| Cover | Nov. 07, 2019 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 7, 2019 |
| Entity File Number | 001-13425 |
| Entity Registrant Name | Ritchie Bros. Auctioneers Incorporated |
| Entity Central Index Key | 0001046102 |
| Entity Tax Identification Number | 98-0626225 |
| Entity Incorporation, State or Country Code | Z4 |
| Entity Address, Address Line One | 9500 Glenlyon Parkway |
| Entity Address, City or Town | Burnaby |
| Entity Address, State or Province | BC |
| Entity Address, Country | CA |
| Entity Address, Postal Zip Code | V5J0C6 |
| City Area Code | 778 |
| Local Phone Number | 331-5500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common shares |
| Trading Symbol | RBA |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
