v2.4.0.6
Changes in Accumulated Other Comprehensive Income by Component (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward]    
Beginning balance, December 31, 2012 $ 5.8  
Other comprehensive income before reclassifications (1.6)  
Amounts reclassified from accumulated other comprehensive income 0.5  
Other comprehensive income, net of tax (1.1) (4.2)
Ending balance, March 31, 2013 4.7  
Gains and Losses on Cash Flow Hedges [Member]
    
Accumulated Other Comprehensive Income (Loss) [Roll Forward]    
Beginning balance, December 31, 2012 23.1  
Other comprehensive income before reclassifications (1.6)  
Amounts reclassified from accumulated other comprehensive income 0.5  
Other comprehensive income, net of tax (1.1)  
Ending balance, March 31, 2013 22.0  
Defined Benefit Pension Items [Member]
    
Accumulated Other Comprehensive Income (Loss) [Roll Forward]    
Beginning balance, December 31, 2012 (17.3)  
Other comprehensive income before reclassifications 0  
Amounts reclassified from accumulated other comprehensive income 0  
Other comprehensive income, net of tax 0  
Ending balance, March 31, 2013 $ (17.3)