Consolidated Balance Sheets (FirstEnergy Corp.) (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Common stockholders’ equity-
Common stock, par value (in dollars per share)	$ 0.1	$ 0.1
Common stock, shares authorized	700,000,000	490,000,000
Common stock, shares outstanding	445,334,111	442,344,218
Customer [Member]
Receivables-
Allowance for uncollectible accounts (in dollars)	$ 51	$ 53
Other [Member]
Receivables-
Allowance for uncollectible accounts (in dollars)	$ 1	$ 1