Note 4 - Investment in the Joint Venture Company (Details Textual) - USD ($)	3 Months Ended		9 Months Ended		63 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2018	Apr. 26, 2018	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015	Jan. 08, 2015	Jun. 30, 2014
Equity Method Investments
The Joint Venture Company [Member]
Equity Method Investment, Aggregate Cost	$ 1,400,000		$ 1,400,000		1,400,000							$ 1,400,000
Payments to Acquire Interest in Joint Venture					11,400,000
Payments to Acquire Interest in Joint Venture					$ 10,000,000
Equity Method Investment, Ownership Percentage	60.00%		60.00%		60.00%			60.00%
Loss from Equity Method Investments, Unrecorded	$ 300,000	$ 200,000	$ 3,000,000	$ 3,500,000
Equity Method Investment, Summarized Financial Information, Inception-to-date Cumulative Income (Loss)	34,400,000		34,400,000		$ 34,400,000	31,500,000
Equity Method Investments	0		0		0	$ 0	$ 0		$ 0	$ 0	$ 0		$ 0
Equity Method Investment, Cumulative Investment	$ 11,400,000		11,400,000		11,400,000
Suspended Losses					23,000,000
The Joint Venture Company [Member] | Royal Gold [Member]
Payments to Acquire Interest in Joint Venture			$ 36,700,000		$ 36,700,000
Equity Method Investment, Ownership Percentage								40.00%