Supplemental Guarantor Information (Details 1) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
CURRENT ASSETS:
Cash and cash equivalents	$ 94	$ 85	$ 76	$ 218
Receivables-
Customers	1,590	1,554
Other	181	225
Materials and supplies	792	817
Derivatives	171	159
Collateral	141	230
Prepayments and other	166	160
Total current assets	4,113	3,876
PROPERTY, PLANT AND EQUIPMENT:
In service	48,862	47,484
Less - Accumulated provision for depreciation	14,728	14,150
Property, plant and equipment in service net of accumulated provision for depreciation	34,134	33,334
Construction work in progress	2,282	2,449
Total net property, plant and equipment	36,416	35,783
INVESTMENTS:
Nuclear plant decommissioning trusts	2,348	2,341
Other	886	881
Total other property and investments	3,234	3,222
DEFERRED CHARGES AND OTHER ASSETS:
Goodwill	6,418	6,418	6,418
Other	1,301	1,456
Total deferred charges and other assets	9,242	9,285
Total assets	53,005	52,166	51,388
CURRENT LIABILITIES:
Currently payable long-term debt	1,292	804
Other	2,908	1,799
Accounts payable-
Accrued taxes	467	490
Derivatives	160	167
Other	605	693
Total current liabilities	6,789	5,561
CAPITALIZATION:
Total common stockholders' equity	12,530	12,420
Long-term debt and other long-term obligations	18,570	19,176
Total capitalization	31,101	31,598
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	807	824
Accumulated deferred income taxes	7,485	7,057
Asset retirement obligations	1,411	1,387
Retirement benefits	3,836	3,932
Other	1,373	1,590
Total noncurrent liabilities	15,115	15,007
Total liabilities and capitalization	53,005	52,166
FES
CURRENT ASSETS:
Cash and cash equivalents	0	0	0	0
Receivables-
Customers	325	415
Affiliated companies	340	484
Other	45	66
Notes receivable from affiliated companies	394	339
Materials and supplies	54	67
Derivatives	158	147
Collateral	140	229
Prepayments and other	80	56
Total current assets	1,536	1,803
PROPERTY, PLANT AND EQUIPMENT:
In service	90	133
Less - Accumulated provision for depreciation	34	36
Property, plant and equipment in service net of accumulated provision for depreciation	56	97
Construction work in progress	3	3
Total net property, plant and equipment	59	100
INVESTMENTS:
Nuclear plant decommissioning trusts	0	0
Investment in affiliated companies	6,957	6,607
Other	0	0
Total other property and investments	6,957	6,607
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	322	276
Customer intangibles	70	78
Goodwill	23	23
Property taxes	0	0
Unamortized sale and leaseback costs	0	0
Derivatives	104	52
Other	51	34
Total deferred charges and other assets	570	463
Total assets	9,122	8,973
CURRENT LIABILITIES:
Currently payable long-term debt	0	18
Other	250	90
Accounts payable-
Affiliated companies	581	1,068
Other	24	46
Accrued taxes	3	2
Derivatives	155	166
Other	66	72
Total current liabilities	2,728	2,597
CAPITALIZATION:
Total common stockholders' equity	5,554	5,585
Long-term debt and other long-term obligations	695	695
Total capitalization	6,249	6,280
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	0	0
Accumulated deferred income taxes	7	13
Asset retirement obligations	0	0
Retirement benefits	36	36
Derivatives	69	14
Other	33	33
Total noncurrent liabilities	145	96
Total liabilities and capitalization	9,122	8,973
FES | Affiliates
CURRENT LIABILITIES:
Short-term borrowings	1,649	1,135
FGCO
CURRENT ASSETS:
Cash and cash equivalents	2	2	2	2
Receivables-
Customers	0	0
Affiliated companies	287	487
Other	2	21
Notes receivable from affiliated companies	1,072	838
Materials and supplies	201	202
Derivatives	0	0
Collateral	0	0
Prepayments and other	59	41
Total current assets	1,623	1,591
PROPERTY, PLANT AND EQUIPMENT:
In service	6,351	6,217
Less - Accumulated provision for depreciation	2,107	2,058
Property, plant and equipment in service net of accumulated provision for depreciation	4,244	4,159
Construction work in progress	157	206
Total net property, plant and equipment	4,401	4,365
INVESTMENTS:
Nuclear plant decommissioning trusts	0	0
Investment in affiliated companies	0	0
Other	10	10
Total other property and investments	10	10
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	0	76
Customer intangibles	0	0
Goodwill	0	0
Property taxes	7	14
Unamortized sale and leaseback costs	0	0
Derivatives	0	0
Other	321	277
Total deferred charges and other assets	328	367
Total assets	6,362	6,333
CURRENT LIABILITIES:
Currently payable long-term debt	167	164
Other	8	9
Accounts payable-
Affiliated companies	133	197
Other	93	202
Accrued taxes	41	62
Derivatives	3	0
Other	54	56
Total current liabilities	883	1,011
CAPITALIZATION:
Total common stockholders' equity	2,712	2,561
Long-term debt and other long-term obligations	2,199	2,215
Total capitalization	4,911	4,776
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	0	0
Accumulated deferred income taxes	29	0
Asset retirement obligations	191	189
Retirement benefits	295	288
Derivatives	5	0
Other	48	69
Total noncurrent liabilities	568	546
Total liabilities and capitalization	6,362	6,333
FGCO | Affiliates
CURRENT LIABILITIES:
Short-term borrowings	384	321
Nuclear Generation Corp
CURRENT ASSETS:
Cash and cash equivalents	0	0	0	0
Receivables-
Customers	0	0
Affiliated companies	301	674
Other	10	20
Notes receivable from affiliated companies	580	272
Materials and supplies	221	223
Derivatives	0	0
Collateral	0	0
Prepayments and other	0	0
Total current assets	1,112	1,189
PROPERTY, PLANT AND EQUIPMENT:
In service	7,919	7,628
Less - Accumulated provision for depreciation	3,483	3,305
Property, plant and equipment in service net of accumulated provision for depreciation	4,436	4,323
Construction work in progress	757	801
Total net property, plant and equipment	5,193	5,124
INVESTMENTS:
Nuclear plant decommissioning trusts	1,365	1,365
Investment in affiliated companies	0	0
Other	0	0
Total other property and investments	1,365	1,365
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	0	0
Customer intangibles	0	0
Goodwill	0	0
Property taxes	12	27
Unamortized sale and leaseback costs	0	0
Derivatives	0	0
Other	11	7
Total deferred charges and other assets	23	34
Total assets	7,693	7,712
CURRENT LIABILITIES:
Currently payable long-term debt	541	348
Other	0	0
Accounts payable-
Affiliated companies	164	219
Other	0	0
Accrued taxes	50	161
Derivatives	0	0
Other	9	9
Total current liabilities	764	765
CAPITALIZATION:
Total common stockholders' equity	4,208	4,014
Long-term debt and other long-term obligations	614	859
Total capitalization	4,822	4,873
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	0	0
Accumulated deferred income taxes	696	678
Asset retirement obligations	659	652
Retirement benefits	0	0
Derivatives	0	0
Other	752	744
Total noncurrent liabilities	2,107	2,074
Total liabilities and capitalization	7,693	7,712
Nuclear Generation Corp | Affiliates
CURRENT LIABILITIES:
Short-term borrowings	0	28
Eliminations
CURRENT ASSETS:
Cash and cash equivalents	0	0	0	0
Receivables-
Customers	0	0
Affiliated companies	(525)	(1,120)
Other	0	0
Notes receivable from affiliated companies	(2,033)	(1,449)
Materials and supplies	0	0
Derivatives	0	0
Collateral	0	0
Prepayments and other	0	(2)
Total current assets	(2,558)	(2,571)
PROPERTY, PLANT AND EQUIPMENT:
In service	(382)	(382)
Less - Accumulated provision for depreciation	(193)	(191)
Property, plant and equipment in service net of accumulated provision for depreciation	(189)	(191)
Construction work in progress	0	0
Total net property, plant and equipment	(189)	(191)
INVESTMENTS:
Nuclear plant decommissioning trusts	0	0
Investment in affiliated companies	(6,957)	(6,607)
Other	0	0
Total other property and investments	(6,957)	(6,607)
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	(322)	(352)
Customer intangibles	0	0
Goodwill	0	0
Property taxes	0	0
Unamortized sale and leaseback costs	266	217
Derivatives	0	0
Other	(266)	(204)
Total deferred charges and other assets	(322)	(339)
Total assets	(10,026)	(9,708)
CURRENT LIABILITIES:
Currently payable long-term debt	(25)	(24)
Other	0	0
Accounts payable-
Affiliated companies	(581)	(1,068)
Other	0	0
Accrued taxes	(15)	(123)
Derivatives	0	0
Other	34	47
Total current liabilities	(2,620)	(2,617)
CAPITALIZATION:
Total common stockholders' equity	(6,920)	(6,575)
Long-term debt and other long-term obligations	(1,149)	(1,161)
Total capitalization	(8,069)	(7,736)
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	807	824
Accumulated deferred income taxes	(144)	(180)
Asset retirement obligations	0	0
Retirement benefits	0	0
Derivatives	0	0
Other	0	1
Total noncurrent liabilities	663	645
Total liabilities and capitalization	(10,026)	(9,708)
Eliminations | Affiliates
CURRENT LIABILITIES:
Short-term borrowings	(2,033)	(1,449)
FES
CURRENT ASSETS:
Cash and cash equivalents	2	2	$ 2	$ 2
Receivables-
Customers	325	415
Affiliated companies	403	525
Other	57	107
Notes receivable from affiliated companies	13	0
Materials and supplies	476	492
Derivatives	158	147
Collateral	140	229
Prepayments and other	139	95
Total current assets	1,713	2,012
PROPERTY, PLANT AND EQUIPMENT:
In service	13,978	13,596
Less - Accumulated provision for depreciation	5,431	5,208
Property, plant and equipment in service net of accumulated provision for depreciation	8,547	8,388
Construction work in progress	917	1,010
Total net property, plant and equipment	9,464	9,398
INVESTMENTS:
Nuclear plant decommissioning trusts	1,365	1,365
Investment in affiliated companies	0	0
Other	10	10
Total other property and investments	1,375	1,375
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	0	0
Customer intangibles	70	78
Goodwill	23	23
Property taxes	19	41
Unamortized sale and leaseback costs	266	217
Derivatives	104	52
Other	117	114
Total deferred charges and other assets	599	525
Total assets	13,151	13,310
CURRENT LIABILITIES:
Currently payable long-term debt	683	506
Other	258	99
Accounts payable-
Affiliated companies	297	416
Other	117	248
Accrued taxes	79	102
Derivatives	158	166
Other	163	184
Total current liabilities	1,755	1,756
CAPITALIZATION:
Total common stockholders' equity	5,554	5,585
Long-term debt and other long-term obligations	2,359	2,608
Total capitalization	7,913	8,193
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	807	824
Accumulated deferred income taxes	588	511
Asset retirement obligations	850	841
Retirement benefits	331	324
Derivatives	74	14
Other	833	847
Total noncurrent liabilities	3,483	3,361
Total liabilities and capitalization	13,151	13,310
FES | Affiliates
CURRENT LIABILITIES:
Short-term borrowings	$ 0	$ 35