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Supplemental Information on Oil And Gas Producing Activities (Unaudited) - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2017
Rate
MMBbls
Bcf
MMBoe
Dec. 31, 2016
MMBbls
Bcf
MMBoe
Dec. 31, 2015
MMBbls
Bcf
MMBoe
Disclosure of discounted future net cash flow [Line Items]      
Extension and discoveries of proved development reserves 26 42 54
Extension and discoveries of proved undevelopment reserves 54 79 93
Net proved reserves of oil equivalent, Improved recovery 32 35 23
Proved developed reserves of sales and acquisition 2.3 19.5  
Revised proved reserves 96 89 71
Proved developed reserves reduced due to lower average oil price 105 105  
Proved undeveloped reserves revisions of previous estimates of economic conditions decreases 20 45  
Proved developed reserves revisions of previous estimates increases by liquids and gas production performance 25 68 56
Proved developed reserves revisions of previous estimates increases by well performance 48 80  
Proved reserves revisions of previous estimates of feasibility studies increases 5.6 12  
Proved reserves revisions of previous estimates of Production and forecast Decreases 7 10 10
Net proved reserves of sales and acquisition   30.7  
Proved undeveloped reserves of sales and acquisition   11.2  
Net proved reserves declined after sales and acquisition     16.3
Proved developed reserves declined after sales and acquisition     (8.2)
Proved undeveloped reserves declined after sales and acquisition     (8.1)
Percentage of discount rate 10.00%    
Selling exchange rate | Rate 18.599    
Golfo San Jorge basin [Member]      
Disclosure of discounted future net cash flow [Line Items]      
Proved developed reserves of oil equivalent, Improved reserves 5.6 8 8
Proved undeveloped reserves of oil equivalent, Improved reserves 9.6 17 5
Proved developed reserves reduced due to lower average oil price (25) (40)  
Proved undeveloped reserves revisions of previous estimates of economic conditions decreases (3) (16)  
Proved developed reserves revisions of previous estimates increases by well performance 14 42  
Proved reserves revisions of previous estimates of feasibility studies increases 3.5 2  
Revision due to reservoirs current performance     17
Proved reserves removed due to impact of lower average oil prices     21
Neuquina basin [Member]      
Disclosure of discounted future net cash flow [Line Items]      
Proved developed reserves of oil equivalent, Improved reserves 5.4 7 5
Proved undeveloped reserves of oil equivalent, Improved reserves 10 2 3
Proved developed reserves reduced due to lower average oil price (60) (43)  
Proved undeveloped reserves revisions of previous estimates of economic conditions decreases (15) (15)  
Proved developed reserves revisions of previous estimates increases by well performance 31 27  
Proved developed reserves revisions of previous estimates decreases by well performance 23 12  
Proved reserves revisions of previous estimates of feasibility studies increases 2.1 10  
Revision due to reservoirs current performance     21
Golfo San Jorge And Neuquina Basins [Member]      
Disclosure of discounted future net cash flow [Line Items]      
Proved reserves revisions of previous estimates of WO jobs performance increases 4.2    
Crude oil [Member]      
Disclosure of discounted future net cash flow [Line Items]      
Extension and discoveries of proved development reserves | MMBbls 7.4 15.5 20
Extension and discoveries of proved undevelopment reserves | MMBbls 11.7 29 24
Revised proved reserves | MMBbls 71 75 31
Proved developed reserves revisions of previous estimates increases by liquids and gas production performance | MMBbls     29.3
Revision due to reservoirs current performance | MMBbls     8.8
Proved reserves removed due to impact of lower average oil prices | MMBbls     9.4
Natural Gas Liquids [Member]      
Disclosure of discounted future net cash flow [Line Items]      
Extension and discoveries of proved development reserves | MMBbls 1.9 3.8 2
Extension and discoveries of proved undevelopment reserves | MMBbls 3.4 7 8
Revised proved reserves | MMBbls 4 5 9
Proved developed reserves revisions of previous estimates increases by liquids and gas production performance | MMBbls     5.7
Revision due to reservoirs current performance | Bcf     47.4
Natural gas [Member]      
Disclosure of discounted future net cash flow [Line Items]      
Extension and discoveries of proved development reserves | Bcf 94 128.8 178
Extension and discoveries of proved undevelopment reserves | Bcf 219 242 342
Revised proved reserves | Bcf 161 110 175
Proved developed reserves revisions of previous estimates increases by liquids and gas production performance | Bcf     117
Proved reserves removed due to impact of lower average oil prices | Bcf     64.6
Cuyana basin [Member]      
Disclosure of discounted future net cash flow [Line Items]      
Proved developed reserves reduced due to lower average oil price (14) (8)  
Proved undeveloped reserves revisions of previous estimates of economic conditions decreases   (2)  
Austral basin [Member]      
Disclosure of discounted future net cash flow [Line Items]      
Proved developed reserves reduced due to lower average oil price   (14)  
Proved undeveloped reserves revisions of previous estimates of economic conditions decreases   (12)