Supplemental Guarantor Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Consolidating Statements of Income
Revenues									$ 15,049	[1]	$ 14,892	[1]	$ 15,255	[1]
OPERATING EXPENSES:
Fuel									2,280		2,496		2,471
Purchased power									4,716		3,963		4,246
Other operating expenses	901	858	1,021	1,182	948	877	886	882	3,962		3,593		3,760
Pension and OPEB mark-to-market adjustment	835	0	0	0	(256)	0	0	0	835		(256)		609
Provision for depreciation	316	308	302	294	293	316	300	293	1,220		1,202		1,119
General taxes									962		978		984
Total operating expenses									13,987		13,310		13,121
OPERATING INCOME (LOSS)	(337)	716	292	391	387	508	42	645	1,062		1,582		2,134
OTHER INCOME (EXPENSE):
Loss on debt redemptions									(8)		(132)		0
Investment income									72		33		77
Interest expense									(1,073)		(1,016)		(1,001)
Capitalized financing costs									118		103		90
Total other expense									(891)		(1,012)		(834)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES									171		570		1,300
INCOME TAXES (BENEFITS)	(268)	152	26	48	66	77	(62)	114	(42)		195		545
INCOME FROM CONTINUING OPERATIONS	(306)	333	64	122	142	209	(168)	192	213		375		755
Discontinued operations (net of income taxes of $69, $9 and $8, respectively) (Note 19)	0	0	0	86	0	9	4	4	86		17		16
NET INCOME (LOSS)	(306)	333	64	208	142	218	(164)	196	299		392		771
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(306)	333	64	208	142	218	(164)	196	299		392		771
Pension and OPEB prior service costs									(76)		(160)		(115)
Amortized loss (gain) on derivative hedges									(2)		3		1
Change in unrealized gain on available-for-sale securities									26		(10)		(6)
Other comprehensive income (loss)									(52)		(167)		(120)
Income taxes (benefits) on other comprehensive income (loss)									(14)		(66)		(79)
Other comprehensive loss, net of tax									(38)		(101)		(41)
COMPREHENSIVE INCOME (LOSS)									261		291		730
Tax effect of discontinued operations									69		9		8
FES
Consolidating Statements of Income
Revenues									5,990		6,068		5,804
OPERATING EXPENSES:
Fuel									0		0		0
Other operating expenses									790		635		434
Pension and OPEB mark-to-market adjustment									19		(8)		(2)
Provision for depreciation									10		6		4
General taxes									72		80		79
Total operating expenses									7,578		7,187		6,494
OPERATING INCOME (LOSS)									(1,588)		(1,119)		(690)
OTHER INCOME (EXPENSE):
Loss on debt redemptions									(3)		(103)
Investment income									7		5		2
Miscellaneous income, including net income from equity investees									786		846		1,284
Capitalized financing costs									0		1		0
Total other expense									725		673		1,175
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES									(863)		(446)		485
INCOME TAXES (BENEFITS)									(619)		(506)		298
INCOME FROM CONTINUING OPERATIONS									(244)		60		187
Discontinued operations (net of income taxes of $69, $9 and $8, respectively) (Note 19)									0		0		0
NET INCOME (LOSS)									(244)		60		187
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME									(244)		60		187
Pension and OPEB prior service costs									(6)		(15)		6
Amortized loss (gain) on derivative hedges									(10)		(6)		(9)
Change in unrealized gain on available-for-sale securities									21		(8)		(5)
Other comprehensive income (loss)									5		(29)		(8)
Income taxes (benefits) on other comprehensive income (loss)									2		(11)		(4)
Other comprehensive loss, net of tax									3		(18)		(4)
COMPREHENSIVE INCOME (LOSS)									(241)		42		183
FES | Affiliates
OPERATING EXPENSES:
Purchased power									3,920		4,148		4,098
OTHER INCOME (EXPENSE):
Interest expense									(12)		(13)		(18)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power									2,767		2,326		1,881
OTHER INCOME (EXPENSE):
Interest expense									(53)		(63)		(93)
FGCO
Consolidating Statements of Income
Revenues									1,902		2,399		2,100
OPERATING EXPENSES:
Fuel									1,055		1,056		1,077
Other operating expenses									269		275		334
Pension and OPEB mark-to-market adjustment									90		(37)		52
Provision for depreciation									119		127		116
General taxes									31		34		36
Total operating expenses									1,568		1,462		1,621
OPERATING INCOME (LOSS)									334		937		479
OTHER INCOME (EXPENSE):
Loss on debt redemptions									(1)		0
Investment income									8		1		15
Miscellaneous income, including net income from equity investees									4		24		20
Capitalized financing costs									4		2		4
Total other expense									(92)		(82)		(78)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES									242		855		401
INCOME TAXES (BENEFITS)									87		365		(269)
INCOME FROM CONTINUING OPERATIONS									155		490		670
Discontinued operations (net of income taxes of $69, $9 and $8, respectively) (Note 19)									116		14		14
NET INCOME (LOSS)									271		504		684
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME									271		504		684
Pension and OPEB prior service costs									(5)		(13)		6
Amortized loss (gain) on derivative hedges									0		0		0
Change in unrealized gain on available-for-sale securities									0		0		0
Other comprehensive income (loss)									(5)		(13)		6
Income taxes (benefits) on other comprehensive income (loss)									(2)		(5)		1
Other comprehensive loss, net of tax									(3)		(8)		5
COMPREHENSIVE INCOME (LOSS)									268		496		689
FGCO | Affiliates
OPERATING EXPENSES:
Purchased power									0		0		0
OTHER INCOME (EXPENSE):
Interest expense									(6)		(5)		(7)
FGCO | Non-Affiliates
OPERATING EXPENSES:
Purchased power									4		7		6
OTHER INCOME (EXPENSE):
Interest expense									(101)		(104)		(110)
Nuclear Generation Corp
Consolidating Statements of Income
Revenues									2,172		1,634		1,895
OPERATING EXPENSES:
Fuel									198		206		210
Other operating expenses									527		529		539
Pension and OPEB mark-to-market adjustment									188		(36)		116
Provision for depreciation									193		178		157
General taxes									25		24		21
Total operating expenses									1,402		1,167		1,301
OPERATING INCOME (LOSS)									770		467		594
OTHER INCOME (EXPENSE):
Loss on debt redemptions									(2)		0
Investment income									61		25		67
Miscellaneous income, including net income from equity investees									0		0		0
Capitalized financing costs									30		36		33
Total other expense									33		1		46
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES									803		468		640
INCOME TAXES (BENEFITS)									298		135		62
INCOME FROM CONTINUING OPERATIONS									505		333		578
Discontinued operations (net of income taxes of $69, $9 and $8, respectively) (Note 19)									0		0		0
NET INCOME (LOSS)									505		333		578
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME									505		333		578
Pension and OPEB prior service costs									0		0		0
Amortized loss (gain) on derivative hedges									0		0		0
Change in unrealized gain on available-for-sale securities									21		(8)		(5)
Other comprehensive income (loss)									21		(8)		(5)
Income taxes (benefits) on other comprehensive income (loss)									8		(3)		(2)
Other comprehensive loss, net of tax									13		(5)		(3)
COMPREHENSIVE INCOME (LOSS)									518		328		575
Nuclear Generation Corp | Affiliates
OPERATING EXPENSES:
Purchased power									271		266		258
OTHER INCOME (EXPENSE):
Interest expense									(4)		(6)		(4)
Nuclear Generation Corp | Non-Affiliates
OPERATING EXPENSES:
Purchased power									0		0		0
OTHER INCOME (EXPENSE):
Interest expense									(52)		(54)		(50)
Eliminations
Consolidating Statements of Income
Revenues									(3,920)		(3,928)		(3,905)
OPERATING EXPENSES:
Fuel									0		0		0
Other operating expenses									49		48		49
Pension and OPEB mark-to-market adjustment									0		0		0
Provision for depreciation									(3)		(5)		(5)
General taxes									0		0		0
Total operating expenses									(3,874)		(3,885)		(3,861)
OPERATING INCOME (LOSS)									(46)		(43)		(44)
OTHER INCOME (EXPENSE):
Loss on debt redemptions									0		0
Investment income									(15)		(15)		(18)
Miscellaneous income, including net income from equity investees									(784)		(842)		(1,269)
Capitalized financing costs									0		0		0
Total other expense									(724)		(782)		(1,206)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES									(770)		(825)		(1,250)
INCOME TAXES (BENEFITS)									6		12		12
INCOME FROM CONTINUING OPERATIONS									(776)		(837)		(1,262)
Discontinued operations (net of income taxes of $69, $9 and $8, respectively) (Note 19)									0		0		0
NET INCOME (LOSS)									(776)		(837)		(1,262)
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME									(776)		(837)		(1,262)
Pension and OPEB prior service costs									5		13		(6)
Amortized loss (gain) on derivative hedges									0		0		0
Change in unrealized gain on available-for-sale securities									(21)		8		5
Other comprehensive income (loss)									(16)		21		(1)
Income taxes (benefits) on other comprehensive income (loss)									(6)		8		1
Other comprehensive loss, net of tax									(10)		13		(2)
COMPREHENSIVE INCOME (LOSS)									(786)		(824)		(1,264)
Eliminations | Affiliates
OPERATING EXPENSES:
Purchased power									(3,920)		(3,928)		(3,905)
OTHER INCOME (EXPENSE):
Interest expense									15		14		19
Eliminations | Non-Affiliates
OPERATING EXPENSES:
Purchased power									0		0		0
OTHER INCOME (EXPENSE):
Interest expense									60		61		62
FES
Consolidating Statements of Income
Revenues									6,144	[2]	6,173	[2]	5,894	[2]
OPERATING EXPENSES:
Fuel									1,253		1,262		1,287
Other operating expenses	359	356	468	452	382	339	387	379	1,635		1,487		1,356
Pension and OPEB mark-to-market adjustment	297	0	0	0	(81)	0	0	0	297		(81)		166
Provision for depreciation	83	83	79	74	75	80	76	75	319		306		272
General taxes									128		138		136
Total operating expenses									6,674		5,931		5,555
OPERATING INCOME (LOSS)	(321)	90	(151)	(148)	121	65	(39)	95	(530)		242		339
OTHER INCOME (EXPENSE):
Loss on debt redemptions									(6)		(103)		0
Investment income									61		16		66
Miscellaneous income, including net income from equity investees									6		28		35
Capitalized financing costs									34		39		37
Total other expense									(58)		(190)		(63)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES									(588)		52		276
INCOME TAXES (BENEFITS)	(133)	28	(67)	(56)	25	23	(42)	0	(228)		6		103
INCOME FROM CONTINUING OPERATIONS	(214)	44	(87)	(103)	89	33	(75)	(1)	(360)		46		173
Discontinued operations (net of income taxes of $69, $9 and $8, respectively) (Note 19)	0	0	0	116	0	7	4	3	116		14		14
NET INCOME (LOSS)	(214)	44	(87)	13	89	40	(71)	2	(244)		60		187
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(214)	44	(87)	13	89	40	(71)	2	(244)		60		187
Pension and OPEB prior service costs									(6)		(15)		6
Amortized loss (gain) on derivative hedges									(10)		(6)		(9)
Change in unrealized gain on available-for-sale securities									21		(8)		(5)
Other comprehensive income (loss)									5		(29)		(8)
Income taxes (benefits) on other comprehensive income (loss)									2		(11)		(4)
Other comprehensive loss, net of tax									3		(18)		(4)
COMPREHENSIVE INCOME (LOSS)									(241)		42		183
Tax effect of discontinued operations									70		8		8
FES | Affiliates
OPERATING EXPENSES:
Purchased power									271		486		451
OTHER INCOME (EXPENSE):
Interest expense									(7)		(10)		(10)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power									2,771		2,333		1,887
OTHER INCOME (EXPENSE):
Interest expense									$ (146)		$ (160)		$ (191)

[1] Includes excise tax collections of $420 million, $458 million and $484 million in 2014, 2013 and 2012, respectively.

[2] Includes excise tax collections of $69 million, $78 million and $77 million in 2014, 2013 and 2012, respectively.