Supplemental Guarantor Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Consolidating Statements of Income
Revenues	$ 2,388	$ 2,540
OPERATING EXPENSES:
Fuel	630	541
Purchased power	943	1,259
Other operating expenses	884	818
Provision for depreciation	294	279
General taxes	265	272
Total operating expenses	3,075	3,244
OPERATING INCOME (LOSS)	654	746
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(119)	0
Investment income	18	11
Interest expense	(256)	(246)
Capitalized interest	15	17
Total other income (expense)	(342)	(218)
Total before taxes	312	528
INCOME TAXES (BENEFITS)	116	222
Net of tax	196	306
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	196	306
Pension and OPEB prior service costs	(46)	(53)
Amortized gain (loss) on derivative hedges	1	(2)
Change in unrealized gain on available-for-sale securities	5	10
Other comprehensive income (loss)	(40)	(45)
Income taxes (benefits) on other comprehensive income (loss)	(16)	(24)
Net other comprehensive income (loss)	(24)	(21)
COMPREHENSIVE INCOME	172	285
FES
Consolidating Statements of Income
Revenues	1,496	1,490
OPERATING EXPENSES:
Fuel	0	0
Other operating expenses	162	76
Provision for depreciation	1	1
General taxes	20	20
Total operating expenses	1,701	1,549
OPERATING INCOME (LOSS)	(205)	(59)
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(73)
Investment income	1	1
Miscellaneous income, including net income from equity investees	192	258
Capitalized interest	0	0
Total other income (expense)	95	232
Total before taxes	(110)	173
INCOME TAXES (BENEFITS)	(112)	51
Net of tax	2	122
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	2	122
Pension and OPEB prior service costs	(6)	(5)
Amortized gain (loss) on derivative hedges	(1)	(5)
Change in unrealized gain on available-for-sale securities	5	10
Other comprehensive income (loss)	(2)	0
Income taxes (benefits) on other comprehensive income (loss)	(1)	2
Net other comprehensive income (loss)	(1)	(2)
COMPREHENSIVE INCOME	1	120
FES | Affiliates
OPERATING EXPENSES:
Purchased power	1,013	965
OTHER INCOME (EXPENSE):
Interest expense	(2)	(4)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power	505	487
OTHER INCOME (EXPENSE):
Interest expense	(23)	(23)
FGCO
Consolidating Statements of Income
Revenues	537	542
OPERATING EXPENSES:
Fuel	247	240
Other operating expenses	75	92
Provision for depreciation	32	30
General taxes	11	10
Total operating expenses	365	372
OPERATING INCOME (LOSS)	172	170
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0
Investment income	0	4
Miscellaneous income, including net income from equity investees	1	0
Capitalized interest	0	1
Total other income (expense)	(28)	(22)
Total before taxes	144	148
INCOME TAXES (BENEFITS)	53	(1)
Net of tax	91	149
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	91	149
Pension and OPEB prior service costs	(5)	(4)
Amortized gain (loss) on derivative hedges	0	0
Change in unrealized gain on available-for-sale securities	0	0
Other comprehensive income (loss)	(5)	(4)
Income taxes (benefits) on other comprehensive income (loss)	(2)	(2)
Net other comprehensive income (loss)	(3)	(2)
COMPREHENSIVE INCOME	88	147
FGCO | Affiliates
OPERATING EXPENSES:
Purchased power	0	0
OTHER INCOME (EXPENSE):
Interest expense	(1)	(1)
FGCO | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0
OTHER INCOME (EXPENSE):
Interest expense	(28)	(26)
Nuclear Generation Corp
Consolidating Statements of Income
Revenues	440	394
OPERATING EXPENSES:
Fuel	53	55
Other operating expenses	131	116
Provision for depreciation	44	34
General taxes	6	7
Total operating expenses	296	274
OPERATING INCOME (LOSS)	144	120
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0
Investment income	18	5
Miscellaneous income, including net income from equity investees	0	0
Capitalized interest	9	8
Total other income (expense)	11	5
Total before taxes	155	125
INCOME TAXES (BENEFITS)	58	23
Net of tax	97	102
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	97	102
Pension and OPEB prior service costs	0	0
Amortized gain (loss) on derivative hedges	0	0
Change in unrealized gain on available-for-sale securities	5	10
Other comprehensive income (loss)	5	10
Income taxes (benefits) on other comprehensive income (loss)	2	4
Net other comprehensive income (loss)	3	6
COMPREHENSIVE INCOME	100	108
Nuclear Generation Corp | Affiliates
OPERATING EXPENSES:
Purchased power	62	62
OTHER INCOME (EXPENSE):
Interest expense	(1)	(1)
Nuclear Generation Corp | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0
OTHER INCOME (EXPENSE):
Interest expense	(15)	(7)
Eliminations
Consolidating Statements of Income
Revenues	(943)	(910)
OPERATING EXPENSES:
Fuel	0	0
Other operating expenses	12	11
Provision for depreciation	(1)	(2)
General taxes	0	0
Total operating expenses	(932)	(901)
OPERATING INCOME (LOSS)	(11)	(9)
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0
Investment income	(2)	(4)
Miscellaneous income, including net income from equity investees	(191)	(254)
Capitalized interest	0	0
Total other income (expense)	(174)	(239)
Total before taxes	(185)	(248)
INCOME TAXES (BENEFITS)	3	3
Net of tax	(188)	(251)
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(188)	(251)
Pension and OPEB prior service costs	5	4
Amortized gain (loss) on derivative hedges	0	0
Change in unrealized gain on available-for-sale securities	(5)	(10)
Other comprehensive income (loss)	0	(6)
Income taxes (benefits) on other comprehensive income (loss)	0	(2)
Net other comprehensive income (loss)	0	(4)
COMPREHENSIVE INCOME	(188)	(255)
Eliminations | Affiliates
OPERATING EXPENSES:
Purchased power	(943)	(910)
OTHER INCOME (EXPENSE):
Interest expense	3	4
Eliminations | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0
OTHER INCOME (EXPENSE):
Interest expense	16	15
FES
Consolidating Statements of Income
Revenues	1,530	1,516
OPERATING EXPENSES:
Fuel	300	295
Other operating expenses	380	295
Provision for depreciation	76	63
General taxes	37	37
Total operating expenses	1,430	1,294
OPERATING INCOME (LOSS)	100	222
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(73)	0
Investment income	17	6
Miscellaneous income, including net income from equity investees	2	4
Capitalized interest	9	9
Total other income (expense)	(96)	(24)
Total before taxes	4	198
INCOME TAXES (BENEFITS)	2	76
Net of tax	2	122
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	2	122
Pension and OPEB prior service costs	(6)	(5)
Amortized gain (loss) on derivative hedges	(1)	(5)
Change in unrealized gain on available-for-sale securities	5	10
Other comprehensive income (loss)	(2)	0
Income taxes (benefits) on other comprehensive income (loss)	(1)	2
Net other comprehensive income (loss)	(1)	(2)
COMPREHENSIVE INCOME	1	120
FES | Affiliates
OPERATING EXPENSES:
Purchased power	132	117
OTHER INCOME (EXPENSE):
Interest expense	(1)	(2)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power	505	487
OTHER INCOME (EXPENSE):
Interest expense	$ (50)	$ (41)