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Financing - Narrative (Details)			1 Months Ended			3 Months Ended	6 Months Ended
Financing - Narrative (Details)	Jun. 27, 2016 USD ($)	Mar. 08, 2016 USD ($)	May 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Jan. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 EUR (€)	Mar. 14, 2016 USD ($)	Jan. 29, 2016 USD ($)	Jan. 19, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding						$ 1,900,000,000	$ 1,900,000,000
Maximum Borrowing Capacity						6,500,000,000	6,500,000,000
Senior Note Issuances							10,791,000,000
Remaining Borrowing Capacity						6,387,000,000	6,387,000,000
Alabama Power [Member]
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding						890,000,000	890,000,000
Fixed rate pollution control revenue bonds outstanding						87,000,000	87,000,000
Maximum Borrowing Capacity						1,335,000,000	1,335,000,000
Senior Note Issuances							400,000,000
Repayments of Senior Debt							200,000,000	$ 250,000,000
Capital contributions from parent company							237,000,000	10,000,000
Remaining Borrowing Capacity						1,335,000,000	1,335,000,000
Alabama Power [Member] \| Series FF [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					5.20%
Alabama Power [Member] \| Senior Notes [Member] \| Series 2016A [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage					4.30%
Alabama Power [Member] \| Unsecured Debt [Member] \| Series FF [Member]
Debt Instrument [Line Items]
Repayments of Senior Debt					$ 200,000,000
Alabama Power [Member] \| Bank Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 45,000,000
Debt Instrument, Interest Rate, Stated Percentage				2.38%
Georgia Power [Member]
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding						868,000,000	868,000,000
Fixed rate pollution control revenue bonds outstanding						212,000,000	212,000,000
Line of Credit Facility, Current Borrowing Capacity						300,000,000	300,000,000
Maximum Borrowing Capacity						1,750,000,000	1,750,000,000
Senior Note Issuances							650,000,000
Repayments of Senior Debt							500,000,000	125,000,000
Capital contributions from parent company							239,000,000	23,000,000
Remaining Borrowing Capacity						$ 1,732,000,000	$ 1,732,000,000
Georgia Power [Member] \| Senior Notes [Member] \| Series 2016A [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 325,000,000
Debt Instrument, Interest Rate, Stated Percentage				3.25%
Georgia Power [Member] \| Senior Notes [Member] \| Series 2016B [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 325,000,000
Debt Instrument, Interest Rate, Stated Percentage				2.40%
Georgia Power [Member] \| Unsecured Debt [Member] \| Series 2013B [Member]
Debt Instrument [Line Items]
Repayments of Senior Debt				$ 250,000,000
Georgia Power [Member] \| Line of Credit [Member] \| FFB Credit Facility due 2044 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage						2.571%	2.571%		2.571%
Gulf Power [Member]
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding						$ 82,000,000	$ 82,000,000
Fixed rate pollution control revenue bonds outstanding						21,000,000	21,000,000
Maximum Borrowing Capacity						280,000,000	280,000,000
Senior Note Issuances							0
Repayments of Senior Debt							125,000,000	0
Remaining Borrowing Capacity						280,000,000	280,000,000
Gulf Power [Member] \| Series 2011A [Member]
Debt Instrument [Line Items]
Redemption Amount Of Principal Notes			$ 125,000,000
Gulf Power [Member] \| Senior Notes [Member] \| Series 2011A [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			5.75%
Gulf Power [Member] \| Bank Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 100,000,000
Debt instrument term			11 months
Mississippi Power [Member]
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding						40,000,000	40,000,000
Line of Credit Facility, Current Borrowing Capacity						100,000,000	100,000,000			$ 50,000,000	$ 50,000,000	$ 100,000,000
Maximum Borrowing Capacity						175,000,000	175,000,000
Senior Note Issuances							0
Promissory Note					$ 275,000,000		0	301,000,000
Capital contributions from parent company	$ 225,000,000						226,000,000	77,000,000
Long-term Debt, Affiliated						551,000,000	551,000,000						$ 576,000,000
Remaining Borrowing Capacity						150,000,000	150,000,000
Mississippi Power [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Redemption Amount Of Principal Notes		$ 300,000,000
Mississippi Power [Member] \| Unsecured Debt [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity		900,000,000
Maximum Borrowing Capacity		1,200,000,000.00
Remaining Borrowing Capacity		300,000,000
Mississippi Power [Member] \| Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Repayments of Senior Debt		$ 900,000,000
Mississippi Power [Member] \| Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						10,000,000	10,000,000
Traditional Operating Companies [Member]
Debt Instrument [Line Items]
Fixed rate pollution control revenue bonds outstanding						320,000,000	320,000,000
Southern Power [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity						600,000,000	600,000,000
Senior Note Issuances							1,241,000,000
Capital contributions from parent company							300,000,000	$ 0
Remaining Borrowing Capacity						$ 560,000,000	$ 560,000,000
Southern Power [Member] \| Senior Notes [Member] \| Series 2016A [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount \| €									€ 600,000,000
Debt Instrument, Interest Rate, Stated Percentage						1.00%	1.00%		1.00%
Southern Power [Member] \| Senior Notes [Member] \| Series 2016B [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount \| €									€ 500,000,000
Debt Instrument, Interest Rate, Stated Percentage						1.85%	1.85%		1.85%
Southern Power [Member] \| Project Credit Facilities [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity						$ 769,000,000	$ 769,000,000
Debt, Weighted Average Interest Rate						2.02%	2.02%		2.02%
Maximum Borrowing Capacity						$ 769,000,000	$ 769,000,000
Line of Credit Facility, Average Amount Outstanding						$ 586,000,000	586,000,000
Debt Instrument, Interest Rate During Period						2.03%
Southern Power [Member] \| Letter of Credit [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity						$ 149,000,000	149,000,000
Remaining Borrowing Capacity						65,000,000	65,000,000
Southern Company [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity						2,250,000,000	2,250,000,000
Senior Note Issuances			$ 8,500,000,000.0				8,500,000,000
Remaining Borrowing Capacity						$ 2,250,000,000	2,250,000,000
Southern Company [Member] \| Senior Notes [Member] \| Senior Notes due July 1, 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 500,000,000
Debt Instrument, Interest Rate, Stated Percentage			1.55%
Southern Company [Member] \| Senior Notes [Member] \| Senior Notes due July 1, 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 1,000,000,000
Debt Instrument, Interest Rate, Stated Percentage			1.85%
Southern Company [Member] \| Senior Notes [Member] \| Senior Notes due July 1, 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 1,500,000,000.0
Debt Instrument, Interest Rate, Stated Percentage			2.35%
Southern Company [Member] \| Senior Notes [Member] \| Senior Notes due July 1, 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 1,250,000,000.00
Debt Instrument, Interest Rate, Stated Percentage			2.95%
Southern Company [Member] \| Senior Notes [Member] \| Senior Notes due July 1, 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 1,750,000,000.00
Debt Instrument, Interest Rate, Stated Percentage			3.25%
Southern Company [Member] \| Senior Notes [Member] \| Senior Notes due July 1, 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 500,000,000
Debt Instrument, Interest Rate, Stated Percentage			4.25%
Southern Company [Member] \| Senior Notes [Member] \| Senior Notes due July 1, 2046 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 2,000,000,000
Debt Instrument, Interest Rate, Stated Percentage			4.40%
Southern Power's Subsidiary(ies) [Member]
Debt Instrument [Line Items]
Proceeds from Long-term Lines of Credit							$ 632,000,000
Southern Power's Subsidiary(ies) [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate						2.00%	2.00%		2.00%
Southern Power's Subsidiary(ies) [Member] \| Letter of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 16,000,000	$ 16,000,000