Supplemental Guarantor Information (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Cash Flows [Abstract]
NET CASH PROVIDED FROM (USED FOR) OPERATING ACTIVITIES	$ 3,808	$ 3,383	$ 3,460
New Financing-
Long-term debt	4,675	1,976	1,311
Short-term borrowings, net	0	975	0
Redemptions and Repayments-
Long-term debt	(2,291)	(2,331)	(879)
Short-term borrowings, net	(2,375)	0	(91)
Common stock dividend payments	(639)	(611)	(607)
Other	(72)	(43)	(26)
Net cash used for financing activities	(702)	(34)	(292)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(2,587)	(2,835)	(2,704)
Nuclear fuel	(254)	(232)	(190)
Proceeds from asset sales	388	15	20
Sales of investment securities held in trusts	2,170	1,678	1,534
Purchases of investment securities held in trusts	(2,268)	(1,789)	(1,648)
Other	7	27	8
Net cash used for investing activities	(2,716)	(3,281)	(3,122)
Net change in cash and cash equivalents	390	68	46
Cash and cash equivalents at beginning of period	199	131	85
Cash and cash equivalents at end of period	589	199	131
Eliminations
Consolidated Statements of Cash Flows [Abstract]
NET CASH PROVIDED FROM (USED FOR) OPERATING ACTIVITIES	(26)	(25)	(24)
New Financing-
Long-term debt		0	0
Short-term borrowings, net	(271)	(941)	(863)
Redemptions and Repayments-
Long-term debt	26	25	24
Short-term borrowings, net			(98)
Common stock dividend payments			0
Other	0	0	0
Net cash used for financing activities	(245)	(916)	(937)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	0	0	0
Nuclear fuel	0	0	0
Proceeds from asset sales		0	0
Sales of investment securities held in trusts	0	0	0
Purchases of investment securities held in trusts	0	0	0
Cash investments	0	0	0
Loans to affiliated companies, net	271	941	961
Other		0	0
Net cash used for investing activities	271	941	961
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
FES
Consolidated Statements of Cash Flows [Abstract]
NET CASH PROVIDED FROM (USED FOR) OPERATING ACTIVITIES	(485)	(842)	(637)
New Financing-
Long-term debt		0	0
Short-term borrowings, net	356	948	796
Redemptions and Repayments-
Long-term debt	0	0	(17)
Short-term borrowings, net			0
Common stock dividend payments			(70)
Other	(1)	0	0
Net cash used for financing activities	355	948	709
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(2)	(30)	(5)
Nuclear fuel	0	0	0
Proceeds from asset sales		9	10
Sales of investment securities held in trusts	0	0	0
Purchases of investment securities held in trusts	0	0	0
Cash investments	(3)	10	(10)
Loans to affiliated companies, net	135	(95)	(67)
Other		0	0
Net cash used for investing activities	130	(106)	(72)
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
FG
Consolidated Statements of Cash Flows [Abstract]
NET CASH PROVIDED FROM (USED FOR) OPERATING ACTIVITIES	516	550	552
New Financing-
Long-term debt		186	45
Short-term borrowings, net	(81)	94	67
Redemptions and Repayments-
Long-term debt	(184)	(224)	(70)
Short-term borrowings, net			0
Common stock dividend payments			0
Other	(6)	(7)	(6)
Net cash used for financing activities	(271)	49	36
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(88)	(224)	(223)
Nuclear fuel	0	0	0
Proceeds from asset sales		0	3
Sales of investment securities held in trusts	0	0	0
Purchases of investment securities held in trusts	0	0	0
Cash investments	0	0	0
Loans to affiliated companies, net	(158)	(376)	(372)
Other		1	4
Net cash used for investing activities	(246)	(599)	(588)
Net change in cash and cash equivalents	(1)	0	0
Cash and cash equivalents at beginning of period	2	2	2
Cash and cash equivalents at end of period	1	2	2
NG
Consolidated Statements of Cash Flows [Abstract]
NET CASH PROVIDED FROM (USED FOR) OPERATING ACTIVITIES	722	1,103	1,261
New Financing-
Long-term debt		285	296
Short-term borrowings, net	0	0	0
Redemptions and Repayments-
Long-term debt	(5)	(308)	(348)
Short-term borrowings, net			(28)
Common stock dividend payments			0
Other	0	(2)	(1)
Net cash used for financing activities	(5)	(25)	(81)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(185)	(292)	(399)
Nuclear fuel	(254)	(232)	(190)
Proceeds from asset sales		0	0
Sales of investment securities held in trusts	940	717	733
Purchases of investment securities held in trusts	(999)	(783)	(791)
Cash investments	0	0	0
Loans to affiliated companies, net	(219)	(488)	(533)
Other		0	0
Net cash used for investing activities	(717)	(1,078)	(1,180)
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
Consolidated
Consolidated Statements of Cash Flows [Abstract]
NET CASH PROVIDED FROM (USED FOR) OPERATING ACTIVITIES	727	786	1,152
New Financing-
Long-term debt	0	471	341
Short-term borrowings, net	4	101	0
Redemptions and Repayments-
Long-term debt	(163)	(507)	(411)
Short-term borrowings, net	0	0	(126)
Common stock dividend payments	0	0	(70)
Other	(7)	(9)	(7)
Net cash used for financing activities	(166)	56	(273)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(275)	(546)	(627)
Nuclear fuel	(254)	(232)	(190)
Proceeds from asset sales	0	9	13
Sales of investment securities held in trusts	940	717	733
Purchases of investment securities held in trusts	(999)	(783)	(791)
Cash investments	(3)	10	(10)
Loans to affiliated companies, net	29	(18)	(11)
Other	0	1	4
Net cash used for investing activities	(562)	(842)	(879)
Net change in cash and cash equivalents	(1)	0	0
Cash and cash equivalents at beginning of period	2	2	2
Cash and cash equivalents at end of period	$ 1	$ 2	$ 2