Rate Matters and Regulation	3 Months Ended
Mar. 31, 2024
Regulated Operations [Abstract]
Rate Matters and Regulation	13. Rate Matters and Regulation Except as disclosed below, the circumstances set forth in Note 14 to the financial statements included in the Registrants' 2023 Form 10-K appropriately represent, in all material respects, the current status of the Registrants' regulatory matters. Completed Regulatory Matters Integrated Resource Plans OG&E has conducted technical conferences for stakeholder engagement on its draft triennial IRP and, on March 29, 2024, issued its final 2024 IRP to the OCC and APSC. This 2024 IRP identified capacity needs of 556, 431 and 1,096 MWs in 2026, 2027 and 2028, respectively. The IRP assumes that Horseshoe Lake unit 7 will be retired in 2024, Tinker units 5A and 5B will be retired in 2025, and Horseshoe Lake unit 8 will be retired in 2027. The IRP also provides that OG&E will issue requests for proposals, beginning in the second quarter of 2024, for resources to meet the capacity needs identified in the IRP while maintaining affordability and reliability for OG&E’s customers. APSC Proceedings 2023 Formula Rate Plan Filing In October 2023, OG&E filed its final evaluation report under its Formula Rate Plan, and on January 30, 2024, OG&E and the APSC Staff filed an uncontested joint settlement agreement, which included an annual electric revenue increase of $3.5 million. On March 7, 2024, the APSC issued a final order approving the uncontested settlement agreement, and new rates became effective April 1, 2024. OCC Proceedings 2022 Oklahoma Fuel Prudency In June 2023, the Public Utility Division Staff filed their application initiating the review of the 2022 fuel adjustment clause and prudence review. The OCC issued an order on April 11, 2024 finding that OG&E's 2022 fuel costs and generation operations were prudent. Pending Regulatory Matters Various proceedings pending before state or federal regulatory agencies are described below. Unless stated otherwise, the Registrants cannot predict when the regulatory agency will act or what action the regulatory agency will take. The Registrants' financial results are dependent in part on timely and constructive decisions by the regulatory agencies that set OG&E's rates. APSC Proceedings Capacity Power Purchase Agreement Cost Recovery On October 4, 2023, OG&E filed an application at the APSC seeking approval of a methodology for recovery of capacity costs associated with short-term power purchase agreements entered into to meet capacity needs in each of the years between 2023 and 2027. On December 29, 2023, the Administrative Law Judge issued an order authorizing OG&E to defer to a regulatory asset its capacity costs associated with short-term power purchase agreements for 2023, along with a carrying charge at the commission-approved customer deposit interest rate. The order requires OG&E and the parties to address treatment for any expenses beyond the calendar year 2023. The parties have agreed to a procedural schedule that involves additional rounds of testimony and a hearing in August 2024. Arkansas 2024 Generation Construction Notice Filing On January 19, 2024, OG&E filed an application seeking APSC approval to begin construction of 96 megawatts of combustion turbines at Tinker Air Force Base. A public hearing is scheduled for June 25, 2024, and a decision is expected by the end of August 2024. FERC Proceedings Order for Sponsored Transmission Upgrades within SPP Under Attachment Z2 of the SPP Open Access Transmission Tariff, costs of participant-funded, or "sponsored," transmission upgrades may be recovered from other SPP customers whose transmission service depends on capacity enabled by the upgrade. The SPP Tariff required the SPP to charge for these upgrades beginning in 2008, but the SPP did not begin charging its customers for these upgrades until 2016 due to information system limitations. At that time, the SPP sought a waiver of a time limitation in its tariff that otherwise would have prevented it from waiting until 2016 to bill for the 2008 through 2015 period. The FERC granted the waiver, and the SPP then billed OG&E as a user for these Z2 charges while simultaneously crediting OG&E as a sponsor of Z2 transmission upgrades, resulting in OG&E being a net recipient of sponsored upgrade credits. The majority of these net credits were refunded to customers through OG&E's various rate riders that include SPP activity with the remaining amounts retained by OG&E. Several companies that were net payers of Z2 charges sought rehearing of the FERC's 2016 order approving the waiver and then appealed it. While that appeal was pending, the FERC obtained a remand and then reversed itself and ruled that the SPP tariff provision that prohibited the 2008 through 2015 charges could not be waived. It ordered the SPP to develop a plan to refund the payments but not to implement the refunds until further ordered to do so. In response, in April 2019, OG&E filed a request for rehearing at the FERC. The next month, it also filed a Complaint at the FERC against the SPP contending that the SPP and not OG&E should bear the cost of any refunds resulting from the SPP's tariff violation and that SPP’s actions also violated its contracts with OG&E. In February 2020, the FERC denied OG&E's request for rehearing but did not consider SPP's refund plan. No date for payment of refunds was established. In August 2021, the U.S. Court of Appeals for the District of Columbia Circuit denied OG&E's petition for review of the FERC's order denying the waiver and requiring refunds. After denying rehearing of its ruling, the court of appeals returned the matter in November 2021 to the FERC for further proceedings in accordance with its opinion. The FERC has not acted on that remand. If the FERC proceeds to order refunds in full, OG&E estimates it would be required to refund $13.0 million, which is net of amounts paid to other utilities for upgrades and would be subject to interest at the FERC-approved rate. The SPP has stated in filings with the FERC both before and after the court of appeals decision that there are considerable complexities in implementing the refunds that will have to be resolved before they can be paid. Payment of refunds would shift recovery of these upgrade credits to future periods. The SPP filed a report on January 4, 2022 confirming that administering refunds would be complex and could take years unless the SPP is allowed to make certain simplifying assumptions. The SPP also urged that all pending complaint proceedings, including OG&E's complaint and three similar complaints against the SPP, be resolved before any refund process is ordered to begin. OG&E and other parties filed responses to the SPP report, and the matter remains pending at the FERC. Of the $13.0 million, the Registrants would be impacted by $5.0 million in expense that initially benefited the Registrants in 2016, and OG&E customers would incur a net impact of $8.0 million in expense through rider mechanisms or the FERC formula rate. As of March 31, 2024, the Registrants have reserved $13.0 million plus estimated interest for a potential refund. In November 2022, the FERC issued an order denying OG&E's complaint against the SPP. It also issued orders granting the other three complaints against the SPP in part but awarded no relief. All four complainants timely sought rehearing of these orders. On June 27, 2023, the FERC made final its orders granting in part complaints filed against the SPP by OG&E and three other project sponsors (or groups thereof) on claims arising from the SPP’s failure to implement Attachment Z2 so that project sponsors could be paid as required under the tariff, but awarding no relief. OG&E and the other complainants have appealed to the U.S. Court of Appeals for the Eighth Circuit, where the matter was briefed and oral arguments were heard on March 14, 2024. It will likely be decided in the summer of 2024. In June 2020, the FERC approved, effective July 1, 2020, an SPP proposal to eliminate Attachment Z2 revenue crediting and replace it with a different rate mechanism that would provide project sponsors, such as OG&E, the same level of recovery. This elimination of the Attachment Z2 revenue crediting would only prospectively impact OG&E and its recovery of any future upgrade costs that it may incur as a project sponsor subsequent to July 2020. All of the existing projects that are eligible to receive revenue credits under Attachment Z2 will remain eligible, which includes the $13.0 million that is at issue in the remand from OG&E's appeal and in OG&E's complaint proceeding. OCC Proceedings Oklahoma Retail Electric Supplier Certified Territory Act Causes As previously disclosed, several rural electric cooperative electricity suppliers filed complaints with the OCC alleging that OG&E, because it was providing service to large loads in another supplier's territory, had violated the Oklahoma Retail Electric Supplier Certified Territory Act. OG&E believes it is lawfully serving customers under specific exemptions under this act that allow it to serve customers having a load of one megawatt or greater. There were five complaint cases initiated at the OCC, and the OCC issued decisions on each of them. The OCC ruled in favor of the electric cooperatives in three of those cases under statutory interpretation and ruled in favor of OG&E in two of those cases under injunctive theory. All five of those cases were appealed to the Oklahoma Supreme Court. On April 4, 2023, the Oklahoma Supreme Court issued its opinion which vacated the OCC's injunctions with respect to four of the cases and held that the Oklahoma Retail Electric Supplier Certified Territory Act does not limit the mechanism by which OG&E may provide service to large loads in another supplier's territory pursuant to the one megawatt exception. The one pending legal issue left for the Oklahoma Supreme Court to resolve is a statutory interpretation on how a supplier calculates "connected load for initial full operation" for purposes of the exemption under the act. If the Oklahoma Supreme Court ultimately were to find that the customers being served in this single case are not exempted from the Oklahoma Retail Electric Supplier Certified Territory Act, OG&E would have to evaluate the recoverability of some plant investments made to serve these customers and may also be required to reimburse the certified territory supplier in this case for an amount of lost revenue. Such amounts would not be expected to be material to the Registrants' results of operations. 2023 Oklahoma General Rate Review On December 29, 2023, OG&E filed a general rate review in Oklahoma seeking a rate increase of $332.5 million and a 10.5 percent return on equity based on a common equity percentage of 53.50 percent. The rate review seeks recovery of $1.3 billion of net capital investment since the last general rate review. A hearing on the merits is scheduled for June 17, 2024. SPP Proceedings Resource Capacity Accreditation In July 2022, the SPP Board of Directors approved a new unit accreditation methodology for conventional generation which requires submittal to and approval from the FERC prior to becoming effective. On March 2, 2023, the FERC rejected the SPP’s proposed capacity accreditation methodology for wind and solar generators. Following the FERC’s rejection, the SPP began an extensive review of both the methodology proposed for thermal resources which had not yet been submitted to the FERC, and the accreditation methodology for wind and solar generators. These methodologies were reviewed and approved by both the Regional State Committee and the SPP Board of Directors in late October 2023 and were submitted to the FERC for approval on February 23, 2024. If approved by the FERC, both methodologies are expected to be effective in 2026 and may contribute to OG&E’s incremental capacity needs.

Rate Matters and Regulation

3 Months Ended

Mar. 31, 2024

13. Rate Matters and Regulation

Except as disclosed below, the circumstances set forth in Note 14 to the financial statements included in the Registrants' 2023 Form 10-K appropriately represent, in all material respects, the current status of the Registrants' regulatory matters.

Completed Regulatory Matters

Integrated Resource Plans

OG&E has conducted technical conferences for stakeholder engagement on its draft triennial IRP and, on March 29, 2024, issued its final 2024 IRP to the OCC and APSC. This 2024 IRP identified capacity needs of 556, 431 and 1,096 MWs in 2026, 2027 and 2028, respectively. The IRP assumes that Horseshoe Lake unit 7 will be retired in 2024, Tinker units 5A and 5B will be retired in 2025, and Horseshoe Lake unit 8 will be retired in 2027. The IRP also provides that OG&E will issue requests for proposals, beginning in the second quarter of 2024, for resources to meet the capacity needs identified in the IRP while maintaining affordability and reliability for OG&E’s customers.

APSC Proceedings

2023 Formula Rate Plan Filing

In October 2023, OG&E filed its final evaluation report under its Formula Rate Plan, and on January 30, 2024, OG&E and the APSC Staff filed an uncontested joint settlement agreement, which included an annual electric revenue increase of $3.5 million. On March 7, 2024, the APSC issued a final order approving the uncontested settlement agreement, and new rates became effective April 1, 2024.

OCC Proceedings

2022 Oklahoma Fuel Prudency

In June 2023, the Public Utility Division Staff filed their application initiating the review of the 2022 fuel adjustment clause and prudence review. The OCC issued an order on April 11, 2024 finding that OG&E's 2022 fuel costs and generation operations were prudent.

Pending Regulatory Matters

Various proceedings pending before state or federal regulatory agencies are described below. Unless stated otherwise, the Registrants cannot predict when the regulatory agency will act or what action the regulatory agency will take. The Registrants' financial results are dependent in part on timely and constructive decisions by the regulatory agencies that set OG&E's rates.

APSC Proceedings

Capacity Power Purchase Agreement Cost Recovery

On October 4, 2023, OG&E filed an application at the APSC seeking approval of a methodology for recovery of capacity costs associated with short-term power purchase agreements entered into to meet capacity needs in each of the years between 2023 and 2027. On December 29, 2023, the Administrative Law Judge issued an order authorizing OG&E to defer to a regulatory asset its capacity costs associated with short-term power purchase agreements for 2023, along with a carrying charge at the commission-approved customer deposit interest rate. The order requires OG&E and the parties to address treatment for any expenses beyond the calendar year 2023. The parties have agreed to a procedural schedule that involves additional rounds of testimony and a hearing in August 2024.

Arkansas 2024 Generation Construction Notice Filing

On January 19, 2024, OG&E filed an application seeking APSC approval to begin construction of 96 megawatts of combustion turbines at Tinker Air Force Base. A public hearing is scheduled for June 25, 2024, and a decision is expected by the end of August 2024.

FERC Proceedings

Order for Sponsored Transmission Upgrades within SPP

Under Attachment Z2 of the SPP Open Access Transmission Tariff, costs of participant-funded, or "sponsored," transmission upgrades may be recovered from other SPP customers whose transmission service depends on capacity enabled by the upgrade. The SPP Tariff required the SPP to charge for these upgrades beginning in 2008, but the SPP did not begin charging its customers for these upgrades until 2016 due to information system limitations. At that time, the SPP sought a waiver of a time limitation in its tariff that otherwise would have prevented it from waiting until 2016 to bill for the 2008 through 2015 period. The FERC granted the waiver, and the SPP then billed OG&E as a user for these Z2 charges while simultaneously crediting OG&E as a sponsor of Z2 transmission upgrades, resulting in OG&E being a net recipient of sponsored upgrade credits. The majority of these net credits were refunded to customers through OG&E's various rate riders that include SPP activity with the remaining amounts retained by OG&E.

Several companies that were net payers of Z2 charges sought rehearing of the FERC's 2016 order approving the waiver and then appealed it. While that appeal was pending, the FERC obtained a remand and then reversed itself and ruled that the SPP tariff provision that prohibited the 2008 through 2015 charges could not be waived. It ordered the SPP to develop a plan to refund the payments but not to implement the refunds until further ordered to do so. In response, in April 2019, OG&E filed a request for rehearing at the FERC. The next month, it also filed a Complaint at the FERC against the SPP contending that the SPP and not OG&E should bear the cost of any refunds resulting from the SPP's tariff violation and that SPP’s actions also violated its contracts with OG&E. In February 2020, the FERC denied OG&E's request for rehearing but did not consider SPP's refund plan. No date for payment of refunds was established. In August 2021, the U.S. Court of Appeals for the District of Columbia Circuit denied OG&E's petition for review of the FERC's order denying the waiver and requiring refunds. After denying rehearing of its ruling, the court of appeals returned the matter in November 2021 to the FERC for further proceedings in accordance with its opinion. The FERC has not acted on that remand.

If the FERC proceeds to order refunds in full, OG&E estimates it would be required to refund $13.0 million, which is net of amounts paid to other utilities for upgrades and would be subject to interest at the FERC-approved rate. The SPP has stated in filings with the FERC both before and after the court of appeals decision that there are considerable complexities in implementing the refunds that will have to be resolved before they can be paid. Payment of refunds would shift recovery of these upgrade credits to future periods. The SPP filed a report on January 4, 2022 confirming that administering refunds would be complex and could take years unless the SPP is allowed to make certain simplifying assumptions. The SPP also urged that all pending complaint proceedings, including OG&E's complaint and three similar complaints against the SPP, be resolved before any refund process is ordered to begin. OG&E and other parties filed responses to the SPP report, and the matter remains pending at the FERC. Of the $13.0 million, the Registrants would be impacted by $5.0 million in expense that initially benefited the Registrants in 2016, and OG&E customers would incur a net impact of $8.0 million in expense through rider mechanisms or the FERC formula rate. As of March 31, 2024, the Registrants have reserved $13.0 million plus estimated interest for a potential refund.

In November 2022, the FERC issued an order denying OG&E's complaint against the SPP. It also issued orders granting the other three complaints against the SPP in part but awarded no relief. All four complainants timely sought rehearing of these orders. On June 27, 2023, the FERC made final its orders granting in part complaints filed against the SPP by OG&E and three other project sponsors (or groups thereof) on claims arising from the SPP’s failure to implement Attachment Z2 so that project sponsors could be paid as required under the tariff, but awarding no relief. OG&E and the other complainants have appealed to the U.S. Court of Appeals for the Eighth Circuit, where the matter was briefed and oral arguments were heard on March 14, 2024. It will likely be decided in the summer of 2024.

In June 2020, the FERC approved, effective July 1, 2020, an SPP proposal to eliminate Attachment Z2 revenue crediting and replace it with a different rate mechanism that would provide project sponsors, such as OG&E, the same level of recovery. This elimination of the Attachment Z2 revenue crediting would only prospectively impact OG&E and its recovery of any future upgrade costs that it may incur as a project sponsor subsequent to July 2020. All of the existing projects that are eligible to receive revenue credits under Attachment Z2 will remain eligible, which includes the $13.0 million that is at issue in the remand from OG&E's appeal and in OG&E's complaint proceeding.

OCC Proceedings

Oklahoma Retail Electric Supplier Certified Territory Act Causes

As previously disclosed, several rural electric cooperative electricity suppliers filed complaints with the OCC alleging that OG&E, because it was providing service to large loads in another supplier's territory, had violated the Oklahoma Retail Electric Supplier Certified Territory Act. OG&E believes it is lawfully serving customers under specific exemptions under this act that allow it to serve customers having a load of one megawatt or greater. There were five complaint cases initiated at the OCC, and the OCC issued decisions on each of them. The OCC ruled in favor of the electric cooperatives in three of those cases under statutory interpretation and ruled in favor of OG&E in two of those cases under injunctive theory. All five of those cases were appealed to the Oklahoma Supreme Court.

On April 4, 2023, the Oklahoma Supreme Court issued its opinion which vacated the OCC's injunctions with respect to four of the cases and held that the Oklahoma Retail Electric Supplier Certified Territory Act does not limit the mechanism by which OG&E may provide service to large loads in another supplier's territory pursuant to the one megawatt exception. The one pending legal issue left for the Oklahoma Supreme Court to resolve is a statutory interpretation on how a supplier calculates "connected load for initial full operation" for purposes of the exemption under the act. If the Oklahoma Supreme Court ultimately were to find that the customers being served in this single case are not exempted from the Oklahoma Retail Electric Supplier Certified Territory Act, OG&E would have to evaluate the recoverability of some plant investments made to serve these customers and may also be required to reimburse the certified territory supplier in this case for an amount of lost revenue. Such amounts would not be expected to be material to the Registrants' results of operations.

2023 Oklahoma General Rate Review

On December 29, 2023, OG&E filed a general rate review in Oklahoma seeking a rate increase of $332.5 million and a 10.5 percent return on equity based on a common equity percentage of 53.50 percent. The rate review seeks recovery of $1.3 billion of net capital investment since the last general rate review. A hearing on the merits is scheduled for June 17, 2024.

SPP Proceedings

Resource Capacity Accreditation

In July 2022, the SPP Board of Directors approved a new unit accreditation methodology for conventional generation which requires submittal to and approval from the FERC prior to becoming effective. On March 2, 2023, the FERC rejected the SPP’s proposed capacity accreditation methodology for wind and solar generators. Following the FERC’s rejection, the SPP began an extensive review of both the methodology proposed for thermal resources which had not yet been submitted to the FERC, and the accreditation methodology for wind and solar generators. These methodologies were reviewed and approved by both the Regional State Committee and the SPP Board of Directors in late October 2023 and were submitted to the FERC for approval on February 23, 2024. If approved by the FERC, both methodologies are expected to be effective in 2026 and may contribute to OG&E’s incremental capacity needs.