Summarized Cash Flow  
  Year ended December 31 (millions of dollars)  
    2006   2005   2004    
  Funds generated from operations 2,378   1,951   1,703    
  (Increase)/decrease in working capital (303 ) (49 ) 29    
  Net cash provided by operations 2,075   1,902   1,732    
  Net cash used in investing activities (2,116 ) (1,336 ) (1,648 )  
  Net cash provided by/(used in) financing activities 219   (556 ) (150 )  
  Effect of foreign exchange rate changes on cash and short-term investments 9   11   (87 )  
  Increase/(decrease) in cash and short-term investments 187   21   (153 )  
  Cash and short-term investments – beginning of year 212   191   344    
  Cash and short-term investments – end of year 399   212   191