v3.8.0.1
Document and Entity Information
9 Months Ended
Sep. 30, 2017
shares
Document Information [Line Items]  
Entity Registrant Name SOUTHERN CO
Entity Central Index Key 0000092122
Document Type 10-Q
Document Period End Date Sep. 30, 2017
Amendment Flag false
Document Fiscal Year Focus 2017
Document Fiscal Period Focus Q3
Current Fiscal Year End Date --12-31
Entity Filer Category Large Accelerated Filer
Entity Common Stock, Shares Outstanding (in shares) 1,003,627,691
ALABAMA POWER CO  
Document Information [Line Items]  
Entity Registrant Name ALABAMA POWER CO
Entity Central Index Key 0000003153
Entity Filer Category Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares) 30,537,500
GEORGIA POWER CO  
Document Information [Line Items]  
Entity Registrant Name GEORGIA POWER CO
Entity Central Index Key 0000041091
Entity Filer Category Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares) 9,261,500
GULF POWER CO  
Document Information [Line Items]  
Entity Registrant Name GULF POWER CO
Entity Central Index Key 0000044545
Entity Filer Category Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares) 7,392,717
MISSISSIPPI POWER CO  
Document Information [Line Items]  
Entity Registrant Name MISSISSIPPI POWER CO
Entity Central Index Key 0000066904
Entity Filer Category Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares) 1,121,000
SOUTHERN POWER CO  
Document Information [Line Items]  
Entity Registrant Name SOUTHERN POWER CO
Entity Central Index Key 0001160661
Entity Filer Category Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares) 1,000
SOUTHERN Co GAS  
Document Information [Line Items]  
Entity Registrant Name SOUTHERN Co GAS
Entity Central Index Key 0001004155
Entity Filer Category Non-accelerated Filer
Entity Common Stock, Shares Outstanding (in shares) 100