STREAM AND ROYALTY INTERESTS, NET (Details) $ in Thousands	9 Months Ended
	Mar. 31, 2020 USD ($) oz $ / oz $ / lb	Jun. 30, 2019 USD ($)
Stream and royalty interests, net | $	$ 2,317,413	$ 2,339,316
Mount Milligan
Gold streaming interest (as a percent)	35.00%
Copper streaming interest (as a percent)	18.75%
Stream and royalty interests, net | $	$ 572,300
Mount Milligan | Gold
Depletion rate | $ / oz	764
Mount Milligan | Copper
Depletion rate | $ / lb	1.48
Rainy River
Stream and royalty interests, net | $	$ 152,600
Gold delivered (in ounces) | oz	35,700
Silver delivered (in ounces) | oz	373,100
Rainy River | Initial Royalty
Gold streaming interest (as a percent)	6.50%
Silver production acquired (as a percent)	60.00%
Gold delivered (in ounces) | oz	230,000
Silver delivered (in ounces) | oz	3,100,000
Rainy River | Subsequent Royalty
Gold streaming interest (as a percent)	3.25%
Silver production acquired (as a percent)	30.00%
Rainy River | Gold
Depletion rate | $ / oz	848
Rainy River | Silver
Depletion rate | $ / oz	11.27
El Toqui
Stream and royalty interests, net | $	$ 1,300