text: We use derivatives only to manage risk, and not for speculative 
  purposes. 
  We assess whether an embedded derivative is required to be separated 
  from the host contract and accounted for as a derivative when we first 
  become a party to the contract. 
  
  We record all derivatives on our consolidated statements of financial 
  their estimated fair value. We record changes in the 
  position at 
  estimated fair value of derivative instruments 
  that are effective 
  accounting hedges in other comprehensive income until the hedged 
  item impacts net income. Hedge ineffectiveness is recognized in net 
  income immediately. Any changes in the estimated fair value of 
  derivative instruments that have not been designated as hedging 
  instruments for accounting purposes are recognized immediately in net 
  income. 
  
  **Earnings Per Share**
  We calculate basic earnings per share by dividing the net income or loss 
  attributable to our Class A and B shareholders by the weighted average 
  number of Class A and B shares outstanding during the year. 
  
  We calculate diluted earnings per share by adjusting the net income or 
  loss attributable to Class A and B shareholders and the weighted 
  average number of Class A and B shares outstanding for the effect of 
  all dilutive potential common shares. We use the treasury stock method 
  for calculating diluted earnings per share, which considers the impact of 
  employee stock options and other potentially dilutive instruments. 
  
  When we designate a derivative instrument as a hedging instrument for 
  accounting purposes, we: 
  (cid:129) first determine that the hedging instrument will be highly effective in 
  offsetting the changes in fair value or cash flows of the item it is 
  hedging, and 