Supplemental Guarantor Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Discontinued Operation, Tax Effect of Discontinued Operation	$ 69	$ 2
Consolidating Statements of Income
Revenues	2,739	2,388
OPERATING EXPENSES:
Fuel	617	630
Purchased power	1,455	946
Other operating expenses	1,182	882
Provision for depreciation	294	293
General taxes	271	265
Total operating expenses	3,791	3,075
OPERATING INCOME (LOSS)	398	648
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(7)	(117)
Investment income	22	18
Interest expense	(265)	(258)
Capitalized interest	22	15
Total other income (expense)	(228)	(342)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	170	306
INCOME TAXES (BENEFITS)	48	114
INCOME FROM CONTINUING OPERATIONS	122	192
Discontinued operations (Note 13)	86	4
NET INCOME (LOSS)	208	196
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	208	196
Pension and OPEB prior service costs	(42)	(46)
Amortized loss (gain) on derivative hedges	0	1
Change in unrealized gain on available-for-sale securities	21	5
Other comprehensive income (loss)	(21)	(40)
Income taxes (benefits) on other comprehensive income (loss)	(8)	(16)
Net other comprehensive income (loss)	(13)	(24)
COMPREHENSIVE INCOME (LOSS)	195	172
FES
Consolidating Statements of Income
Revenues	1,797	1,496
OPERATING EXPENSES:
Fuel	0	0
Other operating expenses	228	162
Provision for depreciation	2	1
General taxes	21	20
Total operating expenses	1,921	1,701
OPERATING INCOME (LOSS)	(124)	(205)
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(3)	(71)
Investment income	1	1
Miscellaneous income, including net income from equity investees	103	192
Capitalized interest	0	0
Total other income (expense)	84	95
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(40)	(110)
INCOME TAXES (BENEFITS)	(52)	(112)
INCOME FROM CONTINUING OPERATIONS	12	2
Discontinued operations (Note 13)	0	0
NET INCOME (LOSS)	12	2
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	12	2
Pension and OPEB prior service costs	(5)	(6)
Amortized loss (gain) on derivative hedges	(2)	(1)
Change in unrealized gain on available-for-sale securities	19	5
Other comprehensive income (loss)	12	(2)
Income taxes (benefits) on other comprehensive income (loss)	4	(1)
Net other comprehensive income (loss)	8	(1)
COMPREHENSIVE INCOME (LOSS)	20	1
FES | Affiliates
OPERATING EXPENSES:
Purchased power	645	1,013
OTHER INCOME (EXPENSE):
Interest expense	(3)	(2)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power	1,025	505
OTHER INCOME (EXPENSE):
Interest expense	(14)	(25)
FGCO
Condensed Financial Statements, Captions [Line Items]
Discontinued Operation, Tax Effect of Discontinued Operation	70	2
Consolidating Statements of Income
Revenues	315	531
OPERATING EXPENSES:
Fuel	272	247
Other operating expenses	62	74
Provision for depreciation	29	31
General taxes	11	11
Total operating expenses	378	364
OPERATING INCOME (LOSS)	(63)	167
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(1)	0
Investment income	1	0
Miscellaneous income, including net income from equity investees	0	1
Capitalized interest	1	0
Total other income (expense)	(24)	(28)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(87)	139
INCOME TAXES (BENEFITS)	(31)	51
INCOME FROM CONTINUING OPERATIONS	(56)	88
Discontinued operations (Note 13)	116	3
NET INCOME (LOSS)	60	91
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	60	91
Pension and OPEB prior service costs	(4)	(5)
Amortized loss (gain) on derivative hedges	0	0
Change in unrealized gain on available-for-sale securities	0	0
Other comprehensive income (loss)	(4)	(5)
Income taxes (benefits) on other comprehensive income (loss)	(2)	(2)
Net other comprehensive income (loss)	(2)	(3)
COMPREHENSIVE INCOME (LOSS)	58	88
FGCO | Affiliates
OPERATING EXPENSES:
Purchased power	0	0
OTHER INCOME (EXPENSE):
Interest expense	(1)	(1)
FGCO | Non-Affiliates
OPERATING EXPENSES:
Purchased power	4	1
OTHER INCOME (EXPENSE):
Interest expense	(24)	(28)
Nuclear Generation Corp
Consolidating Statements of Income
Revenues	362	440
OPERATING EXPENSES:
Fuel	47	53
Other operating expenses	150	131
Provision for depreciation	43	44
General taxes	7	6
Total operating expenses	311	296
OPERATING INCOME (LOSS)	51	144
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(1)	0
Investment income	21	18
Miscellaneous income, including net income from equity investees	0	0
Capitalized interest	11	9
Total other income (expense)	17	11
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	68	155
INCOME TAXES (BENEFITS)	26	58
INCOME FROM CONTINUING OPERATIONS	42	97
Discontinued operations (Note 13)	0	0
NET INCOME (LOSS)	42	97
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	42	97
Pension and OPEB prior service costs	0	0
Amortized loss (gain) on derivative hedges	0	0
Change in unrealized gain on available-for-sale securities	19	5
Other comprehensive income (loss)	19	5
Income taxes (benefits) on other comprehensive income (loss)	7	2
Net other comprehensive income (loss)	12	3
COMPREHENSIVE INCOME (LOSS)	54	100
Nuclear Generation Corp | Affiliates
OPERATING EXPENSES:
Purchased power	64	62
OTHER INCOME (EXPENSE):
Interest expense	(1)	(1)
Nuclear Generation Corp | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0
OTHER INCOME (EXPENSE):
Interest expense	(13)	(15)
Eliminations
Consolidating Statements of Income
Revenues	(645)	(943)
OPERATING EXPENSES:
Fuel	0	0
Other operating expenses	12	12
Provision for depreciation	0	(1)
General taxes	0	0
Total operating expenses	(633)	(932)
OPERATING INCOME (LOSS)	(12)	(11)
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0	0
Investment income	(3)	(2)
Miscellaneous income, including net income from equity investees	(103)	(191)
Capitalized interest	0	0
Total other income (expense)	(88)	(174)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(100)	(185)
INCOME TAXES (BENEFITS)	1	3
INCOME FROM CONTINUING OPERATIONS	(101)	(188)
Discontinued operations (Note 13)	0	0
NET INCOME (LOSS)	(101)	(188)
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(101)	(188)
Pension and OPEB prior service costs	4	5
Amortized loss (gain) on derivative hedges	0	0
Change in unrealized gain on available-for-sale securities	(19)	(5)
Other comprehensive income (loss)	(15)	0
Income taxes (benefits) on other comprehensive income (loss)	(5)	0
Net other comprehensive income (loss)	(10)	0
COMPREHENSIVE INCOME (LOSS)	(111)	(188)
Eliminations | Affiliates
OPERATING EXPENSES:
Purchased power	(645)	(943)
OTHER INCOME (EXPENSE):
Interest expense	3	3
Eliminations | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0
OTHER INCOME (EXPENSE):
Interest expense	15	16
FES
Condensed Financial Statements, Captions [Line Items]
Discontinued Operation, Tax Effect of Discontinued Operation	70	2
Consolidating Statements of Income
Revenues	1,829	1,524
OPERATING EXPENSES:
Fuel	319	300
Other operating expenses	452	379
Provision for depreciation	74	75
General taxes	39	37
Total operating expenses	1,977	1,429
OPERATING INCOME (LOSS)	(148)	95
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(5)	(71)
Investment income	20	17
Miscellaneous income, including net income from equity investees	0	2
Capitalized interest	12	9
Total other income (expense)	(11)	(96)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(159)	(1)
INCOME TAXES (BENEFITS)	(56)	0
INCOME FROM CONTINUING OPERATIONS	(103)	(1)
Discontinued operations (Note 13)	116	3
NET INCOME (LOSS)	13	2
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	13	2
Pension and OPEB prior service costs	(5)	(6)
Amortized loss (gain) on derivative hedges	(2)	(1)
Change in unrealized gain on available-for-sale securities	19	5
Other comprehensive income (loss)	12	(2)
Income taxes (benefits) on other comprehensive income (loss)	4	(1)
Net other comprehensive income (loss)	8	(1)
COMPREHENSIVE INCOME (LOSS)	21	1
FES | Affiliates
OPERATING EXPENSES:
Purchased power	64	132
OTHER INCOME (EXPENSE):
Interest expense	(2)	(1)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power	1,029	506
OTHER INCOME (EXPENSE):
Interest expense	$ (36)	$ (52)