Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Subtotal	$ 448	$ 459	$ 1,370	$ 1,353
Alternative revenue programs, net of amortization	4	0	5	(2)
Other accrued (deferred) revenues, net	4	(11)	17	(38)
Total retail revenues	456	448	1,392	1,313
Wholesale revenues	72	67	125	119
Other operating revenue	14	10	58	35
Total Revenues	542	525	1,575	1,467
Gain on Derivative Instruments, Pretax	25	29	38	35
Residential [Member]
Disaggregation of Revenue [Line Items]
Subtotal	218	224	713	699
Commercial [Member]
Disaggregation of Revenue [Line Items]
Subtotal	167	171	479	484
Industrial [Member]
Disaggregation of Revenue [Line Items]
Subtotal	50	55	144	138
Direct Access customers [Member]
Disaggregation of Revenue [Line Items]
Subtotal	13	9	34	32
Revenue Subject to Refund [Member]
Disaggregation of Revenue [Line Items]
Net tax benefits due to the change in tax rate under the TCJA	$ 6	$ 11	$ 17	$ 36