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Pension and Other Postretirement Benefits - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]      
Defined contribution expense $ 12.6 $ 11.8 $ 11.1
Accumulated benefit obligation 272.5 296.4  
Project benefit obligation for the pension plans with an accumulated benefit obligation in excess of plan assets 228.3 247.5  
Accumulated benefit obligation for the pension plans with an accumulated benefit obligation in excess of assets 225.4 243.9  
Fair value of plan assets for the pension plans with an accumulated benefit obligations in excess of plan assets 150.2 158.2  
Projected benefit obligation for the pension plans with an accumulated benefit less than plan assets 46.9 52.8  
Accumulated benefit obligation for the pension plans with an accumulated benefit obligation less than plan assets 47.1 52.5  
Fair value of plan assets for the pension plans with an accumulated benefit obligations less than plan assets $ 54.1 $ 58.5  
Target asset allocation for the investment of the assets in equity securities minimum 20.00%    
Target asset allocation for the investment of the assets in equity securities maximum 25.00%    
Target asset allocation for the investment of the assets in fixed income securities minimum 75.00%    
Target asset allocation for the investment of the assets in fixed income securities maximum 80.00%    
Minimum [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Target asset allocation for the investment of the assets in fixed income securities 30.00%    
Target asset allocation for the investment of the assets in equity securities 60.00%    
Maximum [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Target asset allocation for the investment of the assets in fixed income securities 40.00%    
Target asset allocation for the investment of the assets in equity securities 70.00%    
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Pension and other postretirement plans $ 5.2    
Other Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Pension and other postretirement plans $ 2.0