| Cover | Sep. 15, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Sep. 15, 2020 |
| Entity Registrant Name | Arbutus Biopharma Corp |
| Entity Incorporation, State or Country Code | A1 |
| Entity File Number | 001-34949 |
| Entity Tax Identification Number | 98-0597776 |
| Entity Address, Address Line One | 701 Veterans Circle |
| Entity Address, City or Town | Warminster |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 18974 |
| City Area Code | 267 |
| Local Phone Number | 469-0914 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Shares, without par value |
| Trading Symbol | ABUS |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001447028 |
| Document Information [Line Items] | |
| Document Period End Date | Sep. 15, 2020 |
