Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	$ 171	$ 246
Other comprehensive income (loss) before reclassifications	41	14
Amounts reclassified from AOCI	(29)	(40)
Other comprehensive income (loss)	12	(26)
Income taxes (benefits) on other comprehensive income (loss)	4	(10)
Other comprehensive income (loss), net of tax	8	(16)
AOCI Ending Balance	179	230
FES
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	46	57
Other comprehensive income (loss) before reclassifications	36	13
Amounts reclassified from AOCI	(17)	(15)
Other comprehensive income (loss)	19	(2)
Income taxes (benefits) on other comprehensive income (loss)	7	(1)
Other comprehensive income (loss), net of tax	12	(1)
AOCI Ending Balance	58	56
Gains & Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	(33)	(37)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from AOCI	2	1
Other comprehensive income (loss)	2	1
Income taxes (benefits) on other comprehensive income (loss)	1	0
Other comprehensive income (loss), net of tax	1	1
AOCI Ending Balance	(32)	(36)
Gains & Losses on Cash Flow Hedges | FES
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	(9)	(7)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from AOCI	0	(1)
Other comprehensive income (loss)	0	(1)
Income taxes (benefits) on other comprehensive income (loss)	0	0
Other comprehensive income (loss), net of tax	0	(1)
AOCI Ending Balance	(9)	(8)
Unrealized Gains on AFS Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	18	25
Other comprehensive income (loss) before reclassifications	41	14
Amounts reclassified from AOCI	(13)	(10)
Other comprehensive income (loss)	28	4
Income taxes (benefits) on other comprehensive income (loss)	10	1
Other comprehensive income (loss), net of tax	18	3
AOCI Ending Balance	36	28
Unrealized Gains on AFS Securities | FES
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	16	21
Other comprehensive income (loss) before reclassifications	36	13
Amounts reclassified from AOCI	(13)	(10)
Other comprehensive income (loss)	23	3
Income taxes (benefits) on other comprehensive income (loss)	9	0
Other comprehensive income (loss), net of tax	14	3
AOCI Ending Balance	30	24
Defined Benefit Pension & OPEB Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	186	258
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from AOCI	(18)	(31)
Other comprehensive income (loss)	(18)	(31)
Income taxes (benefits) on other comprehensive income (loss)	(7)	(11)
Other comprehensive income (loss), net of tax	(11)	(20)
AOCI Ending Balance	175	238
Defined Benefit Pension & OPEB Plans | FES
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	39	43
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from AOCI	(4)	(4)
Other comprehensive income (loss)	(4)	(4)
Income taxes (benefits) on other comprehensive income (loss)	(2)	(1)
Other comprehensive income (loss), net of tax	(2)	(3)
AOCI Ending Balance	$ 37	$ 40