Chegg (CHGG) 10-Q 1 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 25, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
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 Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		144,947,411
Entity Central Index Key	0001364954
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 713,837	$ 479,853
Short-term investments	1,038,345	665,567
Accounts receivable, net of allowance of $111 and $153 at September 30, 2021 and December 31, 2020, respectively	9,302	12,913
Prepaid expenses	35,164	12,776
Other current assets	29,316	11,846
Total current assets	1,825,964	1,182,955
Long-term investments	813,500	523,628
Textbook library, net	15,834	34,149
Property and equipment, net	156,121	125,807
Goodwill	290,499	285,214
Intangible assets, net	43,573	51,249
Right of use assets	19,520	24,226
Other assets	22,484	24,030
Total assets	3,187,495	2,251,258
Current liabilities
Accounts payable	10,518	8,547
Deferred revenue	49,983	32,620
Accrued liabilities	73,320	68,565
Total current liabilities	133,821	109,732
Long-term liabilities
Convertible senior notes, net	1,676,749	1,506,922
Long-term operating lease liabilities	14,137	19,264
Other long-term liabilities	8,271	5,705
Total long-term liabilities	1,699,157	1,531,891
Total liabilities	1,832,978	1,641,623
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value per share, 10,000,000 shares authorized, no shares issued and outstanding	0	0
Common stock, $0.001 par value per share: 400,000,000 shares authorized; 144,901,435 and 129,343,524 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	145	129
Additional paid-in capital	1,717,421	1,030,577
Accumulated other comprehensive (loss) income	(1,552)	1,530
Accumulated deficit	(361,497)	(422,601)
Total stockholders' equity	1,354,517	609,635
Total liabilities and stockholders' equity	$ 3,187,495	$ 2,251,258

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 111	$ 153
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)	144,901,435	129,343,524
Common stock, shares outstanding (in shares)	144,901,435	129,343,524

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Net revenues	$ 171,942	$ 154,018	$ 568,798	$ 438,617
Cost of revenues	67,102	62,370	199,194	148,284
Gross profit	104,840	91,648	369,604	290,333
Operating expenses:
Research and development	43,269	44,041	130,995	123,956
Sales and marketing	27,239	24,625	75,139	60,621
General and administrative	33,971	40,784	111,560	98,221
Total operating expenses	104,479	109,450	317,694	282,798
Income (loss) from operations	361	(17,802)	51,910	7,535
Interest expense, net and other income (expense), net:
Interest expense, net	(1,633)	(17,468)	(5,263)	(44,320)
Other income (expense), net	8,670	(804)	(66,618)	7,396
Total interest expense, net and other income (expense), net	7,037	(18,272)	(71,881)	(36,924)
Income (loss) before provision for income taxes	7,398	(36,074)	(19,971)	(29,389)
Provision for income taxes	747	1,066	5,793	2,875
Net income (loss)	$ 6,651	$ (37,140)	$ (25,764)	$ (32,264)
Earnings Per Share [Abstract]
Basic (in dollars per share)	$ 0.05	$ (0.29)	$ (0.18)	$ (0.26)
Diluted (in dollars per share)	$ 0.05	$ (0.29)	$ (0.18)	$ (0.26)
Weighted average shares used to compute net income (loss) per share
Basic (in shares)	144,746	126,194	140,775	124,162
Diluted (in shares)	146,699	126,194	140,775	124,162

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 6,651	$ (37,140)	$ (25,764)	$ (32,264)
Other comprehensive (loss) income
Change in net unrealized (loss) gain on investments, net of tax	(455)	(1,642)	(1,974)	1,922
Change in foreign currency translation adjustments, net of tax	(127)	1,125	(1,108)	507
Other comprehensive (loss) income	(582)	(517)	(3,082)	2,429
Total comprehensive income (loss)	$ 6,069	$ (37,657)	$ (28,846)	$ (29,835)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Additional Paid-In CapitalCumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit	Accumulated DeficitCumulative Effect, Period of Adoption, Adjustment
Beginning balance (in shares) at Dec. 31, 2019			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]
Equity component on conversions	237,462			237,462
Purchase of 2026 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
Net proceeds from capped call related to conversions	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 share settlement of equity awards (in shares)			2,110,000
Net share 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 income (loss)	(32,264)						(32,264)
Ending balance (in shares) at Sep. 30, 2020			128,654,000
Beginning balance at Sep. 30, 2020	645,392		$ 129	1,092,574		1,333	(448,644)
Beginning balance (in shares) at Dec. 31, 2019			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	Accounting Standards Update 2020-06
Ending balance (in shares) at Dec. 31, 2020	129,343,524		129,344,000
Beginning balance at Dec. 31, 2020	$ 609,635	(378,138)	$ 129	1,030,577	$ (465,006)	1,530	(422,601)	86,868
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 on conversions	237,462			237,462
Purchase of 2026 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
Net proceeds from capped call related to conversions	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 share settlement of equity awards (in shares)			243,000
Net share settlement of equity awards	(11,120)			(11,120)
Share-based compensation expense	21,529			21,529
Other comprehensive income (loss)	(517)					(517)
Net income (loss)	(37,140)						(37,140)
Ending balance (in shares) at Sep. 30, 2020			128,654,000
Beginning balance at Sep. 30, 2020	$ 645,392		$ 129	1,092,574		1,333	(448,644)
Beginning balance (in shares) at Dec. 31, 2020	129,343,524		129,344,000
Beginning balance at Dec. 31, 2020	$ 609,635	$ (378,138)	$ 129	1,030,577	$ (465,006)	1,530	(422,601)	$ 86,868
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with equity offering, net of offering costs (in shares)			10,975,000
Issuance of common stock in connection with equity offering, net of offering costs	1,091,466		$ 11	1,091,455
Equity component on conversions	(236,920)			(236,920)
Issuance of common stock upon conversion of 2023 convertible senior notes (in shares)			2,983,000
Issuance of common stock upon conversion of 2023 convertible senior notes	235,521		$ 3	235,518
Net proceeds from capped call related to conversions	67,769			67,769
Issuance of common stock upon exercise of stock options and ESPP (in shares)			178,000
Issuance of common stock upon exercise of stock options and ESPP	5,371			5,371
Net share settlement of equity awards (in shares)			1,421,000
Net share settlement of equity awards	(89,337)		$ 2	(89,339)
Share-based compensation expense	77,996			77,996
Other comprehensive income (loss)	(3,082)					(3,082)
Net income (loss)	$ (25,764)						(25,764)
Ending balance (in shares) at Sep. 30, 2021	144,901,435		144,901,000
Beginning balance at Sep. 30, 2021	$ 1,354,517		$ 145	1,717,421		(1,552)	(361,497)
Beginning balance (in shares) at Jun. 30, 2021			144,621,000
Beginning balance at Jun. 30, 2021	1,337,882		$ 145	1,706,855		(970)	(368,148)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and ESPP (in shares)			14,000
Issuance of common stock upon exercise of stock options and ESPP	106			106
Net share settlement of equity awards (in shares)			266,000
Net share settlement of equity awards	(14,697)			(14,697)
Share-based compensation expense	25,157			25,157
Other comprehensive income (loss)	(582)					(582)
Net income (loss)	$ 6,651						6,651
Ending balance (in shares) at Sep. 30, 2021	144,901,435		144,901,000
Beginning balance at Sep. 30, 2021	$ 1,354,517		$ 145	$ 1,717,421		$ (1,552)	$ (361,497)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Operating activities
Net loss	$ 6,651	$ (37,140)	$ (25,764)	$ (32,264)
Adjustments to reconcile net loss to net cash provided by operating activities:
Print textbook depreciation expense			9,024	10,699
Other depreciation and amortization expense			46,273	33,088
Share-based compensation expense			76,157	59,409
Amortization of debt discount and issuance costs			4,509	42,910
Repayment of convertible senior notes attributable to debt discount			0	(14,912)
Loss on early extinguishment of debt	0	3,315	78,152	3,315
Loss on change in fair value of derivative instruments, net	0	0	7,148	0
Loss from write-off of property and equipment			1,857	1,057
Loss from impairment of strategic equity investment			0	10,000
Gain on sale of strategic equity investments	(7,158)	0	(12,496)	0
Loss (gain) on textbook library, net			8,765	(2,028)
Operating lease expense, net of accretion			4,527	3,400
Restructuring charges			1,851	0
Other non-cash items			498	(102)
Change in assets and liabilities, net of effect of acquisition of businesses:
Accounts receivable			3,593	106
Prepaid expenses and other current assets			(31,070)	(6,178)
Other assets			9,472	(2,638)
Accounts payable			1,820	(1,634)
Deferred revenue			17,363	32,239
Accrued liabilities			10,552	34,276
Other liabilities			(4,108)	(2,088)
Net cash provided by operating activities			208,123	168,655
Investing activities
Purchases of property and equipment			(67,126)	(57,457)
Purchases of textbooks			(10,666)	(49,641)
Proceeds from disposition of textbooks			7,815	7,012
Purchases of investments			(1,574,060)	(968,106)
Maturities of investments			893,315	412,046
Purchase of strategic equity investment			0	(2,000)
Proceeds from sale of strategic equity investments			16,076	0
Acquisition of businesses, net of cash acquired			(7,891)	(92,796)
Net cash used in investing activities			(742,537)	(750,942)
Financing activities
Proceeds from common stock issued under stock plans, net			5,373	9,236
Payment of taxes related to the net share settlement of equity awards			(89,339)	(65,224)
Proceeds from issuance of convertible senior notes, net of issuance costs			0	984,096
Purchase of convertible senior notes capped call			0	(103,400)
Proceeds from equity offering, net of offering costs			1,091,466	0
Repayment of convertible senior notes			(300,755)	(159,677)
Proceeds from exercise of convertible senior notes capped call			69,005	57,414
Payment of escrow related to acquisition			(7,451)	0
Net cash provided by financing activities			768,299	722,445
Net increase in cash, cash equivalents and restricted cash			233,885	140,158
Cash, cash equivalents and restricted cash, beginning of period			481,715	389,432	$ 389,432
Cash, cash equivalents and restricted cash, end of period	715,600	529,590	715,600	529,590	481,715
Supplemental cash flow data:
Interest			1,053	1,546
Income taxes, net of refunds			5,610	2,450
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases			5,934	5,174
Right of use assets obtained in exchange for lease obligations, operating lease			0	1,713
Non-cash investing and financing activities:
Accrued purchases of long-lived assets			1,837	6,102
Accrued escrow related to acquisition			0	7,451
Issuance of common stock related to repayment of convertible senior notes			235,521	327,141
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	713,837	527,541	713,837	527,541	479,853
Restricted cash included in other current assets	0	313	0	313
Restricted cash included in other assets	1,763	1,736	1,763	1,736
Total cash, cash equivalents and restricted cash	$ 715,600	$ 529,590	$ 715,600	$ 529,590	$ 481,715

Background and Basis of Present

Background and Basis of Presentation	9 Months Ended
	Sep. 30, 2021
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. Millions of people Learn with Chegg. We strive to improve educational outcomes by putting the student first. We support students on their journey from high school to college and into their career with tools designed to help them learn their course materials, succeed in their classes, save money on required materials, and learn the most in-demand skills. Our services are available online, anytime and anywhere. Basis of Presentation The accompanying condensed consolidated balance sheet as of September 30, 2021, the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive income (loss), and the condensed consolidated statements of stockholders' equity for the three and nine months ended September 30, 2021 and 2020, the condensed consolidated statements of cash flows for the nine months ended September 30, 2021 and 2020, 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, 2021, our results of operations, results of comprehensive income (loss), and stockholders' equity for the three and nine months ended September 30, 2021 and 2020, and cash flows for the nine months ended September 30, 2021 and 2020. Our results of operations, results of comprehensive income (loss), stockholders' equity, and cash flows for the nine months ended September 30, 2021 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, 2020 as 2020. 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, 2020 (the Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). Except for our policies on convertible senior notes, net, share-based compensation expense, and net income (loss) per share, 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. Our policies on convertible senior notes, net and net income (loss) per share were updated as a result of our adoption of Accounting Standards Update (ASU) 2020-06, Accounting for Convertible Instruments and Contracts in an Entity's Own Equity on January 1, 2021 under the modified retrospective method. For further information on ASU 2020-06, see the section below titled “Recent Accounting Pronouncements” of this Note 1, “Background and Basis of Presentation.” 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.” The notes, including the embedded conversion features, are accounted for under the traditional convertible debt accounting model entirely as a liability net of unamortized issuance costs. The carrying amount of the liability is classified as a current liability if we have committed to settle with current assets; otherwise, we classify it as a long-term liability as we retain the election to settle conversion requests in shares of our common stock. The embedded conversion features are not remeasured as long as they do not meet the separation requirement of a derivative; otherwise, they are classified as derivative instruments and recorded at fair value with changes in fair value recorded in other income (expense), net on our condensed consolidated statements of operations. The fair value of any derivative instruments related to the notes are determined utilizing Level 2 inputs. Issuance costs are amortized on a straight-line basis, which approximates the effective interest rate method, to interest expense over the term of the notes. In accounting for conversions of the notes, the carrying amount of the converted notes is reduced by the total consideration paid or issued for the respective converted notes and the difference is recorded to additional paid-in capital on our condensed consolidated balance sheets. In accounting for extinguishments of the notes, the reacquisition price of the extinguished notes is compared to the carrying amount of the respective extinguished notes and a gain or loss is recorded in other income (expense), net on our condensed consolidated statements of operations. Share-based Compensation Expense Share-based compensation expense for restricted stock units (RSUs), performance-based restricted stock units (PSUs) with either a market-based condition or financial performance targets, and the employee stock purchase plan (ESPP) is accounted for under the fair value method based on the grant-date fair value of the award. Share-based compensation expense for RSUs and PSUs with financial performance targets is measured based on the closing fair market value of the Company’s common stock, PSUs with a market-based condition is estimated using a Monte Carlo simulation model, and the ESPP is estimated using the Black-Scholes-Merton option pricing model. We recognize share-based compensation expense, subject to continuing service over the requisite service period, which is generally the vesting period, on a straight-line basis for RSUs and the ESPP and on a graded basis for PSUs. Share-based compensation expense for PSUs with a market-based condition is recognized regardless of whether the market condition is satisfied whereas share-based compensation expense for PSUs with financial performance targets is recognized upon estimated or actual achievement of such targets. These amounts are reduced by estimated forfeitures, which are estimated at the time of the grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Net Income (Loss) Per Share Basic net income (loss) per share is computed by dividing net income (loss) by the weighted-average number of shares of common stock outstanding during the period. Diluted net income (loss) per share is computed by adjusting net income (loss) for all related interest expense and gains and losses recognized during the period, net of tax, and giving effect to all potential shares of common stock, including stock options, PSUs, RSUs, and shares related to convertible senior notes, to the extent dilutive. This assumes that all stock options and dilutive convertible shares were exercised or converted and is computed by applying the treasury stock method for outstanding stock options, PSUs, and RSUs, and the if-converted method for outstanding convertible senior notes. Under the treasury stock method, options, PSUs, and RSUs are assumed to be exercised or vested at the beginning of the period (or at the time of issuance, if later) and as if funds obtained thereby were used to purchase common stock at the average market price during the period. Under the if-converted method, outstanding convertible senior notes are assumed to be converted into common stock at the beginning of the period (or at the time of issuance, if later). 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. 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. Except for estimates related to the grant-date fair value of PSUs with a market-based condition, there have been no material changes in our use of estimates during the nine months ended September 30, 2021 as compared to the use of estimates disclosed in Part II, Item 8 “Consolidated Financial Statements and Supplementary Data” contained in our Annual Report on Form 10-K for the year ended December 31, 2020. Reclassification of Prior Period Presentation In order to conform with current period presentation, $6.6 million of current operating lease liabilities have been reclassified to accrued liabilities on our condensed consolidated balance sheet as of December 31, 2020. This change in presentation does not affect previously reported results. Condensed Consolidated Statements of Operations Details Other income (expense), net consists of the following (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Loss on early extinguishment of debt (1) $ — $ (3,315) $ (78,152) $ (3,315) Loss on change in fair value of derivative instruments, net (1) — — (7,148) — Gain on sale of strategic equity investments (2) 7,158 — 12,496 — Interest income 1,485 2,539 5,385 10,588 Other 27 (28) 801 123 Total other income (expense), net $ 8,670 $ (804) $ (66,618) $ 7,396 (1) For further information, see Note 7, “Convertible Senior Notes.” (2) For further information, see Note 4, “Cash and Cash Equivalents, and Investments.” Recent Accounting Pronouncements Recently Issued Accounting Pronouncements Not Yet Adopted In May 2021, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2021-04, Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options . ASU 2021-04 aims to clarify and reduce diversity in an issuer’s accounting for modifications or exchanges of freestanding equity-classified written call options that remain equity classified after modification or exchange based on the economic substance of the modification or exchange. Early adoption is permitted and the guidance must be applied prospectively to all modifications or exchanges that occur on or after the date of adoption. The guidance is effective for annual periods beginning after December 15, 2021, and we are currently in the process of evaluating the impact of this guidance. Recently Adopted Accounting Pronouncements In August 2020, the FASB issued 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 . Under ASU 2020-06, convertible instruments with embedded conversion features, that are not required to be accounted for as a derivative or that do not result in a substantial premium, are no longer required to be separated from the host contract thereby eliminating the cash conversion feature model. Instead, these convertible debt instruments will be accounted for as a single liability measured at amortized cost under the traditional convertible debt accounting model. ASU 2020-06 also requires the if-converted method to be applied for all convertible instruments when calculating diluted earnings per share. We adopted ASU 2020-06 on January 1, 2021 under the modified retrospective method applied to convertible senior notes outstanding as of January 1, 2021 and have not changed previously disclosed amounts or provided additional disclosures for comparative periods. Adoption of ASU 2020-06 resulted in an increase to convertible senior notes of $378.1 million and a decrease to additional paid-in capital of $465.0 million due to the application of the traditional convertible debt model and no longer separating the embedded conversion feature. Accumulated deficit also decreased by $86.9 million due to the reduction in non-cash interest expense related to the debt discount and we expect interest expense to decrease in future periods. Refer to Note 7, “Convertible Senior Notes” for more information.

Revenues

Revenues	9 Months Ended
	Sep. 30, 2021
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 being recognized at a point in time. 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 Change 2021 2020 $ % Chegg Services $ 146,790 $ 118,895 $ 27,895 23 % Required Materials 25,152 35,123 (9,971) (28) Total net revenues $ 171,942 $ 154,018 $ 17,924 12 Nine Months Ended Change 2021 2020 $ % Chegg Services $ 482,654 $ 345,258 $ 137,396 40 % Required Materials 86,144 93,359 (7,215) (8) Total net revenues $ 568,798 $ 438,617 $ 130,181 30 During the three and nine months ended September 30, 2021, we recognized $31.3 million and $32.6 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 $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, 2021, we recognized a reduction of revenues of an immaterial amount and $3.4 million, respectively, from performance obligations satisfied in previous periods primarily due to a change in the estimated variable consideration ascribed to Thinkful. 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, 2021, we recognized $6.2 million and $26.9 million, respectively, of operating lease income from print textbook rentals that we own. 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. Contract Balances The following table presents our accounts receivable, net, deferred revenue, and contract assets balances (in thousands, except percentages): Change September 30, December 31, 2020 $ % Accounts receivable, net $ 9,302 $ 12,913 $ (3,611) (28) % Deferred revenue 49,983 32,620 17,363 53 Contract assets 16,358 13,243 3,115 24 During the nine months ended September 30, 2021, our accounts receivable, net balance decreased by $3.6 million, or 28%, primarily due to timing of billings and seasonality of our business. During the nine months ended September 30, 2021, our deferred revenue balance increased by $17.4 million, or 53%, primarily due to increased bookings and seasonality of our business. During the nine months ended September 30, 2021, our contract assets balance increased by $3.1 million, or 24%, primarily due to our Thinkful service.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	Net Income (Loss) Per Share Adoption of ASU 2020-06, Accounting for Convertible Instruments and Contracts in an Entity's Own Equity We adopted ASU 2020-06 on January 1, 2021 under the modified retrospective method applied to convertible senior notes outstanding as of January 1, 2021 and have not changed previously disclosed amounts or provided additional disclosures for comparative periods. ASU 2020-06 requires the if-converted method to be applied for all convertible instruments when calculating diluted earnings per share. Under the if-converted method, outstanding convertible senior notes are assumed to be converted into common stock at the beginning of the period (or at the time of issuance, if later). The following table sets forth the computation of basic and diluted net income (loss) per share (in thousands, except per share amounts): Three Months Ended Nine Months Ended 2021 2020 (1) 2021 2020 (1) Basic Numerator: Net income (loss) $ 6,651 $ (37,140) $ (25,764) $ (32,264) Denominator: Weighted average shares used to compute net income (loss) per share, basic 144,746 126,194 140,775 124,162 Net income (loss) per share, basic $ 0.05 $ (0.29) $ (0.18) $ (0.26) Diluted Numerator: Net income (loss), diluted $ 6,651 $ (37,140) $ (25,764) $ (32,264) Denominator: Weighted average shares used to compute net income (loss) per share, basic 144,746 126,194 140,775 124,162 Options to purchase common stock 485 — — — PSUs and RSUs 1,462 — — — Employee stock purchase plan 6 — — — Weighted average shares used to compute net income (loss) per share, diluted 146,699 126,194 140,775 124,162 Net income (loss) per share, diluted $ 0.05 $ (0.29) $ (0.18) $ (0.26) (1) As noted above, prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method. The following potential weighted-average shares of common stock outstanding were excluded from the computation of diluted net income (loss) per share because including them would have been anti-dilutive (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Options to purchase common stock — 865 515 977 PSUs and RSUs 849 3,394 2,210 3,425 Shares related to convertible senior notes 22,875 8,721 23,876 4,422 Employee stock purchase plan — 9 2 4 Total common stock equivalents 23,724 12,989 26,603 8,828

Cash and Cash Equivalents, and

Cash and Cash Equivalents, and Investments	9 Months Ended
	Sep. 30, 2021
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, 2021 and December 31, 2020 (in thousands): September 30, 2021 Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 29,338 $ — $ — $ 29,338 Money market funds 684,499 — — 684,499 Total cash and cash equivalents $ 713,837 $ — $ — $ 713,837 Short-term investments: Commercial paper $ 364,098 $ 49 $ (4) $ 364,143 Corporate debt securities 658,525 280 (122) 658,683 Agency bonds 15,501 18 — 15,519 Total short-term investments $ 1,038,124 $ 347 $ (126) $ 1,038,345 Long-term investments: Corporate debt securities $ 813,889 $ 142 $ (531) $ 813,500 Total long-term investments $ 813,889 $ 142 $ (531) $ 813,500 December 31, 2020 Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 15,054 $ — $ — $ 15,054 Money market funds 464,799 — — 464,799 Total cash and cash equivalents $ 479,853 $ — $ — $ 479,853 Short-term investments: Commercial paper $ 204,152 $ 24 $ (6) $ 204,170 Corporate debt securities 459,967 1,478 (48) 461,397 Total short-term investments $ 664,119 $ 1,502 $ (54) $ 665,567 Long-term investments: Corporate debt securities $ 484,275 $ 605 $ (283) $ 484,597 Agency bonds 38,995 36 — 39,031 Total long-term investments $ 523,270 $ 641 $ (283) $ 523,628 The following table shows our cash equivalents and investments' adjusted cost and fair value by contractual maturity as of September 30, 2021 (in thousands): Adjusted Cost Fair Value Due in 1 year or less $ 1,038,124 $ 1,038,345 Due in 1-2 years 813,889 813,500 Investments not due at a single maturity date 684,499 684,499 Total $ 2,536,512 $ 2,536,344 Investments not due at a single maturity date in the preceding table consisted of money market funds. As of September 30, 2021, we determined that the declines in the market value of our investment portfolio were not 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- and a weighted average maturity of less than twelve months. In addition, our investment policy limits the amount of our credit exposure to any one issuer or industry sector. The policy requires investments 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, 2021 and 2020, we did not recognize any losses on our investments due to credit related factors. Strategic Investments We previously invested $2.0 million in TAPD, Inc., also known as Frank; a U.S.-based service that helps students access financial aid. In September 2021, we sold our investment in Frank for total consideration of $9.2 million, resulting in a $7.2 million gain included within other income (expense), net on our condensed consolidated statements of operations. We received a cash payment of $9.0 million included within cash flows from investing activities on our condensed consolidated statements of cash flows. We also previously invested $3.0 million in a foreign entity to explore expanding our reach internationally. In March 2021, we sold our investment in that foreign entity for total consideration of $8.3 million, resulting in a $5.3 million gain included within other income (expense), net on our condensed consolidated statements of operations. We received a cash payment, net of taxes withheld, of $7.1 million included within cash flows from investing activities on our condensed consolidated statements of cash flows. Aside from a $10.0 million impairment charge previously recorded in 2020 on our strategic investment in WayUp, Inc., we did not record any other impairment charges on our strategic investments during the three and nine months ended September 30, 2021 and 2020, 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, 2021 and 2020. As of September 30, 2021, we had no amounts related to strategic investments on our condensed consolidated balance sheet.

Fair Value Measurement

Fair Value Measurement	9 Months Ended
	Sep. 30, 2021
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, 2021 and December 31, 2020 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2021 Total Level 1 Level 2 Assets: Cash equivalents: Money market funds $ 684,499 $ 684,499 $ — Short-term investments: Commercial paper 364,143 — 364,143 Corporate debt securities 658,683 — 658,683 Agency bonds 15,519 — 15,519 Long-term investments: Corporate debt securities 813,500 — 813,500 Total assets measured and recorded at fair value $ 2,536,344 $ 684,499 $ 1,851,845 December 31, 2020 Total Level 1 Level 2 Assets: Cash equivalents: Money market funds $ 464,799 $ 464,799 $ — Short-term investments: Commercial paper 204,170 — 204,170 Corporate debt securities 461,397 — 461,397 Long-term investments: Corporate debt securities 484,597 — 484,597 Agency bonds 39,031 — 39,031 Total assets measured and recorded at fair value $ 1,653,994 $ 464,799 $ 1,189,195 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, 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 investments 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, refer to Note 7, “Convertible Senior Notes.” The carrying amounts and estimated fair values of the notes as of September 30, 2021 and December 31, 2020 are as follows (in thousands): September 30, 2021 December 31, 2020 (1) Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value 2026 notes $ 987,027 $ 984,880 $ 761,930 $ 1,129,370 2025 notes 689,722 1,011,050 640,614 1,456,800 2023 notes — — 104,378 376,949 Convertible senior notes, net $ 1,676,749 $ 1,995,930 $ 1,506,922 $ 2,963,119 (1) Prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method. Refer to Note 7, “Convertible Senior Notes” for more information.

Acquisition

Acquisition	9 Months Ended
	Sep. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Acquisition	AcquisitionOn February 22, 2021, we completed an acquisition, accounted for as a business combination, of 100% of the outstanding shares of a company for a technology that will strengthen our content creation abilities for a purchase consideration of $8.0 million in cash. Our preliminary total allocation of purchase consideration included acquired assets of $0.4 million, acquired developed technology intangible asset of $3.3 million and goodwill of $5.8 million less assumed liabilities of $1.5 million. This acquisition did not have a material impact on our condensed consolidated financial statements and is not expected to have a material impact in future periods.

Convertible Senior Notes

Convertible Senior Notes	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Convertible Senior Notes	Convertible Senior Notes Adoption of ASU 2020-06, Accounting for Convertible Instruments and Contracts in an Entity's Own Equity We adopted ASU 2020-06 on January 1, 2021 under the modified retrospective method applied to convertible senior notes outstanding as of January 1, 2021 and have not changed previously disclosed amounts or provided additional disclosures for comparative periods. Under ASU 2020-06, convertible instruments with embedded conversion features, that are not required to be accounted for as a derivative or that do not result in a substantial premium, are no longer required to be separated from the host contract thereby eliminating the cash conversion feature model. Instead, these convertible debt instruments will be accounted for as a single liability measured at amortized cost under the traditional convertible debt accounting model. In 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 and together with the 2026 notes and the 2025 notes, the notes). The aggregate principal amount of the 2023 notes included $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. 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 During the nine months ended September 30, 2021, we settled $115.6 million of aggregate principal amount of the 2023 notes, consisting of $24.7 million related to requests for conversions and $90.9 million pursuant to our election of our option to redeem the remaining outstanding 2023 notes, for a total aggregate consideration of $351.1 million, consisting of $115.6 million in cash and 2,983,011 shares of our common stock with a value of $235.5 million. The carrying amount of the 2023 notes was $114.2 million, resulting in a $236.9 million difference that was recorded in additional paid-in capital on our condensed consolidated balance sheet. Additionally, we entered into 2023 notes capped call privately-negotiated transactions which terminated capped call transactions underlying 4,288,459 shares of our common stock and received aggregate cash proceeds of $45.2 million. As of September 30, 2021, no amounts of our 2023 notes remain outstanding and no shares remain underlying the 2023 notes capped call transactions. In March 2021, in connection with our securities repurchase program, we extinguished $100.0 million aggregate principal amount of the 2025 notes in privately-negotiated transactions for aggregate consideration of $184.9 million, which was paid in cash. Upon execution, we concluded that the 2025 notes embedded conversion features no longer met the derivative scope exception and, as a result, initially recorded a derivative liability of $176.5 million, related to the fair value of extinguished 2025 notes. We settled the derivative liability for aggregate consideration of $184.9 million resulting in a $8.4 million loss on change in fair value. The carrying amount of the 2025 notes subject to the extinguishment was $98.3 million resulting in a $78.2 million loss on early extinguishment of debt. Additionally, we entered into 2025 notes capped call privately-negotiated transactions which terminated capped call transactions underlying 1,939,560 shares of our common stock and received aggregate cash proceeds of $23.9 million. Upon execution, we concluded that the capped call transactions no longer met the derivative scope exception and, as a result recorded a derivative liability of $22.6 million related to the fair value of terminated 2025 notes capped call transactions. We settled the capped call transactions for aggregate consideration of $23.9 million resulting in a $1.3 million gain on change in fair value. 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 bore interest of 0.25% per year which was payable semi-annually in arrears on May 15 and November 15 of each year, beginning on November 15, 2018. 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 was initially convertible into 37.1051 shares of our common stock. This was equivalent to an initial conversion price of approximately $26.95 per share, which was 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 and December 15, 2024 for the 2025 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 and June 30, 2019 for the 2025 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 and December 15, 2024 for the 2025 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 noted above allowing holders of the 2025 notes to convert was met during the three months ended September 30, 2021, June 30, 2021, March 31, 2021, December 31, 2020 and September 30, 2020 and therefore, the 2025 notes were and are convertible starting October 1, 2020 through December 31, 2021. Aside from the extinguishment of $100.0 million aggregate principal amount of the 2025 notes discussed above, during the three and nine months ended September 30, 2021, we received immaterial requests for conversion of the 2025 notes which we settled or intend to settle in cash. During the year ended December 31, 2020, 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. The net carrying amount of the notes is as follows (in thousands): September 30, 2021 December 31, 2020 (1) 2026 Notes 2025 Notes 2026 Notes 2025 Notes 2023 Notes Principal $ 1,000,000 $ 699,989 $ 1,000,000 $ 800,000 $ 115,576 Unamortized debt discount — — (226,732) (149,138) (9,953) Unamortized issuance costs (12,973) (10,267) (11,338) (10,248) (1,245) Net carrying amount $ 987,027 $ 689,722 $ 761,930 $ 640,614 $ 104,378 (1) As noted above, prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method. The following tables set forth the total interest expense recognized related to the notes (in thousands): Three Months Ended September 30, 2021 2020 (1) 2026 Notes 2025 Notes 2026 Notes 2025 Notes 2023 Notes Contractual interest expense $ — $ 221 $ — $ 252 $ 169 Amortization of debt discount — — 4,491 8,938 2,458 Amortization of issuance costs 663 749 225 614 292 Total interest expense $ 663 $ 970 $ 4,716 $ 9,804 $ 2,919 (1) As noted above, prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method . Nine Months Ended September 30, 2021 2020 (1) 2026 Notes 2025 Notes 2023 Notes 2026 Notes 2025 Notes 2023 Notes Contractual interest expense $ — $ 676 $ 78 $ — $ 750 $ 599 Amortization of debt discount — — — 4,491 26,621 8,709 Amortization of issuance costs 1,970 2,297 242 225 1,829 1,035 Total interest expense $ 1,970 $ 2,973 $ 320 $ 4,716 $ 29,200 $ 10,343 (1) As noted above, prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method . Capped Call Transactions Concurrently with the offering of the 2026 notes and 2025 notes, we used $103.4 million and $97.2 million, respectively, of the net proceeds to enter into privately negotiated capped call transactions which are expected to reduce or offset potential dilution to holders of our common stock upon conversion of the notes 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 as of September 30, 2021, cover 9,297,800 and 13,576,706 shares of our common stock for the 2026 notes and 2025 notes, respectively. These are intended to effectively increase the overall conversion price from $107.55 to $156.44 per share for the 2026 notes and $51.56 to $79.32 per share for the 2025 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, 2021
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 September 13, 2021, Pearson Education, Inc. (Pearson) filed a complaint captioned Pearson Education, Inc. v. Chegg, Inc. (Pearson Complaint) in the United States District Court for the District of New Jersey against the Company (Case 2:21-cv-16866), alleging infringement of Pearson’s registered copyrights and exclusive rights under copyright in violation of the United States Copyright Act. Pearson is seeking injunctive relief, monetary damages, costs, and attorneys’ fees. The Company’s answer to the Pearson Complaint is due by November 19, 2021. The Company disputes these claims and intends to vigorously defend itself in this matter. On December 1, 2020, we received notice that a class action lawsuit was filed against Chegg in New York alleging violations of the American with Disabilities Act. The claim asserted that one of Chegg’s websites is not compatible with software used by vision-impaired individuals. During the nine months ended September 30, 2021, we settled this matter for an immaterial amount. On August 18, 2020, we received notice that a class action lawsuit was filed against Chegg in California alleging violations of the Unruh Civil Rights Act. The claim asserted that one of Chegg’s websites is not compatible with software used by vision-impaired individuals. During the nine months ended September 30, 2021, we settled this matter for an immaterial amount. On July 21, 2020, VitalSource Technologies LLC (VST), which is wholly owned by Ingram Industries Inc., filed a complaint against Chegg alleging that Chegg breached its contract with VST involving the development of an eTextbook reader and eTextbook reader platform. The suit sought uncertain damages, but the complaint alleged that they exceeded $75 thousand. During the nine months ended September 30, 2021, we settled this matter for an immaterial amount. 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. We have provided the FTC with the requested responses to interrogatories and follow-up questions and have produced documents pertaining to data breach incidents and our data security and privacy practices generally. On May 12, 2020, we received notice that 15,107 arbitration demands were filed against us by individuals all represented by the same legal counsel, each individual claimant alleging to have suffered more than $25 thousand in damages as a result of the unauthorized access of certain items of their user data in April 2018 (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; cases have been filed by the same counsel in Maryland and California. We dispute that these claimants have a valid basis for seeking arbitration, assert that they have acted in bad faith and are working with the Maryland and California courts and plaintiffs’ counsel on resolution of these claims. On August 22, 2021, Chegg and the claimaints' legal counsel, on behalf of its clients, entered into a settlement agreement (Settlement Agreement), pursuant to which each eligible claimant that signs a release agreement agrees, among other things, to dismiss with prejudice all claims against Chegg that such claimant currently maintains in exchange for such claimant's pro rata portion of the settlement amount. Claimants have until January 26, 2022 to sign their release agreements. In March 2021, we recorded a loss contingency accrual and a corresponding insurance loss recovery, the net impact of which did not materially impact our condensed consolidated statements of operations. On November 5, 2018, NetSoc, LLC (NetSoc) filed a complaint against us captioned NetSoc, LLC v. Chegg, Inc. , (Civil Action No. 1:18-CV-10262-RAC) in the U.S. District Court for the Southern District of New York (SDNY) for patent infringement alleging that the Chegg Tutors service infringes U.S. Patent No. 9,978,107 (the NetSoc Patent) and seeking unspecified compensatory damages. A responsive pleading was filed on February 19, 2019. On January 13, 2020, the SDNY issued an order dismissing the case as to Chegg. On January 30, 2020, NetSoc appealed the dismissal to the United States Court of Appeals for the Federal Circuit (the Federal Circuit). On September 24, 2021, the Federal Circuit dismissed NetSoc's appeal of the SDNY dismissal. On December 2, 2020, the U.S. Patent and Trademark Office determined that the NetSoc Patent is invalid based on two Inter Partes Review (IPR) proceedings instituted in part by Chegg, and on January 4, 2021, NetSoc filed a Notice of Appeals at the Federal Circuit appealing the IPR decisions. On October 18, 2021, Chegg filed a motion to dismiss NetSoc's appeal of the IPR decisions.

Guarantees and Indemnifications

Guarantees and Indemnifications	9 Months Ended
	Sep. 30, 2021
Guarantees And Indemnifications [Abstract]
Guarantees and Indemnifications	Guarantees and Indemnifications We have agreed to indemnify our directors and officers for certain events or occurrences, subject to certain limits, while such persons are or were serving at our request in such capacity. We may terminate the indemnification agreements with these persons upon termination of employment, but termination will not affect claims for indemnification related to events occurring prior to the effective date of termination. We have a directors’ and officers’ insurance policy that limits our potential exposure up to the limits of our insurance coverage. In addition, we also have other indemnification agreements with various vendors against certain claims, liabilities, losses, and damages. The maximum amount of potential future indemnification is unlimited. We believe the fair value of these indemnification agreements is immaterial. We have not recorded any liabilities for these agreements as of September 30, 2021.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Stockholders' Equity	Stockholders' Equity Equity Offering In February 2021, we entered into an underwriting agreement pursuant to which we agreed to issue and sell 10,974,600 shares of our common stock at a public offering price of $102.00 per share generating aggregate net proceeds of $1,091.5 million, after deducting underwriting discounts and commissions of $26.9 million and offering expenses of $1.1 million. Securities Repurchase Program In November 2021, our board of directors approved a $500.0 million increase to our existing securities repurchase program authorizing the repurchase of up to $1.0 billion 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. During the nine months ended September 30, 2021, we repurchased $100.0 million of aggregate principal amount of the 2025 notes in privately-negotiated transactions for an aggregate consideration of $184.9 million. $665.5 million remains under the repurchase program, which has no expiration date and will continue until otherwise suspended, terminated or modified at any time for any reason by our board of directors. Share-based Compensation Expense Total share-based compensation expense recorded for employees and non-employees is as follows (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Cost of revenues $ 393 $ 262 $ 1,174 $ 644 Research and development 8,917 8,433 25,976 23,044 Sales and marketing 3,051 2,431 9,625 7,053 General and administrative 12,151 10,403 39,382 28,668 Total share-based compensation expense $ 24,512 $ 21,529 $ 76,157 $ 59,409 During the three and nine months ended September 30, 2021, we capitalized share-based compensation expense of $0.6 million and $1.8 million, respectively. 2021 PSU Grants with Market-Based Conditions In March 2021, we granted PSUs under the 2013 Equity Incentive Plan (the 2013 Plan) with market-based conditions to certain of our key employees. The number of shares of our common stock that may be issued to settle these PSUs range from 50% at the threshold level to 150% at the maximum level of the 100% target level of the award depending on achieving a maximum average market value of the per share price of our common stock, for a period of 60 consecutive trading days, over a three-year performance period ending on the third anniversary of the date of grant. No payout will be made for performance below the 50% threshold level. The market value of the per share price of our common stock must reach $123.81, $148.58, or $173.34 at the threshold, target, or maximum levels, respectively, for achievement of the award, which could result in issuance of 244,086, 488,173, or 732,260 shares of our common stock at each respective payout level. These PSUs will vest over a four-year period, with the initial vesting of 50% of the award occurring in March 2024. The number of PSUs granted totaled 732,260 shares, which represents the maximum number of shares, and had a grant date fair value of $68.55 per share, determined under the Monte Carlo simulation approach described further below. As of September 30, 2021, the market-based conditions have not been met. Fair Value of PSUs with Market-Based Conditions PSUs with market-based conditions are converted into shares of our common stock upon vesting on a one-for-one basis. Vesting is subject to the achievement of certain per share price of our common stock targets and the employee's continuing service to us. If the targets are achieved, the awards vest over a four-year period. We estimate the fair value of the PSUs using a Monte Carlo simulation approach, which utilizes the fair value of our common stock based on an active market and requires input on the following subjective assumptions: Expected Term . The expected term for the awards is the performance period of three years. Expected Volatility . The expected volatility is based on the historical average volatility of our stock price over the expected term. Expected Dividends . The dividend assumption is based on our historical experience. To date we have not paid any dividends on our common stock. Risk-Free Interest Rate . The risk-free interest rate used in the valuation method is the implied yield currently available on the U.S. treasury zero-coupon issues, with a remaining term equal to the expected term. The following table summarizes the key assumptions used to determine the fair value of the awards: Expected term (years) 3.00 Expected volatility 49.04 % Expected dividends — % Risk-free interest rate 0.27 % 2021 PSU Grants with Financial and Strategic Performance Targets In March 2021, we granted PSUs under the 2013 Plan to certain of our key executives. These PSUs entitle the executives to receive a certain number of shares of our common stock based on our satisfaction of certain financial and strategic performance targets during 2021. These PSUs will vest over a three-year period, with the initial vesting occurring in March 2022. The number of shares underlying these March 2021 PSUs granted totaled 278,644 shares and had a grant date fair value of $99.05 per share. As of September 30, 2021, the performance-based milestones are expected to be partially achieved during 2021. PSUs with Financial and Strategic Performance Targets and RSUs PSUs with financial and strategic performance targets and RSUs are converted into shares of our common stock upon vesting on a one-for-one basis. Vesting of PSUs is subject to our achievement of specified financial and strategic performance targets in addition to the employee's continuing service to us while vesting of RSUs is subject to the employee’s continuing service to us. PSUs typically vest over three years while RSUs typically vest over three 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, 2020 4,816,000 $ 37.82 Granted 2,216,327 86.60 Released (2,391,951) 33.81 Forfeited (430,325) 44.84 Balance at September 30, 2021 4,210,051 $ 65.06 As of September 30, 2021, our total unrecognized share-based compensation expense related to RSUs and PSUs was approximately $170.2 million, which will be recognized over the remaining weighted-average vesting period of approximately 2.1 years.

Related-Party Transactions

Related-Party Transactions	9 Months Ended
	Sep. 30, 2021
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, 2021, we purchased $0.9 million and $1.9 million, respectively, of services from Adobe and during the three and nine months ended September 30, 2020, we purchased $0.3 million and $1.1 million, respectively, of services from Adobe. We had no revenues during the three and nine months ended September 30, 2021 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 payables as of September 30, 2021 and $0.1 million of payables as of December 31, 2020 to Adobe. We had no outstanding receivables as of September 30, 2021 and December 31, 2020 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, 2021, we incurred payment processing fees of $0.7 million and $2.1 million, respectively, and during the three and nine months ended September 30, 2020, we incurred payment processing fees of $0.5 million and $1.5 million, respectively, to PayPal. One of our board members is also a member of the Board of Directors of Zuora, Inc. (Zuora). During the three and nine months ended September 30, 2021, we purchased $1.4 million and $1.8 million, respectively, of services from Zuora and during the three and nine months ended September 30, 2020, we purchased $0.8 million and $1.2 million, respectively, of services from Zuora. We had $0.1 million of payables as of September 30, 2021 and no payables as of December 31, 2020 to Zuora.

Restructuring Charges

Restructuring Charges	9 Months Ended
	Sep. 30, 2021
Restructuring and Related Activities [Abstract]
Restructuring Charges	Restructuring ChargesIn September 2021, we changed our go-to-market strategy for our Thinkful product offering which we believe will have the most growth potential to serve learners. This resulted in a management approved restructuring plan that impacted approximately 60 full-time employees and 120 part-time employees in the United States. During the three months ended September 30, 2021, we recorded restructuring charges of $1.9 million related to one-time employee termination benefits classified on our condensed consolidated statements of operations based on the employees' job function. As of September 30, 2021, no payments have been made and the $1.9 million liability is included within accrued liabilities on our condensed consolidated balance sheets. We expect the total cost of the restructuring plan to be approximately $2.2 million and for it to be completed by the end of the second quarter of fiscal year 2022. We expect cost savings from the restructuring plan to be reinvested in future growth opportunities.

Background and Basis of Prese_2

Background and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated balance sheet as of September 30, 2021, the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive income (loss), and the condensed consolidated statements of stockholders' equity for the three and nine months ended September 30, 2021 and 2020, the condensed consolidated statements of cash flows for the nine months ended September 30, 2021 and 2020, 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, 2021, our results of operations, results of comprehensive income (loss), and stockholders' equity for the three and nine months ended September 30, 2021 and 2020, and cash flows for the nine months ended September 30, 2021 and 2020. Our results of operations, results of comprehensive income (loss), stockholders' equity, and cash flows for the nine months ended September 30, 2021 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, 2020 as 2020. 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, 2020 (the Annual Report on Form 10-K) filed with the U.S. Securities and Exchange Commission (SEC). Except for our policies on convertible senior notes, net, share-based compensation expense, and net income (loss) per share, 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. Our policies on convertible senior notes, net and net income (loss) per share were updated as a result of our adoption of Accounting Standards Update (ASU) 2020-06, Accounting for Convertible Instruments and Contracts in an Entity's Own Equity on January 1, 2021 under the modified retrospective method. For further information on ASU 2020-06, see the section below titled “Recent Accounting Pronouncements” of this Note 1, “Background and Basis of Presentation.”
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.” The notes, including the embedded conversion features, are accounted for under the traditional convertible debt accounting model entirely as a liability net of unamortized issuance costs. The carrying amount of the liability is classified as a current liability if we have committed to settle with current assets; otherwise, we classify it as a long-term liability as we retain the election to settle conversion requests in shares of our common stock. The embedded conversion features are not remeasured as long as they do not meet the separation requirement of a derivative; otherwise, they are classified as derivative instruments and recorded at fair value with changes in fair value recorded in other income (expense), net on our condensed consolidated statements of operations. The fair value of any derivative instruments related to the notes are determined utilizing Level 2 inputs. Issuance costs are amortized on a straight-line basis, which approximates the effective interest rate method, to interest expense over the term of the notes. In accounting for conversions of the notes, the carrying amount of the converted notes is reduced by the total consideration paid or issued for the respective converted notes and the
Share-based Compensation Expense	Share-based Compensation Expense Share-based compensation expense for restricted stock units (RSUs), performance-based restricted stock units (PSUs) with either a market-based condition or financial performance targets, and the employee stock purchase plan (ESPP) is accounted for under the fair value method based on the grant-date fair value of the award. Share-based compensation expense for RSUs and PSUs with financial performance targets is measured based on the closing fair market value of the Company’s common stock, PSUs with a market-based condition is estimated using a Monte Carlo simulation model, and the ESPP is estimated using the Black-Scholes-Merton option pricing model. We recognize share-based compensation expense, subject to continuing service over the requisite service period, which is generally the vesting period, on a straight-line basis for RSUs and the ESPP and on a graded basis for PSUs. Share-based compensation expense for PSUs with a market-based condition is recognized regardless of whether the market condition is satisfied whereas share-based compensation expense for PSUs with financial performance targets is recognized upon estimated or actual achievement of such targets. These amounts are reduced by estimated forfeitures, which are estimated at the time of the grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.
Net Income (Loss) Per Share	Net Income (Loss) Per Share Basic net income (loss) per share is computed by dividing net income (loss) by the weighted-average number of shares of common stock outstanding during the period. Diluted net income (loss) per share is computed by adjusting net income (loss) for all related interest expense and gains and losses recognized during the period, net of tax, and giving effect to all potential shares of common stock, including stock options, PSUs, RSUs, and shares related to convertible senior notes, to the extent dilutive. This assumes that all stock options and dilutive convertible shares were exercised or converted and is computed by applying the treasury stock method for outstanding stock options, PSUs, and RSUs, and the if-converted method for outstanding convertible senior notes. Under the treasury stock method, options, PSUs, and RSUs are assumed to be exercised or vested at the beginning of the period (or at the time of issuance, if later) and as if funds obtained thereby were used to purchase common stock at the average market price during the period. Under the if-converted method, outstanding convertible senior notes are assumed to be converted into common stock at the beginning of the period (or at the time of issuance, if later).
Use of Estimates	Use of EstimatesThe 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. 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.
Reclassification of Prior Period Presentation	Reclassification of Prior Period Presentation In order to conform with current period presentation, $6.6 million of current operating lease liabilities have been reclassified to accrued liabilities on our condensed consolidated balance sheet as of December 31, 2020. This change in presentation does not affect previously reported results.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Issued Accounting Pronouncements Not Yet Adopted In May 2021, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2021-04, Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options . ASU 2021-04 aims to clarify and reduce diversity in an issuer’s accounting for modifications or exchanges of freestanding equity-classified written call options that remain equity classified after modification or exchange based on the economic substance of the modification or exchange. Early adoption is permitted and the guidance must be applied prospectively to all modifications or exchanges that occur on or after the date of adoption. The guidance is effective for annual periods beginning after December 15, 2021, and we are currently in the process of evaluating the impact of this guidance. Recently Adopted Accounting Pronouncements In August 2020, the FASB issued 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 . Under ASU 2020-06, convertible instruments with embedded conversion features, that are not required to be accounted for as a derivative or that do not result in a substantial premium, are no longer required to be separated from the host contract thereby eliminating the cash conversion feature model. Instead, these convertible debt instruments will be accounted for as a single liability measured at amortized cost under the traditional convertible debt accounting model. ASU 2020-06 also requires the if-converted method to be applied for all convertible instruments when calculating diluted earnings per share. We adopted ASU 2020-06 on January 1, 2021 under the modified retrospective method applied to convertible senior notes outstanding as of January 1, 2021 and have not changed previously disclosed amounts or provided additional disclosures for comparative periods. Adoption of ASU 2020-06 resulted in an increase to convertible senior notes of $378.1 million and a decrease to additional paid-in capital of $465.0 million due to the application of the traditional convertible debt model and no longer separating the embedded conversion feature. Accumulated deficit also decreased by $86.9 million due to the reduction in non-cash interest expense related to the debt discount and we expect interest expense to decrease in future periods. Refer to Note 7, “Convertible Senior Notes” for more information.

Background and Basis of Prese_3

Background and Basis of Presentation (Tables)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Other Nonoperating Income (Expense)	Other income (expense), net consists of the following (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Loss on early extinguishment of debt (1) $ — $ (3,315) $ (78,152) $ (3,315) Loss on change in fair value of derivative instruments, net (1) — — (7,148) — Gain on sale of strategic equity investments (2) 7,158 — 12,496 — Interest income 1,485 2,539 5,385 10,588 Other 27 (28) 801 123 Total other income (expense), net $ 8,670 $ (804) $ (66,618) $ 7,396 (1) For further information, see Note 7, “Convertible Senior Notes.” (2) For further information, see Note 4, “Cash and Cash Equivalents, and Investments.”

Revenues (Tables)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2021
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 Change 2021 2020 $ % Chegg Services $ 146,790 $ 118,895 $ 27,895 23 % Required Materials 25,152 35,123 (9,971) (28) Total net revenues $ 171,942 $ 154,018 $ 17,924 12 Nine Months Ended Change 2021 2020 $ % Chegg Services $ 482,654 $ 345,258 $ 137,396 40 % Required Materials 86,144 93,359 (7,215) (8) Total net revenues $ 568,798 $ 438,617 $ 130,181 30
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, December 31, 2020 $ % Accounts receivable, net $ 9,302 $ 12,913 $ (3,611) (28) % Deferred revenue 49,983 32,620 17,363 53 Contract assets 16,358 13,243 3,115 24

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the computation of basic and diluted net income (loss) per share (in thousands, except per share amounts): Three Months Ended Nine Months Ended 2021 2020 (1) 2021 2020 (1) Basic Numerator: Net income (loss) $ 6,651 $ (37,140) $ (25,764) $ (32,264) Denominator: Weighted average shares used to compute net income (loss) per share, basic 144,746 126,194 140,775 124,162 Net income (loss) per share, basic $ 0.05 $ (0.29) $ (0.18) $ (0.26) Diluted Numerator: Net income (loss), diluted $ 6,651 $ (37,140) $ (25,764) $ (32,264) Denominator: Weighted average shares used to compute net income (loss) per share, basic 144,746 126,194 140,775 124,162 Options to purchase common stock 485 — — — PSUs and RSUs 1,462 — — — Employee stock purchase plan 6 — — — Weighted average shares used to compute net income (loss) per share, diluted 146,699 126,194 140,775 124,162 Net income (loss) per share, diluted $ 0.05 $ (0.29) $ (0.18) $ (0.26) (1) As noted above, prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method.
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 income (loss) per share because including them would have been anti-dilutive (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Options to purchase common stock — 865 515 977 PSUs and RSUs 849 3,394 2,210 3,425 Shares related to convertible senior notes 22,875 8,721 23,876 4,422 Employee stock purchase plan — 9 2 4 Total common stock equivalents 23,724 12,989 26,603 8,828

Cash and Cash Equivalents, an_2

Cash and Cash Equivalents, and Investments (Tables)	9 Months Ended
	Sep. 30, 2021
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, 2021 and December 31, 2020 (in thousands): September 30, 2021 Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 29,338 $ — $ — $ 29,338 Money market funds 684,499 — — 684,499 Total cash and cash equivalents $ 713,837 $ — $ — $ 713,837 Short-term investments: Commercial paper $ 364,098 $ 49 $ (4) $ 364,143 Corporate debt securities 658,525 280 (122) 658,683 Agency bonds 15,501 18 — 15,519 Total short-term investments $ 1,038,124 $ 347 $ (126) $ 1,038,345 Long-term investments: Corporate debt securities $ 813,889 $ 142 $ (531) $ 813,500 Total long-term investments $ 813,889 $ 142 $ (531) $ 813,500 December 31, 2020 Adjusted Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 15,054 $ — $ — $ 15,054 Money market funds 464,799 — — 464,799 Total cash and cash equivalents $ 479,853 $ — $ — $ 479,853 Short-term investments: Commercial paper $ 204,152 $ 24 $ (6) $ 204,170 Corporate debt securities 459,967 1,478 (48) 461,397 Total short-term investments $ 664,119 $ 1,502 $ (54) $ 665,567 Long-term investments: Corporate debt securities $ 484,275 $ 605 $ (283) $ 484,597 Agency bonds 38,995 36 — 39,031 Total long-term investments $ 523,270 $ 641 $ (283) $ 523,628
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, 2021 (in thousands): Adjusted Cost Fair Value Due in 1 year or less $ 1,038,124 $ 1,038,345 Due in 1-2 years 813,889 813,500 Investments not due at a single maturity date 684,499 684,499 Total $ 2,536,512 $ 2,536,344

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2021
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, 2021 and December 31, 2020 are classified based on the valuation technique level in the tables below (in thousands): September 30, 2021 Total Level 1 Level 2 Assets: Cash equivalents: Money market funds $ 684,499 $ 684,499 $ — Short-term investments: Commercial paper 364,143 — 364,143 Corporate debt securities 658,683 — 658,683 Agency bonds 15,519 — 15,519 Long-term investments: Corporate debt securities 813,500 — 813,500 Total assets measured and recorded at fair value $ 2,536,344 $ 684,499 $ 1,851,845 December 31, 2020 Total Level 1 Level 2 Assets: Cash equivalents: Money market funds $ 464,799 $ 464,799 $ — Short-term investments: Commercial paper 204,170 — 204,170 Corporate debt securities 461,397 — 461,397 Long-term investments: Corporate debt securities 484,597 — 484,597 Agency bonds 39,031 — 39,031 Total assets measured and recorded at fair value $ 1,653,994 $ 464,799 $ 1,189,195
Fair Value Measurements, Nonrecurring	The carrying amounts and estimated fair values of the notes as of September 30, 2021 and December 31, 2020 are as follows (in thousands): September 30, 2021 December 31, 2020 (1) Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value 2026 notes $ 987,027 $ 984,880 $ 761,930 $ 1,129,370 2025 notes 689,722 1,011,050 640,614 1,456,800 2023 notes — — 104,378 376,949 Convertible senior notes, net $ 1,676,749 $ 1,995,930 $ 1,506,922 $ 2,963,119 (1) Prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method. Refer to Note 7, “Convertible Senior Notes” for more information.

Convertible Senior Notes (Table

Convertible Senior Notes (Tables)	9 Months Ended
	Sep. 30, 2021
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 notes is as follows (in thousands): September 30, 2021 December 31, 2020 (1) 2026 Notes 2025 Notes 2026 Notes 2025 Notes 2023 Notes Principal $ 1,000,000 $ 699,989 $ 1,000,000 $ 800,000 $ 115,576 Unamortized debt discount — — (226,732) (149,138) (9,953) Unamortized issuance costs (12,973) (10,267) (11,338) (10,248) (1,245) Net carrying amount $ 987,027 $ 689,722 $ 761,930 $ 640,614 $ 104,378 (1) As noted above, prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method.
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, 2021 2020 (1) 2026 Notes 2025 Notes 2026 Notes 2025 Notes 2023 Notes Contractual interest expense $ — $ 221 $ — $ 252 $ 169 Amortization of debt discount — — 4,491 8,938 2,458 Amortization of issuance costs 663 749 225 614 292 Total interest expense $ 663 $ 970 $ 4,716 $ 9,804 $ 2,919 (1) As noted above, prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method . Nine Months Ended September 30, 2021 2020 (1) 2026 Notes 2025 Notes 2023 Notes 2026 Notes 2025 Notes 2023 Notes Contractual interest expense $ — $ 676 $ 78 $ — $ 750 $ 599 Amortization of debt discount — — — 4,491 26,621 8,709 Amortization of issuance costs 1,970 2,297 242 225 1,829 1,035 Total interest expense $ 1,970 $ 2,973 $ 320 $ 4,716 $ 29,200 $ 10,343 (1) As noted above, prior period amounts have not been adjusted due to the adoption of ASU 2020-06 under the modified retrospective method .

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2021
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 Nine Months Ended 2021 2020 2021 2020 Cost of revenues $ 393 $ 262 $ 1,174 $ 644 Research and development 8,917 8,433 25,976 23,044 Sales and marketing 3,051 2,431 9,625 7,053 General and administrative 12,151 10,403 39,382 28,668 Total share-based compensation expense $ 24,512 $ 21,529 $ 76,157 $ 59,409
Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions	The following table summarizes the key assumptions used to determine the fair value of the awards: Expected term (years) 3.00 Expected volatility 49.04 % Expected dividends — % Risk-free interest rate 0.27 %
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, 2020 4,816,000 $ 37.82 Granted 2,216,327 86.60 Released (2,391,951) 33.81 Forfeited (430,325) 44.84 Balance at September 30, 2021 4,210,051 $ 65.06

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, 2021	Dec. 31, 2020	Mar. 31, 2019
2026 Notes
Debt Instrument [Line Items]
Face value	$ 1,000,000,000			$ 1,000,000,000	$ 1,000,000,000
Interest rate, stated percentage	0.00%
Proceeds from issuance of debt	$ 1,000,000,000
2025 Notes
Debt Instrument [Line Items]
Face value		$ 100,000,000		$ 699,989,000	800,000,000	$ 700,000,000
Interest rate, stated percentage						0.125%
Proceeds from issuance of debt		$ 800,000,000
2023 Notes
Debt Instrument [Line Items]
Face value			$ 345,000,000		$ 115,576,000
Interest rate, stated percentage			0.25%
Proceeds from issuance of debt			$ 345,000,000

Background and Basis of Prese_5

Background and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 30, 2021	Jan. 01, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Accrued liabilities	$ 73,320			$ 68,565
Equity	1,354,517	$ 1,337,882		609,635	$ 645,392	$ 498,378	$ 498,829
Additional Paid-In Capital
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity	1,717,421	1,706,855		1,030,577	1,092,574	907,908	916,095
Accumulated Deficit
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity	$ (361,497)	$ (368,148)		(422,601)	$ (448,644)	$ (411,504)	(416,292)
Cumulative Effect, Period of Adoption, Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity				(378,138)			(88)
Cumulative Effect, Period of Adoption, Adjustment | Additional Paid-In Capital
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity				(465,006)
Cumulative Effect, Period of Adoption, Adjustment | Accumulated Deficit
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity				86,868			$ (88)
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06 | Additional Paid-In Capital
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity			$ (465,000)
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06 | Accumulated Deficit
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity			86,900
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06 | Senior Notes
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity			$ 378,100
Revision of Prior Period, Reclassification, Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Current operating lease liabilities				(6,600)
Accrued liabilities				$ 6,600

Background and Basis of Prese_6

Background and Basis of Presentation - Other Income (Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Loss on early extinguishment of debt	$ 0	$ (3,315)	$ (78,152)	$ (3,315)
Loss on change in fair value of derivative instruments, net	0	0	(7,148)	0
Gain on sale of strategic equity investments	7,158	0	12,496	0
Interest income	1,485	2,539	5,385	10,588
Other	27	(28)	801	123
Total other income (expense), net	$ 8,670	$ (804)	$ (66,618)	$ 7,396

Revenues - Disaggregation of Re

Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total net revenues	$ 171,942	$ 154,018	$ 568,798	$ 438,617
Change, Total net revenues	$ 17,924		$ 130,181
Change, Total net revenues, percent	12.00%		30.00%
Chegg Services
Disaggregation of Revenue [Line Items]
Total net revenues	$ 146,790	118,895	$ 482,654	345,258
Change, Total net revenues	$ 27,895		$ 137,396
Change, Total net revenues, percent	23.00%		40.00%
Required Materials
Disaggregation of Revenue [Line Items]
Total net revenues	$ 25,152	$ 35,123	$ 86,144	$ 93,359
Change, Total net revenues	$ (9,971)		$ (7,215)
Change, Total net revenues, percent	(28.00%)		(8.00%)

Revenues - Additional Informati

Revenues - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Contract with customer, liability, revenue recognized	$ 31,300	$ 25,400	$ 32,600	$ 18,000
Contract with customer, liability, revenue recognized, prior period	0		3,400
Accounts receivable, net			$ (3,611)
Accounts receivable, net, percent			(28.00%)
Deferred revenue			$ 17,363
Deferred revenue, percent			53.00%
Contract assets			$ 3,115
Contract assets, percent			24.00%
Textbook Library
Disaggregation of Revenue [Line Items]
Operating lease income	$ 6,200	$ 12,000	$ 26,900	$ 35,400

Revenues - Contract Balances (D

Revenues - Contract Balances (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Accounts receivable, net	$ 9,302	$ 12,913
Change, Accounts receivable, net	$ (3,611)
Change, Accounts receivable, net, percent	(28.00%)
Deferred revenue	$ 49,983	32,620
Change, Deferred revenue	$ 17,363
Change, Deferred revenue, percent	53.00%
Contract assets	$ 16,358	$ 13,243
Change, Contract assets	$ 3,115
Change, Contract assets, percent	24.00%

Net Income (Loss) Per Share - C

Net Income (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, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income (loss)	$ 6,651	$ (37,140)	$ (25,764)	$ (32,264)
Denominator:
Weighted average shares used to compute net income (loss) per share, basic (in shares)	144,746	126,194	140,775	124,162
Weighted average shares used to compute net income (loss) per share, diluted (in shares)	146,699	126,194	140,775	124,162
Net income (loss) per share, basic (in dollars per share)	$ 0.05	$ (0.29)	$ (0.18)	$ (0.26)
Net income (loss) per share, diluted (in dollars per share)	$ 0.05	$ (0.29)	$ (0.18)	$ (0.26)
Options to purchase common stock
Denominator:
Incremental common shares attributable to dilutive effect (in shares)	485	0	0	0
PSUs and RSUs
Denominator:
Incremental common shares attributable to dilutive effect (in shares)	1,462	0	0	0
Employee stock purchase plan
Denominator:
Incremental common shares attributable to dilutive effect (in shares)	6	0	0	0

Net Income (Loss) Per Share - S

Net Income (Loss) Per Share - Shares Excluded From Computation Of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	23,724	12,989	26,603	8,828
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	0	865	515	977
PSUs and RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	849	3,394	2,210	3,425
Shares related to convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	22,875	8,721	23,876	4,422
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents (in shares)	0	9	2	4

Cash and Cash Equivalents, an_3

Cash and Cash Equivalents, and Investments - Schedule of Available For Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	$ 2,536,512
Fair Value	2,536,344
Cash and cash equivalents:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	713,837	$ 479,853
Unrealized Gain	0	0
Unrealized Loss	0	0
Fair Value	713,837	479,853
Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	1,038,124	664,119
Unrealized Gain	347	1,502
Unrealized Loss	(126)	(54)
Fair Value	1,038,345	665,567
Long-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	813,889	523,270
Unrealized Gain	142	641
Unrealized Loss	(531)	(283)
Fair Value	813,500	523,628
Commercial paper | Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	364,098	204,152
Unrealized Gain	49	24
Unrealized Loss	(4)	(6)
Fair Value	364,143	204,170
Corporate debt securities | Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	658,525	459,967
Unrealized Gain	280	1,478
Unrealized Loss	(122)	(48)
Fair Value	658,683	461,397
Corporate debt securities | Long-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	813,889	484,275
Unrealized Gain	142	605
Unrealized Loss	(531)	(283)
Fair Value	813,500	484,597
Agency bonds | Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	15,501
Unrealized Gain	18
Unrealized Loss	0
Fair Value	15,519
Agency bonds | Long-term investments:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost		38,995
Unrealized Gain		36
Unrealized Loss		0
Fair Value		39,031
Cash | Cash and cash equivalents:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	29,338	15,054
Unrealized Gain	0	0
Unrealized Loss	0	0
Fair Value	29,338	15,054
Money market funds | Cash and cash equivalents:
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	684,499	464,799
Unrealized Gain	0	0
Unrealized Loss	0	0
Fair Value	$ 684,499	$ 464,799

Cash and Cash Equivalents, an_4

Cash and Cash Equivalents, and Investments - Contractual Maturity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Adjusted Cost
Due in 1 year or less, Adjusted Cost	$ 1,038,124
Due in 1-2 years, Adjusted Cost	813,889
Investments not due at a single maturity date, Adjusted Cost	684,499
Adjusted Cost	2,536,512
Fair Value
Due in 1 year or less, Fair Value	1,038,345
Due in 1-2 years, Fair Value	813,500
Investments not due at a single maturity date, Fair Value	684,499
Total, Fair Value	$ 2,536,344
Weighted average maturity	12 months

Cash and Cash Equivalents, an_5

Cash and Cash Equivalents, and Investments - Strategic Investment (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Mar. 31, 2020	Mar. 31, 2017
Schedule of Investments [Line Items]
Gain on sale of strategic equity investments			$ 7,158	$ 0	$ 12,496	$ 0
Proceeds from sale of strategic equity investments					16,076	0
Impairment charge					$ 0	$ 10,000
TAPD, Inc.
Schedule of Investments [Line Items]
Cost method investment								$ 2,000
Consideration received on sale	$ 9,200
Gain on sale of strategic equity investments	7,200
Proceeds from sale of strategic equity investments	$ 9,000
Foreign Entity
Schedule of Investments [Line Items]
Cost method investment									$ 3,000
Consideration received on sale		$ 8,300
Gain on sale of strategic equity investments		5,300
Proceeds from sale of strategic equity investments		$ 7,100
WayUp, Inc.
Schedule of Investments [Line Items]
Impairment charge							$ 10,000

Fair Value Measurement - Financ

Fair Value Measurement - Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 1,038,345	$ 665,567
Long-term investments	813,500	523,628
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	2,536,344	1,653,994
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	684,499	464,799
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	1,851,845	1,189,195
Commercial paper | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	364,143	204,170
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	364,143	204,170
Corporate debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	658,683	461,397
Long-term investments	813,500	484,597
Corporate debt 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 debt securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	658,683	461,397
Long-term investments	813,500	484,597
Agency bonds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	15,519
Long-term investments		39,031
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
Agency bonds | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	15,519
Long-term investments		39,031
Money market funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	684,499	464,799
Money market funds | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	684,499	464,799
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

Fair Value Measurement - Debt (

Fair Value Measurement - Debt (Details) - Senior Notes - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Carrying Amount | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	$ 1,676,749	$ 1,506,922
Estimated Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	1,995,930	2,963,119
2026 notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unamortized issuance costs	(12,973)	(11,338)
Unamortized debt discount	0	(226,732)
2026 notes | Carrying Amount | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	987,027	761,930
2026 notes | Estimated Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	984,880	1,129,370
2025 notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unamortized issuance costs	(10,267)	(10,248)
Unamortized debt discount	0	(149,138)
2025 notes | Carrying Amount | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	689,722	640,614
2025 notes | Estimated Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	1,011,050	1,456,800
2023 notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unamortized issuance costs		(1,245)
Unamortized debt discount		(9,953)
2023 notes | Carrying Amount | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	0	104,378
2023 notes | Estimated Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible senior notes	$ 0	$ 376,949

Acquisition (Details)

Acquisition (Details) - USD ($) $ in Thousands	Feb. 22, 2021	Sep. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill		$ 290,499	$ 285,214
Technology Company
Business Acquisition [Line Items]
Ownership percent of stock acquired	100.00%
Initial cash consideration	$ 8,000
Acquired assets	400
Intangible assets	3,300
Goodwill	5,800
Liabilities assumed	$ 1,500

Convertible Senior Notes - Addi

Convertible Senior Notes - Additional Information (Details)	1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)shares	Aug. 31, 2020USD ($)	Apr. 30, 2019USD ($)	Apr. 30, 2018USD ($)day	Sep. 30, 2021USD ($)$ / shares	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)shares	Mar. 31, 2019USD ($)
Debt Instrument [Line Items]
Repayments of convertible senior notes							$ 300,755,000	$ 159,677,000
Equity component on conversions of 2023 notes and 2025 notes						$ 237,462,000	(236,920,000)	237,462,000
Proceeds from exercise of convertible senior notes capped call							69,005,000	57,414,000
Loss on early extinguishment of debt					$ 0	$ 3,315,000	78,152,000	$ 3,315,000
Senior Notes | 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 | 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 | 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 | Fundamental Change Scenario
Debt Instrument [Line Items]
Threshold percentage of stock price trigger				100.00%
Senior Notes | 2026 Notes
Debt Instrument [Line Items]
Face value		$ 1,000,000,000			$ 1,000,000,000		$ 1,000,000,000		$ 1,000,000,000
Interest rate, stated percentage		0.00%
Proceeds from issuance of debt		$ 1,000,000,000
Conversion ratio		0.0092978
Conversion price (in dollars per share) | $ / shares					$ 107.55		$ 107.55
Senior Notes | 2026 Notes | Capped Call
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares					$ 156.44		$ 156.44
Senior Notes | 0% Convertible Senior Notes Due 2026, Additional Notes
Debt Instrument [Line Items]
Face value		$ 100,000,000
Senior Notes | 2025 Notes
Debt Instrument [Line Items]
Face value			$ 100,000,000		$ 699,989,000		$ 699,989,000		800,000,000	$ 700,000,000
Interest rate, stated percentage										0.125%
Proceeds from issuance of debt			$ 800,000,000
Repurchased principal amount					$ 100,000,000		100,000,000
Repayments of convertible senior notes	$ 184,900,000						$ 184,900,000
Carrying amount	98,300,000
Debt extinguished	100,000,000
Derivative liability	176,500,000
Gain (loss) in change in fair value	(8,400,000)
Loss on early extinguishment of debt	$ 78,200,000
Conversion ratio			0.0193956
Conversion price (in dollars per share) | $ / shares					$ 51.56		$ 51.56
Senior Notes | 2025 Notes | Capped Call
Debt Instrument [Line Items]
Debt instrument, convertible, shares terminated (in shares) | shares	1,939,560
Proceeds from exercise of convertible senior notes capped call	$ 23,900,000
Derivative liability	22,600,000
Gain (loss) in change in fair value	$ 1,300,000
Conversion price (in dollars per share) | $ / shares					$ 79.32		$ 79.32
Senior Notes | 2023 Notes
Debt Instrument [Line Items]
Face value				$ 345,000,000					115,576,000
Interest rate, stated percentage				0.25%
Proceeds from issuance of debt				$ 345,000,000
Option to purchase additional notes				$ 45,000,000
Repurchased principal amount					$ 115,600,000		$ 115,600,000
Aggregate consideration							351,100,000
Repayments of convertible senior notes							$ 115,600,000
Debt conversion, shares issued (in shares) | shares							2,983,011
Debt conversion, shares issued, value							$ 235,500,000
Carrying amount					$ 114,200,000		114,200,000
Equity component on conversions of 2023 notes and 2025 notes							$ 236,900,000
Conversion ratio				0.0371051
Conversion price (in dollars per share) | $ / shares					$ 26.95		$ 26.95
Senior Notes | 2023 Notes | Requests For Conversions
Debt Instrument [Line Items]
Repurchased principal amount					$ 24,700,000		$ 24,700,000
Senior Notes | 2023 Notes | Election Of Option To Redeem Outstanding Notes
Debt Instrument [Line Items]
Repurchased principal amount					$ 90,900,000		$ 90,900,000
Senior Notes | 2023 Notes | Capped Call
Debt Instrument [Line Items]
Debt instrument, convertible, shares terminated (in shares) | shares							4,288,459
Proceeds from exercise of convertible senior notes capped call							$ 45,200,000
Senior Notes | 2023 Notes | Exchange Of Aggregate Principal Amount
Debt Instrument [Line Items]
Repurchased principal amount									172,000,000
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
Aggregate consideration for principal amount exchanged									$ 501,700,000

Convertible Senior Notes - Long

Convertible Senior Notes - Long-term Debt Instruments (Details) - USD ($) $ in Thousands	1 Months Ended			9 Months Ended
	Aug. 31, 2020	Apr. 30, 2019	Apr. 30, 2018	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Net proceeds				$ 0	$ 984,096
2026 Notes | Senior Notes
Debt Instrument [Line Items]
Principal amount	$ 1,000,000
Less initial purchasers’ discount	(15,000)
Less other issuance costs	(904)
Net proceeds	$ 984,096
2025 Notes | Senior Notes
Debt Instrument [Line Items]
Principal amount		$ 800,000
Less initial purchasers’ discount		(18,998)
Less other issuance costs		(822)
Net proceeds		$ 780,180
2023 Notes | Senior Notes
Debt Instrument [Line Items]
Principal amount			$ 345,000
Less initial purchasers’ discount			(8,625)
Less other issuance costs			(757)
Net proceeds			$ 335,618

Convertible Senior Notes - Net

Convertible Senior Notes - Net Carrying Amount (Details) - Senior Notes - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Aug. 31, 2020	Apr. 30, 2019	Mar. 31, 2019	Apr. 30, 2018
Carrying Amount | Fair Value, Measurements, Nonrecurring
Debt Instrument [Line Items]
Net carrying amount	$ 1,676,749,000	$ 1,506,922,000
2026 Notes
Debt Instrument [Line Items]
Principal	1,000,000,000	1,000,000,000	$ 1,000,000,000
Unamortized debt discount	0	(226,732,000)
Unamortized issuance costs	(12,973,000)	(11,338,000)
2026 Notes | Carrying Amount | Fair Value, Measurements, Nonrecurring
Debt Instrument [Line Items]
Net carrying amount	987,027,000	761,930,000
2025 Notes
Debt Instrument [Line Items]
Principal	699,989,000	800,000,000		$ 100,000,000	$ 700,000,000
Unamortized debt discount	0	(149,138,000)
Unamortized issuance costs	(10,267,000)	(10,248,000)
2025 Notes | Carrying Amount | Fair Value, Measurements, Nonrecurring
Debt Instrument [Line Items]
Net carrying amount	689,722,000	640,614,000
2023 Notes
Debt Instrument [Line Items]
Principal		115,576,000				$ 345,000,000
Unamortized debt discount		(9,953,000)
Unamortized issuance costs		(1,245,000)
2023 Notes | Carrying Amount | Fair Value, Measurements, Nonrecurring
Debt Instrument [Line Items]
Net carrying amount	$ 0	$ 104,378,000

Convertible Senior Notes - Inte

Convertible Senior Notes - Interest Expense Recognized (Details) - Senior Notes - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
2026 Notes
Debt Instrument [Line Items]
Contractual interest expense	$ 0	$ 0	$ 0	$ 0
Amortization of debt discount	0	4,491	0	4,491
Amortization of issuance costs	663	225	1,970	225
Total interest expense	663	4,716	1,970	4,716
2025 Notes
Debt Instrument [Line Items]
Contractual interest expense	221	252	676	750
Amortization of debt discount	0	8,938	0	26,621
Amortization of issuance costs	749	614	2,297	1,829
Total interest expense	$ 970	9,804	2,973	29,200
2023 Notes
Debt Instrument [Line Items]
Contractual interest expense		169	78	599
Amortization of debt discount		2,458	0	8,709
Amortization of issuance costs		292	242	1,035
Total interest expense		$ 2,919	$ 320	$ 10,343

Convertible Senior Notes - Capp

Convertible Senior Notes - Capped Call (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		9 Months Ended
	Aug. 31, 2020	Apr. 30, 2019	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Proceeds from issuance of convertible senior notes, net of issuance costs			$ 0	$ 984,096
2026 Notes | Senior Notes
Debt Instrument [Line Items]
Proceeds from issuance of convertible senior notes, net of issuance costs	$ 984,096
Conversion price (in dollars per share)			$ 107.55
2025 Notes | Senior Notes
Debt Instrument [Line Items]
Proceeds from issuance of convertible senior notes, net of issuance costs		$ 780,180
Conversion price (in dollars per share)			$ 51.56
Capped Call | 2026 Notes | Senior Notes
Debt Instrument [Line Items]
Proceeds from issuance of convertible senior notes, net of issuance costs	$ 103,400
Debt instrument, convertible (in shares)			9,297,800
Conversion price (in dollars per share)			$ 156.44
Capped Call | 2025 Notes | Senior Notes
Debt Instrument [Line Items]
Proceeds from issuance of convertible senior notes, net of issuance costs		$ 97,200
Debt instrument, convertible (in shares)			13,576,706
Conversion price (in dollars per share)			$ 79.32

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	Aug. 12, 2020claim	Jul. 01, 2020claim	May 12, 2020USD ($)claim	Jul. 21, 2020USD ($)
VitalSource Technologies LLC (VST) vs. Chegg | Pending Litigation
Loss Contingencies [Line Items]
Estimate of possible loss | $				$ 75
2018 Data Incident, Arbitration Demands
Loss Contingencies [Line Items]
Loss contingency, number of arbitration demands filed | claim	577
2018 Data Incident, Arbitration Demands | Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, number of arbitration demands filed | claim		1,007	15,107
Loss contingency, damages sought, value | $			$ 25

Stockholders' Equity - Equity O

Stockholders' Equity - Equity Offering (Details) - Public Offering $ / shares in Units, $ in Millions	1 Months Ended
	Feb. 28, 2021USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued and sold (in shares) | shares	10,974,600
Offering price per share (in dollars per share | $ / shares	$ 102
Proceeds from offering	$ 1,091.5
Underwriting discounts and commissions	26.9
Offering expenses	$ 1.1

Stockholders' Equity - Securiti

Stockholders' Equity - Securities Repurchase Program (Details) - USD ($) $ in Thousands	Nov. 01, 2021	Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repayments of convertible senior notes			$ 300,755	$ 159,677
Remaining under repurchase program			665,500
2025 Notes | Senior Notes
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchased principal amount			100,000
Repayments of convertible senior notes		$ 184,900	$ 184,900
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program, increase of authorized amount	$ 500,000
Stock repurchase program, authorized amount	$ 1,000,000

Stockholders' Equity - Share-ba

Stockholders' Equity - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 24,512	$ 21,529	$ 76,157	$ 59,409
Share-based compensation expense capitalized	600		1,800
Cost of revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	393	262	1,174	644
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	8,917	8,433	25,976	23,044
Sales and marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	3,051	2,431	9,625	7,053
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 12,151	$ 10,403	$ 39,382	$ 28,668

Stockholders' Equity - 2021 PSU

Stockholders' Equity - 2021 PSU Grants with Market-Based Conditions (Details) - PSUs with Market Based Conditions	1 Months Ended		9 Months Ended
	Mar. 31, 2024	Mar. 31, 2021$ / sharesshares	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target level of award		100.00%
Consecutive trading days achieving maximum average market value		60 days
Performance period		3 years
Grants in period (in shares) | shares		732,260
Grant date fair value (in dollars per share) | $ / shares		$ 68.55
Conversion ratio			1
Vesting period		4 years	4 years
Expected term (years)			3 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued as percent of target level of achieving maximum average market value		50.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued as percent of target level of achieving maximum average market value		150.00%
Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	50.00%
Threshold Level
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market value per share price minimum threshold (in dollars per share) | $ / shares		$ 123.81
Stock issued based on achieving target levels (in shares) | shares		244,086
Target Level
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market value per share price minimum threshold (in dollars per share) | $ / shares		$ 148.58
Stock issued based on achieving target levels (in shares) | shares		488,173
Maximum Level
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market value per share price minimum threshold (in dollars per share) | $ / shares		$ 173.34
Stock issued based on achieving target levels (in shares) | shares		732,260

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Assumptions (Details) - PSUs with Market Based Conditions	9 Months Ended
	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)	3 years
Expected volatility	49.04%
Expected dividends	0.00%
Risk-free interest rate	0.27%

Stockholders' Equity - 2021 P_2

Stockholders' Equity - 2021 PSU Grants with Financial and Strategic Performance Targets (Details)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
PSUs with Financial and Strategic Performance Targets
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Grants in period (in shares) | shares	278,644
Grant date fair value (in dollars per share) | $ / shares	$ 99.05
Conversion ratio	1
Restricted Stock Units (RSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Restricted Stock Units (RSUs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Restricted Stock Unit Activity (Details) - PSUs and RSUs - $ / shares	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Shares Outstanding
Beginning balance (in shares)	4,816,000
Granted (in shares)	2,216,327
Released (in shares)	(2,391,951)
Forfeited (in shares)	(430,325)
Ending balance (in shares)	4,210,051
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, outstanding balance (in dollars per share)	$ 65.06	$ 37.82
Weighted Average Grant Date Fair Value, Granted (in dollars per share)	86.60
Weighted Average Grant Date Fair Value, Released (in dollars per share)	33.81
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share)	$ 44.84

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - PSUs and RSUs $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to restricted stock units	$ 170.2
Weighted average vesting period for recognition of compensation expense	2 years 1 month 6 days

Related-Party Transactions (Det

Related-Party Transactions (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)board_member	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Adobe Systems | Chief Executive Officer
Related Party Transaction [Line Items]
Purchases from related party	$ 0.9	$ 0.3	$ 1.9	$ 1.1
Revenue from related parties	0	0	0	0.1
Due to related parties	0		0		$ 0.1
Receivables from related party	0		$ 0		0
PayPal Holdings, Inc. | Immediate Family Member of Management or Principal Owner | Payment Processing Fees
Related Party Transaction [Line Items]
Number of board members appointed to board of directors of related party | board_member			1
Expenses from transactions with related party	0.7	0.5	$ 2.1	1.5
Zuora, Inc. | Board Of Directors Member
Related Party Transaction [Line Items]
Purchases from related party	1.4	$ 0.8	1.8	$ 1.2
Due to related parties	$ 0.1		$ 0.1		$ 0
Number of board members appointed to Board of Directors of related party | board_member			1

Restructuring Charges (Details)

Restructuring Charges (Details) $ in Millions	1 Months Ended		3 Months Ended
	Sep. 30, 2021USD ($)full_time_employee	Sep. 30, 2021USD ($)part_time_employee	Sep. 30, 2021USD ($)
Restructuring and Related Activities [Abstract]
Number of positions impacted	60	120
Restructuring charges			$ 1.9
Restructuring liability	$ 1.9	$ 1.9	1.9
Expected cost restructuring plan	$ 2.2	$ 2.2	$ 2.2

Uncategorized Items - chgg-2021

Label	Element	Value
Accounting Standards Update [Extensible Enumeration]	us-gaap_AccountingStandardsUpdateExtensibleList	Accounting Standards Update 2016-13 [Member]