Income Taxes (Effective Income Tax Rate From Continuing Operations) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Income Taxes
Income tax at federal statutory rate	$ 52	$ 38	$ 86	$ 57
Depreciation		2	(1)	3
State income taxes, net of federal effect	6	5	11	9
Cross-border energy lease investments	21	(1)	20	(2)
Change in estimates and interest related to uncertain and effectively settled tax positions	(17)	1	(15)	10
Tax credits	(1)	(1)	(2)	(2)
Medicare Part D subsidy				4
Release of valuation allowance				(8)
Change in state deferred tax balances as a result of corporate restructuring		(8)		(8)
Other, net	(3)	(3)	(7)	(5)
State tax benefit related to prior years' asset dispositions	(4)		(4)
Consolidated income tax expense related to continuing operations	$ 54	$ 33	$ 88	$ 58
Income tax at federal statutory rate	35.00%	35.00%	35.00%	35.00%
Depreciation		1.40%	(0.40%)	1.70%
State income taxes, net of federal effect	4.00%	5.00%	4.50%	5.60%
Cross-border energy lease investments	14.10%	(1.20%)	8.20%	(1.50%)
Change in estimates and interest related to uncertain and effectively settled tax positions	(11.40%)	1.00%	(6.10%)	6.20%
Tax credits	(0.70%)	(0.90%)	(0.80%)	(1.20%)
Medicare Part D subsidy				2.20%
Release of valuation allowance				(4.80%)
Change in state deferred tax balances as a result of corporate restructuring		(7.80%)		(5.20%)
State tax benefits related to prior year' asset dispositions	(2.70%)		(1.60%)
Other, net	(2.10%)	(2.20%)	(2.90%)	(2.20%)
Consolidated income tax expense related to continuing operations	36.20%	30.30%	35.90%	35.80%

Change in estimates and interest related to uncertain tax positions

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INCOME TAXES [TO BE UPDATED BY TAX] [Abstract]

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Income Tax Rate, Change In Estimates And Interest Related To Uncertain Tax Positions

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A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 47

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Subparagraph 2
-Article 4

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The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate shall be the regular tax rate if there are alternative tax systems.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 47

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to changes in the valuation allowance for deferred tax assets.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to the deduction received under enacted tax laws for Medicare prescription drug benefits.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to the disposition of assets.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the different depreciation methods allowed under generally accepted accounting principles and enacted tax laws.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to rents and other costs from operating leases under enacted tax laws.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to nondeductible restructuring charges under enacted tax laws.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to all other items not otherwise listed in the existing taxonomy.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the state and local income tax expense (benefit), net of the federal tax benefit (expense) thereon, recorded during the period.

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The sum of the differences between the effective income tax rate and domestic federal statutory income tax rate that can be explained by all tax credits generated or utilized under enacted tax laws during the period.

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The sum of the current income tax expense (benefit) and the deferred income tax expense (benefit) pertaining to pretax income (loss) from continuing operations; income tax expense (benefit) may include interest and penalties on tax uncertainties based on the entity's accounting policy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 48
-Paragraph 15, 16, 19

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 45, 46

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The portion of the difference between total income tax expense (benefit) as reported in the Income Statement and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 26

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The portion of the difference between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to the subsidy for Medicare prescription drug benefits received tax-free.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS106-2
-Paragraph 12, 19

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The amount of income tax expense (benefit) for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The portion of the difference between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to the different depreciation methods allowed under generally accepted accounting principles and enacted tax laws.

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The portion of the difference between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to rents and other costs from operating leases under enacted tax laws.

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The portion of the difference between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to nondeductible restructuring charges under enacted tax laws.

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The portion of the difference, between total income tax expense (benefit) as reported in the Income Statement for the year/accounting period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to all other items not otherwise listed in the existing taxonomy.

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The portion of the difference, between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to state and local income tax expense (benefit).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Subparagraph 1
-Article 4

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The sum of the differences between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to tax credits.

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