REVENUE - Property Disaggregation (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue
Revenue	$ 342,952	$ 305,240	$ 615,856	$ 498,819	$ 423,056
Stream interests
Disaggregation of Revenue
Revenue	226,551		423,989	359,868	305,824
Stream interests | Mt. Milligan
Disaggregation of Revenue
Revenue	95,509		156,938	131,425	101,010
Stream interests | Pueblo Viejo
Disaggregation of Revenue
Revenue	52,958		115,583	96,978	82,844
Stream interests | Andacollo
Disaggregation of Revenue
Revenue	28,076		82,164	74,219	69,264
Stream interests | Wassa
Disaggregation of Revenue
Revenue	15,691		31,772	23,203	22,098
Stream interests | Khoemacau
Disaggregation of Revenue
Revenue	5,096
Stream interests | Other Mines
Disaggregation of Revenue
Revenue	29,221		37,532	34,043	30,608
Royalty interests
Disaggregation of Revenue
Revenue	116,401		191,867	138,951	117,232
Royalty interests | Cortez
Disaggregation of Revenue
Revenue	33,768		36,160	22,342	11,383
Royalty interests | Penasquito
Disaggregation of Revenue
Revenue	26,432		49,688	25,498	13,865
Royalty interests | Other Mines
Disaggregation of Revenue
Revenue	$ 56,201		$ 106,019	$ 91,111	$ 91,984