Debt Conversion, Requested Amount

No definition available.

Name:	chgg_DebtConversionRequestedAmount
Namespace Prefix:	chgg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Debt Instrument, Consideration Transferred, Equity Interests Issued And Issuable

+ References

No definition available.

+ Details

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Namespace Prefix:	chgg_
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Balance Type:	credit
Period Type:	duration

- Definition

Debt Instrument, Convertible, If-Converted Value Less Than Principal

+ References

No definition available.

+ Details

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Namespace Prefix:	chgg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Debt Instrument, Convertible, Shares

+ References

No definition available.

+ Details

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Namespace Prefix:	chgg_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Convertible, Shares Terminated

+ References

No definition available.

+ Details

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Namespace Prefix:	chgg_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Face Amount, Option To Purchase Additional Notes

+ References

No definition available.

+ Details

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Namespace Prefix:	chgg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt Instrument, Maturity Date, Remaining Useful Life

+ References

No definition available.

+ Details

Name:	chgg_DebtInstrumentMaturityDateRemainingUsefulLife
Namespace Prefix:	chgg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Principal Amount Exchanged, Consideration Transferred

+ References

No definition available.

+ Details

Name:	chgg_DebtInstrumentPrincipalAmountExchangedConsiderationTransferred
Namespace Prefix:	chgg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Payments For Initial Purchasers Discount

+ References

No definition available.

+ Details

Name:	chgg_PaymentsForInitialPurchasersDiscount
Namespace Prefix:	chgg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The value of the financial instrument(s) that the original debt is being converted into in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

+ References

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Balance Type:	na
Period Type:	duration

- Definition

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

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-Name Accounting Standards Codification
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-Paragraph 4
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Balance Type:	credit
Period Type:	instant

- Definition

The price per share of the conversion feature embedded in the debt instrument.

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Balance Type:	na
Period Type:	instant

- Definition

Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

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Period Type:	duration

- Definition

The amount by which the convertible debt's if-converted value exceeds its principle amount at the balance sheet date, regardless of whether the instrument is currently convertible. This element applies to public companies only.

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-SubTopic 20
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Balance Type:	credit
Period Type:	duration

- Definition

Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

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Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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+ Details

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Period Type:	duration

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt.

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+ Details

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Period Type:	duration

- Definition

The cash inflow from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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- Definition

The cash outflow from the repayment of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

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- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

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Period Type:	instant

- Details

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- Details

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- Details

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Convertible Senior Notes - Convertible Senior Notes (Details)	1 Months Ended			2 Months Ended	12 Months Ended
	Aug. 31, 2020 USD ($)	Apr. 30, 2019 USD ($)	Apr. 30, 2018 USD ($) day	Feb. 22, 2021 USD ($)	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Mar. 31, 2019 USD ($)
Debt Instrument [Line Items]
Net proceeds					$ 984,096,000	$ 780,180,000	$ 335,618,000
Repayments of convertible senior notes					303,967,000	0	0
Loss on early extinguishments of debt					4,286,000	0	0
Proceeds from exercise of convertible senior notes capped call					$ 77,095,000	0	$ 0
0.25% Convertible Senior Notes Due 2023 \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount requests for conversion				$ 24,700,000
Shares related to convertible senior notes
Debt Instrument [Line Items]
Share price (in dollars per share) \| $ / shares					$ 90.33
Shares related to convertible senior notes \| 0% Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Face amount	$ 1,000,000,000.0				$ 1,000,000,000
Interest rate, stated percentage	0.00%
Principal amount	$ 1,000,000,000
Less initial purchasers’ discount	(15,000,000)
Less other issuance costs	(904,000)
Net proceeds	984,096,000
Debt instrument, equity component	241,300,000				237,462,000
Unamortized issuance costs	$ (15,900,000)				$ (11,338,000)
Conversion ratio	0.0092978
Conversion price \| $ / shares					$ 107.55
Debt instrument, remaining useful life					5 years 8 months 12 days
Debt conversion, converted instrument, amount					$ 839,900,000
Debt instrument, if-converted value less than principal					(160,100,000)
Interest rate, effective percentage	4.63%
Shares related to convertible senior notes \| 0% Convertible Senior Notes Due 2026 \| Debt Instrument, Liability Component
Debt Instrument [Line Items]
Carrying amount	$ 758,700,000
Unamortized issuance costs	(12,100,000)
Shares related to convertible senior notes \| 0% Convertible Senior Notes Due 2026 \| Debt Instrument, Equity Component
Debt Instrument [Line Items]
Unamortized issuance costs	(3,800,000)
Shares related to convertible senior notes \| 0% Convertible Senior Notes Due 2026, Additional Notes
Debt Instrument [Line Items]
Face amount	100,000,000
Shares related to convertible senior notes \| 0.125 Percent Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Face amount					800,000,000	800,000,000		$ 700,000,000
Interest rate, stated percentage								0.125%
Option to purchase additional notes		$ 100,000,000
Principal amount		800,000,000
Less initial purchasers’ discount		(18,998,000)
Less other issuance costs		(822,000)
Net proceeds		780,180,000
Debt instrument, equity component		212,000,000.0			206,747,000	206,747,000
Unamortized issuance costs		$ (19,800,000)			$ (10,248,000)	(12,691,000)
Conversion ratio		0.0193956
Conversion price \| $ / shares					$ 51.56
Debt instrument, remaining useful life					4 years 2 months 12 days
Debt conversion, converted instrument, amount					$ 1,401,600,000
Debt instrument, if-converted value in excess of principal					601,600,000
Interest rate, effective percentage		5.40%
Shares related to convertible senior notes \| 0.125 Percent Convertible Senior Notes Due 2025 \| Debt Instrument, Liability Component
Debt Instrument [Line Items]
Carrying amount		$ 588,000,000.0
Unamortized issuance costs		(14,600,000)
Shares related to convertible senior notes \| 0.125 Percent Convertible Senior Notes Due 2025 \| Debt Instrument, Equity Component
Debt Instrument [Line Items]
Unamortized issuance costs		(5,300,000)
Shares related to convertible senior notes \| 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Face amount			$ 345,000,000		115,576,000	345,000,000
Interest rate, stated percentage			0.25%
Option to purchase additional notes			$ 45,000,000
Principal amount			345,000,000
Less initial purchasers’ discount			(8,625,000)
Less other issuance costs			(757,000)
Net proceeds			335,618,000
Repurchased principal amount					57,400,000
Repayments of convertible senior notes					149,600,000
Carrying amount					115,600,000
Debt instrument, equity component			64,200,000		20,919,000	62,444,000
Unamortized issuance costs			$ (9,400,000)		$ (1,245,000)	$ (5,028,000)
Conversion ratio			0.0371051
Conversion price \| $ / shares					$ 26.95
Debt instrument, remaining useful life					2 years 4 months 24 days
Debt conversion, converted instrument, amount					$ 387,400,000
Debt instrument, if-converted value in excess of principal					271,800,000
Interest rate, effective percentage			4.34%
Shares related to convertible senior notes \| 0.25% Convertible Senior Notes Due 2023 \| Debt Instrument, Liability Component
Debt Instrument [Line Items]
Carrying amount			$ 280,800,000
Unamortized issuance costs			(7,600,000)
Shares related to convertible senior notes \| 0.25% Convertible Senior Notes Due 2023 \| Debt Instrument, Equity Component
Debt Instrument [Line Items]
Unamortized issuance costs			$ (1,700,000)
Sale Price Is Greater Or Equal 130% \| Shares related to convertible senior notes \| 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Threshold trading days \| day			20
Threshold consecutive trading days \| day			30
Threshold percentage of stock price trigger			130.00%
Trading Price Per $1,000 Principal Amount Less Than 98% \| Shares related to convertible senior notes \| 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Threshold trading days \| day			5
Threshold consecutive trading days \| day			10
Trading Price Per $1,000 Principal Amount Less Than 98% \| Shares related to convertible senior notes \| 0.25% Convertible Senior Notes Due 2023 \| Maximum
Debt Instrument [Line Items]
Threshold percentage of stock price trigger			98.00%
Exchange Of Aggregate Principal Amount \| Shares related to convertible senior notes \| 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Repurchased principal amount					172,000,000.0
Aggregate consideration for principal amount exchanged					501,700,000
Repayments of convertible senior notes					$ 174,600,000
Debt conversion, shares issued (in shares) \| shares					4,182,320
Debt conversion, shares issued, value					$ 327,100,000
Convertible senior notes					156,100,000
Carrying amount					152,800,000
Debt instrument, equity component					345,600,000
Loss on early extinguishments of debt					3,300,000
Extinguishment Of Aggregate Principal Amount \| Shares related to convertible senior notes \| 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Repurchased principal amount					57,400,000
Aggregate consideration for principal amount exchanged					149,600,000
Convertible senior notes					52,600,000
Carrying amount					51,600,000
Debt instrument, equity component					97,000,000.0
Loss on early extinguishments of debt					$ 1,000,000.0
Debt instrument, convertible, shares terminated (in shares) \| shares					2,131,354
Proceeds from exercise of convertible senior notes capped call					$ 19,700,000
Capped Call \| Shares related to convertible senior notes \| 0% Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Net proceeds	$ 103,400,000
Shares covered by capped call transactions (in shares) \| shares					9,297,800
Conversion price \| $ / shares					$ 156.44
Capped Call \| Shares related to convertible senior notes \| 0.125 Percent Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Net proceeds		$ 97,200,000
Shares covered by capped call transactions (in shares) \| shares					15,516,480
Conversion price \| $ / shares					$ 79.32
Capped Call \| Shares related to convertible senior notes \| 0.25% Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Net proceeds			$ 39,200,000
Debt instrument, convertible, shares terminated (in shares) \| shares					6,380,815
Proceeds from exercise of convertible senior notes capped call					$ 57,400,000
Shares covered by capped call transactions (in shares) \| shares					4,288,459
Conversion price \| $ / shares					$ 40.68