| Cover Cover | Aug. 01, 2019 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Aug. 1, 2019 |
| Entity Registrant Name | WAYFAIR INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-36666 |
| Entity Tax Identification Number | 36-4791999 |
| Entity Address, Address Line One | 4 Copley Place |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02116 |
| City Area Code | 617 |
| Local Phone Number | 532-6100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A Common Stock, $0.001 par value per share |
| Trading Symbol | W |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001616707 |
| Amendment Flag | false |
