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Supplemental Information on Oil And Gas Producing Activities (Unaudited) - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2018
MMBbls
Bcf
Rate
MMBoe
Dec. 31, 2017
MMBbls
Bcf
MMBoe
Dec. 31, 2016
MMBbls
Bcf
MMBoe
MBbls
Disclosure of discounted future net cash flow [line items]      
Extension and discoveries of proved development reserves 25 26 42
Extension and discoveries of proved undevelopment reserves 149 54 79
Net proved reserves of oil equivalent, Improved recovery 15 32 35
Proved developed reserves of sales and acquisition 1.4   19.5
Revised proved reserves 156 96 89
Proved developed reserves added due to higher average oil price 143    
Proved undeveloped reserves revisions of previous estimates of economic conditions increases-decreases 48 20 45
Proved developed reserves revisions of previous estimates increases by liquids and gas production performance 33 25 68
Proved reserves revisions of previous estimates of change of development strategy 43    
Proved reserves revisions of previous estimates of Production and forecast Decreases 13 7 10
Net proved reserves of sales and acquisition   2.3 30.7
Proved developed reserves reduced due to lower average oil price   105 105
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 undeveloped reserves of sales and acquisition     11.2
Percentage of discount rate 10.00%    
Selling exchange rate | Rate 37.60    
Golfo San Jorge basin [Member]      
Disclosure of discounted future net cash flow [line items]      
Proved developed reserves of oil equivalent, Improved reserves 4.4 5.6 8
Proved undeveloped reserves of oil equivalent, Improved reserves 8 9.6 17
Proved developed reserves added due to higher average oil price 40    
Proved undeveloped reserves revisions of previous estimates of economic conditions decreases 33 3 16
Proved developed reserves reduced due to lower average oil price   (25) (40)
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
Neuquina basin [Member]      
Disclosure of discounted future net cash flow [line items]      
Proved developed reserves of oil equivalent, Improved reserves 3 5.4 7
Proved undeveloped reserves of oil equivalent, Improved reserves 3 10 2
Proved developed reserves added due to higher average oil price 56    
Proved undeveloped reserves revisions of previous estimates of economic conditions decreases 15 15 15
Reduction of proved undeveloped reserves due to changes in gas compression projects 5    
Proved developed reserves reduced due to lower average oil price   (60) (43)
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
Austral, Golfo San Jorge and Cuyana basins [member]      
Disclosure of discounted future net cash flow [line items]      
Proved undeveloped reserves reduction 5    
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 8 7.4 15.5
Extension and discoveries of proved undevelopment reserves | MMBbls 95 11.7 29
Revised proved reserves 126 71 75
Natural Gas Liquids [Member]      
Disclosure of discounted future net cash flow [line items]      
Extension and discoveries of proved development reserves | MMBbls 1 1.9 3.8
Extension and discoveries of proved undevelopment reserves | MMBbls 12 3.4 7
Revised proved reserves 1 4 5
Natural gas [member]      
Disclosure of discounted future net cash flow [line items]      
Extension and discoveries of proved development reserves | Bcf 92 94 128.8
Extension and discoveries of proved undevelopment reserves | Bcf 238 219 242
Revised proved reserves | Bcf 178 161 110
Austral basin [Member]      
Disclosure of discounted future net cash flow [line items]      
Proved developed reserves added due to higher average oil price 31    
Proved undeveloped reserves revisions of previous estimates of economic conditions decreases     12
Proved developed reserves reduced due to lower average oil price     (14)
Cuyana basin [Member]      
Disclosure of discounted future net cash flow [line items]      
Proved undeveloped reserves revisions of previous estimates of economic conditions decreases     2
Proved developed reserves reduced due to lower average oil price   (14) (8)