text: NOTE 24: STOCK OPTIONS, SHARE UNITS AND SHARE 
  PURCHASE PLANS 
  We measure stock-based compensation to employees at fair value. We 
  determine fair value using our Class B Non-Voting share price, and the 
  Black-Scholes option pricing model or trinomial option pricing models, 
  depending on the nature of the share-based award. 
  
  We paid $101 million in 2013 (2012 – $76 million) to holders of stock 
  representing a weighted 
  options, RSUs and DSUs upon exercise, 
  average share price on the date of exercise of $48.18 (2012 – $39.42). 