Derivative Instruments (Details 2) MWh in Millions	Dec. 31, 2017 MWh
Power Contracts
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	2
Sales (in MWH or mmBTUs)	11
Net (in MWH or mmBTUs)	(9)
FTRs
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	9
Sales (in MWH or mmBTUs)	0
Net (in MWH or mmBTUs)	9
NUGs
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	2
Sales (in MWH or mmBTUs)	0
Net (in MWH or mmBTUs)	2
FES | Power Contracts
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	2
Sales (in MWH or mmBTUs)	11
Net (in MWH or mmBTUs)	(9)
FES | FTRs
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	5
Sales (in MWH or mmBTUs)	0
Net (in MWH or mmBTUs)	5