Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Common stock, par value per share (in dollars per share)	$ 5	$ 5
Common stock, shares authorized	1,500,000,000	1,500,000,000
Southern Power [Member]
Amortization expense on other intangible assets	$ 12	$ 9
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000	1,000,000
Common stock, shares outstanding	1,000	1,000
Southern Power [Member] | 1.85% due 2017 [Member]
Fixed stated interest rate of debt obligation	1.85%	0.00%
Southern Power [Member] | 1.50% due 2018 [Member]
Fixed stated interest rate of debt obligation	1.50%	0.00%
Southern Power [Member] | 2.375% due 2020 [Member]
Fixed stated interest rate of debt obligation	2.375%	0.00%
Southern Power [Member] | 4.15% to 6.375% due Due 2025-2043 [Member]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	4.15%	4.15%