v3.26.1
Equity (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Apr. 30, 2026
Dec. 31, 2025
Dec. 31, 2024
Stockholders' Equity Note Disclosure
8. EQUITY

Contributions from AES
In April 2026, DPL received equity capital contributions from AES totaling $87.5 million. DPL then made the same investments in AES Ohio. The proceeds are primarily for funding needs related to AES Ohio's capital expenditure program.

AOCI/(AOCL)
The changes in the components of AOCI during the three months ended March 31, 2026 are as follows:

$ in millions
Change in cash flow hedges
Change in unfunded pension and other postretirement obligations
Total
Balance as of January 1, 2026
$
17.4 
$
(1.7)
$
15.7 
Amounts reclassified from AOCI to earnings
(0.2)
— 
(0.2)
Balance as of March 31, 2026
$
17.2 
$
(1.7)
$
15.5 
        
Stockholders' Equity, Other $ (0.1)        
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest   $ 364.8     $ 362.1
Members' Equity 3,049.3     $ 3,049.3  
Other Comprehensive Income (Loss), Net of Tax (0.1) 0.0      
Net Income (Loss) Attributable to Parent 26.6 2.7      
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest 12.7 0.0      
Redeemable Noncontrolling Interest, Equity, Carrying Amount 605.2     594.7  
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax (0.2) (0.2)      
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax (0.2)        
Accumulated other comprehensive income 15.5 (5.3)   15.7 (5.3)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax (0.2)        
Equity Contribution From Parent     $ 87.5    
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax 17.2     17.4  
Total change in unfunded pension obligation 0.0        
Defined Benefit Plan, Unfunded Plan          
Accumulated other comprehensive income $ (1.7)     $ (1.7)  
Operating Segments [Member] | Utility [Member]          
Net Income (Loss) Attributable to Parent   10.7      
Common Stock [Member]          
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest   $ 0.0     $ 0.0
Shares, Issued   1     1