Condensed Consolidating Statements (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010	Dec. 31, 2009
Operating revenues
Operating revenues	$ 2,747	$ 2,962	$ 7,170	$ 7,869
Affiliate revenues	0	0	0	0
Total revenues	2,747	2,962	7,170	7,869
Operating expenses
Fuel used in electric generation	844	935	2,236	2,574
Purchased power	349	418	898	996
Operation and maintenance	487	474	1,491	1,459
Depreciation, amortization and accretion	175	201	508	680
Taxes other than on income	163	161	437	448
Other	39	20	31	25
Total operating expenses	2,057	2,209	5,601	6,182
Operating (loss) income	690	753	1,569	1,687
Other income (expense)
Interest income	1	3	2	6
Allowance for equity funds used during construction	22	22	77	68
Other, net	(70)	(5)	(60)	(5)
Total other income (expense), net	(47)	20	19	69
Interest charges
Interest charges	180	197	568	587
Allowance for borrowed funds used during construction	(8)	(8)	(26)	(24)
Total interest charges, net	172	189	542	563
(Loss) income from continuing operations before income tax and equity in earnings of consolidated subsidiaries	471	584	1,046	1,193
Income tax (benefit) expense	178	219	386	456
Equity in earnings of consolidated subsidiaries	0	0	0	0
Income from continuing operations before cumulative effect of change in accounting principle	293	365	660	737
Discontinued operations, net of tax	0	(2)	(4)	(2)
Cumulative effect of change in accounting principle, net of tax	0	2	0	0
Net income (loss)	293	365	656	735
Net (income) loss attributable to noncontrolling interests, net of tax	(2)	(4)	(5)	(4)
Net income attributable to controlling interests	291	361	651	731
ASSETS
Utility plant, net	22,015		22,015		21,240
Current assets
Cash and cash equivalents	103	691	103	691
Receivables, net	1,207		1,207		1,033
Notes receivable from affiliated companies	0		0		0
Regulatory assets	180		180		176
Derivative collateral posted	112		112		164
Prepayments and other current assets	1,823		1,823		1,492
Total current assets	3,425		3,425		3,476
Deferred debits and other assets
Investment in consolidated subsidiaries	0		0		0
Regulatory assets	2,333		2,333		2,374
Goodwill	3,655		3,655		3,655
Nuclear decommissioning trust funds	1,512		1,512		1,571
Other assets and deferred debits	737		737		738
Total deferred debits and other assets	8,237		8,237		8,338
Total assets	33,677		33,677		33,054
Equity
Common stock equity	10,112		10,112		10,023
Noncontrolling interests	3		3		4
Cumulative effect of change in accounting principle	10,115	10,024	10,115	10,024	10,027	9,455
Preferred stock of subsidiaries	93		93		93
Long-term debt, affiliate	273		273		273
Long-term debt, net	11,717		11,717		11,864
Total capitalization	22,198		22,198		22,257
Current liabilities
Current portion of long-term debt	950		950		505
Short-term debt	45		45		0
Notes payable to affiliated companies	0		0		0
Derivative liabilities	303		303		259
Other current liabilities	2,250		2,250		2,191
Total current liabilities	3,548		3,548		2,955
Deferred credits and other liabilities
Noncurrent income tax liabilities	2,310		2,310		1,696
Regulatory liabilities	2,326		2,326		2,635
Other liabilities and deferred credits	3,295		3,295		3,511
Total deferred credits and other liabilities	7,931		7,931		7,842
Total capitalization and liabilities	33,677		33,677		33,054
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			1,304	1,904
Investing activities
Gross property additions			(1,535)	(1,643)
Nuclear fuel additions			(134)	(164)
Proceeds from sales of assets to affiliated companies				0
Purchases of available-for-sale securities and other investments			(4,536)	(5,927)
Proceeds from available-for-sale securities and other investments			4,509	5,915
Changes in advances to affiliated companies			0	0
Return of investment in consolidated subsidiaries			0	0
Contributions to consolidated subsidiaries			0	0
Other investing activities			121	15
Net cash provided (used) by investing activities			(1,575)	(1,804)
Financing activities
Issuance of common stock, net			42	419
Dividends paid on common stock			(550)	(535)
Dividends paid to parent			0	0
Dividends paid to parent in excess of retained earnings			0	0
Net increase (decrease) in short-term debt			45	(140)
Proceeds from issuance of long-term debt, net			1,286	591
Retirement of long-term debt			(1,000)	(400)
Changes in advances from affiliated companies			0	0
Contributions from parent			0	0
Other financing activities			(60)	(69)
Net cash provided (used) by financing activities			(237)	(134)
Net increase (decrease) in cash and cash equivalents			(508)	(34)
Cash and cash equivalents at beginning of period			611	725
Cash and cash equivalents at end of period	103	691	103	691
Parent
Operating revenues
Operating revenues	0	0	0	0
Affiliate revenues	0	0	0	0
Total revenues	0	0	0	0
Operating expenses
Fuel used in electric generation	0	0	0	0
Purchased power	0	0	0	0
Operation and maintenance	2	2	6	5
Depreciation, amortization and accretion	0	0	0	0
Taxes other than on income	0	0	0	0
Other	0	0	0	0
Total operating expenses	2	2	6	5
Operating (loss) income	(2)	(2)	(6)	(5)
Other income (expense)
Interest income	0	2	0	6
Allowance for equity funds used during construction	0	0	0	0
Other, net	(63)	0	(59)	(1)
Total other income (expense), net	(63)	2	(59)	5
Interest charges
Interest charges	80	71	216	214
Allowance for borrowed funds used during construction	0	0	0	0
Total interest charges, net	80	71	216	214
(Loss) income from continuing operations before income tax and equity in earnings of consolidated subsidiaries	(145)	(71)	(281)	(214)
Income tax (benefit) expense	(45)	(25)	(100)	(83)
Equity in earnings of consolidated subsidiaries	391	406	832	861
Income from continuing operations before cumulative effect of change in accounting principle	291	360	651	730
Discontinued operations, net of tax	0	1	0	1
Cumulative effect of change in accounting principle, net of tax		0	0
Net income (loss)	291	361	651	731
Net (income) loss attributable to noncontrolling interests, net of tax	0	0	0	0
Net income attributable to controlling interests	291	361	651	731
ASSETS
Utility plant, net	0		0		0
Current assets
Cash and cash equivalents	0	247	0	247
Receivables, net	0		0		0
Notes receivable from affiliated companies	97		97		14
Regulatory assets	0		0		0
Derivative collateral posted	0		0		0
Income taxes receivable	0		0		0
Prepayments and other current assets	131		131		30
Total current assets	228		228		154
Deferred debits and other assets
Investment in consolidated subsidiaries	14,196		14,196		14,316
Regulatory assets	0		0		0
Goodwill	0		0		0
Nuclear decommissioning trust funds	0		0		0
Other assets and deferred debits	94		94		75
Total deferred debits and other assets	14,290		14,290		14,391
Total assets	14,518		14,518		14,545
Equity
Common stock equity	10,112		10,112		10,023
Noncontrolling interests	0		0		0
Cumulative effect of change in accounting principle	10,112		10,112		10,023
Preferred stock of subsidiaries	0		0		0
Long-term debt, affiliate	0		0		0
Long-term debt, net	3,542		3,542		3,989
Total capitalization	13,654		13,654		14,012
Current liabilities
Current portion of long-term debt	450		450		205
Short-term debt	45		45		0
Notes payable to affiliated companies	0		0		0
Derivative liabilities	35		35		18
Other current liabilities	318		318		278
Total current liabilities	848		848		501
Deferred credits and other liabilities
Noncurrent income tax liabilities	0		0		3
Regulatory liabilities	0		0		0
Other liabilities and deferred credits	16		16		29
Total deferred credits and other liabilities	16		16		32
Total capitalization and liabilities	14,518		14,518		14,545
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			659	23
Investing activities
Gross property additions			0	0
Nuclear fuel additions			0	0
Proceeds from sales of assets to affiliated companies				0
Purchases of available-for-sale securities and other investments			0	0
Proceeds from available-for-sale securities and other investments			0	0
Changes in advances to affiliated companies			(83)	(24)
Return of investment in consolidated subsidiaries			0	54
Contributions to consolidated subsidiaries			(11)	(56)
Other investing activities			(6)	0
Net cash provided (used) by investing activities			(100)	(26)
Financing activities
Issuance of common stock, net			42	419
Dividends paid on common stock			(550)	(535)
Dividends paid to parent			0	0
Dividends paid to parent in excess of retained earnings			0	0
Payments of short-term debt with original maturities greater than 90 days				0
Net increase (decrease) in short-term debt			45	(140)
Proceeds from issuance of long-term debt, net			494	0
Retirement of long-term debt			(700)	(100)
Changes in advances from affiliated companies			0	0
Contributions from parent			0	0
Other financing activities			0	0
Net cash provided (used) by financing activities			(669)	(356)
Net increase (decrease) in cash and cash equivalents			(110)	(359)
Cash and cash equivalents at beginning of period			110	606
Cash and cash equivalents at end of period	0	247	0	247
Subsidiary Guarantor
Operating revenues
Operating revenues	1,415	1,548	3,645	4,075
Affiliate revenues	0	0	0	0
Total revenues	1,415	1,548	3,645	4,075
Operating expenses
Fuel used in electric generation	456	471	1,159	1,252
Purchased power	232	309	641	761
Operation and maintenance	221	234	655	647
Depreciation, amortization and accretion	39	77	112	311
Taxes other than on income	106	102	274	278
Other	1	10	(7)	15
Total operating expenses	1,055	1,203	2,834	3,264
Operating (loss) income	360	345	811	811
Other income (expense)
Interest income	0	1	1	1
Allowance for equity funds used during construction	7	5	24	23
Other, net	(1)	(3)	5	0
Total other income (expense), net	6	3	30	24
Interest charges
Interest charges	56	74	204	219
Allowance for borrowed funds used during construction	(4)	(3)	(11)	(10)
Total interest charges, net	52	71	193	209
(Loss) income from continuing operations before income tax and equity in earnings of consolidated subsidiaries	314	277	648	626
Income tax (benefit) expense	116	99	240	235
Equity in earnings of consolidated subsidiaries	0	0	0	0
Income from continuing operations before cumulative effect of change in accounting principle	198	178	408	391
Discontinued operations, net of tax	1	(1)	(2)	0
Cumulative effect of change in accounting principle, net of tax		0	0
Net income (loss)	199	177	406	391
Net (income) loss attributable to noncontrolling interests, net of tax	(1)	(1)	(3)	(3)
Net income attributable to controlling interests	198	176	403	388
ASSETS
Utility plant, net	10,351		10,351		10,189
Current assets
Cash and cash equivalents	34	151	34	151
Receivables, net	630		630		497
Notes receivable from affiliated companies	27		27		48
Regulatory assets	128		128		105
Derivative collateral posted	98		98		140
Income taxes receivable	0		0		0
Prepayments and other current assets	816		816		751
Total current assets	1,733		1,733		1,811
Deferred debits and other assets
Investment in consolidated subsidiaries	0		0		0
Regulatory assets	1,305		1,305		1,387
Goodwill	0		0		0
Nuclear decommissioning trust funds	520		520		554
Other assets and deferred debits	215		215		238
Total deferred debits and other assets	2,040		2,040		2,179
Total assets	14,124		14,124		14,179
Equity
Common stock equity	4,874		4,874		4,957
Noncontrolling interests	3		3		4
Cumulative effect of change in accounting principle	4,877		4,877		4,961
Preferred stock of subsidiaries	34		34		34
Long-term debt, affiliate	309		309		309
Long-term debt, net	4,482		4,482		4,182
Total capitalization	9,702		9,702		9,486
Current liabilities
Current portion of long-term debt	0		0		300
Short-term debt	0		0		0
Notes payable to affiliated companies	259		259		175
Derivative liabilities	175		175		188
Other current liabilities	1,015		1,015		1,002
Total current liabilities	1,449		1,449		1,665
Deferred credits and other liabilities
Noncurrent income tax liabilities	863		863		528
Regulatory liabilities	796		796		1,084
Other liabilities and deferred credits	1,314		1,314		1,416
Total deferred credits and other liabilities	2,973		2,973		3,028
Total capitalization and liabilities	14,124		14,124		14,179
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			664	872
Investing activities
Gross property additions			(624)	(775)
Nuclear fuel additions			(13)	(32)
Proceeds from sales of assets to affiliated companies				0
Purchases of available-for-sale securities and other investments			(4,099)	(5,461)
Proceeds from available-for-sale securities and other investments			4,101	5,464
Changes in advances to affiliated companies			22	(13)
Return of investment in consolidated subsidiaries			0	0
Contributions to consolidated subsidiaries			0	0
Other investing activities			113	16
Net cash provided (used) by investing activities			(500)	(801)
Financing activities
Issuance of common stock, net			0	0
Dividends paid on common stock			0	0
Dividends paid to parent			(478)	(102)
Dividends paid to parent in excess of retained earnings			0	0
Payments of short-term debt with original maturities greater than 90 days				0
Net increase (decrease) in short-term debt			0	0
Proceeds from issuance of long-term debt, net			296	591
Retirement of long-term debt			(300)	(300)
Changes in advances from affiliated companies			84	(205)
Contributions from parent			10	33
Other financing activities			(12)	(9)
Net cash provided (used) by financing activities			(400)	8
Net increase (decrease) in cash and cash equivalents			(236)	79
Cash and cash equivalents at beginning of period			270	72
Cash and cash equivalents at end of period	34	151	34	151
Non-Guarantor Subsidiaries
Operating revenues
Operating revenues	1,332	1,414	3,525	3,794
Affiliate revenues	69	66	204	179
Total revenues	1,401	1,480	3,729	3,973
Operating expenses
Fuel used in electric generation	388	464	1,077	1,322
Purchased power	117	109	257	235
Operation and maintenance	332	301	1,026	977
Depreciation, amortization and accretion	136	124	396	369
Taxes other than on income	58	60	168	175
Other	38	10	38	10
Total operating expenses	1,069	1,068	2,962	3,088
Operating (loss) income	332	412	767	885
Other income (expense)
Interest income	1	2	1	5
Allowance for equity funds used during construction	15	17	53	45
Other, net	(5)	(3)	(7)	(7)
Total other income (expense), net	11	16	47	43
Interest charges
Interest charges	45	53	149	159
Allowance for borrowed funds used during construction	(4)	(5)	(15)	(14)
Total interest charges, net	41	48	134	145
(Loss) income from continuing operations before income tax and equity in earnings of consolidated subsidiaries	302	380	680	783
Income tax (benefit) expense	103	147	243	301
Equity in earnings of consolidated subsidiaries	0	0	0	0
Income from continuing operations before cumulative effect of change in accounting principle	199	233	437	482
Discontinued operations, net of tax	(1)	(2)	(2)	(3)
Cumulative effect of change in accounting principle, net of tax		2	0
Net income (loss)	198	233	435	479
Net (income) loss attributable to noncontrolling interests, net of tax	0	(2)	0	1
Net income attributable to controlling interests	198	231	435	480
ASSETS
Utility plant, net	11,578		11,578		10,961
Current assets
Cash and cash equivalents	69	293	69	293
Receivables, net	577		577		536
Notes receivable from affiliated companies	138		138		115
Regulatory assets	52		52		71
Derivative collateral posted	14		14		24
Income taxes receivable	0		0		0
Prepayments and other current assets	1,062		1,062		984
Total current assets	1,912		1,912		1,961
Deferred debits and other assets
Investment in consolidated subsidiaries	0		0		0
Regulatory assets	1,029		1,029		987
Goodwill	0		0		0
Nuclear decommissioning trust funds	992		992		1,017
Other assets and deferred debits	907		907		894
Total deferred debits and other assets	2,928		2,928		2,898
Total assets	16,418		16,418		15,820
Equity
Common stock equity	5,650		5,650		5,686
Noncontrolling interests	0		0		0
Cumulative effect of change in accounting principle	5,650		5,650		5,686
Preferred stock of subsidiaries	59		59		59
Long-term debt, affiliate	0		0		0
Long-term debt, net	3,693		3,693		3,693
Total capitalization	9,402		9,402		9,438
Current liabilities
Current portion of long-term debt	500		500		0
Short-term debt	0		0		0
Notes payable to affiliated companies	3		3		3
Derivative liabilities	93		93		53
Other current liabilities	1,104		1,104		1,184
Total current liabilities	1,700		1,700		1,240
Deferred credits and other liabilities
Noncurrent income tax liabilities	1,902		1,902		1,608
Regulatory liabilities	1,443		1,443		1,461
Other liabilities and deferred credits	1,971		1,971		2,073
Total deferred credits and other liabilities	5,316		5,316		5,142
Total capitalization and liabilities	16,418		16,418		15,820
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			909	1,205
Investing activities
Gross property additions			(911)	(893)
Nuclear fuel additions			(121)	(132)
Proceeds from sales of assets to affiliated companies				0
Purchases of available-for-sale securities and other investments			(437)	(466)
Proceeds from available-for-sale securities and other investments			408	451
Changes in advances to affiliated companies			(23)	242
Return of investment in consolidated subsidiaries			0	0
Contributions to consolidated subsidiaries			0	0
Other investing activities			14	0
Net cash provided (used) by investing activities			(1,070)	(798)
Financing activities
Issuance of common stock, net			0	0
Dividends paid on common stock			0	0
Dividends paid to parent			(450)	(75)
Dividends paid to parent in excess of retained earnings			0	(54)
Payments of short-term debt with original maturities greater than 90 days				0
Net increase (decrease) in short-term debt			0	0
Proceeds from issuance of long-term debt, net			496	0
Retirement of long-term debt			0	0
Changes in advances from affiliated companies			0	0
Contributions from parent			1	37
Other financing activities			(48)	(69)
Net cash provided (used) by financing activities			(1)	(161)
Net increase (decrease) in cash and cash equivalents			(162)	246
Cash and cash equivalents at beginning of period			231	47
Cash and cash equivalents at end of period	69	293	69	293
Other
Operating revenues
Operating revenues	0	0	0	0
Affiliate revenues	(69)	(66)	(204)	(179)
Total revenues	(69)	(66)	(204)	(179)
Operating expenses
Fuel used in electric generation	0	0	0	0
Purchased power	0	0	0	0
Operation and maintenance	(68)	(63)	(196)	(170)
Depreciation, amortization and accretion	0	0	0	0
Taxes other than on income	(1)	(1)	(5)	(5)
Other	0	0	0	0
Total operating expenses	(69)	(64)	(201)	(175)
Operating (loss) income	0	(2)	(3)	(4)
Other income (expense)
Interest income	0	(2)	0	(6)
Allowance for equity funds used during construction	0	0	0	0
Other, net	(1)	1	1	3
Total other income (expense), net	(1)	(1)	1	(3)
Interest charges
Interest charges	(1)	(1)	(1)	(5)
Allowance for borrowed funds used during construction	0	0	0	0
Total interest charges, net	(1)	(1)	(1)	(5)
(Loss) income from continuing operations before income tax and equity in earnings of consolidated subsidiaries	0	(2)	(1)	(2)
Income tax (benefit) expense	4	(2)	3	3
Equity in earnings of consolidated subsidiaries	(391)	(406)	(832)	(861)
Income from continuing operations before cumulative effect of change in accounting principle	(395)	(406)	(836)	(866)
Discontinued operations, net of tax	0	0	0	0
Cumulative effect of change in accounting principle, net of tax		0	0
Net income (loss)	(395)	(406)	(836)	(866)
Net (income) loss attributable to noncontrolling interests, net of tax	(1)	(1)	(2)	(2)
Net income attributable to controlling interests	(396)	(407)	(838)	(868)
ASSETS
Utility plant, net	86		86		90
Current assets
Cash and cash equivalents	0	0	0	0
Receivables, net	0		0		0
Notes receivable from affiliated companies	(262)		(262)		(177)
Regulatory assets	0		0		0
Derivative collateral posted	0		0		0
Income taxes receivable	0		0		0
Prepayments and other current assets	(186)		(186)		(273)
Total current assets	(448)		(448)		(450)
Deferred debits and other assets
Investment in consolidated subsidiaries	(14,196)		(14,196)		(14,316)
Regulatory assets	(1)		(1)		0
Goodwill	3,655		3,655		3,655
Nuclear decommissioning trust funds	0		0		0
Other assets and deferred debits	(479)		(479)		(469)
Total deferred debits and other assets	(11,021)		(11,021)		(11,130)
Total assets	(11,383)		(11,383)		(11,490)
Equity
Common stock equity	(10,524)		(10,524)		(10,643)
Noncontrolling interests	0		0		0
Cumulative effect of change in accounting principle	(10,524)		(10,524)		(10,643)
Preferred stock of subsidiaries	0		0		0
Long-term debt, affiliate	(36)		(36)		(36)
Long-term debt, net	0		0		0
Total capitalization	(10,560)		(10,560)		(10,679)
Current liabilities
Current portion of long-term debt	0		0		0
Short-term debt	0		0		0
Notes payable to affiliated companies	(262)		(262)		(178)
Derivative liabilities	0		0		0
Other current liabilities	(187)		(187)		(273)
Total current liabilities	(449)		(449)		(451)
Deferred credits and other liabilities
Noncurrent income tax liabilities	(455)		(455)		(443)
Regulatory liabilities	87		87		90
Other liabilities and deferred credits	(6)		(6)		(7)
Total deferred credits and other liabilities	(374)		(374)		(360)
Total capitalization and liabilities	(11,383)		(11,383)		(11,490)
Condensed Consolidating Statement of Cash Flows
Net cash provided (used) by operating activities			(928)	(196)
Investing activities
Gross property additions			0	25
Nuclear fuel additions			0	0
Proceeds from sales of assets to affiliated companies				0
Purchases of available-for-sale securities and other investments			0	0
Proceeds from available-for-sale securities and other investments			0	0
Changes in advances to affiliated companies			84	(205)
Return of investment in consolidated subsidiaries			0	(54)
Contributions to consolidated subsidiaries			11	56
Other investing activities			0	(1)
Net cash provided (used) by investing activities			95	(179)
Financing activities
Issuance of common stock, net			0	0
Dividends paid on common stock			0	0
Dividends paid to parent			928	177
Dividends paid to parent in excess of retained earnings			0	54
Payments of short-term debt with original maturities greater than 90 days				0
Net increase (decrease) in short-term debt			0	0
Proceeds from issuance of long-term debt, net			0	0
Retirement of long-term debt			0	0
Changes in advances from affiliated companies			(84)	205
Contributions from parent			(11)	(70)
Other financing activities			0	9
Net cash provided (used) by financing activities			833	375
Net increase (decrease) 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