Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	$ 230	$ 271	$ 246	$ 284
Other comprehensive income (loss) before reclassifications	(7)	49	7	84
Amounts reclassified from AOCI	(38)	(62)	(78)	(118)
Other comprehensive income (loss)	(45)	(13)	(71)	(34)
Income taxes (benefits) on other comprehensive income (loss)	(17)	(6)	(27)	(14)
Other comprehensive income (loss), net of tax	(28)	(7)	(44)	(20)
AOCI Ending Balance	202	264	202	264
FES
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	56	62	57	54
Other comprehensive income (loss) before reclassifications	(7)	43	6	76
Amounts reclassified from AOCI	(10)	(26)	(25)	(47)
Other comprehensive income (loss)	(17)	17	(19)	29
Income taxes (benefits) on other comprehensive income (loss)	(6)	7	(7)	11
Other comprehensive income (loss), net of tax	(11)	10	(12)	18
AOCI Ending Balance	45	72	45	72
Gains & Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	(36)	(36)	(37)	(36)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from AOCI	1	(1)	2	(1)
Other comprehensive income (loss)	1	(1)	2	(1)
Income taxes (benefits) on other comprehensive income (loss)	1	(1)	1	(1)
Other comprehensive income (loss), net of tax	0	0	1	0
AOCI Ending Balance	(36)	(36)	(36)	(36)
Gains & Losses on Cash Flow Hedges | FES
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	(8)	(2)	(7)	(1)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from AOCI	(1)	(3)	(2)	(5)
Other comprehensive income (loss)	(1)	(3)	(2)	(5)
Income taxes (benefits) on other comprehensive income (loss)	0	0	0	(1)
Other comprehensive income (loss), net of tax	(1)	(3)	(2)	(4)
AOCI Ending Balance	(9)	(5)	(9)	(5)
Unrealized Gains on AFS Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	28	22	25	9
Other comprehensive income (loss) before reclassifications	(7)	49	7	84
Amounts reclassified from AOCI	(7)	(19)	(17)	(33)
Other comprehensive income (loss)	(14)	30	(10)	51
Income taxes (benefits) on other comprehensive income (loss)	(5)	11	(4)	19
Other comprehensive income (loss), net of tax	(9)	19	(6)	32
AOCI Ending Balance	19	41	19	41
Unrealized Gains on AFS Securities | FES
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	24	20	21	8
Other comprehensive income (loss) before reclassifications	(7)	43	6	76
Amounts reclassified from AOCI	(5)	(18)	(15)	(32)
Other comprehensive income (loss)	(12)	25	(9)	44
Income taxes (benefits) on other comprehensive income (loss)	(4)	9	(4)	16
Other comprehensive income (loss), net of tax	(8)	16	(5)	28
AOCI Ending Balance	16	36	16	36
Defined Benefit Pension & OPEB Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	238	285	258	311
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from AOCI	(32)	(42)	(63)	(84)
Other comprehensive income (loss)	(32)	(42)	(63)	(84)
Income taxes (benefits) on other comprehensive income (loss)	(13)	(16)	(24)	(32)
Other comprehensive income (loss), net of tax	(19)	(26)	(39)	(52)
AOCI Ending Balance	219	259	219	259
Defined Benefit Pension & OPEB Plans | FES
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
AOCI Beginning Balance	40	44	43	47
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from AOCI	(4)	(5)	(8)	(10)
Other comprehensive income (loss)	(4)	(5)	(8)	(10)
Income taxes (benefits) on other comprehensive income (loss)	(2)	(2)	(3)	(4)
Other comprehensive income (loss), net of tax	(2)	(3)	(5)	(6)
AOCI Ending Balance	$ 38	$ 41	$ 38	$ 41