v3.20.1
BASIS OF PRESENTATION - AOCL and Accumulated Depreciation and Amortization (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2020
Dec. 31, 2019
Accumulated other comprehensive loss    
Balance at the beginning of the period $ 1,214.2  
Balance at the end of the period (1,074.0)  
Accumulated depreciation and amortization    
Accumulated depreciation 1,937.4 $ 1,820.1
Accumulated amortization 23.7 $ 22.8
Foreign Currency    
Accumulated other comprehensive loss    
Balance at the beginning of the period (8.8)  
Other comprehensive loss before reclassifications (93.6)  
Balance at the end of the period (102.4)  
Pension and Other Benefits    
Accumulated other comprehensive loss    
Balance at the beginning of the period (17.3)  
Amounts reclassified from accumulated other comprehensive loss 0.1  
Balance at the end of the period (17.2)  
Accumulated Other Comprehensive Loss    
Accumulated other comprehensive loss    
Balance at the beginning of the period (26.1)  
Other comprehensive loss before reclassifications (93.6)  
Amounts reclassified from accumulated other comprehensive loss 0.1  
Balance at the end of the period $ (119.6)