Annual report pursuant to Section 13 and 15(d)

BENEFIT PLANS - Fair Value of Postretirement Assets (Details)

v3.24.0.1
BENEFIT PLANS - Fair Value of Postretirement Assets (Details) - Other Benefits - USD ($)
$ in Millions
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 10.7 $ 10.7 $ 15.0
U.S. Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.2 0.9  
International Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.0 0.8  
Fixed Income      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 7.2 8.4  
Private Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.4 0.4  
Real Assets      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.1 0.1  
Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.8 0.1  
Quoted Prices in Active Markets for Identical Assets (Level 1)      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.8 1.0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.9  
Quoted Prices in Active Markets for Identical Assets (Level 1) | International Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed Income      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Private Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Real Assets      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.8 0.1  
Significant Other Observable Inputs (Level 2)      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 9.4 9.2  
Significant Other Observable Inputs (Level 2) | U.S. Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.2 0.0  
Significant Other Observable Inputs (Level 2) | International Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 1.0 0.8  
Significant Other Observable Inputs (Level 2) | Fixed Income      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 7.2 8.4  
Significant Other Observable Inputs (Level 2) | Private Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Significant Other Observable Inputs (Level 2) | Real Assets      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Significant Other Observable Inputs (Level 2) | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Significant Unobservable Inputs (Level 3)      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.5 0.5  
Significant Unobservable Inputs (Level 3) | U.S. Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Significant Unobservable Inputs (Level 3) | International Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Significant Unobservable Inputs (Level 3) | Fixed Income      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.0 0.0  
Significant Unobservable Inputs (Level 3) | Private Equity      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.4 0.4  
Significant Unobservable Inputs (Level 3) | Real Assets      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 0.1 0.1  
Significant Unobservable Inputs (Level 3) | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 0.0 $ 0.0