Taxes (Details 5) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
General Taxes
KWH excise	$ 191	$ 198	$ 188
State gross receipts	185	192	184
Real and personal property	504	478	452
Social security and unemployment	100	103	96
Other	28	22	20
Total general taxes	$ 1,008	$ 993	$ 940