ASSET RETIREMENT OBLIGATIONS, CONTRACTUAL THIRD-PARTY RECLAMATION RECEIVABLES, AND RECLAMATION DEPOSITS Maturities of Available for Sale Maturities (Details) (Reclamation Deposits [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
Reclamation Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Due within one year, Amortized Cost Basis	$ 530
Due in five years or less, Amortized Cost Basis	16,397
Due after five years to ten years, Amortized Cost Basis	7,793
Due in more than ten years, Amortized Cost Basis	7,512
Available-for-sale Securities, Amortized Cost Basis	32,232
Due within one year, Fair Value	475
Due in five years or less, Fair Value	16,840
Due after five years to ten years, Fair Value	7,856
Due in more than ten years, Fair Value	7,712
Available-for-sale Securities, Fair Value	$ 32,883