Derivative Instruments (Details 2) MWh in Millions, MMBTU in Millions	Dec. 31, 2016 MWh MMBTU
Power Contracts
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	18
Sales (in MWH or mmBTUs)	47
Net (in MWH or mmBTUs)	(29)
FTRs
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	28
Sales (in MWH or mmBTUs)	0
Net (in MWH or mmBTUs)	28
NUGs
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	3
Sales (in MWH or mmBTUs)	0
Net (in MWH or mmBTUs)	3
Natural Gas
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs) | MMBTU	29
Sales (in MWH or mmBTUs) | MMBTU	29
Net (in MWH or mmBTUs) | MMBTU	0
FES | Power Contracts
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	18
Sales (in MWH or mmBTUs)	47
Net (in MWH or mmBTUs)	(29)
FES | FTRs
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs)	22
Sales (in MWH or mmBTUs)	0
Net (in MWH or mmBTUs)	22
FES | Natural Gas
Volume of First Energy's outstanding derivative transactions
Purchases (in MWH or mmBTUs) | MMBTU	29
Sales (in MWH or mmBTUs) | MMBTU	29
Net (in MWH or mmBTUs) | MMBTU	0