Consolidated Statements of Comprehensive Income (FirstEnergy Corp.) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement of Other Comprehensive Income [Abstract]
NET INCOME	$ 771	$ 869	$ 718
OTHER COMPREHENSIVE INCOME (LOSS):
Pension and OPEB prior service costs	(115)	(90)	(220)
Amortized losses on derivative hedges	1	23	36
Change in unrealized gain on available-for-sale securities	(6)	19	8
Other comprehensive income (loss)	(120)	(48)	(176)
Income tax benefits on other comprehensive loss	(79)	(49)	(74)
Other comprehensive income (loss), net of tax	(41)	1	(102)
COMPREHENSIVE INCOME	730	870	616
Comprehensive income (loss) attributable to noncontrolling interest	1	(16)	(24)
COMPREHENSIVE INCOME AVAILABLE TO FIRSTENERGY CORP.	$ 729	$ 886	$ 640