STREAM AND ROYALTY INTERESTS, NET - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019
Cost	$ 3,402,360	$ 3,397,998
Accumulated Depletion	(1,097,342)	(1,058,682)
Net	2,305,018	2,339,316
Mount Milligan
Net	597,900
Total production stage stream and royalty interests
Cost	3,018,836	2,959,033
Accumulated Depletion	(1,097,342)	(1,058,682)
Net	1,921,494	1,900,351
Production stage stream interests
Cost	2,111,423	2,111,423
Accumulated Depletion	(532,488)	(501,026)
Net	1,578,935	1,610,397
Production stage stream interests | Mount Milligan
Cost	790,635	790,635
Accumulated Depletion	(192,726)	(184,091)
Net	597,909	606,544
Production stage stream interests | Pueblo Viejo
Cost	610,404	610,404
Accumulated Depletion	(168,961)	(158,819)
Net	441,443	451,585
Production stage stream interests | Andacollo
Cost	388,182	388,182
Accumulated Depletion	(93,774)	(86,675)
Net	294,408	301,507
Production stage stream interests | Rainy River
Cost	175,727	175,727
Accumulated Depletion	(17,462)	(14,522)
Net	158,265	161,205
Production stage stream interests | Wassa and Prestea
Cost	146,475	146,475
Accumulated Depletion	(59,565)	(56,919)
Net	86,910	89,556
Production stage royalty interests
Cost	907,413	847,610
Accumulated Depletion	(564,854)	(557,656)
Net	342,559	289,954
Production stage royalty interests | Voisey's Bay
Cost	205,724	205,724
Accumulated Depletion	(97,136)	(95,564)
Net	108,588	110,160
Production stage royalty interests | Penasquito
Cost	99,172	99,172
Accumulated Depletion	(41,414)	(40,659)
Net	57,758	58,513
Production stage royalty interests | Holt
Cost	34,612	34,612
Accumulated Depletion	(22,936)	(22,570)
Net	11,676	12,042
Production stage royalty interests | Cortez
Cost	80,681	20,878
Accumulated Depletion	(12,777)	(12,362)
Net	67,904	8,516
Production stage royalty interests | Other
Cost	487,224	487,224
Accumulated Depletion	(390,591)	(386,501)
Net	96,633	100,723
Total development stage stream and royalty interests
Cost	82,990	142,793
Net	82,990	142,793
Development stage stream interests | Other
Cost	12,038	12,038
Net	12,038	12,038
Development stage royalty interests
Cost		130,755
Net		130,755
Development stage royalty interests | Cortez
Cost		59,803
Net		59,803
Development stage royalty interests | Other
Cost	70,952	70,952
Net	70,952	70,952
Exploration stage royalty interests
Cost	300,534	296,172
Net	300,534	296,172
Exploration stage royalty interests | Pascua-Lama
Cost	177,690	177,690
Net	177,690	177,690
Exploration stage royalty interests | Other
Cost	122,844	118,482
Net	$ 122,844	$ 118,482