Taxes (Details 5) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
General Taxes
KWH excise	$ 188	$ 196	$ 193
State gross receipts	204	212	224
Real and personal property	486	472	410
Social security and unemployment	131	127	119
Other	34	35	32
Total general taxes	1,043	1,042	978
FES
General Taxes
State gross receipts	20	28	44
Real and personal property	27	42	36
Social security and unemployment	11	15	16
Other	0	3	2
Total general taxes	$ 58	$ 88	$ 98