SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) | 9 Months Ended |
|---|---|
Sep. 30, 2011
facility
quarter
Y
segment | |
| Inventory and Long-Term Parts Inventory | |
| Period after which inventory is classified as non-current (in years) | 1 |
| Mineral Properties and Development Costs | |
| Upper limit on estimated lives of mineral properties (in years) | 25-year |
| Cash and Cash Equivalents | |
| Maximum original maturity period of cash and liquid investments (in months) | Three months or less |
| Investments | |
| Maximum maturity period of short-term investments (in years) | Less than or equal to one year |
| Minimum maturity period of long-term investments (in years) | Greater than one year |