| Cover Page - USD ($) $ in Billions | 12 Months Ended | | |
| Dec. 31, 2021 | Jun. 22, 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 | | | $ 9 |
| Entity Common Stock, Shares Outstanding | | 123,270,893 | |
| 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 “we”) filed its Annual Report on Form 10-K for the fiscal year ended December 31, 2021 (the “Original Filing”) with the U.S. Securities and Exchange Commission (the “SEC”) on February 15, 2022 and, on May 2, 2022, filed Amendment No. 1 to the Original Filing (“Amendment No. 1”) 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. Due to printer error, an incorrect version of Amendment No. 1 was filed, which omitted page 37 of Amendment No. 1 and duplicated page 38 of Amendment No.1. This Amendment No. 2 to the Original Filing is being filed solely to correct the printer error and to supplement Amendment No. 1 with the omitted page 37. Pursuant to Rule 12b-15 under the Exchange Act, the Company is including Item 15 of Part IV of this Amendment No. 2, 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 No. 2 and this Amendment No. 2 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. 2. Except as described above, this Amendment No. 2 does not amend any other information set forth in the Original Filing or Amendment No. 1, and we have not updated disclosures included therein to reflect any subsequent events. This Amendment No. 2 should be read in conjunction with the Original Filing, Amendment No. 1 and with our filings with the SEC subsequent to the Original Filing, including Amendment No. 1. | | |
