v2.4.0.6
Impairments (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Impairment charges by segment, before-tax        
Impairments $ 0 $ 0 $ 296 $ 0
Canada [Member]
       
Impairment charges by segment, before-tax        
Impairments     213  
Europe [Member]
       
Impairment charges by segment, before-tax        
Impairments 0   79  
Asia Pacific and Middle East [Member]
       
Impairment charges by segment, before-tax        
Impairments $ 0   $ 4