Debt	9 Months Ended
Debt	Sep. 30, 2025
Debt Disclosure [Abstract]
Debt	Debt. a)Department of Energy Loan Guarantee: In connection with the development and construction of Vogtle Units No. 3 and No. 4, we and the Department of Energy and the Federal Financing Bank entered into a series of agreements pursuant to which we borrowed $4,633,028,000. As of September 30, 2025, we have repaid $681,973,000 of principal on the notes related to these borrowings and the aggregate Department of Energy-guaranteed borrowings outstanding, including capitalized interest, totaled $3,951,055,000. The final maturity date is February 20, 2044. b)Rural Utilities Service Guaranteed Loans: For the nine-month period ended September 30, 2025, we received advances on Rural Utilities Service-guaranteed Federal Financing Bank loans totaling $124,298,000 for long-term financing of general and environmental improvements at existing plants. c)Green First Mortgage Bonds: In January 2025, we issued $350,000,000 of 5.900% green first mortgage bonds, Series 2025A, to provide for long-term financing or refinancing of expenditures related to Vogtle Units No. 3 and No. 4, including refinancing principal payments on our Department of Energy-guaranteed loans that were made prior to Vogtle Unit No. 4's in-service date. In conjunction with the issuance of the bonds, we repaid $254,463,000 of outstanding commercial paper. The bonds are due to mature in February 2055 and are secured under our first mortgage indenture. d)Pollution Control Revenue Bonds: In February 2025, we remarketed $312,760,000 of term-rate pollution control revenue bonds that were issued on our behalf by the Development Authorities of Appling, Burke and Monroe Counties which were subject to mandatory tender at that time. This included $272,230,000 of Burke and Monroe bonds which we remarketed as five-year term-rate bonds at a rate of 3.60% through February 2030, and $40,530,000 of Series 2013A Appling bonds, which we converted to a variable weekly rate mode without external credit or liquidity support. In the weekly rate mode, bondholders may tender their bonds for purchase at any time upon at least seven days' notice, and we made an election under these bonds that obligates us to pay the purchase price of the bonds tendered for purchase that are not remarketed. Since the Series 2013A Appling bonds now contain a provision that could accelerate their payment to the current year under certain circumstances, at December 31, 2024, we reclassified these bonds from the Long-term debt line item to the Long-term debt and finance leases due within one year line item within our consolidated balance sheets. Our obligation to pay the principal and interest on all these pollution control bonds is secured under our first mortgage indenture, and additionally, our obligation to pay the purchase price on the Series 2013A Appling bonds is also secured under our first mortgage indenture.

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

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OGLETHORPE POWER CORP 10-Q