FAIR VALUE MEASUREMENTS (Details) (Fair Value, Measurements, Recurring, Using Significant Other Observable Inputs (Level 2), USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Fair value of assets and liabilities on a recurring basis
Derivative Asset	$ 5,592	[1],[2]	$ 48,525	[1],[2]
Derivative Liability	4,542	[1],[2]	16,551	[1],[2]
Commodity
Fair value of assets and liabilities on a recurring basis
Derivative Asset	5,592	[1],[2]	35,465	[1],[2]
Derivative Liability	4,542	[1],[2]	16,551	[1],[2]
Interest rate
Fair value of assets and liabilities on a recurring basis
Derivative Asset	$ 0	[1],[2]	$ 13,060	[1],[2]

[1] Forest’s currently outstanding derivative assets and liabilities are commodity price derivatives (see Note 9 for more information on these instruments). Forest 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, Forest’s derivative instruments are included within the Level 2 fair value hierarchy.

[2] 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 relevant observable inputs are not available. There were no transfers between levels of the fair value hierarchy during 2013. Forest’s policy is to recognize transfers between levels of the fair value hierarchy as of the beginning of the reporting period in which the event or change in circumstances caused the transfer.