REVENUE - Metal Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue
Revenue	$ 118,774	$ 99,992
Stream interests
Disaggregation of Revenue
Revenue	86,981	70,037
Stream interests | Gold
Disaggregation of Revenue
Revenue	72,224	59,114
Stream interests | Silver
Disaggregation of Revenue
Revenue	8,436	8,720
Stream interests | Copper
Disaggregation of Revenue
Revenue	6,321	2,203
Royalty interests
Disaggregation of Revenue
Revenue	31,793	29,955
Royalty interests | Gold
Disaggregation of Revenue
Revenue	21,757	18,554
Royalty interests | Silver
Disaggregation of Revenue
Revenue	1,829	1,352
Royalty interests | Copper
Disaggregation of Revenue
Revenue	2,980	3,615
Royalty interests | Other
Disaggregation of Revenue
Revenue	$ 5,227	$ 6,434