Business Segments (Schedule of Revenue, By Products and Services) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 23,868	$ 25,079	$ 24,521
Electric Utilities and Infrastructure
Segment Reporting Information [Line Items]
Revenues	21,687	22,798	22,242
Gas Utilities and Infrastructure
Segment Reporting Information [Line Items]
Revenues	1,653	1,770	1,783
Commercial Renewables
Segment Reporting Information [Line Items]
Revenues	502	487	477
Total Reportable Segments
Segment Reporting Information [Line Items]
Revenues	23,842	25,055	24,502
Retail Electric
Segment Reporting Information [Line Items]
Revenues	18,898	19,745	19,013
Retail Electric | Electric Utilities and Infrastructure
Segment Reporting Information [Line Items]
Revenues	18,898	19,745	19,013
Wholesale Electric
Segment Reporting Information [Line Items]
Revenues	2,312	2,620	2,720
Wholesale Electric | Electric Utilities and Infrastructure
Segment Reporting Information [Line Items]
Revenues	1,878	2,231	2,345
Wholesale Electric | Commercial Renewables
Segment Reporting Information [Line Items]
Revenues	434	389	375
Retail Natural Gas
Segment Reporting Information [Line Items]
Revenues	1,691	1,782	1,817
Retail Natural Gas | Gas Utilities and Infrastructure
Segment Reporting Information [Line Items]
Revenues	1,691	1,782	1,817
Other
Segment Reporting Information [Line Items]
Revenues	1,069	1,037	1,081
Other | Electric Utilities and Infrastructure
Segment Reporting Information [Line Items]
Revenues	944	855	915
Other | Gas Utilities and Infrastructure
Segment Reporting Information [Line Items]
Revenues	57	84	64
Other | Commercial Renewables
Segment Reporting Information [Line Items]
Revenues	68	98	102
Operating Segments | Electric Utilities and Infrastructure
Segment Reporting Information [Line Items]
Revenues	21,720	22,831	22,273
Operating Segments | Gas Utilities and Infrastructure
Segment Reporting Information [Line Items]
Revenues	1,748	1,866	1,881
Operating Segments | Commercial Renewables
Segment Reporting Information [Line Items]
Revenues	502	487	477
Operating Segments | Total Reportable Segments
Segment Reporting Information [Line Items]
Revenues	$ 23,970	$ 25,184	$ 24,631