| Document and Entity Information Document | Oct. 28, 2019 |
| Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 28, 2019 |
| Entity Registrant Name | Sotheby's |
| Entity Central Index Key | 0000823094 |
| Amendment Flag | false |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-9750 |
| Entity Tax Identification Number | 38-2478409 |
| Entity Address, Address Line One | 1334 York Avenue |
| Entity Address, City or Town | New York, |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10021 |
| City Area Code | 212 |
| Local Phone Number | 606-7000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, $0.01 par value |
| Trading Symbol | BID |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
