Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
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	$ 8,279	$ 5,614
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] | 4.875% due 2015
Fixed stated interest rate of debt obligation	0.00%	4.875%
Southern Power [Member] | 6.375% due 2036
Fixed stated interest rate of debt obligation	6.375%	6.375%
Southern Power [Member] | 5.15% due 2041
Fixed stated interest rate of debt obligation	5.15%	5.15%
Southern Power [Member] | 5.25% due 2043
Fixed stated interest rate of debt obligation	5.25%	5.25%
Southern Power [Member] | 3.25% due 2032-2034
Fixed stated interest rate of debt obligation	3.25%	3.25%