Taxes (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in unrecognized tax benefits
Beginning balance	$ 34	$ 34	$ 48
Current year increases	2	3	4
Prior years increases	69	7	5
Prior years decreases	(21)	(10)	(23)
Ending balance	84	34	34
FES
Changes in unrecognized tax benefits
Beginning balance	8	3	3
Current year increases	0	0	0
Prior years increases	0	5	0
Prior years decreases	(8)	0	0
Ending balance	$ 0	$ 8	$ 3