Georgia Power (GPJA) 10-Q 4 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	9 Months Ended
	Sep. 30, 2016shares
Document Information [Line Items]
Entity Registrant Name	SOUTHERN CO
Entity Central Index Key	92,122
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	979,999,480
Alabama Power [Member]
Document Information [Line Items]
Entity Registrant Name	ALABAMA POWER CO
Entity Central Index Key	3,153
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	30,537,500
Georgia Power [Member]
Document Information [Line Items]
Entity Registrant Name	GEORGIA POWER CO
Entity Central Index Key	41,091
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	9,261,500
Gulf Power [Member]
Document Information [Line Items]
Entity Registrant Name	GULF POWER CO
Entity Central Index Key	44,545
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	5,642,717
Mississippi Power [Member]
Document Information [Line Items]
Entity Registrant Name	MISSISSIPPI POWER CO
Entity Central Index Key	66,904
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	1,121,000
Southern Power [Member]
Document Information [Line Items]
Entity Registrant Name	SOUTHERN POWER CO
Entity Central Index Key	1,160,661
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	1,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating Revenues:
Retail revenues	$ 4,808	$ 4,701	$ 11,932	$ 11,958
Wholesale revenues	613	520	1,455	1,435
Other electric revenues	181	169	529	494
Natural gas revenues	518	0	518	0
Other revenues	144	11	281	34
Total operating revenues	6,264	5,401	14,715	13,921
Operating Expenses:
Fuel	1,400	1,520	3,334	3,932
Purchased power	227	193	581	507
Cost of natural gas	133	0	133	0
Cost of sales	84	0	161	0
Other operations and maintenance	1,411	1,097	3,616	3,320
Depreciation and amortization	695	528	1,805	1,515
Taxes other than income taxes	309	264	821	761
Estimated loss on Kemper IGCC	88	150	222	182
Total operating expenses	4,347	3,752	10,673	10,217
Operating Income (Loss)	1,917	1,649	4,042	3,704
Other Income and (Expense):
Allowance for equity funds used during construction	52	60	150	163
Interest expense, net of amounts capitalized	(374)	(218)	(913)	(612)
Other income (expense), net	21	(21)	(38)	(41)
Total other income and (expense)	(301)	(179)	(801)	(490)
Earnings (Loss) Before Income Taxes	1,616	1,470	3,241	3,214
Income taxes (benefit)	448	500	942	1,076
Net Income (Loss)	1,168	970	2,299	2,138
Dividends on preferred and preference stock of subsidiaries	11	11	34	42
Less: Net income attributable to noncontrolling interests	27	0	39	0
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	$ 1,130	$ 959	$ 2,226	$ 2,096
Earnings per share (EPS) -
Basic EPS (in dollars per share)	$ 1.17	$ 1.05	$ 2.37	$ 2.30
Diluted EPS (in dollars per share)	$ 1.16	$ 1.05	$ 2.36	$ 2.30
Average number of shares of common stock outstanding (in millions)
Basic (in shares)	968	910	940	910
Diluted (in shares)	975	912	945	913
Cash dividends paid per share of common stock (in dollars per share)	$ 0.56	$ 0.5425	$ 1.6625	$ 1.61
Alabama Power [Member]
Operating Revenues:
Retail revenues	$ 1,629	$ 1,558	$ 4,139	$ 4,151
Wholesale revenues, non-affiliates	82	65	211	188
Wholesale revenues, affiliates	18	20	49	55
Other revenues	56	52	162	157
Total operating revenues	1,785	1,695	4,561	4,551
Operating Expenses:
Fuel	410	408	973	1,061
Purchased power, non-affiliates	63	56	139	142
Purchased power, affiliates	41	51	129	153
Other operations and maintenance	348	371	1,097	1,140
Depreciation and amortization	177	163	524	481
Taxes other than income taxes	96	91	286	275
Total operating expenses	1,135	1,140	3,148	3,252
Operating Income (Loss)	650	555	1,413	1,299
Other Income and (Expense):
Allowance for equity funds used during construction	7	14	23	43
Interest expense, net of amounts capitalized	(77)	(71)	(224)	(205)
Other income (expense), net	(5)	(7)	(16)	(24)
Total other income and (expense)	(75)	(64)	(217)	(186)
Earnings (Loss) Before Income Taxes	575	491	1,196	1,113
Income taxes (benefit)	221	192	466	427
Net Income (Loss)	354	299	730	686
Dividends on preferred and preference stock of subsidiaries	4	4	13	21
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	350	295	717	665
Georgia Power [Member]
Operating Revenues:
Retail revenues	2,540	2,537	6,164	6,223
Wholesale revenues, non-affiliates	49	55	131	173
Wholesale revenues, affiliates	9	5	24	18
Other revenues	100	94	302	271
Total operating revenues	2,698	2,691	6,621	6,685
Operating Expenses:
Fuel	575	706	1,390	1,735
Purchased power, non-affiliates	102	90	277	227
Purchased power, affiliates	142	148	392	411
Other operations and maintenance	496	462	1,393	1,405
Depreciation and amortization	215	214	639	633
Taxes other than income taxes	114	107	311	302
Total operating expenses	1,644	1,727	4,402	4,713
Operating Income (Loss)	1,054	964	2,219	1,972
Other Income and (Expense):
Allowance for equity funds used during construction			36	24
Interest expense, net of amounts capitalized	(98)	(90)	(290)	(272)
Other income (expense), net	11	18	35	34
Total other income and (expense)	(87)	(72)	(255)	(238)
Earnings (Loss) Before Income Taxes	967	892	1,964	1,734
Income taxes (benefit)	365	337	737	657
Net Income (Loss)	602	555	1,227	1,077
Dividends on preferred and preference stock of subsidiaries	4	4	13	13
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	598	551	1,214	1,064
Gulf Power [Member]
Operating Revenues:
Retail revenues	377	363	978	983
Wholesale revenues, non-affiliates	17	30	48	82
Wholesale revenues, affiliates	23	17	59	52
Other revenues	19	19	51	53
Total operating revenues	436	429	1,136	1,170
Operating Expenses:
Fuel	141	143	342	375
Purchased power, non-affiliates	33	26	95	76
Purchased power, affiliates	3	4	9	22
Other operations and maintenance	86	90	239	274
Depreciation and amortization	49	40	129	100
Taxes other than income taxes	34	35	93	91
Total operating expenses	346	338	907	938
Operating Income (Loss)	90	91	229	232
Other Income and (Expense):
Interest expense, net of amounts capitalized	(11)	(12)	(36)	(38)
Other income (expense), net	(2)	2	(4)	8
Total other income and (expense)	(13)	(10)	(40)	(30)
Earnings (Loss) Before Income Taxes	77	81	189	202
Income taxes (benefit)	30	31	74	75
Net Income (Loss)	47	50	115	127
Dividends on preferred and preference stock of subsidiaries	2	2	7	7
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	45	48	108	120
Mississippi Power [Member]
Operating Revenues:
Retail revenues	263	244	652	601
Wholesale revenues, non-affiliates	78	76	198	216
Wholesale revenues, affiliates	7	18	23	63
Other revenues	4	3	12	13
Total operating revenues	352	341	885	893
Operating Expenses:
Fuel	112	130	268	359
Purchased power, non-affiliates	3	1	4	5
Purchased power, affiliates	5	1	14	6
Other operations and maintenance	74	63	211	206
Depreciation and amortization	30	38	114	95
Taxes other than income taxes	31	24	81	71
Estimated loss on Kemper IGCC	88	150	222	182
Total operating expenses	343	407	914	924
Operating Income (Loss)	9	(66)	(29)	(31)
Other Income and (Expense):
Allowance for equity funds used during construction	31	29	90	82
Interest expense, net of amounts capitalized	(15)	(13)	(46)	6
Other income (expense), net	(1)	(2)	(4)	(5)
Total other income and (expense)	15	14	40	83
Earnings (Loss) Before Income Taxes	24	(52)	11	52
Income taxes (benefit)	(2)	(31)	(29)	(11)
Net Income (Loss)	26	(21)	40	63
Dividends on preferred and preference stock of subsidiaries	0	0	1	1
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	26	(21)	39	62
Southern Power [Member]
Operating Revenues:
Wholesale revenues, non-affiliates	387	295	866	776
Wholesale revenues, affiliates	110	104	313	303
Other revenues	3	2	10	7
Total operating revenues	500	401	1,189	1,086
Operating Expenses:
Fuel	154	118	341	361
Purchased power, non-affiliates	25	17	60	52
Purchased power, affiliates	8	5	16	18
Other operations and maintenance	81	62	246	184
Depreciation and amortization	93	64	247	183
Taxes other than income taxes	5	6	17	17
Total operating expenses	366	272	927	815
Operating Income (Loss)	134	129	262	271
Other Income and (Expense):
Interest expense, net of amounts capitalized	(35)	(18)	(78)	(62)
Other income (expense), net	2	1	3	1
Total other income and (expense)	(33)	(17)	(75)	(61)
Earnings (Loss) Before Income Taxes	101	112	187	210
Income taxes (benefit)	(102)	1	(167)	14
Net Income (Loss)	203	111	354	196
Less: Net income attributable to noncontrolling interests	27	9	39	15
Net income attributable to Southern Power Company	$ 176	$ 102	$ 315	$ 181

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Income (loss)	$ 1,168	$ 970	$ 2,299	$ 2,138
Qualifying hedges:
Changes in fair value, net of tax	19	(18)	(118)	(16)
Reclassification adjustment for amounts included in net income, net of tax	2	1	20	4
Pension and other postretirement benefit plans:
Reclassification adjustment for amounts included in net income, net of tax	1	2	3	5
Total other comprehensive income (loss)	22	(15)	(95)	(7)
Dividends on preferred and preference stock of subsidiaries	11	11	34	42
Comprehensive income attributable to noncontrolling interests	27	0	39	0
Comprehensive Income (Loss)	1,152	944	2,131	2,089
Alabama Power [Member]
Net Income (loss)	354	299	730	686
Qualifying hedges:
Changes in fair value, net of tax	0	(6)	(2)	(6)
Reclassification adjustment for amounts included in net income, net of tax	1	0	3	1
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)	1	(6)	1	(5)
Dividends on preferred and preference stock of subsidiaries	4	4	13	21
Comprehensive Income (Loss)	355	293	731	681
Georgia Power [Member]
Net Income (loss)	602	555	1,227	1,077
Qualifying hedges:
Changes in fair value, net of tax	0	(11)	0	(10)
Reclassification adjustment for amounts included in net income, net of tax	1	1	2	2
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)	1	(10)	2	(8)
Dividends on preferred and preference stock of subsidiaries	4	4	13	13
Comprehensive Income (Loss)	603	545	1,229	1,069
Gulf Power [Member]
Net Income (loss)	47	50	115	127
Qualifying hedges:
Changes in fair value, net of tax	0	0	(4)	0
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)	0	0	(4)	0
Dividends on preferred and preference stock of subsidiaries	2	2	7	7
Comprehensive Income (Loss)	47	50	111	127
Mississippi Power [Member]
Net Income (loss)	26	(21)	40	63
Qualifying hedges:
Changes in fair value, net of tax	0	0	(1)	0
Reclassification adjustment for amounts included in net income, net of tax	0	0	1	1
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)	0	0	0	1
Dividends on preferred and preference stock of subsidiaries	0	0	1	1
Comprehensive Income (Loss)	26	(21)	40	64
Southern Power [Member]
Net Income (loss)	203	111	354	196
Qualifying hedges:
Changes in fair value, net of tax	23	0	(1)	0
Reclassification adjustment for amounts included in net income, net of tax	(1)	0	13	0
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)	22	0	12	0
Comprehensive income attributable to noncontrolling interests	27	9	39	15
Comprehensive Income (Loss)	$ 198	$ 102	$ 327	$ 181

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Changes in fair value, tax	$ 12	$ (11)	$ (74)	$ (10)
Reclassification adjustment for qualified hedges, tax	2	1	13	3
Reclassification adjustment for pension and other post retirement benefit plans, tax	1	1	2	3
Alabama Power [Member]
Changes in fair value, tax	0	(4)	(1)	(4)
Reclassification adjustment for qualified hedges, tax	1	0	2	1
Georgia Power [Member]
Changes in fair value, tax	0	(7)	0	(7)
Reclassification adjustment for qualified hedges, tax	0	0	1	1
Gulf Power [Member]
Changes in fair value, tax	0	0	(3)	0
Mississippi Power [Member]
Changes in fair value, tax	0	0	0	0
Reclassification adjustment for qualified hedges, tax	0	0	0	0
Southern Power [Member]
Changes in fair value, tax	14	0	(1)	0
Reclassification adjustment for qualified hedges, tax	$ (1)	$ 0	$ 7	$ 0

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities:
Net income (loss)	$ 2,299,000,000	$ 2,138,000,000
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	2,109,000,000	1,787,000,000
Deferred income taxes	(22,000,000)	821,000,000
Investment tax credits	0	319,000,000
Allowance for equity funds used during construction	(150,000,000)	(163,000,000)
Pension, postretirement, and other employee benefits	(158,000,000)	79,000,000
Settlement of asset retirement obligations	(117,000,000)	(20,000,000)
Stock based compensation expense	87,000,000	77,000,000
Hedge settlements	(236,000,000)	(4,000,000)
Estimated loss on Kemper IGCC	222,000,000	182,000,000
Income taxes receivable, non-current	0	(444,000,000)
Other, net	(98,000,000)	(48,000,000)
Changes in certain current assets and liabilities —
-Receivables	(458,000,000)	(118,000,000)
-Fossil fuel stock	204,000,000	239,000,000
-Natural gas for sale	(222,000,000)	0
-Other current assets	(111,000,000)	(40,000,000)
-Accounts payable	(9,000,000)	(266,000,000)
-Accrued taxes	1,062,000,000	408,000,000
-Accrued compensation	(122,000,000)	(129,000,000)
-Mirror CWIP	0	99,000,000
-Other current liabilities	(18,000,000)	171,000,000
Net cash provided from (used for) operating activities	4,262,000,000	5,088,000,000
Investing Activities:
Business acquisitions, net of cash acquired	(9,513,000,000)	(1,128,000,000)
Property additions	(5,252,000,000)	(3,490,000,000)
Investment in restricted cash	(750,000,000)	0
Distributions of restricted cash	746,000,000	0
Nuclear decommissioning trust fund purchases	(838,000,000)	(1,164,000,000)
Nuclear decommissioning trust fund sales	832,000,000	1,159,000,000
Cost of removal, net of salvage	(155,000,000)	(118,000,000)
Change in construction payables	(259,000,000)	20,000,000
Investment in unconsolidated subsidiaries	(1,421,000,000)	0
Prepaid long-term service agreement	(125,000,000)	(166,000,000)
Other investing activities	95,000,000	7,000,000
Net cash provided from (used for) investing activities	(16,640,000,000)	(4,880,000,000)
Financing Activities:
Increase (decrease) in notes payable, net	655,000,000	662,000,000
Proceeds —
Long-term debt issuances	14,091,000,000	3,992,000,000
Common stock issuances	3,265,000,000	136,000,000
Short-term borrowings	0	280,000,000
Redemptions and repurchases —
Long-term debt	(2,405,000,000)	(2,562,000,000)
Interest-bearing refundable deposits	0	(275,000,000)
Preferred and preference stock	0	(412,000,000)
Common stock	0	(115,000,000)
Short-term borrowings	(475,000,000)	(255,000,000)
Distributions to noncontrolling interests	(22,000,000)	(6,000,000)
Capital contributions from noncontrolling interests	367,000,000	274,000,000
Purchase of membership interests from noncontrolling interests	(129,000,000)	0
Payment of common stock dividends	(1,553,000,000)	(1,465,000,000)
Other financing activities	(151,000,000)	(63,000,000)
Net cash provided from (used for) financing activities	13,643,000,000	191,000,000
Net Change in Cash and Cash Equivalents	1,265,000,000	399,000,000
Cash and Cash Equivalents at Beginning of Period	1,404,000,000	710,000,000
Cash and Cash Equivalents at End of Period	2,669,000,000	1,109,000,000
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	766,000,000	590,000,000
Income taxes, net	(151,000,000)	(13,000,000)
Noncash Investing and Financing Items [Abstract]
Noncash transactions - Accrued property additions at end of period	578,000,000	483,000,000
Alabama Power [Member]
Operating Activities:
Net income (loss)	730,000,000	686,000,000
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	634,000,000	585,000,000
Deferred income taxes	267,000,000	85,000,000
Allowance for equity funds used during construction	(23,000,000)	(43,000,000)
Other, net	(23,000,000)	23,000,000
Changes in certain current assets and liabilities —
-Receivables	(4,000,000)	(160,000,000)
-Fossil fuel stock	18,000,000	69,000,000
-Other current assets	(46,000,000)	(10,000,000)
-Accounts payable	(113,000,000)	(106,000,000)
-Accrued taxes	203,000,000	371,000,000
-Retail fuel cost over recovery - short-term	(104,000,000)	81,000,000
-Other current liabilities	(4,000,000)	(2,000,000)
Net cash provided from (used for) operating activities	1,535,000,000	1,579,000,000
Investing Activities:
Property additions	(947,000,000)	(938,000,000)
Nuclear decommissioning trust fund purchases	(275,000,000)	(349,000,000)
Nuclear decommissioning trust fund sales	275,000,000	349,000,000
Cost of removal, net of salvage	(70,000,000)	(41,000,000)
Change in construction payables	(37,000,000)	(48,000,000)
Other investing activities	(28,000,000)	(22,000,000)
Net cash provided from (used for) investing activities	(1,082,000,000)	(1,049,000,000)
Proceeds —
Senior notes issuances	400,000,000	975,000,000
Capital contributions	253,000,000	13,000,000
Pollution control revenue bonds	0	80,000,000
Other long-term debt	45,000,000	0
Redemptions and repurchases —
Preferred and preference stock	0	(412,000,000)
Pollution control revenue bonds	0	(134,000,000)
Senior notes	(200,000,000)	(250,000,000)
Payment of common stock dividends	(574,000,000)	(428,000,000)
Other financing activities	(15,000,000)	(38,000,000)
Net cash provided from (used for) financing activities	(91,000,000)	(194,000,000)
Net Change in Cash and Cash Equivalents	362,000,000	336,000,000
Cash and Cash Equivalents at Beginning of Period	194,000,000	273,000,000
Cash and Cash Equivalents at End of Period	556,000,000	609,000,000
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	215,000,000	192,000,000
Income taxes, net	(70,000,000)	47,000,000
Noncash Investing and Financing Items [Abstract]
Noncash transactions - Accrued property additions at end of period	84,000,000	88,000,000
Georgia Power [Member]
Operating Activities:
Net income (loss)	1,227,000,000	1,077,000,000
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	794,000,000	766,000,000
Deferred income taxes	346,000,000	12,000,000
Allowance for equity funds used during construction	(36,000,000)	(24,000,000)
Deferred expenses	(40,000,000)	(45,000,000)
Pension, postretirement, and other employee benefits	(14,000,000)	40,000,000
Settlement of asset retirement obligations	(93,000,000)	(18,000,000)
Other, net	4,000,000	48,000,000
Changes in certain current assets and liabilities —
-Receivables	(162,000,000)	37,000,000
-Fossil fuel stock	128,000,000	141,000,000
-Prepaid income taxes	45,000,000	244,000,000
-Other current assets	17,000,000	(17,000,000)
-Accounts payable	39,000,000	(118,000,000)
-Accrued taxes	(22,000,000)	54,000,000
-Accrued compensation	(26,000,000)	(34,000,000)
-Other current liabilities	53,000,000	(3,000,000)
Net cash provided from (used for) operating activities	2,260,000,000	2,160,000,000
Investing Activities:
Property additions	(1,566,000,000)	(1,321,000,000)
Nuclear decommissioning trust fund purchases	(563,000,000)	(815,000,000)
Nuclear decommissioning trust fund sales	558,000,000	810,000,000
Cost of removal, net of salvage	(45,000,000)	(57,000,000)
Change in construction payables, net of joint owner portion	(139,000,000)	44,000,000
Prepaid long-term service agreement	(27,000,000)	(60,000,000)
Other investing activities	24,000,000	11,000,000
Net cash provided from (used for) investing activities	(1,758,000,000)	(1,388,000,000)
Financing Activities:
Increase (decrease) in notes payable, net	(63,000,000)	(26,000,000)
Proceeds —
Senior notes issuances	650,000,000	0
FFB loan	300,000,000	600,000,000
Capital contributions	294,000,000	41,000,000
Pollution control revenue bonds	0	274,000,000
Short-term borrowings	0	250,000,000
Redemptions and repurchases —
Pollution control revenue bonds	(4,000,000)	(268,000,000)
Senior notes	(700,000,000)	(525,000,000)
Short-term borrowings	0	(250,000,000)
Payment of common stock dividends	(979,000,000)	(776,000,000)
Other financing activities	(20,000,000)	(31,000,000)
Net cash provided from (used for) financing activities	(522,000,000)	(711,000,000)
Net Change in Cash and Cash Equivalents	(20,000,000)	61,000,000
Cash and Cash Equivalents at Beginning of Period	67,000,000	24,000,000
Cash and Cash Equivalents at End of Period	47,000,000	85,000,000
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	277,000,000	251,000,000
Income taxes, net	188,000,000	311,000,000
Noncash Investing and Financing Items [Abstract]
Noncash transactions - Accrued property additions at end of period	226,000,000	192,000,000
Gulf Power [Member]
Operating Activities:
Net income (loss)	115,000,000	127,000,000
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	134,000,000	105,000,000
Deferred income taxes	15,000,000	58,000,000
Other, net	(4,000,000)	5,000,000
Changes in certain current assets and liabilities —
-Receivables	(9,000,000)	18,000,000
-Fossil fuel stock	49,000,000	18,000,000
-Other current assets	3,000,000	32,000,000
-Accrued taxes	40,000,000	46,000,000
-Other current liabilities	30,000,000	2,000,000
Net cash provided from (used for) operating activities	373,000,000	411,000,000
Investing Activities:
Property additions	(106,000,000)	(189,000,000)
Cost of removal, net of salvage	(8,000,000)	(9,000,000)
Change in construction payables	(7,000,000)	(29,000,000)
Other investing activities	(6,000,000)	(6,000,000)
Net cash provided from (used for) investing activities	(127,000,000)	(233,000,000)
Financing Activities:
Increase (decrease) in notes payable, net	(42,000,000)	(34,000,000)
Proceeds —
Pollution control revenue bonds	0	13,000,000
Common stock issuances	0	20,000,000
Redemptions and repurchases —
Pollution control revenue bonds	0	(13,000,000)
Senior notes	(125,000,000)	(60,000,000)
Payment of common stock dividends	(90,000,000)	(98,000,000)
Other financing activities	6,000,000	(4,000,000)
Net cash provided from (used for) financing activities	(251,000,000)	(176,000,000)
Net Change in Cash and Cash Equivalents	(5,000,000)	2,000,000
Cash and Cash Equivalents at Beginning of Period	74,000,000	39,000,000
Cash and Cash Equivalents at End of Period	69,000,000	41,000,000
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	29,000,000	27,000,000
Income taxes, net	14,000,000	(37,000,000)
Noncash Investing and Financing Items [Abstract]
Noncash transactions - Accrued property additions at end of period	13,000,000	17,000,000
Mississippi Power [Member]
Operating Activities:
Net income (loss)	40,000,000	63,000,000
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	115,000,000	94,000,000
Deferred income taxes	34,000,000	518,000,000
Investment tax credits	0	25,000,000
Allowance for equity funds used during construction	(90,000,000)	(82,000,000)
Regulatory assets associated with Kemper IGCC	(13,000,000)	(56,000,000)
Estimated loss on Kemper IGCC	222,000,000	182,000,000
Income taxes receivable, non-current	0	(544,000,000)
Other, net	12,000,000	7,000,000
Changes in certain current assets and liabilities —
-Prepaid income taxes	38,000,000	(1,000,000)
-Other current assets	7,000,000	4,000,000
-Accounts payable	5,000,000	(32,000,000)
-Accrued taxes	95,000,000	24,000,000
-Over recovered regulatory clause revenues	(20,000,000)	59,000,000
-Mirror CWIP	0	99,000,000
-Customer liability associated with Kemper refunds	(73,000,000)	0
-Other current liabilities	0	(11,000,000)
Net cash provided from (used for) operating activities	372,000,000	349,000,000
Investing Activities:
Property additions	(592,000,000)	(626,000,000)
Change in construction payables	(25,000,000)	(31,000,000)
Capital grant proceeds	137,000,000	0
Other investing activities	(29,000,000)	(29,000,000)
Net cash provided from (used for) investing activities	(509,000,000)	(686,000,000)
Financing Activities:
Increase (decrease) in notes payable, net	0	475,000,000
Proceeds —
Capital contributions	227,000,000	153,000,000
Short-term borrowings	0	30,000,000
Long-term debt issuance to parent company	200,000,000	0
Other long-term debt	900,000,000	0
Redemptions and repurchases —
Short-term borrowings	(475,000,000)	(5,000,000)
Long-term debt to parent company	(225,000,000)	0
Other long-term debt	(425,000,000)	(350,000,000)
Other financing activities	(4,000,000)	(3,000,000)
Net cash provided from (used for) financing activities	198,000,000	300,000,000
Net Change in Cash and Cash Equivalents	61,000,000	(37,000,000)
Cash and Cash Equivalents at Beginning of Period	98,000,000	133,000,000
Cash and Cash Equivalents at End of Period	159,000,000	96,000,000
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	36,000,000	6,000,000
Income taxes, net	(231,000,000)	(55,000,000)
Noncash Investing and Financing Items [Abstract]
Noncash transactions - Accrued property additions at end of period	80,000,000	83,000,000
Issuance of promissory note to parent related to repayment of interest-bearing refundable deposits and accrued interest	0	301,000,000
Southern Power [Member]
Operating Activities:
Net income (loss)	354,000,000	196,000,000
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	262,000,000	187,000,000
Deferred income taxes	(668,000,000)	222,000,000
Investment tax credits	0	294,000,000
Amortization of investment tax credits	(25,000,000)	(14,000,000)
Deferred revenues	9,000,000	15,000,000
Collateral deposits	(80,000,000)	0
Accrued income taxes, non-current	0	100,000,000
Other, net	10,000,000	10,000,000
Changes in certain current assets and liabilities —
-Receivables	(82,000,000)	(28,000,000)
-Prepaid income taxes	(16,000,000)	(116,000,000)
-Other current assets	1,000,000	1,000,000
-Accounts payable	7,000,000	1,000,000
-Accrued taxes	483,000,000	(247,000,000)
-Other current liabilities	14,000,000	(12,000,000)
Net cash provided from (used for) operating activities	269,000,000	609,000,000
Investing Activities:
Business acquisitions, net of cash acquired	(1,134,000,000)	(1,128,000,000)
Property additions	(1,702,000,000)	(348,000,000)
Investment in restricted cash	(750,000,000)	0
Distributions of restricted cash	746,000,000	0
Change in construction payables	(69,000,000)	88,000,000
Payments pursuant to long-term service agreements	(58,000,000)	(65,000,000)
Other investing activities	(41,000,000)	(1,000,000)
Net cash provided from (used for) investing activities	(3,008,000,000)	(1,454,000,000)
Financing Activities:
Increase (decrease) in notes payable, net	692,000,000	18,000,000
Proceeds —
Senior notes issuances	1,531,000,000	650,000,000
Capital contributions	800,000,000	226,000,000
Other long-term debt	63,000,000	400,000,000
Redemptions and repurchases —
Senior notes	0	(525,000,000)
Other long-term debt	(84,000,000)	(3,000,000)
Distributions to noncontrolling interests	(22,000,000)	(6,000,000)
Capital contributions from noncontrolling interests	367,000,000	274,000,000
Purchase of membership interests from noncontrolling interests	(129,000,000)	0
Payment of common stock dividends	(204,000,000)	(98,000,000)
Other financing activities	(14,000,000)	(5,000,000)
Net cash provided from (used for) financing activities	3,000,000,000	931,000,000
Net Change in Cash and Cash Equivalents	261,000,000	86,000,000
Cash and Cash Equivalents at Beginning of Period	830,000,000	75,000,000
Cash and Cash Equivalents at End of Period	1,091,000,000	161,000,000
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	49,000,000	69,000,000
Income taxes, net	71,000,000	(215,000,000)
Noncash Investing and Financing Items [Abstract]
Noncash transactions - Accrued property additions at end of period	$ 210,000,000	$ 120,000,000

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Net cash paid for capitalized interest	$ 94	$ 88
Alabama Power [Member]
Net cash paid for capitalized interest	8	15
Georgia Power [Member]
Net cash paid for capitalized interest	15	10
Gulf Power [Member]
Net cash paid for capitalized interest	0	5
Mississippi Power [Member]
Interest paid	72	58
Net cash paid for capitalized interest	36	52
Southern Power [Member]
Net cash paid for capitalized interest	$ 32	$ 4

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 2,669	$ 1,404
Receivables —
Customer accounts receivable	1,718	1,058
Energy marketing receivable	526	0
Unbilled revenues	639	397
Under recovered regulatory clause revenues	54	63
Income taxes receivable, current	0	144
Other accounts and notes receivable	317	398
Accumulated provision for uncollectible accounts	(43)	(13)
Materials and supplies	1,268	1,061
Fossil fuel stock	664	868
Natural gas for sale	627	0
Vacation pay	178	178
Prepaid expenses	459	495
Other regulatory assets, current	414	402
Other current assets	168	71
Total current assets	9,658	6,526
Property, Plant, and Equipment:
In service	94,174	75,118
Less accumulated provision for depreciation	29,590	24,253
Plant in service, net of depreciation	64,584	50,865
Other utility plant, net	0	233
Nuclear fuel, at amortized cost	901	934
Construction work in progress	10,069	9,082
Total property, plant, and equipment	75,554	61,114
Other Property and Investments:
Goodwill	6,223	2
Equity investments in unconsolidated subsidiaries	1,541	6
Other intangible assets, net of amortization	942	317
Nuclear decommissioning trusts, at fair value	1,616	1,512
Leveraged leases	769	755
Miscellaneous property and investments	249	160
Total other property and investments	11,340	2,752
Deferred Charges and Other Assets:
Deferred charges related to income taxes	1,590	1,560
Unamortized loss on reacquired debt	228	227
Other regulatory assets, deferred	6,446	4,989
Income taxes receivable, non-current	413	413
Other deferred charges and assets -- non-affiliated	1,133	737
Total deferred charges and other assets	9,810	7,926
Total Assets	106,362	78,318
Current Liabilities:
Securities due within one year	2,254	2,674
Notes payable	1,670	1,376
Energy marketing trade payables	533	0
Accounts payable —
Accounts payable	1,732	1,905
Customer deposits	577	404
Accrued taxes —
Accrued income taxes	375	19
Other accrued taxes	641	484
Accrued interest	410	249
Accrued vacation pay	231	228
Accrued compensation	505	549
Asset retirement obligations, current	390	217
Liabilities from risk management activities	125	156
Other regulatory liabilities, current	99	278
Mandatorily redeemable noncontrolling interest	174	0
Other current liabilities	851	590
Total current liabilities	10,567	9,129
Long-term Debt:
Total Long-term Debt	41,550	24,688
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	14,218	12,322
Deferred credits related to income taxes	204	187
Accumulated deferred investment tax credits	1,721	1,219
Employee benefit obligations	3,022	2,582
Asset retirement obligations, deferred	4,124	3,542
Accrued Environmental Loss Contingencies, Noncurrent	415	42
Unrecognized tax benefits	381	370
Other cost of removal obligations	2,771	1,162
Other regulatory liabilities, deferred	401	254
Other deferred credits and liabilities	641	678
Total deferred credits and other liabilities	27,898	22,358
Total Liabilities	80,015	56,175
Redeemable Preferred Stock of Subsidiaries	118	118
Redeemable Noncontrolling Interest	49	43
Common Stockholders' Equity:
Common stock	4,900	4,572
Paid-in capital	9,217	6,282
Treasury, at cost	(30)	(142)
Retained earnings (accumulated deficit)	10,685	10,010
Accumulated other comprehensive income (loss)	(225)	(130)
Total common stockholders' equity	24,547	20,592
Preferred and Preference Stock of Subsidiaries	609	609
Noncontrolling Interests	1,024	781
Total Stockholders' Equity	26,180	21,982
Total Liabilities and Stockholders' Equity	106,362	78,318
Alabama Power [Member]
Current Assets:
Cash and cash equivalents	556	194
Receivables —
Customer accounts receivable	440	332
Unbilled revenues	155	119
Under recovered regulatory clause revenues	52	43
Income taxes receivable, current	0	142
Other accounts and notes receivable	43	20
Affiliated	30	50
Accumulated provision for uncollectible accounts	(9)	(10)
Materials and supplies	420	398
Fossil fuel stock	220	239
Vacation pay	66	66
Prepaid expenses	56	83
Other regulatory assets, current	73	115
Other current assets	9	10
Total current assets	2,111	1,801
Property, Plant, and Equipment:
In service	25,800	24,750
Less accumulated provision for depreciation	9,018	8,736
Plant in service, net of depreciation	16,782	16,014
Nuclear fuel, at amortized cost	345	363
Construction work in progress	473	801
Total property, plant, and equipment	17,600	17,178
Other Property and Investments:
Equity investments in unconsolidated subsidiaries	67	71
Nuclear decommissioning trusts, at fair value	781	737
Miscellaneous property and investments	105	96
Total other property and investments	953	904
Deferred Charges and Other Assets:
Deferred charges related to income taxes	518	522
Deferred under recovered regulatory clause revenues	87	99
Other regulatory assets, deferred	1,070	1,114
Other deferred charges and assets -- non-affiliated	118	103
Total deferred charges and other assets	1,793	1,838
Total Assets	22,457	21,721
Current Liabilities:
Securities due within one year	236	200
Accounts payable —
Affiliated	309	278
Other	233	410
Customer deposits	88	88
Accrued taxes —
Accrued income taxes	73	0
Other accrued taxes	125	38
Accrued interest	69	73
Accrued vacation pay	55	55
Accrued compensation	97	119
Liabilities from risk management activities	10	55
Other regulatory liabilities, current	1	240
Other current liabilities	65	39
Total current liabilities	1,361	1,595
Long-term Debt:
Total Long-term Debt	6,859	6,654
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	4,505	4,241
Deferred credits related to income taxes	67	70
Accumulated deferred investment tax credits	112	118
Employee benefit obligations	366	388
Asset retirement obligations, deferred	1,501	1,448
Other cost of removal obligations	695	722
Other regulatory liabilities, deferred	95	136
Deferred over recovered regulatory clause revenues	157	0
Other deferred credits and liabilities	56	76
Total deferred credits and other liabilities	7,554	7,199
Total Liabilities	15,774	15,448
Redeemable Preferred Stock	85	85
Preference Stock	196	196
Common Stockholders' Equity:
Common stock	1,222	1,222
Paid-in capital	2,607	2,341
Retained earnings (accumulated deficit)	2,604	2,461
Accumulated other comprehensive income (loss)	(31)	(32)
Total common stockholders' equity	6,402	5,992
Total Liabilities and Stockholders' Equity	22,457	21,721
Georgia Power [Member]
Current Assets:
Cash and cash equivalents	47	67
Receivables —
Customer accounts receivable	718	541
Unbilled revenues	298	188
Joint owner accounts receivable	46	227
Income taxes receivable, current	0	114
Other accounts and notes receivable	55	57
Affiliated	15	18
Accumulated provision for uncollectible accounts	(2)	(2)
Materials and supplies	470	449
Fossil fuel stock	274	402
Vacation pay	90	91
Prepaid income taxes	111	156
Other regulatory assets, current	115	123
Other current assets	89	92
Total current assets	2,326	2,523
Property, Plant, and Equipment:
In service	33,394	31,841
Less accumulated provision for depreciation	11,234	10,903
Plant in service, net of depreciation	22,160	20,938
Other utility plant, net	0	171
Nuclear fuel, at amortized cost	556	572
Construction work in progress	4,888	4,775
Total property, plant, and equipment	27,604	26,456
Other Property and Investments:
Equity investments in unconsolidated subsidiaries	61	64
Nuclear decommissioning trusts, at fair value	835	775
Miscellaneous property and investments	42	43
Total other property and investments	938	882
Deferred Charges and Other Assets:
Deferred charges related to income taxes	675	679
Other regulatory assets, deferred	2,530	2,152
Other deferred charges and assets -- non-affiliated	175	173
Total deferred charges and other assets	3,380	3,004
Total Assets	34,248	32,865
Current Liabilities:
Securities due within one year	458	712
Notes payable	95	158
Accounts payable —
Affiliated	451	411
Other	464	750
Customer deposits	265	264
Accrued taxes —
Accrued income taxes	14	12
Other accrued taxes	310	325
Accrued interest	110	99
Accrued vacation pay	62	62
Accrued compensation	118	142
Asset retirement obligations, current	313	179
Over recovered regulatory clause revenues, current	125	10
Other current liabilities	197	171
Total current liabilities	2,982	3,295
Long-term Debt:
Total Long-term Debt	10,114	9,616
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	5,969	5,627
Deferred credits related to income taxes	103	105
Accumulated deferred investment tax credits	199	204
Employee benefit obligations	906	949
Asset retirement obligations, deferred	2,241	1,737
Other deferred credits and liabilities	203	347
Total deferred credits and other liabilities	9,621	8,969
Total Liabilities	22,717	21,880
Redeemable Preferred Stock	45	45
Preference Stock	221	221
Common Stockholders' Equity:
Common stock	398	398
Paid-in capital	6,585	6,275
Retained earnings (accumulated deficit)	4,295	4,061
Accumulated other comprehensive income (loss)	(13)	(15)
Total common stockholders' equity	11,265	10,719
Total Liabilities and Stockholders' Equity	34,248	32,865
Gulf Power [Member]
Current Assets:
Cash and cash equivalents	69	74
Receivables —
Customer accounts receivable	94	76
Unbilled revenues	74	54
Under recovered regulatory clause revenues	2	20
Income taxes receivable, current	0	27
Other accounts and notes receivable	4	9
Affiliated	3	1
Accumulated provision for uncollectible accounts	(1)	(1)
Materials and supplies	56	56
Fossil fuel stock	59	108
Other regulatory assets, current	62	90
Other current assets	15	22
Total current assets	437	536
Property, Plant, and Equipment:
In service	5,073	5,045
Less accumulated provision for depreciation	1,387	1,296
Plant in service, net of depreciation	3,686	3,749
Other utility plant, net	0	62
Construction work in progress	64	48
Total property, plant, and equipment	3,750	3,859
Other Property and Investments:
Total other property and investments	4	4
Deferred Charges and Other Assets:
Deferred charges related to income taxes	59	61
Other regulatory assets, deferred	507	427
Other deferred charges and assets -- non-affiliated	45	33
Total deferred charges and other assets	611	521
Total Assets	4,802	4,920
Current Liabilities:
Securities due within one year	195	110
Notes payable	100	142
Accounts payable —
Affiliated	50	55
Other	41	44
Customer deposits	35	36
Accrued taxes —
Accrued income taxes	19	4
Other accrued taxes	34	9
Accrued interest	19	9
Accrued compensation	20	25
Deferred capacity expense, current	22	22
Liabilities from risk management activities	30	49
Other regulatory liabilities, current	28	22
Other current liabilities	41	40
Total current liabilities	634	567
Long-term Debt:
Total Long-term Debt	989	1,193
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	904	893
Employee benefit obligations	125	129
Deferred capacity expense	125	141
Asset retirement obligations, deferred	119	113
Accrued Environmental Loss Contingencies, Noncurrent	41	42
Other cost of removal obligations	248	233
Other regulatory liabilities, deferred	48	47
Other deferred credits and liabilities	41	60
Total deferred credits and other liabilities	1,651	1,658
Total Liabilities	3,274	3,418
Preference Stock	147	147
Common Stockholders' Equity:
Common stock	503	503
Paid-in capital	579	567
Retained earnings (accumulated deficit)	303	285
Accumulated other comprehensive income (loss)	(4)	0
Total common stockholders' equity	1,381	1,355
Total Liabilities and Stockholders' Equity	4,802	4,920
Mississippi Power [Member]
Current Assets:
Cash and cash equivalents	159	98
Receivables —
Customer accounts receivable	39	26
Unbilled revenues	47	36
Income taxes receivable, current	0	20
Other accounts and notes receivable	6	10
Affiliated	17	20
Materials and supplies	75	75
Fossil fuel stock	96	104
Prepaid income taxes	0	39
Other regulatory assets, current	118	95
Other current assets	10	8
Total current assets	567	531
Property, Plant, and Equipment:
In service	4,835	4,886
Less accumulated provision for depreciation	1,259	1,262
Plant in service, net of depreciation	3,576	3,624
Construction work in progress	2,525	2,254
Total property, plant, and equipment	6,101	5,878
Other Property and Investments:
Total other property and investments	12	11
Deferred Charges and Other Assets:
Deferred charges related to income taxes	330	290
Other regulatory assets, deferred	510	525
Income taxes receivable, non-current	544	544
Other deferred charges and assets -- non-affiliated	101	61
Total deferred charges and other assets	1,485	1,420
Total Assets	8,165	7,840
Current Liabilities:
Securities due within one year	343	728
Notes payable	25	500
Accounts payable —
Affiliated	92	85
Other	126	135
Customer deposits	16	16
Accrued taxes —
Accrued income taxes	110	0
Other accrued taxes	75	85
Accrued interest	20	18
Accrued compensation	21	26
Asset retirement obligations, current	36	22
Over recovered regulatory clause liabilities	76	96
Customer liability associated with Kemper refunds	1	73
Other current liabilities	37	52
Total current liabilities	978	1,836
Long-term Debt:
Long-term Debt, Affiliated	551	576
Long-term debt, non-affiliated	2,161	1,310
Total Long-term Debt	2,712	1,886
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	823	762
Deferred credits related to income taxes	7	8
Employee benefit obligations	146	153
Asset retirement obligations, deferred	154	154
Unrecognized tax benefits	382	368
Other cost of removal obligations	172	165
Other regulatory liabilities, deferred	76	71
Other deferred credits and liabilities	54	45
Total deferred credits and other liabilities	1,814	1,726
Total Liabilities	5,504	5,448
Redeemable Preferred Stock	33	33
Common Stockholders' Equity:
Common stock	38	38
Paid-in capital	3,124	2,893
Retained earnings (accumulated deficit)	(528)	(566)
Accumulated other comprehensive income (loss)	(6)	(6)
Total common stockholders' equity	2,628	2,359
Total Liabilities and Stockholders' Equity	8,165	7,840
Southern Power [Member]
Current Assets:
Cash and cash equivalents	1,091	830
Receivables —
Customer accounts receivable	121	75
Other accounts and notes receivable	25	19
Affiliated	67	30
Materials and supplies	163	63
Fossil fuel stock	14	16
Prepaid income taxes	61	45
Other current assets	32	30
Total current assets	1,574	1,108
Property, Plant, and Equipment:
In service	9,491	7,275
Less accumulated provision for depreciation	1,465	1,248
Plant in service, net of depreciation	8,026	6,027
Construction work in progress	1,652	1,137
Total property, plant, and equipment	9,678	7,164
Other Property and Investments:
Goodwill	2	2
Other intangible assets, net of amortization	389	317
Total other property and investments	391	319
Deferred Charges and Other Assets:
Prepaid long-term service agreements	151	166
Accumulated deferred income taxes	199	0
Other deferred charges and assets -- affiliated	3	9
Other deferred charges and assets -- non-affiliated	355	139
Total deferred charges and other assets	708	314
Total Assets	12,351	8,905
Current Liabilities:
Securities due within one year	60	403
Notes payable	828	137
Accounts payable —
Affiliated	91	66
Other	218	327
Accrued taxes —
Accrued income taxes	147	198
Other accrued taxes	16	5
Accrued interest	30	23
Business Combination, Contingent Consideration, Liability	30	36
Other current liabilities	97	44
Total current liabilities	1,517	1,239
Long-term Debt:
Total Long-term Debt	4,548	2,719
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	140	601
Accumulated deferred investment tax credits	1,385	889
Accrued income taxes, non-current	109	109
Asset retirement obligations, deferred	40	21
Deferred capacity revenues -- affiliated	19	17
Other deferred credits and liabilities	115	3
Total deferred credits and other liabilities	1,808	1,640
Total Liabilities	7,873	5,598
Redeemable Noncontrolling Interest	49	43
Common Stockholders' Equity:
Common stock	0	0
Paid-in capital	2,620	1,822
Retained earnings (accumulated deficit)	769	657
Accumulated other comprehensive income (loss)	16	4
Total common stockholders' equity	3,405	2,483
Noncontrolling Interests, Total	1,024	781
Total Stockholders' Equity	4,429	3,264
Total Liabilities and Stockholders' Equity	$ 12,351	$ 8,905

Condensed Consolidated Balance8

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Other intangible assets, accumulated amortization	$ 39	$ 12
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares authorized	1,500,000,000	1,500,000,000
Common stock, shares issued	981,000,000	915,000,000
Treasury shares at cost	800,000	3,400,000
Alabama Power [Member]
Common stock, par value (in dollars per share)	$ 40	$ 40
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares outstanding	30,537,500	30,537,500
Georgia Power [Member]
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares outstanding	9,261,500	9,261,500
Gulf Power [Member]
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares outstanding	5,642,717	5,642,717
Mississippi Power [Member]
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	1,130,000	1,130,000
Common stock, shares outstanding	1,121,000	1,121,000
Southern Power [Member]
Other intangible assets, accumulated amortization	$ 16	$ 12
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000	1,000,000
Common stock, shares outstanding	1,000	1,000

Introduction

Introduction	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
INTRODUCTION	INTRODUCTION The condensed quarterly financial statements of each registrant included herein have been prepared by such registrant, without audit, pursuant to the rules and regulations of the SEC. The Condensed Balance Sheets as of December 31, 2015 have been derived from the audited financial statements of each registrant. In the opinion of each registrant's management, the information regarding such registrant furnished herein reflects all adjustments, which, except as otherwise disclosed, are of a normal recurring nature, necessary to present fairly the results of operations for the periods ended September 30, 2016 and 2015 . Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, although each registrant believes that the disclosures regarding such registrant are adequate to make the information presented not misleading. Disclosures which would substantially duplicate the disclosures in the Form 10-K and details which have not changed significantly in amount or composition since the filing of the Form 10-K are generally omitted from this Quarterly Report on Form 10-Q unless specifically required by GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K. Due to the seasonal variations in the demand for energy, operating results for the periods presented are not necessarily indicative of the operating results to be expected for the full year. Southern Company's financial statements reflect its investments in its subsidiaries, including Southern Company Gas as a result of the Merger, on a consolidated basis. Southern Company Gas' results of operations and cash flows since July 1, 2016 and financial condition as of September 30, 2016 are reflected within Southern Company's consolidated amounts in these accompanying notes herein. Southern Company Gas continues to maintain reporting requirements as an SEC registrant and has filed its Quarterly Report on Form 10-Q with the SEC separately from this combined Form 10-Q. The equity method is used for entities in which Southern Company has significant influence but does not control, including Southern Company Gas' investment in Southern Natural Gas Company, L.L.C. (SNG), and for variable interest entities where Southern Company has an equity investment but is not the primary beneficiary. See Note (I) under " Southern Company – Merger with Southern Company Gas " and " – Investment in Southern Natural Gas " for additional information regarding the Merger and Southern Company Gas' investment in SNG, respectively. Certain prior year data presented in the financial statements have been reclassified to conform to the current year presentation. These reclassifications had no impact on the results of operations, financial position, or cash flows of any registrant. Recently Issued Accounting Standards On February 25, 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 requires lessees to recognize on the balance sheet a lease liability and a right-of-use asset for all leases. ASU 2016-02 also changes the recognition, measurement, and presentation of expense associated with leases and provides clarification regarding the identification of certain components of contracts that would represent a lease. The accounting required by lessors is relatively unchanged and there is no change to the accounting for existing leveraged leases. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The registrants are currently evaluating the new standard and have not yet determined its ultimate impact; however, adoption of ASU 2016-02 is expected to have a significant impact on the registrants' balance sheets. On March 30, 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). ASU 2016-09 changes the accounting for income taxes and the cash flow presentation for share-based payment award transactions. Most significantly, entities are required to recognize all excess tax benefits and deficiencies related to the exercise or vesting of stock compensation as income tax expense or benefit in the income statement. Southern Company and the traditional electric operating companies currently recognize any excess tax benefits and deficiencies related to the exercise and vesting of stock compensation as additional paid-in capital. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016. Early adoption is permitted and Southern Company and the traditional electric operating companies intend to adopt the ASU in the fourth quarter 2016. The adoption is not expected to have a material impact on the results of operations, financial position, or cash flows of Southern Company and the traditional electric operating companies. Affiliate Transactions In 2014, prior to Southern Company's acquisition of PowerSecure International, Inc. (PowerSecure) on May 9, 2016, Georgia Power entered into two agreements with PowerSecure to build solar power generation facilities at two U.S. Army bases, as approved by the Georgia PSC. Payments of approximately $108 million made by Georgia Power to PowerSecure under the two agreements since inception in 2014 are included in CWIP at September 30, 2016 . PowerSecure construction service costs of approximately $0.2 million are included in accounts payable, affiliated in Georgia Power's balance sheet at September 30, 2016 . On October 4, 2016, the two facilities began commercial operation. Prior to Southern Company Gas' completion of its acquisition of a 50% equity interest in SNG, Southern Company and Southern Company Gas had entered into long-term interstate natural gas transportation agreements with SNG. The interstate transportation service provided to the traditional electric operating companies, Southern Power, and Southern Company Gas by SNG pursuant to these agreements is governed by the terms and conditions of SNG's natural gas tariff and is subject to FERC regulation. For the period subsequent to Southern Company Gas' investment in SNG, transportation costs paid to SNG by Southern Company were approximately $16 million , including $8 million for Georgia Power, $2 million for Southern Power, and $1 million for Alabama Power. See Note (I) under " Southern Company – Acquisition of PowerSecure International, Inc. " and " – Investment in Southern Natural Gas " for additional information regarding Southern Company's acquisition of PowerSecure and Southern Company Gas' investment in SNG, respectively. Asset Retirement Obligations See Note 1 to the financial statements of Southern Company, Alabama Power, Georgia Power, Gulf Power, and Mississippi Power under "Asset Retirement Obligations and Other Costs of Removal" in Item 8 of the Form 10-K for additional information regarding Southern Company's and the traditional electric operating companies' asset retirement obligations (ARO) and the EPA's regulation of CCR. See Note 1 to the financial statements of Southern Power under "Asset Retirement Obligations" in Item 8 of the Form 10-K for additional information regarding Southern Power's AROs. The cost estimates below are based on information as of September 30, 2016 . The cost estimates for AROs related to the disposal of CCR are based on various assumptions related to closure and post-closure costs, timing of future cash outlays, inflation and discount rates, and the potential methods for complying with the Disposal of Coal Combustion Residuals from Electric Utilities final rule requirements for closure in place or by other methods. As further analysis is performed, including evaluation of the expected method of compliance, refinement of assumptions underlying the cost estimates, such as the quantities of CCR at each site, and the determination of timing, including the potential for closing ash ponds prior to the end of their currently anticipated useful life, the traditional electric operating companies expect to continue to periodically update these estimates. As of September 30, 2016 , details of the AROs included in the registrants' Condensed Balance Sheets were as follows: Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Balance at beginning of year $ 3,759 $ 1,448 $ 1,916 $ 130 $ 177 $ 21 Liabilities incurred 41 5 — — 15 18 Liabilities settled (117 ) (12 ) (93 ) — (12 ) — Accretion 119 55 56 2 3 1 Cash flow revisions 712 31 675 2 7 — Balance at end of period $ 4,514 $ 1,527 $ 2,554 $ 134 $ 190 $ 40 The traditional electric operating companies' increases in cash flow revisions for the nine months ended September 30, 2016 primarily relate to changes in ash pond closure strategy. The increase for Georgia Power reflects its decision in June 2016 to cease operating and stop receiving coal ash at all of its ash ponds within the next three years and to eventually close all of its ash ponds either by removal, consolidation, and/or recycling for the beneficial use of coal ash or through closure in place using advanced engineering methods. Goodwill and Other Intangible Assets As of September 30, 2016, goodwill was as follows: As of September 30, 2016 (in millions) Southern Company $ 6,223 Southern Power $ 2 As of September 30, 2016, other intangible assets were as follows: As of September 30, 2016 Estimated Useful Life Gross Carrying Amount Accumulated Amortization Other Intangible Assets, Net (in millions) Southern Company Other intangible assets subject to amortization: Customer relationships 11-26 years $ 268 $ (16 ) $ 252 Trade names 5-28 years 158 (3 ) 155 Patents 3-10 years 4 — 4 Backlog 5 years 5 — 5 Storage and transportation contracts 1-5 years 64 (4 ) 60 Software and other 1-12 years 2 — 2 PPA fair value adjustments 19-20 years 405 (16 ) 389 Total other intangible assets subject to amortization $ 906 $ (39 ) $ 867 Other intangible assets not subject to amortization: Federal Communications Commission licenses $ 75 $ — $ 75 Total other intangible assets $ 981 $ (39 ) $ 942 Southern Power Other intangible assets subject to amortization: PPA fair value adjustments 19-20 years $ 405 $ (16 ) $ 389 Amortization associated with other intangible assets was as follows: Three Months Ended Nine Months Ended September 30, 2016 (in millions) Southern Company $ 25 $ 27 Southern Power $ 2 $ 4 At December 31, 2015, other intangible assets consisted primarily of Southern Power's PPA fair value adjustments with a net carrying amount of $317 million . The increases in goodwill and other intangible assets primarily relate to Southern Company's acquisitions of PowerSecure on May 9, 2016 and Southern Company Gas on July 1, 2016. See Note 12 to the financial statements of Southern Company under "Southern Power" and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information regarding Southern Power's PPA fair value adjustments. Also see Note (I) under " Southern Company – Acquisition of PowerSecure International, Inc. " and " – Merger with Southern Company Gas " for additional information. Natural Gas for Sale Southern Company Gas' natural gas distribution utilities, with the exception of Nicor Gas, carry natural gas inventory on a weighted average cost of gas (WACOG) basis. Nicor Gas' natural gas inventory is carried at cost on a last-in, first-out (LIFO) basis. Inventory decrements occurring during the year that are restored prior to year-end are charged to cost of natural gas at the estimated annual replacement cost. Inventory decrements that are not restored prior to year-end are charged to cost of natural gas at the actual LIFO cost of the layers liquidated. The cost of natural gas, including inventory costs, is recovered from customers under a purchased gas recovery mechanism adjusted for differences between actual costs and amounts billed; therefore, LIFO liquidations have no impact on Southern Company's net income . Southern Company Gas' other natural gas inventories are carried at the lower of weighted average cost or current market price, with cost determined on a WACOG basis. For any declines in market prices below the WACOG considered to be other than temporary, an adjustment is recorded to reduce the value of natural gas inventories to market value .

Contingencies and Regulatory Ma

Contingencies and Regulatory Matters	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
CONTINGENCIES AND REGULATORY MATTERS	CONTINGENCIES AND REGULATORY MATTERS See Note 3 to the financial statements of the registrants in Item 8 of the Form 10-K for information relating to various lawsuits, other contingencies, and regulatory matters. General Litigation Matters Nicor Gas and Nicor Energy Services Company, wholly-owned subsidiaries of Southern Company Gas, and Nicor Inc. are defendants in a putative class action initially filed in September 2011 in state court in Cook County, Illinois. The plaintiffs purport to represent a class of the customers who purchased the Gas Line Comfort Guard product from Nicor Energy Services Company and variously allege that the marketing, sale, and billing of the Gas Line Comfort Guard product violated the Illinois Consumer Fraud and Deceptive Business Practices Act, constituting common law fraud and resulting in unjust enrichment of these entities. The plaintiffs seek, on behalf of the classes they purport to represent, actual and punitive damages, interest, costs, attorney fees, and injunctive relief. On October 26, 2016, the court held a hearing on the plaintiffs' motion for class certification and the defendants' motion for summary judgment on all of the plaintiffs' claims. The ultimate outcome of this matter cannot be determined at this time. Each registrant is subject to certain claims and legal actions arising in the ordinary course of business. In addition, business activities of Southern Company's subsidiaries are subject to extensive governmental regulation related to public health and the environment, such as regulation of air emissions and water discharges. Litigation over environmental issues and claims of various types, including property damage, personal injury, common law nuisance, and citizen enforcement of environmental requirements such as air quality and water standards, has occurred throughout the U.S. This litigation has included claims for damages alleged to have been caused by CO 2 and other emissions, CCR, and alleged exposure to hazardous materials, and/or requests for injunctive relief in connection with such matters. The ultimate outcome of such pending or potential litigation against each registrant and any subsidiaries cannot be predicted at this time; however, for current proceedings not specifically reported herein or in Note 3 to the financial statements of each registrant in Item 8 of the Form 10-K, management does not anticipate that the ultimate liabilities, if any, arising from such current proceedings would have a material effect on such registrant's financial statements. Environmental Remediation The Southern Company system must comply with environmental laws and regulations that cover the handling and disposal of waste and releases of hazardous substances. Under these various laws and regulations, the Southern Company system could incur substantial costs to clean up affected sites. The traditional electric operating companies, and Southern Company Gas' natural gas distribution utilities in Illinois, New Jersey, Georgia, and Florida, have each received authority from their respective state PSCs or other applicable state regulatory agencies to recover approved environmental compliance costs through regulatory mechanisms. These regulatory mechanisms are adjusted annually or as necessary within limits approved by the state PSCs or other applicable state regulatory agencies. Georgia Power's environmental remediation liability as of September 30, 2016 was $23 million . Georgia Power has been designated or identified as a potentially responsible party (PRP) at sites governed by the Georgia Hazardous Site Response Act and/or by the federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), including a site in Brunswick, Georgia on the CERCLA National Priorities List. The PRPs at the Brunswick site have completed a removal action as ordered by the EPA. On July 29, 2016, Honeywell International, Inc. and Georgia Power entered into a consent decree with the EPA to perform additional remediation at the site. Additional response actions at the site are anticipated. In September 2015, Georgia Power entered into an allocation agreement with another PRP, under which that PRP will be responsible (as between Georgia Power and that PRP) for paying and performing certain investigation, assessment, remediation, and other incidental activities at the Brunswick site, including costs associated with implementation of the consent decree. Assessment and potential cleanup of other sites are anticipated. The ultimate outcome of these matters will depend upon the success of defenses asserted, the ultimate number of PRPs participating in the cleanup, and numerous other factors and cannot be determined at this time; however, as a result of Georgia Power's regulatory treatment for environmental remediation expenses, these matters are not expected to have a material impact on Southern Company's or Georgia Power's financial statements. Gulf Power's environmental remediation liability includes estimated costs of environmental remediation projects of approximately $46 million as of September 30, 2016 . These estimated costs primarily relate to site closure criteria by the Florida Department of Environmental Protection (FDEP) for potential impacts to soil and groundwater from herbicide applications at Gulf Power substations. The schedule for completion of the remediation projects is subject to FDEP approval. The projects have been approved by the Florida PSC for recovery through Gulf Power's environmental cost recovery clause; therefore, these liabilities have no impact on net income. The final outcome of these matters cannot be determined at this time. However, based on the currently known conditions at these sites and the nature and extent of activities relating to these sites, management of Southern Company and Gulf Power does not believe that additional liabilities, if any, at these sites would be material to their respective financial statements . Southern Company Gas' environmental remediation liability as of September 30, 2016 was $433 million based on the estimated cost of environmental investigation and remediation associated with known current and former operating sites. These environmental remediation expenditures are recoverable from customers through rate mechanisms approved by the applicable state regulatory agencies of Southern Company Gas' natural gas distribution utilities, with the exception of one site representing $5 million of the total accrued remediation costs. The ultimate outcome of these matters cannot be determined at this time; however, these matters are not expected to have a material impact on Southern Company's financial statements. I n September 2015, the EPA filed an administrative complaint and notice of opportunity for hearing against Nicor Gas. The complaint alleges violation of the regulatory requirements applicable to polychlorinated biphenyls in the Nicor Gas natural gas distribution system and the EPA seeks a total civil penalty of approximately $0.3 million . The ultimate resolution of this matter cannot be determined at this time; however, the final disposition of this matter is not expected to have a material impact on Southern Company's financial statements. FERC Matters Municipal and Rural Associations Tariff See Note 3 to the financial statements of Mississippi Power under "FERC Matters" in Item 8 of the Form 10-K for additional information regarding a settlement agreement entered into by Mississippi Power regarding the establishment of a regulatory asset for Kemper IGCC-related costs. See " Integrated Coal Gasification Combined Cycle " herein for information regarding Mississippi Power's construction of the Kemper IGCC. On March 31, 2016, Mississippi Power reached a settlement agreement with its wholesale customers and filed a request with the FERC for an increase in wholesale base revenues under the Municipal and Rural Associations (MRA) cost-based electric tariff, primarily as a result of placing scrubbers for Plant Daniel Units 1 and 2 in service in November 2015. The settlement agreement, accepted by the FERC, effective for services rendered beginning May 1, 2016, provides that base rates under the MRA cost-based electric tariff will produce additional annual base revenues of $7 million . Additionally, under the settlement agreement, the tariff customers agreed to similar regulatory treatment for MRA tariff ratemaking as the treatment approved for retail ratemaking under the December 2015 Mississippi PSC order authorizing rates providing recovery of assets previously placed in service (In-Service Asset Rate Order). This regulatory treatment primarily includes (i) recovery of the Kemper IGCC assets currently operational and providing service to customers and other related costs, (ii) amortization of the Kemper IGCC-related regulatory assets included in rates under the settlement agreement over 36 months, (iii) Kemper IGCC-related expenses included in rates under the settlement agreement no longer being deferred and charged to expense, and (iv) removing all of the Kemper IGCC CWIP from rate base with a corresponding increase in accrual of AFUDC. The additional resulting AFUDC is estimated to be approximately $11 million through the Kemper IGCC's projected in-service date of December 31, 2016. Fuel Cost Recovery Mississippi Power has a wholesale MRA and a Market Based (MB) fuel cost recovery factor. At September 30, 2016 , the amount of over-recovered wholesale MRA fuel costs included in the balance sheets was $17 million compared to $24 million at December 31, 2015 . At September 30, 2016 and December 31, 2015 , the amount of over-recovered wholesale MB fuel costs included in the balance sheets was $1 million . Effective with the first billing cycle for September 2016, fuel rates decreased $11 million annually for wholesale MRA customers and $1 million annually for wholesale MB customers. See Note 3 to the financial statements of Mississippi Power under "FERC Matters – Fuel Cost Recovery" in Item 8 of the Form 10-K for additional information. Market-Based Rate Authority The traditional electric operating companies and Southern Power have authority from the FERC to sell electricity at market-based rates. Since 2008, that authority, for certain balancing authority areas, has been conditioned on compliance with the requirements of an energy auction, which the FERC found to be tailored mitigation that addresses potential market power concerns. In accordance with FERC regulations governing such authority, the traditional electric operating companies and Southern Power filed a triennial market power analysis in 2014, which included continued reliance on the energy auction as tailored mitigation. In April 2015, the FERC issued an order finding that the traditional electric operating companies' and Southern Power's existing tailored mitigation may not effectively mitigate the potential to exert market power in certain areas served by the traditional electric operating companies and in some adjacent areas. The FERC directed the traditional electric operating companies and Southern Power to show why market-based rate authority should not be revoked in these areas or to provide a mitigation plan to further address market power concerns. The traditional electric operating companies and Southern Power filed a request for rehearing in May 2015 and in June 2015 filed their response with the FERC. The ultimate outcome of this matter cannot be determined at this time. Retail Regulatory Matters Alabama Power See Note 3 to the financial statements of Southern Company and Alabama Power under "Retail Regulatory Matters – Alabama Power" and "Retail Regulatory Matters," respectively, in Item 8 of the Form 10-K for additional information regarding Alabama Power's recovery of retail costs through various regulatory clauses and accounting orders. The balance of each regulatory clause recovery on the balance sheet follows: Regulatory Clause Balance Sheet Line Item September 30, December 31, 2015 (in millions) Rate CNP Compliance Under recovered regulatory clause revenues $ — $ 43 Deferred over recovered regulatory clause revenues 23 — Rate CNP PPA Under recovered regulatory clause revenues 52 99 Deferred under recovered regulatory clause revenues 87 — Retail Energy Cost Recovery Other regulatory liabilities, current — 238 Deferred over recovered regulatory clause revenues 134 — Natural Disaster Reserve Other regulatory liabilities, deferred 71 75 Environmental Accounting Order In April 2016, as part of its environmental compliance strategy, Alabama Power ceased using coal at Plant Greene County Units 1 and 2 ( 300 MWs representing Alabama Power's ownership interest) and began operating Units 1 and 2 solely on natural gas in June 2016 and July 2016, respectively. Georgia Power Rate Plans See Note 3 to the financial statements of Southern Company and Georgia Power under "Retail Regulatory Matters – Georgia Power – Rate Plans" and "Retail Regulatory Matters – Rate Plans," respectively, in Item 8 of the Form 10-K for additional information. Georgia Power's revenues from regulated retail operations are collected through various rate mechanisms subject to the oversight of the Georgia PSC. Georgia Power currently recovers its costs from the regulated retail business through the 2013 ARP, which includes traditional base tariff rates, Demand-Side Management tariffs, Environmental Compliance Cost Recovery tariffs, and Municipal Franchise Fee tariffs. In addition, financing costs related to the construction of Plant Vogtle Units 3 and 4 are being collected through the NCCR tariff and fuel costs are collected through separate fuel cost recovery tariffs. See " Nuclear Construction " herein and Note 3 to the financial statements of Georgia Power under "Retail Regulatory Matters – Nuclear Construction" and Southern Company under "Retail Regulatory Matters – Georgia Power – Nuclear Construction" in Item 8 of the Form 10-K for additional information regarding the NCCR tariff. Also see " Fuel Cost Recovery " herein and Note 3 to the financial statements of Georgia Power under "Retail Regulatory Matters – Fuel Cost Recovery" and Southern Company under "Retail Regulatory Matters – Georgia Power – Fuel Cost Recovery" in Item 8 of the Form 10-K for additional information regarding fuel cost recovery. Pursuant to the terms and conditions of a settlement agreement related to Southern Company's acquisition of Southern Company Gas approved by the Georgia PSC on April 14, 2016, Georgia Power's 2013 ARP will continue in effect until December 31, 2019, and Georgia Power will be required to file its next base rate case by July 1, 2019. Furthermore, through December 31, 2019, Georgia Power and Atlanta Gas Light Company (collectively, Utilities) each will retain their respective merger savings, net of transition costs, as defined in the settlement agreement; through December 31, 2022, such net merger savings applicable to each utility will be shared on a 60 / 40 basis between their respective customers and the Utilities; thereafter, all merger savings will be retained by customers. See Note (I) under " Southern Company – Merger with Southern Company Gas " for additional information regarding the Merger. Integrated Resource Plan See Note 3 to the financial statements of Southern Company and Georgia Power under "Retail Regulatory Matters – Georgia Power – Integrated Resource Plan" and "Retail Regulatory Matters – Integrated Resource Plan," respectively, in Item 8 of the Form 10-K for additional information regarding Georgia Power's triennial Integrated Resource Plan (2016 IRP). On July 28, 2016, the Georgia PSC voted to approve the 2016 IRP including the decertification and retirement of Plant Mitchell Units 3, 4A, and 4B ( 217 MWs) and Plant Kraft Unit 1 combustion turbine ( 17 MWs), as well as the decertification of the Intercession City unit ( 143 MWs total capacity). On August 2, 2016, the Plant Mitchell and Plant Kraft units were retired. On August 31, 2016, Georgia Power sold its 33% ownership interest in the Intercession City unit to Duke Energy Florida, Inc. Additionally, the Georgia PSC approved Georgia Power's environmental compliance strategy and related expenditures proposed in the 2016 IRP, including measures taken to comply with existing government-imposed environmental mandates, subject to limits on expenditures for Plant McIntosh Unit 1 and Plant Hammond Units 1 through 4. The Georgia PSC approved the reclassification of the remaining net book value of Plant Mitchell Unit 3 and costs associated with materials and supplies remaining at the unit retirement date to a regulatory asset. Recovery of the unit's net book value will continue through December 31, 2019, as provided in the 2013 ARP. The timing of the recovery of the remaining balance of the unit's net book value as of December 31, 2019 and costs associated with materials and supplies remaining at the unit retirement date will be deferred for consideration in Georgia Power's base rate case required to be filed by July 1, 2019. The Georgia PSC also approved the Renewable Energy Development Initiative to procure an additional 1,200 MWs of renewable resources primarily utilizing market-based prices established through a competitive bidding process with expected in-service dates between 2018 and 2021. Additionally, 200 MWs of self-build capacity for use by Georgia Power was approved, as well as consideration for no more than 200 MWs of capacity as part of a renewable commercial and industrial program. The Georgia PSC also approved recovery of costs up to $99 million through June 30, 2019 to preserve the nuclear option at a future generation site in Stewart County, Georgia. The timing of cost recovery will be determined by the Georgia PSC in a future base rate case. The ultimate outcome of this matter cannot be determined at this time. Fuel Cost Recovery See Note 3 to the financial statements of Southern Company and Georgia Power under "Retail Regulatory Matters – Georgia Power – Fuel Cost Recovery" and "Retail Regulatory Matters – Fuel Cost Recovery," respectively, in Item 8 of the Form 10-K for additional information. As of September 30, 2016 and December 31, 2015 , Georgia Power's over recovered fuel balance totaled $125 million and $116 million , respectively. For September 30, 2016 , the balance is included in over recovered regulatory clause revenues, current on Georgia Power's Condensed Balance Sheets and in other current liabilities on Southern Company's Condensed Balance Sheets. For December 31, 2015 , the balance is included in over recovered regulatory clause revenues, current and other deferred credits and liabilities on Georgia Power's Condensed Balance Sheets and in other current liabilities and other deferred credits and liabilities on Southern Company's Condensed Balance Sheets. On May 17, 2016, the Georgia PSC approved Georgia Power's request to decrease fuel rates by 15% effective June 1, 2016, which will reduce annual billings by approximately $313 million . Georgia Power is currently scheduled to file its next fuel case by February 28, 2017. Fuel cost recovery revenues are adjusted for differences in actual recoverable fuel costs and amounts billed in current regulated rates. Accordingly, changes in the billing factor will not have a significant effect on Southern Company's or Georgia Power's revenues or net income, but will affect cash flow. Storm Damage Recovery As of September 30, 2016 , the balance in Georgia Power's regulatory asset related to storm damage was $94 million . During October 2016, Hurricane Matthew caused significant damage to Georgia Power's transmission and distribution facilities. The total amount of restoration costs related to this hurricane is estimated to be between $130 million and $155 million , which will be charged to capital accounts or to the storm damage reserve. Georgia Power is accruing $30 million annually through December 31, 2019, as provided in the 2013 ARP, to the storm damage reserve to cover the operating and maintenance costs of damages from major storms to its transmission and distribution facilities, which is recoverable through base rates. The rate of recovery of storm damage costs after December 31, 2019 is expected to be adjusted in Georgia Power's base rate case required to be filed by July 1, 2019. As a result of this regulatory treatment, costs related to storms are not expected to have a material impact on Southern Company's or Georgia Power's financial statements. See Note 3 to the financial statements of Southern Company under "Retail Regulatory Matters – Georgia Power – Storm Damage Recovery" and Note 1 to the financial statements of Georgia Power under "Storm Damage Recovery" in Item 8 of the Form 10-K for additional information regarding Georgia Power's storm damage reserve. Nuclear Construction See Note 3 to the financial statements of Southern Company and Georgia Power under "Retail Regulatory Matters – Georgia Power – Nuclear Construction" and "Retail Regulatory Matters – Nuclear Construction," respectively, in Item 8 of the Form 10-K for additional information regarding Georgia Power's construction of Plant Vogtle Units 3 and 4, Vogtle Construction Monitoring (VCM) reports, the NCCR tariff, the Vogtle Construction Litigation (as defined below), and the Contractor Settlement Agreement (as defined below). In 2008, Georgia Power, acting for itself and as agent for the Vogtle Owners, entered into an agreement with the Contractor, pursuant to which the Contractor agreed to design, engineer, procure, construct, and test Plant Vogtle Units 3 and 4 (Vogtle 3 and 4 Agreement). Under the terms of the Vogtle 3 and 4 Agreement, the Vogtle Owners agreed to pay a purchase price subject to certain price escalations and adjustments, including fixed escalation amounts and index-based adjustments, as well as adjustments for change orders, and performance bonuses for early completion and unit performance. The Vogtle 3 and 4 Agreement also provides for liquidated damages upon the Contractor's failure to fulfill the schedule and performance guarantees, subject to a cap. In addition, the Vogtle 3 and 4 Agreement provides for limited cost sharing by the Vogtle Owners for Contractor costs under certain conditions (which have not occurred), with maximum additional capital costs under this provision attributable to Georgia Power (based on Georgia Power's ownership interest) of approximately $114 million . Each Vogtle Owner is severally (and not jointly) liable for its proportionate share, based on its ownership interest, of all amounts owed to the Contractor under the Vogtle 3 and 4 Agreement. Georgia Power's proportionate share is 45.7% . On December 31, 2015, Westinghouse acquired Stone & Webster, Inc. from Chicago Bridge & Iron Company, N.V. (CB&I) and changed the name of Stone & Webster, Inc. to WECTEC Global Project Services Inc. (WECTEC). Certain obligations of Westinghouse and WECTEC under the Vogtle 3 and 4 Agreement were originally guaranteed by Toshiba Corporation (Westinghouse's parent company) and The Shaw Group Inc. (which is now a subsidiary of CB&I), respectively. On March 9, 2016, in connection with Westinghouse's acquisition of WECTEC and pursuant to the settlement agreement described below, the guarantee of The Shaw Group Inc. was terminated. The guarantee of Toshiba Corporation remains in place. In the event of certain credit rating downgrades of any Vogtle Owner, such Vogtle Owner will be required to provide a letter of credit or other credit enhancement. Additionally, as a result of credit rating downgrades of Toshiba Corporation, Westinghouse provided the Vogtle Owners with letters of credit in an aggregate amount of $920 million in accordance with, and subject to adjustment under, the terms of the Vogtle 3 and 4 Agreement. The Vogtle Owners may terminate the Vogtle 3 and 4 Agreement at any time for their convenience, provided that the Vogtle Owners will be required to pay certain termination costs. The Contractor may terminate the Vogtle 3 and 4 Agreement under certain circumstances, including certain Vogtle Owner suspension or delays of work, action by a governmental authority to permanently stop work, certain breaches of the Vogtle 3 and 4 Agreement by the Vogtle Owners, Vogtle Owner insolvency, and certain other events. In 2009, the Georgia PSC voted to certify construction of Plant Vogtle Units 3 and 4. Georgia Power is required to file semi-annual VCM reports with the Georgia PSC by February 28 and August 31 each year. If the projected construction capital costs to be borne by Georgia Power increase by 5% above the certified cost or the projected in-service dates are significantly extended, Georgia Power is required to seek an amendment to the Plant Vogtle Units 3 and 4 certificate from the Georgia PSC. In February 2013, Georgia Power requested an amendment to the certificate to increase the estimated in-service capital cost of Plant Vogtle Units 3 and 4 from $4.4 billion to $4.8 billion and to extend the estimated in-service dates to the fourth quarter 2017 (from April 2016) and the fourth quarter 2018 (from April 2017) for Plant Vogtle Units 3 and 4, respectively. In October 2013, the Georgia PSC approved a stipulation (2013 Stipulation) between Georgia Power and the Georgia PSC Staff to waive the requirement to amend the Plant Vogtle Units 3 and 4 certificate until the completion of Plant Vogtle Unit 3 or earlier if deemed appropriate by the Georgia PSC and Georgia Power. On April 15, 2015, the Georgia PSC issued a procedural order in connection with the twelfth VCM report, which included a requested amendment (Requested Amendment) to the Plant Vogtle Units 3 and 4 certificate to reflect the Contractor's revised forecast for completion of Plant Vogtle Units 3 and 4 (second quarter of 2019 and second quarter of 2020, respectively) and to increase the estimated total in-service capital cost of Plant Vogtle Units 3 and 4 to $5.0 billion . Pursuant to the Georgia PSC's procedural order, the Georgia PSC deemed the Requested Amendment unnecessary and withdrawn until the completion of construction of Plant Vogtle Unit 3 consistent with the 2013 Stipulation. The Georgia PSC recognized that the certified cost and the 2013 Stipulation do not constitute a cost recovery cap. In accordance with the Georgia Integrated Resource Planning Act, any costs incurred by Georgia Power in excess of the certified amount will be included in rate base, provided Georgia Power shows the costs to be reasonable and prudent. On December 31, 2015, Westinghouse and the Vogtle Owners entered into a definitive settlement agreement (Contractor Settlement Agreement) to resolve disputes between the Vogtle Owners and the Contractor under the Vogtle 3 and 4 Agreement, including litigation that was pending in the U.S. District Court for the Southern District of Georgia (Vogtle Construction Litigation). Effective December 31, 2015, Georgia Power, acting for itself and as agent for the other Vogtle Owners, and the Contractor entered into an amendment to the Vogtle 3 and 4 Agreement to implement the Contractor Settlement Agreement. The Contractor Settlement Agreement and the related amendment to the Vogtle 3 and 4 Agreement (i) restrict the Contractor's ability to seek further increases in the contract price by clarifying and limiting the circumstances that constitute nuclear regulatory changes in law; (ii) provide for enhanced dispute resolution procedures; (iii) revise the guaranteed substantial completion dates to match the current estimated in-service dates of June 30, 2019 for Unit 3 and June 30, 2020 for Unit 4; (iv) provide that delay liquidated damages will commence from the current estimated nuclear fuel loading date for each unit, which is December 31, 2018 for Unit 3 and December 31, 2019 for Unit 4; and (v) provide that Georgia Power, based on its ownership interest, will pay to the Contractor and capitalize to the project cost approximately $350 million , of which approximately $256 million had been paid as of September 30, 2016 . In addition, the Contractor Settlement Agreement provides for the resolution of other open existing items relating to the scope of the project under the Vogtle 3 and 4 Agreement, including cyber security, for which costs were reflected in Georgia Power's previously disclosed in-service cost estimate. Further, as part of the settlement and Westinghouse's acquisition of WECTEC: (i) Westinghouse engaged Fluor Enterprises, Inc., a subsidiary of Fluor Corporation, as a new construction subcontractor; and (ii) the Vogtle Owners, CB&I, and The Shaw Group Inc. entered into mutual releases of any and all claims arising out of events or circumstances in connection with the construction of Plant Vogtle Units 3 and 4 that occurred on or before the date of the Contractor Settlement Agreement. On January 5, 2016, the Vogtle Construction Litigation was dismissed with prejudice. The Georgia PSC has approved fourteen VCM reports covering the periods through December 31, 2015, including construction capital costs incurred, which through that date totaled $3.3 billion . On January 21, 2016, Georgia Power submitted the Contractor Settlement Agreement and the related amendment to the Vogtle 3 and 4 Agreement to the Georgia PSC for its review. In accordance with the Georgia PSC's subsequent order, on April 5, 2016, Georgia Power filed supplemental information in support of the Contractor Settlement Agreement and Georgia Power's position that all construction costs to date have been prudently incurred and that the current estimated in-service capital cost and schedule are reasonable. On October 20, 2016, Georgia Power and the Georgia PSC Staff entered into a settlement agreement (Vogtle Cost Settlement Agreement) resolving the following prudence matters: (i) none of the $3.3 billion of costs incurred through December 31, 2015 and reflected in the fourteenth VCM report will be disallowed from rate base on the basis of imprudence; (ii) the Contractor Settlement Agreement is reasonable and prudent and none of the amounts paid or to be paid pursuant to the Contractor Settlement Agreement should be disallowed from rate base on the basis of imprudence; (iii) financing costs on verified and approved capital costs will be deemed prudent provided they are incurred prior to December 31, 2019 and December 31, 2020 for Plant Vogtle Units 3 and 4, respectively; and (iv) (a) the in-service capital cost forecast will be adjusted to $5.680 billion (Revised Forecast), which includes a contingency of $240 million above Georgia Power's current forecast of $5.440 billion , (b) capital costs incurred up to the Revised Forecast will be presumed to be reasonable and prudent with the burden of proof on any party challenging such costs, and (c) Georgia Power would have the burden to show that any capital costs above the Revised Forecast are reasonable and prudent. Under the terms of the Vogtle Cost Settlement Agreement, the certified in-service capital cost for purposes of calculating the NCCR tariff will remain at $4.418 billion . Construction capital costs above $4.418 billion will accrue AFUDC through commercial operation. The ROE used to calculate the NCCR tariff will be reduced from 10.95% (the ROE rate setting point authorized by the Georgia PSC in the 2013 ARP) to 10.00% effective January 1, 2016. For purposes of the AFUDC calculation, the ROE on costs between $4.418 billion and $5.440 billion will also be 10.00% and the ROE on any amounts above $5.440 billion would be Georgia Power's average cost of long-term debt. If the Georgia PSC adjusts Georgia Power's ROE rate setting point in a rate case prior to Plant Vogtle Units 3 and 4 being placed into retail rate base, then the ROE for purposes of calculating both the NCCR tariff and AFUDC will likewise be 95 basis points lower than the revised ROE rate setting point. If Plant Vogtle Units 3 and 4 are not commercially operational by December 31, 2020, then (i) the ROE for purposes of calculating the NCCR tariff will be reduced an additional 300 basis points, and may, at the Georgia PSC's discretion, be accrued to be used for the benefit of customers, until such time as the units reach commercial operation and (ii) the ROE used to calculate AFUDC will be Georgia Power's average cost of long-term debt. Under the terms of the Vogtle Cost Settlement Agreement, Plant Vogtle Units 3 and 4 will be placed into retail rate base on December 31, 2020 or upon reaching commercial operation, whichever is later. The Georgia PSC will determine for retail ratemaking pu

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS As of September 30, 2016 , assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows: Fair Value Measurements Using As of September 30, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Southern Company Assets: Energy-related derivatives (a) $ 203 $ 190 $ — $ — $ 393 Interest rate derivatives — 19 — — 19 Foreign currency derivatives — 23 — — 23 Nuclear decommissioning trusts (b) 660 938 — 18 1,616 Cash equivalents 1,680 — — — 1,680 Other investments 9 — 1 — 10 Total $ 2,552 $ 1,170 $ 1 $ 18 $ 3,741 Liabilities: Energy-related derivatives $ 267 $ 274 $ — $ — $ 541 Interest rate derivatives — 7 — — 7 Foreign currency derivatives — 24 — — 24 Contingent consideration — — 18 — 18 Total $ 267 $ 305 $ 18 $ — $ 590 Alabama Power Assets: Energy-related derivatives $ — $ 8 $ — $ — $ 8 Nuclear decommissioning trusts (c) Domestic equity 373 72 — — 445 Foreign equity 49 49 — — 98 U.S. Treasury and government agency securities — 22 — — 22 Corporate bonds 22 148 — — 170 Mortgage and asset backed securities — 21 — — 21 Private Equity — — — 18 18 Other — 7 — — 7 Cash equivalents 410 — — — 410 Total $ 854 $ 327 $ — $ 18 $ 1,199 Liabilities: Energy-related derivatives $ — $ 21 $ — $ — $ 21 Fair Value Measurements Using As of September 30, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Georgia Power Assets: Energy-related derivatives $ — $ 15 $ — $ — $ 15 Interest rate derivatives — 10 — — 10 Nuclear decommissioning trusts (c) (d) Domestic equity 197 1 — — 198 Foreign equity — 125 — 125 U.S. Treasury and government agency securities — 59 — — 59 Municipal bonds — 70 — — 70 Corporate bonds — 172 — — 172 Mortgage and asset backed securities — 149 — — 149 Other 19 43 — — 62 Cash equivalents 32 — — — 32 Total $ 248 $ 644 $ — $ — $ 892 Liabilities: Energy-related derivatives $ — $ 16 $ — $ — $ 16 Gulf Power Assets: Energy-related derivatives $ — $ 1 $ — $ — $ 1 Cash equivalents 20 — — — 20 Total $ 20 $ 1 $ — $ — $ 21 Liabilities: Energy-related derivatives $ — $ 51 $ — $ — $ 51 Interest rate derivatives — 6 — — 6 Total $ — $ 57 $ — $ — $ 57 Mississippi Power Assets: Energy-related derivatives $ — $ 1 $ — $ — $ 1 Cash equivalents 137 — — — 137 Total $ 137 $ 1 $ — $ — $ 138 Liabilities: Energy-related derivatives $ — $ 21 $ — $ — $ 21 Interest rate derivatives — 1 — — 1 Total $ — $ 22 $ — $ — $ 22 Fair Value Measurements Using As of September 30, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Southern Power Assets: Energy-related derivatives $ — $ 3 $ — $ — $ 3 Foreign currency derivatives — 23 — — 23 Cash equivalents 647 — — — 647 Total $ 647 $ 26 $ — $ — $ 673 Liabilities: Energy-related derivatives $ — $ 3 $ — $ — $ 3 Foreign currency derivatives — 24 — — 24 Contingent consideration — — 18 — 18 Total $ — $ 27 $ 18 $ — $ 45 (a) Excludes $7 million associated with certain weather derivatives accounted for based on intrinsic value rather than fair value. (b) For additional detail, see the nuclear decommissioning trusts sections for Alabama Power and Georgia Power in this table. (c) Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. (d) Includes the investment securities pledged to creditors and collateral received and excludes payables related to the securities lending program. As of September 30, 2016 , approximately $42 million of the fair market value of Georgia Power's nuclear decommissioning trust funds' securities were on loan to creditors under the funds' managers' securities lending program. Southern Company, Alabama Power, and Georgia Power continue to elect the option to fair value investment securities held in the nuclear decommissioning trust funds. The fair value of the funds at Southern Company, including reinvested interest and dividends and excluding the funds' expenses, increased by $49 million and $116 million , respectively, for the three and nine months ended September 30, 2016 , and decreased by $65 million and $33 million , respectively, for the three and nine months ended September 30, 2015 . Alabama Power recorded an increase in fair value of $26 million and $66 million , respectively, for the three and nine months ended September 30, 2016 and a decrease in fair value of $39 million and $19 million , respectively, for the three and nine months ended September 30, 2015 as a change in regulatory liabilities related to its AROs. Georgia Power recorded an increase in fair value of $23 million and $50 million , respectively, for the three and nine months ended September 30, 2016 and a decrease in fair value of $26 million and $14 million , respectively, for the three and nine months ended September 30, 2015 as a change in its regulatory asset related to its AROs. Valuation Methodologies The energy-related derivatives primarily consist of exchange-traded and over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and occasionally, implied volatility of interest rate options. The fair value of cross-currency swaps reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future foreign currency exchange rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and discount rates. The interest rate derivatives and cross-currency swaps are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note (H) for additional information on how these derivatives are used. The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. For fair value measurements of the investments within the nuclear decommissioning trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available. See Note 1 to the financial statements of Southern Company, Alabama Power, and Georgia Power under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information. Southern Power has contingent payment obligations related to certain acquisitions whereby Southern Power is obligated to pay generation-based payments to the seller over a 10 -year period beginning at the commercial operation date. The obligation is measured at fair value using significant inputs such as forecasted facility generation in MW-hours, a fixed dollar amount per MW-hour, and a discount rate, and is evaluated periodically. The fair value of contingent consideration reflects the net present value of expected payments and any change arising from forecasted generation is expected to be immaterial. "Other investments" include investments that are not traded in the open market. The fair value of these investments have been determined based on market factors including comparable multiples and the expectations regarding cash flows and business plan executions. As of September 30, 2016 , the fair value measurements of private equity investments held in the nuclear decommissioning trust that are calculated at net asset value per share (or its equivalent) as a practical expedient, as well as the nature and risks of those investments, were as follows: As of September 30, 2016: Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period (in millions) Southern Company $ 18 $ 27 Not Applicable Not Applicable Alabama Power $ 18 $ 27 Not Applicable Not Applicable Private equity funds include a fund-of-funds that invests in high-quality private equity funds across several market sectors, a fund that invests in real estate assets, and a fund that acquires companies to create resale value. Private equity funds do not have redemption rights. Distributions from these funds will be received as the underlying investments in the funds are liquidated. Liquidations are expected to occur at various times over the next ten years . As of September 30, 2016 , other financial instruments for which the carrying amount did not equal fair value were as follows: Carrying Amount Fair Value (in millions) Long-term debt, including securities due within one year: Southern Company $ 43,668 $ 47,227 Alabama Power $ 7,091 $ 7,961 Georgia Power $ 10,398 $ 11,582 Gulf Power $ 1,184 $ 1,267 Mississippi Power $ 2,981 $ 2,967 Southern Power $ 4,608 $ 4,821 The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on the current rates available to the registrants.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY Earnings per Share For Southern Company, the only difference in computing basic and diluted earnings per share is attributable to awards outstanding under the stock option and performance share plans. See Note 8 to the financial statements of Southern Company in Item 8 of the Form 10-K for information on the stock option and performance share plans. The effect of both stock options and performance share award units was determined using the treasury stock method. Shares used to compute diluted earnings per share were as follows: Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 (in millions) As reported shares 968 910 940 910 Effect of options and performance share award units 7 2 5 3 Diluted shares 975 912 945 913 Stock options and performance share award units that were not included in the diluted earnings per share calculation because they were anti-dilutive were immaterial for the three and nine months ended September 30, 2016 and were 15 million and 1 million for the three and nine months ended September 30, 2015 , respectively. Changes in Stockholders' Equity The following table presents year-to-date changes in stockholders' equity of Southern Company: Number of Common Shares Common Preferred and Preference Stock of Subsidiaries Total Issued Treasury Noncontrolling Interests (*) (in thousands) (in millions) Balance at December 31, 2015 915,073 (3,352 ) $ 20,592 $ 609 $ 781 $ 21,982 Consolidated net income attributable to Southern Company — — 2,226 — — 2,226 Other comprehensive income (loss) — — (95 ) — — (95 ) Stock issued 65,725 2,599 3,265 — — 3,265 Stock-based compensation — — 119 — — 119 Cash dividends on common stock — — (1,553 ) — — (1,553 ) Contributions from noncontrolling interests — — — — 357 357 Distributions to noncontrolling interests — — — — (21 ) (21 ) Purchase of membership interests from noncontrolling interests — — — — (129 ) (129 ) Net income attributable to noncontrolling interests — — — — 36 36 Other — (46 ) (7 ) — — (7 ) Balance at September 30, 2016 980,798 (799 ) $ 24,547 $ 609 $ 1,024 $ 26,180 Balance at December 31, 2014 908,502 (725 ) $ 19,949 $ 756 $ 221 $ 20,926 Consolidated net income attributable to Southern Company — — 2,096 — — 2,096 Other comprehensive income (loss) — — (7 ) — — (7 ) Stock issued 3,769 — 136 — — 136 Stock-based compensation — — 78 — — 78 Stock repurchased, at cost — (2,599 ) (115 ) — — (115 ) Cash dividends on common stock — — (1,465 ) — — (1,465 ) Preference stock redemption — — — (150 ) — (150 ) Contributions from noncontrolling interests — — — — 429 429 Distributions to noncontrolling interests — — — — (13 ) (13 ) Net income attributable to noncontrolling interests — — — — 13 13 Other — (8 ) (8 ) 3 — (5 ) Balance at September 30, 2015 912,271 (3,332 ) $ 20,664 $ 609 $ 650 $ 21,923 (*) Primarily related to Southern Power Company and excludes redeemable noncontrolling interests. See Note 10 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information.

Financing

Financing	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
FINANCING	FINANCING Bank Credit Arrangements Bank credit arrangements provide liquidity support to the registrants' commercial paper borrowings and the traditional electric operating companies' pollution control revenue bonds. The amount of variable rate pollution control revenue bonds outstanding requiring liquidity support as of September 30, 2016 was approximately $1.9 billion (comprised of approximately $890 million at Alabama Power, $868 million at Georgia Power, $82 million at Gulf Power, and $40 million at Mississippi Power). In addition, at September 30, 2016 , the traditional electric operating companies had approximately $358 million (comprised of approximately $87 million at Alabama Power, $250 million at Georgia Power, and $21 million at Gulf Power) of fixed rate pollution control revenue bonds outstanding that were required to be reoffered within the next 12 months. See Note 6 to the financial statements of each registrant under "Bank Credit Arrangements" in Item 8 of the Form 10-K and " Financing Activities " herein for additional information. The following table outlines the committed credit arrangements by company as of September 30, 2016 : Expires Executable Term Loans Due Within One Year Company 2016 2017 2018 2020 Total Unused One Year Two Years Term Out No Term Out (in millions) (in millions) (in millions) (in millions) Southern Company (a) $ — $ — $ 1,000 $ 1,250 $ 2,250 $ 2,250 $ — $ — $ — $ — Alabama Power — 35 500 800 1,335 1,335 — — — 35 Georgia Power — — — 1,750 1,750 1,732 — — — — Gulf Power 50 65 165 — 280 280 45 — 45 70 Mississippi Power 100 75 — — 175 150 — 15 15 160 Southern Power Company (b) — — — 600 600 532 — — — — Southern Company Gas (c) — 75 1,925 — 2,000 1,947 — — — — Other — 55 — — 55 55 20 — 20 35 Southern Company Consolidated $ 150 $ 305 $ 3,590 $ 4,400 $ 8,445 $ 8,281 $ 65 $ 15 $ 80 $ 300 (a) Represents the Southern Company parent entity. (b) Excluding its subsidiaries. See " Southern Power Project Credit Facilities " below and Note (I) under " Southern Power " for additional information. (c) Southern Company Gas guarantees the obligations of Southern Company Gas Capital, which is the borrower of $1.3 billion of these arrangements. Southern Company Gas' committed credit arrangements also include $700 million restricted for working capital needs of Nicor Gas. On May 24, 2016, Southern Company's $8.1 billion Bridge Agreement to provide Merger financing, to the extent necessary, was terminated. Subject to applicable market conditions, Southern Company and its subsidiaries expect to renew or replace their bank credit arrangements as needed, prior to expiration. In connection therewith, Southern Company and its subsidiaries may extend the maturity dates and/or increase or decrease the lending commitments thereunder. Southern Power Project Credit Facilities In connection with the construction of solar facilities by RE Garland Holdings LLC, RE Roserock LLC, and RE Tranquillity LLC, indirect subsidiaries of Southern Power, each subsidiary entered into separate credit agreements (Project Credit Facilities), which are non-recourse to Southern Power (other than the subsidiary party to the agreement). Each Project Credit Facility provides (a) a senior secured construction loan credit facility, (b) a senior secured bridge loan facility, and (c) a senior secured letter of credit facility that is secured by the membership interests of the respective project company, with proceeds directed to finance project costs related to the respective solar facilities. Each Project Credit Facility is secured by the assets of the applicable project subsidiary and membership interests of the applicable project subsidiary. The table below summarizes each Project Credit Facility as of September 30, 2016 . Project Maturity Date Construction Loan Facility Bridge Loan Facility Total Loan Facility Loan Facility Undrawn Letter of Credit Facility Letter of Credit Facility Undrawn (in millions) Garland Earlier of PPA COD or November 30, 2016 $ 86 $ 308 $ 394 $ 21 $ 49 $ 23 Roserock Earlier of PPA COD or November 30, 2016 (*) 63 180 243 34 23 16 Tranquillity October 14, 2016 86 172 258 12 77 26 Total $ 235 $ 660 $ 895 $ 67 $ 149 $ 65 (*) Subsequent to September 30, 2016, Roserock extended the maturity date of its Project Credit Facility to December 31, 2016. The Project Credit Facilities above had total amounts outstanding as of September 30, 2016 of $828 million at a weighted average interest rate of 2.05% . For the three-month period ended September 30, 2016 , these credit agreements had a maximum amount outstanding of $828 million and an average amount outstanding of $805 million at a weighted average interest rate of 2.02% . Furthermore, in connection with the acquisition of the Henrietta solar facility on July 1, 2016, a subsidiary of Southern Power assumed a $217 million construction loan, which was fully repaid prior to September 30, 2016 . For the three -month period ended September 30, 2016 , this credit agreement had a maximum amount outstanding of $217 million and an average amount outstanding of $137 million at a weighted average interest rate of 2.21% . Financing Activities The following table outlines the long-term debt financing activities for Southern Company and its subsidiaries for the first nine months of 2016 : Company Senior Note Issuances Senior Note Maturities and Redemptions Revenue Other Long-Term Debt Issuances Other Long-Term Debt Redemptions and Maturities (a) (in millions) Southern Company (b) $ 8,500 $ 500 $ — $ 800 $ — Alabama Power 400 200 — 45 — Georgia Power 650 700 4 300 5 Gulf Power — 125 — 2 — Mississippi Power — — — 1,100 652 Southern Power 1,531 — — 63 84 Southern Company Gas (c) 900 300 — — — Other — — — — 60 Elimination (d) — — — (200 ) (225 ) Southern Company Consolidated $ 11,981 $ 1,825 $ 4 $ 2,110 $ 576 (a) Includes reductions in capital lease obligations resulting from cash payments under capital leases. (b) Represents the Southern Company parent entity. (c) Reflects only long-term debt financing activities occurring subsequent to completion of the Merger. The senior notes were issued by Southern Company Gas Capital and guaranteed by Southern Company Gas. (d) Intercompany loans from Southern Company to Mississippi Power eliminated in Southern Company's Consolidated Financial Statements. Southern Company In May 2016, Southern Company issued the following series of senior notes for an aggregate principal amount of $8.5 billion : • $0.5 billion of 1.55% Senior Notes due July 1, 2018; • $1.0 billion of 1.85% Senior Notes due July 1, 2019; • $1.5 billion of 2.35% Senior Notes due July 1, 2021; • $1.25 billion of 2.95% Senior Notes due July 1, 2023; • $1.75 billion of 3.25% Senior Notes due July 1, 2026; • $0.5 billion of 4.25% Senior Notes due July 1, 2036; and • $2.0 billion of 4.40% Senior Notes due July 1, 2046. The net proceeds were used to fund a portion of the consideration for the Merger and related transaction costs and for other general corporate purposes. In September 2016, Southern Company issued $800 million aggregate principal amount of Series 2016A 5.25% Junior Subordinated Notes due October 1, 2076. The proceeds were used to repay short-term indebtedness that was incurred to repay at maturity $500 million aggregate principal amount of Southern Company's Series 2011A 1.95% Senior Notes due September 1, 2016 and for other general corporate purposes. Alabama Power In January 2016, Alabama Power issued $400 million aggregate principal amount of Series 2016A 4.30% Senior Notes due January 2, 2046. The proceeds were used to repay at maturity $200 million aggregate principal amount of Alabama Power's Series FF 5.20% Senior Notes due January 15, 2016 and for general corporate purposes, including Alabama Power's continuous construction program. In March 2016, Alabama Power entered into three bank term loan agreements with maturity dates of March 2021, in an aggregate principal amount of $45 million , one of which bears interest at 2.38% per annum and two of which bear interest based on three-month LIBOR. Georgia Power In March 2016, Georgia Power issued $325 million aggregate principal amount of Series 2016A 3.25% Senior Notes due April 1, 2026 and $325 million aggregate principal amount of Series 2016B 2.40% Senior Notes due April 1, 2021. An amount equal to the proceeds from the Series 2016A 3.25% Senior Notes due April 1, 2026 will be allocated to eligible green expenditures, including financing of or investments in solar generating facilities or electric vehicle charging infrastructure, or payments under PPAs served by solar or wind generating facilities. The proceeds from the Series 2016B 2.40% Senior Notes due April 1, 2021 were used to repay at maturity $250 million aggregate principal amount of Georgia Power's Series 2013B Floating Rate Senior Notes due March 15, 2016, to repay a portion of Georgia Power's short-term indebtedness, and for general corporate purposes, including Georgia Power's continuous construction program. In June 2016, Georgia Power made additional borrowings under the FFB Credit Facility in an aggregate principal amount of $300 million at a 2.571% interest rate through the final maturity date of February 20, 2044. The proceeds were used to reimburse Georgia Power for Eligible Project Costs relating to the construction of Plant Vogtle Units 3 and 4. Gulf Power In May 2016, Gulf Power redeemed $125 million aggregate principal amount of its Series 2011A 5.75% Senior Notes due June 1, 2051. Also in May 2016, Gulf Power entered into an 11 -month floating rate bank loan bearing interest based on one-month LIBOR. This short-term loan was for $100 million aggregate principal amount and the proceeds were used to repay existing indebtedness and for working capital and other general corporate purposes. Mississippi Power On January 28, 2016, Mississippi Power issued a promissory note for up to $275 million to Southern Company, which matures in December 2017, bearing interest based on one-month LIBOR. During the first nine months of 2016, Mississippi Power borrowed $100 million under this promissory note and an additional $100 million under a separate promissory note issued to Southern Company in November 2015. On March 8, 2016, Mississippi Power entered into an unsecured term loan agreement with a syndicate of financial institutions for an aggregate amount of $1.2 billion . Mississippi Power borrowed $900 million on March 8, 2016 under the term loan agreement and the remaining $300 million on October 7, 2016. Mississippi Power used the initial proceeds to repay $900 million in maturing bank loans on March 8, 2016 and the remaining $300 million to repay at maturity Mississippi Power's Series 2011A 2.35% Senior Notes due October 15, 2016. The term loan pursuant to this agreement matures on April 1, 2018 and bears interest based on one-month LIBOR. On June 27, 2016, Mississippi Power received a capital contribution from Southern Company of $225 million , the proceeds of which were used to repay to Southern Company a portion of the promissory note issued in November 2015. As of September 30, 2016 , the amount of outstanding promissory notes to Southern Company totaled $551 million . In June 2016, Mississippi Power renewed a $10 million short-term note, which matures on June 30, 2017, bearing interest based on three-month LIBOR. Southern Power In June 2016, Southern Power issued €600 million aggregate principal amount of Series 2016A 1.00% Senior Notes due June 20, 2022 and €500 million aggregate principal amount of Series 2016B 1.85% Senior Notes due June 20, 2026. The proceeds are being allocated to renewable energy generation projects. Southern Power's obligations under its euro-denominated fixed-rate notes were effectively converted to fixed-rate U.S. dollars at issuance through cross-currency swaps, removing foreign currency exchange risk associated with the interest and principal payments. See Note (H) under " Foreign Currency Derivatives " for additional information. In September 2016, Southern Power issued $290 million aggregate principal amount of Series 2016C 2.75% Senior Notes due September 20, 2023. The proceeds were used for general corporate purposes, including Southern Power's growth strategy and continuous construction program, as well as repayment of amounts outstanding under the Project Credit Facilities. Also in September 2016, Southern Power repaid $80 million of an outstanding $400 million floating rate bank loan and extended the maturity date of the remaining $320 million from September 2016 to September 2018. In addition, Southern Power entered into a $60 million aggregate principal amount floating rate bank loan bearing interest based on one-month LIBOR due September 2017. The proceeds were used to repay existing indebtedness and for other general corporate purposes. In addition, Southern Power issued $34 million in letters of credit during the nine months ended September 30, 2016 . During the nine months ended September 30, 2016 , Southern Power's subsidiaries incurred an additional $691 million of short-term borrowings pursuant to the Project Credit Facilities at a weighted average interest rate of 2.05% . Furthermore, in connection with the acquisition of the Henrietta solar facility, a subsidiary of Southern Power assumed a $217 million construction loan, which was fully repaid prior to September 30, 2016 . In addition, Southern Power's subsidiaries issued $16 million in letters of credit. Southern Company Gas In September 2016, Southern Company Gas Capital issued $350 million aggregate principal amount of 2.45% Senior Notes due October 1, 2023 and $550 million aggregate principal amount of 3.95% Senior Notes due October 1, 2046, both of which are guaranteed by Southern Company Gas. The proceeds were used to repay a $360 million promissory note issued to Southern Company for the purpose of funding a portion of the purchase price for Southern Company Gas' 50% equity interest in SNG, to fund Southern Company Gas' purchase of Piedmont Natural Gas Company, Inc.'s (Piedmont) interest in SouthStar Energy Services, LLC (SouthStar), to make a voluntary pension contribution, to repay at maturity $120 million aggregate principal amount of Series A Floating Rate Senior Notes due October 27, 2016, and for general corporate purposes. See Note (I) under " Southern Company – Investment in Southern Natural Gas " and " – Acquisition of Remaining Interest in SouthStar " for additional information regarding Southern Company Gas' investment in SNG and purchase of Piedmont's interest in SouthStar, respectively.

Retirement Benefits

Retirement Benefits	9 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]
RETIREMENT BENEFITS	RETIREMENT BENEFITS Southern Company has a defined benefit, trusteed, pension plan covering substantially all employees. The qualified pension plan is funded in accordance with requirements of the Employee Retirement Income Security Act of 1974, as amended. No mandatory contributions to the qualified pension plan are anticipated for the year ending December 31, 2016 . Southern Company also provides certain defined benefit pension plans for a selected group of management and highly compensated employees. Benefits under these non-qualified pension plans are funded on a cash basis. In addition, Southern Company provides certain medical care and life insurance benefits for retired employees through other postretirement benefit plans. The traditional electric operating companies fund related other postretirement trusts to the extent required by their respective regulatory commissions. See Note 2 to the financial statements of Southern Company, Alabama Power, Georgia Power, Gulf Power, and Mississippi Power in Item 8 of the Form 10-K for additional information. Southern Company Gas has a defined benefit, trusteed, pension plan covering eligible employees. The qualified pension plan is funded in accordance with requirements of the Employee Retirement Income Security Act of 1974, as amended. Southern Company Gas made a $125 million voluntary contribution to the qualified pension plan in September 2016. Southern Company Gas also provides certain defined benefit and defined contribution plans for a selected group of management and highly compensated employees. Benefits under these non-qualified plans are largely unfunded and benefits are primarily paid using corporate assets. In addition, Southern Company Gas provides certain medical care and life insurance benefits for eligible retired employees through a postretirement benefit plan. Southern Company Gas also has a separate unfunded supplemental retirement health care plan that provides medical care and life insurance benefits to employees of discontinued businesses. Components of the net periodic benefit costs for the three and nine months ended September 30, 2016 and 2015 were as follows: Pension Plans Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Three Months Ended September 30, 2016 Service cost $ 68 $ 14 $ 17 $ 3 $ 3 Interest cost 110 23 34 5 4 Expected return on plan assets (203 ) (46 ) (64 ) (9 ) (9 ) Amortization: Prior service costs 3 1 1 — 1 Net (gain)/loss 45 10 14 2 2 Net periodic pension cost $ 23 $ 2 $ 2 $ 1 $ 1 Nine Months Ended September 30, 2016 Service cost $ 192 $ 43 $ 52 $ 9 $ 9 Interest cost 311 71 102 14 14 Expected return on plan assets (577 ) (138 ) (193 ) (26 ) (26 ) Amortization: Prior service costs 10 2 4 1 1 Net (gain)/loss 120 30 41 5 5 Net periodic pension cost $ 56 $ 8 $ 6 $ 3 $ 3 Three Months Ended September 30, 2015 Service cost $ 65 $ 14 $ 18 $ 3 $ 3 Interest cost 111 26 38 5 5 Expected return on plan assets (181 ) (44 ) (62 ) (8 ) (8 ) Amortization: Prior service costs 6 2 2 1 — Net (gain)/loss 53 14 19 2 3 Net periodic pension cost $ 54 $ 12 $ 15 $ 3 $ 3 Nine Months Ended September 30, 2015 Service cost $ 193 $ 44 $ 54 $ 9 $ 9 Interest cost 333 79 115 15 16 Expected return on plan assets (543 ) (133 ) (188 ) (24 ) (25 ) Amortization: Prior service costs 19 5 7 1 1 Net (gain)/loss 161 41 57 7 8 Net periodic pension cost $ 163 $ 36 $ 45 $ 8 $ 9 Postretirement Benefits Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Three Months Ended September 30, 2016 Service cost $ 6 $ 1 $ 2 $ — $ — Interest cost 20 5 7 1 — Expected return on plan assets (16 ) (6 ) (6 ) — — Amortization: Prior service costs 1 1 — — — Net (gain)/loss 5 — 3 — 1 Net periodic postretirement benefit cost $ 16 $ 1 $ 6 $ 1 $ 1 Nine Months Ended September 30, 2016 Service cost $ 17 $ 4 $ 5 $ 1 $ 1 Interest cost 55 14 22 2 2 Expected return on plan assets (44 ) (19 ) (17 ) (1 ) (1 ) Amortization: Prior service costs 4 3 1 — — Net (gain)/loss 12 1 7 — 1 Net periodic postretirement benefit cost $ 44 $ 3 $ 18 $ 2 $ 3 Three Months Ended September 30, 2015 Service cost $ 6 $ 1 $ 2 $ 1 $ — Interest cost 20 5 9 — 1 Expected return on plan assets (15 ) (6 ) (6 ) — — Amortization: Prior service costs 1 2 — — — Net (gain)/loss 4 — 2 — — Net periodic postretirement benefit cost $ 16 $ 2 $ 7 $ 1 $ 1 Nine Months Ended September 30, 2015 Service cost $ 17 $ 4 $ 5 $ 1 $ 1 Interest cost 59 15 26 2 3 Expected return on plan assets (44 ) (19 ) (18 ) (1 ) (1 ) Amortization: Prior service costs 3 3 — — — Net (gain)/loss 13 1 8 — — Net periodic postretirement benefit cost $ 48 $ 4 $ 21 $ 2 $ 3

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES See Note 5 to the financial statements of each registrant in Item 8 of the Form 10-K for additional tax information. Current and Deferred Income Taxes Net Operating Loss Southern Company expects to be in a consolidated net operating loss (NOL) position for income tax purposes for the 2016 tax year. The NOL will limit the amount of positive cash flows resulting from bonus depreciation, ITCs, and PTCs for the tax year and will significantly increase deferred tax assets for the NOL and tax credit carryforwards. Portions of the NOL are expected to be carried back to prior tax years and forward to the 2017 tax year, which could further increase existing tax credit carryforwards . The ultimate outcome of this matter cannot be determined at this time. Tax Credit Carryforwards Southern Company had federal ITC and PTC carryforwards (primarily related to Southern Power) totaling $1.2 billion and $26 million , respectively, as of September 30, 2016 and $554 million and $1 million , respectively, as of December 31, 2015. Additionally, Southern Company had $165 million of state ITC carryforwards for the state of Georgia as of September 30, 2016 compared to $188 million as of December 31, 2015. See " Unrecognized Tax Benefits " herein for further information. The federal ITC carryforwards as of September 30, 2016 begin expiring in 2034 but are expected to be utilized by the end of 2021. The PTC carryforwards as of September 30, 2016 begin expiring in 2035 but are expected to be utilized by the end of 2021. The state ITC carryforwards for the state of Georgia as of September 30, 2016 expire between 2020 and 2026 but are expected to be fully utilized by the end of 2022. Effective Tax Rate Southern Company Southern Company's effective tax rate is typically lower than the statutory rate due to employee stock plans' dividend deduction, non-taxable AFUDC equity, and federal income tax benefits from ITCs and PTCs. Southern Company's effective tax rate was 29.1% for the nine months ended September 30, 2016 compared to 33.5% for the corresponding period in 2015 . The effective tax rate decrease was primarily due to increased federal income tax benefits from ITCs and PTCs at Southern Power, partially offset by the impact of additional state income tax benefits recognized in 2015 . Mississippi Power Mississippi Power's effective tax (benefit) rate was (276.2)% for the nine months ended September 30, 2016 compared to (20.9)% for the corresponding period in 2015 . The effective tax rate decrease was primarily due to an increase in tax benefits related to the estimated probable losses on construction of the Kemper IGCC and an increase in non-taxable AFUDC equity. Southern Power Southern Power's effective tax (benefit) rate was (88.9)% for the nine months ended September 30, 2016 compared to 6.9% for the corresponding period in 2015 . The effective tax rate decrease was primarily due to increased federal income tax benefits from ITCs related to solar projects expected to be placed in service in 2016 and additional PTCs related to wind projects in 2016 compared to 2015 . Unrecognized Tax Benefits See Note 5 to the financial statements of each registrant under "Unrecognized Tax Benefits" in Item 8 of the Form 10-K for additional information. Changes during 2016 for unrecognized tax benefits were as follows: Mississippi Power Southern Power Southern Company (in millions) Unrecognized tax benefits as of December 31, 2015 $ 421 $ 8 $ 433 Tax positions from current periods — 12 12 Tax positions from prior periods 18 (1 ) 13 Balance as of September 30, 2016 $ 439 $ 19 $ 458 The tax positions from current periods primarily relate to federal income tax benefits from deferred ITCs and ITCs impacting the estimated annual effective tax rate for interim reporting purposes. The tax positions from prior periods primarily relate to federal income tax benefits from ITCs, and from deductions for Kemper IGCC-related research and experimental (R&E) expenditures. See " Section 174 Research and Experimental Deduction " below for additional information. These amounts are presented on a gross basis without considering the related federal or state income tax impact. The impact on the effective tax rate, if recognized, is as follows: As of September 30, 2016 As of December 31, 2015 Mississippi Power Southern Power Southern Company Southern Company (in millions) Tax positions impacting the effective tax rate $ 1 $ 19 $ 20 $ 10 Tax positions not impacting the effective tax rate 438 — 438 423 Balance of unrecognized tax benefits $ 439 $ 19 $ 458 $ 433 The tax positions impacting the effective tax rate primarily relate to federal income tax benefits from ITCs and Southern Company's estimate of the uncertainty related to the amount of those benefits. The impact on the effective tax rate is determined based on the amount of ITCs, which is uncertain. If these tax positions are not able to be recognized due to a federal audit adjustment equal to the estimated amount, the amount of tax credit carryforwards discussed above would be reduced by approximately $94 million . Accrued interest for all tax positions other than Section 174 R&E deductions disclosed below was immaterial for all periods presented. All of the registrants classify interest on tax uncertainties as interest expense. None of the registrants accrued any penalties on uncertain tax positions. It is reasonably possible that the amount of the unrecognized tax benefits could change within 12 months . The settlement of federal and state audits could impact the balances significantly. At this time, an estimate of the range of reasonably possible outcomes cannot be determined. The IRS has finalized its audits of Southern Company's consolidated federal income tax returns through 2012. Southern Company has filed its 2013, 2014, and 2015 federal income tax returns and has received partial acceptance letters from the IRS; however, the IRS has not finalized its audits. Southern Company is a participant in the Compliance Assurance Process of the IRS. The audits for the Southern Company's state income tax returns have either been concluded, or the statute of limitations has expired, for years prior to 2011. Section 174 Research and Experimental Deduction Southern Company has reflected deductions for R&E expenditures related to the Kemper IGCC in its federal income tax calculations since 2013 and has filed amended federal income tax returns for 2008 through 2013 to also include such deductions. The Kemper IGCC is based on first-of-a-kind technology, and Southern Company and Mississippi Power believe that a significant portion of the plant costs qualify as deductible R&E expenditures under Internal Revenue Code Section 174. Subsequent to September 30, 2016, Southern Company and Mississippi Power responded to a notice of proposed assessment from the IRS, which is continuing to review the underlying support for the deduction. Due to the uncertainty related to this tax position, Southern Company and Mississippi Power had related unrecognized tax benefits associated with these R&E deductions of approximately $438 million and associated interest of $24 million as of September 30, 2016 . It is reasonably possible that this matter will be resolved in the next 12 months; however, the ultimate outcome of this matter cannot be determined at this time.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES	DERIVATIVES Southern Company, the traditional electric operating companies, Southern Power, and Southern Company Gas are exposed to market risks, including commodity price risk, interest rate risk, weather risk, and occasionally foreign currency risk. To manage the volatility attributable to these exposures, each company nets its exposures, where possible, to take advantage of natural offsets and enters into various derivative transactions for the remaining exposures pursuant to each company's policies in areas such as counterparty exposure and risk management practices. Each company's policy is that derivatives are to be used primarily for hedging purposes and mandates strict adherence to all applicable risk management policies. Derivative positions are monitored using techniques including, but not limited to, market valuation, value at risk, stress testing, and sensitivity analysis. Derivative instruments are recognized at fair value in the balance sheets as either assets or liabilities and are presented on a net basis. See Note (C) for additional information. In the statements of cash flows, the cash impacts of settled energy-related and interest rate derivatives are recorded as operating activities. The cash impacts of settled foreign currency derivatives are classified as operating or financing activities to correspond with classification of the hedged interest or principal, respectively. Energy-Related Derivatives Southern Company, the traditional electric operating companies, Southern Power, and Southern Company Gas enter into energy-related derivatives to hedge exposures to electricity, natural gas, and other fuel price changes. However, due to cost-based rate regulations and other various cost recovery mechanisms, the traditional electric operating companies and the natural gas distribution utilities of Southern Company Gas have limited exposure to market volatility in energy-related commodity prices. Each of the traditional electric operating companies and certain natural gas distribution utilities of Southern Company Gas manage fuel-hedging programs, implemented per the guidelines of their respective state PSCs or other applicable state regulatory agencies, through the use of financial derivative contracts, which is expected to continue to mitigate price volatility. The traditional electric operating companies (with respect to wholesale generating capacity), Southern Power, and Southern Company Gas have limited exposure to market volatility in energy-related commodity prices because their long-term sales contracts shift substantially all fuel cost responsibility to the purchaser. However, the traditional electric operating companies, Southern Power, and Southern Company Gas may be exposed to market volatility in energy-related commodity prices to the extent any uncontracted capacity is used to sell electricity and natural gas. Southern Company Gas uses storage and transportation capacity contracts to manage market price risks. Southern Company Gas purchases natural gas for storage when the current market price paid to buy and transport natural gas plus the cost to store and finance the natural gas is less than the market price Southern Company Gas will receive in the future, resulting in a positive net operating margin. Southern Company Gas uses New York Mercantile Exchange (NYMEX) futures and over-the-counter (OTC) contracts to sell natural gas at that future price to substantially protect the operating margin ultimately realized when the stored natural gas is sold. Southern Company Gas also enters into transactions to secure transportation capacity between delivery points in order to serve its customers and various markets. Southern Company Gas uses NYMEX futures and OTC contracts to capture the price differential between the locations served by the capacity in order to substantially protect the operating margin ultimately realized when natural gas is physically flowed between the delivery points. These contracts generally meet the definition of derivatives, but are not designated as hedges for accounting purposes. Southern Company Gas also enters into weather derivative contracts as economic hedges of operating margins in the event of warmer-than-normal weather. Exchange-traded options are carried at fair value, with changes reflected in operating revenues. Non exchange-traded options are accounted for using the intrinsic value method. Changes in the intrinsic value for non-exchange-traded contracts are reflected in the statements of income. Energy-related derivative contracts are accounted for under one of three methods: • Regulatory Hedges — Energy-related derivative contracts which are designated as regulatory hedges relate primarily to the traditional electric operating companies' and Southern Company Gas' fuel-hedging programs, where gains and losses are initially recorded as regulatory liabilities and assets, respectively, and then are included in fuel expense as the underlying fuel is used in operations and ultimately recovered through the respective fuel cost recovery clauses. • Cash Flow Hedges — Gains and losses on energy-related derivatives designated as cash flow hedges (which are mainly used to hedge anticipated purchases and sales) are initially deferred in OCI before being recognized in the statements of income in the same period as the hedged transactions are reflected in earnings. • Not Designated — Gains and losses on energy-related derivative contracts that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred. Some energy-related derivative contracts require physical delivery as opposed to financial settlement, and this type of derivative is both common and prevalent within the electric and natural gas industries. When an energy-related derivative contract is settled physically, any cumulative unrealized gain or loss is reversed and the contract price is recognized in the respective line item representing the actual price of the underlying goods being delivered. At September 30, 2016 , the net volume of energy-related derivative contracts for natural gas positions for the Southern Company system, together with the longest hedge date over which the respective entity is hedging its exposure to the variability in future cash flows for forecasted transactions and the longest non-hedge date for derivatives not designated as hedges, were as follows: Net Purchased mmBtu Longest Hedge Date Longest Non-Hedge Date (in millions) Southern Company (*) 540 2020 2022 Alabama Power 75 2020 — Georgia Power 148 2020 — Gulf Power 57 2020 — Mississippi Power 37 2020 — Southern Power 9 2017 2016 (*) Southern Company Gas' derivative instruments are comprised of both long and short natural gas positions. A long position is a contract to purchase natural gas and a short position is a contract to sell natural gas. Southern Company Gas' volume represents the net of long natural gas positions of 3.2 billion mmBtu and short natural gas positions of 2.9 billion mmBtu as of September 30, 2016. In addition to the volumes discussed in the above table, the traditional electric operating companies and Southern Power enter into physical natural gas supply contracts that provide the option to sell back excess gas due to operational constraints. The maximum expected volume of natural gas subject to such a feature is 5 million mmBtu for Southern Company and Georgia Power. For cash flow hedges, the amounts expected to be reclassified from accumulated OCI to earnings for the next 12 -month period ending September 30, 2017 are immaterial for all registrants. Interest Rate Derivatives Southern Company and certain subsidiaries may also enter into interest rate derivatives to hedge exposure to changes in interest rates. The derivatives employed as hedging instruments are structured to minimize ineffectiveness. Derivatives related to existing variable rate securities or forecasted transactions are accounted for as cash flow hedges where the effective portion of the derivatives' fair value gains or losses is recorded in OCI and is reclassified into earnings at the same time the hedged transactions affect earnings, with any ineffectiveness recorded directly to earnings. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings, providing an offset, with any difference representing ineffectiveness. Fair value gains or losses on derivatives that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred. At September 30, 2016 , the following interest rate derivatives were outstanding: Notional Amount Interest Rate Received Weighted Average Interest Rate Paid Hedge Maturity Date Fair Value (in millions) (in millions) Cash Flow Hedges of Forecasted Debt Gulf Power $ 80 3-month 2.32% December 2026 $ (6 ) Cash Flow Hedges of Existing Debt Mississippi Power 900 1-month 0.79% March 2018 (1 ) Fair Value Hedges of Existing Debt Southern Company (a) 250 1.30% 3-month August 2017 1 Southern Company (a) 300 2.75% 3-month June 2020 9 Georgia Power 250 5.40% 3-month June 2018 2 Georgia Power 200 4.25% 3-month December 2019 5 Georgia Power 500 1.95% 3-month December 2018 2 Derivatives not Designated as Hedges Southern Power 65 (b)(e) 3-month 2.50% October 2016 (f) — Southern Power 47 (c)(e) 3-month 2.21% October 2016 (f) — Southern Power 65 (d)(e) 3-month 2.21% November 2016 (g) — Southern Company Consolidated $ 2,657 $ 12 (a) Represents the Southern Company parent entity. (b) Swaption at RE Tranquillity LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (c) Swaption at RE Roserock LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. Subsequent to September 30, 2016, Roserock extended the maturity date of its swaption to December 31, 2016. (d) Swaption at RE Garland Holdings LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (e) Amortizing notional amount. (f) Represents the mandatory settlement date. Settlement will be based on a 15 -year amortizing swap. (g) Represents the mandatory settlement date. Settlement will be based on a 12 -year amortizing swap. The estimated pre-tax gains (losses) expected to be reclassified from accumulated OCI to interest expense for the next 12 -month period ending September 30, 2017 are $(21) million for Southern Company and immaterial for all other registrants. Southern Company and certain subsidiaries have deferred gains and losses that are expected to be amortized into earnings through 2046 . Foreign Currency Derivatives Southern Company and certain subsidiaries may also enter into foreign currency derivatives to hedge exposure to changes in foreign currency exchange rates, such as that arising from the issuance of debt denominated in a currency other than U.S. dollars. Derivatives related to forecasted transactions are accounted for as cash flow hedges where the effective portion of the derivatives' fair value gains or losses is recorded in OCI and is reclassified into earnings at the same time that the hedged transactions affect earnings, including currency gains or losses arising from changes in the U.S. currency exchange rates. Any ineffectiveness is recorded directly to earnings. The derivatives employed as hedging instruments are structured to minimize ineffectiveness. At September 30, 2016 , the following foreign currency derivatives were outstanding: Pay Notional Pay Rate Receive Notional Receive Rate Hedge Fair Value (in millions) (in millions) (in millions) Cash Flow Hedges of Existing Debt Southern Power $ 677 2.95% € 600 1.00% June 2022 $ (2 ) Southern Power 564 3.78% 500 1.85% June 2026 1 Total $ 1,241 € 1,100 $ (1 ) The estimated pre-tax gains (losses) that will be reclassified from accumulated OCI to earnings for the next 12 -month period ending September 30, 2017 are $(12) million for Southern Company and Southern Power. Derivative Financial Statement Presentation and Amounts Derivative contracts of Southern Company, the traditional electric operating companies, Southern Power, and Southern Company Gas are presented on a net basis in the financial statements to the extent that the contracts are subject to netting arrangements. Some of these energy-related and interest rate derivative contracts may contain certain provisions that permit intra-contract netting of derivative receivables and payables for routine billing and offsets related to events of default and settlements. At September 30, 2016 , the fair value of energy-related derivatives, interest rate derivatives, and foreign currency derivatives was reflected in the balance sheets as follows: As of September 30, 2016 Derivative Category and Balance Sheet Location Assets Liabilities (in millions) Southern Company Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ 20 $ (62 ) Other deferred charges and assets/Other deferred credits and liabilities 13 (53 ) Total derivatives designated as hedging instruments for regulatory purposes $ 33 $ (115 ) Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ 4 $ (6 ) Other deferred charges and assets/Other deferred credits and liabilities — (1 ) As of September 30, 2016 Derivative Category and Balance Sheet Location Assets Liabilities (in millions) Interest rate derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ 8 $ (7 ) Other deferred charges and assets/Other deferred credits and liabilities 11 — Foreign currency derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ — $ (24 ) Other deferred charges and assets/Other deferred credits and liabilities 23 — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 46 $ (38 ) Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ 305 $ (345 ) Other deferred charges and assets/Other deferred credits and liabilities 58 (74 ) Total derivatives not designated as hedging instruments $ 363 $ (419 ) Gross amounts of recognized assets and liabilities $ 442 $ (572 ) Gross amounts offset in the Balance Sheet (*) $ (283 ) $ 394 Net amounts of assets and liabilities presented in the Balance Sheet $ 159 $ (178 ) Alabama Power Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Liabilities from risk management activities $ 4 $ (14 ) Other deferred charges and assets/Other deferred credits and liabilities 4 (7 ) Total derivatives designated as hedging instruments for regulatory purposes $ 8 $ (21 ) Gross amounts of recognized assets and liabilities $ 8 $ (21 ) Gross amounts offset in the Balance Sheet (*) $ (7 ) $ 7 Net amounts of assets and liabilities presented in the Balance Sheet $ 1 $ (14 ) Georgia Power Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Other current liabilities $ 7 $ (5 ) Other deferred charges and assets/Other deferred credits and liabilities 8 (11 ) Total derivatives designated as hedging instruments for regulatory purposes $ 15 $ (16 ) Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets/Other current liabilities $ 5 $ — Other deferred charges and assets/Other deferred credits and liabilities 5 — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 10 $ — Gross amounts of recognized assets and liabilities $ 25 $ (16 ) Gross amounts offset in the Balance Sheet (*) $ (11 ) $ 11 Net amounts of assets and liabilities presented in the Balance Sheet $ 14 $ (5 ) As of September 30, 2016 Derivative Category and Balance Sheet Location Assets Liabilities (in millions) Gulf Power Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Liabilities from risk management activities $ 1 $ (24 ) Other deferred charges and assets/Other deferred credits and liabilities — (27 ) Total derivatives designated as hedging instruments for regulatory purposes $ 1 $ (51 ) Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets/Liabilities from risk management activities $ — $ (6 ) Gross amounts of recognized assets and liabilities $ 1 $ (57 ) Gross amounts offset in the Balance Sheet (*) $ (1 ) $ 1 Net amounts of assets and liabilities presented in the Balance Sheet $ — $ (56 ) Mississippi Power Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Other current liabilities $ — $ (13 ) Other deferred charges and assets/Other deferred credits and liabilities 1 (8 ) Total derivatives designated as hedging instruments for regulatory purposes $ 1 $ (21 ) Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets/Other current liabilities $ — $ (1 ) Gross amounts of recognized assets and liabilities $ 1 $ (22 ) Gross amounts offset in the Balance Sheet (*) $ (1 ) $ 1 Net amounts of assets and liabilities presented in the Balance Sheet $ — $ (21 ) Southern Power Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets/Other current liabilities $ 2 $ (3 ) Other deferred charges and assets/Other deferred credits and liabilities — — Foreign currency derivatives: Other current assets/Other current liabilities $ — $ (24 ) Other deferred charges and assets/Other deferred credits and liabilities 23 — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 25 $ (27 ) Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets/Other current liabilities $ 1 $ — Gross amounts of recognized assets and liabilities $ 26 $ (27 ) Gross amounts offset in the Balance Sheet (*) $ (1 ) $ 1 Net amounts of assets and liabilities presented in the Balance Sheet $ 25 $ (26 ) (*) Includes any cash/financial collateral pledged or received. At December 31, 2015, the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at December 31, 2015 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets $ 3 $ 1 $ 2 $ — $ — Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets $ 3 $ — $ — $ — $ 3 Interest rate derivatives: Other current assets 19 — 5 1 — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 22 $ — $ 5 $ 1 $ 3 Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets $ 1 $ — $ — $ — $ 1 Interest rate derivatives: Other current assets 3 — — — 3 Total derivatives not designated as hedging instruments $ 4 $ — $ — $ — $ 4 Total asset derivatives $ 29 $ 1 $ 7 $ 1 $ 7 Liability Derivatives at December 31, 2015 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Liabilities from risk management activities (*) $ 130 $ 40 $ 12 $ 49 $ 29 Other deferred credits and liabilities 87 15 3 51 18 Total derivatives designated as hedging instruments for regulatory purposes $ 217 $ 55 $ 15 $ 100 $ 47 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Liabilities from risk management activities (*) $ 2 $ — $ — $ — $ — $ 2 Interest rate derivatives: Liabilities from risk management activities 23 15 — — — — Other deferred credits and liabilities 7 — 6 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 32 $ 15 $ 6 $ — $ — $ 2 Derivatives not designated as hedging instruments Energy-related derivatives: Liabilities from risk management activities (*) $ 1 $ — $ — $ — $ — $ 1 Total liability derivatives $ 250 $ 70 $ 21 $ 100 $ 47 $ 3 (*) Georgia Power, Mississippi Power, and Southern Power include current liabilities related to derivatives in other current liabilities. In 2015, the derivative contracts of Southern Company, the traditional electric operating companies, and Southern Power are reported gross on each registrant's financial statements. Some of these energy-related and interest rate derivative contracts may contain certain provisions that permit intra-contract netting of derivative receivables and payables for routine billing and offsets related to events of default and settlements. Amounts related to energy-related derivative contracts and interest rate derivative contracts at December 31, 2015 are presented in the following table: Derivative Contracts at December 31, 2015 Fair Value Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Assets Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 7 $ 1 $ 2 $ — $ — $ 4 Gross amounts not offset in the Balance Sheet (b) (6 ) (1 ) (2 ) — — (1 ) Net energy-related derivative assets $ 1 $ — $ — $ — $ — $ 3 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 22 $ — $ 5 $ 1 $ — $ 3 Gross amounts not offset in the Balance Sheet (b) (9 ) — (4 ) — — — Net interest rate derivative assets $ 13 $ — $ 1 $ 1 $ — $ 3 Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 220 $ 55 $ 15 $ 100 $ 47 $ 3 Gross amounts not offset in the Balance Sheet (b) (6 ) (1 ) (2 ) — — (1 ) Net energy-related derivative liabilities $ 214 $ 54 $ 13 $ 100 $ 47 $ 2 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 30 $ 15 $ 6 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (9 ) — (4 ) — — — Net interest rate derivative liabilities $ 21 $ 15 $ 2 $ — $ — $ — (a) As of December 31, 2015, none of the registrants offset fair value amounts for multiple derivative instruments executed with the same counterparty in the balance sheets; therefore, gross and net amounts of derivative assets and liabilities presented in the balance sheets are the same. (b) Includes gross amounts subject to netting terms that are not offset in the balance sheets and any cash/financial collateral pledged or received. At September 30, 2016 and December 31, 2015, the pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments designated as regulatory hedging instruments and deferred were as follows: Regulatory Hedge Unrealized Gain (Loss) Recognized in the Balance Sheet at September 30, 2016 Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Energy-related derivatives: Other regulatory assets, current $ (52 ) $ (10 ) $ (2 ) $ (24 ) $ (13 ) Other regulatory assets, deferred (42 ) (4 ) (4 ) (26 ) (8 ) Other regulatory liabilities, current (a) 8 1 4 — — Other regulatory liabilities, deferred (b) 1 — 1 — — Total energy-related derivative gains (losses) $ (85 ) $ (13 ) $ (1 ) $ (50 ) $ (21 ) (a) Georgia Power includes other regulatory liabilities, current in other current liabilities. (b) Georgia Power includes other regulatory liabilities, deferred in other deferred credits and liabilities. Regulatory Hedge Unrealized Gain (Loss) Recognized in the Balance Sheet at December 31, 2015 Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Energy-related derivatives: Other regulatory assets, current $ (130 ) $ (40 ) $ (12 ) $ (49 ) $ (29 ) Other regulatory assets, deferred (87 ) (15 ) (3 ) (51 ) (18 ) Other regulatory liabilities, current (*) 3 1 2 — — Total energy-related derivative gains (losses) $ (214 ) $ (54 ) $ (13 ) $ (100 ) $ (47 ) (*) Georgia Power includes other regulatory liabilities, current in other current liabilities. For the three months ended September 30, 2016 and 2015 , the pre-tax effects of energy-related derivatives, interest rate derivatives, and foreign currency derivatives designated as cash flow hedging instruments were as follows: Derivatives in Cash Flow Hedging Relationships Gain (Loss) Recognized in OCI on Derivative (Effective Portion) Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Statements of Income Location Amount 2016 2015 2016 2015 (in millions) (in millions) Southern Company Energy-related derivatives $ — $ — Amortization $ 1 $ — Interest rate derivatives (6 ) (28 ) Interest expense, net of amounts capitalized (6 ) (2 ) Foreign currency derivatives 37 — Interest expense, net of amounts capitalized (6 ) — Other income (expense), net (*) 7 — Total $ 31 $ (28 ) $ (4 ) $ (2 ) Alabama Power Interest rate derivatives $ — $ (10 ) Interest expense, net of amounts capitalized $ (2 ) $ (1 ) Georgia Power Interest rate derivatives $ — $ (18 ) Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Southern Power Energy-related derivatives $ — $ — Amortization $ 1 $ — Foreign currency derivatives 37 — Interest expense, net of amounts capitalized (6 ) — Other income (expense), net (*) 7 — Total $ 37 $ — $ 2 $ — (*) The reclassification from accumulated OCI into other income (expense), net completely offsets currency gains and losses arising from changes in the U.S. currency exchange rates used to record the euro-denominated notes. For the nine months ended September 30, 2016 and 2015 , the pre-tax effects of energy-related derivatives, interest rate derivatives, and foreign currency derivatives designated as cash flow hedging instruments recognized in OCI and those reclassified from accumulated OCI into earnings were as follows: Derivatives in Cash Flow Gain (Loss) Gain (Loss) Reclassified from Accumulated OCI into Statements of Income Location Amount 2016 2015 2016 2015 (in millions) (in millions) Southern Company Energy-related derivatives $ (1 ) $ — Amortization $ 1 $ — Interest rate derivatives (189 ) (26 ) Interest expense, net of amounts capitalized (13 ) (7 ) Foreign currency derivatives (1 ) — Interest expense, net of amounts capitalized (7 ) — Other income (expense), net (*) (13 ) — Total $ (191 ) $ (26 ) $ (32 ) $ (7 ) Alabama Power Interest rate derivatives $ (3 ) $ (9 ) Interest expense, net of amounts capitalized $ (5 ) $ (2 ) Georgia Power Interest rate derivatives $ — $ (17 ) Interest expense, net of amounts capitalized $ (3 ) $ (3 ) Gulf Power Interest rate derivatives $ (7 ) $ — Interest expense, net of amounts capitalized $ — $ — Mississippi Power Interest rate derivatives $ (1 ) $ — Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Southern Power Energy-related derivatives $ (1 ) $ — Amortization $ 1 $ — Interest rate derivatives — — Interest expense, net of amounts capitalized (1 ) (1 ) Foreign currency derivatives (1 ) — Interest expense, net of amounts capitalized (7 ) — Other income (expense), net (*) (13 ) — Total $ (2 ) $ — $ (20 ) $ (1 ) (*) The reclassification from accumulated OCI into other income (expense), net completely offsets currency gains and losses arising from changes in the U.S. currency exchange rates used to record the euro-denominated notes. For the three and nine months ended September 30, 2016 and 2015 , the pre-tax effects of interest rate derivatives designated as fair value hedging instruments were as follows: Derivatives in Fair Value Hedging Relationships Gain (Loss) Three Months Ended September 30, Nine Months Ended September 30, Derivative Category Statements of Income Location 2016 2015 2016 2015 (in millions) (in millions) Southern Company Interest rate derivatives: Interest expense, net of amounts capitalized $ (9 ) $ 15 $ 15 $ 19 Georgia Power Interest rate derivatives: Interest expense, net of amounts capitalized $ (5 ) $ 7 $ 10 $ 9 For the three and nine months ended September 30, 2016 and 2015 , the pre-tax effects of interest rate derivatives designated as fair value hedging instruments were offset by changes to the carrying value of long-term debt. There was no material ineffectiveness recorded in earnings for any registrant for any period presented. For the three and nine months ended September 30, 2016 and 2015 , the pre-tax effects of energy-related derivatives and interest rate derivatives not designated as hedging instruments were immaterial for all registrants. Contingent Features Southern Company, the traditional electric operating companies, Southern Power, and Southern Company Gas do not have any credit arrangements that would require material changes in payment schedules or terminations as a result of a credit rating downgrade. There are certain derivatives that could require collateral, but not accelerated payment, in the event of various credit rating changes of certain Southern Company subsidiaries. At September 30, 2016 , Southern Company had $111 million of collateral posted with derivative counterparties. The amount of collateral posted with the derivative counterparties for all other registrants was immaterial. At September 30, 2016 , the fair value of derivative liabilities with contingent features was $22 million for all registrants. The maximum potential collateral requirements arising from the credit-risk-related contingent features, at a rating below BBB- and/or Baa3, were $22 million for all registrants and include certain agreements that could require collateral in the event that one or more Southern Company power pool participants or Southern Company has a credit rating change to below investment grade. Generally, collateral may be provided by a Southern Company guaranty, letter of credit, or cash. If collateral is required, fair value amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral are not offset against fair value amounts recognized for derivatives executed with the same counterparty. Southern Company, the traditional electric operating companies, Southern Power, and Southern Company Gas are exposed to losses related to financial instruments in the event of counterparties' nonperformance. Southern Company, the traditional electric operating companies, Southern Power, and Southern Company Gas only enter into agreements and material transactions with counterparties that have investment grade credit ratings by Moody's and S&P or with counterparties who have posted collateral to cover potential credit exposure. Southern Company, the traditional electric operating companies, Southern Power, and Southern Company Gas have also established risk management policies and controls to determine and monitor the creditworthiness of counterparties in order to mitigate Southern Company's, the traditional electric operating companies', Southern Power's, and Southern Company Gas' exposure to counterparty credit risk. Southern Company Gas may require counterparties to pledge additional collateral when deemed necessary. Therefore, Southern Company, the traditional electric operating companies, and Southern Power do not anticipate a material adverse effect on the financial statements as a result of counterparty nonperformance.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS Southern Company Merger with Southern Company Gas Southern Company Gas, formerly known as AGL Resources Inc., is an energy services holding company whose primary business is the distribution of natural gas through natural gas distribution utilities. On July 1, 2016, Southern Company completed the Merger for a total purchase price of approximately $8.0 billion and Southern Company Gas became a wholly-owned, direct subsidiary of Southern Company. The Merger was accounted for using the acquisition method of accounting with the assets acquired and liabilities assumed recognized at fair value as of the acquisition date. The following table presents the preliminary purchase price allocation: Southern Company Gas Purchase Price September 30, 2016 (in millions) Current assets $ 1,557 Property, plant, and equipment 10,108 Goodwill 5,937 Intangible assets 400 Regulatory assets 1,118 Other assets 229 Current liabilities (2,201 ) Other liabilities (4,712 ) Long-term debt (4,261 ) Noncontrolling interests (174 ) Total purchase price $ 8,001 The excess of the purchase price over the estimated fair values of the assets acquired and liabilities assumed of $5.9 billion is recognized as goodwill, which is primarily attributable to positioning the Southern Company system to provide natural gas infrastructure to meet customers' growing energy needs and to compete for growth across the energy value chain. Southern Company anticipates that much of the value assigned to goodwill will not be deductible for tax purposes. The estimated fair values noted above are preliminary and are subject to change upon finalization of the purchase accounting assessment as additional information related to the fair value of assets and liabilities becomes available. Subsequent adjustments to the preliminary purchase price allocation are not expected to have a material impact on the results of operations and financial position of Southern Company. The preliminary valuation of identifiable intangible assets included customer relationships, trade names, and storage and transportation contracts with estimated lives of one to 28 years . The estimated fair value measurements of identifiable intangible assets were primarily based on significant unobservable inputs (Level 3). The results of operations for Southern Company Gas have been included in the consolidated financial statements from the date of acquisition and consist of operating revenues of $543 million and net income of $4 million . The following summarized unaudited pro forma consolidated statement of earnings information assumes that the acquisition of Southern Company Gas was completed on January 1, 2015. The summarized unaudited pro forma consolidated statement of earnings information includes adjustments for (i) intercompany sales, (ii) amortization of intangible assets, (iii) adjustments to interest expense to reflect current interest rates on Southern Company Gas debt and additional interest expense associated with borrowings by Southern Company to fund the Merger, and (iv) the elimination of nonrecurring expenses associated with the Merger. For the Nine Months Ended September 30, 2016 2015 Operating revenues (in millions) $ 16,609 $ 16,865 Net income attributable to Southern Company (in millions) $ 2,369 $ 2,269 Basic EPS $ 2.50 $ 2.43 Diluted EPS $ 2.48 $ 2.42 These unaudited pro forma results are for comparative purposes only and may not be indicative of the results that would have occurred had this acquisition been completed on January 1, 2015 or the results that would be attained in the future. During the three and nine months ended September 30, 2016 , Southern Company recorded in its statements of income costs associated with the Merger of approximately $40.8 million and $104.1 million , respectively, of which $40.6 million and $73.5 million is included in operating expenses and $0.2 million and $30.6 million is included in other income and (expense), respectively. These costs include external transaction costs for financing, legal, and consulting services, as well as rate credits and additional compensation-related expenses. See Note 12 to the financial statements of Southern Company under "Southern Company – Proposed Merger with AGL Resources" in Item 8 of the Form 10-K for additional information. Acquisition of PowerSecure International, Inc. On May 9, 2016, Southern Company acquired all of the outstanding stock of PowerSecure, a provider of products and services in the areas of distributed generation, energy efficiency, and utility infrastructure, for $18.75 per common share in cash, resulting in an aggregate purchase price of $429 million . As a result, PowerSecure became a wholly-owned subsidiary of Southern Company. The acquisition of PowerSecure was accounted for using the acquisition method of accounting with the assets acquired and liabilities assumed recognized at fair value as of the acquisition date. The allocation of the purchase price is as follows: PowerSecure Purchase Price September 30, 2016 (in millions) Current assets $ 172 Property, plant, and equipment 46 Goodwill 284 Intangible assets 101 Other assets 6 Current liabilities (145 ) Long-term debt, including current portion (18 ) Deferred credits and other liabilities (17 ) Total purchase price $ 429 The excess of the purchase price over the estimated fair values of the assets acquired and liabilities assumed of $284 million was recognized as goodwill, which is primarily attributable to expected business expansion opportunities for PowerSecure. Southern Company anticipates that the majority of the value assigned to goodwill will not be deductible for tax purposes. The valuation of identifiable intangible assets included customer relationships, trade names, patents, backlog, and software with estimated lives of one to 26 years. The estimated fair value measurements of identifiable intangible assets were primarily based on significant unobservable inputs (Level 3). The results of operations for PowerSecure have been included in the consolidated financial statements from the date of acquisition and are immaterial to the consolidated financial results of Southern Company. Pro forma results of operations have not been presented for the acquisition because the effects of the acquisition were immaterial to Southern Company's consolidated financial results for all periods presented. Alliance with Bloom Energy Corporation O n October 24, 2016, a subsidiary of Southern Company acquired from an affiliate of Bloom Energy Corporation (Bloom) all of the equity interests of 2016 ESA HoldCo, LLC and its subsidiary, 2016 ESA Project Company, LLC. 2016 ESA Project Company, LLC expects to acquire 50 MWs of Bloom fuel cell systems to serve commercial and industrial customers under long-term PPAs. In connection with this transaction, PowerSecure and Bloom agreed to pursue a strategic alliance to develop technology for behind-the-meter energy solutions . Investment in Southern Natural Gas On July 10, 2016, Southern Company and Kinder Morgan, Inc. (Kinder Morgan) entered into a definitive agreement for Southern Company to acquire a 50% equity interest in SNG, which is the owner of a 7,000 -mile pipeline system connecting natural gas supply basins in Texas, Louisiana, Mississippi, and Alabama to markets in Louisiana, Mississippi, Alabama, Florida, Georgia, South Carolina, and Tennessee. On August 31, 2016, Southern Company assigned its rights and obligations under the definitive agreement to a wholly-owned, indirect subsidiary of Southern Company Gas. On September 1, 2016, Southern Company Gas completed the acquisition for a purchase price of approximately $1.4 billion . The investment in SNG is accounted for using the equity method. Acquisition of Remaining Interest in SouthStar SouthStar is a retail natural gas marketer and markets natural gas to residential, commercial, and industrial customers, primarily in Georgia and Illinois. At September 30, 2016, Southern Company Gas had an 85% ownership interest in SouthStar, with Piedmont owning the remaining 15% . Subsequent to September 30, 2016, Southern Company Gas purchased Piedmont's 15% interest in SouthStar for $160 million . Beginning in the fourth quarter 2016, SouthStar will be fully consolidated with Southern Company Gas. Southern Power See Note 2 to the financial statements of Southern Power and Note 12 to the financial statements of Southern Company under "Southern Power" in Item 8 of the Form 10-K for additional information. During the nine months ended September 30, 2016 , the fair values of the assets and liabilities acquired of Desert Stateline, Garland, Garland A, Lost Hills Blackwell, Morelos, North Star, Roserock, and Tranquillity were finalized with no changes to the fair values reported. During 2016 , in accordance with its overall growth strategy, Southern Power or one of its wholly-owned subsidiaries, Southern Renewable Partnerships, LLC and Southern Renewable Energy, Inc., acquired or contracted to acquire the projects discussed below. Acquisition-related costs were expensed as incurred and were not material. The acquisitions do not include any contingent consideration unless specifically noted. Project Facility Resource Seller; Acquisition Date Approximate Nameplate Capacity ( MW ) Location Southern Power Percentage Ownership Actual/Expected COD PPA Counterparties for Plant Output PPA Contract Period Acquisitions for the Nine Months Ended September 30, 2016 Calipatria Solar Solar Frontier Americas Holding LLC 20 Imperial County, CA 90 % February 2016 San Diego Gas & Electric Company 20 years East Pecos Solar First Solar, Inc. 120 Pecos County, TX 100 % December 2016 Austin Energy 15 years Grant Plains Wind Apex Clean Energy Holdings, LLC 147 Grant County, OK 100 % December 2016 Oklahoma Municipal Power Authority and Steelcase Inc. 20 years and 12 years (a) Grant Wind Wind Apex Clean Energy Holdings, LLC 151 Grant County, OK 100 % April 2016 Western Farmers, East Texas, and Northeast Texas Electric Cooperative 20 years Henrietta Solar SunPower Corp. 102 Kings County, CA 51 % (b) July 2016 Pacific Gas and Electric Company 20 years Lamesa Solar RES America Developments Inc. 102 Dawson County, TX 100 % First quarter 2017 City of Garland, Texas 15 years Passadumkeag Wind Quantum Utility Generation, LLC 42 Penobscot County, ME 100 % July 2016 Western Massachusetts Electric Company 15 years Rutherford Solar Cypress Creek Renewables, LLC 74 Rutherford County, NC 90 % December 2016 Duke Energy Carolinas, LLC 15 years Acquisitions Subsequent to September 30, 2016 Mankato Natural Gas Calpine Corporation October 26, 2016 375 (c) Mankato, MN 100 % N/A (c) Northern States Power Company 10 years Wake Wind Wind Invenergy Wind Global LLC October 26, 2016 257 Floyd and Crosby Counties, TX 90.1 % October 2016 Equinix Enterprises, Inc. and Owens Corning 12 years (a) In addition to the 20 -year and 12 -year PPAs, the facility has a 10 -year contract with Allianz Risk Transfer (Bermuda) Ltd. (b) Southern Power owns 100% of the class A membership interests and a wholly-owned subsidiary of the seller owns 100% of the class B membership interests. Southern Power and the class B member are entitled to 51% and 49% , respectively, of all cash distributions from the project. In addition, Southern Power is entitled to substantially all of the federal tax benefits with respect to the transaction. (c) The Mankato facility is a fully operational 375 -MW natural gas-fired combined-cycle facility with an additional 345 -MW expansion under development. Acquisitions During the Nine Months Ended September 30, 2016 Southern Power's aggregate purchase price for the project facilities acquired during the nine months ended September 30, 2016 was approximately $830 million , which includes $145 million of contingent consideration. Including the minority owner Turner Renewable Energy, LLC's (TRE) 10% ownership interest in Calipatria and Rutherford, SunPower Corp's 49% ownership interest in Henrietta, and the assumption of $217 million in construction debt (non-recourse to Southern Power), the total aggregate purchase price is approximately $923 million for the project facilities acquired during the nine months ended September 30, 2016 . The fair values of the assets and liabilities acquired through the business combinations were recorded as follows: $1.0 billion as CWIP, $58 million as property, plant, and equipment, $77 million as an intangible asset, $24 million as other assets, and $5 million as accounts payable; however, the allocations of the purchase price to individual assets have not been finalized. The intangible asset consists of an acquired PPA that will be amortized over its 20 -year term. The estimated amortization for future periods is approximately $1 million in 2016 and $4 million per year thereafter. For East Pecos, Grant Plains, Lamesa, and Rutherford, which are currently under construction, total aggregate construction costs, excluding the acquisition costs, are expected to be $708 million to $775 million . The ultimate outcome of these matters cannot be determined at this time. Acquisitions Subsequent to September 30, 2016 Southern Power's aggregate purchase price for acquisitions subsequent to September 30, 2016 was approximately $873 million . Including the minority owner Invenergy Wind Global LLC's 9.9% ownership interest in Wake Wind, the total aggregate purchase price is approximately $924 million . As part of Southern Power's acquisition of Mankato, which has a fully operational 375 -MW natural gas-fired combined-cycle facility, Southern Power has commenced construction of an additional 345 -MW expansion which is covered with a 20 -year PPA. Total aggregate construction costs, excluding the acquisition costs allocated to CWIP, are expected to be $170 million to $190 million . The ultimate outcome of this matter cannot be determined at this time. Acquisition Agreements Executed but Not Yet Closed During the nine months ended September 30, 2016 and subsequent to that date, Southern Power entered into agreements to acquire the following projects for an aggregate purchase price of approximately $1.2 billion : • 51% ownership interest (through 100% ownership of the class A membership interests entitling Southern Power to 51% of all cash distributions and most of the federal tax benefits) in a 100 -MW solar facility in Nevada covered with a 20 -year PPA, which is expected to close in November 2016; • 100% ownership interests in two wind facilities in Texas totaling 299 MWs, the majority of which is contracted under PPAs for the first 12 to 14 years of operation and are expected to close before the end of 2016; and • 100% ownership interest in a 275 -MW wind facility in Texas, the majority of which is contracted under a 12 -year PPA and is expected to close in January 2017. The ultimate outcome of these matters cannot be determined at this time. The aggregate amount of revenue recognized by Southern Power related to the project facilities acquired during the nine months ended September 30, 2016 included in the condensed consolidated statements of income for year-to-date 2016 is $14 million . The aggregate amount of net income, excluding impacts of ITCs and PTCs, attributable to Southern Power related to the project facilities acquired during the nine months ended September 30, 2016 included in the condensed consolidated statements of income is immaterial. These businesses did not have operating revenues or activities prior to completion of construction and their assets being placed in service; therefore, supplemental pro forma information as though the acquisitions occurred as of the beginning of 2016, and for the comparable 2015 period, is not meaningful and has been omitted. Construction Projects During the nine months ended September 30, 2016 , in accordance with its overall growth strategy, Southern Power completed construction of and placed in service, or continued construction of, the projects set forth in the following table. Through September 30, 2016 , total costs of construction incurred for the following projects were $3.0 billion , of which $1.2 billion remains in CWIP. Including the total construction costs incurred through September 30, 2016 and the acquisition prices allocated to CWIP, total aggregate construction costs for the following projects are estimated to be $3.1 billion to $3.2 billion . The ultimate outcome of these matters cannot be determined at this time. Solar Facility Seller Approximate Nameplate Capacity ( MW ) Location Actual/Expected COD PPA Counterparties for Plant Output PPA Contract Period Projects Completed During the Nine Months Ended September 30, 2016 Butler Solar Farm Strata Solar Development, LLC 22 Taylor County, GA February 2016 Georgia Power (a) 20 years Desert Stateline (b) First Solar Development, LLC 299 (c) San Bernardino County, CA Through July 2016 Southern California Edison Company (SCE) 20 years Garland A Recurrent Energy, LLC 20 Kern County, CA August 2016 SCE 20 years Pawpaw Longview Solar, LLC 30 Taylor County, GA March 2016 Georgia Power (a) 30 years Tranquillity Recurrent Energy, LLC 205 Fresno County, CA July 2016 Shell Energy North America (US), LP/SCE 18 years Projects Under Construction as of September 30, 2016 Butler CERSM, LLC and Community Energy, Inc. 103 Taylor County, GA December 2016 Georgia Power (a) 30 years Garland Recurrent Energy, LLC 185 Kern County, CA October 2016 SCE 15 years Roserock Recurrent Energy, LLC 160 Pecos County, TX November 2016 Austin Energy 20 years Sandhills N/A 146 Taylor County, GA October 2016 Cobb, Flint, Irwin, Middle Georgia and Sawnee Electric Membership Corporations 25 years (a) Affiliate PPA approved by the FERC. (b) On March 29, 2016, Southern Power acquired an additional 15% interest in Desert Stateline. As a result, Southern Power and the class B member are entitled to 66% and 34% , respectively, of all cash distributions from Desert Stateline. In addition, Southern Power will continue to be entitled to substantially all of the federal tax benefits with respect to the transaction. (c) The facility has a total of 299 MWs, of which 110 MWs were placed in service in the fourth quarter 2015 and 189 MWs were placed in service during the nine months ended September 30, 2016 .

Segment and Related Information

Segment and Related Information	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
SEGMENT AND RELATED INFORMATION	SEGMENT AND RELATED INFORMATION The primary business of the Southern Company system is electricity sales by the traditional electric operating companies and Southern Power and, as a result of closing the Merger, the distribution of natural gas by Southern Company Gas. The four traditional electric operating companies – Alabama Power, Georgia Power, Gulf Power, and Mississippi Power – are vertically integrated utilities providing electric service in four Southeastern states. Southern Power constructs, acquires, owns, and manages power generation assets, including renewable energy projects, and sells electricity at market-based rates in the wholesale market. Southern Company Gas is an energy services holding company whose primary business is the distribution of natural gas through seven natural gas distribution utilities and is involved in several other complementary businesses including gas marketing services, wholesale gas services, and gas midstream operations. Southern Company's reportable business segments are the sale of electricity by the four traditional electric operating companies, the sale of electricity in the competitive wholesale market by Southern Power, and the sale of natural gas and other products and services by Southern Company Gas. Revenues from sales by Southern Power to the traditional electric operating companies were $110 million and $313 million for the three and nine months ended September 30, 2016 , respectively, and $104 million and $303 million for the three and nine months ended September 30, 2015 , respectively. The "All Other" column includes the Southern Company parent entity, which does not allocate operating expenses to business segments. Also, this category includes segments below the quantitative threshold for separate disclosure. These segments include products and services in the areas of distributed generation, energy efficiency, and utility infrastructure, as well as investments in telecommunications and leveraged lease projects. All other inter-segment revenues are not material. Financial data for business segments and products and services for the three and nine months ended September 30, 2016 and 2015 was as follows: Electric Utilities Traditional Electric Operating Companies Southern Power Eliminations Total Southern Company Gas All Other Eliminations Consolidated (in millions) Three Months Ended Operating revenues $ 5,236 $ 500 $ (117 ) $ 5,619 $ 543 $ 139 $ (37 ) $ 6,264 Segment net income (loss) (a)(b) 1,018 176 — 1,194 4 (67 ) (1 ) 1,130 Nine Months Ended Operating revenues $ 13,120 $ 1,189 $ (330 ) $ 13,979 $ 543 $ 311 $ (118 ) $ 14,715 Segment net income (loss) (a)(c) 2,076 315 — 2,391 4 (161 ) (8 ) 2,226 Total assets at September 30, 2016 $ 71,448 $ 12,351 $ (440 ) $ 83,359 $ 21,185 $ 2,974 $ (1,156 ) $ 106,362 Three Months Ended Operating revenues $ 5,098 $ 401 $ (109 ) $ 5,390 $ — $ 37 $ (26 ) $ 5,401 Segment net income (loss) (a)(b) 874 102 — 976 — (18 ) 1 959 Nine Months Ended Operating revenues $ 13,123 $ 1,086 $ (322 ) $ 13,887 $ — $ 120 $ (86 ) $ 13,921 Segment net income (loss) (a)(c) 1,912 181 — 2,093 — 3 — 2,096 Total assets at December 31, 2015 $ 69,052 $ 8,905 $ (397 ) $ 77,560 $ — $ 1,819 $ (1,061 ) $ 78,318 (a) Attributable to Southern Company. (b) Segment net income (loss) for the traditional electric operating companies includes pre-tax charges for estimated probable losses on the Kemper IGCC of $88 million ( $54 million after tax) and $150 million ( $93 million after tax) for the three months ended September 30, 2016 and 2015 , respectively. See Note (B) under " Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate " for additional information. (c) Segment net income (loss) for the traditional electric operating companies includes pre-tax charges for estimated probable losses on the Kemper IGCC of $222 million ( $137 million after tax) and $182 million ( $112 million after tax) for the nine months ended September 30, 2016 and 2015 , respectively. See Note (B) under " Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate " for additional information. Products and Services Electric Utilities' Revenues Period Retail Wholesale Other Total (in millions) Three Months Ended September 30, 2016 $ 4,808 $ 613 $ 198 $ 5,619 Three Months Ended September 30, 2015 4,701 520 169 5,390 Nine Months Ended September 30, 2016 $ 11,932 $ 1,455 $ 592 $ 13,979 Nine Months Ended September 30, 2015 11,958 1,435 494 13,887 Southern Company Gas' Revenues Period Gas Gas All Other Total (in millions) Three and Nine Months Ended September 30, 2016 $ 420 $ 126 $ (3 ) $ 543

Introduction (Policies)

Introduction (Policies)	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting	The condensed quarterly financial statements of each registrant included herein have been prepared by such registrant, without audit, pursuant to the rules and regulations of the SEC. The Condensed Balance Sheets as of December 31, 2015 have been derived from the audited financial statements of each registrant. In the opinion of each registrant's management, the information regarding such registrant furnished herein reflects all adjustments, which, except as otherwise disclosed, are of a normal recurring nature, necessary to present fairly the results of operations for the periods ended September 30, 2016 and 2015 . Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, although each registrant believes that the disclosures regarding such registrant are adequate to make the information presented not misleading. Disclosures which would substantially duplicate the disclosures in the Form 10-K and details which have not changed significantly in amount or composition since the filing of the Form 10-K are generally omitted from this Quarterly Report on Form 10-Q unless specifically required by GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K. Due to the seasonal variations in the demand for energy, operating results for the periods presented are not necessarily indicative of the operating results to be expected for the full year.
Reclassification	Certain prior year data presented in the financial statements have been reclassified to conform to the current year presentation. These reclassifications had no impact on the results of operations, financial position, or cash flows of any registrant.
Recently Issued Accounting Standards	Recently Issued Accounting Standards On February 25, 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 requires lessees to recognize on the balance sheet a lease liability and a right-of-use asset for all leases. ASU 2016-02 also changes the recognition, measurement, and presentation of expense associated with leases and provides clarification regarding the identification of certain components of contracts that would represent a lease. The accounting required by lessors is relatively unchanged and there is no change to the accounting for existing leveraged leases. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The registrants are currently evaluating the new standard and have not yet determined its ultimate impact; however, adoption of ASU 2016-02 is expected to have a significant impact on the registrants' balance sheets. On March 30, 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). ASU 2016-09 changes the accounting for income taxes and the cash flow presentation for share-based payment award transactions. Most significantly, entities are required to recognize all excess tax benefits and deficiencies related to the exercise or vesting of stock compensation as income tax expense or benefit in the income statement. Southern Company and the traditional electric operating companies currently recognize any excess tax benefits and deficiencies related to the exercise and vesting of stock compensation as additional paid-in capital. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016. Early adoption is permitted and Southern Company and the traditional electric operating companies intend to adopt the ASU in the fourth quarter 2016. The adoption is not expected to have a material impact on the results of operations, financial position, or cash flows of Southern Company and the traditional electric operating companies.
Asset Retirement Obligations	The cost estimates below are based on information as of September 30, 2016 . The cost estimates for AROs related to the disposal of CCR are based on various assumptions related to closure and post-closure costs, timing of future cash outlays, inflation and discount rates, and the potential methods for complying with the Disposal of Coal Combustion Residuals from Electric Utilities final rule requirements for closure in place or by other methods. As further analysis is performed, including evaluation of the expected method of compliance, refinement of assumptions underlying the cost estimates, such as the quantities of CCR at each site, and the determination of timing, including the potential for closing ash ponds prior to the end of their currently anticipated useful life, the traditional electric operating companies expect to continue to periodically update these estimates. As of September 30, 2016 , details of the AROs included in the registrants' Condensed Balance Sheets were as follows: Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Balance at beginning of year $ 3,759 $ 1,448 $ 1,916 $ 130 $ 177 $ 21 Liabilities incurred 41 5 — — 15 18 Liabilities settled (117 ) (12 ) (93 ) — (12 ) — Accretion 119 55 56 2 3 1 Cash flow revisions 712 31 675 2 7 — Balance at end of period $ 4,514 $ 1,527 $ 2,554 $ 134 $ 190 $ 40 The traditional electric operating companies' increases in cash flow revisions for the nine months ended September 30, 2016 primarily relate to changes in ash pond closure strategy. The increase for Georgia Power reflects its decision in June 2016 to cease operating and stop receiving coal ash at all of its ash ponds within the next three years and to eventually close all of its ash ponds either by removal, consolidation, and/or recycling for the beneficial use of coal ash or through closure in place using advanced engineering methods.
Valuation Methodologies	Valuation Methodologies The energy-related derivatives primarily consist of exchange-traded and over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and occasionally, implied volatility of interest rate options. The fair value of cross-currency swaps reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future foreign currency exchange rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and discount rates. The interest rate derivatives and cross-currency swaps are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note (H) for additional information on how these derivatives are used. The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. For fair value measurements of the investments within the nuclear decommissioning trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available. See Note 1 to the financial statements of Southern Company, Alabama Power, and Georgia Power under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information. Southern Power has contingent payment obligations related to certain acquisitions whereby Southern Power is obligated to pay generation-based payments to the seller over a 10 -year period beginning at the commercial operation date. The obligation is measured at fair value using significant inputs such as forecasted facility generation in MW-hours, a fixed dollar amount per MW-hour, and a discount rate, and is evaluated periodically. The fair value of contingent consideration reflects the net present value of expected payments and any change arising from forecasted generation is expected to be immaterial. "Other investments" include investments that are not traded in the open market. The fair value of these investments have been determined based on market factors including comparable multiples and the expectations regarding cash flows and business plan executions.
Earnings per Share	Earnings per Share For Southern Company, the only difference in computing basic and diluted earnings per share is attributable to awards outstanding under the stock option and performance share plans. See Note 8 to the financial statements of Southern Company in Item 8 of the Form 10-K for information on the stock option and performance share plans. The effect of both stock options and performance share award units was determined using the treasury stock method.
Energy-Related Derivatives and Interest Rate Derivatives	Southern Company, the traditional electric operating companies, Southern Power, and Southern Company Gas are exposed to market risks, including commodity price risk, interest rate risk, weather risk, and occasionally foreign currency risk. To manage the volatility attributable to these exposures, each company nets its exposures, where possible, to take advantage of natural offsets and enters into various derivative transactions for the remaining exposures pursuant to each company's policies in areas such as counterparty exposure and risk management practices. Each company's policy is that derivatives are to be used primarily for hedging purposes and mandates strict adherence to all applicable risk management policies. Derivative positions are monitored using techniques including, but not limited to, market valuation, value at risk, stress testing, and sensitivity analysis. Derivative instruments are recognized at fair value in the balance sheets as either assets or liabilities and are presented on a net basis. See Note (C) for additional information. In the statements of cash flows, the cash impacts of settled energy-related and interest rate derivatives are recorded as operating activities. The cash impacts of settled foreign currency derivatives are classified as operating or financing activities to correspond with classification of the hedged interest or principal, respectively. Energy-Related Derivatives Southern Company, the traditional electric operating companies, Southern Power, and Southern Company Gas enter into energy-related derivatives to hedge exposures to electricity, natural gas, and other fuel price changes. However, due to cost-based rate regulations and other various cost recovery mechanisms, the traditional electric operating companies and the natural gas distribution utilities of Southern Company Gas have limited exposure to market volatility in energy-related commodity prices. Each of the traditional electric operating companies and certain natural gas distribution utilities of Southern Company Gas manage fuel-hedging programs, implemented per the guidelines of their respective state PSCs or other applicable state regulatory agencies, through the use of financial derivative contracts, which is expected to continue to mitigate price volatility. The traditional electric operating companies (with respect to wholesale generating capacity), Southern Power, and Southern Company Gas have limited exposure to market volatility in energy-related commodity prices because their long-term sales contracts shift substantially all fuel cost responsibility to the purchaser. However, the traditional electric operating companies, Southern Power, and Southern Company Gas may be exposed to market volatility in energy-related commodity prices to the extent any uncontracted capacity is used to sell electricity and natural gas. Southern Company Gas uses storage and transportation capacity contracts to manage market price risks. Southern Company Gas purchases natural gas for storage when the current market price paid to buy and transport natural gas plus the cost to store and finance the natural gas is less than the market price Southern Company Gas will receive in the future, resulting in a positive net operating margin. Southern Company Gas uses New York Mercantile Exchange (NYMEX) futures and over-the-counter (OTC) contracts to sell natural gas at that future price to substantially protect the operating margin ultimately realized when the stored natural gas is sold. Southern Company Gas also enters into transactions to secure transportation capacity between delivery points in order to serve its customers and various markets. Southern Company Gas uses NYMEX futures and OTC contracts to capture the price differential between the locations served by the capacity in order to substantially protect the operating margin ultimately realized when natural gas is physically flowed between the delivery points. These contracts generally meet the definition of derivatives, but are not designated as hedges for accounting purposes. Southern Company Gas also enters into weather derivative contracts as economic hedges of operating margins in the event of warmer-than-normal weather. Exchange-traded options are carried at fair value, with changes reflected in operating revenues. Non exchange-traded options are accounted for using the intrinsic value method. Changes in the intrinsic value for non-exchange-traded contracts are reflected in the statements of income. Energy-related derivative contracts are accounted for under one of three methods: • Regulatory Hedges — Energy-related derivative contracts which are designated as regulatory hedges relate primarily to the traditional electric operating companies' and Southern Company Gas' fuel-hedging programs, where gains and losses are initially recorded as regulatory liabilities and assets, respectively, and then are included in fuel expense as the underlying fuel is used in operations and ultimately recovered through the respective fuel cost recovery clauses. • Cash Flow Hedges — Gains and losses on energy-related derivatives designated as cash flow hedges (which are mainly used to hedge anticipated purchases and sales) are initially deferred in OCI before being recognized in the statements of income in the same period as the hedged transactions are reflected in earnings. • Not Designated — Gains and losses on energy-related derivative contracts that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred. Some energy-related derivative contracts require physical delivery as opposed to financial settlement, and this type of derivative is both common and prevalent within the electric and natural gas industries. When an energy-related derivative contract is settled physically, any cumulative unrealized gain or loss is reversed and the contract price is recognized in the respective line item representing the actual price of the underlying goods being delivered. Interest Rate Derivatives Southern Company and certain subsidiaries may also enter into interest rate derivatives to hedge exposure to changes in interest rates. The derivatives employed as hedging instruments are structured to minimize ineffectiveness. Derivatives related to existing variable rate securities or forecasted transactions are accounted for as cash flow hedges where the effective portion of the derivatives' fair value gains or losses is recorded in OCI and is reclassified into earnings at the same time the hedged transactions affect earnings, with any ineffectiveness recorded directly to earnings. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings, providing an offset, with any difference representing ineffectiveness. Fair value gains or losses on derivatives that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred.

Introduction (Tables)

Introduction (Tables)	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Asset Retirement Obligations	As of September 30, 2016 , details of the AROs included in the registrants' Condensed Balance Sheets were as follows: Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Balance at beginning of year $ 3,759 $ 1,448 $ 1,916 $ 130 $ 177 $ 21 Liabilities incurred 41 5 — — 15 18 Liabilities settled (117 ) (12 ) (93 ) — (12 ) — Accretion 119 55 56 2 3 1 Cash flow revisions 712 31 675 2 7 — Balance at end of period $ 4,514 $ 1,527 $ 2,554 $ 134 $ 190 $ 40
Schedule of Goodwill	As of September 30, 2016, goodwill was as follows: As of September 30, 2016 (in millions) Southern Company $ 6,223 Southern Power $ 2
Schedule of Goodwill and Other Intangible Assets	As of September 30, 2016, other intangible assets were as follows: As of September 30, 2016 Estimated Useful Life Gross Carrying Amount Accumulated Amortization Other Intangible Assets, Net (in millions) Southern Company Other intangible assets subject to amortization: Customer relationships 11-26 years $ 268 $ (16 ) $ 252 Trade names 5-28 years 158 (3 ) 155 Patents 3-10 years 4 — 4 Backlog 5 years 5 — 5 Storage and transportation contracts 1-5 years 64 (4 ) 60 Software and other 1-12 years 2 — 2 PPA fair value adjustments 19-20 years 405 (16 ) 389 Total other intangible assets subject to amortization $ 906 $ (39 ) $ 867 Other intangible assets not subject to amortization: Federal Communications Commission licenses $ 75 $ — $ 75 Total other intangible assets $ 981 $ (39 ) $ 942 Southern Power Other intangible assets subject to amortization: PPA fair value adjustments 19-20 years $ 405 $ (16 ) $ 389
Finite-lived Intangible Assets Amortization Expense	Amortization associated with other intangible assets was as follows: Three Months Ended Nine Months Ended September 30, 2016 (in millions) Southern Company $ 25 $ 27 Southern Power $ 2 $ 4

Contingencies and Regulatory 21

Contingencies and Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Recovery Balance of Each Regulatory Clause	The balance of each regulatory clause recovery on the balance sheet follows: Regulatory Clause Balance Sheet Line Item September 30, December 31, 2015 (in millions) Rate CNP Compliance Under recovered regulatory clause revenues $ — $ 43 Deferred over recovered regulatory clause revenues 23 — Rate CNP PPA Under recovered regulatory clause revenues 52 99 Deferred under recovered regulatory clause revenues 87 — Retail Energy Cost Recovery Other regulatory liabilities, current — 238 Deferred over recovered regulatory clause revenues 134 — Natural Disaster Reserve Other regulatory liabilities, deferred 71 75 The balance of each regulatory clause recovery on the balance sheet follows: Regulatory Clause Balance Sheet Line Item September 30, December 31, 2015 (in millions) Fuel Cost Recovery Other regulatory liabilities, current $ 20 $ 18 Purchased Power Capacity Recovery Other regulatory liabilities, current 3 — Purchased Power Capacity Recovery Under recovered regulatory clause revenues — 1 Environmental Cost Recovery Other regulatory liabilities, current 5 — Environmental Cost Recovery Under recovered regulatory clause revenues — 19 Energy Conservation Cost Recovery Other regulatory liabilities, current — 4 Energy Conservation Cost Recovery Under recovered regulatory clause revenues 2 —
Current And Actual Cost Estimate for Kemper IGCC	Mississippi Power's Kemper IGCC 2010 project estimate, current cost estimate (which includes the impacts of the Mississippi Supreme Court's (Court) decision discussed herein under "Rate Recovery of Kemper IGCC Costs – 2013 MPSC Rate Order"), and actual costs incurred as of September 30, 2016 are as follows: Cost Category 2010 Project Estimate (a) Current Cost Estimate (b) Actual Costs (in billions) Plant Subject to Cost Cap (c)(e) $ 2.40 $ 5.52 $ 5.30 Lignite Mine and Equipment 0.21 0.23 0.23 CO 2 Pipeline Facilities 0.14 0.11 0.11 AFUDC (d) 0.17 0.75 0.71 Combined Cycle and Related Assets Placed in (e) — 0.04 0.03 General Exceptions 0.05 0.10 0.09 Deferred Costs (e) — 0.21 0.20 Additional DOE Grants (f) — (0.14 ) (0.14 ) Total Kemper IGCC $ 2.97 $ 6.82 $ 6.53 (a) The 2010 Project Estimate is the certificated cost estimate adjusted to include the certificated estimate for the CO 2 pipeline facilities approved in 2011 by the Mississippi PSC, as well as the lignite mine and equipment, AFUDC, and general exceptions. (b) Amounts in the Current Cost Estimate include certain estimated post-in-service costs which are expected to be subject to the cost cap. (c) The 2012 MPSC CPCN Order approved a construction cost cap of up to $2.88 billion , net of the Initial DOE Grants and excluding the Cost Cap Exceptions. The Current Cost Estimate and the Actual Costs include non-incremental operating and maintenance costs related to the combined cycle and associated common facilities placed in service in August 2014 that are subject to the $2.88 billion cost cap and exclude post-in-service costs for the lignite mine. See " Rate Recovery of Kemper IGCC Costs – 2013 MPSC Rate Order " herein for additional information. The Current Cost Estimate and the Actual Costs reflect 100% of the costs of the Kemper IGCC. See note (e) for additional information. (d) Mississippi Power's 2010 Project Estimate included recovery of financing costs during construction rather than the accrual of AFUDC. This approach was not approved by the Mississippi PSC as described in " Rate Recovery of Kemper IGCC Costs – 2013 MPSC Rate Order ." The Current Cost Estimate also reflects the impact of a settlement agreement with the wholesale customers for cost-based rates under FERC's jurisdiction. See " FERC Matters " herein for additional information. (e) Non-capital Kemper IGCC-related costs incurred during construction were initially deferred as regulatory assets. Some of these costs are now included in rates and are being recognized through income; however, such costs continue to be included in the Current Cost Estimate and the Actual Costs at September 30, 2016 . The wholesale portion of debt carrying costs, whether deferred or recognized through income, is not included in the Current Cost Estimate and the Actual Costs at September 30, 2016 . See " Rate Recovery of Kemper IGCC Costs – Regulatory Assets and Liabilities " herein for additional information. (f) On April 8, 2016, Mississippi Power received approximately $137 million in additional grants from the DOE for the Kemper IGCC (Additional DOE Grants), which are expected to be used to reduce future rate impacts for customers.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value on a recurring basis	As of September 30, 2016 , assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows: Fair Value Measurements Using As of September 30, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Southern Company Assets: Energy-related derivatives (a) $ 203 $ 190 $ — $ — $ 393 Interest rate derivatives — 19 — — 19 Foreign currency derivatives — 23 — — 23 Nuclear decommissioning trusts (b) 660 938 — 18 1,616 Cash equivalents 1,680 — — — 1,680 Other investments 9 — 1 — 10 Total $ 2,552 $ 1,170 $ 1 $ 18 $ 3,741 Liabilities: Energy-related derivatives $ 267 $ 274 $ — $ — $ 541 Interest rate derivatives — 7 — — 7 Foreign currency derivatives — 24 — — 24 Contingent consideration — — 18 — 18 Total $ 267 $ 305 $ 18 $ — $ 590 Alabama Power Assets: Energy-related derivatives $ — $ 8 $ — $ — $ 8 Nuclear decommissioning trusts (c) Domestic equity 373 72 — — 445 Foreign equity 49 49 — — 98 U.S. Treasury and government agency securities — 22 — — 22 Corporate bonds 22 148 — — 170 Mortgage and asset backed securities — 21 — — 21 Private Equity — — — 18 18 Other — 7 — — 7 Cash equivalents 410 — — — 410 Total $ 854 $ 327 $ — $ 18 $ 1,199 Liabilities: Energy-related derivatives $ — $ 21 $ — $ — $ 21 Fair Value Measurements Using As of September 30, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Georgia Power Assets: Energy-related derivatives $ — $ 15 $ — $ — $ 15 Interest rate derivatives — 10 — — 10 Nuclear decommissioning trusts (c) (d) Domestic equity 197 1 — — 198 Foreign equity — 125 — 125 U.S. Treasury and government agency securities — 59 — — 59 Municipal bonds — 70 — — 70 Corporate bonds — 172 — — 172 Mortgage and asset backed securities — 149 — — 149 Other 19 43 — — 62 Cash equivalents 32 — — — 32 Total $ 248 $ 644 $ — $ — $ 892 Liabilities: Energy-related derivatives $ — $ 16 $ — $ — $ 16 Gulf Power Assets: Energy-related derivatives $ — $ 1 $ — $ — $ 1 Cash equivalents 20 — — — 20 Total $ 20 $ 1 $ — $ — $ 21 Liabilities: Energy-related derivatives $ — $ 51 $ — $ — $ 51 Interest rate derivatives — 6 — — 6 Total $ — $ 57 $ — $ — $ 57 Mississippi Power Assets: Energy-related derivatives $ — $ 1 $ — $ — $ 1 Cash equivalents 137 — — — 137 Total $ 137 $ 1 $ — $ — $ 138 Liabilities: Energy-related derivatives $ — $ 21 $ — $ — $ 21 Interest rate derivatives — 1 — — 1 Total $ — $ 22 $ — $ — $ 22 Fair Value Measurements Using As of September 30, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Southern Power Assets: Energy-related derivatives $ — $ 3 $ — $ — $ 3 Foreign currency derivatives — 23 — — 23 Cash equivalents 647 — — — 647 Total $ 647 $ 26 $ — $ — $ 673 Liabilities: Energy-related derivatives $ — $ 3 $ — $ — $ 3 Foreign currency derivatives — 24 — — 24 Contingent consideration — — 18 — 18 Total $ — $ 27 $ 18 $ — $ 45 (a) Excludes $7 million associated with certain weather derivatives accounted for based on intrinsic value rather than fair value. (b) For additional detail, see the nuclear decommissioning trusts sections for Alabama Power and Georgia Power in this table. (c) Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. (d) Includes the investment securities pledged to creditors and collateral received and excludes payables related to the securities lending program. As of September 30, 2016 , approximately $42 million of the fair market value of Georgia Power's nuclear decommissioning trust funds' securities were on loan to creditors under the funds' managers' securities lending program.
Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments	As of September 30, 2016 , the fair value measurements of private equity investments held in the nuclear decommissioning trust that are calculated at net asset value per share (or its equivalent) as a practical expedient, as well as the nature and risks of those investments, were as follows: As of September 30, 2016: Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period (in millions) Southern Company $ 18 $ 27 Not Applicable Not Applicable Alabama Power $ 18 $ 27 Not Applicable Not Applicable
Financial instruments for which carrying amount did not equal fair value	As of September 30, 2016 , other financial instruments for which the carrying amount did not equal fair value were as follows: Carrying Amount Fair Value (in millions) Long-term debt, including securities due within one year: Southern Company $ 43,668 $ 47,227 Alabama Power $ 7,091 $ 7,961 Georgia Power $ 10,398 $ 11,582 Gulf Power $ 1,184 $ 1,267 Mississippi Power $ 2,981 $ 2,967 Southern Power $ 4,608 $ 4,821

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Earnings per Share	Shares used to compute diluted earnings per share were as follows: Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 (in millions) As reported shares 968 910 940 910 Effect of options and performance share award units 7 2 5 3 Diluted shares 975 912 945 913
Changes in Stockholders' Equity	The following table presents year-to-date changes in stockholders' equity of Southern Company: Number of Common Shares Common Preferred and Preference Stock of Subsidiaries Total Issued Treasury Noncontrolling Interests (*) (in thousands) (in millions) Balance at December 31, 2015 915,073 (3,352 ) $ 20,592 $ 609 $ 781 $ 21,982 Consolidated net income attributable to Southern Company — — 2,226 — — 2,226 Other comprehensive income (loss) — — (95 ) — — (95 ) Stock issued 65,725 2,599 3,265 — — 3,265 Stock-based compensation — — 119 — — 119 Cash dividends on common stock — — (1,553 ) — — (1,553 ) Contributions from noncontrolling interests — — — — 357 357 Distributions to noncontrolling interests — — — — (21 ) (21 ) Purchase of membership interests from noncontrolling interests — — — — (129 ) (129 ) Net income attributable to noncontrolling interests — — — — 36 36 Other — (46 ) (7 ) — — (7 ) Balance at September 30, 2016 980,798 (799 ) $ 24,547 $ 609 $ 1,024 $ 26,180 Balance at December 31, 2014 908,502 (725 ) $ 19,949 $ 756 $ 221 $ 20,926 Consolidated net income attributable to Southern Company — — 2,096 — — 2,096 Other comprehensive income (loss) — — (7 ) — — (7 ) Stock issued 3,769 — 136 — — 136 Stock-based compensation — — 78 — — 78 Stock repurchased, at cost — (2,599 ) (115 ) — — (115 ) Cash dividends on common stock — — (1,465 ) — — (1,465 ) Preference stock redemption — — — (150 ) — (150 ) Contributions from noncontrolling interests — — — — 429 429 Distributions to noncontrolling interests — — — — (13 ) (13 ) Net income attributable to noncontrolling interests — — — — 13 13 Other — (8 ) (8 ) 3 — (5 ) Balance at September 30, 2015 912,271 (3,332 ) $ 20,664 $ 609 $ 650 $ 21,923 (*) Primarily related to Southern Power Company and excludes redeemable noncontrolling interests. See Note 10 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information.

Financing (Tables)

Financing (Tables)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Credit arrangements by company	The table below summarizes each Project Credit Facility as of September 30, 2016 . Project Maturity Date Construction Loan Facility Bridge Loan Facility Total Loan Facility Loan Facility Undrawn Letter of Credit Facility Letter of Credit Facility Undrawn (in millions) Garland Earlier of PPA COD or November 30, 2016 $ 86 $ 308 $ 394 $ 21 $ 49 $ 23 Roserock Earlier of PPA COD or November 30, 2016 (*) 63 180 243 34 23 16 Tranquillity October 14, 2016 86 172 258 12 77 26 Total $ 235 $ 660 $ 895 $ 67 $ 149 $ 65 (*) Subsequent to September 30, 2016, Roserock extended the maturity date of its Project Credit Facility to December 31, 2016. The following table outlines the committed credit arrangements by company as of September 30, 2016 : Expires Executable Term Loans Due Within One Year Company 2016 2017 2018 2020 Total Unused One Year Two Years Term Out No Term Out (in millions) (in millions) (in millions) (in millions) Southern Company (a) $ — $ — $ 1,000 $ 1,250 $ 2,250 $ 2,250 $ — $ — $ — $ — Alabama Power — 35 500 800 1,335 1,335 — — — 35 Georgia Power — — — 1,750 1,750 1,732 — — — — Gulf Power 50 65 165 — 280 280 45 — 45 70 Mississippi Power 100 75 — — 175 150 — 15 15 160 Southern Power Company (b) — — — 600 600 532 — — — — Southern Company Gas (c) — 75 1,925 — 2,000 1,947 — — — — Other — 55 — — 55 55 20 — 20 35 Southern Company Consolidated $ 150 $ 305 $ 3,590 $ 4,400 $ 8,445 $ 8,281 $ 65 $ 15 $ 80 $ 300 (a) Represents the Southern Company parent entity. (b) Excluding its subsidiaries. See " Southern Power Project Credit Facilities " below and Note (I) under " Southern Power " for additional information. (c) Southern Company Gas guarantees the obligations of Southern Company Gas Capital, which is the borrower of $1.3 billion of these arrangements. Southern Company Gas' committed credit arrangements also include $700 million restricted for working capital needs of Nicor Gas.
Schedule of Long-term Debt Financing Activities	The following table outlines the long-term debt financing activities for Southern Company and its subsidiaries for the first nine months of 2016 : Company Senior Note Issuances Senior Note Maturities and Redemptions Revenue Other Long-Term Debt Issuances Other Long-Term Debt Redemptions and Maturities (a) (in millions) Southern Company (b) $ 8,500 $ 500 $ — $ 800 $ — Alabama Power 400 200 — 45 — Georgia Power 650 700 4 300 5 Gulf Power — 125 — 2 — Mississippi Power — — — 1,100 652 Southern Power 1,531 — — 63 84 Southern Company Gas (c) 900 300 — — — Other — — — — 60 Elimination (d) — — — (200 ) (225 ) Southern Company Consolidated $ 11,981 $ 1,825 $ 4 $ 2,110 $ 576 (a) Includes reductions in capital lease obligations resulting from cash payments under capital leases. (b) Represents the Southern Company parent entity. (c) Reflects only long-term debt financing activities occurring subsequent to completion of the Merger. The senior notes were issued by Southern Company Gas Capital and guaranteed by Southern Company Gas. (d) Intercompany loans from Southern Company to Mississippi Power eliminated in Southern Company's Consolidated Financial Statements.

Retirement Benefits (Tables)

Retirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Pension Plans and Postretirement Plans	Components of the net periodic benefit costs for the three and nine months ended September 30, 2016 and 2015 were as follows: Pension Plans Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Three Months Ended September 30, 2016 Service cost $ 68 $ 14 $ 17 $ 3 $ 3 Interest cost 110 23 34 5 4 Expected return on plan assets (203 ) (46 ) (64 ) (9 ) (9 ) Amortization: Prior service costs 3 1 1 — 1 Net (gain)/loss 45 10 14 2 2 Net periodic pension cost $ 23 $ 2 $ 2 $ 1 $ 1 Nine Months Ended September 30, 2016 Service cost $ 192 $ 43 $ 52 $ 9 $ 9 Interest cost 311 71 102 14 14 Expected return on plan assets (577 ) (138 ) (193 ) (26 ) (26 ) Amortization: Prior service costs 10 2 4 1 1 Net (gain)/loss 120 30 41 5 5 Net periodic pension cost $ 56 $ 8 $ 6 $ 3 $ 3 Three Months Ended September 30, 2015 Service cost $ 65 $ 14 $ 18 $ 3 $ 3 Interest cost 111 26 38 5 5 Expected return on plan assets (181 ) (44 ) (62 ) (8 ) (8 ) Amortization: Prior service costs 6 2 2 1 — Net (gain)/loss 53 14 19 2 3 Net periodic pension cost $ 54 $ 12 $ 15 $ 3 $ 3 Nine Months Ended September 30, 2015 Service cost $ 193 $ 44 $ 54 $ 9 $ 9 Interest cost 333 79 115 15 16 Expected return on plan assets (543 ) (133 ) (188 ) (24 ) (25 ) Amortization: Prior service costs 19 5 7 1 1 Net (gain)/loss 161 41 57 7 8 Net periodic pension cost $ 163 $ 36 $ 45 $ 8 $ 9 Postretirement Benefits Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Three Months Ended September 30, 2016 Service cost $ 6 $ 1 $ 2 $ — $ — Interest cost 20 5 7 1 — Expected return on plan assets (16 ) (6 ) (6 ) — — Amortization: Prior service costs 1 1 — — — Net (gain)/loss 5 — 3 — 1 Net periodic postretirement benefit cost $ 16 $ 1 $ 6 $ 1 $ 1 Nine Months Ended September 30, 2016 Service cost $ 17 $ 4 $ 5 $ 1 $ 1 Interest cost 55 14 22 2 2 Expected return on plan assets (44 ) (19 ) (17 ) (1 ) (1 ) Amortization: Prior service costs 4 3 1 — — Net (gain)/loss 12 1 7 — 1 Net periodic postretirement benefit cost $ 44 $ 3 $ 18 $ 2 $ 3 Three Months Ended September 30, 2015 Service cost $ 6 $ 1 $ 2 $ 1 $ — Interest cost 20 5 9 — 1 Expected return on plan assets (15 ) (6 ) (6 ) — — Amortization: Prior service costs 1 2 — — — Net (gain)/loss 4 — 2 — — Net periodic postretirement benefit cost $ 16 $ 2 $ 7 $ 1 $ 1 Nine Months Ended September 30, 2015 Service cost $ 17 $ 4 $ 5 $ 1 $ 1 Interest cost 59 15 26 2 3 Expected return on plan assets (44 ) (19 ) (18 ) (1 ) (1 ) Amortization: Prior service costs 3 3 — — — Net (gain)/loss 13 1 8 — — Net periodic postretirement benefit cost $ 48 $ 4 $ 21 $ 2 $ 3

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Change in Unrecognized Tax Benefits	Changes during 2016 for unrecognized tax benefits were as follows: Mississippi Power Southern Power Southern Company (in millions) Unrecognized tax benefits as of December 31, 2015 $ 421 $ 8 $ 433 Tax positions from current periods — 12 12 Tax positions from prior periods 18 (1 ) 13 Balance as of September 30, 2016 $ 439 $ 19 $ 458
Impact on Effective Tax Rate, If Recognized	The impact on the effective tax rate, if recognized, is as follows: As of September 30, 2016 As of December 31, 2015 Mississippi Power Southern Power Southern Company Southern Company (in millions) Tax positions impacting the effective tax rate $ 1 $ 19 $ 20 $ 10 Tax positions not impacting the effective tax rate 438 — 438 423 Balance of unrecognized tax benefits $ 439 $ 19 $ 458 $ 433

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of energy-related derivatives	At September 30, 2016 , the net volume of energy-related derivative contracts for natural gas positions for the Southern Company system, together with the longest hedge date over which the respective entity is hedging its exposure to the variability in future cash flows for forecasted transactions and the longest non-hedge date for derivatives not designated as hedges, were as follows: Net Purchased mmBtu Longest Hedge Date Longest Non-Hedge Date (in millions) Southern Company (*) 540 2020 2022 Alabama Power 75 2020 — Georgia Power 148 2020 — Gulf Power 57 2020 — Mississippi Power 37 2020 — Southern Power 9 2017 2016 (*) Southern Company Gas' derivative instruments are comprised of both long and short natural gas positions. A long position is a contract to purchase natural gas and a short position is a contract to sell natural gas. Southern Company Gas' volume represents the net of long natural gas positions of 3.2 billion mmBtu and short natural gas positions of 2.9 billion mmBtu as of September 30, 2016.
Schedule of interest rate derivatives	At September 30, 2016 , the following interest rate derivatives were outstanding: Notional Amount Interest Rate Received Weighted Average Interest Rate Paid Hedge Maturity Date Fair Value (in millions) (in millions) Cash Flow Hedges of Forecasted Debt Gulf Power $ 80 3-month 2.32% December 2026 $ (6 ) Cash Flow Hedges of Existing Debt Mississippi Power 900 1-month 0.79% March 2018 (1 ) Fair Value Hedges of Existing Debt Southern Company (a) 250 1.30% 3-month August 2017 1 Southern Company (a) 300 2.75% 3-month June 2020 9 Georgia Power 250 5.40% 3-month June 2018 2 Georgia Power 200 4.25% 3-month December 2019 5 Georgia Power 500 1.95% 3-month December 2018 2 Derivatives not Designated as Hedges Southern Power 65 (b)(e) 3-month 2.50% October 2016 (f) — Southern Power 47 (c)(e) 3-month 2.21% October 2016 (f) — Southern Power 65 (d)(e) 3-month 2.21% November 2016 (g) — Southern Company Consolidated $ 2,657 $ 12 (a) Represents the Southern Company parent entity. (b) Swaption at RE Tranquillity LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (c) Swaption at RE Roserock LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. Subsequent to September 30, 2016, Roserock extended the maturity date of its swaption to December 31, 2016. (d) Swaption at RE Garland Holdings LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (e) Amortizing notional amount. (f) Represents the mandatory settlement date. Settlement will be based on a 15 -year amortizing swap. (g) Represents the mandatory settlement date. Settlement will be based on a 12 -year amortizing swap.
Schedule of foreign currency derivatives	At September 30, 2016 , the following foreign currency derivatives were outstanding: Pay Notional Pay Rate Receive Notional Receive Rate Hedge Fair Value (in millions) (in millions) (in millions) Cash Flow Hedges of Existing Debt Southern Power $ 677 2.95% € 600 1.00% June 2022 $ (2 ) Southern Power 564 3.78% 500 1.85% June 2026 1 Total $ 1,241 € 1,100 $ (1 )
Fair value of energy-related derivatives and interest rate derivatives	At September 30, 2016 , the fair value of energy-related derivatives, interest rate derivatives, and foreign currency derivatives was reflected in the balance sheets as follows: As of September 30, 2016 Derivative Category and Balance Sheet Location Assets Liabilities (in millions) Southern Company Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ 20 $ (62 ) Other deferred charges and assets/Other deferred credits and liabilities 13 (53 ) Total derivatives designated as hedging instruments for regulatory purposes $ 33 $ (115 ) Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ 4 $ (6 ) Other deferred charges and assets/Other deferred credits and liabilities — (1 ) As of September 30, 2016 Derivative Category and Balance Sheet Location Assets Liabilities (in millions) Interest rate derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ 8 $ (7 ) Other deferred charges and assets/Other deferred credits and liabilities 11 — Foreign currency derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ — $ (24 ) Other deferred charges and assets/Other deferred credits and liabilities 23 — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 46 $ (38 ) Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets/Liabilities from risk management activities, net of collateral $ 305 $ (345 ) Other deferred charges and assets/Other deferred credits and liabilities 58 (74 ) Total derivatives not designated as hedging instruments $ 363 $ (419 ) Gross amounts of recognized assets and liabilities $ 442 $ (572 ) Gross amounts offset in the Balance Sheet (*) $ (283 ) $ 394 Net amounts of assets and liabilities presented in the Balance Sheet $ 159 $ (178 ) Alabama Power Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Liabilities from risk management activities $ 4 $ (14 ) Other deferred charges and assets/Other deferred credits and liabilities 4 (7 ) Total derivatives designated as hedging instruments for regulatory purposes $ 8 $ (21 ) Gross amounts of recognized assets and liabilities $ 8 $ (21 ) Gross amounts offset in the Balance Sheet (*) $ (7 ) $ 7 Net amounts of assets and liabilities presented in the Balance Sheet $ 1 $ (14 ) Georgia Power Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Other current liabilities $ 7 $ (5 ) Other deferred charges and assets/Other deferred credits and liabilities 8 (11 ) Total derivatives designated as hedging instruments for regulatory purposes $ 15 $ (16 ) Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets/Other current liabilities $ 5 $ — Other deferred charges and assets/Other deferred credits and liabilities 5 — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 10 $ — Gross amounts of recognized assets and liabilities $ 25 $ (16 ) Gross amounts offset in the Balance Sheet (*) $ (11 ) $ 11 Net amounts of assets and liabilities presented in the Balance Sheet $ 14 $ (5 ) As of September 30, 2016 Derivative Category and Balance Sheet Location Assets Liabilities (in millions) Gulf Power Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Liabilities from risk management activities $ 1 $ (24 ) Other deferred charges and assets/Other deferred credits and liabilities — (27 ) Total derivatives designated as hedging instruments for regulatory purposes $ 1 $ (51 ) Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets/Liabilities from risk management activities $ — $ (6 ) Gross amounts of recognized assets and liabilities $ 1 $ (57 ) Gross amounts offset in the Balance Sheet (*) $ (1 ) $ 1 Net amounts of assets and liabilities presented in the Balance Sheet $ — $ (56 ) Mississippi Power Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets/Other current liabilities $ — $ (13 ) Other deferred charges and assets/Other deferred credits and liabilities 1 (8 ) Total derivatives designated as hedging instruments for regulatory purposes $ 1 $ (21 ) Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets/Other current liabilities $ — $ (1 ) Gross amounts of recognized assets and liabilities $ 1 $ (22 ) Gross amounts offset in the Balance Sheet (*) $ (1 ) $ 1 Net amounts of assets and liabilities presented in the Balance Sheet $ — $ (21 ) Southern Power Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets/Other current liabilities $ 2 $ (3 ) Other deferred charges and assets/Other deferred credits and liabilities — — Foreign currency derivatives: Other current assets/Other current liabilities $ — $ (24 ) Other deferred charges and assets/Other deferred credits and liabilities 23 — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 25 $ (27 ) Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets/Other current liabilities $ 1 $ — Gross amounts of recognized assets and liabilities $ 26 $ (27 ) Gross amounts offset in the Balance Sheet (*) $ (1 ) $ 1 Net amounts of assets and liabilities presented in the Balance Sheet $ 25 $ (26 ) (*) Includes any cash/financial collateral pledged or received. At December 31, 2015, the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at December 31, 2015 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets $ 3 $ 1 $ 2 $ — $ — Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets $ 3 $ — $ — $ — $ 3 Interest rate derivatives: Other current assets 19 — 5 1 — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 22 $ — $ 5 $ 1 $ 3 Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets $ 1 $ — $ — $ — $ 1 Interest rate derivatives: Other current assets 3 — — — 3 Total derivatives not designated as hedging instruments $ 4 $ — $ — $ — $ 4 Total asset derivatives $ 29 $ 1 $ 7 $ 1 $ 7 Liability Derivatives at December 31, 2015 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Liabilities from risk management activities (*) $ 130 $ 40 $ 12 $ 49 $ 29 Other deferred credits and liabilities 87 15 3 51 18 Total derivatives designated as hedging instruments for regulatory purposes $ 217 $ 55 $ 15 $ 100 $ 47 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Liabilities from risk management activities (*) $ 2 $ — $ — $ — $ — $ 2 Interest rate derivatives: Liabilities from risk management activities 23 15 — — — — Other deferred credits and liabilities 7 — 6 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 32 $ 15 $ 6 $ — $ — $ 2 Derivatives not designated as hedging instruments Energy-related derivatives: Liabilities from risk management activities (*) $ 1 $ — $ — $ — $ — $ 1 Total liability derivatives $ 250 $ 70 $ 21 $ 100 $ 47 $ 3 (*) Georgia Power, Mississippi Power, and Southern Power include current liabilities related to derivatives in other current liabilities.
Offsetting disclosure tables	Amounts related to energy-related derivative contracts and interest rate derivative contracts at December 31, 2015 are presented in the following table: Derivative Contracts at December 31, 2015 Fair Value Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Assets Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 7 $ 1 $ 2 $ — $ — $ 4 Gross amounts not offset in the Balance Sheet (b) (6 ) (1 ) (2 ) — — (1 ) Net energy-related derivative assets $ 1 $ — $ — $ — $ — $ 3 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 22 $ — $ 5 $ 1 $ — $ 3 Gross amounts not offset in the Balance Sheet (b) (9 ) — (4 ) — — — Net interest rate derivative assets $ 13 $ — $ 1 $ 1 $ — $ 3 Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 220 $ 55 $ 15 $ 100 $ 47 $ 3 Gross amounts not offset in the Balance Sheet (b) (6 ) (1 ) (2 ) — — (1 ) Net energy-related derivative liabilities $ 214 $ 54 $ 13 $ 100 $ 47 $ 2 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 30 $ 15 $ 6 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (9 ) — (4 ) — — — Net interest rate derivative liabilities $ 21 $ 15 $ 2 $ — $ — $ — (a) As of December 31, 2015, none of the registrants offset fair value amounts for multiple derivative instruments executed with the same counterparty in the balance sheets; therefore, gross and net amounts of derivative assets and liabilities presented in the balance sheets are the same. (b) Includes gross amounts subject to netting terms that are not offset in the balance sheets and any cash/financial collateral pledged or received.
Pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments	At September 30, 2016 and December 31, 2015, the pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments designated as regulatory hedging instruments and deferred were as follows: Regulatory Hedge Unrealized Gain (Loss) Recognized in the Balance Sheet at September 30, 2016 Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Energy-related derivatives: Other regulatory assets, current $ (52 ) $ (10 ) $ (2 ) $ (24 ) $ (13 ) Other regulatory assets, deferred (42 ) (4 ) (4 ) (26 ) (8 ) Other regulatory liabilities, current (a) 8 1 4 — — Other regulatory liabilities, deferred (b) 1 — 1 — — Total energy-related derivative gains (losses) $ (85 ) $ (13 ) $ (1 ) $ (50 ) $ (21 ) (a) Georgia Power includes other regulatory liabilities, current in other current liabilities. (b) Georgia Power includes other regulatory liabilities, deferred in other deferred credits and liabilities. Regulatory Hedge Unrealized Gain (Loss) Recognized in the Balance Sheet at December 31, 2015 Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Energy-related derivatives: Other regulatory assets, current $ (130 ) $ (40 ) $ (12 ) $ (49 ) $ (29 ) Other regulatory assets, deferred (87 ) (15 ) (3 ) (51 ) (18 ) Other regulatory liabilities, current (*) 3 1 2 — — Total energy-related derivative gains (losses) $ (214 ) $ (54 ) $ (13 ) $ (100 ) $ (47 ) (*) Georgia Power includes other regulatory liabilities, current in other current liabilities.
Pre-tax effects of interest rate derivatives, designated as cash flow hedging instruments	For the three months ended September 30, 2016 and 2015 , the pre-tax effects of energy-related derivatives, interest rate derivatives, and foreign currency derivatives designated as cash flow hedging instruments were as follows: Derivatives in Cash Flow Hedging Relationships Gain (Loss) Recognized in OCI on Derivative (Effective Portion) Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) Statements of Income Location Amount 2016 2015 2016 2015 (in millions) (in millions) Southern Company Energy-related derivatives $ — $ — Amortization $ 1 $ — Interest rate derivatives (6 ) (28 ) Interest expense, net of amounts capitalized (6 ) (2 ) Foreign currency derivatives 37 — Interest expense, net of amounts capitalized (6 ) — Other income (expense), net (*) 7 — Total $ 31 $ (28 ) $ (4 ) $ (2 ) Alabama Power Interest rate derivatives $ — $ (10 ) Interest expense, net of amounts capitalized $ (2 ) $ (1 ) Georgia Power Interest rate derivatives $ — $ (18 ) Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Southern Power Energy-related derivatives $ — $ — Amortization $ 1 $ — Foreign currency derivatives 37 — Interest expense, net of amounts capitalized (6 ) — Other income (expense), net (*) 7 — Total $ 37 $ — $ 2 $ — (*) The reclassification from accumulated OCI into other income (expense), net completely offsets currency gains and losses arising from changes in the U.S. currency exchange rates used to record the euro-denominated notes. For the nine months ended September 30, 2016 and 2015 , the pre-tax effects of energy-related derivatives, interest rate derivatives, and foreign currency derivatives designated as cash flow hedging instruments recognized in OCI and those reclassified from accumulated OCI into earnings were as follows: Derivatives in Cash Flow Gain (Loss) Gain (Loss) Reclassified from Accumulated OCI into Statements of Income Location Amount 2016 2015 2016 2015 (in millions) (in millions) Southern Company Energy-related derivatives $ (1 ) $ — Amortization $ 1 $ — Interest rate derivatives (189 ) (26 ) Interest expense, net of amounts capitalized (13 ) (7 ) Foreign currency derivatives (1 ) — Interest expense, net of amounts capitalized (7 ) — Other income (expense), net (*) (13 ) — Total $ (191 ) $ (26 ) $ (32 ) $ (7 ) Alabama Power Interest rate derivatives $ (3 ) $ (9 ) Interest expense, net of amounts capitalized $ (5 ) $ (2 ) Georgia Power Interest rate derivatives $ — $ (17 ) Interest expense, net of amounts capitalized $ (3 ) $ (3 ) Gulf Power Interest rate derivatives $ (7 ) $ — Interest expense, net of amounts capitalized $ — $ — Mississippi Power Interest rate derivatives $ (1 ) $ — Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Southern Power Energy-related derivatives $ (1 ) $ — Amortization $ 1 $ — Interest rate derivatives — — Interest expense, net of amounts capitalized (1 ) (1 ) Foreign currency derivatives (1 ) — Interest expense, net of amounts capitalized (7 ) — Other income (expense), net (*) (13 ) — Total $ (2 ) $ — $ (20 ) $ (1 ) (*) The reclassification from accumulated OCI into other income (expense), net completely offsets currency gains and losses arising from changes in the U.S. currency exchange rates used to record the euro-denominated notes.
Pre-tax effects of interest rate derivatives, designated as fair value hedging instruments	For the three and nine months ended September 30, 2016 and 2015 , the pre-tax effects of interest rate derivatives designated as fair value hedging instruments were as follows: Derivatives in Fair Value Hedging Relationships Gain (Loss) Three Months Ended September 30, Nine Months Ended September 30, Derivative Category Statements of Income Location 2016 2015 2016 2015 (in millions) (in millions) Southern Company Interest rate derivatives: Interest expense, net of amounts capitalized $ (9 ) $ 15 $ 15 $ 19 Georgia Power Interest rate derivatives: Interest expense, net of amounts capitalized $ (5 ) $ 7 $ 10 $ 9

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Schedule of Business Acquisitions	The allocation of the purchase price is as follows: PowerSecure Purchase Price September 30, 2016 (in millions) Current assets $ 172 Property, plant, and equipment 46 Goodwill 284 Intangible assets 101 Other assets 6 Current liabilities (145 ) Long-term debt, including current portion (18 ) Deferred credits and other liabilities (17 ) Total purchase price $ 429 The following table presents the preliminary purchase price allocation: Southern Company Gas Purchase Price September 30, 2016 (in millions) Current assets $ 1,557 Property, plant, and equipment 10,108 Goodwill 5,937 Intangible assets 400 Regulatory assets 1,118 Other assets 229 Current liabilities (2,201 ) Other liabilities (4,712 ) Long-term debt (4,261 ) Noncontrolling interests (174 ) Total purchase price $ 8,001 During 2016 , in accordance with its overall growth strategy, Southern Power or one of its wholly-owned subsidiaries, Southern Renewable Partnerships, LLC and Southern Renewable Energy, Inc., acquired or contracted to acquire the projects discussed below. Acquisition-related costs were expensed as incurred and were not material. The acquisitions do not include any contingent consideration unless specifically noted. Project Facility Resource Seller; Acquisition Date Approximate Nameplate Capacity ( MW ) Location Southern Power Percentage Ownership Actual/Expected COD PPA Counterparties for Plant Output PPA Contract Period Acquisitions for the Nine Months Ended September 30, 2016 Calipatria Solar Solar Frontier Americas Holding LLC 20 Imperial County, CA 90 % February 2016 San Diego Gas & Electric Company 20 years East Pecos Solar First Solar, Inc. 120 Pecos County, TX 100 % December 2016 Austin Energy 15 years Grant Plains Wind Apex Clean Energy Holdings, LLC 147 Grant County, OK 100 % December 2016 Oklahoma Municipal Power Authority and Steelcase Inc. 20 years and 12 years (a) Grant Wind Wind Apex Clean Energy Holdings, LLC 151 Grant County, OK 100 % April 2016 Western Farmers, East Texas, and Northeast Texas Electric Cooperative 20 years Henrietta Solar SunPower Corp. 102 Kings County, CA 51 % (b) July 2016 Pacific Gas and Electric Company 20 years Lamesa Solar RES America Developments Inc. 102 Dawson County, TX 100 % First quarter 2017 City of Garland, Texas 15 years Passadumkeag Wind Quantum Utility Generation, LLC 42 Penobscot County, ME 100 % July 2016 Western Massachusetts Electric Company 15 years Rutherford Solar Cypress Creek Renewables, LLC 74 Rutherford County, NC 90 % December 2016 Duke Energy Carolinas, LLC 15 years Acquisitions Subsequent to September 30, 2016 Mankato Natural Gas Calpine Corporation October 26, 2016 375 (c) Mankato, MN 100 % N/A (c) Northern States Power Company 10 years Wake Wind Wind Invenergy Wind Global LLC October 26, 2016 257 Floyd and Crosby Counties, TX 90.1 % October 2016 Equinix Enterprises, Inc. and Owens Corning 12 years (a) In addition to the 20 -year and 12 -year PPAs, the facility has a 10 -year contract with Allianz Risk Transfer (Bermuda) Ltd. (b) Southern Power owns 100% of the class A membership interests and a wholly-owned subsidiary of the seller owns 100% of the class B membership interests. Southern Power and the class B member are entitled to 51% and 49% , respectively, of all cash distributions from the project. In addition, Southern Power is entitled to substantially all of the federal tax benefits with respect to the transaction. (c) The Mankato facility is a fully operational 375 -MW natural gas-fired combined-cycle facility with an additional 345 -MW expansion under development.
Schedule of Construction Projects	During the nine months ended September 30, 2016 , in accordance with its overall growth strategy, Southern Power completed construction of and placed in service, or continued construction of, the projects set forth in the following table. Through September 30, 2016 , total costs of construction incurred for the following projects were $3.0 billion , of which $1.2 billion remains in CWIP. Including the total construction costs incurred through September 30, 2016 and the acquisition prices allocated to CWIP, total aggregate construction costs for the following projects are estimated to be $3.1 billion to $3.2 billion . The ultimate outcome of these matters cannot be determined at this time. Solar Facility Seller Approximate Nameplate Capacity ( MW ) Location Actual/Expected COD PPA Counterparties for Plant Output PPA Contract Period Projects Completed During the Nine Months Ended September 30, 2016 Butler Solar Farm Strata Solar Development, LLC 22 Taylor County, GA February 2016 Georgia Power (a) 20 years Desert Stateline (b) First Solar Development, LLC 299 (c) San Bernardino County, CA Through July 2016 Southern California Edison Company (SCE) 20 years Garland A Recurrent Energy, LLC 20 Kern County, CA August 2016 SCE 20 years Pawpaw Longview Solar, LLC 30 Taylor County, GA March 2016 Georgia Power (a) 30 years Tranquillity Recurrent Energy, LLC 205 Fresno County, CA July 2016 Shell Energy North America (US), LP/SCE 18 years Projects Under Construction as of September 30, 2016 Butler CERSM, LLC and Community Energy, Inc. 103 Taylor County, GA December 2016 Georgia Power (a) 30 years Garland Recurrent Energy, LLC 185 Kern County, CA October 2016 SCE 15 years Roserock Recurrent Energy, LLC 160 Pecos County, TX November 2016 Austin Energy 20 years Sandhills N/A 146 Taylor County, GA October 2016 Cobb, Flint, Irwin, Middle Georgia and Sawnee Electric Membership Corporations 25 years (a) Affiliate PPA approved by the FERC. (b) On March 29, 2016, Southern Power acquired an additional 15% interest in Desert Stateline. As a result, Southern Power and the class B member are entitled to 66% and 34% , respectively, of all cash distributions from Desert Stateline. In addition, Southern Power will continue to be entitled to substantially all of the federal tax benefits with respect to the transaction. (c) The facility has a total of 299 MWs, of which 110 MWs were placed in service in the fourth quarter 2015 and 189 MWs were placed in service during the nine months ended September 30, 2016 .
Business Acquisition, Pro Forma Information	The following summarized unaudited pro forma consolidated statement of earnings information assumes that the acquisition of Southern Company Gas was completed on January 1, 2015. The summarized unaudited pro forma consolidated statement of earnings information includes adjustments for (i) intercompany sales, (ii) amortization of intangible assets, (iii) adjustments to interest expense to reflect current interest rates on Southern Company Gas debt and additional interest expense associated with borrowings by Southern Company to fund the Merger, and (iv) the elimination of nonrecurring expenses associated with the Merger. For the Nine Months Ended September 30, 2016 2015 Operating revenues (in millions) $ 16,609 $ 16,865 Net income attributable to Southern Company (in millions) $ 2,369 $ 2,269 Basic EPS $ 2.50 $ 2.43 Diluted EPS $ 2.48 $ 2.42

Segment and Related Informati29

Segment and Related Information (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Financial data for business segments	Financial data for business segments and products and services for the three and nine months ended September 30, 2016 and 2015 was as follows: Electric Utilities Traditional Electric Operating Companies Southern Power Eliminations Total Southern Company Gas All Other Eliminations Consolidated (in millions) Three Months Ended Operating revenues $ 5,236 $ 500 $ (117 ) $ 5,619 $ 543 $ 139 $ (37 ) $ 6,264 Segment net income (loss) (a)(b) 1,018 176 — 1,194 4 (67 ) (1 ) 1,130 Nine Months Ended Operating revenues $ 13,120 $ 1,189 $ (330 ) $ 13,979 $ 543 $ 311 $ (118 ) $ 14,715 Segment net income (loss) (a)(c) 2,076 315 — 2,391 4 (161 ) (8 ) 2,226 Total assets at September 30, 2016 $ 71,448 $ 12,351 $ (440 ) $ 83,359 $ 21,185 $ 2,974 $ (1,156 ) $ 106,362 Three Months Ended Operating revenues $ 5,098 $ 401 $ (109 ) $ 5,390 $ — $ 37 $ (26 ) $ 5,401 Segment net income (loss) (a)(b) 874 102 — 976 — (18 ) 1 959 Nine Months Ended Operating revenues $ 13,123 $ 1,086 $ (322 ) $ 13,887 $ — $ 120 $ (86 ) $ 13,921 Segment net income (loss) (a)(c) 1,912 181 — 2,093 — 3 — 2,096 Total assets at December 31, 2015 $ 69,052 $ 8,905 $ (397 ) $ 77,560 $ — $ 1,819 $ (1,061 ) $ 78,318 (a) Attributable to Southern Company. (b) Segment net income (loss) for the traditional electric operating companies includes pre-tax charges for estimated probable losses on the Kemper IGCC of $88 million ( $54 million after tax) and $150 million ( $93 million after tax) for the three months ended September 30, 2016 and 2015 , respectively. See Note (B) under " Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate " for additional information. (c) Segment net income (loss) for the traditional electric operating companies includes pre-tax charges for estimated probable losses on the Kemper IGCC of $222 million ( $137 million after tax) and $182 million ( $112 million after tax) for the nine months ended September 30, 2016 and 2015 , respectively. See Note (B) under " Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate " for additional information.
Financial data for products and services	Products and Services Electric Utilities' Revenues Period Retail Wholesale Other Total (in millions) Three Months Ended September 30, 2016 $ 4,808 $ 613 $ 198 $ 5,619 Three Months Ended September 30, 2015 4,701 520 169 5,390 Nine Months Ended September 30, 2016 $ 11,932 $ 1,455 $ 592 $ 13,979 Nine Months Ended September 30, 2015 11,958 1,435 494 13,887 Southern Company Gas' Revenues Period Gas Gas All Other Total (in millions) Three and Nine Months Ended September 30, 2016 $ 420 $ 126 $ (3 ) $ 543

Introduction - Asset Retirement

Introduction - Asset Retirement Obligations (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	$ 3,759
Liabilities incurred	41
Liabilities settled	(117)
Accretion	119
Cash flow revisions	712
Balance at end of period	4,514
Alabama Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	1,448
Liabilities incurred	5
Liabilities settled	(12)
Accretion	55
Cash flow revisions	31
Balance at end of period	1,527
Georgia Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	1,916
Liabilities incurred	0
Liabilities settled	(93)
Accretion	56
Cash flow revisions	675
Balance at end of period	2,554
Gulf Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	130
Liabilities incurred	0
Liabilities settled	0
Accretion	2
Cash flow revisions	2
Balance at end of period	134
Mississippi Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	177
Liabilities incurred	15
Liabilities settled	(12)
Accretion	3
Cash flow revisions	7
Balance at end of period	190
Southern Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	21
Liabilities incurred	18
Liabilities settled	0
Accretion	1
Cash flow revisions	0
Balance at end of period	$ 40

Introduction - Goodwill and Int

Introduction - Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill	$ 6,223	$ 2
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - gross carrying amount	906
Other intangibles subject to amortization - accumulated amortization	(39)	(12)
Other intangibles subject to amortization - net	867
Total other intangible assets - gross	981
Total other intangible assets - net	942	317
Southern Company [Member]
Goodwill [Line Items]
Goodwill	6,223
Southern Power [Member]
Goodwill [Line Items]
Goodwill	2	2
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - accumulated amortization	(16)	(12)
Total other intangible assets - net	$ 389	$ 317
Customer relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	11 years
Customer relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	26 years
Customer relationships [Member] | Southern Company [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - gross carrying amount	$ 268
Other intangibles subject to amortization - accumulated amortization	(16)
Other intangibles subject to amortization - net	$ 252
Trade names [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	5 years
Trade names [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	28 years
Trade names [Member] | Southern Company [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - gross carrying amount	$ 158
Other intangibles subject to amortization - accumulated amortization	(3)
Other intangibles subject to amortization - net	$ 155
Patents [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	3 years
Patents [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	10 years
Patents [Member] | Southern Company [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - gross carrying amount	$ 4
Other intangibles subject to amortization - accumulated amortization	0
Other intangibles subject to amortization - net	$ 4
Backlog [Member] | Southern Company [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	5 years
Other intangibles subject to amortization - gross carrying amount	$ 5
Other intangibles subject to amortization - accumulated amortization	0
Other intangibles subject to amortization - net	$ 5
Storage and transportation contracts [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	1 year
Storage and transportation contracts [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	5 years
Storage and transportation contracts [Member] | Southern Company [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - gross carrying amount	$ 64
Other intangibles subject to amortization - accumulated amortization	(4)
Other intangibles subject to amortization - net	$ 60
Software and other [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	1 year
Software and other [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	12 years
Software and other [Member] | Southern Company [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - gross carrying amount	$ 2
Other intangibles subject to amortization - accumulated amortization	0
Other intangibles subject to amortization - net	$ 2
PPA fair value adjustments [Member] | Southern Company [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	19 years
PPA fair value adjustments [Member] | Southern Company [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	20 years
PPA fair value adjustments [Member] | Southern Power [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - gross carrying amount	$ 405
Other intangibles subject to amortization - accumulated amortization	(16)
Other intangibles subject to amortization - net	$ 389
PPA fair value adjustments [Member] | Southern Power [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	19 years
PPA fair value adjustments [Member] | Southern Power [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangibles subject to amortization - estimated useful life	20 years
FCC Licenses [Member] | Southern Company [Member]
Indefinite-lived Intangible Assets [Line Items]
Other intangible assets not subject to amortization	$ 75

Introduction - Intangibles, Amo

Introduction - Intangibles, Amortization (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 25	$ 27
Southern Power [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 2	$ 4

Introduction - Narrative (Detai

Introduction - Narrative (Details) $ in Millions	1 Months Ended	9 Months Ended	33 Months Ended
	Sep. 30, 2016USD ($)location	Sep. 30, 2016USD ($)location	Sep. 30, 2016USD ($)agreementlocation	Jul. 10, 2016	Dec. 31, 2015USD ($)
Related Party Transaction [Line Items]
Construction work in progress	$ 10,069	$ 10,069	$ 10,069		$ 9,082
Other intangible assets, net of amortization	$ 942	$ 942	$ 942		317
Georgia Power [Member]
Related Party Transaction [Line Items]
Number of military bases for renewable generation | location	2	2	2
Construction work in progress	$ 4,888	$ 4,888	$ 4,888		4,775
Due to related parties current	451	$ 451	451		411
ARO period of update cycle		3 years
Alabama Power [Member]
Related Party Transaction [Line Items]
Construction work in progress	473	$ 473	473		801
Due to related parties current	309	309	309		278
Southern Power [Member]
Related Party Transaction [Line Items]
Construction work in progress	1,652	1,652	1,652		1,137
Due to related parties current	91	91	91		66
Other intangible assets, net of amortization	389	389	$ 389		$ 317
Affiliated Entity [Member] | Georgia Power [Member]
Related Party Transaction [Line Items]
Number of agreements for renewable generation | agreement			2
PowerSecure International, Inc. [Member] | Georgia Power [Member]
Related Party Transaction [Line Items]
Construction work in progress	108	108	$ 108
Due to related parties current	0.2	$ 0.2	$ 0.2
Southern Natural Gas Company, LLC [Member] | Georgia Power [Member]
Related Party Transaction [Line Items]
Related party transactions	8
Southern Natural Gas Company, LLC [Member] | Southern Company [Member]
Related Party Transaction [Line Items]
Related party transactions	16
Southern Natural Gas Company, LLC [Member] | Alabama Power [Member]
Related Party Transaction [Line Items]
Related party transactions	1
Southern Natural Gas Company, LLC [Member] | Southern Power [Member]
Related Party Transaction [Line Items]
Related party transactions	$ 2
Southern Natural Gas Company, LLC [Member]
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage by parent				50.00%

Contingencies and Regulatory 34

Contingencies and Regulatory Matters - Recovery Balance of Each Regulatory Clause - Alabama Power (Details) - Alabama Power [Member] - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Under recovered regulatory clause revenues [Member]
Loss Contingencies [Line Items]
Rate CNP Compliance	$ 0	$ 43
Rate CNP PPA	52	99
Deferred under recovered regulatory clause revenues [Member]
Loss Contingencies [Line Items]
Rate CNP Compliance	23	0
Rate CNP PPA	87	0
Other regulatory liabilities, current [Member]
Loss Contingencies [Line Items]
Retail Energy Cost Recovery	0	238
Deferred over recovered regulatory clause revenues [Member]
Loss Contingencies [Line Items]
Retail Energy Cost Recovery	134	0
Other regulatory liabilities, deferred [Member]
Loss Contingencies [Line Items]
Natural Disaster Reserve	$ 71	$ 75

Contingencies and Regulatory 35

Contingencies and Regulatory Matters - Recovery Balance of Each Regulatory Clause - Gulf Power (Details) - Gulf Power [Member] - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Other regulatory liabilities, current [Member]
Loss Contingencies [Line Items]
Fuel Cost Recovery	$ 20	$ 18
Purchased Power Capacity Recovery - Over	3	0
Environmental Cost Recovery	5	0
Energy Conservation Cost Recovery	0	4
Under recovered regulatory clause revenues [Member]
Loss Contingencies [Line Items]
Purchased Power Capacity Recovery - Under	0	1
Environmental Cost Recovery	0	19
Energy Conservation Costs - Under	$ 2	$ 0

Contingencies and Regulatory 36

Contingencies and Regulatory Matters - Current And Actual Cost Estimate (Details) - Mississippi Power [Member] - USD ($) $ in Millions	Apr. 08, 2016	Sep. 30, 2016	Dec. 31, 2012	Dec. 03, 2015
Loss Contingencies [Line Items]
Additional DOE Grants			$ 245
Kemper IGCC [Member]
Loss Contingencies [Line Items]
Plant Subject to Cost Cap		$ 5,300	2,880
Lignite Mine and Equipment		230
CO2 Pipeline Facilities		110
AFUDC		710
Combined Cycle and Related Assets Placed in Service – Incremental		30
General Exceptions		90
Deferred Costs		200
Additional DOE Grants		(140)
Total Kemper IGCC, Actual Costs		$ 6,530
Purchase of Interest		100.00%		15.00%
Government grants received	$ 137
Project Estimate [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Plant Subject to Cost Cap		$ 2,400
Lignite Mine and Equipment		210
CO2 Pipeline Facilities		140
AFUDC		170
Combined Cycle and Related Assets Placed in Service – Incremental		0
General Exceptions		50
Deferred Costs		0
Additional DOE Grants		0
Total Kemper IGCC, Actual Costs		2,970
Current Estimate [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Plant Subject to Cost Cap		5,520
Lignite Mine and Equipment		230
CO2 Pipeline Facilities		110
AFUDC		750
Combined Cycle and Related Assets Placed in Service – Incremental		40
General Exceptions		100
Deferred Costs		210
Additional DOE Grants		(140)
Total Kemper IGCC, Actual Costs		$ 6,820
Maximum [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Plant Subject to Cost Cap			$ 2,880

Contingencies and Regulatory 37

Contingencies and Regulatory Matters - Narrative (Details)	Oct. 20, 2016USD ($)	Oct. 12, 2016USD ($)	Sep. 30, 2016USD ($)statemi	Aug. 17, 2016USD ($)	Jun. 09, 2016USD ($)	Jun. 03, 2016	May 03, 2016USD ($)	May 01, 2016USD ($)	Mar. 31, 2016USD ($)MW	Dec. 31, 2015USD ($)	Dec. 05, 2015USD ($)	Dec. 03, 2015	Jul. 07, 2015USD ($)	Apr. 15, 2015USD ($)	Jan. 01, 2014USD ($)	Mar. 19, 2013	Jun. 30, 2019USD ($)	Apr. 30, 2016MW	Mar. 31, 2016USD ($)MW	Sep. 30, 2015USD ($)	Feb. 28, 2013USD ($)	Jan. 31, 2013USD ($)	Sep. 30, 2016USD ($)statemi	Sep. 30, 2015USD ($)	Jun. 30, 2016USD ($)	Sep. 30, 2016USD ($)clausestatemiMW	Sep. 30, 2015USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2010	Dec. 31, 2009USD ($)	Dec. 31, 2008USD ($)	Sep. 30, 2016USD ($)statemi	Sep. 30, 2016USD ($)statemi	Dec. 31, 2020USD ($)	Dec. 31, 2022	Jan. 01, 2121	Aug. 31, 2016	Jul. 28, 2016MW	May 17, 2016USD ($)	Apr. 01, 2016USD ($)	Mar. 09, 2016USD ($)	Jan. 05, 2016USD ($)
Loss Contingencies [Line Items]
Maximum borrowing capacity			$ 8,445,000,000																				$ 8,445,000,000			$ 8,445,000,000											$ 8,445,000,000	$ 8,445,000,000
Construction work in progress			$ 10,069,000,000							$ 9,082,000,000													$ 10,069,000,000			$ 10,069,000,000				$ 9,082,000,000							$ 10,069,000,000	$ 10,069,000,000
Number of States in which Entity Operates | state			4																				4			4											4	4
Allowance for equity funds used during construction																							$ 52,000,000	$ 60,000,000		$ 150,000,000	$ 163,000,000
Other Regulatory Assets Current			$ 414,000,000							402,000,000													414,000,000			414,000,000				402,000,000							$ 414,000,000	$ 414,000,000
Scenario, Forecast [Member] | Customers [Member]
Loss Contingencies [Line Items]
Percentage basis net merger savings																																								60.00%
Kemper IGCC [Member]
Loss Contingencies [Line Items]
Pre-tax charge to income																							88,000,000	150,000,000		222,000,000	182,000,000
After tax charge to income																							54,000,000	93,000,000		137,000,000	112,000,000
Georgia Power [Member]
Loss Contingencies [Line Items]
Environmental remediation liability			23,000,000																				23,000,000			23,000,000											23,000,000	23,000,000
Capacity of renewable resources approved for procurement | MW																																											1,200
Capacity of renewable resources approved for self-build | MW																																											200
Rate ECR increase (decrease)																																												(15.00%)
Approved increase (decrease) in annual billings based on fuel cost recovery rate																																												$ (313,000,000)
Accrual under alternate rate plan																										30,000,000
Additional construction capital costs										3,300,000,000															$ 141,000,000
Percentage of proportionate share owed in consortium agreement																																				45.70%
Maximum borrowing capacity			1,750,000,000																				1,750,000,000			$ 1,750,000,000											1,750,000,000	1,750,000,000
Increase (decrease) in projected certified construction capital costs																										5.00%
Estimated in-service capital cost																																			$ 4,418,000,000
Amendment to estimated In-service capital cost																					$ 4,800,000,000
Retail rate of return on common equity																																10.95%
Construction work in progress			4,888,000,000							4,775,000,000													4,888,000,000			$ 4,888,000,000				4,775,000,000							4,888,000,000	4,888,000,000
Allowance for equity funds used during construction																										36,000,000	24,000,000
Other Regulatory Assets Current			115,000,000							123,000,000													115,000,000			115,000,000				123,000,000							115,000,000	115,000,000
Georgia Power [Member] | Other Current Liabilities [Member]
Loss Contingencies [Line Items]
Over recovered fuel balance			125,000,000																				125,000,000			125,000,000											125,000,000	125,000,000
Georgia Power [Member] | Other deferred credits and liabilities [Member]
Loss Contingencies [Line Items]
Over recovered fuel balance										116,000,000																				116,000,000
Georgia Power [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Capacity of renewable resources considered for renewable commercial and industrial program | MW																																											200
Storm restoration costs			155,000,000																				155,000,000			155,000,000											155,000,000	155,000,000
Additional construction capital costs																																				$ 114,000,000
Georgia Power [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Storm restoration costs			130,000,000																				130,000,000			130,000,000											130,000,000	130,000,000
Georgia Power [Member] | Intercession City Combustion Turbine [Member]
Loss Contingencies [Line Items]
Capacity of units approved for decertification | MW																																											143
Jointly owned utility plant, proportionate ownership share																																										33.00%
Georgia Power [Member] | Scenario, Forecast [Member]
Loss Contingencies [Line Items]
Additional construction capital costs																													$ 5,440,000,000
Amendment to estimated In-service capital cost																													5,680,000,000
Percent of basis points																																							0.95%		0.30%
Requested rate increase (decrease) amount																												$ 70,000,000											$ (325,000,000)
Requested rate increase (decrease) amount, reduction in net income																																							$ (115,000,000)
Georgia Power [Member] | Scenario, Forecast [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Cost recovery, new nuclear																	$ 99,000,000
Georgia Power [Member] | Plant Mitchell Units 3, 4A, and 4B [Member]
Loss Contingencies [Line Items]
Capacity of units approved for decertification | MW																																											217
Georgia Power [Member] | Plant Kraft Unit 1 [Member]
Loss Contingencies [Line Items]
Capacity of units approved for decertification | MW																																											17
Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member]
Loss Contingencies [Line Items]
Maximum borrowing capacity																																														$ 920,000,000
Estimated in-service capital cost														$ 5,000,000,000
Construction work in progress			3,800,000,000																				3,800,000,000			3,800,000,000											3,800,000,000	3,800,000,000
Construction financing costs			1,200,000,000
Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Project settlement cost to be capitalized										350,000,000																				350,000,000
Project settlement cost to be capitalized, amount paid to date			256,000,000																				256,000,000			$ 256,000,000											256,000,000	256,000,000
Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member] | Scenario, Forecast [Member]
Loss Contingencies [Line Items]
Construction financing costs																	22,000,000												2,400,000,000
Monthly Operational Readiness Costs																	$ 2,000,000
Georgia Power [Member] | Plant Vogtle Unit 3 [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Period Of Additional Current Schedule Pressure																										4 months
Georgia Power [Member] | Plant Vogtle Unit 3 [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Period Of Additional Current Schedule Pressure																										3 months
Gulf Power [Member]
Loss Contingencies [Line Items]
Environmental remediation liability			46,000,000																				46,000,000			$ 46,000,000											46,000,000	46,000,000
Regulatory assets									$ 63,000,000										$ 63,000,000
Maximum borrowing capacity			280,000,000																				280,000,000			$ 280,000,000											280,000,000	280,000,000
Public utilities, approved return on equity percentage																										10.25%
Construction work in progress			64,000,000							48,000,000													64,000,000			$ 64,000,000				48,000,000							64,000,000	64,000,000
Reduction in depreciation expense																										$ 0				20,100,000	$ 8,400,000	$ 62,500,000
Number of regulatory clauses | clause																										4
Other Regulatory Assets Current			62,000,000							90,000,000													62,000,000			$ 62,000,000				90,000,000							62,000,000	62,000,000
Gulf Power [Member] | Scenario, Forecast [Member]
Loss Contingencies [Line Items]
Approved increase (decrease) in fuel rates amount																												(41,000,000)
Gulf Power [Member] | Plant Scherer Unit 3 [Member] | Scenario, Forecast [Member]
Loss Contingencies [Line Items]
Approved increase (decrease) in fuel rates amount																												14,000,000	11,000,000
Gulf Power [Member] | Plant Smith Units 1 and 2 [Member]
Loss Contingencies [Line Items]
Capacity of units approved for decertification | MW									357										357
Southern Company Gas [Member]
Loss Contingencies [Line Items]
Environmental remediation liability			433,000,000																				433,000,000			433,000,000											433,000,000	433,000,000
Maximum borrowing capacity			2,000,000,000																				2,000,000,000			2,000,000,000											2,000,000,000	2,000,000,000
Infrastructure Improvement Program, Annual Investment Amount																										110,000,000
Infrastructure Improvement Program, Petitioned Annual Investment Amount																										44,000,000
Southern Company Gas [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Infrastructure Improvement Program, Annual Investment Amount																										250,000,000
Southern Company Gas [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Infrastructure Improvement Program, Annual Investment Amount																										10,000,000
Nicor Gas [Member]
Loss Contingencies [Line Items]
Loss contingency damages sought																				$ 300,000
Maximum borrowing capacity			700,000,000																				700,000,000			700,000,000											700,000,000	700,000,000
Mississippi Power [Member]
Loss Contingencies [Line Items]
Increase in base rate under cost based electric tariff due to settlement								$ 7,000,000
Over recovered fuel cost			58,000,000							71,000,000													58,000,000			58,000,000				71,000,000							58,000,000	58,000,000
Approved increase (decrease) in fuel rates amount				$ 18,000,000			$ (2,000,000)
Approved increase (decrease) in annual billings based on fuel cost recovery rate				$ (51,000,000)																																											$ (120,000,000)
Maximum borrowing capacity			175,000,000																				175,000,000			175,000,000											175,000,000	175,000,000
Construction work in progress			2,525,000,000							2,254,000,000													2,525,000,000			$ 2,525,000,000				2,254,000,000							2,525,000,000	2,525,000,000
Annual PEP filing rate increase amount																																													$ 5,000,000
Approved rate increase (decrease) percentage															3.00%	15.00%
Plant capacity under coal gasification combined cycle technology (in MWs) | MW																										582
Costs associated with CCP12 grant funds																																	$ 245,000,000
Settlement agreement collection amount to mitigate rate impact year two															$ 156,000,000
Allowance for equity funds used during construction																							31,000,000	29,000,000		$ 90,000,000	82,000,000
Retail rate recovery													$ 342,000,000
Carrying costs associated with retail rate recovery													$ 29,000,000
Other Regulatory Assets Current			118,000,000							95,000,000													118,000,000			118,000,000				95,000,000							118,000,000	118,000,000
Regulatory liabilities			7,000,000																				7,000,000			7,000,000											7,000,000	7,000,000
Mississippi Power [Member] | Construction in Progress [Member]
Loss Contingencies [Line Items]
Estimate of possible loss			2,630,000,000																				2,630,000,000			2,630,000,000											2,630,000,000	2,630,000,000
Mississippi Power [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Approved rate increase (decrease) percentage				2.00%
Costs due to extension of in-service date																										35,000,000
Mississippi Power [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Costs due to extension of in-service date																										25,000,000
Mississippi Power [Member] | MRA Revenue [Member]
Loss Contingencies [Line Items]
Over recovered fuel cost			17,000,000							24,000,000													17,000,000			17,000,000				24,000,000							17,000,000	17,000,000
Approved increase (decrease) in fuel rates amount																										(11,000,000)
Mississippi Power [Member] | MB Revenue [Member]
Loss Contingencies [Line Items]
Over recovered fuel cost			1,000,000							1,000,000													1,000,000			1,000,000				1,000,000							1,000,000	1,000,000
Approved increase (decrease) in fuel rates amount																										(1,000,000)
Mississippi Power [Member] | Scenario, Forecast [Member]
Loss Contingencies [Line Items]
AFUDC cost																													$ 11,000,000
Approved increase (decrease) in fuel rates amount																												$ 22,000,000
Mississippi Power [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Period of amortization of regulatory assets									36 months
Regulatory assets			$ 105,000,000																				$ 105,000,000			$ 105,000,000											$ 105,000,000	$ 105,000,000
Pipeline Infrastructure (in miles) | mi			61																				61			61											61	61
Estimated cost																										$ 5,300,000,000							2,880,000,000
Costs associated with CCP12 grant funds																										(140,000,000)
Pre-tax charge to income																							$ 88,000,000			222,000,000												$ 2,630,000,000
After tax charge to income																							$ 54,000,000			137,000,000												$ 1,630,000,000
Monthly charge of allowance for equity funds used during construction																										15,000,000
Monthly cost regulatory assets deferred																										$ 3,000,000
Allowance for equity funds used during construction																																					$ 352,000,000
Purchase of interest			100.00%									15.00%											100.00%			100.00%											100.00%	100.00%
Maximum cap construction cost																										$ 6,530,000,000
Period Of Commercial Operations Established By Discovery Docket																										5 years
Other Regulatory Assets Current			$ 105,000,000																				$ 105,000,000			$ 105,000,000											$ 105,000,000	$ 105,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Cost Estimate Extension [Member]
Loss Contingencies [Line Items]
Estimated cost																							$ 53,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Post In-Service Costs [Member]
Loss Contingencies [Line Items]
Estimated cost																										78,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Current Estimate [Member]
Loss Contingencies [Line Items]
Estimated cost																										5,520,000,000
Costs associated with CCP12 grant funds																										(140,000,000)
Maximum cap construction cost																										6,820,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | In-Service Asset Proposal [Member]
Loss Contingencies [Line Items]
Approved increase (decrease) in fuel rates amount											$ 126,000,000															$ 159,000,000
Public utilities, approved return on equity percentage												9.225%
Public utilities approved equity capital structure percentage												49.733%
Customer refund																			$ 11,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Denbury Onshore, Contractor [Member]
Loss Contingencies [Line Items]
Long-term contract for purchase of percentage of carbon dioxide captured from plant			70.00%			100.00%																	70.00%			70.00%											70.00%	70.00%
Mississippi Power [Member] | Kemper IGCC [Member] | Treetop Midstream Services, LLC, Contractor [Member]
Loss Contingencies [Line Items]
Long-term contract for purchase of percentage of carbon dioxide captured from plant			30.00%																				30.00%			30.00%											30.00%	30.00%
Mississippi Power [Member] | Kemper IGCC [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Loss contingency damages sought					$ 100,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Property, Plant and Equipment [Member]
Loss Contingencies [Line Items]
Estimated cost																										$ 3,700,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other Property And Investments [Member]
Loss Contingencies [Line Items]
Estimated cost																										6,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Fossil Fuel Stock [Member]
Loss Contingencies [Line Items]
Estimated cost																										81,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Materials And Supplies [Member]
Loss Contingencies [Line Items]
Estimated cost																										46,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other regulatory assets, current [Member]
Loss Contingencies [Line Items]
Estimated cost																										33,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other regulatory assets, deferred [Member]
Loss Contingencies [Line Items]
Estimated cost																										177,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other current assets [Member]
Loss Contingencies [Line Items]
Estimated cost																										4,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other deferred charges and assets [Member]
Loss Contingencies [Line Items]
Estimated cost																										9,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Current Assets [Member]
Loss Contingencies [Line Items]
Regulatory assets			$ 33,000,000																				$ 33,000,000			$ 33,000,000											$ 33,000,000	$ 33,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Estimated cost																																	2,880,000,000
Amortization period of regulatory assets and liabilities																										10 years
Mississippi Power [Member] | Kemper IGCC [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Amortization period of regulatory assets and liabilities																										2 years
Mississippi Power [Member] | Electricity Generation Plant, Non-Nuclear [Member]
Loss Contingencies [Line Items]
Estimated cost																						$ 2,400,000,000											$ 2,400,000,000
Alternate financing																																$ 1,000,000,000
Mississippi Power [Member] | Electricity Generation Plant, Non-Nuclear [Member] | Denbury Onshore, Contractor [Member]
Loss Contingencies [Line Items]
Long-term contract for purchase of carbon dioxide term						16 years
Mississippi Power [Member] | Mine [Member]
Loss Contingencies [Line Items]
Term of management fee contract																																		40 years
Alabama Power [Member]
Loss Contingencies [Line Items]
Maximum borrowing capacity			1,335,000,000																				1,335,000,000			$ 1,335,000,000											1,335,000,000	1,335,000,000
Construction work in progress			473,000,000							801,000,000													473,000,000			473,000,000				801,000,000							473,000,000	473,000,000
Allowance for equity funds used during construction																							7,000,000	$ 14,000,000		23,000,000	$ 43,000,000
Other Regulatory Assets Current			73,000,000							$ 115,000,000													73,000,000			73,000,000				$ 115,000,000							73,000,000	73,000,000
Alabama Power [Member] | Plant Greene County Units 1 And 2 [Member]
Loss Contingencies [Line Items]
Capacity of units ceased using coal | MW																		300
Georgia Power And Atlanta Gas Light Company [Member] | Scenario, Forecast [Member]
Loss Contingencies [Line Items]
Percentage basis net merger savings																																								40.00%
Storm Costs [Member] | Georgia Power [Member]
Loss Contingencies [Line Items]
Regulatory assets			94,000,000																				94,000,000			94,000,000											94,000,000	94,000,000
Subsequent Event [Member] | Georgia Power [Member]
Loss Contingencies [Line Items]
Estimate of possible loss	$ 240,000,000
Public utilities, approved return on equity percentage	10.00%
Subsequent Event [Member] | Gulf Power [Member]
Loss Contingencies [Line Items]
Public utilities, approved return on equity percentage		11.00%
Requested rate increase (decrease) amount		$ 106,800,000
Location One [Member] | Southern Company Gas [Member]
Loss Contingencies [Line Items]
Environmental remediation liability			$ 5,000,000																				$ 5,000,000			$ 5,000,000											$ 5,000,000	$ 5,000,000
Infrastructure Program [Member] | Southern Company Gas [Member]
Loss Contingencies [Line Items]
Number of States in which Entity Operates | state			6																				6			6											6	6
Infrastructure Program [Member] | Southern Company Gas [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Program Duration Period																										10 years
Infrastructure Program [Member] | Southern Company Gas [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Program Duration Period																										4 years

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Assets:
Alternative investments, fair value	$ 18
Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	393
Interest rate derivatives	19
Foreign currency derivatives	23
Nuclear decommissioning trusts	1,616
Cash equivalents	1,680
Other investments	10
Total	3,741
Liabilities:
Energy-related derivatives	541
Interest rate derivatives	7
Foreign currency derivatives	24
Contingent Consideration Classified as Equity, Fair Value Disclosure	18
Total	590
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Energy-related derivatives	203
Interest rate derivatives	0
Foreign currency derivatives	0
Nuclear decommissioning trusts	660
Cash equivalents	1,680
Other investments	9
Total	2,552
Liabilities:
Energy-related derivatives	267
Interest rate derivatives	0
Foreign currency derivatives	0
Contingent Consideration Classified as Equity, Fair Value Disclosure	0
Total	267
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	190
Interest rate derivatives	19
Foreign currency derivatives	23
Nuclear decommissioning trusts	938
Cash equivalents	0
Other investments	0
Total	1,170
Liabilities:
Energy-related derivatives	274
Interest rate derivatives	7
Foreign currency derivatives	24
Contingent Consideration Classified as Equity, Fair Value Disclosure	0
Total	305
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Foreign currency derivatives	0
Nuclear decommissioning trusts	0
Cash equivalents	0
Other investments	1
Total	1
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Foreign currency derivatives	0
Contingent Consideration Classified as Equity, Fair Value Disclosure	18
Total	18
Alabama Power [Member]
Assets:
Energy-related derivatives	8	$ 1
Alternative investments, fair value	18
Liabilities:
Energy-related derivatives	21	70
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	8
Cash equivalents	410
Total	1,199
Liabilities:
Energy-related derivatives	21
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	445
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	98
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	22
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	170
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	21
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Assets:
Nuclear decommissioning trusts	18
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	7
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Energy-related derivatives	0
Cash equivalents	410
Total	854
Liabilities:
Energy-related derivatives	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	373
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	49
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	22
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Private Equity Funds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	8
Cash equivalents	0
Total	327
Liabilities:
Energy-related derivatives	21
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	72
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	49
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	22
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	148
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	21
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Private Equity Funds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	7
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Cash equivalents	0
Total	0
Liabilities:
Energy-related derivatives	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Private Equity Funds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member]
Assets:
Energy-related derivatives	25	7
Nuclear decommissioning trusts	42
Liabilities:
Energy-related derivatives	16	21
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	15
Interest rate derivatives	10
Cash equivalents	32
Total	892
Liabilities:
Energy-related derivatives	16
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	198
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	125
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	59
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	70
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	172
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	149
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	62
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Cash equivalents	32
Total	248
Liabilities:
Energy-related derivatives	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	197
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	19
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	15
Interest rate derivatives	10
Cash equivalents	0
Total	644
Liabilities:
Energy-related derivatives	16
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	1
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	125
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	59
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	70
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	172
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	149
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	43
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Cash equivalents	0
Total	0
Liabilities:
Energy-related derivatives	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	0
Gulf Power [Member]
Assets:
Energy-related derivatives	1	1
Liabilities:
Energy-related derivatives	57	100
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	1
Cash equivalents	20
Total	21
Liabilities:
Energy-related derivatives	51
Interest rate derivatives	6
Total	57
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Energy-related derivatives	0
Cash equivalents	20
Total	20
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	1
Cash equivalents	0
Total	1
Liabilities:
Energy-related derivatives	51
Interest rate derivatives	6
Total	57
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Cash equivalents	0
Total	0
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Mississippi Power [Member]
Assets:
Energy-related derivatives	1
Liabilities:
Energy-related derivatives	22	47
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	1
Cash equivalents	137
Total	138
Liabilities:
Energy-related derivatives	21
Interest rate derivatives	1
Total	22
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Energy-related derivatives	0
Cash equivalents	137
Total	137
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	1
Cash equivalents	0
Total	1
Liabilities:
Energy-related derivatives	21
Interest rate derivatives	1
Total	22
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Cash equivalents	0
Total	0
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Southern Power [Member]
Assets:
Energy-related derivatives	26	7
Liabilities:
Energy-related derivatives	27	$ 3
Southern Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	3
Foreign currency derivatives	23
Cash equivalents	647
Total	673
Liabilities:
Energy-related derivatives	3
Foreign currency derivatives	24
Contingent Consideration Classified as Equity, Fair Value Disclosure	18
Total	45
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Energy-related derivatives	0
Foreign currency derivatives	0
Cash equivalents	647
Total	647
Liabilities:
Energy-related derivatives	0
Foreign currency derivatives	0
Contingent Consideration Classified as Equity, Fair Value Disclosure	0
Total	0
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	3
Foreign currency derivatives	23
Cash equivalents	0
Total	26
Liabilities:
Energy-related derivatives	3
Foreign currency derivatives	24
Contingent Consideration Classified as Equity, Fair Value Disclosure	0
Total	27
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Foreign currency derivatives	0
Cash equivalents	0
Total	0
Liabilities:
Energy-related derivatives	0
Foreign currency derivatives	0
Contingent Consideration Classified as Equity, Fair Value Disclosure	18
Total	18
Nuclear Decommissioning Trusts [Member]
Assets:
Alternative investments, fair value	18
Nuclear Decommissioning Trusts [Member] | Alabama Power [Member]
Assets:
Alternative investments, fair value	18
Weather Derivative [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	$ 7

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Measurements Of Investments Calculated At Net Asset Value Per Share (Details) $ in Millions	Sep. 30, 2016USD ($)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 18
Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	18
Unfunded Commitments	27
Alabama Power [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	18
Alabama Power [Member] | Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	18
Unfunded Commitments	$ 27

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments for which Carrying Amount did not Equal Fair Value (Details) $ in Millions	Sep. 30, 2016USD ($)
Southern Company [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	$ 43,668
Long-term debt, including securities due within one year, Fair Value	47,227
Alabama Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	7,091
Long-term debt, including securities due within one year, Fair Value	7,961
Georgia Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	10,398
Long-term debt, including securities due within one year, Fair Value	11,582
Gulf Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	1,184
Long-term debt, including securities due within one year, Fair Value	1,267
Mississippi Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	2,981
Long-term debt, including securities due within one year, Fair Value	2,967
Southern Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	4,608
Long-term debt, including securities due within one year, Fair Value	$ 4,821

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds	$ 49	$ (65)	$ 116	$ (33)
Private Equity Funds [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Liquidations term			10 years
Alabama Power [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds	26	(39)	$ 66	(19)
Georgia Power [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds	$ 23	$ (26)	$ 50	$ (14)
Southern Power [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Contingent Payment Obligations, Payment Period			10 years

Stockholders' Equity - Earnings

Stockholders' Equity - Earnings per Share (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Equity [Abstract]
As reported shares	968	910	940	910
Effect of options and performance share award units	7	2	5	3
Diluted shares	975	912	945	913
Stock options and performance share award units that were not included in the diluted earnings per share calculation (in shares)	0	15	0	1

Stockholders' Equity - Changes

Stockholders' Equity - Changes in Stockholders' Equity (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Changes in Stockholders' Equity
Beginning Balance, Treasury Shares			(3,400)
Beginning Balance			$ 21,982	$ 20,926
Consolidated net income attributable to Southern Company	$ 1,130	$ 959	2,226	2,096
Other comprehensive income (loss)	$ 22	(15)	(95)	(7)
Stock issued			3,265	136
Stock-based compensation			119	78
Stock repurchased, at cost				(115)
Cash dividends on common stock			(1,553)	(1,465)
Preference stock redemption				(150)
Contributions from noncontrolling interests			357	429
Distributions to noncontrolling interests			(21)	(13)
Purchase of membership interests from noncontrolling interests			(129)
Net income attributable to noncontrolling interests			36	13
Other			$ (7)	(5)
Beginning Balance, Treasury Shares	(800)		(800)
Ending Balance	$ 26,180	$ 21,923	$ 26,180	$ 21,923
Number of Common shares Issued [Member]
Changes in Stockholders' Equity
Beginning Balance, Shares			915,073	908,502
Stock issued, Shares			65,725	3,769
Ending Balance, Shares	980,798	912,271	980,798	912,271
Number of Common shares Treasury [Member]
Changes in Stockholders' Equity
Beginning Balance, Treasury Shares			(3,352)	(725)
Stock issued, Shares			2,599
Stock repurchased, at cost, Shares				(2,599)
Other, Shares			(46)	(8)
Beginning Balance, Treasury Shares	(799)	(3,332)	(799)	(3,332)
Common Stockholders' Equity [Member]
Changes in Stockholders' Equity
Beginning Balance			$ 20,592	$ 19,949
Consolidated net income attributable to Southern Company			2,226	2,096
Other comprehensive income (loss)			(95)	(7)
Stock issued			3,265	136
Stock-based compensation			119	78
Stock repurchased, at cost				(115)
Cash dividends on common stock			(1,553)	(1,465)
Other			(7)	(8)
Ending Balance	$ 24,547	$ 20,664	24,547	20,664
Preferred And Preference Stock [Member]
Changes in Stockholders' Equity
Beginning Balance			609	756
Preference stock redemption				(150)
Other				3
Ending Balance	609	609	609	609
Noncontrolling Interest [Member]
Changes in Stockholders' Equity
Beginning Balance			781	221
Contributions from noncontrolling interests			357	429
Distributions to noncontrolling interests			(21)	(13)
Purchase of membership interests from noncontrolling interests			(129)
Net income attributable to noncontrolling interests			36	13
Ending Balance	$ 1,024	$ 650	$ 1,024	$ 650

Financing - Schedule of Credit

Financing - Schedule of Credit Arrangements (Details)	Sep. 30, 2016USD ($)
Line of Credit Facility [Line Items]
Expires, 2016	$ 150,000,000
Expires, 2017	305,000,000
Expires, 2018	3,590,000,000
Expires, 2020	4,400,000,000
Total	8,445,000,000
Unused	8,281,000,000
Executable Term Loans, One Year	65,000,000
Executable Term Loans, Two Years	15,000,000
Due Within One Year, Term Out	80,000,000
Due Within One Year, No Term Out	300,000,000
Southern Company [Member]
Line of Credit Facility [Line Items]
Expires, 2016	0
Expires, 2017	0
Expires, 2018	1,000,000,000
Expires, 2020	1,250,000,000
Total	2,250,000,000
Unused	2,250,000,000
Executable Term Loans, One Year	0
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Alabama Power [Member]
Line of Credit Facility [Line Items]
Expires, 2016	0
Expires, 2017	35,000,000
Expires, 2018	500,000,000
Expires, 2020	800,000,000
Total	1,335,000,000
Unused	1,335,000,000
Executable Term Loans, One Year	0
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	35,000,000
Georgia Power [Member]
Line of Credit Facility [Line Items]
Expires, 2016	0
Expires, 2017	0
Expires, 2018	0
Expires, 2020	1,750,000,000
Total	1,750,000,000
Unused	1,732,000,000
Executable Term Loans, One Year	0
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Gulf Power [Member]
Line of Credit Facility [Line Items]
Expires, 2016	50,000,000
Expires, 2017	65,000,000
Expires, 2018	165,000,000
Expires, 2020	0
Total	280,000,000
Unused	280,000,000
Executable Term Loans, One Year	45,000,000
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	45,000,000
Due Within One Year, No Term Out	70,000,000
Mississippi Power [Member]
Line of Credit Facility [Line Items]
Expires, 2016	100,000,000
Expires, 2017	75,000,000
Expires, 2018	0
Expires, 2020	0
Total	175,000,000
Unused	150,000,000
Executable Term Loans, One Year	0
Executable Term Loans, Two Years	15,000,000
Due Within One Year, Term Out	15,000,000
Due Within One Year, No Term Out	160,000,000
Southern Power [Member]
Line of Credit Facility [Line Items]
Expires, 2016	0
Expires, 2017	0
Expires, 2018	0
Expires, 2020	600,000,000
Total	600,000,000
Unused	532,000,000
Executable Term Loans, One Year	0
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Southern Company Gas [Member]
Line of Credit Facility [Line Items]
Expires, 2016	0
Expires, 2017	75,000,000
Expires, 2018	1,925,000,000
Expires, 2020	0
Total	2,000,000,000
Unused	1,947,000,000
Executable Term Loans, One Year	0
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Other [Member]
Line of Credit Facility [Line Items]
Expires, 2016	0
Expires, 2017	55,000,000
Expires, 2018	0
Expires, 2020	0
Total	55,000,000
Unused	55,000,000
Executable Term Loans, One Year	20,000,000
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	20,000,000
Due Within One Year, No Term Out	35,000,000
Southern Company Gas Capital [Member]
Line of Credit Facility [Line Items]
Total	$ 1,300,000,000

Financing - Schedule of Line of

Financing - Schedule of Line of Credit Facilities (Details)	Sep. 30, 2016USD ($)
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 8,445,000,000
Remaining borrowing capacity	8,281,000,000
Southern Power [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	600,000,000
Remaining borrowing capacity	532,000,000
Southern Power [Member] | Construction Loans [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	235,000,000
Southern Power [Member] | Construction Loans [Member] | RE Garland Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	86,000,000
Southern Power [Member] | Construction Loans [Member] | RE Roserock Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	63,000,000
Southern Power [Member] | Construction Loans [Member] | RE Tranquility Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	86,000,000
Southern Power [Member] | Bridge Loan [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	660,000,000
Southern Power [Member] | Bridge Loan [Member] | RE Garland Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	308,000,000
Southern Power [Member] | Bridge Loan [Member] | RE Roserock Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	180,000,000
Southern Power [Member] | Bridge Loan [Member] | RE Tranquility Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	172,000,000
Southern Power [Member] | Construction Loan And Bridge Loan [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	895,000,000
Remaining borrowing capacity	67,000,000
Southern Power [Member] | Construction Loan And Bridge Loan [Member] | RE Garland Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	394,000,000
Remaining borrowing capacity	21,000,000
Southern Power [Member] | Construction Loan And Bridge Loan [Member] | RE Roserock Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	243,000,000
Remaining borrowing capacity	34,000,000
Southern Power [Member] | Construction Loan And Bridge Loan [Member] | RE Tranquility Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	258,000,000
Remaining borrowing capacity	12,000,000
Southern Power [Member] | Letter of Credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	149,000,000
Remaining borrowing capacity	65,000,000
Southern Power [Member] | Letter of Credit [Member] | RE Garland Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	49,000,000
Remaining borrowing capacity	23,000,000
Southern Power [Member] | Letter of Credit [Member] | RE Roserock Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	23,000,000
Remaining borrowing capacity	16,000,000
Southern Power [Member] | Letter of Credit [Member] | RE Tranquility Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	77,000,000
Remaining borrowing capacity	$ 26,000,000

Financing - Schedule of Long-Te

Financing - Schedule of Long-Term Debt Financing Activities (Details) - USD ($)	1 Months Ended	9 Months Ended
	May 31, 2016	Sep. 30, 2016
Debt Instrument [Line Items]
Senior Note Issuances		$ 11,981,000,000
Senior Note Maturities and Redemptions		1,825,000,000
Revenue Bond Maturities Redemptions and Repurchases		4,000,000
Other Long-Term Debt Issuances		2,110,000,000
Other Long-Term Debt Redemptions and Maturities		576,000,000
Consolidation, Eliminations [Member]
Debt Instrument [Line Items]
Senior Note Issuances		0
Senior Note Maturities and Redemptions		0
Revenue Bond Maturities Redemptions and Repurchases		0
Other Long-Term Debt Issuances		(200,000,000)
Other Long-Term Debt Redemptions and Maturities		(225,000,000)
Southern Company [Member]
Debt Instrument [Line Items]
Senior Note Issuances	$ 8,500,000,000	8,500,000,000
Senior Note Maturities and Redemptions		500,000,000
Revenue Bond Maturities Redemptions and Repurchases		0
Other Long-Term Debt Issuances		800,000,000
Other Long-Term Debt Redemptions and Maturities		0
Alabama Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		400,000,000
Senior Note Maturities and Redemptions		200,000,000
Revenue Bond Maturities Redemptions and Repurchases		0
Other Long-Term Debt Issuances		45,000,000
Other Long-Term Debt Redemptions and Maturities		0
Georgia Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		650,000,000
Senior Note Maturities and Redemptions		700,000,000
Revenue Bond Maturities Redemptions and Repurchases		4,000,000
Other Long-Term Debt Issuances		300,000,000
Other Long-Term Debt Redemptions and Maturities		5,000,000
Gulf Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		0
Senior Note Maturities and Redemptions		125,000,000
Revenue Bond Maturities Redemptions and Repurchases		0
Other Long-Term Debt Issuances		2,000,000
Other Long-Term Debt Redemptions and Maturities		0
Mississippi Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		0
Senior Note Maturities and Redemptions		0
Revenue Bond Maturities Redemptions and Repurchases		0
Other Long-Term Debt Issuances		1,100,000,000
Other Long-Term Debt Redemptions and Maturities		652,000,000
Southern Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		1,531,000,000
Senior Note Maturities and Redemptions		0
Revenue Bond Maturities Redemptions and Repurchases		0
Other Long-Term Debt Issuances		63,000,000
Other Long-Term Debt Redemptions and Maturities		84,000,000
Southern Company Gas [Member]
Debt Instrument [Line Items]
Senior Note Issuances		900,000,000
Senior Note Maturities and Redemptions		300,000,000
Revenue Bond Maturities Redemptions and Repurchases		0
Other Long-Term Debt Issuances		0
Other Long-Term Debt Redemptions and Maturities		0
Other [Member]
Debt Instrument [Line Items]
Senior Note Issuances		0
Senior Note Maturities and Redemptions		0
Revenue Bond Maturities Redemptions and Repurchases		0
Other Long-Term Debt Issuances		0
Other Long-Term Debt Redemptions and Maturities		$ 60,000,000

Financing - Narrative (Details)

Financing - Narrative (Details)	Jun. 27, 2016USD ($)	Mar. 08, 2016USD ($)	Jan. 28, 2016USD ($)	Sep. 30, 2016USD ($)	May 31, 2016USD ($)	Mar. 31, 2016USD ($)	Jan. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Jul. 10, 2016	Jul. 01, 2016USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2016EUR (€)	May 24, 2016USD ($)	Jan. 19, 2016USD ($)	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding				$ 1,900,000,000				$ 1,900,000,000	$ 1,900,000,000
Maximum borrowing capacity				8,445,000,000				8,445,000,000	8,445,000,000
Senior note issuances									11,981,000,000
Remaining borrowing capacity				8,281,000,000				8,281,000,000	8,281,000,000
Bridge Agreement [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity															$ 8,100,000,000
Southern Natural Gas Company, LLC [Member]
Debt Instrument [Line Items]
Noncontrolling interest, ownership percentage by parent											50.00%
Alabama Power [Member]
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding				890,000,000				890,000,000	890,000,000
Fixed rate pollution control revenue bonds outstanding				87,000,000				87,000,000	87,000,000
Maximum borrowing capacity				1,335,000,000				1,335,000,000	1,335,000,000
Senior note issuances									400,000,000
Repayments of senior debt									200,000,000	$ 250,000,000
Capital contributions									253,000,000	13,000,000
Remaining borrowing capacity				1,335,000,000				1,335,000,000	1,335,000,000
Alabama Power [Member] | Series FF [Member]
Debt Instrument [Line Items]
Debt stated interest rate							5.20%
Alabama Power [Member] | Senior Notes [Member] | Series 2016A [Member]
Debt Instrument [Line Items]
Debt face amount							$ 400,000,000
Debt stated interest rate							4.30%
Alabama Power [Member] | Unsecured Debt [Member] | Series FF [Member]
Debt Instrument [Line Items]
Repayments of senior debt							$ 200,000,000
Alabama Power [Member] | Bank Loans [Member]
Debt Instrument [Line Items]
Debt face amount						$ 45,000,000
Debt stated interest rate						2.38%
Georgia Power [Member]
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding				868,000,000				868,000,000	868,000,000
Fixed rate pollution control revenue bonds outstanding				250,000,000				250,000,000	250,000,000
Current borrowing capacity													$ 300,000,000
Maximum borrowing capacity				1,750,000,000				1,750,000,000	1,750,000,000
Senior note issuances									650,000,000
Repayments of senior debt									700,000,000	525,000,000
Capital contributions									294,000,000	41,000,000
Remaining borrowing capacity				1,732,000,000				1,732,000,000	1,732,000,000
Georgia Power [Member] | Senior Notes [Member] | Series 2016A [Member]
Debt Instrument [Line Items]
Debt face amount						$ 325,000,000
Debt stated interest rate						3.25%
Georgia Power [Member] | Senior Notes [Member] | Series 2016B [Member]
Debt Instrument [Line Items]
Debt face amount						$ 325,000,000
Debt stated interest rate						2.40%
Georgia Power [Member] | Unsecured Debt [Member] | Series 2013B [Member]
Debt Instrument [Line Items]
Repayments of senior debt						$ 250,000,000
Georgia Power [Member] | Line of Credit [Member] | FFB Credit Facility due 2044 [Member]
Debt Instrument [Line Items]
Debt stated interest rate													2.571%	2.571%
Gulf Power [Member]
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding				82,000,000				82,000,000	82,000,000
Fixed rate pollution control revenue bonds outstanding				21,000,000				21,000,000	21,000,000
Maximum borrowing capacity				280,000,000				280,000,000	280,000,000
Senior note issuances									0
Repayments of senior debt									125,000,000	60,000,000
Remaining borrowing capacity				280,000,000				280,000,000	280,000,000
Gulf Power [Member] | Series 2011A [Member]
Debt Instrument [Line Items]
Redemption amount of principal notes					$ 125,000,000
Gulf Power [Member] | Senior Notes [Member] | Series 2011A [Member]
Debt Instrument [Line Items]
Debt stated interest rate					5.75%
Gulf Power [Member] | Bank Loans [Member]
Debt Instrument [Line Items]
Debt face amount					$ 100,000,000
Debt instrument term					11 months
Nicor Gas [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				700,000,000				700,000,000	700,000,000
Mississippi Power [Member]
Debt Instrument [Line Items]
Variable rate pollution control revenue bonds outstanding				40,000,000				40,000,000	40,000,000
Current borrowing capacity				100,000,000				100,000,000	100,000,000							$ 100,000,000
Maximum borrowing capacity				175,000,000				175,000,000	175,000,000
Senior note issuances									0
Promissory note			$ 275,000,000						0	301,000,000
Capital contributions	$ 225,000,000								227,000,000	153,000,000
Long-term debt affiliated				551,000,000				551,000,000	551,000,000								$ 576,000,000
Remaining borrowing capacity				150,000,000				150,000,000	150,000,000
Mississippi Power [Member] | Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt face amount													$ 10,000,000
Mississippi Power [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt stated interest rate													2.35%	2.35%
Redemption amount of principal notes		$ 300,000,000
Mississippi Power [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Current borrowing capacity		900,000,000
Maximum borrowing capacity		1,200,000,000
Remaining borrowing capacity		300,000,000
Mississippi Power [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Repayments of senior debt		$ 900,000,000
Traditional Operating Companies [Member]
Debt Instrument [Line Items]
Fixed rate pollution control revenue bonds outstanding				358,000,000				358,000,000	358,000,000
Southern Power [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				600,000,000				600,000,000	600,000,000
Senior note issuances									1,531,000,000
Repayments of senior debt									0	525,000,000
Capital contributions									800,000,000	$ 226,000,000
Remaining borrowing capacity				532,000,000				532,000,000	532,000,000
Southern Power [Member] | Senior Notes [Member] | Series 2016A [Member]
Debt Instrument [Line Items]
Debt face amount | €														€ 600,000,000
Debt stated interest rate													1.00%	1.00%
Southern Power [Member] | Senior Notes [Member] | Series 2016B [Member]
Debt Instrument [Line Items]
Debt face amount | €														€ 500,000,000
Debt stated interest rate													1.85%	1.85%
Southern Power [Member] | Senior Notes [Member] | Series 2016C [Member]
Debt Instrument [Line Items]
Debt face amount				$ 290,000,000				$ 290,000,000	$ 290,000,000
Debt stated interest rate				2.75%				2.75%	2.75%
Southern Power [Member] | Bank Loans [Member]
Debt Instrument [Line Items]
Debt face amount				$ 60,000,000				$ 60,000,000	$ 60,000,000
Repayments of senior debt				80,000,000
Southern Power [Member] | Bank Loans [Member] | Debt Due 2016 [Member]
Debt Instrument [Line Items]
Debt face amount				400,000,000				400,000,000	400,000,000
Southern Power [Member] | Bank Loans [Member] | Debt Due 2018 [Member]
Debt Instrument [Line Items]
Debt face amount				320,000,000				320,000,000	320,000,000
Southern Power [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Debt face amount				34,000,000				34,000,000	34,000,000
Southern Power [Member] | Project Credit Facilities [Member]
Debt Instrument [Line Items]
Current borrowing capacity				$ 828,000,000				$ 828,000,000	$ 828,000,000
Weighted average interest rate				2.05%				2.05%	2.05%
Maximum borrowing capacity				$ 828,000,000				$ 828,000,000	$ 828,000,000
Average amount outstanding				805,000,000				$ 805,000,000	805,000,000
Interest rate during period								2.02%
Southern Power [Member] | Construction Loans [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				235,000,000				$ 235,000,000	235,000,000
Southern Power [Member] | Henrietta [Member]
Debt Instrument [Line Items]
Construction loan												$ 217,000,000
Southern Power [Member] | Henrietta [Member] | Construction Loans [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				217,000,000				217,000,000	217,000,000
Average amount outstanding				137,000,000				$ 137,000,000	137,000,000
Interest rate during period								2.21%
Southern Company [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				2,250,000,000				$ 2,250,000,000	2,250,000,000
Senior note issuances					$ 8,500,000,000				8,500,000,000
Remaining borrowing capacity				$ 2,250,000,000				$ 2,250,000,000	$ 2,250,000,000
Southern Company [Member] | Series 2011A [Member]
Debt Instrument [Line Items]
Debt stated interest rate				1.95%				1.95%	1.95%
Southern Company [Member] | Senior Notes [Member] | Senior Notes due July 1, 2018 [Member]
Debt Instrument [Line Items]
Debt face amount					$ 500,000,000
Debt stated interest rate					1.55%
Southern Company [Member] | Senior Notes [Member] | Senior Notes due July 1, 2019 [Member]
Debt Instrument [Line Items]
Debt face amount					$ 1,000,000,000
Debt stated interest rate					1.85%
Southern Company [Member] | Senior Notes [Member] | Senior Notes due July 1, 2021 [Member]
Debt Instrument [Line Items]
Debt face amount					$ 1,500,000,000
Debt stated interest rate					2.35%
Southern Company [Member] | Senior Notes [Member] | Senior Notes due July 1, 2023 [Member]
Debt Instrument [Line Items]
Debt face amount					$ 1,250,000,000
Debt stated interest rate					2.95%
Southern Company [Member] | Senior Notes [Member] | Senior Notes due July 1, 2026 [Member]
Debt Instrument [Line Items]
Debt face amount					$ 1,750,000,000
Debt stated interest rate					3.25%
Southern Company [Member] | Senior Notes [Member] | Senior Notes due July 1, 2036 [Member]
Debt Instrument [Line Items]
Debt face amount					$ 500,000,000
Debt stated interest rate					4.25%
Southern Company [Member] | Senior Notes [Member] | Senior Notes due July 1, 2046 [Member]
Debt Instrument [Line Items]
Debt face amount					$ 2,000,000,000
Debt stated interest rate					4.40%
Southern Company [Member] | Junior Subordinated Debt [Member] | Senior Notes Due 2076 [Member]
Debt Instrument [Line Items]
Debt face amount				$ 800,000,000				$ 800,000,000	$ 800,000,000
Debt stated interest rate				5.25%				5.25%	5.25%
Southern Company [Member] | Unsecured Debt [Member] | Series 2011A [Member]
Debt Instrument [Line Items]
Repayments of senior debt				$ 500,000,000
Southern Power's Subsidiary(ies) [Member]
Debt Instrument [Line Items]
Proceeds from long-term lines of credit									$ 691,000,000
Southern Power's Subsidiary(ies) [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Weighted average interest rate				2.05%				2.05%	2.05%
Southern Power's Subsidiary(ies) [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Debt face amount				$ 16,000,000				$ 16,000,000	$ 16,000,000
Southern Company Gas [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				2,000,000,000				2,000,000,000	2,000,000,000
Senior note issuances									900,000,000
Repayments of senior debt				120,000,000
Promissory note				360,000,000
Remaining borrowing capacity				1,947,000,000				1,947,000,000	1,947,000,000
Southern Company Gas [Member] | Senior Notes [Member] | Senior Notes due July 1, 2023 [Member]
Debt Instrument [Line Items]
Debt face amount				$ 350,000,000				$ 350,000,000	$ 350,000,000
Debt stated interest rate				2.45%				2.45%	2.45%
Southern Company Gas [Member] | Senior Notes [Member] | Senior Notes due July 1, 2046 [Member]
Debt Instrument [Line Items]
Debt face amount				$ 550,000,000				$ 550,000,000	$ 550,000,000
Debt stated interest rate				3.95%				3.95%	3.95%

Retirement Benefits (Details)

Retirement Benefits (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year				$ 0
Amortization:
Defined Benefit Plan, Contributions by Employer	$ 125,000,000
Pension Plans [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost		$ 68,000,000	$ 65,000,000	192,000,000	$ 193,000,000
Interest cost		110,000,000	111,000,000	311,000,000	333,000,000
Expected return on plan assets		(203,000,000)	(181,000,000)	(577,000,000)	(543,000,000)
Amortization:
Prior service costs		3,000,000	6,000,000	10,000,000	19,000,000
Net (gain)/loss		45,000,000	53,000,000	120,000,000	161,000,000
Net periodic pension cost		23,000,000	54,000,000	56,000,000	163,000,000
Pension Plans [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost		14,000,000	14,000,000	43,000,000	44,000,000
Interest cost		23,000,000	26,000,000	71,000,000	79,000,000
Expected return on plan assets		(46,000,000)	(44,000,000)	(138,000,000)	(133,000,000)
Amortization:
Prior service costs		1,000,000	2,000,000	2,000,000	5,000,000
Net (gain)/loss		10,000,000	14,000,000	30,000,000	41,000,000
Net periodic pension cost		2,000,000	12,000,000	8,000,000	36,000,000
Pension Plans [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost		17,000,000	18,000,000	52,000,000	54,000,000
Interest cost		34,000,000	38,000,000	102,000,000	115,000,000
Expected return on plan assets		(64,000,000)	(62,000,000)	(193,000,000)	(188,000,000)
Amortization:
Prior service costs		1,000,000	2,000,000	4,000,000	7,000,000
Net (gain)/loss		14,000,000	19,000,000	41,000,000	57,000,000
Net periodic pension cost		2,000,000	15,000,000	6,000,000	45,000,000
Pension Plans [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost		3,000,000	3,000,000	9,000,000	9,000,000
Interest cost		5,000,000	5,000,000	14,000,000	15,000,000
Expected return on plan assets		(9,000,000)	(8,000,000)	(26,000,000)	(24,000,000)
Amortization:
Prior service costs		0	1,000,000	1,000,000	1,000,000
Net (gain)/loss		2,000,000	2,000,000	5,000,000	7,000,000
Net periodic pension cost		1,000,000	3,000,000	3,000,000	8,000,000
Pension Plans [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost		3,000,000	3,000,000	9,000,000	9,000,000
Interest cost		4,000,000	5,000,000	14,000,000	16,000,000
Expected return on plan assets		(9,000,000)	(8,000,000)	(26,000,000)	(25,000,000)
Amortization:
Prior service costs		1,000,000	0	1,000,000	1,000,000
Net (gain)/loss		2,000,000	3,000,000	5,000,000	8,000,000
Net periodic pension cost		1,000,000	3,000,000	3,000,000	9,000,000
Other Postretirement Benefits [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost		6,000,000	6,000,000	17,000,000	17,000,000
Interest cost		20,000,000	20,000,000	55,000,000	59,000,000
Expected return on plan assets		(16,000,000)	(15,000,000)	(44,000,000)	(44,000,000)
Amortization:
Prior service costs		1,000,000	1,000,000	4,000,000	3,000,000
Net (gain)/loss		5,000,000	4,000,000	12,000,000	13,000,000
Net periodic pension cost		16,000,000	16,000,000	44,000,000	48,000,000
Other Postretirement Benefits [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost		1,000,000	1,000,000	4,000,000	4,000,000
Interest cost		5,000,000	5,000,000	14,000,000	15,000,000
Expected return on plan assets		(6,000,000)	(6,000,000)	(19,000,000)	(19,000,000)
Amortization:
Prior service costs		1,000,000	2,000,000	3,000,000	3,000,000
Net (gain)/loss		0	0	1,000,000	1,000,000
Net periodic pension cost		1,000,000	2,000,000	3,000,000	4,000,000
Other Postretirement Benefits [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost		2,000,000	2,000,000	5,000,000	5,000,000
Interest cost		7,000,000	9,000,000	22,000,000	26,000,000
Expected return on plan assets		(6,000,000)	(6,000,000)	(17,000,000)	(18,000,000)
Amortization:
Prior service costs		0	0	1,000,000	0
Net (gain)/loss		3,000,000	2,000,000	7,000,000	8,000,000
Net periodic pension cost		6,000,000	7,000,000	18,000,000	21,000,000
Other Postretirement Benefits [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost		0	1,000,000	1,000,000	1,000,000
Interest cost		1,000,000	0	2,000,000	2,000,000
Expected return on plan assets		0	0	(1,000,000)	(1,000,000)
Amortization:
Prior service costs		0	0	0	0
Net (gain)/loss		0	0	0	0
Net periodic pension cost		1,000,000	1,000,000	2,000,000	2,000,000
Other Postretirement Benefits [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost		0	0	1,000,000	1,000,000
Interest cost		0	1,000,000	2,000,000	3,000,000
Expected return on plan assets		0	0	(1,000,000)	(1,000,000)
Amortization:
Prior service costs		0	0	0	0
Net (gain)/loss		1,000,000	0	1,000,000	0
Net periodic pension cost		$ 1,000,000	$ 1,000,000	$ 3,000,000	$ 3,000,000

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 165		$ 188
Effective tax rate	29.10%	33.50%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of December 31, 2015	$ 433
Tax positions from current periods	12
Tax positions from prior periods	13
Balance as of September 30, 2016	458
Tax positions impacting the effective tax rate	20		10
Tax positions not impacting the effective tax rate	438		423
Kemper IGCC [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of September 30, 2016	438
Unrecognized tax benefit, associated interest	$ 24
Mississippi Power [Member]
Income Tax Contingency [Line Items]
Effective tax rate	(276.20%)	(20.90%)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of December 31, 2015	$ 421
Tax positions from current periods	0
Tax positions from prior periods	18
Balance as of September 30, 2016	439
Tax positions impacting the effective tax rate	1
Tax positions not impacting the effective tax rate	438
Mississippi Power [Member] | Kemper IGCC [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of September 30, 2016	438
Unrecognized tax benefit, associated interest	$ 24
Southern Power [Member]
Income Tax Contingency [Line Items]
Effective tax rate	(88.90%)	6.90%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of December 31, 2015	$ 8
Tax positions from current periods	12
Tax positions from prior periods	(1)
Balance as of September 30, 2016	19
Tax positions impacting the effective tax rate	19
Tax positions not impacting the effective tax rate	0
Investment Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax credit carryforward	1,200		554
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Tax positions not impacting the effective tax rate	94
General Business Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax credit carryforward	$ 26		$ 1

Derivatives - Energy-Related an

Derivatives - Energy-Related and Interest Rate Derivatives (Details) BTU in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)BTU
Interest Rate Contract [Member]
Interest rate derivatives
Notional Amount	$ 2,657
Fair Value Gain (Loss) at September 30, 2016	$ 12
Southern Company [Member] | Energy-related, Natural Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	540
Longest Hedge Date	2,020
Longest Non-Hedge Date	2,022
Southern Company [Member] | Interest Rate Contract [Member] | Maturity Date August 2017 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 250
Interest Rate Received	1.30%
Fair Value Gain (Loss) at September 30, 2016	$ 1
Southern Company [Member] | Interest Rate Contract [Member] | Maturity Date August 2017 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	0.17%
Southern Company [Member] | Interest Rate Contract [Member] | Maturity Date June 2020 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 300
Interest Rate Received	2.75%
Fair Value Gain (Loss) at September 30, 2016	$ 9
Southern Company [Member] | Interest Rate Contract [Member] | Maturity Date June 2020 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	0.92%
Alabama Power [Member] | Energy-related, Natural Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	75
Longest Hedge Date	2,020
Georgia Power [Member] | Energy-related, Natural Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	148
Longest Hedge Date	2,020
Georgia Power [Member] | Interest Rate Contract [Member] | Maturity Date June 2018 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 250
Interest Rate Received	5.40%
Fair Value Gain (Loss) at September 30, 2016	$ 2
Georgia Power [Member] | Interest Rate Contract [Member] | Maturity Date June 2018 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	4.02%
Georgia Power [Member] | Interest Rate Contract [Member] | Maturity Date December 2019 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 200
Interest Rate Received	4.25%
Fair Value Gain (Loss) at September 30, 2016	$ 5
Georgia Power [Member] | Interest Rate Contract [Member] | Maturity Date December 2019 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	2.46%
Georgia Power [Member] | Interest Rate Contract [Member] | Maturity Date December 2018 [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 500
Interest Rate Received	1.95%
Fair Value Gain (Loss) at September 30, 2016	$ 2
Georgia Power [Member] | Interest Rate Contract [Member] | Maturity Date December 2018 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Interest rate derivatives
Weighted Average Interest Rate Paid	0.76%
Gulf Power [Member] | Energy-related, Natural Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	57
Longest Hedge Date	2,020
Gulf Power [Member] | Interest Rate Contract [Member] | Maturity Date December 2026 [Member] | Cash Flow Hedges Of Forecasted Debt [Member]
Interest rate derivatives
Notional Amount	$ 80
Weighted Average Interest Rate Paid	2.32%
Fair Value Gain (Loss) at September 30, 2016	$ (6)
Mississippi Power [Member] | Energy-related, Natural Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	37
Longest Hedge Date	2,020
Mississippi Power [Member] | Interest Rate Contract [Member] | Maturity Date March 2018 [Member] | Cash Flow Hedges Of Existing Debt [Member]
Interest rate derivatives
Notional Amount	$ 900
Weighted Average Interest Rate Paid	0.79%
Fair Value Gain (Loss) at September 30, 2016	$ (1)
Southern Power [Member] | Energy-related, Natural Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	9
Longest Hedge Date	2,017
Longest Non-Hedge Date	2,016
Southern Power [Member] | Interest Rate Contract [Member] | Maturity Date October 2016 Number One [Member] | Not Designated as Hedging Instrument [Member]
Interest rate derivatives
Notional Amount	$ 65
Weighted Average Interest Rate Paid	2.50%
Fair Value Gain (Loss) at September 30, 2016	$ 0
Southern Power [Member] | Interest Rate Contract [Member] | Maturity Date October 2016 Number Two [Member] | Not Designated as Hedging Instrument [Member]
Interest rate derivatives
Notional Amount	$ 47
Weighted Average Interest Rate Paid	2.21%
Fair Value Gain (Loss) at September 30, 2016	$ 0
Southern Power [Member] | Interest Rate Contract [Member] | Maturity Date October 2016 [Member] | Not Designated as Hedging Instrument [Member]
Interest rate derivatives
Derivative term	15 years
Southern Power [Member] | Interest Rate Contract [Member] | Maturity Date November 2016 [Member] | Not Designated as Hedging Instrument [Member]
Interest rate derivatives
Notional Amount	$ 65
Weighted Average Interest Rate Paid	2.21%
Fair Value Gain (Loss) at September 30, 2016	$ 0
Derivative term	12 years
Southern Company Gas [Member] | Energy-related, Natural Gas [Member] | Long [Member] | Not Designated as Hedging Instrument [Member]
Energy-related derivative contracts
Derivative nonmonetary notional amount net long short position volume | BTU	3,200
Southern Company Gas [Member] | Energy-related, Natural Gas [Member] | Short [Member] | Not Designated as Hedging Instrument [Member]
Energy-related derivative contracts
Derivative nonmonetary notional amount net long short position volume | BTU	2,900

Derivatives - Foreign Currency

Derivatives - Foreign Currency Derivatives (Details) - 9 months ended Sep. 30, 2016 - Cash Flow Hedges Of Existing Debt [Member] - Foreign Exchange Contract [Member] € in Millions, $ in Millions	USD ($)	EUR (€)
Derivative [Line Items]
Pay Notional	$ 1,241
Receive Notional | €		€ 1,100
Fair Value Gain (Loss) at September 30, 2016	(1)
Southern Power [Member] | Maturity Date June 2022 [Member]
Derivative [Line Items]
Pay Notional	$ 677
Pay Rate	2.95%
Receive Notional | €		600
Receive Rate	1.00%
Fair Value Gain (Loss) at September 30, 2016	$ (2)
Southern Power [Member] | Maturity Date June 2026 [Member]
Derivative [Line Items]
Pay Notional	$ 564
Pay Rate	3.78%
Receive Notional | €		€ 500
Receive Rate	1.85%
Fair Value Gain (Loss) at September 30, 2016	$ 1

Derivatives - Derivative Financ

Derivatives - Derivative Financial Statement Presentation and Amounts With Balance Sheet Offsetting (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Southern Company [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	$ 442	$ 29
Derivatives, liabilities	(572)	(250)
Derivative asset amount offset	(283)
Derivative liability amount offset	394
Derivative Asset	159
Derivative Liability	(178)
Southern Company [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		7
Derivatives, liabilities		(220)
Southern Company [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		22
Derivatives, liabilities		(30)
Southern Company [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	363	4
Derivatives, liabilities	(419)
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	305	1
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	58
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(345)	(1)
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(74)
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		3
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	33
Derivatives, liabilities	(115)	(217)
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	20	3
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	13
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(62)	(130)
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(53)	(87)
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	46	22
Derivatives, liabilities	(38)	(32)
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	4	3
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(6)	(2)
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(1)
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	8	19
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	11
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(7)	(23)
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	(7)
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	23
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(24)
Alabama Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	8	1
Derivatives, liabilities	(21)	(70)
Derivative asset amount offset	(7)
Derivative liability amount offset	7
Derivative Asset	1
Derivative Liability	(14)
Alabama Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		1
Derivatives, liabilities		(55)
Alabama Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Derivatives, liabilities		(15)
Alabama Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	8
Derivatives, liabilities	(21)	(55)
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	4	1
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	4
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(14)	(40)
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(7)	(15)
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Derivatives, liabilities		(15)
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		(15)
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Georgia Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	25	7
Derivatives, liabilities	(16)	(21)
Derivative asset amount offset	(11)
Derivative liability amount offset	11
Derivative Asset	14
Derivative Liability	(5)
Georgia Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		2
Derivatives, liabilities		(15)
Georgia Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		5
Derivatives, liabilities		(6)
Georgia Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	15
Derivatives, liabilities	(16)	(15)
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	7	2
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	8
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		(12)
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(11)	(3)
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(5)
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	10	5
Derivatives, liabilities	0	(6)
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	5	5
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	5
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	(6)
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Gulf Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	1
Derivatives, liabilities	(57)	(100)
Derivative asset amount offset	(1)
Derivative liability amount offset	1
Derivative Asset	0
Derivative Liability	(56)
Gulf Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Derivatives, liabilities		(100)
Gulf Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		1
Derivatives, liabilities		0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Derivatives, liabilities	(51)	(100)
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(24)	(49)
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(27)	(51)
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		1
Derivatives, liabilities		0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	1
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(6)	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Derivatives, liabilities	(22)	(47)
Derivative asset amount offset	(1)
Derivative liability amount offset	1
Derivative Asset	0
Derivative Liability	(21)
Mississippi Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Derivatives, liabilities		(47)
Mississippi Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Derivatives, liabilities		0
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Derivatives, liabilities	(21)	(47)
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		(29)
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(8)	(18)
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(13)
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(1)
Southern Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	26	7
Derivatives, liabilities	(27)	(3)
Derivative asset amount offset	(1)
Derivative liability amount offset	1
Derivative Asset	25
Derivative Liability	(26)
Southern Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		4
Derivatives, liabilities		(3)
Southern Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		3
Derivatives, liabilities		0
Southern Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		4
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		1
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		(1)
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		3
Southern Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	25	3
Derivatives, liabilities	(27)	(2)
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	3
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		(2)
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	(3)
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		$ 0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	23
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	$ (24)

Derivatives - Balance Sheet Off

Derivatives - Balance Sheet Offsetting (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Southern Company [Member]
Derivative [Line Items]
Derivatives, assets	$ 442	$ 29
Derivatives, liabilities	572	250
Southern Company [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets		1
Net interest rate derivative liabilities		214
Southern Company [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		7
Derivatives, liabilities		220
Southern Company [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		(6)
Gross amounts not offset in the Balance Sheet, liabilities		(6)
Southern Company [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets		13
Net interest rate derivative liabilities		21
Southern Company [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		22
Derivatives, liabilities		30
Southern Company [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		(9)
Gross amounts not offset in the Balance Sheet, liabilities		(9)
Alabama Power [Member]
Derivative [Line Items]
Derivatives, assets	8	1
Derivatives, liabilities	21	70
Alabama Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets		0
Net interest rate derivative liabilities		54
Alabama Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		1
Derivatives, liabilities		55
Alabama Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		(1)
Gross amounts not offset in the Balance Sheet, liabilities		(1)
Alabama Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets		0
Net interest rate derivative liabilities		15
Alabama Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		0
Derivatives, liabilities		15
Alabama Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		0
Gross amounts not offset in the Balance Sheet, liabilities		0
Georgia Power [Member]
Derivative [Line Items]
Derivatives, assets	25	7
Derivatives, liabilities	16	21
Georgia Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets		0
Net interest rate derivative liabilities		13
Georgia Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		2
Derivatives, liabilities		15
Georgia Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		(2)
Gross amounts not offset in the Balance Sheet, liabilities		(2)
Georgia Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets		1
Net interest rate derivative liabilities		2
Georgia Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		5
Derivatives, liabilities		6
Georgia Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		(4)
Gross amounts not offset in the Balance Sheet, liabilities		(4)
Gulf Power [Member]
Derivative [Line Items]
Derivatives, assets	1	1
Derivatives, liabilities	57	100
Gulf Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets		0
Net interest rate derivative liabilities		100
Gulf Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		0
Derivatives, liabilities		100
Gulf Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		0
Gross amounts not offset in the Balance Sheet, liabilities		0
Gulf Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets		1
Net interest rate derivative liabilities		0
Gulf Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		1
Derivatives, liabilities		0
Gulf Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		0
Gross amounts not offset in the Balance Sheet, liabilities		0
Mississippi Power [Member]
Derivative [Line Items]
Derivatives, assets	1
Derivatives, liabilities	22	47
Mississippi Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets		0
Net interest rate derivative liabilities		47
Mississippi Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		0
Derivatives, liabilities		47
Mississippi Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		0
Gross amounts not offset in the Balance Sheet, liabilities		0
Mississippi Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets		0
Net interest rate derivative liabilities		0
Mississippi Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		0
Derivatives, liabilities		0
Mississippi Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		0
Gross amounts not offset in the Balance Sheet, liabilities		0
Southern Power [Member]
Derivative [Line Items]
Derivatives, assets	26	7
Derivatives, liabilities	$ 27	3
Southern Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets		3
Net interest rate derivative liabilities		2
Southern Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		4
Derivatives, liabilities		3
Southern Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		(1)
Gross amounts not offset in the Balance Sheet, liabilities		(1)
Southern Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets		3
Net interest rate derivative liabilities		0
Southern Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives, assets		3
Derivatives, liabilities		0
Southern Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets		0
Gross amounts not offset in the Balance Sheet, liabilities		$ 0

Derivatives - Pre-tax Effects o

Derivatives - Pre-tax Effects of Derivatives Designated as Cash Flow Hedging Instruments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Southern Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	$ 31	$ (28)	$ (191)	$ (26)
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(4)	(2)	(32)	(7)
Southern Company [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(85)		(85)		$ (214)
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	0	(1)	0
Southern Company [Member] | Energy Related Derivative [Member] | Amortization [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	1	0	1	0
Southern Company [Member] | Energy Related Derivative [Member] | Other regulatory assets, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(52)		(52)		(130)
Southern Company [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(42)		(42)		(87)
Southern Company [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	8		8		3
Southern Company [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	1		1
Southern Company [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(6)	(28)	(189)	(26)
Southern Company [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(6)	(2)	(13)	(7)
Southern Company [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	37	0		0
Southern Company [Member] | Foreign Exchange Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(6)	0	(7)	0
Southern Company [Member] | Foreign Exchange Contract [Member] | Other Income Expense Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	7	0	(13)	0
Alabama Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(13)		(13)		(54)
Alabama Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(10)		(10)		(40)
Alabama Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(4)		(4)		(15)
Alabama Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	1		1		1
Alabama Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	0		0
Alabama Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	(10)	(3)	(9)
Alabama Power [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(2)	(1)	(5)	(2)
Georgia Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(1)		(1)		(13)
Georgia Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(2)		(2)		(12)
Georgia Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(4)		(4)		(3)
Georgia Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	4		4		2
Georgia Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	1		1
Georgia Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	(18)	0	(17)
Georgia Power [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(1)	(1)	(3)	(3)
Gulf Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(50)		(50)		(100)
Gulf Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(24)		(24)		(49)
Gulf Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(26)		(26)		(51)
Gulf Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	0		0		0
Gulf Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	0		0
Gulf Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)			(7)	0
Gulf Power [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)			0	0
Mississippi Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(21)		(21)		(47)
Mississippi Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(13)		(13)		(29)
Mississippi Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(8)		(8)		(18)
Mississippi Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	0		0		$ 0
Mississippi Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	0		0
Mississippi Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)			(1)	0
Mississippi Power [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)			(1)	(1)
Southern Power [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	37	0	(2)	0
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	2	0	(20)	(1)
Southern Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	0	(1)	0
Southern Power [Member] | Energy Related Derivative [Member] | Amortization [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	1	0	1	0
Southern Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)			0	0
Southern Power [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)			(1)	(1)
Southern Power [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	37	0	(1)	0
Southern Power [Member] | Foreign Exchange Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(6)	0	(7)	0
Southern Power [Member] | Foreign Exchange Contract [Member] | Other Income Expense Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ 7	$ 0	$ (13)	$ 0

Derivatives - Pre-tax Effects55

Derivatives - Pre-tax Effects of Derivatives as Fair Value Hedging Relationships (Details) - Interest Rate Contract [Member] - Interest Expense [Member] - Fair Value Hedging [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Southern Company [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets, Fair Value, Gross Asset	$ (9)	$ 15	$ 15	$ 19
Georgia Power [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets, Fair Value, Gross Asset	$ (5)	$ 7	$ 10	$ 9

Derivatives - Narrative (Detail

Derivatives - Narrative (Details) BTU in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)BTU
Derivative [Line Items]
Collateral already posted, aggregate fair value | $	$ 111
Maximum potential collateral requirements arising from credit risk related contingent features | $	$ 22
Parent Company And Georgia Power [Member]
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | BTU	5
Southern Company [Member]
Derivative [Line Items]
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months | $	$ (21)
Parent Company and Southern Power [Member]
Derivative [Line Items]
Foreign currency cash flow hedge gain (loss) to be reclassified during next 12 months | $	$ (12)
Energy-related, Natural Gas [Member] | Georgia Power [Member]
Derivative [Line Items]
Net quantity Purchase of Derivatives not designated as hedges | BTU	148
Energy-related, Natural Gas [Member] | Southern Power [Member]
Derivative [Line Items]
Net quantity Purchase of Derivatives not designated as hedges | BTU	9
Energy-related, Natural Gas [Member] | Southern Company [Member]
Derivative [Line Items]
Net quantity Purchase of Derivatives not designated as hedges | BTU	540

Acquisitions - Schedule of Acqu

Acquisitions - Schedule of Acquisitions (Details) $ in Millions	Oct. 26, 2016MW	Aug. 26, 2016MW	Jul. 01, 2016MW	Jun. 30, 2016MW	Apr. 07, 2016MW	Mar. 04, 2016MW	Feb. 11, 2016MW	Sep. 30, 2016USD ($)	Dec. 31, 2015USD ($)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill								$ 6,223	$ 2
Southern Company Gas [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Current assets								1,557
Property, plant, and equipment								10,108
Goodwill								5,937
Intangible assets								400
Regulatory assets								1,118
Other assets								229
Current liabilities								(2,201)
Deferred credits and other liabilities								(4,712)
Long-term debt								(4,261)
Noncontrolling interests								(174)
Total purchase price								8,001
PowerSecure International, Inc. [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Current assets								172
Property, plant, and equipment								46
Goodwill								284
Intangible assets								101
Other assets								6
Current liabilities								(145)
Long-term debt, including current portion								(18)
Deferred credits and other liabilities								(17)
Total purchase price								429
Southern Power [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability								30	36
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill								2	$ 2
Southern Power [Member] | Calipatria [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Approx. nameplate capacity, solar (MW) | MW							20
Southern Power Percentage Ownership							90.00%
PPA Contract Period							20 years
Southern Power [Member] | East Pecos [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Approx. nameplate capacity, solar (MW) | MW						120
Southern Power Percentage Ownership						100.00%
PPA Contract Period						15 years
Southern Power [Member] | Grant Plains [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Approx. nameplate capacity, wind (MW) | MW		147
Southern Power Percentage Ownership		100.00%
PPA Contract Period		12 years
Southern Power [Member] | Grant Wind, LLC [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Approx. nameplate capacity, wind (MW) | MW					151
Southern Power Percentage Ownership					100.00%
PPA Contract Period					20 years
Southern Power [Member] | Henrietta [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Approx. nameplate capacity, solar (MW) | MW			102
Southern Power Percentage Ownership			51.00%
PPA Contract Period			20 years
Southern Power [Member] | Lamesa [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Approx. nameplate capacity, solar (MW) | MW			102
Southern Power Percentage Ownership			100.00%
PPA Contract Period			15 years
Southern Power [Member] | Passadumkeag [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Approx. nameplate capacity, wind (MW) | MW				42
Southern Power Percentage Ownership				100.00%
PPA Contract Period				15 years
Southern Power [Member] | Rutherford [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Approx. nameplate capacity, solar (MW) | MW			74
Southern Power Percentage Ownership			90.00%
PPA Contract Period			15 years
Southern Power [Member] | Series of Business Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability								$ 145
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
PPA Contract Period								20 years
Southern Power [Member] | Series of Business Acquisitions [Member] | Class A Membership Interest [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Southern Power Percentage Ownership								100.00%
Percentage of entitled cash distributions								51.00%
Southern Power [Member] | Subsequent Event [Member] | Mankato [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Southern Power Percentage Ownership	100.00%
PPA Contract Period	10 years
Capacity of Natural Gas Facility | MW	375
Southern Power [Member] | Subsequent Event [Member] | Mankato Expansion [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
PPA Contract Period	20 years
Capacity of Natural Gas Facility | MW	345
Southern Power [Member] | Subsequent Event [Member] | Wake Wind [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Approx. nameplate capacity, wind (MW) | MW	257
Southern Power Percentage Ownership	90.10%
PPA Contract Period	12 years
SunPower Corp. [Member] | Series of Business Acquisitions [Member] | Class B Membership Interest [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Percentage of entitled cash distributions								49.00%
Recurrent Energy [Member] | Series of Business Acquisitions [Member] | Class B Membership Interest [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Southern Power Percentage Ownership								100.00%
Oklahoma Municipal Power Authority [Member] | Southern Power [Member] | Grant Plains [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
PPA Contract Period		20 years
Steelcase, Inc. [Member] | Southern Power [Member] | Grant Plains [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
PPA Contract Period		12 years
Allianz Risk Transfer (Bermuda) Ltd. [Member] | Southern Power [Member] | Grant Plains [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
PPA Contract Period		10 years

Acquisitions - Schedule of Cons

Acquisitions - Schedule of Construction Projects (Details) - MW	1 Months Ended							7 Months Ended	9 Months Ended
	Dec. 31, 2016	Nov. 30, 2016	Oct. 31, 2016	Aug. 31, 2016	Jul. 31, 2016	Mar. 31, 2016	Feb. 29, 2016	Jul. 31, 2016	Sep. 30, 2016	Mar. 29, 2016	Dec. 31, 2015
Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. nameplate capacity, solar (MW)					299			299	299
PPA Contract Period								20 years
Noncontrolling interest, ownership percentage by parent										15.00%
Capacity of small power production facility									189		110
Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member]
Business Acquisition [Line Items]
PPA Contract Period				20 years
Southern Power [Member] | RE Tranquility Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. nameplate capacity, solar (MW)				20	205	30	22	205
PPA Contract Period					18 years	30 years	20 years
Southern Power [Member] | Series of Business Acquisitions [Member]
Business Acquisition [Line Items]
PPA Contract Period									20 years
Class A Membership Interest [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Percentage of entitled cash distributions										66.00%
Class A Membership Interest [Member] | Southern Power [Member] | Series of Business Acquisitions [Member]
Business Acquisition [Line Items]
Noncontrolling interest, ownership percentage by parent									100.00%
Percentage of entitled cash distributions									51.00%
Class B Membership Interest [Member] | First Solar [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Percentage of entitled cash distributions										34.00%
Scenario, Forecast [Member] | Southern Power [Member] | Butler Solar LLC [Member]
Business Acquisition [Line Items]
Approx. nameplate capacity, solar (MW)	103
PPA Contract Period	30 years
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. nameplate capacity, solar (MW)			185
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland Holdings, LLC [Member]
Business Acquisition [Line Items]
PPA Contract Period			15 years
Scenario, Forecast [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. nameplate capacity, solar (MW)		160
PPA Contract Period		20 years
Scenario, Forecast [Member] | Southern Power [Member] | Sandhills [Member]
Business Acquisition [Line Items]
Approx. nameplate capacity, solar (MW)			146
PPA Contract Period			25 years

Acquisitions - Schedule of Pro

Acquisitions - Schedule of Pro Forma Consolidated Information (Details) - Southern Company Gas [Member] - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Business Acquisition [Line Items]
Operating revenues	$ 16,609	$ 16,865
Net income attributable to Southern Company	$ 2,369	$ 2,269
Basic EPS (in dollars per share)	$ 2.50	$ 2.43
Diluted EPS (in dollars per share)	$ 2.48	$ 2.42

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) $ / shares in Units, $ in Millions

Oct. 26, 2016USD ($)MW

Sep. 01, 2016USD ($)

Aug. 26, 2016MW

Jul. 01, 2016USD ($)MW

May 09, 2016USD ($)$ / shares

Feb. 11, 2016MW

Jan. 31, 2017MW

Nov. 30, 2016MW

Nov. 04, 2016USD ($)

Dec. 31, 2016entitiesMW

Sep. 30, 2016USD ($)MW

Sep. 30, 2015USD ($)

Jan. 31, 2017USD ($)MW

Jul. 31, 2016MW

Sep. 30, 2016USD ($)MW

Sep. 30, 2015USD ($)

Oct. 24, 2016MW

Jul. 10, 2016mi

Mar. 29, 2016

Dec. 31, 2015USD ($)

Business Acquisition [Line Items]

Goodwill

$ 6,223

$ 6,223

$ 2

Revenues

6,264

$ 5,401

14,715

$ 13,921

Consolidated net income attributable to Southern Company

1,130

959

2,226

2,096

Construction work in progress

10,069

10,069

9,082

Property, plant, and equipment

94,174

94,174

75,118

Intangible assets, net

942

942

317

Other current assets

168

168

71

Southern Company Gas [Member]

Business Acquisition [Line Items]

Revenues

543

Consolidated net income attributable to Southern Company

4

Southern Power and Turner Renewable Energy [Member]

Business Acquisition [Line Items]

Aggregate purchase price

923

Construction debt assumed

217

217

Southern Power [Member]

Business Acquisition [Line Items]

Aggregate purchase price

830

Goodwill

2

2

2

Revenues

500

$ 401

1,189

$ 1,086

Business Combination, Contingent Consideration, Liability

30

30

36

Construction work in progress

1,652

1,652

1,137

Property, plant, and equipment

9,491

9,491

7,275

Intangible assets, net

389

389

317

Other current assets

32

32

30

Other accounts payable

$ 218

218

$ 327

Total costs of construction

$ 3,000

Subsequent Event [Member]

Business Acquisition [Line Items]

Capacity Of Fuel Cell Systems | MW

50

Subsequent Event [Member] | Southern Power and Turner Renewable Energy [Member]

Business Acquisition [Line Items]

Aggregate purchase price

$ 924

Subsequent Event [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Aggregate purchase price

$ 873

East Pecos [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

100.00%

Life output of plant

12 years

Approx. nameplate capacity, wind (MW) | MW

147

Desert Stateline Holdings, LLC [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

15.00%

Life output of plant

20 years

Approx. nameplate capacity, solar (MW) | MW

299

299

299

Southern Company Gas [Member]

Business Acquisition [Line Items]

Aggregate purchase price

$ 8,000

Goodwill

$ 5,937

$ 5,937

Construction debt assumed

2,201

$ 2,201

Southern Company Gas [Member] | Minimum [Member]

Business Acquisition [Line Items]

Estimated lives of intangible assets

1 year

Southern Company Gas [Member] | Maximum [Member]

Business Acquisition [Line Items]

Estimated lives of intangible assets

28 years

Southern Company Gas [Member] | Bridge Agreement [Member]

Business Acquisition [Line Items]

Acquisition-related costs

40.8

$ 104.1

Southern Company Gas [Member] | Bridge Agreement [Member] | Operating Expense [Member]

Business Acquisition [Line Items]

Acquisition-related costs

40.6

73.5

Southern Company Gas [Member] | Bridge Agreement [Member] | Other Income Expense Net [Member]

Business Acquisition [Line Items]

Acquisition-related costs

0.2

30.6

PowerSecure International, Inc. [Member]

Business Acquisition [Line Items]

Aggregate purchase price

$ 429

Goodwill

284

284

Acquisition, share price (in dollars per share) | $ / shares

$ 18.75

Construction debt assumed

$ 145

$ 145

PowerSecure International, Inc. [Member] | Minimum [Member]

Business Acquisition [Line Items]

Estimated lives of intangible assets

1 year

PowerSecure International, Inc. [Member] | Maximum [Member]

Business Acquisition [Line Items]

Estimated lives of intangible assets

26 years

Southern Natural Gas Company, LLC [Member]

Business Acquisition [Line Items]

Aggregate purchase price

$ 1,400

Noncontrolling interest, ownership percentage by parent

50.00%

Pipeline Infrastructure (in miles) | mi

7,000

Piedmont [Member] | Southern Company Gas [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

15.00%

15.00%

Piedmont [Member] | Subsequent Event [Member] | Southern Company Gas [Member]

Business Acquisition [Line Items]

Aggregate purchase price

$ 160

Southstar [Member] | Southern Company Gas [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

85.00%

85.00%

Series of Business Acquisitions [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Business Combination, Contingent Consideration, Liability

$ 145

$ 145

Construction work in progress

1,000

1,000

Property, plant, and equipment

58

58

Intangible assets, net

77

77

Amortization expense remainder of fiscal year

1

1

Amortization expense next twelve months

4

4

Amortization expense year two

4

4

Amortization expense year three

4

4

Amortization expense year four

4

4

Amortization expense year five

4

4

Other current assets

24

24

Other accounts payable

5

$ 5

Life output of plant

20 years

Revenue of acquirees, actual

$ 14

Series of Business Acquisitions [Member] | Minimum [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Estimated future construction payments

708

708

Series of Business Acquisitions [Member] | Maximum [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Estimated future construction payments

$ 775

$ 775

Calipatria [Member] | Turner Renewable Energy [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

10.00%

10.00%

Calipatria [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

90.00%

Life output of plant

20 years

Approx. nameplate capacity, solar (MW) | MW

20

Henrietta [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

51.00%

Life output of plant

20 years

Approx. nameplate capacity, solar (MW) | MW

102

Henrietta [Member] | SunPower AssetCo, LLC [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

49.00%

49.00%

Rutherford [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

90.00%

Life output of plant

15 years

Approx. nameplate capacity, solar (MW) | MW

74

Rutherford [Member] | Subsequent Event [Member] | Turner Renewable Energy [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

9.90%

Mankato [Member] | Subsequent Event [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Capacity of Natural Gas Facility | MW

375

Noncontrolling interest, ownership percentage by parent

100.00%

Life output of plant

10 years

Mankato [Member] | Subsequent Event [Member] | Minimum [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Estimated future construction payments

$ 170

Mankato [Member] | Subsequent Event [Member] | Maximum [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Estimated future construction payments

$ 190

Mankato Expansion [Member] | Subsequent Event [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Capacity of Natural Gas Facility | MW

345

Life output of plant

20 years

Series of Construction Projects [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Construction work in progress

$ 1,200

$ 1,200

Series of Construction Projects [Member] | Minimum [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Estimated future construction payments

3,100

3,100

Series of Construction Projects [Member] | Maximum [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Estimated future construction payments

$ 3,200

$ 3,200

Scenario, Forecast [Member] | Series of Business Acquisitions [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Aggregate purchase price

$ 1,200

Scenario, Forecast [Member] | Business Acquisition, Solar [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

51.00%

Life output of plant

20 years

Approx. nameplate capacity, solar (MW) | MW

100

Scenario, Forecast [Member] | Series of Business Acquisitions, Wind [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

100.00%

Number of Businesses Acquired | entities

2

Approx. nameplate capacity, wind (MW) | MW

299

Scenario, Forecast [Member] | Series of Business Acquisitions, Wind [Member] | Minimum [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Life output of plant

12 years

Scenario, Forecast [Member] | Series of Business Acquisitions, Wind [Member] | Maximum [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Life output of plant

14 years

Scenario, Forecast [Member] | Business Acquisition, Wind [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

100.00%

100.00%

Life output of plant

12 years

Approx. nameplate capacity, wind (MW) | MW

275

275

Class A Membership Interest [Member] | Series of Business Acquisitions [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

100.00%

100.00%

Class A Membership Interest [Member] | Scenario, Forecast [Member] | Business Acquisition, Solar [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Noncontrolling interest, ownership percentage by parent

100.00%

Oklahoma Municipal Power Authority [Member] | East Pecos [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Life output of plant

20 years

Steelcase, Inc. [Member] | East Pecos [Member] | Southern Power [Member]

Business Acquisition [Line Items]

Life output of plant

12 years

Segment and Related Informati61

Segment and Related Information - Financial Data for Business Segments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)state	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)stateutilitiy	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of States in which Entity Operates | state	4		4
Operating revenues	$ 6,264	$ 5,401	$ 14,715	$ 13,921
Segment net income (loss)	1,130	959	2,226	2,096
Total assets	106,362		106,362		$ 78,318
Kemper IGCC [Member]
Segment Reporting Information [Line Items]
Pre-Tax Charge To Income	88	150	222	182
After Tax Charge To Income	54	93	137	112
Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,619	5,390	13,979	13,887
Segment net income (loss)	1,194	976	2,391	2,093
Total assets	83,359		83,359		77,560
Intersegment Eliminations [Member] | Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	(117)	(109)	(330)	(322)
Segment net income (loss)	0	0	0	0
Total assets	(440)		(440)		(397)
Consolidation Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	(37)	(26)	(118)	(86)
Segment net income (loss)	(1)	1	(8)	0
Total assets	(1,156)		(1,156)		(1,061)
Southern Company Gas [Member] | Natural Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	543		543
Segment net income (loss)	4		4
Total assets	21,185		21,185
Traditional Operating Companies [Member] | Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,236	5,098	13,120	13,123
Segment net income (loss)	1,018	874	2,076	1,912
Total assets	71,448		71,448		69,052
Southern Power [Member] | Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	500	401	1,189	1,086
Segment net income (loss)	176	102	315	181
Total assets	12,351		12,351		8,905
All Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	139	37	311	120
Segment net income (loss)	(67)	(18)	(161)	3
Total assets	2,974		$ 2,974		1,819
Southern Company Gas [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | utilitiy			7
Operating revenues	543
Segment net income (loss)	4
Southern Power [Member]
Segment Reporting Information [Line Items]
Wholesale revenues, affiliates	110	104	$ 313	303
Operating revenues	500	$ 401	1,189	$ 1,086
Total assets	$ 12,351		$ 12,351		$ 8,905

Segment and Related Informati62

Segment and Related Information - Financial Data for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue from External Customer [Line Items]
Gas Revenue	$ 543		$ 543
Electric Utilities' Revenues	5,619	$ 5,390	13,979	$ 13,887
Retail [Member]
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	4,808	4,701	11,932	11,958
Wholesale [Member]
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	613	520	1,455	1,435
Other [Member]
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	198	$ 169	592	$ 494
Gas Distribution Operations [Member]
Revenue from External Customer [Line Items]
Gas Revenue	420		420
Gas Marketing Services [Member]
Revenue from External Customer [Line Items]
Gas Revenue	126		126
Other Gas Revenue [Member]
Revenue from External Customer [Line Items]
Gas Revenue	$ (3)		$ (3)