Supplemental Crude Oil, Natural Gas and NGLs Information - Unaudited Schedule of Developed and Undeveloped Reserves (Details)
12 Months Ended
Dec. 31, 2013
MMcf
Dec. 31, 2012
MMcf
Natural Gas (MMcf)
   
Reserve Quantities [Line Items]    
Proved reserves, January 1, 336 [1] 997
Revisions of previous estimates and reclassifications (121) (590)
Dispositions (118) [1]  
Production (37) (71)
Proved reserves, December 31, 60 336 [1]
Proved Developed Reserves 60 336
Natural Gas (MMcf) | Piceance and NECO Asset Group
   
Reserve Quantities [Line Items]    
Proved reserves, December 31, 144  
Natural Gas Liquids (MBbl)
   
Reserve Quantities [Line Items]    
Proved reserves, January 1, 15 [1] 41
Revisions of previous estimates and reclassifications (11) (25)
Dispositions 0 [1]  
Production 0 (1)
Proved reserves, December 31, 4 15 [1]
Proved Developed Reserves 4 15
Crude Oil (MBbl)
   
Reserve Quantities [Line Items]    
Proved reserves, January 1, 26 [1] 65
Revisions of previous estimates and reclassifications (10) (37)
Dispositions (1) [1]  
Production (2) (2)
Proved reserves, December 31, 13 26 [1]
Proved Developed Reserves 13 26
Crude Oil (MBbl) | Piceance and NECO Asset Group
   
Reserve Quantities [Line Items]    
Proved reserves, December 31, 1  
Crude Oil Equivalent (MBoe)
   
Reserve Quantities [Line Items]    
Proved reserves, January 1, 97 [1] 272
Revisions of previous estimates and reclassifications (41) (160)
Dispositions (21) [1]  
Production (8) (15)
Proved reserves, December 31, 27 97 [1]
Proved Developed Reserves 27 97
Crude Oil Equivalent (MBoe) | Piceance and NECO Asset Group
   
Reserve Quantities [Line Items]    
Proved reserves, December 31, 25  
[1] Includes estimated reserve data related to this Partnership's Piceance Basin assets. In June 2013, this Partnership's Piceance Basin crude oil and natural gas properties were divested. See Note 11, Divestiture and Discontinued Operations, for additional information regarding this divestiture. As of December 31, 2012, total proved reserves related to this Partnership's Piceance Basin include 144 MMcf of natural gas and 1 MBbl of crude oil, for an aggregate of 25 MBoe.