Regulatory Matters (Details) $ in Millions	9 Months Ended
Sep. 30, 2026 USD ($)	Dec. 31, 2025 USD ($)
Regulatory assets, non-current	$ 103.6	$ 137.4
Schedule of Regulatory Assets and Liabilities [Text Block]	REGULATORY MATTERS AES Ohio ESPs and Smart Grid Plans AES Ohio ESP Appeal From November 1, 2017 through December 18, 2019, AES Ohio operated pursuant to an approved ESP plan, which was initially approved on October 20, 2017 (“ESP 3”). On December 18, 2019, the PUCO approved AES Ohio's Notice of Withdrawal of ESP 3 and reversion to its prior rate plan (“ESP 1”). Among other items, the PUCO Order approving the ESP 1 rate plan included reinstating the non-bypassable RSC Rider, which provided annual revenue of approximately $79.0 million. The OCC has appealed to the Ohio Supreme Court the PUCO’s decision approving the reversion to ESP 1 as well as argued for a refund of the RSC revenue dating back to August 2021. Oral arguments regarding this appeal were held on April 22, 2025, and a court decision is pending. Smart Grid Comprehensive Settlement On October 23, 2020, AES Ohio entered into a Stipulation and Recommendation with the staff of the PUCO, various customers and organizations representing customers of AES Ohio and certain other parties with respect to, among other matters, AES Ohio's applications for (i) approval of AES Ohio's plan to modernize its distribution grid (“Smart Grid Phase 1”), (ii) findings that AES Ohio passed the SEET for 2018 and 2019, and (iii) findings that AES Ohio's ESP 1 satisfies the SEET and the more favorable in the aggregate (“MFA”) regulatory test. On June 16, 2021, the PUCO issued its opinion and order accepting the stipulation as filed. The OCC appealed the final PUCO Order with respect to the 2018 and 2019 SEET to the Ohio Supreme Court on December 6, 2021. On August 22, 2025, the Ohio Supreme Court reversed the PUCO's opinion and order with respect to the methodology used by the PUCO to support its findings related to the 2018 and 2019 SEET, and remanded the case to the PUCO to conduct further analysis of the SEET for those years. The PUCO held an evidentiary hearing on this issue on October 28 and 29, 2025, and on July 8, 2026, the PUCO ordered AES Ohio to issue refunds totaling $11.1 million via one-time bill credits which were issued during the third quarter of 2026. On October 5, 2026, the OCC filed an application for rehearing with the PUCO. The PUCO is expected to address the request by November 4, 2026. Distribution Rate Cases Ohio Energy Legislation and Three-Year Rate Plan ("TYRP") On April 30, 2025, the Ohio legislature passed new energy legislation (“House Bill 15”) that was signed by the Governor and became effective August 14, 2025. The legislation allows Ohio’s electric utilities to file three-year forecasted base distribution rate cases, which would replace ESPs and incorporate associated recovery riders. Among other provisions, the legislation eliminated as of its effective date, the LGR, which previously allowed for recovery of net OVEC costs and revenues. Changes to the regulatory framework from this legislation, including the recovery of future net OVEC costs and revenues, could be material to our results of operations, financial condition and cash flows. To comply with House Bill 15, AES Ohio filed an application with the PUCO on November 10, 2025 to establish a TYRP. This plan describes the investments necessary to strengthen and modernize AES Ohio's infrastructure and expand support for its customers. On July 21, 2026, AES Ohio entered into an unopposed Stipulation and Recommendation (the “TYRP Settlement”) with intervening parties and the Staff of the PUCO. The TYRP Settlement provides for base rates for electric distribution service customers in AES Ohio’s service territory in 2027, 2028, and 2029, with annual true-up proceedings, and is subject to, and conditioned upon, approval by the PUCO. Along with setting updated rates, the TYRP Settlement, if approved, would: •Establish a revenue requirement, subject to annual true up, of $622.5 million in 2027, $656.1 million in 2028, and $679.3 million in 2029 for AES Ohio's base rates for electric distribution service; and •Provide for a return on equity of 9.5%, subject to annual performance metrics, and a forecasted cost of long-term debt, subject to annual true-up, of 4.79% in 2027, 4.98% in 2028, and 5.08% in 2029 on a forecasted rate base of $1,801.8 million in 2027, $1,960.9 million in 2028, and $2,083.3 million in 2029, inclusive of certain assets that are currently recovered through the existing DIR and IIR, and based on a forecasted capital structure, subject to annual true-up with the equity layer capped at the forecasted amounts, of 53.37% equity and 46.63% long-term debt in 2027, 52.00% equity and 48.00% long-term debt in 2028, and 50.50% equity and 49.50% long-term debt in 2029. The evidentiary hearing was held on August 4, 2026, and AES Ohio anticipates a final order from the PUCO by the end of 2026. AES Ohio Merger Application Subject to the terms of the Merger Agreement as described in Note 1. Overview and Summary of Significant Accounting Policies - Proposed AES Merger, AES, Parent, and Merger Sub are required to use reasonable best efforts to obtain all required regulatory approvals, including regulatory approval from the PUCO. On April 10, 2026, AES Ohio submitted its required merger application to the PUCO, and on September 17, 2026, the PUCO approved the application. The OCC filed a motion for rehearing of the approval, arguing that the approval should have included an investment-grade credit rating maintenance requirement and ring-fencing requirement, which AES Ohio responded to on October 29, 2026. The PUCO's approval order remains operative.
Capital Structure - Equity - Three-Year Rate Plan (2027)	0.5337
Capital Structure - Equity - Three-Year Rate Plan (2028)	0.4663
Capital Structure - Equity - Three-Year Rate Plan (2028)	0.5200
Capital Structure - Long-term Debt - Three-Year Rate Plan (2028)	0.4800
Capital Structure - Equity - Three-Year Rate Plan (2029)	0.5050
Capital Structure - Long-term Debt - Three-Year Rate Plan (2029)	0.4950
Public Utilities, General Disclosures [Line Items]
SEET Refund	$ 11.1
Subsidiaries [Member]
Revenue Requirement - TYRP	622.5
Revenue Requirement - TYRP (2028)	656.1
Revenue Requirement - TYRP (2029)	$ 679.3
Return on Equity - Three-Year Rate Plan	0.095
Cost of Long-term Debt - Three-Year Rate Plan	4.79%
Cost of Long-term Debt - Three-Year Rate Plan (2028)	0.0498
Cost of Long-term Debt - Three-Year Rate Plan	0.0508
Rate Base - Three-Year Rate Plan (2027)	$ 1,801.8
Rate Base - Three-Year Rate Plan (2028)	1,960.9
Rate Base - Three-Year Rate Plan (2029)	2,083.3
Public Utilities, General Disclosures [Line Items]
RSC Rider	$ 79.0

Regulatory Matters (Details)
$ in Millions

9 Months Ended

Sep. 30, 2026

USD ($)

Dec. 31, 2025

USD ($)

Regulatory assets, non-current

$ 103.6

$ 137.4

Schedule of Regulatory Assets and Liabilities [Text Block]

REGULATORY MATTERS

AES Ohio ESPs and Smart Grid Plans

AES Ohio ESP Appeal

From November 1, 2017 through December 18, 2019, AES Ohio operated pursuant to an approved ESP plan, which was initially approved on October 20, 2017 (“ESP 3”). On December 18, 2019, the PUCO approved AES Ohio's Notice of Withdrawal of ESP 3 and reversion to its prior rate plan (“ESP 1”). Among other items, the PUCO Order approving the ESP 1 rate plan included reinstating the non-bypassable RSC Rider, which provided annual revenue of approximately $79.0 million. The OCC has appealed to the Ohio Supreme Court the PUCO’s decision approving the reversion to ESP 1 as well as argued for a refund of the RSC revenue dating back to August 2021. Oral arguments regarding this appeal were held on April 22, 2025, and a court decision is pending.

Smart Grid Comprehensive Settlement

On October 23, 2020, AES Ohio entered into a Stipulation and Recommendation with the staff of the PUCO, various customers and organizations representing customers of AES Ohio and certain other parties with respect to, among other matters, AES Ohio's applications for (i) approval of AES Ohio's plan to modernize its distribution grid (“Smart Grid Phase 1”), (ii) findings that AES Ohio passed the SEET for 2018 and 2019, and (iii) findings that AES Ohio's ESP 1 satisfies the SEET and the more favorable in the aggregate (“MFA”) regulatory test. On June 16, 2021, the PUCO issued its opinion and order accepting the stipulation as filed. The OCC appealed the final PUCO Order with respect to the 2018 and 2019 SEET to the Ohio Supreme Court on December 6, 2021. On August 22, 2025, the Ohio Supreme Court reversed the PUCO's opinion and order with respect to the methodology used by the PUCO to support its findings related to the 2018 and 2019 SEET, and remanded the case to the PUCO to conduct further analysis of the SEET for those years. The PUCO held an evidentiary hearing on this issue on October 28 and 29, 2025, and on July 8, 2026, the PUCO ordered AES Ohio to issue refunds totaling $11.1 million via one-time bill credits which were issued during the third quarter of 2026. On October 5, 2026, the OCC filed an application for rehearing with the PUCO. The PUCO is expected to address the request by November 4, 2026.

Distribution Rate Cases

Ohio Energy Legislation and Three-Year Rate Plan ("TYRP")

On April 30, 2025, the Ohio legislature passed new energy legislation (“House Bill 15”) that was signed by the Governor and became effective August 14, 2025. The legislation allows Ohio’s electric utilities to file three-year forecasted base distribution rate cases, which would replace ESPs and incorporate associated recovery riders. Among other provisions, the legislation eliminated as of its effective date, the LGR, which previously allowed for recovery of net OVEC costs and revenues. Changes to the regulatory framework from this legislation, including the recovery of future net OVEC costs and revenues, could be material to our results of operations, financial condition and cash flows.

To comply with House Bill 15, AES Ohio filed an application with the PUCO on November 10, 2025 to establish a TYRP. This plan describes the investments necessary to strengthen and modernize AES Ohio's infrastructure and expand support for its customers. On July 21, 2026, AES Ohio entered into an unopposed Stipulation and Recommendation (the “TYRP Settlement”) with intervening parties and the Staff of the PUCO. The TYRP Settlement provides for base rates for electric distribution service customers in AES Ohio’s service territory in 2027, 2028, and 2029, with annual true-up proceedings, and is subject to, and conditioned upon, approval by the PUCO. Along with setting updated rates, the TYRP Settlement, if approved, would:

•Establish a revenue requirement, subject to annual true up, of $622.5 million in 2027, $656.1 million in 2028, and $679.3 million in 2029 for AES Ohio's base rates for electric distribution service; and

•Provide for a return on equity of 9.5%, subject to annual performance metrics, and a forecasted cost of long-term debt, subject to annual true-up, of 4.79% in 2027, 4.98% in 2028, and 5.08% in 2029 on a forecasted rate base of $1,801.8 million in 2027, $1,960.9 million in 2028, and $2,083.3 million in 2029, inclusive of certain assets that are currently recovered through the existing DIR and IIR, and based on a forecasted capital structure, subject to annual true-up with the equity layer capped at the forecasted

amounts, of 53.37% equity and 46.63% long-term debt in 2027, 52.00% equity and 48.00% long-term debt in 2028, and 50.50% equity and 49.50% long-term debt in 2029.

The evidentiary hearing was held on August 4, 2026, and AES Ohio anticipates a final order from the PUCO by the end of 2026.

AES Ohio Merger Application

Subject to the terms of the Merger Agreement as described in Note 1. Overview and Summary of Significant Accounting Policies - Proposed AES Merger, AES, Parent, and Merger Sub are required to use reasonable best efforts to obtain all required regulatory approvals, including regulatory approval from the PUCO. On April 10, 2026, AES Ohio submitted its required merger application to the PUCO, and on September 17, 2026, the PUCO approved the application. The OCC filed a motion for rehearing of the approval, arguing that the approval should have included an investment-grade credit rating maintenance requirement and ring-fencing requirement, which AES Ohio responded to on October 29, 2026. The PUCO's approval order remains operative.

Capital Structure - Equity - Three-Year Rate Plan (2027)

0.5337

Capital Structure - Equity - Three-Year Rate Plan (2028)

0.4663

Capital Structure - Equity - Three-Year Rate Plan (2028)

0.5200

Capital Structure - Long-term Debt - Three-Year Rate Plan (2028)

0.4800

Capital Structure - Equity - Three-Year Rate Plan (2029)

0.5050

Capital Structure - Long-term Debt - Three-Year Rate Plan (2029)

0.4950