v3.22.4
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - OCI and tax effects (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Pre-Tax Amount      
Other comprehensive income (loss), before tax $ (49.2) $ (66.8) $ 64.6
Tax (Expense) Benefit      
Other comprehensive income (loss), tax   (0.2) 0.2
Net-of-Tax Amount      
Realized loss on foreign currency transactions reclassified into investment expense (income), net of tax   (0.4) 1.9
Other comprehensive income (loss) (49.2) (67.0) 64.8
Foreign Currency      
Pre-Tax Amount      
Unrealized foreign currency translation adjustment arising during the period (59.8) (78.9) 66.8
Realized gain (loss) on foreign currency transactions   (0.9) 1.9
Tax (Expense) Benefit      
Unrealized foreign currency translation adjustment arising during the period, tax     0.2
Realized gain (loss) on foreign currency transactions, net of tax   0.5  
Net-of-Tax Amount      
Unrealized foreign currency translation adjustment arising during the period, net of tax (59.8) (78.9) 67.0
Realized loss on foreign currency transactions reclassified into investment expense (income), net of tax   (0.4) 1.9
Pension and other benefit adjustments      
Pre-Tax Amount      
Unrealized foreign currency translation adjustment arising during the period 10.6 13.0 (4.1)
Tax (Expense) Benefit      
Unrealized foreign currency translation adjustment arising during the period, tax   (0.7)  
Net-of-Tax Amount      
Unrealized foreign currency translation adjustment arising during the period, net of tax $ 10.6 $ 12.3 $ (4.1)