SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)
Long Lived Assets and Pre-Tax Income by Geographical Information
Number of reportable segments | segment			2
Revenue	$ 106,961	$ 98,118	$ 224,909	$ 172,173
Cost of sales	22,502	22,572	45,163	34,038
Net revenue	84,459	75,546	179,746	138,135
Total stream and royalty interests, net	2,961,328		2,961,328		$ 2,848,087
Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	1,096,912		1,096,912		1,038,258
Mexico
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	112,020		112,020		118,899
United States
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	169,018		169,018		102,385
Australia
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	39,789		39,789		42,547
Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	812,728		812,728		823,525
Dominican Republic
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	565,799		565,799		588,502
Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	124,324		124,324		89,293
Other
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	40,738		40,738		44,678
Stream interest
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	74,007	67,312	159,511	105,168
Cost of sales	22,502	22,572	45,163	34,038
Net revenue	51,505	44,740	114,348	71,130
Total stream and royalty interests, net	1,933,079		1,933,079		1,868,715
Stream interest | Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	31,664	42,418	70,050	65,935
Cost of sales	11,181	16,860	23,758	25,988
Net revenue	20,483	25,558	46,292	39,947
Total stream and royalty interests, net	872,322		872,322		809,692
Stream interest | Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	10,985	5,718	31,154	16,433
Cost of sales	1,746	892	4,744	2,496
Net revenue	9,239	4,826	26,410	13,937
Total stream and royalty interests, net	359,236		359,236		369,896
Stream interest | Dominican Republic
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	26,437	9,400	47,387	9,400
Cost of sales	8,547	2,832	14,443	2,832
Net revenue	17,890	6,568	32,944	6,568
Total stream and royalty interests, net	565,799		565,799		588,502
Stream interest | Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	4,921	9,776	10,920	13,400
Cost of sales	1,028	1,988	2,218	2,722
Net revenue	3,893	7,788	8,702	10,678
Total stream and royalty interests, net	123,690		123,690		88,596
Stream interest | Other
Long Lived Assets and Pre-Tax Income by Geographical Information
Total stream and royalty interests, net	12,032		12,032		12,029
Royalty interest
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	32,954	30,806	65,398	67,005
Net revenue	32,954	30,806	65,398	67,005
Total stream and royalty interests, net	1,028,249		1,028,249		979,372
Royalty interest | Canada
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	5,682	7,206	11,870	17,607
Net revenue	5,682	7,206	11,870	17,607
Total stream and royalty interests, net	224,590		224,590		228,566
Royalty interest | Mexico
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	11,530	10,287	21,127	21,092
Net revenue	11,530	10,287	21,127	21,092
Total stream and royalty interests, net	112,020		112,020		118,899
Royalty interest | United States
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	9,407	8,484	19,113	18,697
Net revenue	9,407	8,484	19,113	18,697
Total stream and royalty interests, net	169,018		169,018		102,385
Royalty interest | Australia
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	3,230	2,325	6,692	4,776
Net revenue	3,230	2,325	6,692	4,776
Total stream and royalty interests, net	39,789		39,789		42,547
Royalty interest | Chile
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue			950
Net revenue			950
Total stream and royalty interests, net	453,492		453,492		453,629
Royalty interest | Africa
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	764	474	1,588	731
Net revenue	764	474	1,588	731
Total stream and royalty interests, net	634		634		697
Royalty interest | Other
Long Lived Assets and Pre-Tax Income by Geographical Information
Revenue	2,341	2,030	4,058	4,102
Net revenue	2,341	$ 2,030	4,058	$ 4,102
Total stream and royalty interests, net	$ 28,706		$ 28,706		$ 32,649