| Cover Page | Feb. 06, 2020 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Feb. 6, 2020 |
| Entity Registrant Name | ZENDESK, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-36456 |
| Entity Tax Identification Number | 26-4411091 |
| Entity Address, Address Line One | 1019 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | ZEN |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001463172 |
| Amendment Flag | false |
