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Supplemental Crude Oil and Natural Gas Information - Additional Information (Detail)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2015
$ / Barrels
Dec. 31, 2015
MBoe
Dec. 31, 2015
MBbls
Dec. 31, 2015
MMcf
Dec. 31, 2014
$ / bbl
$ / Mcf
MBoe
MBbls
MMcf
Dec. 31, 2013
$ / bbl
$ / Mcf
MBoe
MBbls
MMcf
Reserve Quantities [Line Items]              
Percentage of discounted future net cash flows prepared by external reserve engineers 99.00%         99.00% 99.00%
Percent of proved crude oil reserve estimates prepared by external reserve engineers 99.00%            
Percent of proved natural gas reserve estimates prepared by external reserve engineers 97.00%            
Revisions of previous estimates | MBoe     (297,198)     (107,949) (96,054)
Extensions, discoveries and other additions | MBoe     253,173     440,621 444,654
Discount factor utilized as standardized measure for future net cash flows 10.00%            
Crude Oil [Member]              
Reserve Quantities [Line Items]              
Weighted average price utilized in computation of future cash inflows   41.63       84.54 91.50
Crude Oil [Member]              
Reserve Quantities [Line Items]              
Percentage change in average SEC price 47.00%            
Revisions of previous estimates | MBbls       (246,840)   (67,151) (55,783)
Extensions, discoveries and other additions | MBbls       134,764   239,526 267,009
Natural Gas [Member]              
Reserve Quantities [Line Items]              
Percentage change in average SEC price 41.00%            
Revisions of previous estimates | MMcf         (302,143) (244,783) (241,623)
Extensions, discoveries and other additions | MMcf         710,453 1,206,569 1,065,870
Weighted average price utilized in computation of future cash inflows   2.35       6.06 5.36
Proved Undeveloped Reserves [Domain]              
Reserve Quantities [Line Items]              
Revisions of previous estimates | MBoe     98        
Proved Undeveloped Reserves [Domain] | Natural Gas [Member]              
Reserve Quantities [Line Items]              
Revisions of previous estimates | MBbls       197      
Proved Undeveloped Reserves [Domain] | Crude Oil [Member]              
Reserve Quantities [Line Items]              
Revisions of previous estimates | MBbls       65      
Bakken [Member]              
Reserve Quantities [Line Items]              
Extensions, discoveries and other additions       75,000 124,000    
Extensions, discoveries and other additions | MBoe     96,000        
SCOOP [Member]              
Reserve Quantities [Line Items]              
Extensions, discoveries and other additions       36,000 340,000    
Extensions, discoveries and other additions | MBoe     93,000        
Northwest Cana [Member]              
Reserve Quantities [Line Items]              
Extensions, discoveries and other additions       20,000 222,000    
Extensions, discoveries and other additions | MBoe     57,000        
Price Driven [Domain] | Proved Reserves [Domain]              
Reserve Quantities [Line Items]              
Revisions of previous estimates | MBoe     251        
Price Driven [Domain] | Proved Reserves [Domain] | Natural Gas [Member]              
Reserve Quantities [Line Items]              
Revisions of previous estimates | MBbls       391      
Price Driven [Domain] | Proved Reserves [Domain] | Crude Oil [Member]              
Reserve Quantities [Line Items]              
Revisions of previous estimates | MBbls       185      
Production [Domain] | Proved Reserves [Domain]              
Reserve Quantities [Line Items]              
Revisions of previous estimates | MBoe     42        
Production [Domain] | Proved Reserves [Domain] | Natural Gas [Member]              
Reserve Quantities [Line Items]              
Revisions of previous estimates | MBbls       125      
Production [Domain] | Proved Reserves [Domain] | Crude Oil [Member]              
Reserve Quantities [Line Items]              
Revisions of previous estimates | MBbls       63