Supplemental Guarantor Information (Details 1) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
CURRENT ASSETS:
Cash and cash equivalents	$ 94	$ 202	$ 476	$ 1,019
Receivables-
Customers	1,635	1,525
Other	263	269
Materials and supplies, at average cost	921	811
Derivatives	276	235
Prepayments and other	171	122
Total current assets	3,608	3,355
PROPERTY, PLANT AND EQUIPMENT:
In service	41,167	40,122
Less - Accumulated provision for depreciation	12,336	11,839
Property, plant and equipment in service net of accumulated provision for depreciation	28,831	28,283
Construction work in progress	1,937	2,054
Total net property, plant and equipment	30,768	30,337
INVESTMENTS:
Nuclear plant decommissioning trusts	2,153	2,112
Other	1,039	1,008
Total other property and investments	3,518	3,522
DEFERRED CHARGES AND OTHER ASSETS:
Goodwill	6,444	6,441	6,436
Other	1,588	1,641
Total deferred charges and other assets	10,154	10,112
Total assets	48,048	47,326	47,596
CURRENT LIABILITIES:
Currently payable long-term debt	1,577	1,621
Short-term borrowings-
Affiliated companies	1,890	0
Accounts payable-
Accrued Taxes	436	558
Derivatives	222	218
Other	617	900
Total current liabilities	6,082	4,855
CAPITALIZATION:
Total equity	13,497	13,280
Long-term debt and other long-term obligations	15,159	15,716
Total capitalization	28,671	29,015
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	909	925
Accumulated deferred income taxes	6,042	5,670
Asset retirement obligations	1,548	1,497
Retirement benefits	2,257	2,823
Other	1,980	2,072
Total noncurrent liabilities	13,295	13,456
Total liabilities and capitalization	48,048	47,326
FES Corp
CURRENT ASSETS:
Cash and cash equivalents	0	0	0	0
Receivables-
Customers	457	424
Affiliated companies	464	476
Other	67	28
Notes receivable from affiliated companies	155	155
Materials and supplies, at average cost	68	60
Derivatives	265	219
Prepayments and other	3	11
Total current assets	1,479	1,373
PROPERTY, PLANT AND EQUIPMENT:
In service	89	84
Less - Accumulated provision for depreciation	30	28
Property, plant and equipment in service net of accumulated provision for depreciation	59	56
Construction work in progress	28	29
Total net property, plant and equipment	87	85
INVESTMENTS:
Nuclear plant decommissioning trusts	0	0
Investment in affiliated companies	6,241	5,700
Other	0	0
Total other property and investments	6,241	5,700
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	0	10
Customer intangibles	118	123
Goodwill	24	24
Property taxes	0	0
Unamortized sale and leaseback costs	0	0
Derivatives	110	79
Other	86	89
Total deferred charges and other assets	338	325
Total assets	8,145	7,483
CURRENT LIABILITIES:
Currently payable long-term debt	1	1
Accounts payable-
Affiliated companies	739	777
Other	173	99
Accrued Taxes	23	84
Derivatives	219	189
Other	68	62
Total current liabilities	2,820	2,277
CAPITALIZATION:
Total equity	3,704	3,577
Long-term debt and other long-term obligations	1,482	1,483
Total capitalization	5,186	5,060
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	0	0
Accumulated deferred income taxes	28	12
Asset retirement obligations	0	0
Retirement benefits	34	56
Lease market valuation liability	0	0
Other	77	78
Total noncurrent liabilities	139	146
Total liabilities and capitalization	8,145	7,483
FGCO
CURRENT ASSETS:
Cash and cash equivalents	7	7	6	9
Receivables-
Customers	0	0
Affiliated companies	482	643
Other	25	20
Notes receivable from affiliated companies	1,653	1,346
Materials and supplies, at average cost	272	232
Derivatives	0	0
Prepayments and other	15	26
Total current assets	2,454	2,274
PROPERTY, PLANT AND EQUIPMENT:
In service	5,620	5,573
Less - Accumulated provision for depreciation	1,872	1,813
Property, plant and equipment in service net of accumulated provision for depreciation	3,748	3,760
Construction work in progress	187	195
Total net property, plant and equipment	3,935	3,955
INVESTMENTS:
Nuclear plant decommissioning trusts	0	0
Investment in affiliated companies	0	0
Other	7	7
Total other property and investments	7	7
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	261	307
Customer intangibles		0
Goodwill		0
Property taxes	20	20
Unamortized sale and leaseback costs	4	5
Derivatives		0
Other	160	99
Total deferred charges and other assets	445	431
Total assets	6,841	6,667
CURRENT LIABILITIES:
Currently payable long-term debt	646	411
Accounts payable-
Affiliated companies	279	228
Other	133	121
Accrued Taxes	20	42
Derivatives	0	0
Other	124	141
Total current liabilities	1,337	1,032
CAPITALIZATION:
Total equity	3,413	3,097
Long-term debt and other long-term obligations	1,657	1,905
Total capitalization	5,070	5,002
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	0	0
Accumulated deferred income taxes	0	0
Asset retirement obligations	29	28
Retirement benefits	145	300
Lease market valuation liability	148	171
Other	112	134
Total noncurrent liabilities	434	633
Total liabilities and capitalization	6,841	6,667
Nuclear Generation Corp
CURRENT ASSETS:
Cash and cash equivalents	0	0	0	0
Receivables-
Customers	0	0
Affiliated companies	297	262
Other	4	13
Notes receivable from affiliated companies	152	69
Materials and supplies, at average cost	208	200
Derivatives	0	0
Prepayments and other	1	1
Total current assets	662	545
PROPERTY, PLANT AND EQUIPMENT:
In service	6,051	5,711
Less - Accumulated provision for depreciation	2,594	2,449
Property, plant and equipment in service net of accumulated provision for depreciation	3,457	3,262
Construction work in progress	704	790
Total net property, plant and equipment	4,161	4,052
INVESTMENTS:
Nuclear plant decommissioning trusts	1,250	1,223
Investment in affiliated companies	0	0
Other	0	0
Total other property and investments	1,250	1,223
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	0	0
Customer intangibles	0	0
Goodwill	0	0
Property taxes	23	23
Unamortized sale and leaseback costs	0	0
Derivatives	0	0
Other	1	3
Total deferred charges and other assets	24	26
Total assets	6,097	5,846
CURRENT LIABILITIES:
Currently payable long-term debt	518	513
Accounts payable-
Affiliated companies	305	211
Other	0	0
Accrued Taxes	27	110
Derivatives	0	0
Other	13	16
Total current liabilities	863	882
CAPITALIZATION:
Total equity	2,810	2,587
Long-term debt and other long-term obligations	580	641
Total capitalization	3,390	3,228
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	0	0
Accumulated deferred income taxes	572	510
Asset retirement obligations	905	876
Retirement benefits	0	0
Lease market valuation liability	0	0
Other	367	350
Total noncurrent liabilities	1,844	1,736
Total liabilities and capitalization	6,097	5,846
Eliminations
CURRENT ASSETS:
Cash and cash equivalents	0	0	0	0
Receivables-
Customers	0	0
Affiliated companies	(706)	(781)
Other	0	0
Notes receivable from affiliated companies	(1,732)	(1,187)
Materials and supplies, at average cost	0	0
Derivatives	0	0
Prepayments and other	0	0
Total current assets	(2,438)	(1,968)
PROPERTY, PLANT AND EQUIPMENT:
In service	(385)	(385)
Less - Accumulated provision for depreciation	(182)	(180)
Property, plant and equipment in service net of accumulated provision for depreciation	(203)	(205)
Construction work in progress	0	0
Total net property, plant and equipment	(203)	(205)
INVESTMENTS:
Nuclear plant decommissioning trusts	0	0
Investment in affiliated companies	(6,241)	(5,700)
Other	0	0
Total other property and investments	(6,241)	(5,700)
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	(261)	(317)
Customer intangibles	0	0
Goodwill	0	0
Property taxes	0	0
Unamortized sale and leaseback costs	114	75
Derivatives	0	0
Other	(110)	(62)
Total deferred charges and other assets	(257)	(304)
Total assets	(9,139)	(8,177)
CURRENT LIABILITIES:
Currently payable long-term debt	(21)	(20)
Accounts payable-
Affiliated companies	(715)	(780)
Other	0	0
Accrued Taxes	(8)	(9)
Derivatives	0	0
Other	37	42
Total current liabilities	(2,439)	(1,953)
CAPITALIZATION:
Total equity	(6,223)	(5,684)
Long-term debt and other long-term obligations	(1,219)	(1,230)
Total capitalization	(7,442)	(6,914)
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	909	925
Accumulated deferred income taxes	(164)	(236)
Asset retirement obligations	0	0
Retirement benefits	0	0
Lease market valuation liability	0	0
Other	(3)	1
Total noncurrent liabilities	742	690
Total liabilities and capitalization	(9,139)	(8,177)
FES
CURRENT ASSETS:
Cash and cash equivalents	7	7	6	9
Receivables-
Customers	457	424
Affiliated companies	537	600
Other	96	61
Notes receivable from affiliated companies	228	383
Materials and supplies, at average cost	548	492
Derivatives	265	219
Prepayments and other	19	38
Total current assets	2,157	2,224
PROPERTY, PLANT AND EQUIPMENT:
In service	11,375	10,983
Less - Accumulated provision for depreciation	4,314	4,110
Property, plant and equipment in service net of accumulated provision for depreciation	7,061	6,873
Construction work in progress	919	1,014
Total net property, plant and equipment	7,980	7,887
INVESTMENTS:
Nuclear plant decommissioning trusts	1,250	1,223
Investment in affiliated companies	0	0
Other	7	7
Total other property and investments	1,257	1,230
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	0	0
Customer intangibles	118	123
Goodwill	24	24
Property taxes	43	43
Unamortized sale and leaseback costs	118	80
Derivatives	110	79
Other	137	129
Total deferred charges and other assets	550	478
Total assets	11,944	11,819
CURRENT LIABILITIES:
Currently payable long-term debt	1,144	905
Accounts payable-
Affiliated companies	608	436
Other	306	220
Accrued Taxes	62	227
Derivatives	219	189
Other	242	261
Total current liabilities	2,581	2,238
CAPITALIZATION:
Total equity	3,704	3,577
Long-term debt and other long-term obligations	2,500	2,799
Total capitalization	6,204	6,376
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	909	925
Accumulated deferred income taxes	436	286
Asset retirement obligations	934	904
Retirement benefits	179	356
Lease market valuation liability	148	171
Other	553	563
Total noncurrent liabilities	3,159	3,205
Total liabilities and capitalization	11,944	11,819
Affiliates | FES Corp
Short-term borrowings-
Affiliated companies	1,597	1,065
Affiliates | FGCO
Short-term borrowings-
Affiliated companies	135	89
Affiliates | Nuclear Generation Corp
Short-term borrowings-
Affiliated companies	0	32
Affiliates | Eliminations
Short-term borrowings-
Affiliated companies	(1,732)	(1,186)
Affiliates | FES
Short-term borrowings-
Affiliated companies	$ 0	$ 0