairment for available-for-sale investments is eliminated and instead requires us to focus on determining whether any unrealized loss is a result of a credit loss or other factors. We adopted ASC 326 under the modified retrospective method for all financial assets measured at amortized cost. Results for reporting periods beginning after adoption are presented under ASC 326 while we have not changed previously disclosed amounts or provided additional disclosures for comparative periods. We recorded an immaterial cumulative-effect adjustment to trade receivables to the opening balance of accumulated deficit in our condensed consolidated balance sheet. We adopted ASC 326 under the prospective transition approach for available-for-sale investments which resulted in no change to amortized cost basis before and after adoption. Credit losses related to available-for-sale investments will now be recorded through an allowance for credit losses with immediate recognition to our condensed consolidated statement of operations rather than as a reduction to the amortized cost basis and recognition to our condensed consolidated statements of comprehensive loss. See above within Note 1, “Background and Basis of Presentation”, for updates to our significant accounting policies impacted by our adoption of ASC 326 as well as Note 4, “Cash and Cash Equivalents, and Investments” for more information. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with existing guidance contained within subtopic 350-40 to develop or obtain internal-use software. We adopted ASU 2018-15 on January 1, 2020 under the prospective method of adoption.
Net Loss Per Share	Net Loss Per ShareBasic 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, restricted stock units (RSUs), performance-based restricted stock units (PSUs), and shares related to convertible senior notes, 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)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following tables set 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 September 30, Change 2020 2019 $ % Chegg Services $ 118,895 $ 69,304 $ 49,591 72 % Required Materials 35,123 24,847 10,276 41 Total net revenues $ 154,018 $ 94,151 $ 59,867 64 Nine Months Ended September 30, Change 2020 2019 $ % Chegg Services $ 345,258 $ 224,903 $ 120,355 54 % Required Materials 93,359 60,519 32,840 54 Total net revenues $ 438,617 $ 285,422 $ 153,195 54
Schedule of Accounts Receivable	The following table presents our accounts receivable, net, deferred revenue, and contract assets balances (in thousands, except percentages): Change September 30, 2020 December 31, 2019 $ % Accounts receivable, net $ 12,487 $ 11,529 $ 958 8 % Deferred revenue 51,941 18,780 33,161 177 Contract assets 8,214 3,531 4,683 133

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the computation of basic and diluted net loss per share (in thousands, except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator: Net loss $ (37,140) $ (11,477) $ (32,264) $ (17,824) Denominator: Weighted average shares used to compute net loss per share, basic and diluted 126,194 120,085 124,162 118,547 Net loss per share, basic and diluted $ (0.29) $ (0.10) $ (0.26) $ (0.15)
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 September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Options to purchase common stock 865 2,122 977 2,715 RSUs and PSUs 3,394 3,831 3,425 4,952 Shares related to convertible senior notes 8,721 4,098 4,422 3,709 Employee stock purchase plan 9 7 4 3 Total common stock equivalents 12,989 10,058 8,828 11,379

Cash and Cash Equivalents, an_2

Cash and Cash Equivalents, and Investments (Tables)	9 Months Ended
	Sep. 30, 2020
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Investments	The following tables show our cash and cash equivalents, and investments’ adjusted cost, unrealized gain, unrealized loss, and fair value as of September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 17,346 $ — $ — $ 17,346 U.S. treasury securities 307,673 — — 307,673 Money market funds 202,522 — — 202,522 Total cash and cash equivalents $ 527,541 $ — $ — $ 527,541 Short-term investments: Commercial paper $ 204,044 $ 38 $ (24) $ 204,058 Corporate securities 516,682 2,644 (57) 519,269 Total short-term investments $ 720,726 $ 2,682 $ (81) $ 723,327 Long-term investments: Corporate securities $ 456,774 $ 602 $ (635) $ 456,741 Agency bonds 64,495 25 — 64,520 Total long-term investments $ 521,269 $ 627 $ (635) $ 521,261 December 31, 2019 Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 241,355 $ — $ — $ 241,355 Money market funds 146,165 — — 146,165 Total cash and cash equivalents $ 387,520 $ — $ — $ 387,520 Short-term investments: Commercial paper $ 7,489 $ — $ — $ 7,489 Corporate securities 318,946 425 (78) 319,293 U.S. treasury securities 44,251 39 (4) 44,286 Agency bonds 10,000 6 — 10,006 Total short-term investments $ 380,686 $ 470 $ (82) $ 381,074 Long-term investments: Corporate securities $ 295,103 $ 533 $ (158) $ 295,478 Agency bonds 14,999 6 — 15,005 Total long-term investments $ 310,102 $ 539 $ (158) $ 310,483
Schedule of Available-for-sale Securities Reconciliation	The following table shows our cash equivalents and investments' adjusted cost and fair value by contractual maturity as of September 30, 2020 (in thousands): Adjusted Cost Fair Value Due in 1 year or less $ 1,028,399 $ 1,031,000 Due in 1-2 years 521,269 521,261 Investments not due at a single maturity date 202,522 202,522 Total $ 1,752,190 $ 1,754,783

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Financial instruments measured and recorded at fair value on a recurring basis as of September 30, 2020 and December 31, 2019 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2020 Total Level 1 Level 2 Assets: Cash equivalents: U.S. treasury securities $ 307,673 $ 307,673 $ — Money market funds 202,522 202,522 — Short-term investments: Commercial paper 204,058 — 204,058 Corporate securities 519,269 — 519,269 Long-term investments: Corporate securities 456,741 — 456,741 Agency bonds 64,520 — 64,520 Total assets measured and recorded at fair value $ 1,754,783 $ 510,195 $ 1,244,588 December 31, 2019 Total Level 1 Level 2 Assets: Cash equivalents: Money market funds $ 146,165 $ 146,165 $ — Short-term investments: Commercial paper 7,489 — 7,489 Corporate securities 319,293 — 319,293 U.S. treasury securities 44,286 44,286 — Agency bonds 10,006 — 10,006 Long-term investments: Corporate securities 295,478 — 295,478 Agency bonds 15,005 — 15,005 Total assets measured and recorded at fair value $ 837,722 $ 190,451 $ 647,271
Fair Value Measurements, Nonrecurring	The carrying amounts and estimated fair values of the notes as of September 30, 2020 and December 31, 2019 are as follows (in thousands): September 30, 2020 December 31, 2019 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value 2026 notes $ 751,349 $ 1,000,000 $ — $ — 2025 notes 631,061 1,208,800 602,611 831,000 2023 notes 154,574 462,358 297,692 523,538 Convertible senior notes, net $ 1,536,984 $ 2,671,158 $ 900,303 $ 1,354,538

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table presents the preliminary total allocation of purchase consideration recorded on our condensed consolidated balance sheet as of the acquisition date (in thousands): Mathway Cash $ 712 Accounts receivable 1,132 Other acquired assets 779 Acquired intangible assets 30,320 Total identifiable assets acquired 32,943 Deferred revenue (1,423) Liabilities assumed (727) Net identifiable assets acquired 30,793 Goodwill 70,167 Total fair value of purchase consideration $ 100,960
Schedule Of Allocation Of Purchase Consideration To Acquired Intangible Assets	The following table presents the details of the allocation of purchase consideration to the acquired intangible assets (in thousands, except weighted-average amortization period): Mathway Amount Weighted-Average Amortization Period (in months) Domain names $ 220 18 Trade name 520 18 Customer lists 6,220 48 Developed technology 23,360 84 Total acquired intangible assets $ 30,320 75

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Goodwill consists of the following (in thousands): Nine Months Ended September 30, 2020 Year Ended December 31, 2019 Beginning balance $ 214,513 $ 149,524 Additions due to acquisitions 70,167 65,181 Foreign currency translation adjustment 417 (192) Measurement period adjustments related to prior acquisition (288) — Ending balance $ 284,809 $ 214,513
Finite-Lived Intangible Assets	Intangible assets consist of the following (in thousands, except weighted-average amortization period): September 30, 2020 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies and content library 72 $ 66,628 $ (25,392) $ 41,236 Customer lists 47 16,190 (9,718) 6,472 Trade and domain names 44 11,613 (7,467) 4,146 Non-compete agreements 31 2,018 (1,962) 56 Indefinite-lived trade name — 3,600 — 3,600 Foreign currency translation adjustment — (124) — (124) Total intangible assets 64 $ 99,925 $ (44,539) $ 55,386 December 31, 2019 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies and content library 66 $ 43,268 $ (18,395) $ 24,873 Customer lists 47 9,970 (8,210) 1,760 Trade and domain names 46 10,873 (6,169) 4,704 Non-compete agreements 31 2,018 (1,890) 128 Indefinite-lived trade name — 3,600 — 3,600 Foreign currency translation adjustment — (398) — (398) Total intangible assets 58 $ 69,331 $ (34,664) $ 34,667
Indefinite-lived Intangible Assets	Intangible assets consist of the following (in thousands, except weighted-average amortization period): September 30, 2020 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies and content library 72 $ 66,628 $ (25,392) $ 41,236 Customer lists 47 16,190 (9,718) 6,472 Trade and domain names 44 11,613 (7,467) 4,146 Non-compete agreements 31 2,018 (1,962) 56 Indefinite-lived trade name — 3,600 — 3,600 Foreign currency translation adjustment — (124) — (124) Total intangible assets 64 $ 99,925 $ (44,539) $ 55,386 December 31, 2019 Weighted-Average Amortization Period (in months) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technologies and content library 66 $ 43,268 $ (18,395) $ 24,873 Customer lists 47 9,970 (8,210) 1,760 Trade and domain names 46 10,873 (6,169) 4,704 Non-compete agreements 31 2,018 (1,890) 128 Indefinite-lived trade name — 3,600 — 3,600 Foreign currency translation adjustment — (398) — (398) Total intangible assets 58 $ 69,331 $ (34,664) $ 34,667
Estimated Future Amortization Expense Related to Intangible Assets	As of September 30, 2020, the estimated future amortization expense related to our finite-lived intangible assets is as follows (in thousands): Remaining three months of 2020 $ 4,404 2021 13,320 2022 10,889 2023 8,760 2024 5,707 Thereafter 8,706 Total $ 51,786

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The total net proceeds from the notes are as follows (in thousands): 2026 Notes 2025 Notes 2023 Notes Principal amount $ 1,000,000 $ 800,000 $ 345,000 Less initial purchasers’ discount (15,000) (18,998) (8,625) Less other issuance costs (904) (822) (757) Net proceeds $ 984,096 $ 780,180 $ 335,618
Schedule of Debt	The net carrying amount of the liability component of the notes is as follows (in thousands): September 30, 2020 December 31, 2019 2026 Notes 2025 Notes 2023 Notes 2025 Notes 2023 Notes Principal $ 1,000,000 $ 800,000 $ 173,018 $ 800,000 $ 345,000 Unamortized debt discount (236,809) (158,077) (16,484) (184,698) (42,280) Unamortized issuance costs (11,842) (10,862) (1,960) (12,691) (5,028) Net carrying amount (liability) $ 751,349 $ 631,061 $ 154,574 $ 602,611 $ 297,692 The net carrying amount of the equity component of the notes is as follows (in thousands): September 30, 2020 December 31, 2019 2026 Notes 2025 Notes 2023 Notes 2025 Notes 2023 Notes Debt discount for conversion option $ 241,300 $ 212,000 $ 32,193 $ 212,000 $ 64,193 Issuance costs (3,838) (5,253) (877) (5,253) (1,749) Net carrying amount (equity) $ 237,462 $ 206,747 $ 31,316 $ 206,747 $ 62,444
Schedule Of Interest Expense Recognized	The following tables set forth the total interest expense recognized related to the notes (in thousands): Three Months Ended September 30, 2020 2019 2026 Notes 2025 Notes 2023 Notes 2025 Notes 2023 Notes Contractual interest expense $ — $ 252 $ 169 $ 252 $ 217 Amortization of debt discount 4,491 8,938 2,458 8,939 3,161 Amortization of issuance costs 225 614 292 614 375 Total interest expense $ 4,716 $ 9,804 $ 2,919 $ 9,805 $ 3,753 Nine Months Ended September 30, 2020 2019 2026 Notes 2025 Notes 2023 Notes 2025 Notes 2023 Notes Contractual interest expense $ — $ 750 $ 599 $ 517 $ 645 Amortization of debt discount 4,491 26,621 8,709 18,363 9,377 Amortization of issuance costs 225 1,829 1,035 1,262 1,112 Total interest expense $ 4,716 $ 29,200 $ 10,343 $ 20,142 $ 11,134

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [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 September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Cost of revenues $ 262 $ 96 $ 644 $ 295 Research and development 8,433 5,741 23,044 15,876 Sales and marketing 2,431 1,843 7,053 5,405 General and administrative 10,403 9,185 28,668 25,779 Total share-based compensation expense $ 21,529 $ 16,865 $ 59,409 $ 47,355
Summary of Restricted Stock Unit Activity	Activity for RSUs and PSUs is as follows: RSUs and PSUs Outstanding Shares Outstanding Weighted Average Grant Date Fair Value Balance at December 31, 2019 6,909,530 $ 24.04 Granted 2,462,160 43.54 Released (3,591,076) 18.89 Canceled (409,544) 30.57 Balance at September 30, 2020 5,371,070 $ 35.92

Background and Basis of Prese_3

Background and Basis of Presentation (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Textbook library, net	$ 34,575	$ 34,575		$ 0
Print textbook depreciation expense		10,699	$ 0
Gain on textbook library, net		$ (2,028)	$ 0
Textbook Library
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Estimated useful life		4 years
Textbook library, net	34,600	$ 34,600
Property, plant and equipment, gross	44,800	44,800
Accumulated depreciation	(9,200)	(9,200)
Write down		(1,000)
Print textbook depreciation expense	3,600	10,700
Gain on textbook library, net	$ (600)	$ (2,000)
Textbook Library | Minimum
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Contractual period		2 months
Textbook Library | Maximum
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Contractual period		5 months
eTextbooks | Minimum
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Contractual period		2 months
eTextbooks | Maximum
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Contractual period		5 months

Background and Basis of Prese_4

Background and Basis of Presentation - Convertible Notes (Details) - Senior Notes - USD ($)	1 Months Ended
	Aug. 31, 2020	Apr. 30, 2019	Apr. 30, 2018	Sep. 30, 2020	Dec. 31, 2019	Mar. 31, 2019
0% Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Face value	$ 1,000,000,000			$ 1,000,000,000
Interest rate, stated percentage	0.00%
Proceeds from issuance of debt	$ 1,000,000,000
0.125% Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Face value		$ 100,000,000		800,000,000	$ 800,000,000	$ 700,000,000
Interest rate, stated percentage						0.125%
Proceeds from issuance of debt		$ 800,000,000
0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Face value			$ 345,000,000	$ 173,018,000	$ 345,000,000
Interest rate, stated percentage			0.25%
Proceeds from issuance of debt			$ 345,000,000

Revenues (Details)

Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total net revenues	$ 154,018	$ 94,151	$ 438,617	$ 285,422
Change in total net revenues	$ 59,867		$ 153,195
Change in total net revenues, percent	64.00%		54.00%
Contract with customer, liability, revenue recognized	$ 25,400	15,700	$ 18,000	16,000
Contract with customer, liability, revenue recognized, prior period		2,200		2,700
Accounts receivable, net	12,487		12,487		$ 11,529
Change in accounts receivable			$ 958
Change in accounts receivable, percent			8.00%
Deferred revenue	51,941		$ 51,941		18,780
Change in deferred revenue			$ 33,161
Change in deferred revenue, percent			177.00%
Contract assets	8,214		$ 8,214		$ 3,531
Change in contract assets			$ 4,683
Change in contract assets, percent			133.00%
Textbook Library
Disaggregation of Revenue [Line Items]
Operating lease income	12,000		$ 35,400
Chegg Services
Disaggregation of Revenue [Line Items]
Total net revenues	118,895	69,304	345,258	224,903
Change in total net revenues	$ 49,591		$ 120,355
Change in total net revenues, percent	72.00%		54.00%
Required Materials
Disaggregation of Revenue [Line Items]
Total net revenues	$ 35,123	$ 24,847	$ 93,359	$ 60,519
Change in total net revenues	$ 10,276		$ 32,840
Change in total net revenues, percent	41.00%		54.00%

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss	$ (37,140)	$ (11,477)	$ (32,264)	$ (17,824)
Denominator:
Weighted average shares used to compute net loss per share, basic and diluted (in shares)	126,194	120,085	124,162	118,547
Net loss per share, basic and diluted (in dollars per share)	$ (0.29)	$ (0.10)	$ (0.26)	$ (0.15)

Net Loss Per Share - Shares Exc

Net Loss Per Share - Shares Excluded From Computation Of Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Apr. 30, 2019	Mar. 31, 2019	Apr. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	12,989	10,058	8,828	11,379
0.25% Convertible Senior Notes Due 2023 | Senior Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Face value	$ 173,018,000		$ 173,018,000		$ 345,000,000			$ 345,000,000
Conversion price	$ 26.95		$ 26.95
0.25% Convertible Senior Notes Due 2023 | Senior Notes | Capped Call
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion price	$ 40.68		$ 40.68
0.125% Convertible Senior Notes Due 2025 | Senior Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Face value	$ 800,000,000		$ 800,000,000		$ 800,000,000	$ 100,000,000	$ 700,000,000
Conversion price	$ 51.56		$ 51.56
0.125% Convertible Senior Notes Due 2025 | Senior Notes | Capped Call
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion price	$ 79.32		$ 79.32
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	865	2,122	977	2,715
RSUs and PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	3,394	3,831	3,425	4,952
Senior Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	8,721	4,098	4,422	3,709
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	9	7	4	3

Cash and Cash Equivalents, an_3

Cash and Cash Equivalents, and Investments - Schedule of Available For Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	$ 1,752,190
Fair Value	1,754,783
Cash and cash equivalents:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	527,541	$ 387,520
Unrealized Gain	0	0
Unrealized Loss	0	0
Fair Value	527,541	387,520
Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	720,726	380,686
Unrealized Gain	2,682	470
Unrealized Loss	(81)	(82)
Fair Value	723,327	381,074
Long-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	521,269	310,102
Unrealized Gain	627	539
Unrealized Loss	(635)	(158)
Fair Value	521,261	310,483
Commercial paper | Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	204,044	7,489
Unrealized Gain	38	0
Unrealized Loss	(24)	0
Fair Value	204,058	7,489
Corporate securities | Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	516,682	318,946
Unrealized Gain	2,644	425
Unrealized Loss	(57)	(78)
Fair Value	519,269	319,293
Corporate securities | Long-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	456,774	295,103
Unrealized Gain	602	533
Unrealized Loss	(635)	(158)
Fair Value	456,741	295,478
U.S. treasury securities | Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost		44,251
Unrealized Gain		39
Unrealized Loss		(4)
Fair Value		44,286
Agency bonds | Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost		10,000
Unrealized Gain		6
Unrealized Loss		0
Fair Value		10,006
Agency bonds | Long-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	64,495	14,999
Unrealized Gain	25	6
Unrealized Loss	0	0
Fair Value	64,520	15,005
Cash | Cash and cash equivalents:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	17,346	241,355
Unrealized Gain	0	0
Unrealized Loss	0	0
Fair Value	17,346	241,355
Money market funds | Cash and cash equivalents:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	202,522	146,165
Unrealized Gain	0	0
Unrealized Loss	0	0
Fair Value	202,522	$ 146,165
U.S. treasury securities | Cash and cash equivalents:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	307,673
Unrealized Gain	0
Unrealized Loss	0
Fair Value	$ 307,673

Cash and Cash Equivalents, an_4

Cash and Cash Equivalents, and Investments - Contractual Maturity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Cash and Cash Equivalents [Abstract]
Due in 1 year or less, Cost	$ 1,028,399
Due in 1-2 years, Cost	521,269
Investments not due at a single maturity date, Cost	202,522
Adjusted Cost	1,752,190
Due in 1 year or less, Fair Value	1,031,000
Due in 1-2 years, Fair Value	521,261
Investments not due at a single maturity date, Fair Value	202,522
Total, Fair Value	$ 1,754,783
Weighted average maturity	12 months

Cash and Cash Equivalents, an_5

Cash and Cash Equivalents, and Investments - Restricted Cash (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Security Deposit For Office
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 2	$ 1.9

Cash and Cash Equivalents, an_6

Cash and Cash Equivalents, and Investments - Strategic Investment (Details) - USD ($) $ in Millions	Jun. 30, 2020	Oct. 31, 2018	Mar. 31, 2017
TAPD, Inc.
Schedule of Investments [Line Items]
Cost method investment	$ 2
WayUp, Inc.
Schedule of Investments [Line Items]
Cost method investment		$ 10
Foreign Entity
Schedule of Investments [Line Items]
Cost method investment			$ 3

Fair Value Measurement - Financ

Fair Value Measurement - Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 723,327	$ 381,074
Long-term investments	521,261	310,483
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	1,754,783	837,722
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	510,195	190,451
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	1,244,588	647,271
Commercial paper | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	204,058	7,489
Commercial paper | Fair Value, Measurements, Recurring | 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 | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	204,058	7,489
Corporate securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	519,269	319,293
Long-term investments	456,741	295,478
Corporate securities | Fair Value, Measurements, Recurring | 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 | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	519,269	319,293
Long-term investments	456,741	295,478
U.S. treasury securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		44,286
U.S. treasury securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		44,286
U.S. treasury securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		0
Agency bonds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		10,006
Long-term investments	64,520	15,005
Agency bonds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		0
Long-term investments	0	0
Agency bonds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		10,006
Long-term investments	64,520	15,005
Money market funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	202,522	146,165
Money market funds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	202,522	146,165
Money market funds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	$ 0
U.S. treasury securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	307,673
U.S. treasury securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	307,673
U.S. treasury securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 0

Fair Value Measurement - Debt (

Fair Value Measurement - Debt (Details) - Senior Notes - USD ($) $ in Thousands	Sep. 30, 2020	Aug. 31, 2020	Dec. 31, 2019	Apr. 30, 2019	Apr. 30, 2018
Carrying Amount | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	$ 1,536,984		$ 900,303
Estimated Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	2,671,158		1,354,538
0% Convertible Senior Notes Due 2026
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unamortized debt discount	236,809
Unamortized issuance costs	11,842	$ 15,900
0% Convertible Senior Notes Due 2026 | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes		758,700
0% Convertible Senior Notes Due 2026 | Carrying Amount | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	751,349		0
0% Convertible Senior Notes Due 2026 | Estimated Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	1,000,000		0
0.125% Convertible Senior Notes Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unamortized debt discount	158,077		184,698
Unamortized issuance costs	10,862		12,691	$ 19,800
0.125% Convertible Senior Notes Due 2025 | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes				$ 588,000
0.125% Convertible Senior Notes Due 2025 | Carrying Amount | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	631,061		602,611
0.125% Convertible Senior Notes Due 2025 | Estimated Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	1,208,800		831,000
0.25% Convertible Senior Notes Due 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes		$ 156,100
Unamortized debt discount	16,484		42,280
Unamortized issuance costs	1,960		5,028		$ 9,400
0.25% Convertible Senior Notes Due 2023 | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes					$ 280,800
0.25% Convertible Senior Notes Due 2023 | Carrying Amount | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	154,574		297,692
0.25% Convertible Senior Notes Due 2023 | Estimated Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	$ 462,358		$ 523,538

Acquisitions (Details)

Acquisitions (Details) - Mathway, LLC - USD ($) $ in Millions	Jun. 04, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Fair value of purchase consideration	$ 101
Initial cash consideration	93.5
Escrow	$ 7.5
Remaining escrow release period	15 months
Contingent payments	$ 15
Contingent consideration, liability		$ 1.7		$ 1.7
Acquisition related costs				3.1
Pro forma net income (loss)		$ (37.3)	$ (14.1)	$ (32.3)	$ (33.3)

Acquisitions - Assets Acquired

Acquisitions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 04, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 284,809		$ 214,513	$ 149,524
Mathway, LLC
Business Acquisition [Line Items]
Cash		$ 712
Accounts receivable		1,132
Other acquired assets		779
Acquired intangible assets		30,320
Total identifiable assets acquired		32,943
Deferred revenue		(1,423)
Liabilities assumed		(727)
Net identifiable assets acquired		30,793
Goodwill		70,167
Total fair value of purchase consideration		$ 100,960

Acquisitions - Intangible Asset

Acquisitions - Intangible Assets (Details) $ in Thousands	Jun. 04, 2020USD ($)
Business Acquisition [Line Items]
Weighted-Average Amortization Period (in months)	75 months
Mathway, LLC
Business Acquisition [Line Items]
Total acquired intangible assets	$ 30,320
Domain names
Business Acquisition [Line Items]
Total acquired intangible assets	$ 220
Weighted-Average Amortization Period (in months)	18 months
Trade and domain names
Business Acquisition [Line Items]
Total acquired intangible assets	$ 520
Weighted-Average Amortization Period (in months)	18 months
Customer lists
Business Acquisition [Line Items]
Total acquired intangible assets	$ 6,220
Weighted-Average Amortization Period (in months)	48 months
Developed technology
Business Acquisition [Line Items]
Total acquired intangible assets	$ 23,360
Weighted-Average Amortization Period (in months)	84 months

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Beginning balance	$ 214,513	$ 149,524
Additions due to acquisitions	70,167	65,181
Foreign currency translation adjustment	417	(192)
Measurement period adjustments related to prior acquisition	(288)	0
Ending balance	$ 284,809	$ 214,513

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Finite-lived and Indefinite-lived Intangibe Assets (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	58 months	64 months
Accumulated Amortization		$ (44,539)	$ (34,664)
Net Carrying Amount		51,786
Indefinite-lived trade name		3,600	3,600
Foreign currency translation adjustment	$ (398)	(124)
Total intangible assets, gross carrying amount		99,925	69,331
Intangible assets, net		$ 55,386	34,667
Developed technologies and content library
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	66 months	72 months
Gross Carrying Amount		$ 66,628	43,268
Accumulated Amortization		(25,392)	(18,395)
Net Carrying Amount		$ 41,236	24,873
Customer lists
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	47 months	47 months
Gross Carrying Amount		$ 16,190	9,970
Accumulated Amortization		(9,718)	(8,210)
Net Carrying Amount		$ 6,472	1,760
Trade and domain names
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	46 months	44 months
Gross Carrying Amount		$ 11,613	10,873
Accumulated Amortization		(7,467)	(6,169)
Net Carrying Amount		$ 4,146	4,704
Non-compete agreements
Finite Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period (in months)	31 months	31 months
Gross Carrying Amount		$ 2,018	2,018
Accumulated Amortization		(1,962)	(1,890)
Net Carrying Amount		$ 56	$ 128

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Acquisition-Related Intangible Assets
Finite Lived Intangible Assets [Line Items]
Amortization expense of acquisition related to acquired intangible assets	$ 4.4	$ 1.5	$ 9.9	$ 5

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Estimated Future Amortization Expense Related to Intangible Assets (Details) $ in Thousands	Sep. 30, 2020USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remaining three months of 2020	$ 4,404
2021	13,320
2022	10,889
2023	8,760
2024	5,707
Thereafter	8,706
Net Carrying Amount	$ 51,786

Convertible Senior Notes (Detai

Convertible Senior Notes (Details)	1 Months Ended			9 Months Ended
	Aug. 31, 2020USD ($)shares	Apr. 30, 2019USD ($)	Apr. 30, 2018USD ($)day	Sep. 30, 2020USD ($)$ / sharesshares	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Mar. 31, 2019USD ($)
Debt Instrument [Line Items]
Net proceeds				$ 984,096,000	$ 780,180,000
Repayments of convertible senior notes				159,677,000	0
Gain (loss) on extinguishment of debt				(3,315,000)	0
Proceeds from exercise of convertible senior notes capped call				$ 57,414,000	$ 0
Senior Notes
Debt Instrument [Line Items]
Share price (in dollars per share) | $ / shares				$ 71.44
Senior Notes | 0% Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Face value	$ 1,000,000,000			$ 1,000,000,000
Interest rate, stated percentage	0.00%
Proceeds from issuance of debt	$ 1,000,000,000
Less initial purchasers’ discount	(15,000,000)
Less other issuance costs	(904,000)
Net proceeds	984,096,000
Debt instrument, equity component	$ 241,300,000			$ 237,462,000
Conversion ratio	0.0092978
Conversion price | $ / shares				$ 107.55
Debt instrument, remaining useful life				5 years 10 months 24 days
Debt conversion, converted instrument, amount				$ 664,200,000
Debt instrument, if-converted value less than principal				(335,800,000)
Interest rate, effective percentage		4.63%
Debt issuance costs	$ (15,900,000)			$ (11,842,000)
Senior Notes | 0% Convertible Senior Notes Due 2026 | Debt Instrument, Liability Component
Debt Instrument [Line Items]
Debt issuance costs	(12,100,000)
Senior Notes | 0% Convertible Senior Notes Due 2026 | Debt Instrument, Equity Component
Debt Instrument [Line Items]
Debt issuance costs	(3,800,000)
Senior Notes | 0% Convertible Senior Notes Due 2026 | Carrying Amount
Debt Instrument [Line Items]
Convertible senior notes	758,700,000
Senior Notes | 0% Convertible Senior Notes Due 2026 | Capped Call
Debt Instrument [Line Items]
Net proceeds	103,400,000
Debt instrument, convertible (in shares) | shares				9,297,800
Conversion price | $ / shares				$ 156.44
Senior Notes | 0% Convertible Senior Notes Due 2026, Additional Notes
Debt Instrument [Line Items]
Face value	100,000,000
Senior Notes | 0.125% Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Face value		$ 100,000,000		$ 800,000,000		$ 800,000,000	$ 700,000,000
Interest rate, stated percentage							0.125%
Proceeds from issuance of debt		800,000,000
Less initial purchasers’ discount		(18,998,000)
Less other issuance costs		(822,000)
Net proceeds		780,180,000
Debt instrument, equity component		$ 212,000,000		$ 206,747,000		206,747,000
Conversion ratio		0.0193956
Conversion price | $ / shares				$ 51.56
Debt instrument, remaining useful life				4 years 6 months
Debt conversion, converted instrument, amount				$ 1,108,500,000
Debt instrument, if-converted value in excess of principal				308,500,000
Interest rate, effective percentage		5.40%
Debt issuance costs		$ (19,800,000)		$ (10,862,000)		(12,691,000)
Senior Notes | 0.125% Convertible Senior Notes Due 2025 | Debt Instrument, Liability Component
Debt Instrument [Line Items]
Debt issuance costs		(14,600,000)
Senior Notes | 0.125% Convertible Senior Notes Due 2025 | Debt Instrument, Equity Component
Debt Instrument [Line Items]
Debt issuance costs		(5,300,000)
Senior Notes | 0.125% Convertible Senior Notes Due 2025 | Carrying Amount
Debt Instrument [Line Items]
Convertible senior notes		588,000,000
Senior Notes | 0.125% Convertible Senior Notes Due 2025 | Capped Call
Debt Instrument [Line Items]
Net proceeds		$ 97,200,000
Debt instrument, convertible (in shares) | shares				15,516,480
Conversion price | $ / shares				$ 79.32
Senior Notes | 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Face value			$ 345,000,000	$ 173,018,000		345,000,000
Interest rate, stated percentage			0.25%
Proceeds from issuance of debt			$ 345,000,000
Less initial purchasers’ discount			(8,625,000)
Less other issuance costs			(757,000)
Net proceeds			335,618,000
Option to purchase additional notes			45,000,000
Repurchased principal amount	172,000,000
Aggregate consideration for principal amount exchanged	501,700,000
Repayments of convertible senior notes	$ 174,600,000
Debt conversion, shares issued (in shares) | shares	4,182,320
Debt conversion, shares issued, value	$ 327,100,000
Convertible senior notes	156,100,000
Debt instrument, equity component	345,600,000		$ 64,200,000	$ 31,316,000		62,444,000
Carrying amount	152,800,000
Gain (loss) on extinguishment of debt	$ (3,300,000)
Conversion ratio			0.0371051
Conversion price | $ / shares				$ 26.95
Debt instrument, remaining useful life				2 years 7 months 6 days
Debt conversion, converted instrument, amount				$ 458,600,000
Debt instrument, if-converted value in excess of principal				285,600,000
Interest rate, effective percentage			4.34%
Debt issuance costs			$ (9,400,000)	$ (1,960,000)		$ (5,028,000)
Senior Notes | 0.25% Convertible Senior Notes Due 2023 | Debt Instrument, Liability Component
Debt Instrument [Line Items]
Debt issuance costs			(7,600,000)
Senior Notes | 0.25% Convertible Senior Notes Due 2023 | Debt Instrument, Equity Component
Debt Instrument [Line Items]
Debt issuance costs			(1,700,000)
Senior Notes | 0.25% Convertible Senior Notes Due 2023 | Carrying Amount
Debt Instrument [Line Items]
Convertible senior notes			$ 280,800,000
Senior Notes | 0.25% Convertible Senior Notes Due 2023 | Sale Price Is Greater Or Equal 130%
Debt Instrument [Line Items]
Threshold trading days | day			20
Threshold consecutive trading days | day			30
Threshold percentage of stock price trigger			130.00%
Senior Notes | 0.25% Convertible Senior Notes Due 2023 | Trading Price Per $1,000 Principal Amount Less Than 98%
Debt Instrument [Line Items]
Threshold trading days | day			5
Threshold consecutive trading days | day			10
Senior Notes | 0.25% Convertible Senior Notes Due 2023 | Trading Price Per $1,000 Principal Amount Less Than 98% | Maximum
Debt Instrument [Line Items]
Threshold percentage of stock price trigger			98.00%
Senior Notes | 0.25% Convertible Senior Notes Due 2023 | Capped Call
Debt Instrument [Line Items]
Net proceeds			$ 39,200,000
Debt instrument, convertible, shares terminated (in shares) | shares	6,380,815
Proceeds from exercise of convertible senior notes capped call	$ 57,400,000
Debt instrument, convertible (in shares) | shares				6,419,850
Conversion price | $ / shares				$ 40.68

Convertible Senior Notes - Net

Convertible Senior Notes - Net Carrying Amount (Details) - Senior Notes - USD ($)	Sep. 30, 2020	Aug. 31, 2020	Dec. 31, 2019	Apr. 30, 2019	Mar. 31, 2019	Apr. 30, 2018
0% Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Principal	$ 1,000,000,000	$ 1,000,000,000
Unamortized debt discount	(236,809,000)
Unamortized issuance costs	(11,842,000)	(15,900,000)
Debt discount for conversion option	241,300,000
Issuance costs	(3,838,000)
Net carrying amount (equity)	237,462,000	241,300,000
0.125% Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Principal	800,000,000		$ 800,000,000	$ 100,000,000	$ 700,000,000
Unamortized debt discount	(158,077,000)		(184,698,000)
Unamortized issuance costs	(10,862,000)		(12,691,000)	(19,800,000)
Debt discount for conversion option	212,000,000		212,000,000
Issuance costs	(5,253,000)		(5,253,000)
Net carrying amount (equity)	206,747,000		206,747,000	212,000,000
0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Principal	173,018,000		345,000,000			$ 345,000,000
Unamortized debt discount	(16,484,000)		(42,280,000)
Unamortized issuance costs	(1,960,000)		(5,028,000)			(9,400,000)
Net carrying amount (liability)		156,100,000
Debt discount for conversion option	32,193,000		64,193,000
Issuance costs	(877,000)		(1,749,000)
Net carrying amount (equity)	31,316,000	345,600,000	62,444,000			64,200,000
Carrying Amount | 0% Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Net carrying amount (liability)		$ 758,700,000
Carrying Amount | 0.125% Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Net carrying amount (liability)				$ 588,000,000
Carrying Amount | 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Net carrying amount (liability)						$ 280,800,000
Carrying Amount | Fair Value, Measurements, Nonrecurring
Debt Instrument [Line Items]
Net carrying amount (liability)	1,536,984,000		900,303,000
Carrying Amount | Fair Value, Measurements, Nonrecurring | 0% Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Net carrying amount (liability)	751,349,000		0
Carrying Amount | Fair Value, Measurements, Nonrecurring | 0.125% Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Net carrying amount (liability)	631,061,000		602,611,000
Carrying Amount | Fair Value, Measurements, Nonrecurring | 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Net carrying amount (liability)	$ 154,574,000		$ 297,692,000

Convertible Senior Notes - Inte

Convertible Senior Notes - Interest Expense Recognized (Details) - Senior Notes - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
0% Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Contractual interest expense	$ 0		$ 0
Amortization of debt discount	4,491		4,491
Amortization of issuance costs	225		225
Total interest expense	4,716		4,716
0.125% Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Contractual interest expense	252	$ 252	750	$ 517
Amortization of debt discount	8,938	8,939	26,621	18,363
Amortization of issuance costs	614	614	1,829	1,262
Total interest expense	9,804	9,805	29,200	20,142
0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Contractual interest expense	169	217	599	645
Amortization of debt discount	2,458	3,161	8,709	9,377
Amortization of issuance costs	292	375	1,035	1,112
Total interest expense	$ 2,919	$ 3,753	$ 10,343	$ 11,134

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	Aug. 12, 2020numberOfPlaintiffs	Jul. 01, 2020numberOfPlaintiffs	May 12, 2020USD ($)numberOfPlaintiffs	Mar. 03, 2020USD ($)
Ingram Hosting Holdings LLC vs. Chegg | Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, damages sought, value | $				$ 17,000
2018 Data Incident, Arbitration Demands
Loss Contingencies [Line Items]
Loss contingency, number of arbitration demands filed | numberOfPlaintiffs	577
2018 Data Incident, Arbitration Demands | Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, number of arbitration demands filed | numberOfPlaintiffs		1,007	15,107
Loss contingency, damages sought, value | $			$ 25

Stockholders' Equity - Share-ba

Stockholders' Equity - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 21,529	$ 16,865	$ 59,409	$ 47,355
Cost of revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	262	96	644	295
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	8,433	5,741	23,044	15,876
Sales and marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	2,431	1,843	7,053	5,405
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 10,403	$ 9,185	$ 28,668	$ 25,779

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Details) - RSUs and PSUs	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Shares Outstanding
Number of RSUs and PSUs Outstanding, Beginning (shares) | shares	6,909,530
Number of RSUs and PSUs, Granted (shares) | shares	2,462,160
Number of RSUs and PSUs, Released (shares) | shares	(3,591,076)
Number of RSUs and PSUs, Canceled (shares) | shares	(409,544)
Number of RSUs and PSUs Outstanding, Ending (shares) | shares	5,371,070
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Beginning balance (in dollars per share) | $ / shares	$ 24.04
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	43.54
Weighted Average Grant Date Fair Value, Released (in dollars per share) | $ / shares	18.89
Weighted Average Grant Date Fair Value, Canceled (in dollars per share) | $ / shares	30.57
Weighted Average Grant Date Fair Value, Ending balance (in dollars per share) | $ / shares	$ 35.92

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details)	9 Months Ended
	Sep. 30, 2020USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Repurchase Program, Authorized Amount	$ 500,000,000
RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to restricted stock units	$ 122,800,000
Weighted average vesting period for recognition of compensation expense	2 years

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 1,066	$ 623	$ 2,875	$ 1,832

Related-Party Transactions (Det

Related-Party Transactions (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)board_member	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Adobe Systems | Chief Executive Officer
Related Party Transaction [Line Items]
Purchases from related party	$ 300,000	$ 400,000	$ 1,100,000	$ 1,900,000
Revenue from related parties	0	0	100,000	0
Due to related parties	100,000		100,000		$ 200,000
Receivables from related party	0		0
PayPal | Board Of Directors Member
Related Party Transaction [Line Items]
Expenses from transactions with related party	500,000	400,000	1,500,000	1,200,000
Synack, Inc. | Board Of Directors Member
Related Party Transaction [Line Items]
Purchases from related party	$ 0	$ 100,000	$ 100,000	$ 400,000
Number of board members appointed to board of directors of related party | board_member			1

Uncategorized Items - chgg-2020

Label	Element	Value
Restricted Cash and Cash Equivalents, Noncurrent	us-gaap_RestrictedCashAndCashEquivalentsNoncurrent	$ 1,181,000
Restricted Cash and Cash Equivalents, Noncurrent	us-gaap_RestrictedCashAndCashEquivalentsNoncurrent	1,736,000
Restricted Cash and Cash Equivalents, Current	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue	125,000
Restricted Cash and Cash Equivalents, Current	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue	$ 313,000