Accumulated Other Comprehensive Income (Details 1) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Other operating expenses	$ (1,023)	$ (953)	$ (964)	$ (918)	$ (950)	$ (842)	$ (900)	$ (1,057)	$ (3,858)	$ (3,749)	$ (3,962)
Interest expense - other									(1,157)	(1,132)	(1,081)
Total before taxes									(9,232)	893	171
Income taxes (benefits)	3,389	(251)	130	(213)	170	(226)	(115)	(144)	3,055	(315)	42
NET INCOME (LOSS)	(5,796)	380	(1,089)	328	(226)	395	187	222	(6,177)	578	299
FES
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Other operating expenses	(352)	(316)	(369)	(240)	(312)	(246)	(337)	(413)	(1,277)	(1,308)	(1,635)
Total before taxes									(8,443)	147	(588)
Income taxes (benefits)	2,983	(56)	143	(82)	(1)	(70)	4	2	2,988	(65)	228
NET INCOME (LOSS)	$ (5,188)	$ 40	$ (438)	$ 131	$ (14)	$ 120	$ (21)	$ (3)	(5,455)	82	(244)
Reclassifications from AOCI | Gains & losses on cash flow hedges
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total before taxes									8	5	(2)
Income taxes (benefits)									(3)	(1)	1
NET INCOME (LOSS)									5	4	(1)
Reclassifications from AOCI | Gains & losses on cash flow hedges | FES
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Income taxes (benefits)									0	1	4
NET INCOME (LOSS)									0	(2)	(6)
Reclassifications from AOCI | Gains & losses on cash flow hedges | Commodity contracts
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Other operating expenses									0	(3)	(10)
Reclassifications from AOCI | Gains & losses on cash flow hedges | Commodity contracts | FES
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Other operating expenses									0	(3)	(10)
Reclassifications from AOCI | Gains & losses on cash flow hedges | Long-term debt
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Interest expense - other									8	8	8
Reclassifications from AOCI | Unrealized gains on AFS securities
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Investment income									(51)	(25)	(63)
Income taxes (benefits)									19	9	24
NET INCOME (LOSS)									(32)	(16)	(39)
Reclassifications from AOCI | Unrealized gains on AFS securities | FES
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Investment income									(48)	(24)	(59)
Income taxes (benefits)									18	9	22
NET INCOME (LOSS)									(30)	(15)	(37)
Reclassifications from AOCI | Defined benefit pension and OPEB plans
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Prior-service costs									(72)	(126)	(168)
Income taxes (benefits)									27	49	65
NET INCOME (LOSS)									(45)	(77)	(103)
Reclassifications from AOCI | Defined benefit pension and OPEB plans | FES
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Prior-service costs									(14)	(16)	(19)
Income taxes (benefits)									5	6	7
NET INCOME (LOSS)									$ (9)	$ (10)	$ (12)