Summary of Significant Accounting Policies Operating Revenues (Details) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2019	Dec. 31, 2019 USD ($) contract performance_obligations	Dec. 31, 2018 USD ($)
Upstream
Disaggregation of Operating Revenues
Number of years Upstream will receive fixed payment	10 years
Electric
Disaggregation of Operating Revenues
Number of performance obligations		1
Percent fuel costs can vary from the rate case approved costs before deferral is required		2.00%
Number of days payment is due		30 days
Electric | Wholesale
Disaggregation of Operating Revenues
Number of performance obligations		2
Number of contracts | contract		1
Natural gas
Disaggregation of Operating Revenues
Number of days payment is due		30 days
Other non-utility revenues | We Power revenues
Disaggregation of Operating Revenues
Revenues amortized from deferred revenue during the period | $		$ 25.4	$ 25.3
Other non-utility revenues | Appliance service repairs | Maximum
Disaggregation of Operating Revenues
Duration of contract for remaining performance obligations in contract		1 year
Other non-utility revenues | Wind generation revenues
Disaggregation of Operating Revenues
Number of performance obligations		1
Other non-utility revenues | Wind generation revenues | Upstream
Disaggregation of Operating Revenues
Number of years Upstream will receive fixed payment		10 years