Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities:
Consolidated net income	$ 3,103,000	$ 4,744,000	$ 2,300,000
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	3,905,000	3,331,000	3,549,000
Deferred income taxes	(241,000)	611,000	89,000
Utilization of federal investment tax credits	341,000	757,000	5,000
Amortization of investment tax credits	(84,000)	(181,000)	(87,000)
Allowance for equity funds used during construction	(149,000)	(128,000)	(138,000)
Pension, postretirement, and other employee benefits	(259,000)	(204,000)	(103,000)
Pension and postretirement funding	(2,000)	(1,136,000)	(4,000)
Settlement of asset retirement obligations	(442,000)	(328,000)	(244,000)
Storm damage accruals	325,000	168,000	74,000
Stock based compensation expense	113,000	107,000	125,000
Estimated loss on Plant Vogtle Units 3 and 4	325,000	0	1,060,000
Impairment charges	206,000	168,000	210,000
Impairment charges	0	168,000	210,000
(Gain) loss on dispositions, net	(66,000)	(2,588,000)	(301,000)
Other, net	(74,000)	115,000	47,000
Changes in certain current assets and liabilities —
-Receivables	(222,000)	630,000	(426,000)
-Fossil fuel for generation	(29,000)	(120,000)	123,000
-Materials and supplies	(157,000)	(17,000)	(176,000)
-Other current assets	(132,000)	132,000	98,000
-Accounts payable	(27,000)	(693,000)	291,000
-Accrued taxes	242,000	117,000	267,000
-Retail fuel cost over recovery	96,000	62,000	36,000
-Customer refunds	(236,000)	126,000	67,000
-Other current liabilities	76,000	(73,000)	(4,000)
Net cash provided from operating activities	6,696,000	5,781,000	6,945,000
Investing Activities:
Business acquisitions, net of cash acquired	(81,000)	(50,000)	(65,000)
Property additions	(7,441,000)	(7,555,000)	(8,001,000)
Nuclear decommissioning trust fund purchases	(877,000)	(888,000)	(1,117,000)
Nuclear decommissioning trust fund sales	871,000	882,000	1,111,000
Proceeds from dispositions and asset sales	1,049,000	5,122,000	2,956,000
Cost of removal, net of salvage	(361,000)	(393,000)	(388,000)
Change in construction payables, net	37,000	(169,000)	50,000
Investments in unconsolidated subsidiaries	(80,000)	(148,000)	(114,000)
Payments pursuant to LTSAs	(211,000)	(234,000)	(186,000)
Other investing activities	64,000	41,000	(6,000)
Net cash used for investing activities	(7,030,000)	(3,392,000)	(5,760,000)
Financing Activities:
Increase (decrease) in notes payable, net		640,000
Increase (decrease) in notes payable, net	(1,096,000)		(774,000)
Proceeds —
Long-term debt	8,047,000	5,220,000	2,478,000
Common stock	74,000	844,000	1,090,000
Short-term borrowings	615,000	350,000	3,150,000
Redemptions and repurchases —
Long-term debt	(4,458,000)	(4,347,000)	(5,533,000)
Preferred and preference stock	0	0	(33,000)
Short-term borrowings	(840,000)	(1,850,000)	(1,900,000)
Distributions to noncontrolling interests	(271,000)	(256,000)	(153,000)
Capital contributions from noncontrolling interests	363,000	196,000	2,551,000
Payment of common stock dividends	(2,685,000)	(2,570,000)	(2,425,000)
Other financing activities	(325,000)	(157,000)	(264,000)
Net cash used for financing activities	(576,000)	(1,930,000)	(1,813,000)
Net Change in Cash, Cash Equivalents, and Restricted Cash	(910,000)	459,000	(628,000)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	1,978,000	1,519,000	2,147,000
Cash, Cash Equivalents, and Restricted Cash at End of Year	1,068,000	1,978,000	1,519,000
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	1,683,000	1,651,000	1,794,000
Income taxes (net of refunds)	64,000	276,000	172,000
Noncash transactions —
Accrued property additions at year-end	989,000	932,000	1,103,000
Alabama Power
Operating Activities:
Consolidated net income	1,165,000	1,085,000	945,000
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	963,000	951,000	917,000
Deferred income taxes	78,000	197,000	174,000
Allowance for equity funds used during construction	(46,000)	(52,000)	(62,000)
Pension and postretirement funding	(2,000)	(362,000)	(4,000)
Settlement of asset retirement obligations	(219,000)	(127,000)	(55,000)
Natural disaster reserve accruals	112,000	138,000	16,000
Other deferred charges – affiliated	0	(42,000)	0
Other, net	(38,000)	(91,000)	(17,000)
Changes in certain current assets and liabilities —
-Receivables	(49,000)	9,000	(149,000)
-Materials and supplies	(47,000)	23,000	(82,000)
-Other current assets	(66,000)	(89,000)	28,000
-Accounts payable	(90,000)	(41,000)	24,000
-Accrued taxes	84,000	49,000	10,000
-Retail fuel cost over recovery	(31,000)	47,000	0
-Customer refunds	(12,000)	30,000	114,000
-Other current liabilities	(28,000)	68,000	14,000
-Accrued compensation	(32,000)	(14,000)	8,000
Net cash provided from operating activities	1,742,000	1,779,000	1,881,000
Investing Activities:
Property additions	(1,970,000)	(1,757,000)	(2,158,000)
Nuclear decommissioning trust fund purchases	(268,000)	(261,000)	(279,000)
Nuclear decommissioning trust fund sales	267,000	260,000	278,000
Cost of removal, net of salvage	(98,000)	(103,000)	(130,000)
Change in construction payables, net	(34,000)	(71,000)	26,000
Other investing activities	(19,000)	(31,000)	(26,000)
Net cash used for investing activities	(2,122,000)	(1,963,000)	(2,289,000)
Proceeds —
Senior notes	600,000	600,000	500,000
Pollution control revenue bonds	87,000	0	120,000
Capital contributions from parent company	653,000	1,240,000	511,000
Redemptions and repurchases —
Senior notes	(250,000)	(200,000)	0
Pollution control revenue bonds	(87,000)	0	(120,000)
Payment of common stock dividends	(957,000)	(844,000)	(801,000)
Other financing activities	(30,000)	(31,000)	(33,000)
Net cash used for financing activities	16,000	765,000	177,000
Net Change in Cash, Cash Equivalents, and Restricted Cash	(364,000)	581,000	(231,000)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	894,000	313,000	544,000
Cash, Cash Equivalents, and Restricted Cash at End of Year	530,000	894,000	313,000
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	321,000	311,000	284,000
Income taxes (net of refunds)	187,000	26,000	106,000
Noncash transactions —
Accrued property additions at year-end	166,000	200,000	272,000
Georgia Power
Operating Activities:
Consolidated net income	1,575,000	1,720,000	793,000
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	1,607,000	1,193,000	1,142,000
Deferred income taxes	(273,000)	179,000	(260,000)
Allowance for equity funds used during construction	(91,000)	(68,000)	(69,000)
Pension, postretirement, and other employee benefits	(137,000)	(146,000)	(75,000)
Pension and postretirement funding	0	(200,000)	0
Settlement of asset retirement obligations	(185,000)	(151,000)	(116,000)
Retail fuel cost over recovery – long-term	(73,000)	73,000	0
Storm damage accruals	213,000	30,000	30,000
Other deferred charges – affiliated	0	(108,000)	0
Estimated loss on Plant Vogtle Units 3 and 4	325,000	0	1,060,000
Other, net	14,000	50,000	18,000
Changes in certain current assets and liabilities —
-Receivables	(114,000)	177,000	8,000
-Fossil fuel for generation	(6,000)	(41,000)	83,000
-Materials and supplies	(91,000)	(4,000)	(19,000)
-Other current assets	(48,000)	(15,000)	(24,000)
-Accounts payable	59,000	(92,000)	95,000
-Accrued taxes	55,000	58,000	58,000
-Retail fuel cost over recovery	113,000	0	0
-Customer refunds	(223,000)	116,000	(69,000)
-Other current liabilities	64,000	34,000	(38,000)
-Prepaid income taxes	0	102,000	152,000
Net cash provided from operating activities	2,784,000	2,907,000	2,769,000
Investing Activities:
Property additions	(3,445,000)	(3,510,000)	(3,116,000)
Nuclear decommissioning trust fund purchases	(609,000)	(628,000)	(839,000)
Nuclear decommissioning trust fund sales	604,000	622,000	833,000
Cost of removal, net of salvage	(143,000)	(186,000)	(107,000)
Payments pursuant to LTSAs	(86,000)	(81,000)	(54,000)
Change in construction payables, net of joint owner portion	16,000	(122,000)	68,000
Proceeds from dispositions and asset sales	153,000	14,000	138,000
Other investing activities	7,000	6,000	(32,000)
Net cash used for investing activities	(3,503,000)	(3,885,000)	(3,109,000)
Financing Activities:
Increase (decrease) in notes payable, net			294,000
Increase (decrease) in notes payable, net	(55,000)	(179,000)
Proceeds —
FFB loan	848,000	1,218,000	0
Short-term borrowings	250,000	250,000	0
Senior notes	1,500,000	750,000	0
Pollution control revenue bonds	53,000	584,000	108,000
Capital contributions from parent company	1,392,000	634,000	2,985,000
Redemptions and repurchases —
FFB loan	(73,000)	0	0
Short-term borrowings	(375,000)	0	(150,000)
Senior notes	(950,000)	(500,000)	(1,500,000)
Pollution control revenue bonds	(336,000)	(223,000)	(469,000)
Other long-term debt	0	0	(100,000)
Payment of common stock dividends	(1,542,000)	(1,576,000)	(1,396,000)
Premiums on redemption and repurchases of senior notes	0	0	(152,000)
Other financing activities	(36,000)	(40,000)	(20,000)
Net cash used for financing activities	676,000	918,000	(400,000)
Net Change in Cash, Cash Equivalents, and Restricted Cash	(43,000)	(60,000)	(740,000)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	52,000	112,000	852,000
Cash, Cash Equivalents, and Restricted Cash at End of Year	9,000	52,000	112,000
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	380,000	373,000	408,000
Income taxes (net of refunds)	373,000	110,000	300,000
Noncash transactions —
Accrued property additions at year-end	553,000	560,000	683,000
Mississippi Power
Operating Activities:
Consolidated net income	152,000	139,000	236,000
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	191,000	197,000	177,000
Deferred income taxes	(4,000)	37,000	475,000
Pension and postretirement funding	0	(54,000)	0
Settlement of asset retirement obligations	(22,000)	(35,000)	(35,000)
Other, net	(1,000)	35,000	51,000
Changes in certain current assets and liabilities —
-Receivables	(7,000)	6,000	(19,000)
-Other current assets	(28,000)	(8,000)	(10,000)
-Accounts payable	20,000	3,000	15,000
-Accrued taxes	10,000	11,000	(46,000)
-Other current liabilities	(15,000)	(20,000)	(42,000)
-Prepaid income taxes	(3,000)	12,000	(12,000)
-Over recovered regulatory clause revenues	5,000	16,000	14,000
Net cash provided from operating activities	298,000	339,000	804,000
Investing Activities:
Property additions	(274,000)	(202,000)	(188,000)
Payments pursuant to LTSAs	(28,000)	(23,000)	(29,000)
Other investing activities	(21,000)	(38,000)	(15,000)
Net cash used for investing activities	(323,000)	(263,000)	(232,000)
Financing Activities:
Increase (decrease) in notes payable, net	25,000
Increase (decrease) in notes payable, net		0	(4,000)
Proceeds —
Short-term borrowings	40,000	0	300,000
Senior notes	0	0	600,000
Pollution control revenue bonds	34,000	43,000	0
Other long-term debt	100,000	0	0
Capital contributions from parent company	85,000	51,000	15,000
Redemptions and repurchases —
Preferred and preference stock	0	0	(33,000)
Short-term borrowings	(40,000)	0	(300,000)
Senior notes	(275,000)	(25,000)	(155,000)
Pollution control revenue bonds	(41,000)	0	(43,000)
Other long-term debt	0	0	(900,000)
Return of capital to parent company	(74,000)	(150,000)	0
Payment of common stock dividends	(74,000)	0	0
Other financing activities	(2,000)	(2,000)	(7,000)
Net cash used for financing activities	(222,000)	(83,000)	(527,000)
Net Change in Cash, Cash Equivalents, and Restricted Cash	(247,000)	(7,000)	45,000
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	286,000	293,000	248,000
Cash, Cash Equivalents, and Restricted Cash at End of Year	39,000	286,000	293,000
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	63,000	71,000	80,000
Income taxes (net of refunds)	28,000	(27,000)	(525,000)
Noncash transactions —
Accrued property additions at year-end	34,000	35,000	35,000
Southern Power
Operating Activities:
Consolidated net income	207,000	329,000	246,000
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	519,000	505,000	524,000
Deferred income taxes	(25,000)	(74,000)	(244,000)
Utilization of federal investment tax credits	340,000	734,000	5,000
Amortization of investment tax credits	(59,000)	(151,000)	(58,000)
Pension and postretirement funding	0	(24,000)	0
Income taxes receivable, non-current	(20,000)	25,000	42,000
Impairment charges	0	3,000	156,000
(Gain) loss on dispositions, net	(39,000)	(24,000)	(3,000)
Other, net	(5,000)	(9,000)	(4,000)
Changes in certain current assets and liabilities —
-Receivables	(4,000)	72,000	(20,000)
-Other current assets	(30,000)	(8,000)	(26,000)
-Accrued taxes	11,000	6,000	7,000
-Other current liabilities	(14,000)	(38,000)	(19,000)
-Prepaid income taxes	20,000	39,000	25,000
Net cash provided from operating activities	901,000	1,385,000	631,000
Investing Activities:
Business acquisitions, net of cash acquired	(81,000)	(50,000)	(65,000)
Property additions	(223,000)	(489,000)	(315,000)
Proceeds from dispositions and asset sales	666,000	572,000	203,000
Investments in unconsolidated subsidiaries	0	(116,000)	0
Payments pursuant to LTSAs	(76,000)	(104,000)	(75,000)
Other investing activities	88,000	20,000	25,000
Net cash used for investing activities	374,000	(167,000)	(227,000)
Financing Activities:
Increase (decrease) in notes payable, net		449,000
Increase (decrease) in notes payable, net	(274,000)		(105,000)
Proceeds —
Short-term borrowings	0	100,000	200,000
Capital contributions from parent company	6,000	64,000	2,000
Redemptions and repurchases —
Short-term borrowings	(100,000)	(100,000)	(100,000)
Senior notes	(825,000)	(600,000)	(350,000)
Other long-term debt	0	0	(420,000)
Return of capital to parent company	0	(755,000)	(1,650,000)
Distributions to noncontrolling interests	(271,000)	(256,000)	(153,000)
Capital contributions from noncontrolling interests	363,000	196,000	2,551,000
Purchase of membership interests from noncontrolling interests	(60,000)	0	0
Payment of common stock dividends	(201,000)	(206,000)	(312,000)
Other financing activities	(10,000)	(12,000)	(26,000)
Net cash used for financing activities	(1,372,000)	(1,120,000)	(363,000)
Net Change in Cash, Cash Equivalents, and Restricted Cash	(97,000)	98,000	41,000
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	279,000	181,000	140,000
Cash, Cash Equivalents, and Restricted Cash at End of Year	182,000	279,000	181,000
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	147,000	167,000	173,000
Income taxes (net of refunds)	(283,000)	(664,000)	79,000
Noncash transactions —
Accrued property additions at year-end	89,000	57,000	31,000
Southern Company Gas
Operating Activities:
Consolidated net income	590,000	585,000	372,000
Adjustments to reconcile consolidated net income to net cash provided from operating activities —
Depreciation and amortization, total	500,000	487,000	500,000
Deferred income taxes	56,000	213,000	(1,000)
Pension and postretirement funding	0	(145,000)	0
Impairment charges	0	115,000	42,000
(Gain) loss on dispositions, net	(22,000)	0	(291,000)
Mark-to-market adjustments	61,000	(56,000)	(19,000)
Other, net	(29,000)	(55,000)	(24,000)
Changes in certain current assets and liabilities —
-Receivables	(93,000)	467,000	(218,000)
-Natural gas for sale	18,000	44,000	49,000
-Other current assets	(10,000)	31,000	4,000
-Accounts payable	103,000	(520,000)	372,000
-Accrued taxes	13,000	(69,000)	10,000
-Other current liabilities	(6,000)	(71,000)	(22,000)
-Prepaid income taxes	19,000	40,000	(42,000)
-Accrued compensation	7,000	1,000	32,000
Net cash provided from operating activities	1,207,000	1,067,000	764,000
Investing Activities:
Property additions	(1,471,000)	(1,408,000)	(1,388,000)
Proceeds from dispositions and asset sales	211,000	32,000	2,609,000
Cost of removal, net of salvage	(100,000)	(82,000)	(96,000)
Change in construction payables, net	20,000	24,000	(37,000)
Investments in unconsolidated subsidiaries	(79,000)	(31,000)	(110,000)
Returned investment in unconsolidated subsidiaries	13,000	67,000	20,000
Other investing activities	(11,000)	12,000	0
Net cash used for investing activities	(1,417,000)	(1,386,000)	998,000
Financing Activities:
Increase (decrease) in notes payable, net	(326,000)	0	(868,000)
Proceeds —
First mortgage bonds	325,000	300,000	300,000
Senior notes	500,000	0	0
Capital contributions from parent company	216,000	821,000	24,000
Redemptions and repurchases —
Gas facility revenue bonds	0	0	(200,000)
Senior notes	0	(300,000)	(155,000)
First mortgage bonds	0	(50,000)	0
Return of capital to parent company	0	0	(400,000)
Payment of common stock dividends	(533,000)	(471,000)	(468,000)
Other financing activities	(2,000)	(2,000)	(3,000)
Net cash used for financing activities	180,000	298,000	(1,770,000)
Net Change in Cash, Cash Equivalents, and Restricted Cash	(30,000)	(21,000)	(8,000)
Cash, Cash Equivalents, and Restricted Cash at Beginning of Year	49,000	70,000	78,000
Cash, Cash Equivalents, and Restricted Cash at End of Year	19,000	49,000	70,000
Supplemental Cash Flow Information:
Interest, net of amounts capitalized	232,000	251,000	249,000
Income taxes (net of refunds)	25,000	(41,000)	524,000
Noncash transactions —
Accrued property additions at year-end	$ 142,000	$ 122,000	$ 97,000