Revenue Recognition (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 2,916.6	$ 2,607.3	$ 3,304.2
Provision for Rate Refund and Tax Refund
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(3.0)	2.0	(1.2)
Integrated Market
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	74.5	71.6	163.8
Transmission
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	152.9	143.0	131.7
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	29.5	41.6	20.8
Residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,116.4	1,008.6	1,272.6
Commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	816.5	666.7	796.4
Industrial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	248.6	235.2	322.1
Oilfield
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	225.7	210.0	306.3
Public Authority and Street Light
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	255.5	228.6	291.7
System Sales Revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 2,662.7	$ 2,349.1	$ 2,989.1