Goodwill And Other Intangibles (Schedule of Intangibles) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Purchases of Intangible Assets	$ 146	$ 117	$ 99
Intangible Assets	143	114
Power [Member]
Goodwill [Line Items]
Retirement of Intangibles	(116)	(100)
Purchases of Intangible Assets	146	117	99
Sales and Transfers of Intangible Assets	(1)	(1)
Intangible Assets	143	114	98
Renewable Energy Credits [Member] | Power [Member]
Goodwill [Line Items]
Retirement of Intangibles	(90)	(93)
Purchases of Intangible Assets	110	90
Sales and Transfers of Intangible Assets	(1)	(1)
Intangible Assets	59	40	44
Emissions Allowances [Member] | Power [Member]
Goodwill [Line Items]
Retirement of Intangibles	(26)	(7)
Purchases of Intangible Assets	36	27
Sales and Transfers of Intangible Assets	0	0
Intangible Assets	$ 84	$ 74	$ 54