Common Stock Shares Issued Previously Held In Treasury

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- Definition

Maximum Percentage of transfer performance shares to common stock based on actual Shareholder Return.

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No definition available.

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Minimum Percentage of transfer performance shares to common stock based on actual Shareholder Return.

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Number of employees participating in stock option plan.

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Share based compensation arrangement by share based payment award award expiration period.

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Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period

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- Definition

Share based compensation arrangement by share based payment award fair value assumptions weighted average grant date fair value.

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- Definition

Share based compensation arrangement by share based payment award number of shares reserved for issuance pursuant to stock based compensation plan.

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No definition available.

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- Definition

Stock issued during period shares company investment plan and employee and director stock plans.

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Undistributed retained earnings of the subsidiaries.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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The total cash inflow associated with the amount received from holders to acquire the entity's shares under incentive and share awards, including stock option exercises. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

Net number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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No definition available.

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Common Stock and Stock Compensation - Textual (Details) (USD $)	12 Months Ended			14 Months Ended
	Dec. 31, 2014 Employee	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014
Share-based Compensation [Abstract]
Stock Issued During Period, Shares, Southern Investment Plan and employee and director stock plans	20,800,000
Stock Issued During Period, Value, Southern Investment Plan and employee and director stock plans	$ 806,000,000
Common Stock Shares Issued Previously Held In Treasury				5,000,000
Share-based compensation arrangement by Share-based payment award, number of shares reserved for issuance, pursuant to Stock-based compensation plan	93,000,000
Number of employees participating in stock option program	5,437
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	12,812,691
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 2.20	$ 2.93	$ 3.39
Weighted average remaining contractual term for options outstanding	7 years
Weighted average remaining contractual term for options exercisable	6 years
Aggregate intrinsic value for options outstanding	342,000,000
Aggregate intrinsic value for options exercisable	214,000,000
Total unrecognized compensation cost related to award	10,000,000
Total compensation cost for award recognized in income	27,000,000	25,000,000	23,000,000
Total compensation cost for award recognized in income, tax benefit	10,000,000	10,000,000	9,000,000
Total intrinsic value of options exercised	125,000,000	77,000,000	162,000,000
Actual tax benefit for the tax deduction from stock option exercised	48,000,000	30,000,000	62,000,000
Cash received from issuance related to option exercise	400,000,000	204,000,000	397,000,000
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	200.00%
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	7,000,000	16,000,000
Undistributed retained earnings of the subsidiaries	6,400,000,000
Stock Options [Member]
Share-based Compensation [Abstract]
Option expiration period from date of grant	10 years
Total unrecognized compensation cost related to award, weighted average period	16 months
Performance Share Plan [Member]
Share-based Compensation [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 37.54	$ 40.50	$ 41.99
Total unrecognized compensation cost related to award	37,000,000
Total unrecognized compensation cost related to award, weighted average period	20 months
Total compensation cost for award recognized in income	33,000,000	31,000,000	28,000,000
Total compensation cost for award recognized in income, tax benefit	13,000,000	12,000,000	11,000,000
Vesting period of performance share units issued under Performance Share Plan	3 years
Performance share units, unvested	1,830,381	1,643,759
Performance share units, granted	1,057,813
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	755,716
Performance unit shares, forfeited	115,475
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number	105,783
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 49.71
Maximum [Member]
Share-based Compensation [Abstract]
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	20,000,000
Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period	3 years
Southern Company Common Stock [Member]
Share-based Compensation [Abstract]
Remaining shares available for awards	15,000,000
Georgia Power [Member]
Share-based Compensation [Abstract]
Number of employees participating in stock option program	1,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	2,034,150	1,509,662	1,269,725
Aggregate intrinsic value for options outstanding	73,000,000
Aggregate intrinsic value for options exercisable	51,000,000
Total intrinsic value of options exercised	19,000,000	16,000,000	34,000,000
Actual tax benefit for the tax deduction from stock option exercised	7,000,000	6,000,000	13,000,000
Vesting period of performance share units issued under Performance Share Plan	3 years
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	200.00%
Georgia Power [Member] \| Performance Shares [Member]
Share-based Compensation [Abstract]
Performance share units, granted	176,224	161,240	152,812
Georgia Power [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Option expiration period from date of grant	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 2.20	$ 2.93	$ 3.39
Georgia Power [Member] \| Performance Share Plan [Member]
Share-based Compensation [Abstract]
Total unrecognized compensation cost related to award	7,000,000
Total unrecognized compensation cost related to award, weighted average period	20 months
Total compensation cost for award recognized in income	6,000,000	6,000,000	6,000,000
Total compensation cost for award recognized in income, tax benefit	2,000,000	2,000,000	2,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 37.54	$ 40.50	$ 41.99
Georgia Power [Member] \| Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period	3 years
Mississippi Power [Member]
Share-based Compensation [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	578,256	345,830	278,709
Vesting period of performance share units issued under Performance Share Plan	3 years
Mississippi Power [Member] \| Performance Shares [Member]
Share-based Compensation [Abstract]
Total unrecognized compensation cost related to award	1,800,000
Total unrecognized compensation cost related to award, weighted average period	20 months
Total compensation cost for award recognized in income	1,700,000	1,500,000	1,200,000
Total compensation cost for award recognized in income, tax benefit	600,000	600,000	400,000
Vesting period of performance share units issued under Performance Share Plan	3 years
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	200.00%
Performance share units, granted	49,579	36,769	33,077
Mississippi Power [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Number of employees participating in stock option program	244
Option expiration period from date of grant	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 2.20	$ 2.93	$ 3.39
Aggregate intrinsic value for options outstanding	18,400,000
Aggregate intrinsic value for options exercisable	12,300,000
Total intrinsic value of options exercised	5,400,000	2,700,000	4,900,000
Actual tax benefit for the tax deduction from stock option exercised	2,100,000	1,100,000	1,900,000
Mississippi Power [Member] \| Performance Share Plan [Member]
Share-based Compensation [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 37.54	$ 40.50	$ 41.99
Mississippi Power [Member] \| Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period	3 years
Alabama Power [Member]
Share-based Compensation [Abstract]
Number of employees participating in stock option program	1,000
Aggregate intrinsic value for options outstanding	55,000,000
Aggregate intrinsic value for options exercisable	37,000,000
Total unrecognized compensation cost related to award	1,000,000
Total unrecognized compensation cost related to award, weighted average period	15 months
Total compensation cost for award recognized in income	5,000,000	4,000,000	4,000,000
Total compensation cost for award recognized in income, tax benefit	2,000,000	2,000,000	1,000,000
Total intrinsic value of options exercised	21,000,000	11,000,000	28,000,000
Actual tax benefit for the tax deduction from stock option exercised	8,000,000	4,000,000	11,000,000
Alabama Power [Member] \| Performance Shares [Member]
Share-based Compensation [Abstract]
Total unrecognized compensation cost related to award	5,000,000
Total unrecognized compensation cost related to award, weighted average period	20 months
Total compensation cost for award recognized in income	5,000,000	0	0
Total compensation cost for award recognized in income, tax benefit	2,000,000	0	0
Vesting period of performance share units issued under Performance Share Plan	3 years
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	200.00%
Performance share units, granted	176,070	141,355	131,820
Alabama Power [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Option expiration period from date of grant	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	2,027,298	1,319,038	1,099,315
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 2.20	$ 2.93	$ 3.39
Alabama Power [Member] \| Performance Share Plan [Member]
Share-based Compensation [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 37.54	$ 40.50	$ 41.99
Alabama Power [Member] \| Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period	3 years
Gulf Power [Member]
Share-based Compensation [Abstract]
Number of employees participating in stock option program	195
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	432,371	285,209	244,607
Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions Weighted Average Grant Date Fair Value	2.20	2.93	3.39
Aggregate intrinsic value for options outstanding	11,900,000
Aggregate intrinsic value for options exercisable	7,700,000
Total intrinsic value of options exercised	5,200,000	1,700,000	3,800,000
Actual tax benefit for the tax deduction from stock option exercised	2,000,000	600,000	1,500,000
Vesting period of performance share units issued under Performance Share Plan	3 years
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return	200.00%
Gulf Power [Member] \| Performance Shares [Member]
Share-based Compensation [Abstract]
Total unrecognized compensation cost related to award	1,300,000
Total compensation cost for award recognized in income		1,000,000	1,000,000
Total compensation cost for award recognized in income, tax benefit	400,000	400,000	400,000
Gulf Power [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Option expiration period from date of grant	10 years
Gulf Power [Member] \| Performance Share Plan [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions Weighted Average Grant Date Fair Value	$ 37.54	$ 40.50	$ 41.99
Total unrecognized compensation cost related to award, weighted average period	20 months
Performance share units, granted	37,829	30,627	29,444
Gulf Power [Member] \| Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period	3 years