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Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Revenue Recognition (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Subtotal	$ 459		$ 1,353
Alternative revenue programs, net of amortization	0	$ 0	(2)	$ 0
Other accrued (deferred) revenues, net	(11)		(38)
Total retail revenues	448		1,313
Wholesale revenues	67		119
Other operating revenue	10		35
Total Revenues	525	$ 515	1,467	$ 1,494
Gain on Derivative Instruments, Pretax	29		35
Residential [Member]
Disaggregation of Revenue [Line Items]
Subtotal	224		699
Commercial [Member]
Disaggregation of Revenue [Line Items]
Subtotal	171		484
Industrial [Member]
Disaggregation of Revenue [Line Items]
Subtotal	55		138
Direct Access customers [Member]
Disaggregation of Revenue [Line Items]
Subtotal	9		32
Revenue Subject to Refund [Member]
Disaggregation of Revenue [Line Items]
Net tax benefits due to the change in tax rate under the TCJA	$ 11		$ 36