OPERATIONS, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENTLY ADOPTED AND RECENTLY ISSUED ACCOUNTING STANDARDS (Details)	3 Months Ended
Sep. 30, 2018 item
OPERATIONS, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENTLY ADOPTED AND RECENTLY ISSUED ACCOUNTING STANDARDS
Minimum number of metals produced from a mine	1

Represents the minimum number of metals produced from a mine of which the right to purchase all or a portion is available in exchange for upfront deposit.

No definition available.

Name:	rgld_MinimumNumberOfMetalsProducedFromMineOfWhichRightToPurchaseInAllOrPortionAvailableInExchangeForUpfrontDeposit
Namespace Prefix:	rgld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration