FAIR VALUE MEASUREMENTS AND DISCLOSURES Fair Value Measurements and Disclosures (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Fair Value | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity Based Derivative Assets	$ 5,325,000	$ 42,798,000
Basis Protection Derivative Assets	463,000	377,000
Assets, Fair Value Disclosure	5,788,000	43,175,000
Commodity Based Derivative Liabilities	17,537,000	9,839,000
Basis Protection Derivative Liabilities	5,000	16,656,000
Liabilities, Fair Value Disclosure	17,542,000	26,495,000
Net Asset Fair Value	(11,754,000)	16,680,000
Fair Value | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity Based Derivative Assets	2,385,000	15,750,000
Basis Protection Derivative Assets	0	0
Assets, Fair Value Disclosure	2,385,000	15,750,000
Commodity Based Derivative Liabilities	988,000	2,081,000
Basis Protection Derivative Liabilities	0	0
Liabilities, Fair Value Disclosure	988,000	2,081,000
Net Asset Fair Value	1,397,000	13,669,000
Fair Value | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity Based Derivative Assets	7,710,000	58,548,000
Basis Protection Derivative Assets	463,000	377,000
Assets, Fair Value Disclosure	8,173,000	58,925,000
Commodity Based Derivative Liabilities	18,525,000	11,920,000
Basis Protection Derivative Liabilities	5,000	16,656,000
Liabilities, Fair Value Disclosure	18,530,000	28,576,000
Net Asset Fair Value	(10,357,000)	30,349,000
3.25% Convertible Senior Notes due 2016 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.25%
3.25% convertible senior notes fair value	165,400,000
3.25% convertible senior notes fair value as a percentage of par	143.90%
7.75% Senior Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.75%
7.75% senior notes fair value	$ 543,100,000
7.75% senior notes fair value as percentage of par	108.60%