INCOME TAXES (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Income before income taxes
United States	$ (230)	$ 17,569	$ 17,033
Foreign	(21,528)	44,675	65,894
Income before income taxes	(21,758)	62,244	82,927
Current:
Federal	45,878	22,418	(3,663)
State	135	(36)	334
Foreign	19,650	14,835	30,950
Total current income tax expenses	65,663	37,217	27,621
Deferred and others:
Federal	(6,986)	(5,506)	(4,122)
State	(78)	(49)	(26)
Foreign	2,081	(22,096)	(4,018)
Total deferred and other income tax expenses	(4,983)	(27,651)	(8,166)
Total income tax expenses	60,680	9,566	19,455
Differences between provision for income taxes and income tax expense computed by applying federal rates
Total expense computed by applying federal rates	(7,615)	21,786	29,024
State and provincial income taxes, net of federal benefit	(1)	25	334
Excess depletion	(882)	(1,429)	(1,114)
Estimates for uncertain tax positions	1,866	1,404	(7,386)
Statutory tax attributable to non-controlling interest	1,838	(211)	(293)
Effect of foreign earnings	61,576	6,536	1,141
Effect of foreign earnings indefinitely reinvested	3,406	(7,601)	(1,700)
Unrealized foreign exchange gains	(2,439)	(10,949)	(367)
Changes in estimates	1,641	(359)	(594)
Other	1,290	(1,225)	410
Total income tax expenses	60,680	9,566	19,455
Deferred tax assets:
Stock-based compensation	5,691	4,393
Net operating losses	12,385	16,087
Other	4,610	3,904
Total deferred tax assets	22,686	24,384
Valuation allowance	(2,100)	(4,262)
Net deferred tax assets	20,586	20,122
Deferred tax liabilities:
Mineral property basis	(127,337)	(133,646)
Unrealized foreign exchange gains	(1,273)
Unrealized foreign exchange losses		936
2019 Notes	(12,639)	(16,384)
Other	(124)	(1,658)
Total deferred tax liabilities	(141,373)	(150,752)
Total net deferred taxes	(120,787)	(130,630)
Net operating loss carry forwards
Net operating loss carry forwards	59,500	55,000
Reconciliation of beginning and ending amount of gross unrecognized tax benefits
Total gross unrecognized tax benefits at beginning of year	15,130	13,725	21,166
Additions / Reductions for tax positions of current year	1,866	1,662	(1,052)
Reductions due to settlements with taxing authorities		(257)	(296)
Reductions due to lapse of statute of limitations			(6,093)
Total amount of gross unrecognized tax benefits at end of year	$ 16,996	15,130	$ 13,725
Net unrecognized tax benefits
Expiration period of statute of limitations for income tax examinations	12 months
Accrued income-tax-related interest and penalties	$ 5,700	4,600
Canada
Differences between provision for income taxes and income tax expense computed by applying federal rates
Income tax rate adjustment/ reform		4,070
Chile
Differences between provision for income taxes and income tax expense computed by applying federal rates
Income tax rate adjustment/ reform		$ (2,481)