Consolidated Statements of Income (FirstEnergy Corp.) - USD ($) shares in Millions, $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Investment Income, Net										$ (22)	$ 72	$ 33
REVENUES:
Electric utilities		$ 3,541	$ 4,123	$ 3,465	$ 3,897	$ 3,483	$ 3,888	$ 3,496	$ 4,182	10,636	9,871	9,451
Unregulated businesses										4,390	5,178	5,441
Total revenues	[1]									15,026	15,049	14,892
OPERATING EXPENSES:
Fuel										1,855	2,280	2,496
Purchased power										4,318	4,716	3,963
Other operating expenses		952	850	916	1,057	901	858	1,021	1,182	3,749	3,962	3,593
Pension and OPEB mark-to-market adjustment		242	0	0	0	835	0	0	0	242	835	(256)
Provision for depreciation		313	328	322	319	316	308	302	294	1,282	1,220	1,202
Amortization of regulatory assets, net										268	12	539
General taxes										978	962	978
Impairment of long-lived assets										42	0	795
Total operating expenses										12,734	13,987	13,310
OPERATING INCOME (LOSS)		236	908	554	594	(337)	716	292	391	2,292	1,062	1,582
OTHER INCOME (EXPENSE):
Loss on debt redemptions										0	(8)	(132)
Impairment of equity method investment										(362)	0	0
Interest expense										(1,132)	(1,073)	(1,016)
Capitalized financing costs										117	118	103
Total other expense										(1,399)	(891)	(1,012)
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES (BENEFITS)										893	171	570
INCOME TAXES (BENEFITS)		(170)	226	115	144	(268)	152	26	48	315	(42)	195
INCOME (LOSS) FROM CONTINUING OPERATIONS		(226)	395	187	222	(306)	333	64	122	578	213	375
Discontinued operations (net of income taxes of $0, $69 and $9, respectively) (Note 19)		0	0	0	0	0	0	0	86	0	86	17
NET INCOME (LOSS)		$ (226)	$ 395	$ 187	$ 222	$ (306)	$ 333	$ 64	$ 208	578	299	392
EARNINGS AVAILABLE TO FIRSTENERGY CORP.										$ 578	$ 299	$ 392
EARNINGS PER SHARE OF COMMON STOCK:
Basic - Continuing Operations, in dollars per share		$ (0.53)	$ 0.94	$ 0.44	$ 0.53	$ (0.73)	$ 0.79	$ 0.16	$ 0.29	$ 1.37	$ 0.51	$ 0.90
Basic - Discontinued Operations, in dollars per share		0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.21	0.00	0.20	0.04
Basic - Earnings Available to FirstEnergy Corp., in dollars per share		(0.53)	0.94	0.44	0.53	(0.73)	0.79	0.16	0.50	1.37	0.71	0.94
Diluted - Continuing Operations, in dollars per share		(0.53)	0.93	0.44	0.53	(0.73)	0.79	0.15	0.29	1.37	0.51	0.90
Diluted - Discontinued Operations, in dollars per share		0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.20	0.00	0.20	0.04
Diluted - Earnings Available to FirstEnergy Corp., in dollars per share		$ (0.53)	$ 0.93	$ 0.44	$ 0.53	$ (0.73)	$ 0.79	$ 0.15	$ 0.49	$ 1.37	$ 0.71	$ 0.94
WEIGHTED AVERAGE NUMBER OF SHARES OUTSTANDING:
Basic, in shares										422	420	418
Diluted, in shares										424	421	419
DIVIDENDS DECLARED PER SHARE OF COMMON STOCK, in dollars per share										$ 1.44	$ 1.44	$ 1.65

[1] Includes excise tax collections of $416 million, $420 million and $458 million in 2015, 2014 and 2013, respectively.