| **Derivative Financial Instruments**                                        | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           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| **Derivative Instruments Not Designated as Hedging Instruments [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   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| Derivative Instruments and Hedging Activities Disclosure [Text Block]       | DERIVATIVE FINANCIAL INSTRUMENTSOur results of operations and operating cash flows are affected by changes in market prices for crude oil, natural gas and NGLs. To manage a portion of our exposure to price volatility from producing crude oil and natural gas, we utilize the following economic hedging strategies for each of our business segments.•For crude oil and natural gas sales, we enter into derivative contracts to protect against price declines in future periods. While we structure these derivatives to reduce our exposure to changes in price associated with the derivative commodity, they also limit the benefit we might otherwise have received from price increases in the physical market; and •For natural gas marketing, we enter into fixed-price physical purchase and sale agreements that qualify as derivative contracts. In order to offset the fixed-price physical derivatives in our natural gas marketing, we enter into financial derivative instruments that have the effect of locking in the prices we will receive or pay for the same volumes and period, offsetting the physical derivative. We believe our derivative instruments continue to be effective in achieving the risk management objectives for which they were intended. As of March 31, 2014, we had derivative instruments, which were comprised of collars, fixed-price swaps, basis protection swaps and physical sales and purchases, in place for a portion of our anticipated production through 2017 for a total of 58,541 BBtu of natural gas and 7,687 MBbls of crude oil. The majority of our derivative contracts are entered into at no cost to us as we hedge our anticipated production at the then-prevailing commodity market prices.We have elected not to designate any of our derivative instruments as hedges and therefore do not qualify for use of hedge accounting. Accordingly, changes in the fair value of our derivative instruments are recorded in the statements of operations. Changes in the fair value of derivative instruments related to our Oil and Gas Exploration and Production segment are recorded in commodity price risk management, net. Changes in the fair value of derivative instruments related to our Gas Marketing segment are recorded in sales from and cost of natural gas marketing.The following table presents the location and fair value amounts of our derivative instruments on the condensed consolidated balance sheets as of March 31, 2014 and December 31, 2013:      Fair ValueDerivatives instruments: Balance sheet line item March 31, 2014 December 31, 2013     (in thousands)Derivative assets:Current       Commodity contracts       Related to crude oil and natural gas sales Fair value of derivatives $552 $2,016 Related to natural gas marketing Fair value of derivatives 275 361 Basis protection contracts       Related to crude oil and natural gas sales Fair value of derivatives — 195     827 2,572 Non-current       Commodity contracts       Related to crude oil and natural gas sales Fair value of derivatives 2,214 5,055 Related to natural gas marketing Fair value of derivatives 202 278 Basis protection contracts       Related to crude oil and natural gas sales Fair value of derivatives 150 268     2,566 5,601Total derivative assets    $3,393 $8,173        Derivative liabilities:Current       Commodity contracts       Related to crude oil and natural gas sales Fair value of derivatives $28,921 $15,263 Related to natural gas marketing Fair value of derivatives 171 247 Basis protection contracts       Related to crude oil and natural gas sales Fair value of derivatives 120 — Related to natural gas marketing Fair value of derivatives 2 5     29,214 15,515 Non-current       Commodity contracts       Related to crude oil and natural gas sales Fair value of derivatives 3,302 2,782 Related to natural gas marketing Fair value of derivatives 165 233     3,467 3,015Total derivative liabilities    $32,681 $18,530    The following table presents the impact of our derivative instruments on our statements of operations:  Three Months Ended March 31,Condensed consolidated statement of operations line item 2014 2013  (in thousands)Commodity price risk management loss, net    Net settlements $(8,240) $8,474Net change in fair value of unsettled derivatives (18,915) (30,829)Total commodity price risk management loss, net $(27,155) $(22,355)Sales from natural gas marketing    Net settlements $(476) $201Net change in fair value of unsettled derivatives (312) (968)Total sales from natural gas marketing $(788) $(767)Cost of natural gas marketing    Net settlements $535 $(162)Net change in fair value of unsettled derivatives 296 1,076Total cost of natural gas marketing $831 $914All of our financial derivative agreements contain master netting provisions that provide for the net settlement of all contracts through a single payment in the event of early termination. Our fixed-price physical purchase and sale agreements that qualify as derivative contracts are not subject to master netting provisions and are not significant. We have elected not to offset the fair value positions recorded on our condensed consolidated balance sheets.The following table reflects the impact of netting agreements on gross derivative assets and liabilities as of March 31, 2014 and December 31, 2013:As of March 31, 2014 Derivatives instruments, recorded in condensed consolidated balance sheet, gross Effect of master netting agreements Derivative instruments, net  (in thousands)Asset derivatives:      Derivative instruments, at fair value $3,393 $(2,164) $1,229       Liability derivatives:      Derivative instruments, at fair value $32,681 $(2,164) $30,517       As of December 31, 2013 Derivatives instruments, recorded in condensed consolidated balance sheet, gross Effect of master netting agreements Derivative instruments, net  (in thousands)Asset derivatives:      Derivative instruments, at fair value $8,173 $(5,623) $2,550       Liability derivatives:      Derivative instruments, at fair value $18,530 $(5,623) $12,907        |

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| - Definition
The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.
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