Supplemental Guarantor Information (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities			$ 493	$ 62
New Financing-
Long-term debt			2,245	182
Short-term borrowings, net			1,285	1,890
Redemptions and Repayments-
Long-term debt			(1,968)	(746)
Tender premiums			(110)	0
Other			(16)	(35)
Net cash provided from (used for) financing activities			976	831
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions	(586)	(394)	(1,412)	(911)
Nuclear fuel			(50)	(90)
Sales of investment securities held in trusts			1,177	382
Purchases of investment securities held in trusts			(1,173)	(420)
Other			2	(13)
Net cash used for investing activities			(1,570)	(1,001)
Net change in cash and cash equivalents			(101)	(108)
Cash and cash equivalents at beginning of period			172	202
Cash and cash equivalents at end of period	71	94	71	94
FES
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities			(687)	(525)
New Financing-
Long-term debt				0
Short-term borrowings, net			240	532
Equity contribution from parent			1,500
Redemptions and Repayments-
Long-term debt			(770)	0
Short-term borrowings, net				0
Tender premiums			(67)
Other			(2)	(1)
Net cash provided from (used for) financing activities			901	531
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions			(7)	(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			(207)	1
Customer acquisition costs			0
Other			0	(2)
Net cash used for investing activities			(214)	(6)
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	0	0
FGCO
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities			390	308
New Financing-
Long-term debt				52
Short-term borrowings, net			112	46
Equity contribution from parent			0
Redemptions and Repayments-
Long-term debt			(352)	(63)
Short-term borrowings, net				0
Tender premiums			0
Other			(3)	(4)
Net cash provided from (used for) financing activities			(243)	31
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions			(163)	(44)
Nuclear fuel			0	0
Proceeds from asset sales			19	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)	(308)
Customer acquisition costs			0
Other			3	(4)
Net cash used for investing activities			(148)	(339)
Net change in cash and cash equivalents			(1)	0
Cash and cash equivalents at beginning of period			3	7
Cash and cash equivalents at end of period	2	7	2	7
Nuclear Generation Corp
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities			308	446
New Financing-
Long-term debt				30
Short-term borrowings, net			0	0
Equity contribution from parent			0
Redemptions and Repayments-
Long-term debt			(68)	(87)
Short-term borrowings, net				(32)
Tender premiums			0
Other				(1)
Net cash provided from (used for) financing activities			(68)	(90)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions			(180)	(164)
Nuclear fuel			(50)	(90)
Proceeds from asset sales			0	0
Sales of investment securities held in trusts			487	109
Purchases of investment securities held in trusts			(515)	(127)
Loans to affiliated companies, net			18	(84)
Customer acquisition costs			0
Other			0	0
Net cash used for investing activities			(240)	(356)
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	0	0
Eliminations
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities			(11)	(10)
New Financing-
Long-term debt				0
Short-term borrowings, net			(352)	(578)
Equity contribution from parent			0
Redemptions and Repayments-
Long-term debt			11	10
Short-term borrowings, net				32
Tender premiums			0
Other				0
Net cash provided from (used for) financing activities			(341)	(536)
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			352	546
Customer acquisition costs			0
Other			0	0
Net cash used for investing activities			352	546
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	0	0
FES
Consolidated Statements of Cash Flows [Abstract]
Net cash provided from operating activities			0	219
New Financing-
Long-term debt			0	82
Short-term borrowings, net			0	0
Equity contribution from parent	1,500		1,500	0
Redemptions and Repayments-
Long-term debt			(1,179)	(140)
Short-term borrowings, net				0
Tender premiums			(67)	0
Other			(5)	(6)
Net cash provided from (used for) financing activities			249	(64)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property additions			(350)	(213)
Nuclear fuel			(50)	(90)
Proceeds from asset sales			19	17
Sales of investment securities held in trusts			487	109
Purchases of investment securities held in trusts			(515)	(127)
Loans to affiliated companies, net			156	155
Customer acquisition costs			0
Other			3	(6)
Net cash used for investing activities			(250)	(155)
Net change in cash and cash equivalents			(1)	0
Cash and cash equivalents at beginning of period			3	7
Cash and cash equivalents at end of period	$ 2	$ 7	$ 2	$ 7