Conosolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating activities
Net income	$ 582	$ 863	$ 761
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation, amortization and accretion	870	1,083	1,135
Deferred income taxes and investment tax credits, net	353	478	220
Deferred fuel cost (credit)	(102)	(2)	290
Allowance for equity funds used during construction	(103)	(92)	(124)
Amount to be refunded to customers (Note 8C)	288	0	0
Pension, postretirement and other employee benefits	180	198	135
Other adjustments to net income	50	49	136
Cash provided (used) by changes in operating assets and liabilities
Receivables	175	(200)	26
Inventory	(210)	98	(99)
Derivative collateral posted	20	(23)	200
Other assets	(23)	(1)	14
Income taxes, net	51	90	(14)
Accounts payable	(69)	125	(26)
Accrued pension and other benefits	(396)	(164)	(285)
Other liabilities	(51)	35	(98)
Net cash provided (used) by operating activities	1,615	2,537	2,271
Investing activities
Gross property additions	(2,066)	(2,221)	(2,295)
Nuclear fuel additions	(226)	(221)	(200)
Purchases of available-for-sale securities and other investments	(5,017)	(7,009)	(2,350)
Proceeds from available-for-sale securities and other investments	4,970	6,990	2,314
Insurance proceeds	79	64	0
Other investing activities	48	(3)	(1)
Net cash provided (used) by investing activities	(2,212)	(2,400)	(2,532)
Financing activities
Issuance of common stock, net	53	434	623
Dividends paid on common stock	(734)	(717)	(693)
Payments of short-term debt with original maturities greater than 90 days	0	0	(629)
Net increase (decrease) in short-term debt	667	(140)	(381)
Proceeds from issuance of long-term debt, net	1,286	591	2,278
Retirement of long-term debt	(1,000)	(400)	(400)
Other financing activities	(56)	(19)	8
Net cash provided (used) by financing activities	216	(251)	806
Net increase (decrease) in cash and cash equivalents	(381)	(114)	545
Cash and cash equivalents at beginning of period	611	725	180
Cash and cash equivalents at end of period	230	611	725
Supplemental disclosures
Cash paid for interest less amount capitalized, net	793	709	701
Cash (received) paid for income taxes	(78)	(56)	87
Significant noncash transactions
Accrued property additions	334	313	252
Asset retirement obligation additions and estimate revisions	(4)	(36)	(384)
PEC
Operating activities
Net income	516	602	514
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation, amortization and accretion	659	602	585
Deferred income taxes and investment tax credits, net	262	285	64
Deferred fuel cost (credit)	43	79	187
Allowance for equity funds used during construction	(71)	(64)	(33)
Pension, postretirement and other employee benefits	67	78	65
Other adjustments to net income	(50)	4	67
Cash provided (used) by changes in operating assets and liabilities
Receivables	106	(76)	42
Receivables from affiliated companies	31	(11)	(4)
Inventory	(184)	85	(56)
Other assets	(16)	(24)	28
Income taxes, net	92	(54)	50
Accounts payable	(26)	51	(18)
Payables to affiliated companies	(68)	37	(10)
Accrued pension and other benefits	(247)	(95)	(181)
Other liabilities	23	19	(17)
Net cash provided (used) by operating activities	1,137	1,518	1,283
Investing activities
Gross property additions	(1,232)	(1,198)	(839)
Nuclear fuel additions	(211)	(183)	(122)
Purchases of available-for-sale securities and other investments	(571)	(489)	(696)
Proceeds from available-for-sale securities and other investments	515	437	642
Changes in advances to affiliated companies	2	202	(149)
Other investing activities	28	1	1
Net cash provided (used) by investing activities	(1,469)	(1,230)	(1,163)
Financing activities
Dividends paid on preferred stock	(3)	(3)	(3)
Dividends paid to parent	(585)	(100)	(200)
Net increase (decrease) in short-term debt	185	0	(110)
Proceeds from issuance of long-term debt, net	495	0	595
Retirement of long-term debt	0	0	(400)
Changes in advances from affiliated companies	31	0	0
Contributions from parent	0	14	15
Other financing activities	(1)	(4)	0
Net cash provided (used) by financing activities	122	(93)	(103)
Net increase (decrease) in cash and cash equivalents	(210)	195	17
Cash and cash equivalents at beginning of period	230	35	18
Cash and cash equivalents at end of period	20	230	35
Supplemental disclosures
Cash paid for interest less amount capitalized, net	199	166	171
Cash (received) paid for income taxes	(97)	108	144
Significant noncash transactions
Accrued property additions	236	198	91
Asset retirement obligation additions and estimate revisions	(4)	1	(386)
PEF
Operating activities
Net income	314	453	462
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation, amortization and accretion	174	446	527
Deferred income taxes and investment tax credits, net	234	324	64
Deferred fuel cost (credit)	(145)	(81)	103
Allowance for equity funds used during construction	(32)	(28)	(91)
Amount to be refunded to customers (Note 8C)	288	0	0
Pension, postretirement and other employee benefits	62	79	28
Other adjustments to net income	26	44	88
Cash provided (used) by changes in operating assets and liabilities
Receivables	78	(110)	(15)
Receivables from affiliated companies	(8)	(3)	7
Inventory	(26)	13	(43)
Derivative collateral posted	19	(6)	190
Other assets	(4)	(17)	15
Income taxes, net	51	50	(75)
Accounts payable	(46)	79	(11)
Payables to affiliated companies	(35)	(2)	7
Accrued pension and other benefits	(137)	(61)	(83)
Other liabilities	(48)	24	(36)
Net cash provided (used) by operating activities	765	1,204	1,137
Investing activities
Gross property additions	(816)	(1,014)	(1,449)
Nuclear fuel additions	(15)	(38)	(78)
Purchases of available-for-sale securities and other investments	(4,435)	(6,386)	(1,540)
Proceeds from available-for-sale securities and other investments	4,438	6,390	1,545
Insurance proceeds	76	64	0
Other investing activities	45	(3)	(6)
Net cash provided (used) by investing activities	(707)	(987)	(1,528)
Financing activities
Dividends paid on preferred stock	(2)	(2)	(2)
Dividends paid to parent	(510)	(50)	0
Net increase (decrease) in short-term debt	233	0	(371)
Proceeds from issuance of long-term debt, net	296	591	0
Retirement of long-term debt	(300)	(300)	0
Changes in advances from affiliated companies	(1)	(212)	149
Contributions from parent	0	0	620
Other financing activities	(7)	(12)	(7)
Net cash provided (used) by financing activities	(291)	15	389
Net increase (decrease) in cash and cash equivalents	(233)	232	(2)
Cash and cash equivalents at beginning of period	249	17	19
Cash and cash equivalents at end of period	16	249	17
Supplemental disclosures
Cash paid for interest less amount capitalized, net	287	241	228
Cash (received) paid for income taxes	(83)	(98)	184
Significant noncash transactions
Accrued property additions	$ 93	$ 111	$ 156