Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net cash paid for capitalized interest	$ 25	$ 30
Alabama Power [Member]
Net cash paid for capitalized interest	3	4
Georgia Power [Member]
Net cash paid for capitalized interest	5	5
Gulf Power [Member]
Net cash paid for capitalized interest	0	0
Mississippi Power [Member]
Interest paid	25	22
Net cash paid for capitalized interest	12	10
Southern Power [Member]
Net cash paid for capitalized interest	2	10
Southern Company Gas [Member]
Net cash paid for capitalized interest	$ 3
Predecessor [Member] | Southern Company Gas [Member]
Net cash paid for capitalized interest		$ 1