ASSET RETIREMENT OBLIGATION (Narrative) (Details) $ in Millions |
3 Months Ended |
|---|---|
|
Mar. 31, 2017
USD ($)
| |
| Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] | |
| Asset Retirement Obligation, Undiscounted Amount | $ 59.3 |
| Minimum | |
| Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] | |
| Credit Adjusted Risk-Free Rates to Discount Abandonment Liabilities | 6.90% |
| Maximum | |
| Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] | |
| Credit Adjusted Risk-Free Rates to Discount Abandonment Liabilities | 9.70% |