Regulatory Matters (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($) MW	Dec. 31, 2023 USD ($)	May 31, 2021
Regulatory Matters [Line Items]
Approved increase to basic rates and charges	$ 71,000
Total current regulatory assets	126,470	$ 89,419
Total long-term regulatory assets	474,963	541,784
Total current regulatory liabilities	8,322	23,371
Total long-term regulatory liabilities	$ 443,691	$ 527,224
Preferred Resource Portfolio Coal-Fired Generation Retirement MW by 2023	630
Public Utilities, Approved Return on Equity, Percentage	9.90%
Public Utilities, Approved Debt Capital Structure, Percentage	4.90%
Hoosier Wind Project MW	106
Subsidiary, Ownership Percentage, Parent	100.00%
Payments to Acquire Businesses, Gross	$ 92,600
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	48,800
Public Utilities, Rate Bases	3,500,000
Earnings from Tax Attributes	$ 21,400
Pike Co BESS Project MW	200
Pike Co BESS Project MwH	800
Expected added generation capability | MW	1,300
Crossvine Project | MW	85
Crossvine Project Storage Capacity | MW	85
Crossvine Project MwH | MW	340
Petersburg Unit 1 retired MW			230