STREAM AND ROYALTY INTERESTS, NET - Summary (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2018	Mar. 31, 2018	Jun. 30, 2017
Cost	$ 3,625,506	$ 3,625,506	$ 3,624,495
Accumulated Depletion	(853,539)	(853,539)	(732,239)
Impairments	(239,364)	(239,364)
Net	2,532,603	2,532,603	2,892,256
Impairment of royalty interests	239,364	239,364
Production stage stream interests
Cost	2,111,423	2,111,423	1,935,696
Accumulated Depletion	(340,216)	(340,216)	(243,595)
Net	1,771,207	1,771,207	1,692,101
Production stage stream interests | Mount Milligan
Cost	790,635	790,635	790,635
Accumulated Depletion	(143,370)	(143,370)	(114,327)
Net	647,265	647,265	676,308
Production stage stream interests | Pueblo Viejo
Cost	610,404	610,404	610,404
Accumulated Depletion	(101,193)	(101,193)	(67,149)
Net	509,211	509,211	543,255
Production stage stream interests | Andacollo
Cost	388,182	388,182	388,182
Accumulated Depletion	(53,916)	(53,916)	(39,404)
Net	334,266	334,266	348,778
Production stage stream interests | Wassa and Prestea
Cost	146,475	146,475	146,475
Accumulated Depletion	(39,383)	(39,383)	(22,715)
Net	107,092	107,092	123,760
Production stage stream interests | Rainy River
Cost	175,727	175,727
Accumulated Depletion	(2,354)	(2,354)
Net	173,373	173,373
Production stage royalty interests
Cost	844,181	844,181	844,024
Accumulated Depletion	(513,323)	(513,323)	(488,644)
Net	330,858	330,858	355,380
Production stage royalty interests | Voisey's Bay
Cost	205,724	205,724	205,724
Accumulated Depletion	(85,671)	(85,671)	(85,671)
Net	120,053	120,053	120,053
Production stage royalty interests | Penasquito
Cost	99,172	99,172	99,172
Accumulated Depletion	(37,636)	(37,636)	(34,713)
Net	61,536	61,536	64,459
Production stage royalty interests | Holt
Cost	34,612	34,612	34,612
Accumulated Depletion	(20,868)	(20,868)	(19,669)
Net	13,744	13,744	14,943
Production stage royalty interests | Cortez
Cost	20,878	20,878	20,873
Accumulated Depletion	(11,230)	(11,230)	(10,633)
Net	9,648	9,648	10,240
Production stage royalty interests | Other
Cost	483,795	483,795	483,643
Accumulated Depletion	(357,918)	(357,918)	(337,958)
Net	125,877	125,877	145,685
Total production stage stream and royalty interests
Cost	2,955,604	2,955,604	2,779,720
Accumulated Depletion	(853,539)	(853,539)	(732,239)
Net	2,102,065	2,102,065	2,047,481
Development stage stream interests
Cost			187,758
Net			187,758
Development stage stream interests | Rainy River
Cost			175,727
Net			175,727
Development stage stream interests | Other
Cost	12,038	12,038	12,031
Net	12,038	12,038	12,031
Development stage royalty interests
Cost	123,613	123,613	123,614
Impairments	(284)	(284)
Net	123,329	123,329	123,614
Development stage royalty interests | Cortez
Cost	59,803	59,803	59,803
Net	59,803	59,803	59,803
Development stage royalty interests | Other
Cost	63,810	63,810	63,811
Impairments	(284)	(284)
Net	63,526	63,526	63,811
Total development stage stream and royalty interests
Cost	135,651	135,651	311,372
Impairments	(284)	(284)
Net	135,367	135,367	311,372
Exploration stage royalty interests
Cost	534,251	534,251	533,403
Impairments	(239,080)	(239,080)
Net	295,171	295,171	533,403
Exploration stage royalty interests | Pascua-Lama
Cost	416,770	416,770	416,770
Impairments	(239,080)	(239,080)
Net	177,690	177,690	416,770
Exploration stage royalty interests | Other
Cost	117,481	117,481	116,633
Net	$ 117,481	$ 117,481	$ 116,633