Annual report pursuant to Section 13 and 15(d)

BENEFIT PLANS (Fair Value of Postretirement Assets) (Detail)

v3.3.1.900
BENEFIT PLANS (Fair Value of Postretirement Assets) (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]      
Hedge funds, minimum number of days notice prior to redemption 30 days    
Hedge funds, maximum number of days notice prior to redemption 90 days    
Other Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 18.9 $ 20.8 $ 21.6
Other Benefits | Large-Cap Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 4.8    
Other Benefits | Small- and Mid-Cap Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.1    
Other Benefits | International Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 2.2    
Other Benefits | Fixed Income      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 5.4    
Other Benefits | Private Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.6    
Other Benefits | Hedge Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 2.1    
Other Benefits | Real Assets      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.7    
Other Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.0    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 6.9    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Large-Cap Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 4.8    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Small- and Mid-Cap Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.1    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | International Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.6    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Fixed Income      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Private Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Hedge Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Real Assets      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.4    
Significant Other Observable Inputs (Level 2) | Other Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 7.0    
Significant Other Observable Inputs (Level 2) | Other Benefits | Large-Cap Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Other Observable Inputs (Level 2) | Other Benefits | Small- and Mid-Cap Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Other Observable Inputs (Level 2) | Other Benefits | International Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.6    
Significant Other Observable Inputs (Level 2) | Other Benefits | Fixed Income      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 5.4    
Significant Other Observable Inputs (Level 2) | Other Benefits | Private Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Other Observable Inputs (Level 2) | Other Benefits | Hedge Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Other Observable Inputs (Level 2) | Other Benefits | Real Assets      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Other Observable Inputs (Level 2) | Other Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Unobservable Inputs (Level 3) | Other Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 4.4    
Significant Unobservable Inputs (Level 3) | Other Benefits | Large-Cap Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Unobservable Inputs (Level 3) | Other Benefits | Small- and Mid-Cap Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Unobservable Inputs (Level 3) | Other Benefits | International Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Unobservable Inputs (Level 3) | Other Benefits | Fixed Income      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0    
Significant Unobservable Inputs (Level 3) | Other Benefits | Private Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.6    
Significant Unobservable Inputs (Level 3) | Other Benefits | Hedge Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 2.1    
Significant Unobservable Inputs (Level 3) | Other Benefits | Real Assets      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.7    
Significant Unobservable Inputs (Level 3) | Other Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 0.0