Revenues (Net Profits on Inventory Sales Included in Commissions) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues [Abstract]
Revenue from inventory sales	$ 346,774	$ 571,134	$ 555,827
Cost of inventory sold	(306,498)	(513,348)	(511,892)
Net profits on inventory	$ 40,276	$ 57,786	$ 43,935

Aggregate commissions earned during the reporting period from sales of inventory at auctions where the Company acts as an agent, taking title of the inventory for a short period of time while rendering services in the normal course of business. The risks and rewards of ownership of the inventory are not substantially different from the risks and rewards associated with the Company's underwritten guarantee contracts.

No definition available.

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Namespace Prefix:	rba_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration