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No definition available.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Amount of revenue that is not accounted for under Topic 606.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 415.4	$ 404.1	$ 801.7	$ 850.8
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	423.4	410.5	818.4	864.6
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	257.2	271.7	507.1	575.2
Retail \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	84.8	70.4	157.7	158.5
Retail \| Commercial and industrial (C&I)
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	163.7	191.4	332.8	397.2
Retail \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	8.7	9.9	16.6	19.5
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	81.6	72.0	154.8	156.8
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	76.0	60.0	138.6	117.4
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0.6	0.4	1.2	1.4
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 8.0	$ 6.4	$ 16.7	$ 13.8