Supplemental Guarantor Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Consolidating Statements of Income
Revenues	$ 2,530	$ 2,670	$ 7,139	$ 7,533
OPERATING EXPENSES:
Fuel	657	636	1,915	1,833
Purchased power	1,120	1,063	2,932	3,367
Other operating expenses	877	861	2,645	2,597
Provision for depreciation	316	272	909	834
General taxes	242	257	747	760
Total operating expenses	3,524	3,150	10,064	9,589
OPERATING INCOME (LOSS)	512	902	1,206	2,191
OTHER INCOME (EXPENSE):
Loss on debt redemptions	9	0	(132)	0
Investment income	5	39	8	63
Interest expense	(257)	(230)	(771)	(750)
Capitalized interest	17	18	51	54
Total other income (expense)	(226)	(173)	(844)	(633)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	286	729	362	1,558
INCOME TAXES (BENEFITS)	77	307	129	650
NET INCOME FROM CONTINUING OPERATIONS	209	422	233	908
Discontinued operations (Note 16)	9	3	17	11
NET INCOME (LOSS)	218	425	250	919
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	218	425	250	919
Pension and OPEB prior service costs	(47)	(47)	(148)	(148)
Amortized loss (gain) on derivative hedges	2	0	4	1
Change in unrealized gain on available-for-sale securities	6	1	3	13
Other comprehensive income (loss)	(39)	(46)	(141)	(134)
Income taxes (benefits) on other comprehensive income (loss)	(15)	(24)	(55)	(75)
Net other comprehensive income (loss)	(24)	(22)	(86)	(59)
COMPREHENSIVE INCOME (LOSS)	194	403	164	860
FES
Consolidating Statements of Income
Revenues	1,654	1,523	4,575	4,443
OPERATING EXPENSES:
Fuel	0	0	0	0
Other operating expenses	147	130	484	313
Provision for depreciation	1	1	4	3
General taxes	21	20	60	60
Total operating expenses	1,898	1,692	5,369	4,959
OPERATING INCOME (LOSS)	(244)	(169)	(794)	(516)
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0		(103)
Investment income	2	1	4	2
Miscellaneous income, including net income from equity investees	180	317	543	854
Capitalized interest	0	0	1	0
Total other income (expense)	166	288	385	770
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(78)	119	(409)	254
INCOME TAXES (BENEFITS)	(118)	18	(380)	32
NET INCOME FROM CONTINUING OPERATIONS	40	101	(29)	222
Discontinued operations (Note 16)	0	0	0	0
NET INCOME (LOSS)	40	101	(29)	222
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	40	101	(29)	222
Pension and OPEB prior service costs	(5)	(5)	(16)	(2)
Amortized loss (gain) on derivative hedges	(1)	(2)	(3)	(6)
Change in unrealized gain on available-for-sale securities	5	(2)	2	11
Other comprehensive income (loss)	(1)	(9)	(17)	3
Income taxes (benefits) on other comprehensive income (loss)	(1)	(3)	(7)	1
Net other comprehensive income (loss)	0	(6)	(10)	2
COMPREHENSIVE INCOME (LOSS)	40	95	(39)	224
FES | Affiliates
OPERATING EXPENSES:
Purchased power	1,009	1,042	3,072	3,163
OTHER INCOME (EXPENSE):
Interest expense	(3)	(5)	(10)	(14)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power	720	499	1,749	1,420
OTHER INCOME (EXPENSE):
Interest expense	(13)	(25)	(50)	(72)
FGCO
Consolidating Statements of Income
Revenues	528	610	1,612	1,777
OPERATING EXPENSES:
Fuel	249	248	782	824
Other operating expenses	65	78	208	268
Provision for depreciation	33	29	96	87
General taxes	9	10	28	28
Total operating expenses	360	368	1,120	1,212
OPERATING INCOME (LOSS)	168	242	492	565
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0		0
Investment income	0	5	0	14
Miscellaneous income, including net income from equity investees	19	0	23	19
Capitalized interest	1	1	1	3
Total other income (expense)	(6)	(23)	(59)	(48)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	162	219	433	517
INCOME TAXES (BENEFITS)	111	(14)	215	(25)
NET INCOME FROM CONTINUING OPERATIONS	51	233	218	542
Discontinued operations (Note 16)	7	5	14	11
NET INCOME (LOSS)	58	238	232	553
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	58	238	232	553
Pension and OPEB prior service costs	(5)	(4)	(15)	(1)
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)	(4)	(15)	(1)
Income taxes (benefits) on other comprehensive income (loss)	(2)	(2)	(6)	(1)
Net other comprehensive income (loss)	(3)	(2)	(9)	0
COMPREHENSIVE INCOME (LOSS)	55	236	223	553
FGCO | Affiliates
OPERATING EXPENSES:
Purchased power	0	0	0	0
OTHER INCOME (EXPENSE):
Interest expense	(2)	(2)	(4)	(5)
FGCO | Non-Affiliates
OPERATING EXPENSES:
Purchased power	4	3	6	5
OTHER INCOME (EXPENSE):
Interest expense	(24)	(27)	(79)	(79)
Nuclear Generation Corp
Consolidating Statements of Income
Revenues	440	395	1,337	1,262
OPERATING EXPENSES:
Fuel	55	55	154	154
Other operating expenses	114	122	376	410
Provision for depreciation	46	41	134	114
General taxes	5	5	18	16
Total operating expenses	285	290	879	883
OPERATING INCOME (LOSS)	155	105	458	379
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0		0
Investment income	(1)	37	3	49
Miscellaneous income, including net income from equity investees	0	0	0	0
Capitalized interest	8	8	26	24
Total other income (expense)	(7)	29	(18)	34
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	148	134	440	413
INCOME TAXES (BENEFITS)	28	59	138	124
NET INCOME FROM CONTINUING OPERATIONS	120	75	302	289
Discontinued operations (Note 16)	0	0	0	0
NET INCOME (LOSS)	120	75	302	289
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	120	75	302	289
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	5	(1)	2	12
Other comprehensive income (loss)	5	(1)	2	12
Income taxes (benefits) on other comprehensive income (loss)	3	0	1	5
Net other comprehensive income (loss)	2	(1)	1	7
COMPREHENSIVE INCOME (LOSS)	122	74	303	296
Nuclear Generation Corp | Affiliates
OPERATING EXPENSES:
Purchased power	65	67	197	189
OTHER INCOME (EXPENSE):
Interest expense	(1)	(1)	(5)	(3)
Nuclear Generation Corp | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0	0	0
OTHER INCOME (EXPENSE):
Interest expense	(13)	(15)	(42)	(36)
Eliminations
Consolidating Statements of Income
Revenues	(943)	(978)	(2,869)	(2,971)
OPERATING EXPENSES:
Fuel	0	0	0	0
Other operating expenses	13	12	37	37
Provision for depreciation	0	(1)	(3)	(4)
General taxes	0	0	0	0
Total operating expenses	(929)	(967)	(2,834)	(2,938)
OPERATING INCOME (LOSS)	(14)	(11)	(35)	(33)
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0		0
Investment income	(4)	(5)	(11)	(15)
Miscellaneous income, including net income from equity investees	(178)	(316)	(537)	(848)
Capitalized interest	0	0	0	0
Total other income (expense)	(162)	(300)	(491)	(801)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(176)	(311)	(526)	(834)
INCOME TAXES (BENEFITS)	2	2	8	8
NET INCOME FROM CONTINUING OPERATIONS	(178)	(313)	(534)	(842)
Discontinued operations (Note 16)	0	0	0	0
NET INCOME (LOSS)	(178)	(313)	(534)	(842)
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	(178)	(313)	(534)	(842)
Pension and OPEB prior service costs	5	4	15	1
Amortized loss (gain) on derivative hedges	0	0	0	0
Change in unrealized gain on available-for-sale securities	(5)	1	(2)	(12)
Other comprehensive income (loss)	0	5	13	(11)
Income taxes (benefits) on other comprehensive income (loss)	(1)	2	5	(4)
Net other comprehensive income (loss)	1	3	8	(7)
COMPREHENSIVE INCOME (LOSS)	(177)	(310)	(526)	(849)
Eliminations | Affiliates
OPERATING EXPENSES:
Purchased power	(942)	(978)	(2,868)	(2,971)
OTHER INCOME (EXPENSE):
Interest expense	5	5	12	15
Eliminations | Non-Affiliates
OPERATING EXPENSES:
Purchased power	0	0	0	0
OTHER INCOME (EXPENSE):
Interest expense	15	16	45	47
FES
Consolidating Statements of Income
Revenues	1,679	1,550	4,655	4,511
OPERATING EXPENSES:
Fuel	304	303	936	978
Other operating expenses	339	342	1,105	1,028
Provision for depreciation	80	70	231	200
General taxes	35	35	106	104
Total operating expenses	1,614	1,383	4,534	4,116
OPERATING INCOME (LOSS)	65	167	121	395
OTHER INCOME (EXPENSE):
Loss on debt redemptions	0	0	(103)	0
Investment income	(3)	38	(4)	50
Miscellaneous income, including net income from equity investees	21	1	29	25
Capitalized interest	9	9	28	27
Total other income (expense)	(9)	(6)	(183)	(45)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	56	161	(62)	350
INCOME TAXES (BENEFITS)	23	65	(19)	139
NET INCOME FROM CONTINUING OPERATIONS	33	96	(43)	211
Discontinued operations (Note 16)	7	5	14	11
NET INCOME (LOSS)	40	101	(29)	222
OTHER COMPREHENSIVE INCOME (LOSS):
NET INCOME	40	101	(29)	222
Pension and OPEB prior service costs	(5)	(5)	(16)	(2)
Amortized loss (gain) on derivative hedges	(1)	(2)	(3)	(6)
Change in unrealized gain on available-for-sale securities	5	(2)	2	11
Other comprehensive income (loss)	(1)	(9)	(17)	3
Income taxes (benefits) on other comprehensive income (loss)	(1)	(3)	(7)	1
Net other comprehensive income (loss)	0	(6)	(10)	2
COMPREHENSIVE INCOME (LOSS)	40	95	(39)	224
FES | Affiliates
OPERATING EXPENSES:
Purchased power	132	131	401	381
OTHER INCOME (EXPENSE):
Interest expense	(1)	(3)	(7)	(7)
FES | Non-Affiliates
OPERATING EXPENSES:
Purchased power	724	502	1,755	1,425
OTHER INCOME (EXPENSE):
Interest expense	$ (35)	$ (51)	$ (126)	$ (140)