Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Long-term debt:
Long-term debt, Carrying Amount	$ 21,451
Long-term debt, Fair Value	23,477
Alabama Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	6,130
Long-term debt, Fair Value	6,893
Georgia Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	9,856
Long-term debt, Fair Value	10,703
Gulf Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	1,246
Long-term debt, Fair Value	1,384
Mississippi Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	1,576
Long-term debt, Fair Value	1,690
Southern Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	1,306
Long-term debt, Fair Value	$ 1,416