Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Amortization expense on other intangible assets	$ 62	$ 12
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	$ 22	$ 12
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%
Southern Power [Member] | 1.50% due 2018 [Member]
Fixed stated interest rate of debt obligation	1.50%	1.50%
Southern Power [Member] | Senior Notes Due Two Thousand Nineteen [Member]
Fixed stated interest rate of debt obligation	1.95%	1.95%
Southern Power [Member] | 2.375% due 2020 [Member]
Fixed stated interest rate of debt obligation	2.375%	2.375%
Southern Power [Member] | Senior Notes Due Two Thousand Twenty One [Member]
Fixed stated interest rate of debt obligation	2.50%	2.50%
Southern Power [Member] | Other Long Term Notes Due Two Thousand eighteen [Member]
Fixed stated interest rate of debt obligation	1.88%	1.88%
Southern Power [Member] | Other Long Term Notes Due Two Thousand Thirty Two to Two Thousand Thirty Six [Member]
Fixed stated interest rate of debt obligation	3.75%	3.75%
Minimum [Member] | Southern Power [Member] | Senior Notes Due Two Thousand Twenty Two Through Two Thousand Forty Six [Member]
Fixed stated interest rate of debt obligation	1.00%	1.00%
Maximum [Member] | Southern Power [Member] | Senior Notes Due Two Thousand Twenty Two Through Two Thousand Forty Six [Member]
Fixed stated interest rate of debt obligation	6.375%	6.375%
Successor [Member] | Southern Company Gas [Member]
Amortization expense on other intangible assets	$ 34
Common stock, par value per share (in dollars per share)	$ 0.01
Common stock, shares authorized	100,000,000
Common stock, shares outstanding	100
Predecessor [Member] | Southern Company Gas [Member]
Amortization expense on other intangible assets		$ 68
Common stock, par value per share (in dollars per share)		$ 5
Common stock, shares authorized		750,000,000
Common stock, shares outstanding		120,400,000