v3.26.3
Equity (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Jun. 30, 2026
Mar. 31, 2026
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Sep. 30, 2026
Sep. 30, 2025
Apr. 30, 2026
Dec. 31, 2025
Apr. 04, 2025
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.

Agreement to Sell Minority Interest in AES Ohio
On April 4, 2025, DPL sold an aggregate indirect equity interest in AES Ohio of approximately 30% to Astrid Holdings LP, a wholly-owned subsidiary of La Caisse, for total proceeds of approximately $544.0 million, resulting in an increase to Redeemable stock of subsidiaries of $537.5 million, net of transaction costs, on the Condensed Consolidated Balance Sheets. The transaction also resulted in reclassification of $2.7 million of pension related AOCL to Member's equity. There is no change in management or operational control of DPL or AES Ohio as a result of the transaction. As DPL maintained control after the transaction, AES Ohio continues to be consolidated by DPL.

The shareholders' agreements with La Caisse contain certain redemption features that, while not currently in effect, are not solely in DPL's control. As a result, the noncontrolling ownership interest is considered temporary equity. The Company has concluded that the likelihood of an event that would allow La Caisse to redeem its interest under the terms of the shareholders' agreements is remote, but would require redemption at fair value. Therefore, as of September 30, 2026, the noncontrolling ownership interest is not probable of becoming redeemable and subsequent adjustments to the carrying value were not required.

Prior to the transaction closing, DPL contributed to AES Ohio Holdings, Inc. (“Ohio Holdings”) 100% of the issued and outstanding shares of AES Ohio, such that Ohio Holdings owns 100% of AES Ohio.
AOCI/(AOCL)
The changes in the components of AOCI during the nine months ended September 30, 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
(0.7)
— 
(0.7)
Balance as of September 30, 2026
$
16.7 
$
(1.7)
$
15.0 
        
Proceeds from Contributions from Parent   $ 87.5         $ 87.5 $ 0.0      
Proceeds from Issuance of Redeemable Convertible Preferred Stock             0.0 539.7      
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest       $ 401.5       401.5      
Members' Equity, Total $ 556.6 530.8 $ 439.4   $ 393.4   556.6     $ 412.9  
Other Comprehensive Income (Loss), Net of Tax (0.1)     (0.1)     (0.3) (0.1)      
CDPQ Investment total                     $ 544.0
Proceeds from Noncontrolling Interests         537.5            
Net Income (Loss) Attributable to Parent 26.0 4.2 26.6 8.3 0.7 $ 2.7 56.8 11.7      
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest (12.6) (3.1) (12.7) (5.1) (1.6)   (28.4) (6.7)      
Redeemable Noncontrolling Interest, Equity, Carrying Amount 652.0 643.8 605.2 588.7 $ 584.3   652.0 588.7   594.7  
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax (0.2) (0.3) $ (0.2) (0.2)     (0.7) (0.6)      
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax             (0.7)        
Accumulated other comprehensive income 15.0           15.0     15.7  
Equity Contribution From Parent                 $ 87.5    
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax 16.7           16.7     17.4  
Other Comprehensive Income (Loss), Defined Benefit Plan, Transition Asset (Obligation), Reclassification Adjustment from AOCI, after Tax 0.1     0.1     0.4 0.5      
Ohio Holdings                      
Subsidiary, Ownership Percentage, Parent         100.00%            
AOCI Attributable to Parent [Member]                      
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent         $ 2.7            
Defined Benefit Plan Attributable to Parent                      
Other Comprehensive Income (Loss), Defined Benefit Plan, Transition Asset (Obligation), Reclassification Adjustment from AOCI, after Tax             0.0        
AOCI, Unfunded Pension and Other Postretirement Obligations $ (1.7)           $ (1.7)     $ (1.7)  
Other Additional Capital [Member]                      
Proceeds from Contributions from Parent   $ 87.5                  
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest       $ 0.0       $ 0.0