XML 193 R133.htm IDEA: XBRL DOCUMENT v3.8.0.1
Merger, Acquisitions, and Dispositions - Pro Forma Consolidated Information (Details) - SOUTHERN Co GAS - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Business Acquisition [Line Items]    
Business acquisition, pro forma revenue $ 21,791 $ 21,430
Business acquisition, pro forma net income (loss) $ 2,591 $ 2,665
Business acquisition, pro forma earnings per share, basic $ 2.70 $ 2.85
Business acquisition, pro forma earnings per share, diluted $ 2.68 $ 2.84