Pending Acquisition (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
	Dec. 17, 2025	Nov. 06, 2025	Dec. 31, 2026	Dec. 31, 2025	Dec. 31, 2024	Sep. 30, 2025
Business Combination [Line Items]
Common stock, par value (in dollars per share)				$ 1		$ 1
Net Proceeds from Common Stock Sale				$ 347,106	$ 0
Sale of Common Stock
Business Combination [Line Items]
Common stock issued from sale of common stock (in shares)	4,402,513			4,402,513
Common stock, par value (in dollars per share)	$ 1.00
Per share or per unit amount of equity securities issued (in dollars per share)	$ 79.50
Net Proceeds from Common Stock Sale	$ 338,600
Vectren Energy Delivery of Ohio, LLC | Term Loan Facility, Commitment Letter
Business Combination [Line Items]
Debt instrument, term		364 days
Forecast | Vectren Energy Delivery of Ohio, LLC
Business Combination [Line Items]
Total consideration			$ 2,620,000
Payments to acquire businesses, gross			1,420,000
Forecast | Vectren Energy Delivery of Ohio, LLC | Promissory Note
Business Combination [Line Items]
Long-term debt, face amount			$ 1,200,000
Debt instrument, term			364 days
Interest rate (in percent)			6.50%