Derivative Commodity Instruments Derivative Commodity - Reclassification (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivatives, Fair Value [Line Items]
Deferred net gains on derivative instruments recorded in accumulated other comprehensive income, net of tax	$ 7,300,000
Revenue, Net	270,097,000	366,981,000	567,375,000	603,312,000
Production Period, Year One | NYMEX Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	4,958,000		4,958,000
Average contract price			92.65
Production Period, Year One | NYMEX Swaps | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	5,200,000		5,200,000
Average contract price ($ per Mcf)			4.56
Production Period, Year One | WTS/WTI Basis Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	600,000		600,000
Average contract price			(3.30)
Production Period, Year One | WTI/WTI Basis Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	1,200,000		1,200,000
Average contract price			(3.08)
Production Period, Year One | Liquids Swaps | Natural Gas Liquids
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	35,800,000		35,800,000
Average contract price			0.93
Production Period, Year One | Basin Specific Swaps, San Juan | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	15,400,000		15,400,000
Average contract price ($ per Mcf)			4.61
Production Period, Year One | Basin Specific Swaps - Permain | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	5,000,000		5,000,000
Average contract price ($ per Mcf)			3.81
Production Period, Year One | San Juan Basis Swaps | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	0		0
Average contract price ($ per Mcf)			(0.09)
Production Period, Year One | Permian Basis Swaps | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	0		0
Average contract price ($ per Mcf)			(0.17)
Production Period, Year Two | NYMEX Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	8,280,000		8,280,000
Average contract price			89.30
Production Period, Year Two | Basin Specific Swaps, San Juan | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	23,000,000		23,000,000
Average contract price ($ per Mcf)			4.13
Production Period, Year Two | Basin Specific Swaps - Permain | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	6,000,000		6,000,000
Average contract price ($ per Mcf)			4.20
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain from Discontinued Hedge Accounting [Member]
Derivatives, Fair Value [Line Items]
Revenue, Net			$ 3,000,000