Business Combinations (Schedule of Assets Acquired and Liabilities Assumed) (Details) € in Thousands, CAD in Thousands, $ in Thousands									12 Months Ended
		May 31, 2017 USD ($)	Nov. 15, 2016 CAD	Nov. 15, 2016 USD ($)	Aug. 01, 2016 USD ($)	May 27, 2016 USD ($)	Feb. 19, 2016 EUR (€) item	Feb. 19, 2016 USD ($) item	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Goodwill acquired on acquisition									$ 670,922	$ 97,537	$ 91,234
Acquisition of NCI										$ 226
Iron Planet Holdings Inc. [Member]
Business Acquisition [Line Items]
Purchase price		$ 772,706
Total fair value at acquisition date		776,474
Cash and cash equivalents		95,626
Restricted cash		3,000
Trade and other receivables		13,021
Inventory		600
Advances against auction contracts		4,623
Prepaid expenses		1,645
Income taxes receivable		55
Property, plant and equipment		2,381
Other non-current assets		2,551
Deferred tax assets		1,497
Intangible assets	[1]	188,000
Auction proceeds payable		63,616
Trade and other payables		14,511
Deferred tax liabilities		26,959
Fair value of identifiable net assets acquired		207,913
Goodwill acquired on acquisition		$ 568,561
Iron Planet Holdings Inc. [Member] | Technology [Member]
Business Acquisition [Line Items]
Amortization life		7 years
Mascus International Holdings BV [Member]
Business Acquisition [Line Items]
Purchase price							€ 26,553	$ 29,580
Fair value of contingent consideration								3,431
Non-controlling interests	[2]							596
Total fair value at acquisition date								33,607
Cash and cash equivalents								1,457
Trade and other receivables								1,290
Prepaid expenses								528
Property, plant and equipment								104
Intangible assets	[3]							14,817
Trade and other payables								1,533
Other non-current liabilities								37
Deferred tax liabilities								2,683
Fair value of identifiable net assets acquired								13,943
Goodwill acquired on acquisition								$ 19,664
Number of not wholly owned subsidiaries acquried | item							2	2
Mascus International Holdings BV [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Amortization life									17 years
Mascus International Holdings BV [Member] | Software Assets [Member]
Business Acquisition [Line Items]
Amortization life									5 years
Mascus International Holdings BV [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Amortization life									5 years
Mascus Subsidiary [Member]
Business Acquisition [Line Items]
Acquisition of NCI						$ 226
Petrowsky Auctioneers Inc. [Member]
Business Acquisition [Line Items]
Purchase price					$ 6,250
Fair value of contingent consideration					1,433
Total fair value at acquisition date					7,683
Property, plant and equipment					441
Intangible assets	[4]				2,934
Fair value of identifiable net assets acquired					3,375
Goodwill acquired on acquisition					$ 4,308
Petrowsky Auctioneers Inc. [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Amortization life					10 years
Kramer Auctions Ltd. [Member]
Business Acquisition [Line Items]
Purchase price			CAD 15,000	$ 11,138
Deferred purchase note consideration			CAD 300	223
Fair value of contingent consideration				538
Total fair value at acquisition date				11,899
Property, plant and equipment				399
Intangible assets	[5]			4,678
Fair value of identifiable net assets acquired				5,077
Goodwill acquired on acquisition				$ 6,822
Kramer Auctions Ltd. [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Amortization life									10 years
Kramer Auctions Ltd. [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Amortization life									3 years
Minimum [Member] | Iron Planet Holdings Inc. [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Amortization life		6 years
Maximum [Member] | Iron Planet Holdings Inc. [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Amortization life		13 years

[1] Intangible assets consist of indefinite-lived trade names and trademarks, customer relationships with estimated useful lives of ranging from six to 13 years, and a technology platform with an estimated useful life of 7 years.

[2] The Company acquired 100% of Mascus and within the Mascus group of entities there were two subsidiaries that were not wholly-owned, one domiciled in the United States and one domiciled in Denmark. As such, the Company acquired non-controlling interests. The fair value of each non-controlling interest was determined using an income approach based on cash flows of the respective entities that were attributable to the non-controlling interest. On May 27, 2016, Ritchie Bros. Holdings (America) Inc. acquired the remaining issued and outstanding shares of the Mascus subsidiary domiciled in the United States for cash consideration of $226,000.

[3] Intangible assets consist of customer relationships with estimated useful lives of 17 years, indefinite-lived trade names, and software assets with estimated useful lives of five years.

[4] Consists of customer relationships with estimated useful lives of 10 years.

[5] Consists of customer relationships and trade names with estimated useful lives of 10 and three years, respectively.