Supplemental Guarantor Information (Details 1) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CURRENT ASSETS:
Cash and cash equivalents	$ 199	$ 131	$ 85	$ 218
Receivables-
Customers	1,440	1,415
Other Receivables	175	180
Materials and supplies, at average cost	564	785
Derivatives	140	157
Collateral	176	70
Prepayments and other	158	167
Total current assets	2,950	3,040
PROPERTY, PLANT AND EQUIPMENT:
In service	43,767	49,952
Less — Accumulated provision for depreciation	15,731	15,160
Property, plant and equipment in service net of accumulated provision for depreciation	28,036	34,792
Construction work in progress	1,351	2,422
Total net property, plant and equipment	29,387	37,214
INVESTMENTS:
Nuclear plant decommissioning trusts	2,514	2,282
Other	512	506
Total other property and investments	3,026	2,788
DEFERRED CHARGES AND OTHER ASSETS:
Customer intangibles	120
Goodwill	5,618	6,418	6,418
Other	1,153	1,286
Total deferred charges and other assets	7,785	9,052
Total assets	43,148	52,094	51,552
CURRENT LIABILITIES:
Currently payable long-term debt	1,685	1,166
Short-term borrowings	2,675	1,708
Accounts payable-
Accrued taxes	580	519
Derivatives	78	106
Other	660	642
Total current liabilities	7,126	5,602
CAPITALIZATION:
Total equity	6,241	12,421
Long-term debt and other long-term obligations	18,192	19,099
Total capitalization	24,433	31,521
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	757	791
Accumulated deferred income taxes	3,765	6,773
Retirement benefits	3,719	4,245
Asset retirement obligations	1,482	1,410
Other	1,704	1,555
Total noncurrent liabilities	11,589	14,971
Total liabilities and capitalization	43,148	52,094
Eliminations
CURRENT ASSETS:
Cash and cash equivalents	0	0	0	0
Receivables-
Customers	0	0
Affiliated companies	(612)	(846)
Other Receivables	0	0
Notes receivable from affiliated companies	(3,351)	(2,410)
Materials and supplies, at average cost	0	0
Derivatives	0	0
Collateral	0	0
Prepayments and other	0	0
Total current assets	(3,963)	(3,256)
PROPERTY, PLANT AND EQUIPMENT:
In service	(290)	(382)
Less — Accumulated provision for depreciation	(187)	(194)
Property, plant and equipment in service net of accumulated provision for depreciation	(103)	(188)
Construction work in progress	0	0
Total net property, plant and equipment	(103)	(188)
INVESTMENTS:
Nuclear plant decommissioning trusts	0	0
Investment in affiliated companies	(2,923)	(7,452)
Other	0	0
Total other property and investments	(2,923)	(7,452)
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	(270)	(316)
Customer intangibles	0	0
Goodwill		0
Property taxes	0	0
Derivatives	0	0
Other	21	12
Total deferred charges and other assets	(249)	(304)
Total assets	(7,238)	(11,200)
CURRENT LIABILITIES:
Currently payable long-term debt	(26)	(25)
Short-term borrowings	0	0
Accounts payable-
Affiliated companies	(706)	(856)
Other	0	0
Accrued taxes	(16)	(86)
Derivatives	0	0
Other	36	45
Total current liabilities	(4,063)	(3,332)
CAPITALIZATION:
Total equity	(2,834)	(7,420)
Long-term debt and other long-term obligations	(1,091)	(1,136)
Total capitalization	(3,925)	(8,556)
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	757	791
Accumulated deferred income taxes	(7)	(103)
Retirement benefits	0	0
Asset retirement obligations	0	0
Derivatives	0	0
Other	0	0
Total noncurrent liabilities	750	688
Total liabilities and capitalization	(7,238)	(11,200)
Eliminations | Affiliates
CURRENT LIABILITIES:
Other Short-term Borrowings	(3,351)	(2,410)
FES
CURRENT ASSETS:
Cash and cash equivalents	0	0	0	0
Receivables-
Customers	213	275
Affiliated companies	332	433
Other Receivables	17	36
Notes receivable from affiliated companies	501	406
Materials and supplies, at average cost	45	53
Derivatives	137	154
Collateral	157	70
Prepayments and other	38	48
Total current assets	1,440	1,475
PROPERTY, PLANT AND EQUIPMENT:
In service	120	93
Less — Accumulated provision for depreciation	52	40
Property, plant and equipment in service net of accumulated provision for depreciation	68	53
Construction work in progress	2	30
Total net property, plant and equipment	70	83
INVESTMENTS:
Nuclear plant decommissioning trusts	0	0
Investment in affiliated companies	2,923	7,452
Other	0	0
Total other property and investments	2,923	7,452
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	395	300
Customer intangibles	9	61
Goodwill		23
Property taxes	0	0
Derivatives	77	79
Other	24	29
Total deferred charges and other assets	505	492
Total assets	4,938	9,502
CURRENT LIABILITIES:
Currently payable long-term debt	0	0
Short-term borrowings	0	0
Accounts payable-
Affiliated companies	743	884
Other	17	21
Accrued taxes	50	7
Derivatives	71	103
Other	56	66
Total current liabilities	3,906	3,102
CAPITALIZATION:
Total equity	218	5,605
Long-term debt and other long-term obligations	691	690
Total capitalization	909	6,295
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	0	0
Accumulated deferred income taxes	4	6
Retirement benefits	25	27
Asset retirement obligations	0	0
Derivatives	52	37
Other	42	35
Total noncurrent liabilities	123	105
Total liabilities and capitalization	4,938	9,502
FES | Affiliates
CURRENT LIABILITIES:
Other Short-term Borrowings	2,969	2,021
FG
CURRENT ASSETS:
Cash and cash equivalents	2	2	2	2
Receivables-
Customers	0	0
Affiliated companies	315	403
Other Receivables	2	4
Notes receivable from affiliated companies	1,585	1,210
Materials and supplies, at average cost	142	204
Derivatives	0	0
Collateral	0	0
Prepayments and other	24	18
Total current assets	2,070	1,841
PROPERTY, PLANT AND EQUIPMENT:
In service	2,524	6,367
Less — Accumulated provision for depreciation	1,920	2,144
Property, plant and equipment in service net of accumulated provision for depreciation	604	4,223
Construction work in progress	67	249
Total net property, plant and equipment	671	4,472
INVESTMENTS:
Nuclear plant decommissioning trusts	0	0
Investment in affiliated companies	0	0
Other	9	10
Total other property and investments	9	10
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	1,271	16
Customer intangibles	0	0
Goodwill		0
Property taxes	12	12
Derivatives	0	0
Other	327	312
Total deferred charges and other assets	1,610	340
Total assets	4,360	6,663
CURRENT LIABILITIES:
Currently payable long-term debt	200	229
Short-term borrowings	0	8
Accounts payable-
Affiliated companies	107	146
Other	93	118
Accrued taxes	48	93
Derivatives	6	1
Other	54	61
Total current liabilities	991	1,045
CAPITALIZATION:
Total equity	828	2,944
Long-term debt and other long-term obligations	2,093	2,116
Total capitalization	2,921	5,060
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	0	0
Accumulated deferred income taxes	3	0
Retirement benefits	172	305
Asset retirement obligations	188	191
Derivatives	0	1
Other	85	61
Total noncurrent liabilities	448	558
Total liabilities and capitalization	4,360	6,663
FG | Affiliates
CURRENT LIABILITIES:
Other Short-term Borrowings	483	389
NG
CURRENT ASSETS:
Cash and cash equivalents	0	0	0	0
Receivables-
Customers	0	0
Affiliated companies	417	461
Other Receivables	8	19
Notes receivable from affiliated companies	1,294	805
Materials and supplies, at average cost	80	213
Derivatives	0	0
Collateral	0	0
Prepayments and other	1	0
Total current assets	1,800	1,498
PROPERTY, PLANT AND EQUIPMENT:
In service	4,703	8,233
Less — Accumulated provision for depreciation	4,144	3,775
Property, plant and equipment in service net of accumulated provision for depreciation	559	4,458
Construction work in progress	358	878
Total net property, plant and equipment	917	5,336
INVESTMENTS:
Nuclear plant decommissioning trusts	1,552	1,327
Investment in affiliated companies	0	0
Other	1	0
Total other property and investments	1,553	1,327
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	883	0
Customer intangibles	0	0
Goodwill		0
Property taxes	28	28
Derivatives	0	0
Other	0	14
Total deferred charges and other assets	911	42
Total assets	5,181	8,203
CURRENT LIABILITIES:
Currently payable long-term debt	5	308
Short-term borrowings	0	0
Accounts payable-
Affiliated companies	406	368
Other	0	0
Accrued taxes	61	62
Derivatives	0	0
Other	10	9
Total current liabilities	482	747
CAPITALIZATION:
Total equity	2,006	4,476
Long-term debt and other long-term obligations	1,120	840
Total capitalization	3,126	5,316
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	0	0
Accumulated deferred income taxes	0	697
Retirement benefits	0	0
Asset retirement obligations	713	640
Derivatives	0	0
Other	860	803
Total noncurrent liabilities	1,573	2,140
Total liabilities and capitalization	5,181	8,203
NG | Affiliates
CURRENT LIABILITIES:
Other Short-term Borrowings	0	0
FES
CURRENT ASSETS:
Cash and cash equivalents	2	2	$ 2	$ 2
Receivables-
Customers	213	275
Affiliated companies	452	451
Other Receivables	27	59
Notes receivable from affiliated companies	29	11
Materials and supplies, at average cost	267	470
Derivatives	137	154
Collateral	157	70
Prepayments and other	63	66
Total current assets	1,347	1,558
PROPERTY, PLANT AND EQUIPMENT:
In service	7,057	14,311
Less — Accumulated provision for depreciation	5,929	5,765
Property, plant and equipment in service net of accumulated provision for depreciation	1,128	8,546
Construction work in progress	427	1,157
Total net property, plant and equipment	1,555	9,703
INVESTMENTS:
Nuclear plant decommissioning trusts	1,552	1,327
Investment in affiliated companies	0	0
Other	10	10
Total other property and investments	1,562	1,337
DEFERRED CHARGES AND OTHER ASSETS:
Accumulated deferred income tax benefits	2,279	0
Customer intangibles	9	61
Goodwill	0	23
Property taxes	40	40
Derivatives	77	79
Other	372	367
Total deferred charges and other assets	2,777	570
Total assets	7,241	13,168
CURRENT LIABILITIES:
Currently payable long-term debt	179	512
Short-term borrowings	0	8
Accounts payable-
Affiliated companies	550	542
Other	110	139
Accrued taxes	143	76
Derivatives	77	104
Other	156	181
Total current liabilities	1,316	1,562
CAPITALIZATION:
Total equity	218	5,605
Long-term debt and other long-term obligations	2,813	2,510
Total capitalization	3,031	8,115
NONCURRENT LIABILITIES:
Deferred gain on sale and leaseback transaction	757	791
Accumulated deferred income taxes	0	600
Retirement benefits	197	332
Asset retirement obligations	901	831
Derivatives	52	38
Other	987	899
Total noncurrent liabilities	2,894	3,491
Total liabilities and capitalization	7,241	13,168
FES | Affiliates
CURRENT LIABILITIES:
Other Short-term Borrowings	$ 101	$ 0