FAIR VALUE MEASUREMENTS (Details) (USD $) In Thousands	Sep. 30, 2011
Fair value of assets and liabilities on a recurring basis
Total assets	$ 87,500
Total liabilities	15,000
Fair Value, Measurements, Recurring | Using Significant Other Observable Inputs (Level 2)
Fair value of assets and liabilities on a recurring basis
Total assets	87,498	[1]
Total liabilities	14,950	[1]
Fair Value, Measurements, Recurring | Using Significant Other Observable Inputs (Level 2) | Commodity
Fair value of assets and liabilities on a recurring basis
Total assets	64,062	[1],[2]
Total liabilities	14,950	[1],[2]
Fair Value, Measurements, Recurring | Using Significant Other Observable Inputs (Level 2) | Interest rate
Fair value of assets and liabilities on a recurring basis
Total assets	23,436	[1],[2]
Total liabilities	$ 0	[1],[2]

[1] The authoritative accounting guidance regarding fair value measurements for assets and liabilities measured at fair value establishes a three-tier fair value hierarchy, which prioritizes the inputs used to measure fair value. These tiers consist of: Level 1, defined as unadjusted quoted prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs for use when little or no market data exists, therefore requiring an entity to develop its own assumptions.

[2] The Company’s derivative assets and liabilities include commodity and interest rate derivatives (see Note 8 for more information on these instruments). The Company utilizes present value techniques and option-pricing models for valuing its derivatives. Inputs to these valuation techniques include published forward prices, volatilities, and credit risk considerations, including the incorporation of published interest rates and credit spreads. All of the significant inputs are observable, either directly or indirectly; therefore, the Company’s derivative instruments are included within the Level 2 fair value hierarchy.