Revenue recognition - Deferred Contracts Costs Rollforward (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021
Deferred contract costs [Roll Forward]
Balance at Beginning of Period	$ 44,545	$ 25,837
Additions	40,203	25,455
Amortization Expense	(22,558)	(11,995)
Balance at End of Period	$ 62,190	$ 39,297

Capitalized Contract Cost, Amount Capitalized During the Period

No definition available.

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Namespace Prefix:	udmy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Capitalized Contract Cost

+ References

No definition available.

+ Details

Name:	udmy_CapitalizedContractCostRollForward
Namespace Prefix:	udmy_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126905575&loc=SL49131252-203054

+ Details

Name:	us-gaap_CapitalizedContractCostAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126905575&loc=SL49131252-203054

+ Details

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