SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) segment	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Long Lived Assets and Pre-Tax Income by Geographical Information
Number of reportable segments | segment			2
Stream and royalty interest	$ 2,389,864		$ 2,389,864		$ 2,443,752
Revenue	146,441	$ 168,027	308,796	$ 310,616
Cost of sales	23,810	24,668	46,450	46,137
Production taxes	1,425	2,152	3,646	3,987
Depletion	43,865	47,936	91,730	89,138
Total segment gross profit	77,341	93,271	166,970	171,354
Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	955,262		955,262		991,745
Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	466,063		466,063		473,263
Dominican Republic
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	336,215		336,215		350,083
Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	314,028		314,028		297,890
United States
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	101,921		101,921		107,761
Mexico
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	55,877		55,877		60,977
Australia
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	26,861		26,861		27,496
Rest of world
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	133,637		133,637		134,537
Stream interests
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	1,539,655		1,539,655		1,584,045
Revenue	104,879	114,421	210,130	209,767
Cost of sales	23,810	24,668	46,450	46,137
Depletion	37,790	38,746	74,169	71,341
Total segment gross profit	43,279	51,007	89,511	92,289
Stream interests | Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	540,766		540,766		579,326
Revenue	54,591	52,040	106,077	94,649
Stream interests | Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	241,947		241,947		249,147
Revenue	11,721	27,868	27,395	40,889
Stream interests | Dominican Republic
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	336,215		336,215		350,083
Revenue	19,812	26,585	43,076	56,759
Stream interests | Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	313,707		313,707		297,569
Revenue	14,540	7,928	25,375	17,470
Stream interests | Rest of world
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	107,020		107,020		107,920
Revenue	4,215		8,207
Royalty interests
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	850,209		850,209		859,707
Revenue	41,562	53,606	98,666	100,849
Production taxes	1,425	2,152	3,646	3,987
Depletion	6,075	9,190	17,561	17,797
Total segment gross profit	34,062	42,264	77,459	79,065
Royalty interests | Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	414,496		414,496		412,419
Revenue	5,773	9,601	16,551	18,213
Royalty interests | Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	224,116		224,116		224,116
Royalty interests | Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	321		321		321
Revenue	114	559	430	1,307
Royalty interests | United States
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	101,921		101,921		107,761
Revenue	16,845	21,349	41,202	37,823
Royalty interests | Mexico
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	55,877		55,877		60,977
Revenue	11,940	16,191	27,821	31,461
Royalty interests | Australia
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	26,861		26,861		27,496
Revenue	4,040	4,249	8,086	8,610
Royalty interests | Rest of world
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	26,617		26,617		$ 26,617
Revenue	$ 2,850	$ 1,657	$ 4,576	$ 3,435