Share-based payments (Narrative) (Details)	3 Months Ended	6 Months Ended
Dec. 31, 2020 USD ($)	Jun. 30, 2021 USD ($) D
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of trading days of volume weighted average price for fair value estimation \| D		20
Maximum employee contribution, percentage		4.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer matching contribution, percentage		50.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer matching contribution, percentage		100.00%
Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs		$ 8,979,000
Unrecognized compensation costs, period for recognition		2 years 4 months 24 days
Performance Share Unit Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market value of shares vested and released	$ 0	$ 0
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs		$ 14,431,000
Unrecognized compensation costs, period for recognition		2 years 1 month 6 days
Restricted Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs		$ 2,323,000
Unrecognized compensation costs, period for recognition		1 year 7 months 6 days
Number of trading days of volume weighted average price for fair value estimation \| D		20
Deferred Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs		$ 0
Share unit liability	$ 9,597,000	$ 8,699,000

Employee Stock Purchase Plan, Employer Matching Contribution, Percent of Match

No definition available.

Name:	rba_EmployeeStockPurchasePlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix:	rba_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee Stock Purchase Plan, Maximum Annual Contributions Per Employee, Percent

+ References

No definition available.

+ Details

Name:	rba_EmployeeStockPurchasePlanMaximumAnnualContributionsPerEmployeePercent
Namespace Prefix:	rba_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of specified trading days for weighted average price of the Company's common shares listed on the New York Stock Exchange to estimate the fair values on grant date and at each reporting date.

+ References

No definition available.

+ Details

Name:	rba_FairValueWeightedAveragePriceTradingDays
Namespace Prefix:	rba_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. Additionally, share-based awards which were paid or settled.

+ References

No definition available.

+ Details

Name:	rba_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndSettledInPeriodFairValue
Namespace Prefix:	rba_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Intrinsic value of outstanding award under share-based payment arrangement. Excludes share and unit options.

+ References

No definition available.

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=rba_StockOptionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=rba_PerformanceShareUnitPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=rba_DeferredShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: