Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Interest capitalized	$ 53	$ 72
ALABAMA POWER CO
Interest capitalized	15	10
GEORGIA POWER CO
Interest capitalized	19	17
GULF POWER CO
Interest capitalized	0	0
MISSISSIPPI POWER CO
Interest paid	57	73
Interest capitalized	0	28
SOUTHERN POWER CO
Interest capitalized	14	7
SOUTHERN Co GAS
Interest capitalized	$ 5	$ 9

Amount of cash paid for interest, including, but not limited to, capitalized interest and payment to settle zero-coupon bond attributable to accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount; classified as operating and investing activities.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4297-108586

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration