Business Acquisition, Conversion Ratio, Percentage of Underlying Stock Award Units

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- Definition

Percentage of Shares to Common Stock Based on Price Metrics and Performance Goals

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No definition available.

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- Definition

Share Based Compensation, Shares Vested and Issued Each Year Employee Remains In Service At Each Vest Year, Percentage

+ References

No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Number of Performance Criteria

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No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Performance Measure One, Percent of Award

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No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Performance Measure Two, Percent of Award

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Performance Period

+ References

No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
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- Definition

Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

+ References

No definition available.

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- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

+ References

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- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

+ References

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- Definition

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

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- Definition

Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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- Definition

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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- Definition

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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

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

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

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

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-Name Accounting Standards Codification
-Topic 718
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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 3
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Common Stock and Stock Compensation - Textual Southern Company Gas Awards (Details)	6 Months Ended		12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares	Jun. 30, 2016 USD ($) shares	Dec. 31, 2017 USD ($) performance_measure $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Jul. 01, 2016 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax credit carryforward			$ 2,100,000,000
Shares vested and issued each year employee remains in service			33.00%
Proceeds from stock options exercised			$ 239,000,000	$ 448,000,000	$ 154,000,000
Aggregate intrinsic value for options outstanding			119,000,000
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 4,000,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instrument, granted (in shares) \| shares			600,000
Performance share units, unvested (in shares) \| shares			700,000
Total compensation cost for award recognized in income			$ 25,000,000
Total unrecognized compensation cost related to award, weighted average period			13 months
Equity instruments, vested (in shares) \| shares			100,000
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 10,000,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instrument, granted (in shares) \| shares			1,220,000.00
Performance share units, unvested (in shares) \| shares	3,240,000.00		2,890,000.00	3,240,000.00
Total compensation cost for award recognized in income			$ 74,000,000	$ 96,000,000	88,000,000
Total unrecognized compensation cost related to award, weighted average period			21 months
Equity instruments, vested (in shares) \| shares			1,500,000.00
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 29,000,000	$ 37,000,000	$ 34,000,000
Parent Company \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instrument, granted (in shares) \| shares	742,461
Equity instrument granted in period, weighted average grant date fair value (in dollars per share) \| $ / shares	$ 53.83		$ 49.25
Merger-related expenses			$ 13,000,000
Total compensation cost for award recognized in income			$ 12,000,000
ALABAMA POWER CO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested and issued each year employee remains in service			33.00%
Proceeds from stock options exercised			$ 0
Aggregate intrinsic value for options outstanding			$ 17,000,000
ALABAMA POWER CO \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instrument, granted (in shares) \| shares			58,001
Equity instrument granted in period, weighted average grant date fair value (in dollars per share) \| $ / shares			$ 49.21
Total compensation cost for award recognized in income			$ 3,000,000
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 1,000,000
ALABAMA POWER CO \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instrument, granted (in shares) \| shares			135,502	249,065	214,709
Equity instrument granted in period, weighted average grant date fair value (in dollars per share) \| $ / shares			$ 49.07	$ 45.15	$ 46.42
Total compensation cost for award recognized in income			$ 9,000,000	$ 15,000,000	$ 13,000,000
Total unrecognized compensation cost related to award, weighted average period			21 months
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 4,000,000	$ 6,000,000	5,000,000
SOUTHERN Co GAS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Merger-related expenses	$ 41,000,000		$ 0
Shares vested and issued each year employee remains in service			33.00%
SOUTHERN Co GAS \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award requisite service period			3 years
Equity instrument, granted (in shares) \| shares		25,166	109,969	47,546
Equity instrument granted in period, weighted average grant date fair value (in dollars per share) \| $ / shares			$ 49.23
Total compensation cost for award recognized in income			$ 4,000,000
Compensation not yet recognized			$ 1,000,000
Total unrecognized compensation cost related to award, weighted average period			13 months
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 2,000,000
SOUTHERN Co GAS \| Change In Control Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost for award recognized in income	4,000,000		12,000,000
Tax credit carryforward	$ 1,000,000		6,000,000	$ 1,000,000
Compensation not yet recognized			$ 8,000,000
Total unrecognized compensation cost related to award, weighted average period			18 months
SOUTHERN Co GAS \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award requisite service period			3 years
Expiration period			10 years
SOUTHERN Co GAS \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instrument, granted (in shares) \| shares			300,000
Equity instrument granted in period, weighted average grant date fair value (in dollars per share) \| $ / shares			$ 49.27
Total compensation cost for award recognized in income			$ 8,000,000
Total unrecognized compensation cost related to award, weighted average period			21 months
Number of performance criteria \| performance_measure			2
Performance measure one, % of award				75.00%
Performance measure two, % of award				25.00%
Performance period				3 years
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense			$ 3,000,000
SOUTHERN Co GAS \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instrument, granted (in shares) \| shares			303,618
Performance share units, unvested (in shares) \| shares	398,832			398,832
Equity instruments, vested (in shares) \| shares			699,960
SOUTHERN Co GAS \| Predecessor
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Merger-related expenses		$ 56,000,000			$ 44,000,000
Compensation not yet recognized	$ 0			$ 0
Aggregate intrinsic value for options outstanding	$ 13,000,000	3,000,000		13,000,000
SOUTHERN Co GAS \| Predecessor \| Cash and Stock-based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost for award recognized in income		$ 24,000,000		$ 40,000,000
SOUTHERN Co GAS \| Minimum \| Change In Control Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares to common stock based on price metrics and performance goals			0.00%
SOUTHERN Co GAS \| Maximum \| Change In Control Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of shares to common stock based on price metrics and performance goals			100.00%
Southern Company \| SOUTHERN Co GAS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business acquisition share price (in dollars per share) \| $ / shares						$ 66
Conversion ratio, percentage of underlying stock award units						125.00%