ASSET RETIREMENT OBLIGATIONS, CONTRACTUAL THIRD-PARTY RECLAMATION RECEIVABLES, AND RECLAMATION DEPOSITS - Amortized Cost, Gross Unrealized Holding Gains and Losses and Fair Value of Available for Sale Securities (Details) (Reclamation Deposits [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Sep. 30, 2014
Reclamation Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost basis	$ 32,232
Gross unrealized holding gains	911
Gross unrealized holding losses	(260)
Fair value	$ 32,883