| Cover Page - USD ($) $ in Billions | 12 Months Ended | | |
| Dec. 31, 2021 | Apr. 18, 2022 | Jun. 30, 2021 |
| Cover [Abstract] | | | |
| Document Type | 10-K/A | | |
| Document Annual Report | true | | |
| Document Period End Date | Dec. 31,
2021 | | |
| Current Fiscal Year End Date | --12-31 | | |
| Document Transition Report | false | | |
| Entity File Number | 1-6651 | | |
| Entity Registrant Name | Zendesk, Inc. | | |
| Entity Incorporation, State or Country Code | DE | | |
| Entity Tax Identification Number | 26-4411091 | | |
| Entity Address, Address Line One | 989 Market Street | | |
| Entity Address, City or Town | San Francisco | | |
| Entity Address, State or Province | CA | | |
| Entity Address, Postal Zip Code | 94103 | | |
| City Area Code | 415 | | |
| Local Phone Number | 418-7506 | | |
| Title of 12(b) Security | Common Stock, par value $0.01 per share | | |
| Trading Symbol | ZEN | | |
| Security Exchange Name | NYSE | | |
| Entity Well-known Seasoned Issuer | Yes | | |
| Entity Voluntary Filers | No | | |
| Entity Current Reporting Status | Yes | | |
| Entity Interactive Data Current | Yes | | |
| Entity Filer Category | Large Accelerated Filer | | |
| Smaller Reporting Company | false | | |
| Emerging Growth Company | false | | |
| ICFR Auditor Attestation Flag | true | | |
| Entity Shell Company | false | | |
| Entity Public Float | | | $ 12.4 |
| Entity Common Stock, Shares Outstanding | | 122,380,593 | |
| Amendment Flag | true | | |
| Document Fiscal Year Focus | 2021 | | |
| Document Fiscal Period Focus | FY | | |
| Entity Central Index Key | 0001463172 | | |
| Amendment Description | Zendesk, Inc. (“Zendesk”, the “Company”, the “Registrant” or “our”) is filing this Amendment No. 1 to Form 10-K on Form 10-K/A (this “Amendment”) to amend our Annual Report on Form 10-K for the fiscal year ended December 31, 2021 (the “Original Filing”), filed with the Securities and Exchange Commission (the “SEC”) on February 15, 2022. The purpose of this Amendment is solely to disclose the information required in Part III (Items 10, 11, 12, 13 and 14) of the Original Filing, which information was previously omitted from the Original Filing in reliance on General Instruction G(3) to Form 10-K, which permits the information in the above referenced items to be incorporated in the Form 10-K by reference from our definitive proxy statement if such statement is filed no later than 120 days after our fiscal year-end. We are filing this Amendment No. 1 to include Part III information in our Form 10-K because we will not file a definitive proxy statement containing such information within 120 days after the end of the fiscal year covered by the Original Filing. In addition, this Amendment deletes the reference on the cover of the Original Filing to the incorporation by reference of portions of our proxy statement into Part III of the Original Filing. In accordance with Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), Items 10 through 14 of Part III of the Original Filing are hereby deleted and restated in their entirety as set forth in the following Part III below. In addition, pursuant to Rule 12b-15 under the Exchange Act, the Company is including Item 15 of Part IV of this Amendment, solely to file the certifications required under Section 302 of the Sarbanes-Oxley Act of 2002. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4, and 5 of the certifications have been omitted. We are also not including the certifications under Section 906 of Sarbanes-Oxley Act of 2002 as no financial statements are being filed with this Amendment No. 1. Except as described above, this Amendment does not amend any other information set forth in the Original Filing, and we have not updated disclosures included therein to reflect any subsequent events. This Amendment should be read in conjunction with the Original Filing and with our filings with the SEC subsequent to the Original Filing. | | |
