Organization and Basis of Presentation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Regulatory assets on the Balance Sheets
Regulatory Assets	$ 99	$ 91
Regulatory Liability	(2,360)	(2,498)
Net Regulatory Liabilities included on the Consolidated Balance Sheets	(2,261)	(2,407)
Change	146
Regulatory transition costs
Regulatory assets on the Balance Sheets
Regulatory Assets	(8)	49
Change	(57)
Customer payables for future income taxes
Regulatory assets on the Balance Sheets
Regulatory Liability	(2,605)	(2,725)
Change	120
Nuclear decommissioning and spent fuel disposal costs
Regulatory assets on the Balance Sheets
Regulatory Liability	(197)	(148)
Change	(49)
Asset removal costs
Regulatory assets on the Balance Sheets
Regulatory Liability	(756)	(787)
Change	31
Deferred transmission costs
Regulatory assets on the Balance Sheets
Regulatory Assets	298	170
Change	128
Deferred generation costs
Regulatory assets on the Balance Sheets
Regulatory Assets	214	202
Change	12
Deferred distribution costs
Regulatory assets on the Balance Sheets
Regulatory Assets	155	208
Change	(53)
Contract valuations
Regulatory assets on the Balance Sheets
Regulatory Assets	51	72
Change	(21)
Storm-related costs
Regulatory assets on the Balance Sheets
Regulatory Assets	551	500
Change	51
Other
Regulatory assets on the Balance Sheets
Regulatory Assets	36	$ 52
Change	$ (16)