Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Currently payable (receivable)-
Federal									$ (1)	$ 1	$ (132)
State									9	30	(72)
Currently payable (receivable) Total									8	31	(204)
Deferred, net-
Federal									(3,114)	277	214
State									59	15	(42)
Deferred Tax Total									(3,055)	292	172
Investment tax credit amortization									(8)	(8)	(10)
Total provision for income taxes (benefits)	$ (3,389)	$ 251	$ (130)	$ 213	$ (170)	$ 226	$ 115	$ 144	(3,055)	315	(42)
Internal Revenue Service (IRS)
Deferred, net-
Current tax effect of discontinued operation											106
Deferred tax effect of discontinued operation											44
State and Local
Deferred, net-
Current tax effect of discontinued operation											12
Deferred tax effect of discontinued operation											5
FES
Currently payable (receivable)-
Federal									(67)	(56)	(222)
State									(1)	2	(13)
Currently payable (receivable) Total									(68)	(54)	(235)
Deferred, net-
Federal									(2,861)	103	25
State									(57)	18	(14)
Deferred Tax Total									(2,918)	121	11
Investment tax credit amortization									(2)	(2)	(4)
Total provision for income taxes (benefits)	$ (2,983)	$ 56	$ (143)	$ 82	$ 1	$ 70	$ (4)	$ (2)	$ (2,988)	$ 65	$ (228)