Consolidated Statements of Income - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Revenues:
Total operating revenues	$ 21,419,000,000	$ 23,495,000,000	$ 23,031,000,000
Operating Expenses:
Other operations and maintenance	5,600,000,000	5,889,000,000	5,739,000,000
Depreciation and amortization	3,038,000,000	3,131,000,000	3,010,000,000
Taxes other than income taxes	1,230,000,000	1,315,000,000	1,250,000,000
Estimated loss on plants	24,000,000	1,097,000,000	3,362,000,000
Impairment charges	168,000,000	210,000,000	0
(Gain) loss on dispositions, net	(2,569,000,000)	(291,000,000)	(40,000,000)
Gain on dispositions, net	2,588,000,000	301,000,000	42,000,000
Depreciation and amortization	3,331,000,000	3,549,000,000	3,457,000,000
Total operating expenses	13,683,000,000	19,304,000,000	20,698,000,000
Operating Income	7,736,000,000	4,191,000,000	2,333,000,000
Other Income and (Expense):
Allowance for equity funds used during construction	128,000,000	138,000,000	160,000,000
Earnings from equity method investments	162,000,000	148,000,000	106,000,000
Interest expense, net of amounts capitalized	(1,736,000,000)	(1,842,000,000)	(1,694,000,000)
Other income (expense), net	252,000,000	114,000,000	163,000,000
Total other income and (expense)	(1,194,000,000)	(1,442,000,000)	(1,265,000,000)
Earnings Before Income Taxes	6,542,000,000	2,749,000,000	1,068,000,000
Income taxes	1,798,000,000	449,000,000	142,000,000
Net Income	4,744,000,000	2,300,000,000	926,000,000
Dividends on preferred and preference stock of subsidiaries	15,000,000	16,000,000	38,000,000
Net income (loss) attributable to noncontrolling interests	(10,000,000)	58,000,000	46,000,000
Net Income (Loss)	$ 4,739,000,000	$ 2,226,000,000	$ 842,000,000
Earnings per share —
Basic (in dollars per share)	$ 4.53	$ 2.18	$ 0.84
Diluted (in dollars per share)	$ 4.50	$ 2.17	$ 0.84
Average number of shares of common stock outstanding — (in millions)
Basic (in shares)	1,046	1,020	1,000
Diluted (in shares)	1,054	1,025	1,008
Retail electric revenues
Operating Revenues:
Total operating revenues	$ 14,084,000,000	$ 15,222,000,000	$ 15,330,000,000
Wholesale revenues, non-affiliates
Operating Revenues:
Total operating revenues	2,152,000,000	2,516,000,000	2,426,000,000
Other electric revenues
Operating Revenues:
Total operating revenues	636,000,000	664,000,000	681,000,000
Fuel
Operating Expenses:
Cost of revenue	3,622,000,000	4,637,000,000	4,400,000,000
Purchased power
Operating Expenses:
Cost of revenue	816,000,000	971,000,000	863,000,000
Natural gas revenues
Operating Revenues:
Total operating revenues	3,792,000,000	3,854,000,000	3,791,000,000
Operating Expenses:
Cost of revenue	1,319,000,000	1,539,000,000	1,601,000,000
Other revenues
Operating Revenues:
Total operating revenues	755,000,000	1,239,000,000	803,000,000
Operating Expenses:
Cost of revenue	435,000,000	806,000,000	513,000,000
Alabama Power
Operating Revenues:
Total operating revenues	6,125,000,000	6,032,000,000	6,039,000,000
Operating Expenses:
Other operations and maintenance	1,821,000,000	1,669,000,000	1,709,000,000
Depreciation and amortization	793,000,000	764,000,000	736,000,000
Taxes other than income taxes	403,000,000	389,000,000	384,000,000
Purchased power, non-affiliates	203,000,000	216,000,000	170,000,000
Purchased power, affiliates	200,000,000	216,000,000	158,000,000
Depreciation and amortization	951,000,000	917,000,000	888,000,000
Total operating expenses	4,532,000,000	4,555,000,000	4,382,000,000
Operating Income	1,593,000,000	1,477,000,000	1,657,000,000
Other Income and (Expense):
Allowance for equity funds used during construction	52,000,000	62,000,000	39,000,000
Interest expense, net of amounts capitalized	(336,000,000)	(323,000,000)	(305,000,000)
Other income (expense), net	46,000,000	20,000,000	43,000,000
Total other income and (expense)	(238,000,000)	(241,000,000)	(223,000,000)
Earnings Before Income Taxes	1,355,000,000	1,236,000,000	1,434,000,000
Income taxes	270,000,000	291,000,000	568,000,000
Net Income	1,085,000,000	945,000,000	866,000,000
Dividends on preferred and preference stock of subsidiaries	15,000,000	15,000,000	18,000,000
Net Income (Loss)	1,070,000,000	930,000,000	848,000,000
Alabama Power | Retail electric revenues
Operating Revenues:
Total operating revenues	5,501,000,000	5,367,000,000	5,458,000,000
Alabama Power | Wholesale revenues, non-affiliates
Operating Revenues:
Total operating revenues	258,000,000	279,000,000	276,000,000
Alabama Power | Wholesale revenues, affiliates
Operating Revenues:
Total operating revenues	81,000,000	119,000,000	97,000,000
Alabama Power | Fuel
Operating Expenses:
Cost of revenue	1,112,000,000	1,301,000,000	1,225,000,000
Alabama Power | Other revenues
Operating Revenues:
Total operating revenues	285,000,000	267,000,000	208,000,000
Georgia Power
Operating Revenues:
Total operating revenues	8,408,000,000	8,420,000,000	8,310,000,000
Operating Expenses:
Other operations and maintenance	1,972,000,000	1,860,000,000	1,724,000,000
Depreciation and amortization	981,000,000	923,000,000	895,000,000
Taxes other than income taxes	454,000,000	437,000,000	409,000,000
Estimated loss on plants	0	1,060,000,000	0
Purchased power, non-affiliates	521,000,000	430,000,000	416,000,000
Purchased power, affiliates	575,000,000	723,000,000	622,000,000
Depreciation and amortization	1,193,000,000	1,142,000,000	1,100,000,000
Total operating expenses	5,947,000,000	7,131,000,000	5,737,000,000
Operating Income	2,461,000,000	1,289,000,000	2,573,000,000
Other Income and (Expense):
Interest expense, net of amounts capitalized	(409,000,000)	(397,000,000)	(419,000,000)
Other income (expense), net	140,000,000	115,000,000	104,000,000
Total other income and (expense)	(269,000,000)	(282,000,000)	(315,000,000)
Earnings Before Income Taxes	2,192,000,000	1,007,000,000	2,258,000,000
Income taxes	472,000,000	214,000,000	830,000,000
Net Income	1,720,000,000	793,000,000	1,428,000,000
Dividends on preferred and preference stock of subsidiaries	0	0	14,000,000
Net Income (Loss)	1,720,000,000	793,000,000	1,414,000,000
Georgia Power | Retail electric revenues
Operating Revenues:
Total operating revenues	7,707,000,000	7,752,000,000	7,738,000,000
Georgia Power | Wholesale revenues, non-affiliates
Operating Revenues:
Total operating revenues	129,000,000	163,000,000	163,000,000
Georgia Power | Wholesale revenues, affiliates
Operating Revenues:
Total operating revenues	11,000,000	24,000,000	26,000,000
Georgia Power | Fuel
Operating Expenses:
Cost of revenue	1,444,000,000	1,698,000,000	1,671,000,000
Georgia Power | Other revenues
Operating Revenues:
Total operating revenues	561,000,000	481,000,000	383,000,000
Mississippi Power
Operating Revenues:
Total operating revenues	1,264,000,000	1,265,000,000	1,187,000,000
Operating Expenses:
Other operations and maintenance	283,000,000	313,000,000	291,000,000
Depreciation and amortization	192,000,000	169,000,000	161,000,000
Taxes other than income taxes	113,000,000	107,000,000	104,000,000
Estimated loss on plants	24,000,000	37,000,000	3,362,000,000
Purchased power, affiliates	20,000,000	41,000,000	25,000,000
Depreciation and amortization	197,000,000	177,000,000	198,000,000
Total operating expenses	1,039,000,000	1,072,000,000	4,338,000,000
Operating Income	225,000,000	193,000,000	(3,151,000,000)
Other Income and (Expense):
Allowance for equity funds used during construction	1,000,000	0	72,000,000
Interest expense, net of amounts capitalized	(69,000,000)	(76,000,000)	(42,000,000)
Other income (expense), net	12,000,000	17,000,000	1,000,000
Total other income and (expense)	(56,000,000)	(59,000,000)	31,000,000
Earnings Before Income Taxes	169,000,000	134,000,000	(3,120,000,000)
Income taxes	30,000,000	(102,000,000)	(532,000,000)
Net Income	139,000,000	236,000,000	(2,588,000,000)
Dividends on preferred and preference stock of subsidiaries	0	1,000,000	2,000,000
Net Income (Loss)	139,000,000	235,000,000	(2,590,000,000)
Mississippi Power | Retail electric revenues
Operating Revenues:
Total operating revenues	877,000,000	889,000,000	854,000,000
Mississippi Power | Wholesale revenues, non-affiliates
Operating Revenues:
Total operating revenues	237,000,000	263,000,000	259,000,000
Mississippi Power | Wholesale revenues, affiliates
Operating Revenues:
Total operating revenues	132,000,000	91,000,000	56,000,000
Mississippi Power | Fuel
Operating Expenses:
Cost of revenue	407,000,000	405,000,000	395,000,000
Mississippi Power | Other revenues
Operating Revenues:
Total operating revenues	18,000,000	22,000,000	18,000,000
Southern Power
Operating Revenues:
Total operating revenues	1,938,000,000	2,205,000,000	2,075,000,000
Operating Expenses:
Other operations and maintenance	359,000,000	395,000,000	386,000,000
Depreciation and amortization	479,000,000	493,000,000	503,000,000
Taxes other than income taxes	40,000,000	46,000,000	48,000,000
Impairment charges	3,000,000	156,000,000	0
Gain on dispositions, net	(23,000,000)	(2,000,000)	0
Purchased power, non-affiliates	108,000,000	176,000,000	149,000,000
Depreciation and amortization	505,000,000	524,000,000	536,000,000
Total operating expenses	1,543,000,000	1,963,000,000	1,707,000,000
Operating Income	395,000,000	242,000,000	368,000,000
Other Income and (Expense):
Interest expense, net of amounts capitalized	(169,000,000)	(183,000,000)	(191,000,000)
Other income (expense), net	47,000,000	23,000,000	1,000,000
Total other income and (expense)	(122,000,000)	(160,000,000)	(190,000,000)
Earnings Before Income Taxes	273,000,000	82,000,000	178,000,000
Income taxes	(56,000,000)	(164,000,000)	(939,000,000)
Net Income	329,000,000	246,000,000	1,117,000,000
Net income (loss) attributable to noncontrolling interests	(10,000,000)	59,000,000	46,000,000
Net Income (Loss)	339,000,000	187,000,000	1,071,000,000
Southern Power | Wholesale revenues, non-affiliates
Operating Revenues:
Total operating revenues	1,528,000,000	1,757,000,000	1,671,000,000
Southern Power | Wholesale revenues, affiliates
Operating Revenues:
Total operating revenues	398,000,000	435,000,000	392,000,000
Southern Power | Fuel
Operating Expenses:
Cost of revenue	577,000,000	699,000,000	621,000,000
Southern Power | Other revenues
Operating Revenues:
Total operating revenues	12,000,000	13,000,000	12,000,000
Southern Company Gas
Operating Revenues:
Total operating revenues	3,792,000,000	3,909,000,000	3,920,000,000
Operating Expenses:
Other operations and maintenance	888,000,000	981,000,000	945,000,000
Taxes other than income taxes	213,000,000	211,000,000	184,000,000
Impairment charges	115,000,000	42,000,000	0
(Gain) loss on dispositions, net	0	(291,000,000)	0
Gain on dispositions, net	0	291,000,000	0
Depreciation and amortization	487,000,000	500,000,000	501,000,000
Total operating expenses	3,022,000,000	2,994,000,000	3,260,000,000
Operating Income	770,000,000	915,000,000	660,000,000
Other Income and (Expense):
Earnings from equity method investments	157,000,000	148,000,000	106,000,000
Interest expense, net of amounts capitalized	(232,000,000)	(228,000,000)	(200,000,000)
Other income (expense), net	20,000,000	1,000,000	44,000,000
Total other income and (expense)	(55,000,000)	(79,000,000)	(50,000,000)
Earnings Before Income Taxes	715,000,000	836,000,000	610,000,000
Income taxes	130,000,000	464,000,000	367,000,000
Net Income	585,000,000	372,000,000	243,000,000
Net Income (Loss)	585,000,000	372,000,000	243,000,000
Southern Company Gas | Natural gas revenues
Operating Revenues:
Total operating revenues	3,793,000,000	3,874,000,000	3,787,000,000
Operating Expenses:
Cost of revenue	1,319,000,000	1,539,000,000	1,601,000,000
Southern Company Gas | Alternative revenue programs
Operating Revenues:
Total operating revenues	(1,000,000)	(20,000,000)	4,000,000
Southern Company Gas | Other revenues
Operating Revenues:
Total operating revenues	0	55,000,000	129,000,000
Operating Expenses:
Cost of revenue	$ 0	$ 12,000,000	$ 29,000,000