Fair Value Measurements (Details 3) (USD $) In Millions	Jun. 30, 2011
Long-term debt:
Long-term debt, Carrying Amount	$ 19,812
Long-term debt, Fair Value	20,757
Alabama Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	6,236
Long-term debt, Fair Value	6,602
Georgia Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	8,740
Long-term debt, Fair Value	9,088
Gulf Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	1,235
Long-term debt, Fair Value	1,300
Mississippi Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	661
Long-term debt, Fair Value	693
Southern Power [Member]
Long-term debt:
Long-term debt, Carrying Amount	1,300
Long-term debt, Fair Value	$ 1,390