Revenue - Schedule of Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 944,955	$ 783,531
Regulatory cost recovery revenue	23,000	12,000
Retail Electric Service | Residential
Disaggregation of Revenue [Line Items]
Total operating revenues	409,724	367,346
Retail Electric Service | Non-Residential
Disaggregation of Revenue [Line Items]
Total operating revenues	406,137	359,516
Wholesale Energy Sales
Disaggregation of Revenue [Line Items]
Total operating revenues	95,603	28,903
Transmission Services for Others
Disaggregation of Revenue [Line Items]
Total operating revenues	31,791	25,492
Other Sources
Disaggregation of Revenue [Line Items]
Total operating revenues	1,700	2,274
Electric and Transmission Service
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 922,000	$ 772,000