v3.26.1
Postretirement Benefit Plans (Debt Securities, Trading, and Equity Securities, FV-NI) (Details) - USD ($)
$ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Defined Benefit Plan Disclosure [Line Items]    
Adjusted Cost $ 4.2 $ 4.2
Unrealized Gains 0.5 0.7
Unrealized Losses 0.0 (0.1)
Fair Value 4.7 4.8
Level 1 Securities:    
Defined Benefit Plan Disclosure [Line Items]    
Adjusted Cost 4.2 4.1
Unrealized Gains 0.5 0.7
Unrealized Losses 0.0 (0.1)
Fair Value $ 4.7 4.7
Level 2 Securities:    
Defined Benefit Plan Disclosure [Line Items]    
Adjusted Cost   0.1
Unrealized Gains   0.0
Unrealized Losses   0.0
Fair Value   $ 0.1