Income taxes (Tables)
9 Months Ended
Sep. 30, 2011
Income Tax Disclosure [Abstract] 
Schedule Of Components Of Income Tax Expense Benefit [TableText Block]
    Three Months Nine Months  
    Ended September 30, Ended September 30, 
    2011  2010 2011  2010 
              
 Continuing operations            
 Provision for income taxes (in millions) $ 20.9   15.5  37.9   46.1 
 Effective tax rate   36.5%  38.3% 34.9%  49.5%