Consolidated Statements of Income (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Statement Of Income [Line Items]
Operating revenues	$ 8,907	$ 10,190	$ 9,885
Operating expenses
Fuel used in electric generation	2,893	3,300	3,752
Purchased power	1,093	1,279	911
Operation and maintenance	2,036	2,027	1,894
Depreciation, amortization and accretion	701	920	986
Taxes other than on income	562	580	557
Other	34	30	13
Total operating expenses	7,319	8,136	8,113
Operating income	1,588	2,054	1,772
Other income (expense)
Interest income	2	7	14
Allowance for equity funds used during construction	103	92	124
Other, net	(58)	0	6
Total other income, net	47	99	144
Interest charges
Interest charges	760	779	718
Allowance for borrowed funds used during construction	(35)	(32)	(39)
Total interest charges, net	725	747	679
Income from continuing operations before income tax	910	1,406	1,237
Income tax expense	323	539	397
Income from continuing operations	587	867	840
Discontinued operations, net of tax	(5)	(4)	(79)
Net income	582	863	761
Net income attributable to noncontrolling interests, net of tax	(7)	(7)	(4)
Net income attributable to controlling interests	575	856	757
Average common shares outstanding - basic	296	291	279
Basic and diluted earnings per common share
Income from continuing operations attributable to controlling interests, net of tax	$ 1.96	$ 2.96	$ 2.99
Discontinued operations attributable to controlling interests, net of tax	$ (0.02)	$ (0.01)	$ (0.28)
Net income attributable to controlling interests	$ 1.94	$ 2.95	$ 2.71
Dividends declared per common share	$ 2.119	$ 2.480	$ 2.480
Amounts attributable to controlling interests
Income from continuing operations, net of tax	580	860	836
Discontinued operations, net of tax	(5)	(4)	(79)
Net income attributable to controlling interests	575	856	757
PEC
Statement Of Income [Line Items]
Operating revenues	4,528	4,922	4,627
Operating expenses
Fuel used in electric generation	1,387	1,686	1,680
Purchased power	315	302	229
Operation and maintenance	1,182	1,158	1,072
Depreciation, amortization and accretion	514	479	470
Taxes other than on income	211	218	210
Other	34	8	0
Total operating expenses	3,643	3,851	3,661
Operating income	885	1,071	966
Other income (expense)
Interest income	1	3	5
Allowance for equity funds used during construction	71	64	33
Other, net	(1)	0	(18)
Total other income, net	71	67	20
Interest charges
Interest charges	205	205	207
Allowance for borrowed funds used during construction	(21)	(19)	(12)
Total interest charges, net	184	186	195
Income from continuing operations before income tax	772	952	791
Income tax expense	256	350	277
Net income	516	602	514
Net income attributable to noncontrolling interests, net of tax	0	1	2
Net income attributable to controlling interests	516	603	516
Preferred stock dividend requirement	(3)	(3)	(3)
Net income available to parent	513	600	513
Amounts attributable to controlling interests
Net income attributable to controlling interests	516	603	516
PEF
Statement Of Income [Line Items]
Operating revenues	4,369	5,254	5,251
Operating expenses
Fuel used in electric generation	1,506	1,614	2,072
Purchased power	778	977	682
Operation and maintenance	881	912	839
Depreciation, amortization and accretion	169	426	502
Taxes other than on income	350	362	347
Other	(13)	4	7
Total operating expenses	3,671	4,295	4,449
Operating income	698	959	802
Other income (expense)
Interest income	1	1	4
Allowance for equity funds used during construction	32	28	91
Other, net	2	(1)	5
Total other income, net	35	28	100
Interest charges
Interest charges	253	271	258
Allowance for borrowed funds used during construction	(14)	(13)	(27)
Total interest charges, net	239	258	231
Income from continuing operations before income tax	494	729	671
Income tax expense	180	276	209
Net income	314	453	462
Preferred stock dividend requirement	(2)	(2)	(2)
Net income available to parent	$ 312	$ 451	$ 460