| Document and Entity Information | Dec. 17, 2021 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001808898 |
| Current Fiscal Year End Date | --06-30 |
| Document Type | 8-K |
| Document Period End Date | Dec. 17, 2021 |
| Entity Registrant Name | BENITEC BIOPHARMA INC. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-39267 |
| Entity Tax Identification Number | 84-4620206 |
| Entity Address, Address Line One | 3940 Trust Way |
| Entity Address, City or Town | Hayward |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94545 |
| City Area Code | (510) |
| Local Phone Number | 780-0819 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $0.0001 |
| Trading Symbol | BNTC |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
