Supplemental Guarantor Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Consolidating Statements of Income
Revenues	$ 2,221	$ 2,323	$ 4,609	$ 4,863
OPERATING EXPENSES:
Fuel	628	656	1,258	1,197
Purchased power	862	1,042	1,805	2,301
Other operating expenses	887	921	1,771	1,739
Provision for depreciation	302	285	596	564
General taxes	241	232	506	504
Total operating expenses	3,465	3,198	6,540	6,442
OPERATING INCOME (LOSS)	54	557	708	1,303
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(24)	0	(141)	0
Investment income	(15)	13	3	24
Interest expense	(256)	(274)	(514)	(520)
Capitalized interest	19	19	34	36
Total other income (expense)	(276)	(242)	(618)	(460)
INCOME (LOSSES) BEFORE INCOME TAXES	(222)	315	90	843
INCOME TAXES (BENEFITS)	(58)	127	58	349
NET INCOME (LOSS)	(164)	188	32	494
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(164)	188	32	494
Pension and OPEB prior service costs	(55)	(48)	(101)	(101)
Amortized loss (gain) on derivative hedges	1	3	2	1
Change in unrealized gain on available-for-sale securities	(8)	2	(3)	12
Other comprehensive income (loss)	(62)	(43)	(102)	(88)
Income taxes (benefits) on other comprehensive income (loss)	(24)	(27)	(40)	(51)
Net other comprehensive income (loss)	(38)	(16)	(62)	(37)
COMPREHENSIVE INCOME (LOSS)	(202)	172	(30)	457
FES
Consolidating Statements of Income
Revenues	1,425	1,430	2,921	2,920
OPERATING EXPENSES:
Fuel	0	0	0	0
Other operating expenses	175	107	337	183
Provision for depreciation	2	1	3	2
General taxes	19	20	39	40
Total operating expenses	1,770	1,718	3,471	3,267
OPERATING INCOME (LOSS)	(345)	(288)	(550)	(347)
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(32)		(103)
Investment income	1	0	2	1
Miscellaneous income, including net income from equity investees	171	279	363	537
Capitalized interest	1	0	1	0
Total other income (expense)	124	250	219	482
INCOME (LOSSES) BEFORE INCOME TAXES	(221)	(38)	(331)	135
INCOME TAXES (BENEFITS)	(150)	(37)	(262)	14
NET INCOME (LOSS)	(71)	(1)	(69)	121
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(71)	(1)	(69)	121
Pension and OPEB prior service costs	(5)	8	(11)	3
Amortized loss (gain) on derivative hedges	(1)	1	(2)	(4)
Change in unrealized gain on available-for-sale securities	(8)	3	(3)	13
Other comprehensive income (loss)	(14)	12	(16)	12
Income taxes (benefits) on other comprehensive income (loss)	(5)	2	(6)	4
Net other comprehensive income (loss)	(9)	10	(10)	8
COMPREHENSIVE INCOME (LOSS)	(80)	9	(79)	129
FES | Affiliates
OPERATING EXPENSES:
Purchased power	1,050	1,156	2,063	2,121
OTHER INCOME (EXPENSE):
Interest expense	(5)	(5)	(7)	(9)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power	524	434	1,029	921
OTHER INCOME (EXPENSE):
Interest expense	(12)	(24)	(37)	(47)
FGCO
Consolidating Statements of Income
Revenues	560	636	1,097	1,178
OPERATING EXPENSES:
Fuel	286	336	533	576
Other operating expenses	70	100	145	192
Provision for depreciation	34	30	66	60
General taxes	8	8	19	18
Total operating expenses	398	474	763	846
OPERATING INCOME (LOSS)	162	162	334	332
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0		0
Investment income	0	5	0	9
Miscellaneous income, including net income from equity investees	3	19	4	19
Capitalized interest	0	1	0	2
Total other income (expense)	(25)	(3)	(53)	(25)
INCOME (LOSSES) BEFORE INCOME TAXES	137	159	281	307
INCOME TAXES (BENEFITS)	54	(7)	107	(8)
NET INCOME (LOSS)	83	166	174	315
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	83	166	174	315
Pension and OPEB prior service costs	(5)	7	(10)	3
Amortized loss (gain) on derivative hedges	0	0	0	0
Change in unrealized gain on available-for-sale securities	0	0	0	0
Other comprehensive income (loss)	(5)	7	(10)	3
Income taxes (benefits) on other comprehensive income (loss)	(2)	3	(4)	1
Net other comprehensive income (loss)	(3)	4	(6)	2
COMPREHENSIVE INCOME (LOSS)	80	170	168	317
FGCO | Affiliates
OPERATING EXPENSES:
Purchased power	0	0	0	0
OTHER INCOME (EXPENSE):
Interest expense	(1)	(2)	(2)	(3)
FGCO | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0	0	0
OTHER INCOME (EXPENSE):
Interest expense	(27)	(26)	(55)	(52)
Nuclear Generation Corp
Consolidating Statements of Income
Revenues	457	473	897	867
OPERATING EXPENSES:
Fuel	46	44	99	99
Other operating expenses	131	172	262	288
Provision for depreciation	44	39	88	73
General taxes	7	4	13	11
Total operating expenses	298	319	594	593
OPERATING INCOME (LOSS)	159	154	303	274
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0		0
Investment income	(14)	7	4	12
Miscellaneous income, including net income from equity investees	0	0	0	0
Capitalized interest	9	8	18	16
Total other income (expense)	(22)	0	(11)	5
INCOME (LOSSES) BEFORE INCOME TAXES	137	154	292	279
INCOME TAXES (BENEFITS)	52	42	110	65
NET INCOME (LOSS)	85	112	182	214
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	85	112	182	214
Pension and OPEB prior service costs	0	0	0	0
Amortized loss (gain) on derivative hedges	0	0	0	0
Change in unrealized gain on available-for-sale securities	(8)	3	(3)	13
Other comprehensive income (loss)	(8)	3	(3)	13
Income taxes (benefits) on other comprehensive income (loss)	(4)	1	(2)	5
Net other comprehensive income (loss)	(4)	2	(1)	8
COMPREHENSIVE INCOME (LOSS)	81	114	181	222
Nuclear Generation Corp | Affiliates
OPERATING EXPENSES:
Purchased power	70	60	132	122
OTHER INCOME (EXPENSE):
Interest expense	(3)	(1)	(4)	(2)
Nuclear Generation Corp | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0	0	0
OTHER INCOME (EXPENSE):
Interest expense	(14)	(14)	(29)	(21)
Eliminations
Consolidating Statements of Income
Revenues	(983)	(1,083)	(1,926)	(1,993)
OPERATING EXPENSES:
Fuel	0	0	0	0
Other operating expenses	12	14	24	25
Provision for depreciation	(2)	(1)	(3)	(3)
General taxes	0	0	0	0
Total operating expenses	(973)	(1,070)	(1,905)	(1,971)
OPERATING INCOME (LOSS)	(10)	(13)	(21)	(22)
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0		0
Investment income	(5)	(6)	(7)	(10)
Miscellaneous income, including net income from equity investees	(168)	(278)	(359)	(532)
Capitalized interest	0	0	0	0
Total other income (expense)	(155)	(262)	(329)	(501)
INCOME (LOSSES) BEFORE INCOME TAXES	(165)	(275)	(350)	(523)
INCOME TAXES (BENEFITS)	3	3	6	6
NET INCOME (LOSS)	(168)	(278)	(356)	(529)
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(168)	(278)	(356)	(529)
Pension and OPEB prior service costs	5	(7)	10	(3)
Amortized loss (gain) on derivative hedges	0	0	0	0
Change in unrealized gain on available-for-sale securities	8	(3)	3	(13)
Other comprehensive income (loss)	13	(10)	13	(16)
Income taxes (benefits) on other comprehensive income (loss)	6	(4)	6	(6)
Net other comprehensive income (loss)	7	(6)	7	(10)
COMPREHENSIVE INCOME (LOSS)	(161)	(284)	(349)	(539)
Eliminations | Affiliates
OPERATING EXPENSES:
Purchased power	(983)	(1,083)	(1,926)	(1,993)
OTHER INCOME (EXPENSE):
Interest expense	4	6	7	10
Eliminations | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0	0	0
OTHER INCOME (EXPENSE):
Interest expense	14	16	30	31
FES
Consolidating Statements of Income
Revenues	1,459	1,456	2,989	2,972
OPERATING EXPENSES:
Fuel	332	380	632	675
Other operating expenses	388	393	768	688
Provision for depreciation	78	69	154	132
General taxes	34	32	71	69
Total operating expenses	1,493	1,441	2,923	2,735
OPERATING INCOME (LOSS)	(34)	15	66	237
OTHER INCOME (EXPENSE):
Loss on debt redemptions	(32)	0	(103)	0
Investment income	(18)	6	(1)	12
Miscellaneous income, including net income from equity investees	6	20	8	24
Capitalized interest	10	9	19	18
Total other income (expense)	(78)	(15)	(174)	(39)
INCOME (LOSSES) BEFORE INCOME TAXES	(112)	0	(108)	198
INCOME TAXES (BENEFITS)	(41)	1	(39)	77
NET INCOME (LOSS)	(71)	(1)	(69)	121
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(71)	(1)	(69)	121
Pension and OPEB prior service costs	(5)	8	(11)	3
Amortized loss (gain) on derivative hedges	(1)	1	(2)	(4)
Change in unrealized gain on available-for-sale securities	(8)	3	(3)	13
Other comprehensive income (loss)	(14)	12	(16)	12
Income taxes (benefits) on other comprehensive income (loss)	(5)	2	(6)	4
Net other comprehensive income (loss)	(9)	10	(10)	8
COMPREHENSIVE INCOME (LOSS)	(80)	9	(79)	129
FES | Affiliates
OPERATING EXPENSES:
Purchased power	137	133	269	250
OTHER INCOME (EXPENSE):
Interest expense	(5)	(2)	(6)	(4)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power	524	434	1,029	921
OTHER INCOME (EXPENSE):
Interest expense	$ (39)	$ (48)	$ (91)	$ (89)