Guarantee of Unsecured Senior Notes

No definition available.

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Data Type:	xbrli:monetaryItemType
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- Definition

jointly owned affiliate equity

+ References

No definition available.

+ Details

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- Definition

Jointly Owned Affiliate Long Term Debt

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=118943654&loc=d3e12069-110248

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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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.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(1))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

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- Details

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- Details

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- Details

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- Details

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CONTINGENCIES, COMMITMENTS, AND GUARANTEES - Guarantees (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Oct. 31, 2017	Dec. 31, 2014
Recorded Unconditional Purchase Obligation [Line Items]
Short-term debt	$ 2,055	$ 2,915
Alabama Power
Recorded Unconditional Purchase Obligation [Line Items]
Jointly owned affiliate equity	87
Jointly owned affiliate long term debt	$ 100
Ownership percentage, equity method investment	50.00%
Southern Company Gas
Recorded Unconditional Purchase Obligation [Line Items]
Short-term debt	$ 650	$ 650
SEGCO \| Maturity December 1, 2018 \| Alabama Power
Recorded Unconditional Purchase Obligation [Line Items]
Guarantee of unsecured senior notes	100
SEGCO \| Alabama Power
Recorded Unconditional Purchase Obligation [Line Items]
Short-term debt	26
Atlantic Coast Pipeline \| Southern Company Gas
Recorded Unconditional Purchase Obligation [Line Items]
Ownership percentage, equity method investment				5.00%
Maximum guarantee	$ 88
Revolving Credit Facility \| Atlantic Coast Pipeline \| Southern Company Gas
Recorded Unconditional Purchase Obligation [Line Items]
Revolving credit facility executed			$ 3,400