| Carbon Dioxide Tax on Certain Energy Products; Act 321/2011             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Denmark             | 
                                                                                                        1991             | 
                  
              
                                                                                                        | Energy Decree             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Switzerland             | 
                                                                                                        1991             | 
                  
              
                                                                                                        | Energy2000 Programme             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Switzerland             | 
                                                                                                        1991             | 
                  
              
                                                                                                        | Mini-hydroelectric Power Incentive Act (RA 7156)             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Philippines             | 
                                                                                                        1991             | 
                  
              
                                                                                                        | Renewable Energy Pogramme             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Spain             | 
                                                                                                        1991             | 
                  
              
                                                                                                        | CO2 Tax             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Sweden             | 
                                                                                                        1991             | 
                  
              
                                                                                                        | Building Energy Codes Program             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        United States of America             | 
                                                                                                        1991             | 
                  
              
                                                                                                        | Clean Air Conservation Act             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Republic of Korea             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | ERP-Environment and Energy Saving Programme             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Germany             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Electricity Business Act             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Republic of Korea             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Fuel compliance             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        United States of America             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Global Change Research Act             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        United States of America             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Joint Forest Management             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        India             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Non-Fossil Fuel Obligation             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        United Kingdom             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Resolution on Ambient Air Quality Standards             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Brazil             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Significant New Alternatives Policy (SNAP) Program             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        United States of America             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Stationary Diesel Engines (NSPS) standards             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        United States of America             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | The National Landcare Programme             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Australia             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Requirements for Process emissions, emissions related to hazardus and toxic substances             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        United States of America             | 
                                                                                                        1990             | 
                  
              
                                                                                                        | Energy Law (Law No. 7200)             | 
                                                                                                        
             | 
                                                                                                        
             | 
                                                                                                        Costa Rica             | 
                                                                                                        1990             |