Annual report pursuant to Section 13 and 15(d)

Supplemental Information On Oil And Gas Producing Activities (Net Proved Reserves) (Detail)

v3.3.1.900
Supplemental Information On Oil And Gas Producing Activities (Net Proved Reserves) (Detail)
 12 Months Ended
Dec. 31, 2015
MMcf
MBbls
Dec. 31, 2014
MMcf
MBbls
Dec. 31, 2013
MMcf
MBbls
Dec. 31, 2012
MMcf
MBbls
Oil [Member]        
Proved Reserves:        
Beginning Balance 8,260 7,232 7,488  
Production (1,659) (1,351) (1,549)  
Revisions of previous estimates (3,746) 2,312 771  
Extensions and discoveries   67 522  
Ending Balance 2,855 8,260 7,232  
Proved Developed Reserves 2,855 3,224 3,305 3,750
Gas [Member]        
Proved Reserves:        
Beginning Balance | MMcf [1] 1,406 1,333 1,544  
Production | MMcf [1] (181) (227) (325)  
Revisions of previous estimates | MMcf [1] (172) 300 114  
Ending Balance | MMcf [1] 1,053 1,406 1,333  
Proved Developed Reserves | MMcf 1,053 1,406 1,333 1,544
Natural Gas Liquids [Member]        
Proved Reserves:        
Natural gas liquids, MMcf to MBbl ratio 4.90%      
[1] The natural gas reserves shown as of December 31, 2015 include natural gas liquids ("NGL") expressed as gas volumes using a ratio of 4.9 MMcf to 1 MBbl of NGL.