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v3.20.4

Related Party Transactions - Schedule of related party (Detail) | 9 Months Ended
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Sep. 30, 2020
NetEase Group [Member] |
Related Party Transaction [Line Items] |
Relationships with the Group | Control or under common control

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- Definition This element represents a description of the nature of common ownership or management control relationships with other entities, regardless of there being transactions between the entities, when the existence of that control could result in operating results or financial position of the reporting entity significantly different from that which would have been obtained if the entities' were autonomous. + References No definition available. + Details
Name: | us-gaap_NatureOfCommonOwnershipOrManagementControlRelationships
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- 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_RelatedPartyTransactionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=dao_NetEaseGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |