STREAM AND ROYALTY INTERESTS, NET - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017
Cost	$ 3,624,500	$ 3,624,495
Accumulated Depletion	(771,902)	(732,239)
Net	2,852,598	2,892,256
Production stage stream interests
Cost	1,935,696	1,935,696
Accumulated Depletion	(275,645)	(243,595)
Net	1,660,051	1,692,101
Production stage stream interests | Mount Milligan
Cost	790,635	790,635
Accumulated Depletion	(123,427)	(114,327)
Net	667,208	676,308
Production stage stream interests | Pueblo Viejo
Cost	610,404	610,404
Accumulated Depletion	(79,801)	(67,149)
Net	530,603	543,255
Production stage stream interests | Andacollo
Cost	388,182	388,182
Accumulated Depletion	(43,722)	(39,404)
Net	344,460	348,778
Production stage stream interests | Wassa and Prestea
Cost	146,475	146,475
Accumulated Depletion	(28,695)	(22,715)
Net	117,780	123,760
Production stage royalty interests
Cost	844,029	844,024
Accumulated Depletion	(496,257)	(488,644)
Net	347,772	355,380
Production stage royalty interests | Voisey's Bay
Cost	205,724	205,724
Accumulated Depletion	(85,671)	(85,671)
Net	120,053	120,053
Production stage royalty interests | Penasquito
Cost	99,172	99,172
Accumulated Depletion	(35,882)	(34,713)
Net	63,290	64,459
Production stage royalty interests | Holt
Cost	34,612	34,612
Accumulated Depletion	(20,103)	(19,669)
Net	14,509	14,943
Production stage royalty interests | Cortez
Cost	20,878	20,873
Accumulated Depletion	(10,879)	(10,633)
Net	9,999	10,240
Production stage royalty interests | Other
Cost	483,643	483,643
Accumulated Depletion	(343,722)	(337,958)
Net	139,921	145,685
Total production stage stream and royalty interests
Cost	2,779,725	2,779,720
Accumulated Depletion	(771,902)	(732,239)
Net	2,007,823	2,047,481
Development stage stream interests
Cost	187,758	187,758
Net	187,758	187,758
Development stage stream interests | Rainy River
Cost	175,727	175,727
Net	175,727	175,727
Development stage stream interests | Other
Cost	12,031	12,031
Net	12,031	12,031
Development stage royalty interests
Cost	504,271	504,271
Net	504,271	504,271
Development stage royalty interests | Cortez
Cost	59,803	59,803
Net	59,803	59,803
Development stage royalty interests | Pascua-Lama
Cost	380,657	380,657
Net	380,657	380,657
Development stage royalty interests | Other
Cost	63,811	63,811
Net	63,811	63,811
Total development stage stream and royalty interests
Cost	692,029	692,029
Net	692,029	692,029
Exploration stage royalty interests
Cost	152,746	152,746
Net	$ 152,746	$ 152,746