Derivative Financial Instruments (Details)	3 Months Ended
	Mar. 31, 2014
Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	17,000,000
Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	216,600,000
Natural Gas Liquids
Derivative Financial Instruments
Portion of future oil and NGL production hedged	2,900,000
IF El Paso Permian [Member]
Derivative Financial Instruments
Index percent of natural gas fixed swaps	3.00%
Index percent of natural gas collars	3.00%
IF HSC [Member]
Derivative Financial Instruments
Index percent of natural gas fixed swaps	83.00%
Index percent of natural gas collars	64.00%
IF NGPL TXOK [Member]
Derivative Financial Instruments
Index percent of natural gas fixed swaps	2.00%
Index percent of natural gas collars	3.00%
IF NNG Ventura [Member]
Derivative Financial Instruments
Index percent of natural gas fixed swaps	3.00%
Index percent of natural gas collars	6.00%
IF Reliant N/S [Member]
Derivative Financial Instruments
Index percent of natural gas fixed swaps	8.00%
Index percent of natural gas collars	16.00%
IF NGPL MidCont [Member]
Derivative Financial Instruments
Index percent of natural gas fixed swaps	1.00%
IF TETCO STX [Member]
Derivative Financial Instruments
Index percent of natural gas collars	8.00%
OPIS Mont. Belvieu LDH Propane [Member]
Derivative Financial Instruments
Index percent of NGL fixed swaps	72.00%
OPIS Mont. Belvieu Non-LDH Natural Gasoline [Member]
Derivative Financial Instruments
Index percent of NGL fixed swaps	28.00%
Swap | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	11,271,000
Swap | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	199,358,000
Swap | Natural Gas Liquids
Derivative Financial Instruments
Portion of future oil and NGL production hedged	2,917,000
Collar | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	5,693,000
Collar | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	17,196,000
Second Quarter Current Year [Member] | Swap | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	2,373,000
Weighted-Average Contract Price	94.95
Second Quarter Current Year [Member] | Swap | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	23,758,000
Weighted-Average Contract Price	3.98
Second Quarter Current Year [Member] | Swap | Natural Gas Liquids
Derivative Financial Instruments
Portion of future oil and NGL production hedged	1,096,000
Weighted-Average Contract Price	58.04
Second Quarter Current Year [Member] | Collar | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	431,000
Weighted-Average Floor Price	85.00
Weighted-Average Ceiling Price	102.50
Second Quarter Current Year [Member] | Collar | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	4,194,000
Weighted-Average Floor Price	4.38
Weighted-Average Ceiling Price	5.29
Third Quarter Current Year [Member] | Swap | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	1,533,000
Weighted-Average Contract Price	96.04
Third Quarter Current Year [Member] | Swap | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	24,541,000
Weighted-Average Contract Price	4.02
Third Quarter Current Year [Member] | Swap | Natural Gas Liquids
Derivative Financial Instruments
Portion of future oil and NGL production hedged	960,000
Weighted-Average Contract Price	58.06
Third Quarter Current Year [Member] | Collar | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	973,000
Weighted-Average Floor Price	85.00
Weighted-Average Ceiling Price	102.58
Fourth Quarter Current Year [Member] | Swap | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	1,353,000
Weighted-Average Contract Price	94.88
Fourth Quarter Current Year [Member] | Swap | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	22,014,000
Weighted-Average Contract Price	4.02
Fourth Quarter Current Year [Member] | Swap | Natural Gas Liquids
Derivative Financial Instruments
Portion of future oil and NGL production hedged	861,000
Weighted-Average Contract Price	58.06
Fourth Quarter Current Year [Member] | Collar | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	923,000
Weighted-Average Floor Price	85.00
Weighted-Average Ceiling Price	102.63
2015 [Member] | Swap | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	3,308,000
Weighted-Average Contract Price	89.34
2015 [Member] | Swap | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	57,943,000
Weighted-Average Contract Price	4.04
2015 [Member] | Collar | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	3,366,000
Weighted-Average Floor Price	85.00
Weighted-Average Ceiling Price	94.25
2015 [Member] | Collar | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	13,002,000
Weighted-Average Floor Price	3.98
Weighted-Average Ceiling Price	4.30
2016 [Member] | Swap | Crude oil
Derivative Financial Instruments
Portion of future oil and NGL production hedged	2,704,000
Weighted-Average Contract Price	85.19
2016 [Member] | Swap | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	37,472,000
Weighted-Average Contract Price	4.17
2017 [Member] | Swap | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	23,430,000
Weighted-Average Contract Price	4.21
2018 [Member] | Swap | Natural Gas
Derivative Financial Instruments
Portion of Gas Production Being Hedged	10,200,000
Weighted-Average Contract Price	4.31
Revolving Credit Facility [Member]
Derivative Financial Instruments
Percentage of Proved Oil and Gas Properties Secured for Credit Facility Borrowing	75.00%