Derivative Commodity Instruments (Reclassification) (Details) (Production Period, Year One)	12 Months Ended
	Dec. 31, 2014 mbbl
NYMEX Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	8,280
Average contract price	89.30
WTS/WTI Basis Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	2,160	[1]
Average contract price	(4.30)	[1]
WTI/WTI Basis Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	6,840	[2]
Average contract price	(4.82)	[2]
Basin Specific Swaps, San Juan | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	23.0
Average Contract Price, Per Mcf	4.13
Basin Specific Swaps - Permain | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes	8.0
Average Contract Price, Per Mcf	4.25

[1] WTS - West Texas Sour/Midland, WTI - West Texas Intermediate/Cushing

[2] WTI - West Texas Intermediate/Midland, WTI - West Texas Intermediate/Cushing