XML 58 R45.htm IDEA: XBRL DOCUMENT v3.8.0.1
STOCKHOLDERS' EQUITY: - Treasury Stock (Details) - USD ($)
$ in Millions
 9 Months Ended 117 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Activity in treasury stock      
Balance at the beginning of the period $ 2,987.6    
Cost of purchase of shares     $ 2,900.0
Balance at the end of the period $ 2,996.7 $ 2,987.0 $ 2,996.7
Southern copper common shares      
Activity in treasury stock      
Treasury stock balance at the end of the period (in shares) 111,567,617 110,579,617 111,567,617
Southern copper common shares | Directors' Stock Award Plan      
Share Based Compensation Plan, share distributions      
Share Based Compensation Plan, share distributions during the period 12,000 12,000  
Parent Company (Grupo Mexico) common shares      
Activity in treasury stock      
Treasury stock balance at the end of the period (in shares) 110,941,769 115,781,665 110,941,769
Parent Company (Grupo Mexico) common shares | Employee Stock Purchase Plan      
Share Based Compensation Plan, share distributions      
Share Based Compensation Plan, share distributions during the period 300,000 900,000  
TREASURY STOCK: | Southern copper common shares      
Activity in treasury stock      
Balance at the beginning of the period $ 2,769.0 $ 2,697.6  
Cost of purchase of shares   71.7  
Used for corporate purposes (0.3) (0.3)  
Balance at the end of the period 2,768.7 2,769.0 $ 2,768.7
TREASURY STOCK: | Parent Company (Grupo Mexico) common shares      
Activity in treasury stock      
Balance at the beginning of the period 218.6 211.3  
Other activity, including dividend, interest and foreign currency transaction effect 9.4 6.7  
Balance at the end of the period $ 228.0 $ 218.0 $ 228.0