SEGMENT INFORMATION - Reconciliation gross profit (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
SEGMENT INFORMATION
Total segment gross profit	$ 84,239	$ 61,600	$ 161,649	$ 120,503
Costs and expenses
General and administrative expenses	6,789	6,665	14,244	14,108
Exploration costs		1,514	563	4,140
Depreciation and amortization	84	114	170	167
Gain on sale of Peak Gold JV interest			(33,906)
Operating income	77,366	53,307	180,578	102,088
Fair value changes in equity securities	(382)	222	2,158	(1,153)
Interest and other income	613	226	1,034	1,001
Interest and other expense	(1,578)	(2,217)	(3,454)	(5,051)
Income before income taxes	$ 76,019	$ 51,538	$ 180,316	$ 96,885