Taxes (Details 5) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Changes in unrecognized tax benefits
Beginning balance	$ 34	$ 48	$ 43
Current year increases	3	4
Prior years increases	7	5	10
Prior years decreases	(10)	(23)	(5)
Ending balance	34	34	48
FES
Changes in unrecognized tax benefits
Beginning balance	3	3	3
Current year increases	0	0
Prior years increases	5	0	0
Prior years decreases	0	0	0
Ending balance	$ 8	$ 3	$ 3