v3.20.4
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Change in AOCI by component (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Accumulated other comprehensive loss      
Balance at the beginning of the period $ 1,214.2    
Other comprehensive income (loss) 64.8 $ (31.6) $ (124.5)
Balance at the end of the period (2,885.1) 1,214.2  
Accumulated Other Comprehensive Income (Loss)      
Accumulated other comprehensive loss      
Balance at the beginning of the period (26.1) 5.5  
Other comprehensive (gain) loss before reclassifications 62.9 (32.1)  
Amounts reclassified from accumulated other comprehensive loss 1.9 0.5  
Other comprehensive income (loss) 64.6 (31.6) (124.5)
Balance at the end of the period 38.7 (26.1) 5.5
Foreign Currency      
Accumulated other comprehensive loss      
Balance at the beginning of the period (8.8) 7.2  
Other comprehensive (gain) loss before reclassifications 67.0 (16.5) (127.7)
Amounts reclassified from accumulated other comprehensive loss 1.9 0.5  
Balance at the end of the period 60.1 (8.8) 7.2
Pension Benefits      
Accumulated other comprehensive loss      
Balance at the beginning of the period (17.3) (1.8)  
Other comprehensive (gain) loss before reclassifications (4.1) (15.5)  
Balance at the end of the period $ (21.4) (17.3) (1.8)
Unrealized Gain (Loss) from Equity Method Investees' Cash Flow Hedge      
Accumulated other comprehensive loss      
Balance at the beginning of the period   0.1  
Other comprehensive (gain) loss before reclassifications   $ (0.1) 0.2
Amounts reclassified from accumulated other comprehensive loss     (2.2)
Balance at the end of the period     $ 0.1