Fair Value Measurements - Financial Instruments for which Carrying Amount did not Equal Fair Value (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Southern Company [Member]
Long-term debt:
Long-term debt, Carrying Amount	$ 22,542
Long-term debt, Fair Value	23,883
Alabama Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	6,229
Long-term debt, Fair Value	6,800
Georgia Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	9,557
Long-term debt, Fair Value	10,112
Gulf Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	1,246
Long-term debt, Fair Value	1,306
Mississippi Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	2,577
Long-term debt, Fair Value	2,571
Southern Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	1,629
Long-term debt, Fair Value	$ 1,752