Supplemental Guarantor Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Consolidating Statements of Income
Revenues	$ 2,279	$ 2,590	$ 4,790	$ 4,925
OPERATING EXPENSES:
Fuel	656	635	1,197	1,088
Purchased power	1,156	1,220	2,503	2,406
Other operating expenses	914	1,065	1,726	2,058
Provision for depreciation	292	287	577	512
General taxes	232	242	504	479
Total operating expenses	3,312	3,539	6,644	6,765
OPERATING INCOME (LOSS)	557	521	1,303	871
OTHER INCOME (EXPENSE):
Investment income	13	31	24	52
Interest expense	(274)	(265)	(520)	(496)
Capitalized interest	19	20	36	38
Total other income (expense)	(242)	(214)	(460)	(406)
INCOME (LOSS) BEFORE INCOME TAXES	315	307	843	465
INCOME TAXES (BENEFITS)	127	114	349	225
NET INCOME	188	193	494	240
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	188	193	494	240
Pension and OPEB prior service costs	(48)	48	(101)	4
Amortized gain (loss) on derivative hedges	3	17	1	11
Change in unrealized gain on available-for-sale securities	2	10	12	19
Other comprehensive income (loss)	(43)	75	(88)	34
Income taxes (benefits) on other comprehensive income (loss)	(27)	33	(51)	14
Other comprehensive income (loss), net of tax	(16)	42	(37)	20
COMPREHENSIVE INCOME	172	235	457	260
FES Corp
Consolidating Statements of Income
Revenues	1,430	1,275	2,920	2,642
OPERATING EXPENSES:
Fuel	0	6	0	7
Other operating expenses	107	159	183	321
Provision for depreciation	1	1	2	2
General taxes	20	16	40	27
Impairment of long-lived assets		0		0
Total operating expenses	1,718	1,416	3,267	3,073
OPERATING INCOME (LOSS)	(288)	(141)	(347)	(431)
OTHER INCOME (EXPENSE):
Investment income	0	0	1	1
Miscellaneous income, including net income from equity investees	279	132	537	374
Capitalized interest	0	0	0	0
Total other income (expense)	250	108	482	326
INCOME (LOSS) BEFORE INCOME TAXES	(38)	(33)	135	(105)
INCOME TAXES (BENEFITS)	(37)	(62)	14	(179)
NET INCOME	(1)	29	121	74
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(1)	29	121	74
Pension and OPEB prior service costs	8	(5)	3	(9)
Amortized gain (loss) on derivative hedges	1	14	(4)	5
Change in unrealized gain on available-for-sale securities	3	8	13	15
Other comprehensive income (loss)	12	17	12	11
Income taxes (benefits) on other comprehensive income (loss)	2	8	4	4
Other comprehensive income (loss), net of tax	10	9	8	7
COMPREHENSIVE INCOME	9	38	129	81
FES Corp | Affiliates
OPERATING EXPENSES:
Purchased power	1,156	902	2,121	2,087
OTHER INCOME (EXPENSE):
Interest expense	(5)	0	(9)	(1)
FES Corp | Non-Affiliates
OPERATING EXPENSES:
Purchased power	434	332	921	629
OTHER INCOME (EXPENSE):
Interest expense	(24)	(24)	(47)	(48)
FGCO
Consolidating Statements of Income
Revenues	636	535	1,178	1,278
OPERATING EXPENSES:
Fuel	336	266	576	560
Other operating expenses	100	108	192	219
Provision for depreciation	30	32	60	63
General taxes	8	8	18	19
Impairment of long-lived assets		7		20
Total operating expenses	474	427	846	889
OPERATING INCOME (LOSS)	162	108	332	389
OTHER INCOME (EXPENSE):
Investment income	5	1	9	1
Miscellaneous income, including net income from equity investees	19	1	19	2
Capitalized interest	1	5	2	10
Total other income (expense)	(3)	(22)	(25)	(44)
INCOME (LOSS) BEFORE INCOME TAXES	159	86	307	345
INCOME TAXES (BENEFITS)	(7)	28	(8)	125
NET INCOME	166	58	315	220
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	166	58	315	220
Pension and OPEB prior service costs	7	(4)	3	(8)
Amortized gain (loss) on derivative hedges	0	0	0	0
Change in unrealized gain on available-for-sale securities	0	0	0	0
Other comprehensive income (loss)	7	(4)	3	(8)
Income taxes (benefits) on other comprehensive income (loss)	3	(2)	1	(4)
Other comprehensive income (loss), net of tax	4	(2)	2	(4)
COMPREHENSIVE INCOME	170	56	317	216
FGCO | Affiliates
OPERATING EXPENSES:
Purchased power	0	9	0	11
OTHER INCOME (EXPENSE):
Interest expense	(2)	(1)	(3)	(1)
FGCO | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	(3)	0	(3)
OTHER INCOME (EXPENSE):
Interest expense	(26)	(28)	(52)	(56)
Nuclear Generation Corp
Consolidating Statements of Income
Revenues	473	393	867	862
OPERATING EXPENSES:
Fuel	44	44	99	92
Other operating expenses	172	134	288	313
Provision for depreciation	39	37	73	76
General taxes	4	6	11	14
Impairment of long-lived assets		0		0
Total operating expenses	319	286	593	629
OPERATING INCOME (LOSS)	154	107	274	233
OTHER INCOME (EXPENSE):
Investment income	7	15	12	20
Miscellaneous income, including net income from equity investees	0	0	0	0
Capitalized interest	8	5	16	10
Total other income (expense)	0	3	5	(4)
INCOME (LOSS) BEFORE INCOME TAXES	154	110	279	229
INCOME TAXES (BENEFITS)	42	41	65	86
NET INCOME	112	69	214	143
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	112	69	214	143
Pension and OPEB prior service costs	0	0	0	0
Amortized gain (loss) on derivative hedges	0	0	0	0
Change in unrealized gain on available-for-sale securities	3	8	13	15
Other comprehensive income (loss)	3	8	13	15
Income taxes (benefits) on other comprehensive income (loss)	1	3	5	6
Other comprehensive income (loss), net of tax	2	5	8	9
COMPREHENSIVE INCOME	114	74	222	152
Nuclear Generation Corp | Affiliates
OPERATING EXPENSES:
Purchased power	60	65	122	134
OTHER INCOME (EXPENSE):
Interest expense	(1)	(1)	(2)	(1)
Nuclear Generation Corp | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0	0	0
OTHER INCOME (EXPENSE):
Interest expense	(14)	(16)	(21)	(33)
Eliminations
Consolidating Statements of Income
Revenues	(1,083)	(911)	(1,993)	(2,098)
OPERATING EXPENSES:
Fuel	0	0	0	0
Other operating expenses	14	12	25	25
Provision for depreciation	(1)	(1)	(3)	(3)
General taxes	0	0	0	0
Impairment of long-lived assets		0		0
Total operating expenses	(1,070)	(900)	(1,971)	(2,076)
OPERATING INCOME (LOSS)	(13)	(11)	(22)	(22)
OTHER INCOME (EXPENSE):
Investment income	(6)	0	(10)	0
Miscellaneous income, including net income from equity investees	(278)	(129)	(532)	(368)
Capitalized interest	0	0	0	0
Total other income (expense)	(262)	(113)	(501)	(336)
INCOME (LOSS) BEFORE INCOME TAXES	(275)	(124)	(523)	(358)
INCOME TAXES (BENEFITS)	3	3	6	5
NET INCOME	(278)	(127)	(529)	(363)
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(278)	(127)	(529)	(363)
Pension and OPEB prior service costs	(7)	4	(3)	8
Amortized gain (loss) on derivative hedges	0	0	0	0
Change in unrealized gain on available-for-sale securities	(3)	(8)	(13)	(15)
Other comprehensive income (loss)	(10)	(4)	(16)	(7)
Income taxes (benefits) on other comprehensive income (loss)	(4)	(1)	(6)	(2)
Other comprehensive income (loss), net of tax	(6)	(3)	(10)	(5)
COMPREHENSIVE INCOME	(284)	(130)	(539)	(368)
Eliminations | Affiliates
OPERATING EXPENSES:
Purchased power	(1,083)	(911)	(1,993)	(2,098)
OTHER INCOME (EXPENSE):
Interest expense	6	0	10	0
Eliminations | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0	0	0
OTHER INCOME (EXPENSE):
Interest expense	16	16	31	32
FES
Consolidating Statements of Income
Revenues	1,456	1,292	2,972	2,684
OPERATING EXPENSES:
Fuel	380	316	675	659
Other operating expenses	393	413	688	878
Provision for depreciation	69	69	132	138
General taxes	32	30	69	60
Impairment of long-lived assets	0	7	0	20
Total operating expenses	1,441	1,229	2,735	2,515
OPERATING INCOME (LOSS)	15	63	237	169
OTHER INCOME (EXPENSE):
Investment income	6	16	12	22
Miscellaneous income, including net income from equity investees	20	4	24	8
Capitalized interest	9	10	18	20
Total other income (expense)	(15)	(24)	(39)	(58)
INCOME (LOSS) BEFORE INCOME TAXES	0	39	198	111
INCOME TAXES (BENEFITS)	1	10	77	37
NET INCOME	(1)	29	121	74
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(1)	29	121	74
Pension and OPEB prior service costs	8	(5)	3	(9)
Amortized gain (loss) on derivative hedges	1	14	(4)	5
Change in unrealized gain on available-for-sale securities	3	8	13	15
Other comprehensive income (loss)	12	17	12	11
Income taxes (benefits) on other comprehensive income (loss)	2	8	4	4
Other comprehensive income (loss), net of tax	10	9	8	7
COMPREHENSIVE INCOME	9	38	129	81
FES | Affiliates
OPERATING EXPENSES:
Purchased power	133	65	250	134
OTHER INCOME (EXPENSE):
Interest expense	(2)	(2)	(4)	(3)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power	434	329	921	626
OTHER INCOME (EXPENSE):
Interest expense	$ (48)	$ (52)	$ (89)	$ (105)