Operating Revenues - Other Non-Utility Operating Revenues (Details) - Revenues from contracts with customers - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Operating Revenues
Revenues from contracts with customers	$ 8,235.7	$ 7,169.3	$ 7,449.3
Other non-utility revenues
Disaggregation of Operating Revenues
Revenues from contracts with customers	101.5	76.3	70.2
Other non-utility revenues | We Power revenues
Disaggregation of Operating Revenues
Revenues from contracts with customers	23.3	22.9	25.4
Other non-utility revenues | Other
Disaggregation of Operating Revenues
Revenues from contracts with customers	0.1	1.7	4.2
Transferred over time | Other non-utility revenues | Wind generation revenues
Disaggregation of Operating Revenues
Revenues from contracts with customers	60.3	34.6	24.0
Transferred over time | Other non-utility revenues | Appliance service repairs
Disaggregation of Operating Revenues
Revenues from contracts with customers	$ 17.8	$ 17.1	$ 16.6