Revenue - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 1,820,741	$ 1,768,801	$ 4,211,772	$ 4,029,507
Wholesale Energy Sales
Disaggregation of Revenue [Line Items]
Total Operating Revenues	46,333	39,303	89,050	76,428
Transmission Services for Others
Disaggregation of Revenue [Line Items]
Total Operating Revenues	44,284	38,705	101,827	93,958
Other Sources
Disaggregation of Revenue [Line Items]
Total Operating Revenues	1,691	2,592	12,978	8,716
Residential | Retail Electric Service
Disaggregation of Revenue [Line Items]
Total Operating Revenues	963,186	966,557	2,063,775	2,057,407
Non-Residential | Retail Electric Service
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 765,247	$ 721,644	$ 1,944,142	$ 1,792,998