INCOME TAXES (Details) (USD $)	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011 M	Jun. 30, 2010
Income before income taxes
United States	$ 110,189,000	$ 77,543,000	$ 55,623,000
Foreign	42,830,000	38,730,000	(12,037,000)
Income before income taxes	153,019,000	116,273,000	43,586,000
Current:
Federal	35,556,000	28,783,000	20,299,000
State	310,000	105,000	219,000
Foreign	17,273,000	15,222,000	1,182,000
Total current income tax expenses	53,139,000	44,110,000	21,700,000
Deferred and others:
Federal	77,000	(1,242,000)	(1,304,000)
State			(114,000)
Foreign	1,494,000	(3,894,000)	(6,118,000)
Total deferred and other income tax expenses	1,571,000	(5,136,000)	(7,536,000)
Total income tax expenses	54,710,000	38,974,000	14,164,000
Differences between provision for income taxes and income tax expense computed by applying federal rates
Total expense computed by applying federal rates	53,557,000	40,695,000	15,255,000
State and Provincial income taxes, net of federal benefit	310,000	105,000	189,000
Adjustments of valuation allowance	(1,007,000)	(346,000)	(231,000)
Excess depletion	(1,416,000)	(1,446,000)	(1,642,000)
Acquisition related costs			1,364,000
Estimates for uncertain tax positions	551,000	437,000	1,568,000
Statutory tax attributable to Non-controlling interest	(2,042,000)	(2,066,000)	(2,775,000)
Unrealized foreign exchange gains (losses)	(546,000)	2,548,000	(280,000)
Effect of foreign earnings	511,000	(891,000)	915,000
True-up of prior year deferred assets	1,075,000
Excess 162(m) compensation	1,116,000	215,000	62,000
Other	2,601,000	(277,000)	(261,000)
Total income tax expenses	54,710,000	38,974,000	14,164,000
Deferred tax assets:
Stock-based compensation	3,984,000	3,275,000
Net operating losses	23,815,000	32,157,000
Other deferred tax assets	2,615,000	5,028,000
Total deferred tax assets	30,414,000	40,460,000
Valuation allowance	(500,000)	(3,069,000)
Net deferred tax assets	29,914,000	37,391,000
Deferred tax liabilities:
Mineral property basis	(172,146,000)	(179,344,000)
Convertible notes due 2019	(27,126,000)
Unrealized foreign exchange gains	(4,414,000)	(5,932,000)
Other deferred tax liabilities	(4,117,000)	(3,112,000)
Total deferred tax liabilities	(207,803,000)	(188,388,000)
Total net deferred taxes	(177,889,000)	(150,997,000)
Valuation allowances
Valuation allowances	500,000	3,100,000
Decrease in valuation allowance as a result of recognition of net operating losses and other deferred tax assets	2,600,000
Net operating loss carry forwards
Net operating loss carry forwards	95,000,000	127,000,000
Decrease in the net operating income carry forwards attributable to non-U.S. subsidiaries accounting income	43,000,000
Increase in the net operating loss carry forwards attributable to non-U.S. subsidiaries accelerated tax deductions	11,000,000
Increase in the net operating loss carry forwards offset by the utilization of net operating losses in non-U.S. subsidiaries	32,000,000
Reconciliation of beginning and ending amount of gross unrecognized tax benefits
Total gross unrecognized tax benefits at beginning of year	18,836,000	12,479,000	614,000
Additions / Reductions for tax positions of prior years		20,000	749,000
Additions / Reductions for tax positions of current year	2,051,000	6,337,000	11,116,000
Reductions due to lapse of statute of limitations	(1,418,000)
Total amount of gross unrecognized tax benefits at end of year	19,469,000	18,836,000	12,479,000
Net unrecognized tax benefits
Unrecognized tax benefits included in tax expense, recorded on additional pre-tax income from non-U.S. subsidiaries	900,000
Expiration period of statute of limitations for income tax examinations (in months)		12
Increase in net unrecognized income tax benefits, reasonably possible in the next 12 months, lower bound	1,000,000
Increase in net unrecognized income tax benefits, reasonably possible in the next 12 months, upper bound	1,500,000
Accrued income-tax-related interest and penalties	$ 2,800,000	$ 1,500,000