The capitalized costs incurred during the period (excluded from amortization) to operate and maintain wells and related equipment and facilities, including depreciation and applicable operating costs of support equipment and facilities and other costs of operating and maintaining those wells and related equipment and facilities. They become part of the cost of oil and gas produced. Examples of production costs (sometimes called lifting costs) are: costs of labor to operate the wells and related equipment and facilities; repairs and maintenance; materials, supplies, and fuel consumed and supplies utilized in operating the wells and related equipment and facilities; property taxes and insurance applicable to proved properties and wells and related equipment and facilities; severance taxes; some support equipment or facilities may serve two or more oil and gas producing activities and may also serve transportation, refining, and marketing activities. To the extent that the support equipment and facilities are used in oil and gas producing activities, their depreciation and applicable operating costs become exploration, development or production costs, as appropriate. Depreciation, depletion, and amortization of capitalized acquisition, exploration, and development costs are not production costs but also become part of the cost of oil and gas produced along with production (lifting) costs identified above.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-10(c)(5))
-URI http://asc.fasb.org/extlink&oid=82851474&loc=d3e511914-122862

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-10(c)(3)(ii)(A))
-URI http://asc.fasb.org/extlink&oid=82851474&loc=d3e511914-122862

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-10(c)(7)(ii))
-URI http://asc.fasb.org/extlink&oid=82851474&loc=d3e511914-122862

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-10(a)(20))
-URI http://asc.fasb.org/extlink&oid=82851474&loc=d3e511914-122862

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Contingencies and Regulatory Matters - Kemper County Energy Facility (Details) - MISSISSIPPI POWER CO - USD ($) $ in Millions		3 Months Ended		9 Months Ended	12 Months Ended
	Aug. 06, 2018	Dec. 31, 2018	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2017
Loss Contingencies [Line Items]
Accrued plant closure costs			$ 30	$ 30			$ 35
Kemper County Energy Facility
Loss Contingencies [Line Items]
Public utilities, charges to income			0	45
Public utilities, charges to income, after tax				34
Accrued plant closure costs			$ 20	$ 20
Reserve Margin Plan \| Plant Watson, Unit 4
Loss Contingencies [Line Items]
Accelerated retirement period	2 years
Reserve Margin Plan \| Plant Watson, Unit 5
Loss Contingencies [Line Items]
Accelerated retirement period	7 years
Reserve Margin Plan \| Plant Greene County Units 1 and 2
Loss Contingencies [Line Items]
Accelerated retirement period	4 years
Scenario, Forecast \| Kemper County Energy Facility
Loss Contingencies [Line Items]
Production costs, period cost		$ 2			$ 4	$ 8