SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($)	Mar. 31, 2022 USD ($) item	Mar. 31, 2022 USD ($) segment	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Long Lived Assets and Pre-Tax Income by Geographical Information
Number of reportable segments		2	2
Stream and royalty interest	$ 2,433,689	$ 2,433,689	$ 2,433,689		$ 2,443,752
Revenue	162,355			$ 142,589
Cost of sales	22,639			21,469
Production taxes	2,221			1,835
Depletion	47,863			41,202
Total segment gross profit	89,632			78,083
Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	976,816	976,816	976,816		991,745
Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	469,154	469,154	469,154		473,263
Dominican Republic
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	342,532	342,532	342,532		350,083
Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	320,148	320,148	320,148		297,890
United States
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	103,855	103,855	103,855		107,761
Mexico
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	58,276	58,276	58,276		60,977
Australia
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	27,193	27,193	27,193		27,496
Rest of world
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	135,715	135,715	135,715		134,537
Stream interests
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	1,577,406	1,577,406	1,577,406		1,584,045
Revenue	105,251			95,346
Cost of sales	22,639			21,469
Depletion	36,378			32,595
Total segment gross profit	46,234			41,282
Stream interests | Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	560,911	560,911	560,911		579,326
Revenue	51,485			42,609
Stream interests | Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	245,038	245,038	245,038		249,147
Revenue	15,674			13,022
Stream interests | Dominican Republic
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	342,532	342,532	342,532		350,083
Revenue	23,264			30,173
Stream interests | Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	319,827	319,827	319,827		297,569
Revenue	8,446			9,542
Stream interests | Rest of world
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	109,098	109,098	109,098		107,920
Revenue	6,382
Royalty interests
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	856,283	856,283	856,283		859,707
Revenue	57,104			47,243
Production taxes	2,221			1,835
Depletion	11,485			8,607
Total segment gross profit	43,398			36,801
Royalty interests | Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	415,905	415,905	415,905		412,419
Revenue	10,778			8,612
Royalty interests | Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	224,116	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		321
Revenue	316			748
Royalty interests | United States
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	103,855	103,855	103,855		107,761
Revenue	24,358			16,474
Royalty interests | Mexico
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	58,276	58,276	58,276		60,977
Revenue	15,881			15,270
Royalty interests | Australia
Long Lived Assets and Pre-Tax Income by Geographical Information
Stream and royalty interest	27,193	27,193	27,193		27,496
Revenue	4,046			4,360
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		$ 26,617
Revenue	$ 1,725			$ 1,779