Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net cash paid for capitalized interest		$ 125	$ 124	$ 111
Alabama Power [Member]
Net cash paid for capitalized interest		11	22	18
Georgia Power [Member]
Net cash paid for capitalized interest		20	16	18
Gulf Power [Member]
Net cash paid for capitalized interest		0	6	5
Mississippi Power [Member]
Net cash paid for capitalized interest		49	66	69
Southern Power [Member]
Net cash paid for capitalized interest		$ 44	$ 14	$ 0
Southern Company Gas [Member] | Successor [Member] | Southstar [Member]
Ownership percentage of noncontrolling interest	15.00%