Fair Value Measurements (Details 1) (USD $) In Millions	Sep. 30, 2011
Alabama Power [Member] \| Trust owned life insurance [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	$ 82
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	15 days
Alabama Power [Member] \| Money market funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	445
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Georgia Power [Member] \| Corporate bonds - commingled funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	37
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	1 to 3 days
Georgia Power [Member] \| Other - commingled funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	62
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Georgia Power [Member] \| Money market funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	45
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Gulf Power [Member] \| Money market funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	14
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Mississippi Power [Member] \| Money market funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	85
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Southern Power [Member] \| Money market funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	196
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Corporate bonds - commingled funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	37
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	1 to 3 days
Other - commingled funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	62
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable
Trust owned life insurance [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	82
Unfunded Commitments	0
Redemption Frequency	Daily
Redemption Notice Period	15 days
Money market funds [Member]
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments
Fair Value	1,286
Unfunded Commitments	$ 0
Redemption Frequency	Daily
Redemption Notice Period	Not applicable

Fair value investments entities that calculate net asset value per share redemption.

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- Definition

Fair value investments entities that calculate net asset value per share redemption notice period.

+ Details

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- Definition

Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments.

+ Details

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- Definition

This element represents the total fair market value of investments in certain entities that calculate net asset value per share (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments). This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements, but may also be used in both the balance sheet and disclosure in the same submission. This item represents alternative investments as of the balance sheet date which may include investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds, and any other investment in which investee management calculates net asset value per share as the primary metric for investment value.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph a

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 5

-Subparagraph a

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19296-110258

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Subparagraph (a)

-Paragraph 6A

-URI http://asc.fasb.org/extlink&oid=6925170&loc=SL6742756-110258

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 6A

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=SL6742756-110258

+ Details

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