Consolidated Statements of Common Stockholders' Equity (FirstEnergy Solutions Corp.) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unrealized gain (loss) on derivative hedges taxes	$ 3	$ 1	$ (1)
Unrealized gain (loss) on investment taxes	21	4	10
Taxes on pension and other postretirement taxes	(23)	(44)	(23)
FES
Unrealized gain (loss) on derivative hedges taxes	0	(1)	(4)
Unrealized gain (loss) on investment taxes	20	(4)	8
Taxes on pension and other postretirement taxes	$ (5)	$ (2)	$ (2)