Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net cash paid for capitalized interest	$ 74	$ 72	$ 89
Alabama Power
Net cash paid for capitalized interest	19	22	15
Georgia Power
Net cash paid for capitalized interest	35	26	23
Mississippi Power
Net cash paid for capitalized interest	(1)	0	29
Southern Power
Net cash paid for capitalized interest	15	17	11
Southern Company Gas
Net cash paid for capitalized interest	$ 6	$ 7	$ 11