STREAM AND ROYALTY INTERESTS, NET - Summary (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2016	Dec. 30, 2015	Sep. 30, 2014
Cost	$ 3,624,495	$ 3,551,575
Accumulated Depletion	(732,239)	(607,370)
Impairments		(96,118)
Net	2,892,256	2,848,087
Wassa and Prestea
Cost				$ 145,000
Other
Net			$ 0		$ 0
Production stage stream interests
Cost	1,935,696	1,878,045
Accumulated Depletion	(243,595)	(122,064)
Net	1,692,101	1,755,981
Production stage stream interests | Mount Milligan
Cost	790,635	783,046
Accumulated Depletion	(114,327)	(74,060)
Net	676,308	708,986
Production stage stream interests | Pueblo Viejo
Cost	610,404	610,404
Accumulated Depletion	(67,149)	(21,902)
Net	543,255	588,502
Production stage stream interests | Andacollo
Cost	388,182
Accumulated Depletion	(39,404)
Net	348,778
Production stage stream interests | Wassa and Prestea
Cost	146,475	96,413
Accumulated Depletion	(22,715)	(7,816)
Net	123,760	88,597
Production stage royalty interests
Cost	844,024	881,873
Accumulated Depletion	(488,644)	(485,153)
Impairments		(18,605)
Net	355,380	378,115
Production stage royalty interests | Andacollo
Cost		388,182
Accumulated Depletion		(18,286)
Net		369,896
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	(34,713)	(29,898)
Net	64,459	69,274
Production stage royalty interests | Holt
Cost	34,612	34,612
Accumulated Depletion	(19,669)	(17,124)
Net	14,943	17,488
Production stage royalty interests | Cortez
Cost	20,873	10,630
Accumulated Depletion	(10,633)	(10,000)
Net	10,240	630
Production stage royalty interests | Other
Cost	483,643	531,735
Accumulated Depletion	(337,958)	(342,460)
Impairments		(18,605)
Net	145,685	170,670
Total production stage stream and royalty interests
Cost	2,779,720	2,759,918
Accumulated Depletion	(732,239)	(607,217)
Impairments		(18,605)
Net	2,047,481	2,134,096
Development stage stream interests
Cost	187,758	188,589
Accumulated Depletion		(153)
Impairments		(75,702)
Net	187,758	112,734
Development stage stream interests | Rainy River
Cost	175,727	100,706
Net	175,727	100,706
Development stage stream interests | Other
Cost	12,031	87,883
Accumulated Depletion		(153)
Impairments		(75,702)
Net	12,031	12,028
Development stage royalty interests
Cost	504,271	447,071
Net	504,271	447,071
Development stage royalty interests | Cortez
Cost	59,803
Net	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	66,414
Net	63,811	66,414
Total development stage stream and royalty interests
Cost	692,029	635,660
Accumulated Depletion		(153)
Impairments		(75,702)
Net	692,029	559,805
Exploration stage royalty interests
Cost	152,746	155,997
Impairments		(1,811)
Net	$ 152,746	$ 154,186