SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2017 USD ($) segment	Mar. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)
Long Lived Assets and Pre-Tax Income by Geographical Information
Number of reportable segments | segment			2
Revenue	$ 106,972	$ 93,487	$ 331,880	$ 265,660
Cost of sales	22,419	17,921	67,582	51,960
Net revenue	84,553	75,566	264,298	213,700
Total stream and royalty interests, net	2,932,087		2,932,087		$ 2,848,087
Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	1,084,688		1,084,688		1,038,258
Dominican Republic
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	553,149		553,149		588,502
Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	808,888		808,888		823,525
Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	129,727		129,727		89,293
Mexico
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	109,017		109,017		118,899
United States
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	169,127		169,127		102,385
Australia
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	38,623		38,623		42,547
Other
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	38,868		38,868		44,678
Stream interest
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	76,597	63,439	236,108	168,607
Cost of sales	22,419	17,921	67,582	51,960
Net revenue	54,178	45,518	168,526	116,647
Total stream and royalty interests, net	1,911,322		1,911,322		1,868,715
Stream interest | Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	35,112	29,946	105,161	95,881
Cost of sales	12,583	11,095	36,341	37,084
Net revenue	22,529	18,851	68,820	58,797
Total stream and royalty interests, net	861,592		861,592		809,692
Stream interest | Dominican Republic
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	24,524	13,608	71,911	23,008
Cost of sales	7,054	3,787	21,497	6,619
Net revenue	17,470	9,821	50,414	16,389
Total stream and royalty interests, net	553,149		553,149		588,502
Stream interest | Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	10,398	15,730	41,552	32,163
Cost of sales	1,499	2,255	6,243	4,751
Net revenue	8,899	13,475	35,309	27,412
Total stream and royalty interests, net	355,429		355,429		369,896
Stream interest | Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	6,563	4,155	17,484	17,555
Cost of sales	1,283	784	3,501	3,506
Net revenue	5,280	3,371	13,983	14,049
Total stream and royalty interests, net	129,121		129,121		88,596
Stream interest | Other
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	12,031		12,031		12,029
Royalty interest
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	30,375	30,048	95,772	97,053
Net revenue	30,375	30,048	95,772	97,053
Total stream and royalty interests, net	1,020,765		1,020,765		979,372
Royalty interest | Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	5,535	8,029	17,405	25,635
Net revenue	5,535	8,029	17,405	25,635
Total stream and royalty interests, net	223,096		223,096		228,566
Royalty interest | Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue			1,333
Net revenue			1,333
Total stream and royalty interests, net	453,459		453,459		453,629
Royalty interest | Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	672	570	2,260	1,301
Net revenue	672	570	2,260	1,301
Total stream and royalty interests, net	606		606		697
Royalty interest | Mexico
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	10,446	8,353	31,573	29,446
Net revenue	10,446	8,353	31,573	29,446
Total stream and royalty interests, net	109,017		109,017		118,899
Royalty interest | United States
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	7,899	8,522	27,012	27,220
Net revenue	7,899	8,522	27,012	27,220
Total stream and royalty interests, net	169,127		169,127		102,385
Royalty interest | Australia
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	3,174	2,834	9,867	7,610
Net revenue	3,174	2,834	9,867	7,610
Total stream and royalty interests, net	38,623		38,623		42,547
Royalty interest | Other
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	2,649	1,740	6,322	5,841
Net revenue	2,649	$ 1,740	6,322	$ 5,841
Total stream and royalty interests, net	$ 26,837		$ 26,837		$ 32,649