Supplemental Guarantor Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidating Statements of Income
Revenues	$ 3,500	[1]	$ 4,059	[1]	$ 3,754	[1]	$ 3,990	[1]	$ 3,860	[1]	$ 4,674	[1]	$ 4,037	[1]	$ 3,576	[1]	$ 9,637	$ 10,400	$ 9,820
OPERATING EXPENSES:
Fuel																	2,471	2,317	1,432
Purchased power																	4,237	4,875	4,624
Other operating expenses	1,165		865		921		818		928		997		1,066		973		3,769	3,964	2,714
Pensions and OPEB mark-to-market adjustment	609		0		0		0		507		0		0		0		609	507	190
Provision for depreciation	287		273		285		279		283		284		279		220		1,124	1,066	750
General taxes																	985	978	776
Total operating expenses																	13,127	14,449	11,596
OPERATING INCOME (LOSS)	(34)		907		557		746		(230)		1,057		521		350		2,176	1,698	1,743
OTHER INCOME (EXPENSE):
Investment income																	77	114	117
Interest expense																	(1,001)	(1,008)	(845)
Capitalized interest																	72	70	165
Total other income (expense)																	(852)	(255)	(563)
INCOME (LOSS) BEFORE INCOME TAXES																	1,324	1,443	1,180
INCOME TAXES (BENEFITS)	(105)		309		127		222		24		325		114		111		553	574	462
NET INCOME	(148)		425		188		306		99		530		193		47		771	869	718
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(148)		425		188		306		99		530		193		47		771	869	718
Pension and OPEB prior service costs																	(115)	(90)	(220)
Amortized gain (loss) 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 taxes (benefits) on other comprehensive income (loss)																	(79)	(49)	(74)
Other comprehensive income (loss), net of tax																	(41)	1	(102)
COMPREHENSIVE INCOME																	730	870	616
FES Corp
Consolidating Statements of Income
Revenues																	5,804	5,387	5,665
OPERATING EXPENSES:
Fuel																	0	12	31
Other operating expenses																	434	574	314
Pensions and OPEB mark-to-market adjustment																	(2)	10	11
Provision for depreciation																	4	4	3
General taxes																	79	64	24
Impairment of long-lived assets																		0	0
Total operating expenses																	6,494	6,250	5,916
OPERATING INCOME (LOSS)																	(690)	(863)	(251)
OTHER INCOME (EXPENSE):
Investment income																	2	1	5
Miscellaneous income, including net income from equity investees																	1,284	924	453
Capitalized interest																	0	0	0
Total other income (expense)																	1,175	829	362
INCOME (LOSS) BEFORE INCOME TAXES																	485	(34)	111
INCOME TAXES (BENEFITS)																	298	25	(120)
NET INCOME																	187	(59)	231
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME																	187	(59)	231
Pension and OPEB prior service costs																	6	(12)	(30)
Amortized gain (loss) on derivative hedges																	(9)	12	23
Change in unrealized gain on available-for-sale securities																	(5)	16	8
Other comprehensive income (loss)																	(8)	16	1
Income taxes (benefits) on other comprehensive income (loss)																	(4)	2	4
Other comprehensive income (loss), net of tax																	(4)	14	(3)
COMPREHENSIVE INCOME																	183	(45)	228
FES Corp | Affiliates
OPERATING EXPENSES:
Purchased power																	4,098	4,208	3,948
OTHER INCOME (EXPENSE):
Interest expense																	(18)	(2)	0
FES Corp | Non-Affiliates
OPERATING EXPENSES:
Purchased power																	1,881	1,378	1,585
OTHER INCOME (EXPENSE):
Interest expense																	(93)	(94)	(96)
FGCO
Consolidating Statements of Income
Revenues																	2,124	2,666	2,435
OPERATING EXPENSES:
Fuel																	1,077	1,138	1,200
Other operating expenses																	338	427	357
Pensions and OPEB mark-to-market adjustment																	52	68	37
Provision for depreciation																	120	127	100
General taxes																	36	37	42
Impairment of long-lived assets																		294	388
Total operating expenses																	1,623	2,096	2,154
OPERATING INCOME (LOSS)																	501	570	281
OTHER INCOME (EXPENSE):
Investment income																	15	0	1
Miscellaneous income, including net income from equity investees																	20	24	1
Capitalized interest																	4	12	76
Total other income (expense)																	(78)	(76)	(39)
INCOME (LOSS) BEFORE INCOME TAXES																	423	494	242
INCOME TAXES (BENEFITS)																	(261)	(112)	74
NET INCOME																	684	606	168
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME																	684	606	168
Pension and OPEB prior service costs																	6	(13)	(29)
Amortized gain (loss) on derivative hedges																	0	0	0
Change in unrealized gain on available-for-sale securities																	0	0	0
Other comprehensive income (loss)																	6	(13)	(29)
Income taxes (benefits) on other comprehensive income (loss)																	1	(8)	(11)
Other comprehensive income (loss), net of tax																	5	(5)	(18)
COMPREHENSIVE INCOME																	689	601	150
FGCO | Affiliates
OPERATING EXPENSES:
Purchased power																	0	5	30
OTHER INCOME (EXPENSE):
Interest expense																	(7)	(3)	(8)
FGCO | Non-Affiliates
OPERATING EXPENSES:
Purchased power																	0	0	0
OTHER INCOME (EXPENSE):
Interest expense																	(110)	(109)	(109)
Nuclear Generation Corp
Consolidating Statements of Income
Revenues																	1,895	1,647	1,568
OPERATING EXPENSES:
Fuel																	210	194	172
Other operating expenses																	539	578	511
Pensions and OPEB mark-to-market adjustment																	116	93	59
Provision for depreciation																	157	150	148
General taxes																	21	23	28
Impairment of long-lived assets																		0	0
Total operating expenses																	1,301	1,290	1,150
OPERATING INCOME (LOSS)																	594	357	418
OTHER INCOME (EXPENSE):
Investment income																	67	56	53
Miscellaneous income, including net income from equity investees																	0	0	0
Capitalized interest																	33	23	16
Total other income (expense)																	46	13	2
INCOME (LOSS) BEFORE INCOME TAXES																	640	370	420
INCOME TAXES (BENEFITS)																	62	58	153
NET INCOME																	578	312	267
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME																	578	312	267
Pension and OPEB prior service costs																	0	0	0
Amortized gain (loss) on derivative hedges																	0	0	0
Change in unrealized gain on available-for-sale securities																	(5)	15	8
Other comprehensive income (loss)																	(5)	15	8
Income taxes (benefits) on other comprehensive income (loss)																	(2)	5	4
Other comprehensive income (loss), net of tax																	(3)	10	4
COMPREHENSIVE INCOME																	575	322	271
Nuclear Generation Corp | Affiliates
OPERATING EXPENSES:
Purchased power																	258	252	232
OTHER INCOME (EXPENSE):
Interest expense																	(4)	(2)	(2)
Nuclear Generation Corp | Non-Affiliates
OPERATING EXPENSES:
Purchased power																	0	0	0
OTHER INCOME (EXPENSE):
Interest expense																	(50)	(64)	(65)
Eliminations
Consolidating Statements of Income
Revenues																	(3,905)	(4,223)	(3,840)
OPERATING EXPENSES:
Fuel																	0	0	0
Other operating expenses																	49	51	48
Pensions and OPEB mark-to-market adjustment																	0	0	0
Provision for depreciation																	(5)	(6)	(5)
General taxes																	0	0	0
Impairment of long-lived assets																		0	0
Total operating expenses																	(3,861)	(4,178)	(3,796)
OPERATING INCOME (LOSS)																	(44)	(45)	(44)
OTHER INCOME (EXPENSE):
Investment income																	(18)	0	0
Miscellaneous income, including net income from equity investees																	(1,269)	(918)	(437)
Capitalized interest																	0	0	0
Total other income (expense)																	(1,206)	(855)	(373)
INCOME (LOSS) BEFORE INCOME TAXES																	(1,250)	(900)	(417)
INCOME TAXES (BENEFITS)																	12	18	18
NET INCOME																	(1,262)	(918)	(435)
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME																	(1,262)	(918)	(435)
Pension and OPEB prior service costs																	(6)	13	29
Amortized gain (loss) on derivative hedges																	0	0	0
Change in unrealized gain on available-for-sale securities																	5	(15)	(8)
Other comprehensive income (loss)																	(1)	(2)	21
Income taxes (benefits) on other comprehensive income (loss)																	1	3	7
Other comprehensive income (loss), net of tax																	(2)	(5)	14
COMPREHENSIVE INCOME																	(1,264)	(923)	(421)
Eliminations | Affiliates
OPERATING EXPENSES:
Purchased power																	(3,905)	(4,223)	(3,839)
OTHER INCOME (EXPENSE):
Interest expense																	19	(1)	0
Eliminations | Non-Affiliates
OPERATING EXPENSES:
Purchased power																	0	0	0
OTHER INCOME (EXPENSE):
Interest expense																	62	64	64
FES
Consolidating Statements of Income
Revenues	1,389		1,557		1,456		1,516		1,327		1,467		1,292		1,391		5,918	5,477	5,828
OPERATING EXPENSES:
Fuel																	1,287	1,344	1,403
Other operating expenses	329		343		393		295		347		390		413		480		1,360	1,630	1,230
Pensions and OPEB mark-to-market adjustment	166		0		0		0		171		0		0		0		166	171	107
Provision for depreciation	73		71		69		63		68		69		69		69		276	275	246
General taxes																	136	124	94
Impairment of long-lived assets																	0	294	388
Total operating expenses																	5,557	5,458	5,424
OPERATING INCOME (LOSS)	(51)		175		15		222		(340)		206		63		90		361	19	404
OTHER INCOME (EXPENSE):
Investment income																	66	57	59
Miscellaneous income, including net income from equity investees																	35	30	17
Capitalized interest																	37	35	92
Total other income (expense)																	(63)	(89)	(48)
INCOME (LOSS) BEFORE INCOME TAXES																	298	(70)	356
INCOME TAXES (BENEFITS)	(34)		68		1		76		(125)		78		10		26		111	(11)	125
NET INCOME	(35)		101		(1)		122		(253)		120		29		45		187	(59)	231
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(35)		101		(1)		122		(253)		120		29		45		187	(59)	231
Pension and OPEB prior service costs																	6	(12)	(30)
Amortized gain (loss) on derivative hedges																	(9)	12	23
Change in unrealized gain on available-for-sale securities																	(5)	16	8
Other comprehensive income (loss)																	(8)	16	1
Income taxes (benefits) on other comprehensive income (loss)																	(4)	2	4
Other comprehensive income (loss), net of tax																	(4)	14	(3)
COMPREHENSIVE INCOME																	183	(45)	228
FES | Affiliates
OPERATING EXPENSES:
Purchased power																	451	242	371
OTHER INCOME (EXPENSE):
Interest expense																	(10)	(8)	(10)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power																	1,881	1,378	1,585
OTHER INCOME (EXPENSE):
Interest expense																	$ (191)	$ (203)	$ (206)

[1] Reflects reclassification of revenues and purchased power costs from amounts previously reported to reflect the impact of netting transactions for FES and AE Supply on an hourly basis. This reclassification had no impact on net income or cash flows.