Retirement Benefits - Schedule Of Health Care Cost Trend Rates (Details) - Other Postretirement Benefit Plan [Member]	12 Months Ended
Dec. 31, 2015
Pre Sixty Five [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	6.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Post Sixty Five Medical [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	5.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Post Sixty Five Prescription [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	10.00%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2025
Alabama Power [Member] \| Pre Sixty Five [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	6.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Alabama Power [Member] \| Post Sixty Five Medical [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	5.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Alabama Power [Member] \| Post Sixty Five Prescription [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	10.00%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2025
Georgia Power [Member] \| Pre Sixty Five [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	6.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Georgia Power [Member] \| Post Sixty Five Medical [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	5.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Georgia Power [Member] \| Post Sixty Five Prescription [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	10.00%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2025
Gulf Power [Member] \| Pre Sixty Five [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	6.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Gulf Power [Member] \| Post Sixty Five Medical [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	5.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Gulf Power [Member] \| Post Sixty Five Prescription [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	10.00%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2025
Mississippi Power [Member] \| Pre Sixty Five [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	6.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Mississippi Power [Member] \| Post Sixty Five Medical [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	5.50%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2024
Mississippi Power [Member] \| Post Sixty Five Prescription [Member]
Defined Benefit Plan Disclosure [Line Items]
Initial Cost Trend Rate	10.00%
Ultimate Cost Trend Rate	4.50%
Year That Ultimate Rate Is Reached	2025

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.

No definition available.

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- Definition

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Health Care Cost Trend Rate
-URI http://asc.fasb.org/extlink&oid=6514820

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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- Definition

The ultimate trend rate for health care costs.

+ 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 (l)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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- Definition

Year the ultimate health care cost trend rate is expected to be reached, in CCYY format.

+ References

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