| Cover | Apr. 13, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Apr. 13, 2021 |
| Entity File Number | 001-13357 |
| Entity Registrant Name | ROYAL GOLD, INC. |
| Entity Central Index Key | 0000085535 |
| Entity Tax Identification Number | 84-0835164 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1144 15th Street |
| Entity Address, Address Line Two | Suite 2500 |
| Entity Address, City or Town | Denver |
| Entity Address, State or Province | CO |
| Entity Address, Postal Zip Code | 80202-2686 |
| City Area Code | 303 |
| Local Phone Number | 573-1660 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock $0.01 Par Value |
| Trading Symbol | RGLD |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
