Financing - Capital Leases Narrative (Details) $ in Millions	Dec. 31, 2018 USD ($) leased_asset_unit	Dec. 31, 2017 USD ($) leased_asset_unit
Debt Instrument [Line Items]
Capitalized lease obligations	$ 197	$ 204
SCS
Debt Instrument [Line Items]
Capitalized lease obligations	$ 178	177
SCS \| Capital Lease Obligations \| Minimum
Debt Instrument [Line Items]
Fixed stated interest rate of debt obligation	1.60%
SCS \| Capital Lease Obligations \| Maximum
Debt Instrument [Line Items]
Fixed stated interest rate of debt obligation	4.70%
Georgia Power
Debt Instrument [Line Items]
Capitalized lease obligations	$ 142	154
Georgia Power \| Office buildings
Debt Instrument [Line Items]
Capitalized lease obligations	15	22
Georgia Power \| PPAs
Debt Instrument [Line Items]
Capitalized lease obligations	$ 128	$ 132
Capital leased assets, number of units \| leased_asset_unit	2	2
Georgia Power \| Minimum \| PPAs
Debt Instrument [Line Items]
Fixed stated interest rate of debt obligation	11.00%
Georgia Power \| Maximum \| PPAs
Debt Instrument [Line Items]
Fixed stated interest rate of debt obligation	12.00%
Georgia Power \| Capital Lease Obligations
Debt Instrument [Line Items]
Fixed stated interest rate of debt obligation	7.90%

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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(22))
-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 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737

Reference 3: 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))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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