Retirement Benefits (Details) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year			$ 0
Pension Plans [Member] \| Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	$ 62,000,000	$ 64,000,000	124,000,000	$ 128,000,000
Interest cost	101,000,000	111,000,000	201,000,000	222,000,000
Expected return on plan assets	(187,000,000)	(181,000,000)	(374,000,000)	(362,000,000)
Amortization:
Prior service costs	3,000,000	7,000,000	7,000,000	13,000,000
Net (gain)/loss	37,000,000	54,000,000	75,000,000	108,000,000
Net cost	16,000,000	55,000,000	33,000,000	109,000,000
Pension Plans [Member] \| Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	15,000,000	15,000,000	29,000,000	30,000,000
Interest cost	24,000,000	27,000,000	48,000,000	53,000,000
Expected return on plan assets	(46,000,000)	(44,000,000)	(92,000,000)	(89,000,000)
Amortization:
Prior service costs	0	1,000,000	1,000,000	3,000,000
Net (gain)/loss	10,000,000	13,000,000	20,000,000	27,000,000
Net cost	3,000,000	12,000,000	6,000,000	24,000,000
Pension Plans [Member] \| Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	18,000,000	18,000,000	35,000,000	36,000,000
Interest cost	34,000,000	39,000,000	68,000,000	77,000,000
Expected return on plan assets	(65,000,000)	(63,000,000)	(129,000,000)	(126,000,000)
Amortization:
Prior service costs	2,000,000	2,000,000	3,000,000	5,000,000
Net (gain)/loss	13,000,000	19,000,000	27,000,000	38,000,000
Net cost	2,000,000	15,000,000	4,000,000	30,000,000
Pension Plans [Member] \| Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	3,000,000	3,000,000	6,000,000	6,000,000
Interest cost	4,000,000	5,000,000	9,000,000	10,000,000
Expected return on plan assets	(8,000,000)	(8,000,000)	(17,000,000)	(16,000,000)
Amortization:
Prior service costs	1,000,000	0	1,000,000	0
Net (gain)/loss	1,000,000	2,000,000	3,000,000	5,000,000
Net cost	1,000,000	2,000,000	2,000,000	5,000,000
Pension Plans [Member] \| Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	3,000,000	3,000,000	6,000,000	6,000,000
Interest cost	5,000,000	6,000,000	10,000,000	11,000,000
Expected return on plan assets	(8,000,000)	(9,000,000)	(17,000,000)	(17,000,000)
Amortization:
Prior service costs	0	1,000,000	0	1,000,000
Net (gain)/loss	1,000,000	2,000,000	3,000,000	5,000,000
Net cost	1,000,000	3,000,000	2,000,000	6,000,000
Other Postretirement Benefits [Member] \| Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	6,000,000	5,000,000	11,000,000	11,000,000
Interest cost	17,000,000	20,000,000	35,000,000	39,000,000
Expected return on plan assets	(14,000,000)	(14,000,000)	(28,000,000)	(29,000,000)
Amortization:
Prior service costs	1,000,000	1,000,000	3,000,000	2,000,000
Net (gain)/loss	4,000,000	4,000,000	7,000,000	9,000,000
Net cost	14,000,000	16,000,000	28,000,000	32,000,000
Other Postretirement Benefits [Member] \| Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	2,000,000	2,000,000	3,000,000	3,000,000
Interest cost	4,000,000	5,000,000	9,000,000	10,000,000
Expected return on plan assets	(7,000,000)	(7,000,000)	(13,000,000)	(13,000,000)
Amortization:
Prior service costs	1,000,000	0	2,000,000	1,000,000
Net (gain)/loss	1,000,000	1,000,000	1,000,000	1,000,000
Net cost	1,000,000	1,000,000	2,000,000	2,000,000
Other Postretirement Benefits [Member] \| Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	1,000,000	1,000,000	3,000,000	3,000,000
Interest cost	7,000,000	9,000,000	15,000,000	17,000,000
Expected return on plan assets	(5,000,000)	(6,000,000)	(11,000,000)	(12,000,000)
Amortization:
Prior service costs	1,000,000	0	1,000,000	0
Net (gain)/loss	2,000,000	3,000,000	4,000,000	6,000,000
Net cost	6,000,000	7,000,000	12,000,000	14,000,000
Other Postretirement Benefits [Member] \| Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	1,000,000	0	1,000,000	0
Interest cost	0	1,000,000	1,000,000	2,000,000
Expected return on plan assets	(1,000,000)	(1,000,000)	(1,000,000)	(1,000,000)
Amortization:
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	0	0	1,000,000	1,000,000
Other Postretirement Benefits [Member] \| Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	1,000,000	1,000,000	1,000,000	1,000,000
Interest cost	1,000,000	1,000,000	2,000,000	2,000,000
Expected return on plan assets	(1,000,000)	(1,000,000)	(1,000,000)	(1,000,000)
Amortization:
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	$ 1,000,000	$ 1,000,000	$ 2,000,000	$ 2,000,000

Defined Benefit Plan, Net Periodic Benefit Cost, Amortization [Abstract]

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The amount of gains or losses recognized in net periodic benefit cost.

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- Definition

The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(1)
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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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An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References

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-Publisher FASB
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The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

+ References

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The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position.

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