Derivative Commodity Instruments - Quantitative Disclosures About Fair Value (Details) (Income Approach Valuation Technique [Member], Level 3, USD $)	3 Months Ended
	Jun. 30, 2012
Natural Gas Basis - San Juan [Member] | 2012
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	$ 24,620,000
Natural Gas Basis - San Juan [Member] | 2012 | Minimum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Cubic Foot	0.13
Natural Gas Basis - San Juan [Member] | 2012 | Maximum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Cubic Foot	0.16
Natural Gas Basis - San Juan [Member] | 2013
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	36,216,000
Natural Gas Basis - San Juan [Member] | 2013 | Minimum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Cubic Foot	0.13
Natural Gas Basis - San Juan [Member] | 2013 | Maximum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Cubic Foot	0.17
Natural Gas Basis - San Juan [Member] | 2014
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	22,498,000
Natural Gas Basis - San Juan [Member] | 2014 | Minimum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Cubic Foot	0.13
Natural Gas Basis - San Juan [Member] | 2014 | Maximum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Cubic Foot	0.16
Natural Gas Basis - Permian [Member] | 2012
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	(24)
Fair Value Inputs, Price Per Cubic Foot	0.11
Natural Gas Basis - Permian [Member] | 2013
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	(2)
Fair Value Inputs, Price Per Cubic Foot	0.13
Natural Gas Basis - Permian [Member] | 2014
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	(105)
Fair Value Inputs, Price Per Cubic Foot	0.13
Oil Basis - WTS/WTI [Member] | 2012
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	2,116,000
Oil Basis - WTS/WTI [Member] | 2012 | Minimum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Barrel	4.34
Oil Basis - WTS/WTI [Member] | 2012 | Maximum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Barrel	4.57
Oil Basis - WTS/WTI [Member] | 2013
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	(1,997,000)
Fair Value Inputs, Price Per Barrel	2.65
Natural Gas Liquids [Member] | 2012
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	8,617,000
Natural Gas Liquids [Member] | 2012 | Minimum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Gallon	0.69
Natural Gas Liquids [Member] | 2012 | Maximum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Gallon	0.81
Natural Gas Liquids [Member] | 2013
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value as of June 30, 2012	$ 11,517,000
Natural Gas Liquids [Member] | 2013 | Minimum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Gallon	0.72
Natural Gas Liquids [Member] | 2013 | Maximum [Member]
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Fair Value Inputs, Price Per Gallon	0.78