Business Segments (Schedule of Revenue, By Products and Services) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Operating revenues	$ 5,559	$ 6,395	$ 5,708	$ 6,263	$ 5,610	$ 6,217	$ 5,393	$ 5,536	$ 23,925	$ 22,756	$ 17,912
Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									22,228	20,871	16,042
International Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues									1,417	1,546	1,549
Commercial Power [Member]
Segment Reporting Information [Line Items]
Operating revenues									255	254	299
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues									23,900	22,671	17,890
Retail Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues									19,007	17,837	13,773
Retail Electric [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									19,007	17,837	13,773
Wholesale Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues									3,460	3,427	2,871
Wholesale Electric [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									1,879	1,720	1,120
Wholesale Electric [Member] | International Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues									1,326	1,447	1,444
Wholesale Electric [Member] | Commercial Power [Member]
Segment Reporting Information [Line Items]
Operating revenues									255	260	307
Retail Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues									571	506	470
Retail Gas [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									571	506	470
Wholesale Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues									91	99	105
Wholesale Gas [Member] | International Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues									91	99	105
Other Revenues [Member]
Segment Reporting Information [Line Items]
Operating revenues									814	847	717
Other Revenues [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									814	847	717
Operating Segments [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									22,271	20,910	16,080
Operating Segments [Member] | International Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues									1,417	1,546	1,549
Operating Segments [Member] | Commercial Power [Member]
Segment Reporting Information [Line Items]
Operating revenues									255	260	307
Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues									$ 23,943	$ 22,716	$ 17,936