FAIR VALUE MEASUREMENTS AND DISCLOSURES Fair Value Measurements and Disclosures (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
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	$ 174,657	$ 237,939
Basis Protection Derivative Assets	101	19
Assets, Fair Value Disclosure	174,758	237,958
Commodity Based Derivative Liabilities	738	742
Basis Protection Derivative Liabilities	1,552	25
Liabilities, Fair Value Disclosure	2,290	767
Net Asset Fair Value	172,468	237,191
Fair Value | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity Based Derivative Assets	91,288	62,356
Basis Protection Derivative Assets	0	0
Assets, Fair Value Disclosure	91,288	62,356
Commodity Based Derivative Liabilities	0	0
Basis Protection Derivative Liabilities	0	0
Liabilities, Fair Value Disclosure	0	0
Net Asset Fair Value	91,288	62,356
Fair Value | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity Based Derivative Assets	265,945	300,295
Basis Protection Derivative Assets	101	19
Assets, Fair Value Disclosure	266,046	300,314
Commodity Based Derivative Liabilities	738	742
Basis Protection Derivative Liabilities	1,552	25
Liabilities, Fair Value Disclosure	2,290	767
Net Asset Fair Value	$ 263,756	$ 299,547
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	$ 150,200
3.25% convertible senior notes fair value as a percentage of par	130.60%
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	$ 485,000
7.75% senior notes fair value as percentage of par	97.00%