ACQUISITIONS - Khoemacau (Details) oz in Millions, $ in Millions	Feb. 25, 2019 USD ($) t oz	Jun. 30, 2019 USD ($)
Acquisitions
Maximum future additional payments upon satisfaction of certain conditions	$ 212.0
Option contribution amount	$ 53.0
Throughput levels \| t	13,000
Khoemacau
Acquisitions
Maximum future additional payments upon satisfaction of certain conditions	$ 212.0	$ 212.0
Silver production acquired (as a percent)	80.00%
Option contribution amount	$ 53.0
Silver production option (as a percent)	20.00%
Rate reduction (as a percent)	50.00%
Silver production after threshold (as a percent)	40.00%
Rate reduction threshold \| oz	32
Rate reduction threshold with option \| oz	40
Spot price paid (as a percent)	20.00%
Increased level of throughput (as a percent)	30.00%
Cupric required initial investment	$ 100.0
Contributions payable in 2019	60.0
Contributions payable in 2020	125.0
Loan receivable commitment	$ 25.0
Loan receivable term	7 years
Khoemacau \| LIBOR
Acquisitions
Loans receivable variable interest rate (as a percent)	11.00%

Option contribution amount pursuant to the agreement for additional ownership.

No definition available.

Name:	rgld_AcquisitionOptionContributionAmount
Namespace Prefix:	rgld_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The counterparty's required initial investment prior to entity investing.

+ References

No definition available.

+ Details

Name:	rgld_CounterpartyRequiredInitialInvestment
Namespace Prefix:	rgld_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the term of the loan receivable.

+ References

No definition available.

+ Details

Name:	rgld_LoansReceivableTerm
Namespace Prefix:	rgld_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The increased level of throughput, as a percent, which will increase the spot price paid percentage.

+ References

No definition available.

+ Details

Name:	rgld_PercentageOfSpotPriceIncreasedThroughputLevel
Namespace Prefix:	rgld_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of spot price paid.

+ References

No definition available.

+ Details

Name:	rgld_PercentageOfSpotPricePaidCurrentLevel
Namespace Prefix:	rgld_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of silver production to be received after achieving the threshold.

+ References

No definition available.

+ Details

Name:	rgld_SilverProductionAfterThresholdPercentage
Namespace Prefix:	rgld_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The option percentage of silver production that can be acquired.

+ References

No definition available.

+ Details

Name:	rgld_SilverProductionOptionPercentage
Namespace Prefix:	rgld_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of silver production initially acquired.

+ References

No definition available.

+ Details

Name:	rgld_SilverProductionPercentage
Namespace Prefix:	rgld_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage rate reduction percentage of silver production received upon agreement threshold.

+ References

No definition available.

+ Details

Name:	rgld_SilverProductionReductionPercentage
Namespace Prefix:	rgld_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The threshold per agreement upon which there is a rate reduction percentage of silver production received with the option exercised.

+ References

No definition available.

+ Details

Name:	rgld_SilverProductionReductionRateOptionThreshold
Namespace Prefix:	rgld_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	instant

- Definition

The threshold per agreement upon which there is a rate reduction percentage of silver production received.

+ References

No definition available.

+ Details

Name:	rgld_SilverProductionReductionRateThreshold
Namespace Prefix:	rgld_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	instant

- Definition

The increased level of throughput as a threshold.

+ References

No definition available.

+ Details

Name:	rgld_ThroughputLevels
Namespace Prefix:	rgld_
Data Type:	num:massItemType
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_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

+ Details

Name:	us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the amount of cash required to fully fund agreements to provide advances to borrowers and lessees at interest rates that increase or decrease depending on certain facts or circumstances.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=108315417&loc=d3e61082-112788

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=108315417&loc=d3e61044-112788

+ Details

Name:	us-gaap_LoansAndLeasesReceivableCommitmentsVariableRates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The percentage points (also referred to as 'margin') added to the reference rate as stated in the loan agreement and used to compute the variable rate on the loans receivable. For instance, the loan agreement might state that the interest rate the borrower is obligated to pay is the London Interbank Offered Rate (LIBOR) plus three quarters (3/4) of a percentage point adjusted quarterly (each three months). LIBOR in this example is the index or reference rate, 3/4 percentage point is the margin, the reference rate plus the margin is the fully indexed rate. This element would be used to report separately the margin.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansReceivableBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Minimum amount of other commitment maturing in the next fiscal year following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherCommitmentDueInNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Minimum amount of other commitment maturing in the second fiscal year following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherCommitmentDueInSecondYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=rgld_KhoemacauCopperProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: