Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 08, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	Ritchie Bros Auctioneers Inc
Entity Central Index Key	0001046102
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Trading Symbol	rba
Entity Common Stock, Shares Outstanding		108,984,083
Entity Emerging Growth Company	false
Entity Small Business	false