| Document and Entity Information | May 10, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | Domtar CORP |
| Entity Incorporation State Country Code | DE |
| Amendment Flag | false |
| Entity Central Index Key | 0001381531 |
| Document Type | 8-K |
| Document Period End Date | May 10, 2021 |
| Entity File Number | 001-33164 |
| Entity Tax Identification Number | 20-5901152 |
| Entity Address, Address Line One | 234 Kingsley Park Drive |
| Entity Address, City or Town | Fort Mill |
| Entity Address, State or Province | SC |
| Entity Address, Postal Zip Code | 29715 |
| City Area Code | (803) |
| Local Phone Number | 802-7500 |
| Written Communications | false |
| Soliciting Material | true |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
