REVENUE (Details)	3 Months Ended
Sep. 30, 2018
Minimum
Average sale price determination period	10 days
Maximum
Average sale price determination period	3 months

Represents the period of consecutive trading days under the spot rate forward contract in which the sale price is determined on the daily average spot price.

No definition available.

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