XML 95 R76.htm IDEA: XBRL DOCUMENT v3.6.0.2
Supplemental Crude Oil and Natural Gas Information - Schedule of Proved Crude Oil and Natural Gas Reserves (Detail)
12 Months Ended
Dec. 31, 2016
$ / Barrels
MBoe
MMcf
MBbls
Dec. 31, 2015
$ / Barrels
MBoe
MMcf
MBbls
Dec. 31, 2014
MBoe
MMcf
MBbls
Dec. 31, 2013
MBoe
Reserve Quantities [Line Items]        
Proved Developed and Undeveloped Reserve, Net (Energy) | MBoe 1,274,864 1,225,811 1,351,091 1,084,125
Percentage of discounted future net cash flows prepared by external reserve engineers 99.00% 99.00% 99.00%  
Changes in Proved Reserves [Roll Forward]        
Revisions of previous estimates | MBoe (110,474) (297,198) (107,949)  
Extensions, discoveries, and other additions | MBoe 249,430 253,173 440,621  
Proved Developed and Undeveloped Reserve, Production (Energy) | MBoe 79,390 80,926 63,579  
Sales of minerals in place, Total | MBoe (10,513) (329) (3,227)  
Purchases of minerals in place, Total | MBoe 0 0 1,100  
Percent of proved crude oil reserve estimates prepared by external reserve engineers 99.00% 98.00% 98.00%  
Natural Gas [Member]        
Reserve Quantities [Line Items]        
Twelve month average SEC price | $ / Barrels 2.49 2.58    
Changes in Proved Reserves [Roll Forward]        
Proved reserves at beginning of period | MMcf 3,151,786 2,908,386 2,078,020  
Revisions of previous estimates | MMcf (63,057) (302,143) (244,783)  
Extensions, discoveries and other additions | MMcf 911,062 710,453 1,206,569  
Production | MMcf (195,240) (164,454) (114,295)  
Sales of minerals in place | MMcf (14,733) (456) (18,623)  
Purchases of minerals in place | MMcf 0 0 1,498  
Proved reserves at end of period | MMcf 3,789,818 3,151,786 2,908,386  
Crude Oil [Member]        
Reserve Quantities [Line Items]        
Twelve month average SEC price | $ / Barrels 42.75 50.28    
Changes in Proved Reserves [Roll Forward]        
Proved reserves at beginning of period | MBbls 700,514 866,360 737,788  
Revisions of previous estimates | MBbls (99,966) (246,840) (67,151)  
Extensions, discoveries and other additions | MBbls 97,587 134,764 239,526  
Production | MBbls (46,850) (53,517) (44,530)  
Sales of minerals in place | MBbls (8,057) (253) (123)  
Purchases of minerals in place | MBbls 0 0 850  
Proved reserves at end of period | MBbls 643,228 700,514 866,360