Revenues (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	$ 2,811	$ 3,141
Regulated Electric \| Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	2,203	2,325
Regulated Natural Gas \| Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	583	794
All Other \| Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	25	22
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,674	3,040
Total revenue from contracts with customers \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,086	2,237
Total revenue from contracts with customers \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	567	784
Total revenue from contracts with customers \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	21	19
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,327	2,668
Retail \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,042	1,231
Retail \| C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,255	1,404
Retail \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	30	33
Retail \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,771	1,899
Retail \| Regulated Electric \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	676	727
Retail \| Regulated Electric \| C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,066	1,140
Retail \| Regulated Electric \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	29	32
Retail \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	535	750
Retail \| Regulated Natural Gas \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	355	495
Retail \| Regulated Natural Gas \| C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	180	255
Retail \| Regulated Natural Gas \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Retail \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	21	19
Retail \| All Other \| Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11	9
Retail \| All Other \| C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9	9
Retail \| All Other \| Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	1
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	166	189
Wholesale \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	166	189
Wholesale \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Wholesale \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	132	131
Transmission \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	132	131
Transmission \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Transmission \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	49	52
Other \| Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	17	18
Other \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	32	34
Other \| All Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	137	101
Alternative revenue and other \| Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	117	88
Alternative revenue and other \| Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	16	10
Alternative revenue and other \| All Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 4	$ 3

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of revenue that is not accounted for under Topic 606.

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-Publisher FASB
-Name Accounting Standards Codification
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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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