Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

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- Definition

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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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-Section S99
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

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Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 526.1	$ 537.3	$ 1,376.9	$ 1,453.9
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	533.1	540.1	1,397.7	1,468.6
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	354.5	356.8	929.7	939.5
Retail \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	119.3	114.4	277.8	279.5
Retail \| Commercial and industrial (C&I)
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	222.4	229.4	619.6	626.0
Retail \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12.8	13.0	32.3	34.0
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	106.6	118.0	263.4	326.8
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	64.4	60.7	181.8	175.4
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0.6	1.8	2.0	12.2
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 7.0	$ 2.8	$ 20.8	$ 14.7