Regulatory Assets and Liabilities Regulatory Assets and Liabilities - Table (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Regulatory Assets and Liabilities
Current regulatory assets	$ 481	$ 561
Non-current regulatory assets	8,994	9,131
Regulatory assets	9,475	9,692
Current regulatory liabilities	184	212
Non-current regulatory liabilities	0	1
Regulatory liabilities	184	213
Fuel cost adjustment tax equivalents
Regulatory Assets and Liabilities
Current regulatory liabilities	182	176
Fuel cost adjustment receivable/payable
Regulatory Assets and Liabilities
Current regulatory liabilities	0	29
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory liabilities	2	7
Non-current regulatory liabilities	0	1
Unrealized gains/losses on commodity derivatives
Regulatory Assets and Liabilities
Current regulatory assets	134	183
Non-current regulatory assets	72	139
Deferred nuclear generating units
Regulatory Assets and Liabilities
Current regulatory assets	237	237
Non-current regulatory assets	1,255	1,438
Regulatory assets	1,500
Environmental agreements
Regulatory Assets and Liabilities
Current regulatory assets	54	73
Non-current regulatory assets	108	189
Fuel cost adjustment receivable/payable
Regulatory Assets and Liabilities
Current regulatory assets	9	0
Environmental cleanup costs - Kingston ash spill
Regulatory Assets and Liabilities
Current regulatory assets	47	68
Non-current regulatory assets	421	681
Deferred pension costs and other post-retirement benefits costs
Regulatory Assets and Liabilities
Non-current regulatory assets	4,297	4,076
Unrealized losses on interest rate derivatives
Regulatory Assets and Liabilities
Non-current regulatory assets	957	808
Nuclear decommissioning costs
Regulatory Assets and Liabilities
Non-current regulatory assets	931	893
Non-nuclear decommissioning costs
Regulatory Assets and Liabilities
Non-current regulatory assets	645	571
Other non-current regulatory assets
Regulatory Assets and Liabilities
Non-current regulatory assets	$ 308	$ 336

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 340

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

+ References

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Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

+ References

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- Definition

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 405

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394

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The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period.

+ References

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The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.24)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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