Supplemental Guarantor Information (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities	$ 50	$ (413)
New Financing-
Short-term borrowings, net	181	1,075
Redemptions and Repayments-
Long-term debt	(956)	(16)
Other	(23)	(10)
Net cash provided from (used for) financing activities	772	819
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(826)	(517)
Nuclear fuel	(27)	(72)
Sales of investment securities held in trusts	539	251
Purchases of investment securities held in trusts	(565)	(266)
Other	(54)	(8)
Net cash used for investing activities	(927)	(534)
Net change in cash and cash equivalents	(105)	(128)
Cash and cash equivalents at beginning of period	172	202
Cash and cash equivalents at end of period	67	74
FES
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities	(529)	(419)
New Financing-
Short-term borrowings, net	894	347
Redemptions and Repayments-
Long-term debt	(436)
Short-term borrowings, net	0	0
Other		0
Net cash provided from (used for) financing activities	458	347
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(5)	(2)
Nuclear fuel	0	0
Proceeds from asset sales	0
Sales of investment securities held in trusts	0	0
Purchases of investment securities held in trusts	0	0
Loans to affiliated companies, net	75	74
Other	1	0
Net cash used for investing activities	71	72
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	298	66
New Financing-
Short-term borrowings, net	0	0
Redemptions and Repayments-
Long-term debt	(107)
Short-term borrowings, net	(76)	(20)
Other	(1)	(2)
Net cash provided from (used for) financing activities	(184)	(22)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(138)	(18)
Nuclear fuel	0	0
Proceeds from asset sales	17
Sales of investment securities held in trusts	0	0
Purchases of investment securities held in trusts	0	0
Loans to affiliated companies, net	7	(23)
Other	0	(3)
Net cash used for investing activities	(114)	(44)
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	3	7
Cash and cash equivalents at end of period	3	7
Nuclear Generation Corp
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities	36	175
New Financing-
Short-term borrowings, net	586	0
Redemptions and Repayments-
Long-term debt	0
Short-term borrowings, net	0	(32)
Other		(1)
Net cash provided from (used for) financing activities	586	(33)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(74)	(89)
Nuclear fuel	(27)	(72)
Proceeds from asset sales	0
Sales of investment securities held in trusts	252	83
Purchases of investment securities held in trusts	(265)	(90)
Loans to affiliated companies, net	(508)	25
Other	0	1
Net cash used for investing activities	(622)	(142)
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-
Short-term borrowings, net	(778)	(347)
Redemptions and Repayments-
Long-term debt	0
Short-term borrowings, net	76	52
Other		0
Net cash provided from (used for) financing activities	(702)	(295)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	0	0
Nuclear fuel	0	0
Proceeds from asset sales	0
Sales of investment securities held in trusts	0	0
Purchases of investment securities held in trusts	0	0
Loans to affiliated companies, net	702	295
Other	0	0
Net cash used for investing activities	702	295
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	(195)	(178)
New Financing-
Short-term borrowings, net	702	0
Redemptions and Repayments-
Long-term debt	(543)	0
Short-term borrowings, net	0	0
Other	(1)	(3)
Net cash provided from (used for) financing activities	158	(3)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(217)	(109)
Nuclear fuel	(27)	(72)
Proceeds from asset sales	17	0
Sales of investment securities held in trusts	252	83
Purchases of investment securities held in trusts	(265)	(90)
Loans to affiliated companies, net	276	371
Other	1	(2)
Net cash used for investing activities	37	181
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	3	7
Cash and cash equivalents at end of period	$ 3	$ 7