Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI Beginning Balance	$ 246	$ 284	$ 385
Other comprehensive income before reclassifications	24	181	81
Amounts reclassified from AOCI	(146)	(233)	(248)
Other comprehensive loss	(122)	(52)	(167)
Income tax benefits on other comprehensive loss	(47)	(14)	(66)
Other comprehensive loss, net of tax	(75)	(38)	(101)
AOCI Ending Balance	171	246	284
FES
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI Beginning Balance	57	54	72
Other comprehensive income before reclassifications	25	93	46
Amounts reclassified from AOCI	(43)	(88)	(75)
Other comprehensive loss	(18)	5	(29)
Income tax benefits on other comprehensive loss	(7)	2	(11)
Other comprehensive loss, net of tax	(11)	3	(18)
AOCI Ending Balance	46	57	54
Gains & Losses on Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI Beginning Balance	(37)	(36)	(38)
Other comprehensive income before reclassifications	0	0	0
Amounts reclassified from AOCI	5	(2)	3
Other comprehensive loss	5	(2)	3
Income tax benefits on other comprehensive loss	1	(1)	1
Other comprehensive loss, net of tax	4	(1)	2
AOCI Ending Balance	(33)	(37)	(36)
Gains & Losses on Cash Flow Hedges | FES
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI Beginning Balance	(7)	(1)	3
Other comprehensive income before reclassifications	0	0	0
Amounts reclassified from AOCI	(3)	(10)	(6)
Other comprehensive loss	(3)	(10)	(6)
Income tax benefits on other comprehensive loss	(1)	(4)	(2)
Other comprehensive loss, net of tax	(2)	(6)	(4)
AOCI Ending Balance	(9)	(7)	(1)
Unrealized Gains on AFS Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI Beginning Balance	25	9	15
Other comprehensive income before reclassifications	14	89	46
Amounts reclassified from AOCI	(25)	(63)	(56)
Other comprehensive loss	(11)	26	(10)
Income tax benefits on other comprehensive loss	(4)	10	(4)
Other comprehensive loss, net of tax	(7)	16	(6)
AOCI Ending Balance	18	25	9
Unrealized Gains on AFS Securities | FES
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI Beginning Balance	21	8	13
Other comprehensive income before reclassifications	15	80	41
Amounts reclassified from AOCI	(24)	(59)	(49)
Other comprehensive loss	(9)	21	(8)
Income tax benefits on other comprehensive loss	(4)	8	(3)
Other comprehensive loss, net of tax	(5)	13	(5)
AOCI Ending Balance	16	21	8
Defined Benefit Pension & OPEB Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI Beginning Balance	258	311	408
Other comprehensive income before reclassifications	10	92	35
Amounts reclassified from AOCI	(126)	(168)	(195)
Other comprehensive loss	(116)	(76)	(160)
Income tax benefits on other comprehensive loss	(44)	(23)	(63)
Other comprehensive loss, net of tax	(72)	(53)	(97)
AOCI Ending Balance	186	258	311
Defined Benefit Pension & OPEB Plans | FES
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI Beginning Balance	43	47	56
Other comprehensive income before reclassifications	10	13	5
Amounts reclassified from AOCI	(16)	(19)	(20)
Other comprehensive loss	(6)	(6)	(15)
Income tax benefits on other comprehensive loss	(2)	(2)	(6)
Other comprehensive loss, net of tax	(4)	(4)	(9)
AOCI Ending Balance	$ 39	$ 43	$ 47