Supplemental Guarantor Information (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities	$ (92)	$ 50
New Financing-
Long-term debt	1,467	1,800
Short-term borrowings, net	0	181
Redemptions and Repayments-
Long-term debt	(489)	(846)
Short-term borrowings, net	(319)	0
Tender premiums	0	(110)
Other	(10)	(23)
Net cash provided from (used for) financing activities	498	772
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(821)	(826)
Nuclear fuel	(55)	(27)
Proceeds from asset sales	394	0
Sales of investment securities held in trusts	621	539
Purchases of investment securities held in trusts	(646)	(565)
Other	3	(1)
Net cash used for investing activities	(515)	(927)
Net change in cash and cash equivalents	(109)	(105)
Cash and cash equivalents at beginning of period	218	172
Cash and cash equivalents at end of period	109	67
FES
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities	(450)	(529)
New Financing-
Long-term debt	0
Short-term borrowings, net	209	894
Equity contribution from parent	500
Redemptions and Repayments-
Long-term debt	0	(369)
Short-term borrowings, net	0	0
Tender premiums		(67)
Other	(1)	0
Net cash provided from (used for) financing activities	708	458
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(2)	(5)
Nuclear fuel	0	0
Proceeds from asset sales	0	0
Sales of investment securities held in trusts	0	0
Purchases of investment securities held in trusts	0	0
Loans to affiliated companies, net	(254)	75
Other	(2)	1
Net cash used for investing activities	(258)	71
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
FGCO
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities	87	298
New Financing-
Long-term debt	235
Short-term borrowings, net	72	0
Equity contribution from parent	0
Redemptions and Repayments-
Long-term debt	(248)	(107)
Short-term borrowings, net	0	(76)
Tender premiums		0
Other	(2)	(1)
Net cash provided from (used for) financing activities	57	(184)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(28)	(138)
Nuclear fuel	0	0
Proceeds from asset sales	307	17
Sales of investment securities held in trusts	0	0
Purchases of investment securities held in trusts	0	0
Loans to affiliated companies, net	(425)	7
Other	2	0
Net cash used for investing activities	(144)	(114)
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	2	3
Cash and cash equivalents at end of period	2	3
Nuclear Generation Corp
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities	51	36
New Financing-
Long-term debt	182
Short-term borrowings, net	0	586
Equity contribution from parent	0
Redemptions and Repayments-
Long-term debt	(197)	0
Short-term borrowings, net	(151)	0
Tender premiums		0
Other	(1)	0
Net cash provided from (used for) financing activities	(167)	586
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(268)	(74)
Nuclear fuel	(55)	(27)
Proceeds from asset sales	0	0
Sales of investment securities held in trusts	423	252
Purchases of investment securities held in trusts	(438)	(265)
Loans to affiliated companies, net	454	(508)
Other	0	0
Net cash used for investing activities	116	(622)
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Eliminations
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities	0	0
New Financing-
Long-term debt	0
Short-term borrowings, net	(161)	(778)
Equity contribution from parent	0
Redemptions and Repayments-
Long-term debt	0	0
Short-term borrowings, net	151	76
Tender premiums		0
Other		0
Net cash provided from (used for) financing activities	(10)	(702)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	0	0
Nuclear fuel	0	0
Proceeds from asset sales	0	0
Sales of investment securities held in trusts	0	0
Purchases of investment securities held in trusts	0	0
Loans to affiliated companies, net	10	702
Other	0	0
Net cash used for investing activities	10	702
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
FES
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities	(312)	(195)
New Financing-
Long-term debt	417	0
Short-term borrowings, net	120	702
Equity contribution from parent	500	0
Redemptions and Repayments-
Long-term debt	(445)	(476)
Short-term borrowings, net	0	0
Tender premiums	0	(67)
Other	(4)	(1)
Net cash provided from (used for) financing activities	588	158
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(298)	(217)
Nuclear fuel	(55)	(27)
Proceeds from asset sales	307	17
Sales of investment securities held in trusts	423	252
Purchases of investment securities held in trusts	(438)	(265)
Loans to affiliated companies, net	(215)	276
Other	0	1
Net cash used for investing activities	(276)	37
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	2	3
Cash and cash equivalents at end of period	$ 2	$ 3