Annual report pursuant to Section 13 and 15(d)

Components of Net Periodic Benefit Cost (Detail)

v2.4.0.6
Components of Net Periodic Benefit Cost (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Pension Benefits
      
Defined Benefit Plan Disclosure [Line Items]      
Service cost $ 6.5 $ 6.4 $ 6.4
Interest cost 33.4 34.5 34.9
Expected return on plan assets (46.6) (46.6) (44.8)
Amortization of prior service cost 0.8 0.8 0.8
Recognized actuarial loss 16.0 12.0 9.2
Net periodic benefit cost 10.1 7.1 6.5
Curtailments (0.2)    
Settlements 38.9    
Total net periodic benefit cost 48.8 7.1 6.5
Other Benefits
      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 0.5 0.6 0.5
Interest cost 1.2 1.6 1.7
Expected return on plan assets (1.6) (1.7) (1.5)
Amortization of prior service cost (0.2) (0.2) (0.2)
Recognized actuarial loss 1.1 1.3 1.2
Net periodic benefit cost 1.0 1.6 1.7
Curtailments   0  
Settlements   0  
Total net periodic benefit cost $ 1.0 $ 1.6 $ 1.7