Alabama Power (ALP-PQ) 10-Q 5 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	9 Months Ended
	Sep. 30, 2015shares
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, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	908,938,919
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, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating Revenues:
Total operating revenues	$ 5,401	$ 5,339	$ 13,921	$ 14,450
Other Income and (Expense):
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	959	718	2,096	1,680
Southern Company [Member]
Operating Revenues:
Retail revenues	4,701	4,558	11,958	12,186
Wholesale revenues	520	600	1,435	1,719
Other electric revenues	169	169	494	503
Other revenues	11	12	34	42
Total operating revenues	5,401	5,339	13,921	14,450
Operating Expenses:
Fuel	1,520	1,656	3,932	4,765
Purchased power	193	194	507	514
Other operations and maintenance	1,097	1,021	3,320	3,026
Depreciation and amortization	528	514	1,515	1,515
Taxes other than income taxes	264	258	761	751
Estimated loss on Kemper IGCC	150	418	182	798
Total operating expenses	3,752	4,061	10,217	11,369
Operating Income (Loss)	1,649	1,278	3,704	3,081
Other Income and (Expense):
Allowance for equity funds used during construction	60	63	163	182
Interest expense, net of amounts capitalized	(218)	(207)	(612)	(623)
Other income (expense), net	(21)	(7)	(41)	(20)
Total other income and (expense)	(179)	(151)	(490)	(461)
Earnings Before Income Taxes	1,470	1,127	3,214	2,620
Income taxes (benefit)	500	392	1,076	889
Net Income (Loss)	970	735	2,138	1,731
Dividends on preferred and preference stock of subsidiaries	11	17	42	51
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	$ 959	$ 718	$ 2,096	$ 1,680
Earnings per share (EPS) -
Basic EPS (in dollars per share)	$ 1.05	$ 0.80	$ 2.30	$ 1.88
Diluted EPS (in dollars per share)	$ 1.05	$ 0.80	$ 2.30	$ 1.87
Average number of shares of common stock outstanding (in millions)
Basic (in shares)	910	898	910	894
Diluted (in shares)	912	902	913	898
Cash dividends paid per share of common stock (in dollars per share)	$ 0.5425	$ 0.525	$ 1.610	$ 1.5575
Alabama Power [Member]
Operating Revenues:
Retail revenues	$ 1,558	$ 1,512	$ 4,151	$ 4,058
Wholesale revenues, non-affiliates	65	72	188	222
Wholesale revenues, affiliates	20	31	55	168
Other revenues	52	54	157	166
Total operating revenues	1,695	1,669	4,551	4,614
Operating Expenses:
Fuel	408	442	1,061	1,288
Purchased power, non-affiliates	56	57	142	153
Purchased power, affiliates	51	54	153	140
Other operations and maintenance	371	334	1,140	989
Depreciation and amortization	163	174	481	521
Taxes other than income taxes	91	88	275	265
Total operating expenses	1,140	1,149	3,252	3,356
Operating Income (Loss)	555	520	1,299	1,258
Other Income and (Expense):
Allowance for equity funds used during construction	14	15	43	36
Interest expense, net of amounts capitalized	(71)	(63)	(205)	(188)
Other income (expense), net	(7)	3	(24)	(5)
Total other income and (expense)	(64)	(45)	(186)	(157)
Earnings Before Income Taxes	491	475	1,113	1,101
Income taxes (benefit)	192	183	427	429
Net Income (Loss)	299	292	686	672
Dividends on preferred and preference stock of subsidiaries	4	10	21	30
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	295	282	665	642
Georgia Power [Member]
Operating Revenues:
Retail revenues	2,537	2,452	6,223	6,502
Wholesale revenues, non-affiliates	55	80	173	269
Wholesale revenues, affiliates	5	7	18	38
Other revenues	94	92	271	277
Total operating revenues	2,691	2,631	6,685	7,086
Operating Expenses:
Fuel	706	684	1,735	2,055
Purchased power, non-affiliates	90	77	227	219
Purchased power, affiliates	148	172	411	522
Other operations and maintenance	462	456	1,405	1,334
Depreciation and amortization	214	211	633	628
Taxes other than income taxes	107	111	302	320
Total operating expenses	1,727	1,711	4,713	5,078
Operating Income (Loss)	964	920	1,972	2,008
Other Income and (Expense):
Allowance for equity funds used during construction			24	29
Interest expense, net of amounts capitalized	(90)	(88)	(272)	(262)
Other income (expense), net	18	14	34	29
Total other income and (expense)	(72)	(74)	(238)	(233)
Earnings Before Income Taxes	892	846	1,734	1,775
Income taxes (benefit)	337	317	657	660
Net Income (Loss)	555	529	1,077	1,115
Dividends on preferred and preference stock of subsidiaries	4	4	13	13
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	551	525	1,064	1,102
Gulf Power [Member]
Operating Revenues:
Retail revenues	363	366	983	979
Wholesale revenues, non-affiliates	30	34	82	104
Wholesale revenues, affiliates	17	21	52	97
Other revenues	19	17	53	49
Total operating revenues	429	438	1,170	1,229
Operating Expenses:
Fuel	143	164	375	478
Purchased power, non-affiliates	26	27	76	57
Purchased power, affiliates	4	4	22	19
Other operations and maintenance	90	85	274	251
Depreciation and amortization	40	38	100	109
Taxes other than income taxes	35	31	91	84
Total operating expenses	338	349	938	998
Operating Income (Loss)	91	89	232	231
Other Income and (Expense):
Allowance for equity funds used during construction	3	3	11	8
Interest expense, net of amounts capitalized	(12)	(13)	(38)	(39)
Other income (expense), net	(1)	(1)	(3)	(2)
Total other income and (expense)	(10)	(11)	(30)	(33)
Earnings Before Income Taxes	81	78	202	198
Income taxes (benefit)	31	29	75	74
Net Income (Loss)	50	49	127	124
Dividends on preferred and preference stock of subsidiaries	2	2	7	7
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	48	47	120	117
Mississippi Power [Member]
Operating Revenues:
Retail revenues	244	228	601	647
Wholesale revenues, non-affiliates	76	83	216	255
Wholesale revenues, affiliates	18	39	63	82
Other revenues	3	5	13	13
Total operating revenues	341	355	893	997
Operating Expenses:
Fuel	130	169	359	459
Purchased power, non-affiliates	1	3	5	16
Purchased power, affiliates	1	2	6	17
Other operations and maintenance	63	67	206	192
Depreciation and amortization	38	23	95	70
Taxes other than income taxes	24	22	71	63
Estimated loss on Kemper IGCC	150	418	182	798
Total operating expenses	407	704	924	1,615
Operating Income (Loss)	(66)	(349)	(31)	(618)
Other Income and (Expense):
Allowance for equity funds used during construction	29	32	82	108
Interest expense, net of amounts capitalized	(13)	(9)	6	(34)
Other income (expense), net	(2)	(8)	(5)	(12)
Total other income and (expense)	14	15	83	62
Earnings Before Income Taxes	(52)	(334)	52	(556)
Income taxes (benefit)	(31)	(139)	(11)	(253)
Net Income (Loss)	(21)	(195)	63	(303)
Dividends on preferred and preference stock of subsidiaries	0	0	1	2
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	(21)	(195)	62	(305)
Southern Power [Member]
Operating Revenues:
Wholesale revenues, non-affiliates	295	332	776	870
Wholesale revenues, affiliates	104	103	303	243
Other revenues	2	0	7	2
Total operating revenues	401	435	1,086	1,115
Operating Expenses:
Fuel	118	178	361	421
Purchased power, non-affiliates	17	28	52	73
Purchased power, affiliates	5	13	18	58
Other operations and maintenance	62	46	184	168
Depreciation and amortization	64	60	183	163
Taxes other than income taxes	6	5	17	17
Total operating expenses	272	330	815	900
Operating Income (Loss)	129	105	271	215
Other Income and (Expense):
Interest expense, net of amounts capitalized	(18)	(23)	(62)	(67)
Other income (expense), net	1	5	1	6
Total other income and (expense)	(17)	(18)	(61)	(61)
Earnings Before Income Taxes	112	87	210	154
Income taxes (benefit)	1	22	14	22
Net Income (Loss)	111	65	196	132
Less: Net income attributable to noncontrolling interests	9	1	15	4
Net income attributable to Southern Power Company	$ 102	$ 64	$ 181	$ 128

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)			$ (7)	$ 6
Southern Company [Member]
Net Income (loss)	$ 970	$ 735	2,138	1,731
Qualifying hedges:
Changes in fair value, net of tax	(18)	0	(16)	0
Reclassification adjustment for amounts included in net income, net of tax	1	1	4	4
Pension and other post retirement benefit plans:
Reclassification adjustment for amounts included in net income, net of tax	2	1	5	2
Total other comprehensive income (loss)	(15)	2	(7)	6
Dividends on preferred and preference stock of subsidiaries	(11)	(17)	(42)	(51)
Comprehensive Income (Loss)	944	720	2,089	1,686
Alabama Power [Member]
Net Income (loss)	299	292	686	672
Qualifying hedges:
Changes in fair value, net of tax	(6)	0	(6)	0
Reclassification adjustment for amounts included in net income, net of tax	0	0	1	1
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	(6)	0	(5)	1
Dividends on preferred and preference stock of subsidiaries	(4)	(10)	(21)	(30)
Comprehensive Income (Loss)	293	292	681	673
Georgia Power [Member]
Net Income (loss)	555	529	1,077	1,115
Qualifying hedges:
Changes in fair value, net of tax	(11)	0	(10)	0
Reclassification adjustment for amounts included in net income, net of tax	1	0	2	1
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	(10)	0	(8)	1
Dividends on preferred and preference stock of subsidiaries	(4)	(4)	(13)	(13)
Comprehensive Income (Loss)	545	529	1,069	1,116
Gulf Power [Member]
Net Income (loss)	50	49	127	124
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	0	0	0	0
Dividends on preferred and preference stock of subsidiaries	(2)	(2)	(7)	(7)
Comprehensive Income (Loss)	50	49	127	124
Mississippi Power [Member]
Net Income (loss)	(21)	(195)	63	(303)
Qualifying hedges:
Reclassification adjustment for amounts included in net income, net of tax	0	0	1	0
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	0	0	1	0
Dividends on preferred and preference stock of subsidiaries	0	0	(1)	(2)
Comprehensive Income (Loss)	(21)	(195)	64	(303)
Southern Power [Member]
Net Income (loss)	111	65	196	132
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	0	0	0	0
Less: Comprehensive income attributable to noncontrolling interest/Dividends on preferred and preference stock of subsidiaries	9	1	15	4
Comprehensive Income (Loss)	$ 102	$ 64	$ 181	$ 128

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Southern Company [Member]
Changes in fair value, tax	$ (11)	$ 0	$ (10)	$ 0
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	1	1	3	2
Reclassification adjustment for amounts of pension and other post retirement benefit plans included in net income, tax	1	1	3	2
Alabama Power [Member]
Changes in fair value, tax	(4)	0	(4)	0
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	0	1	1	1
Georgia Power [Member]
Changes in fair value, tax	(7)	0	(7)	0
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	0	1	1	1
Mississippi Power [Member]
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Southern Company [Member]
Operating Activities:
Net income (loss)	$ 2,138	$ 1,731
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	1,787	1,798
Deferred income taxes	821	330
Investment tax credits	319	(70)
Allowance for equity funds used during construction	(163)	(182)
Stock based compensation expense	77	51
Estimated loss on Kemper IGCC	182	798
Income taxes receivable, non-current	(444)	0
Other, net	7	(116)
Changes in certain current assets and liabilities —
-Receivables	(118)	(640)
-Fossil fuel stock	239	522
-Materials and supplies	(22)	(45)
-Other current assets	(18)	(29)
-Accounts payable	(266)	(92)
-Accrued taxes	408	403
-Accrued compensation	(129)	96
-Mirror CWIP	99	112
-Other current liabilities	171	20
Net cash provided from operating activities	5,088	4,687
Investing Activities:
Plant acquisitions	(1,128)	(218)
Property additions	(3,490)	(3,686)
Investment in restricted cash	0	(11)
Nuclear decommissioning trust fund purchases	(1,164)	(635)
Nuclear decommissioning trust fund sales	1,159	633
Cost of removal, net of salvage	(118)	(106)
Change in construction payables	20	11
Prepaid long-term service agreement	(166)	(145)
Other investing activities	7	0
Net cash used for investing activities	(4,880)	(4,157)
Financing Activities:
Increase (decrease) in notes payable, net	662	(1,117)
Proceeds —
Long-term debt issuances	3,992	2,715
Interest-bearing refundable deposit	0	75
Common stock issuances	136	484
Short-term borrowings	280	0
Redemptions and repurchases —
Long-term debt	(2,562)	(437)
Interest-bearing refundable deposits	(275)	0
Preferred and preference stock	(412)	0
Common stock	(115)	(5)
Short-term borrowings	(255)	0
Payment of common stock dividends	(1,465)	(1,391)
Payment of dividends on preferred and preference stock of subsidiaries	(48)	(51)
Other financing activities	253	(48)
Net cash provided from (used for) financing activities	191	225
Net Change in Cash and Cash Equivalents	399	755
Cash and Cash Equivalents at Beginning of Period	710	659
Cash and Cash Equivalents at End of Period	1,109	1,414
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	590	560
Income taxes, net	(13)	263
Noncash transactions - Accrued property additions at end of period	483	415
Alabama Power [Member]
Operating Activities:
Net income (loss)	686	672
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	585	631
Deferred income taxes	85	68
Allowance for equity funds used during construction	(43)	(36)
Other, net	23	(33)
Changes in certain current assets and liabilities —
-Receivables	(160)	(139)
-Fossil fuel stock	69	106
-Materials and supplies	18	(8)
-Other current assets	(28)	(32)
-Accounts payable	(106)	(64)
-Accrued taxes	371	210
-Accrued compensation	(32)	18
-Retail fuel cost over recovery - short-term	81	2
-Other current liabilities	30	3
Net cash provided from operating activities	1,579	1,398
Investing Activities:
Property additions	(938)	(966)
Nuclear decommissioning trust fund purchases	(349)	(178)
Nuclear decommissioning trust fund sales	349	178
Cost of removal, net of salvage	(41)	(50)
Change in construction payables	(48)	39
Other investing activities	(22)	(26)
Net cash used for investing activities	(1,049)	(1,003)
Proceeds —
Senior notes issuances	975	400
Capital contributions from parent company	13	20
Pollution control revenue bond	80	0
Redemptions and repurchases —
Preferred and preference stock	(412)	0
Pollution control revenue bond	(134)	0
Senior notes	(250)	0
Payment of preferred and preference stock dividends	(27)	(30)
Payment of common stock dividends	(428)	(412)
Other financing activities	(11)	(6)
Net cash provided from (used for) financing activities	(194)	(28)
Net Change in Cash and Cash Equivalents	336	367
Cash and Cash Equivalents at Beginning of Period	273	295
Cash and Cash Equivalents at End of Period	609	662
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	192	174
Income taxes, net	47	227
Noncash transactions - Accrued property additions at end of period	88	57
Georgia Power [Member]
Operating Activities:
Net income (loss)	1,077	1,115
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	766	757
Deferred income taxes	12	121
Allowance for equity funds used during construction	(24)	(29)
Retail fuel cost over recovery — long-term	0	(44)
Deferred expenses	(45)	(35)
Pension, postretirement, and other employee benefits	40	28
Other, net	30	24
Changes in certain current assets and liabilities —
-Receivables	37	(377)
-Fossil fuel stock	141	337
-Prepaid income taxes	244	19
-Other current assets	(17)	(24)
-Accounts payable	(118)	(7)
-Accrued taxes	54	148
-Accrued compensation	(34)	20
-Retail fuel cost over recovery - short-term	0	(14)
-Other current liabilities	(3)	29
Net cash provided from operating activities	2,160	2,068
Investing Activities:
Property additions	(1,321)	(1,364)
Nuclear decommissioning trust fund purchases	(815)	(457)
Nuclear decommissioning trust fund sales	810	455
Cost of removal, net of salvage	(57)	(39)
Change in construction payables, net of joint owner portion	44	16
Prepaid long-term service agreement	(60)	(66)
Other investing activities	11	(3)
Net cash used for investing activities	(1,388)	(1,458)
Financing Activities:
Increase (decrease) in notes payable, net	(26)	(836)
Proceeds —
Capital contributions from parent company	41	39
Pollution control revenue bond	274	40
FFB loan	600	1,000
Short-term borrowings	250	0
Redemptions and repurchases —
Pollution control revenue bond	(268)	(37)
Senior notes	(525)	0
Short-term borrowings	(250)	0
Payment of preferred and preference stock dividends	(13)	(13)
Payment of common stock dividends	(776)	(715)
FFB loan issuance costs	0	(49)
Other financing activities	(18)	(6)
Net cash provided from (used for) financing activities	(711)	(577)
Net Change in Cash and Cash Equivalents	61	33
Cash and Cash Equivalents at Beginning of Period	24	30
Cash and Cash Equivalents at End of Period	85	63
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	251	235
Income taxes, net	311	309
Noncash transactions - Accrued property additions at end of period	192	220
Gulf Power [Member]
Operating Activities:
Net income (loss)	127	124
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	105	115
Deferred income taxes	58	29
Allowance for equity funds used during construction	(11)	(8)
Other, net	16	5
Changes in certain current assets and liabilities —
-Receivables	18	(46)
-Fossil fuel stock	18	44
-Prepaid income taxes	31	9
-Other current assets	1	3
-Accounts payable	(13)	10
-Accrued taxes	46	22
-Accrued compensation	(3)	5
-Over recovered regulatory clause revenues	10	7
-Other current liabilities	8	5
Net cash provided from operating activities	411	324
Investing Activities:
Property additions	(189)	(254)
Cost of removal, net of salvage	(9)	(9)
Change in construction payables	(29)	2
Other investing activities	(6)	(7)
Net cash used for investing activities	(233)	(268)
Financing Activities:
Increase (decrease) in notes payable, net	(34)	(44)
Proceeds —
Senior notes issuances	0	200
Common stock issuances	20	50
Pollution control revenue bond	13	42
Redemptions and repurchases —
Pollution control revenue bond	(13)	(29)
Senior notes	(60)	0
Payment of preferred and preference stock dividends	(7)	(7)
Payment of common stock dividends	(98)	(92)
Other financing activities	3	(1)
Net cash provided from (used for) financing activities	(176)	119
Net Change in Cash and Cash Equivalents	2	175
Cash and Cash Equivalents at Beginning of Period	39	22
Cash and Cash Equivalents at End of Period	41	197
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	27	29
Income taxes, net	(37)	36
Noncash transactions - Accrued property additions at end of period	17	35
Mississippi Power [Member]
Operating Activities:
Net income (loss)	63	(303)
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	94	78
Deferred income taxes	518	159
Investment tax credits	25	(108)
Allowance for equity funds used during construction	(82)	(108)
Regulatory assets associated with Kemper IGCC	(56)	(52)
Estimated loss on Kemper IGCC	182	798
Income taxes receivable, non-current	(544)	0
Other, net	7	10
Changes in certain current assets and liabilities —
-Receivables	7	(48)
-Fossil fuel stock	5	36
-Prepaid income taxes	(1)	(90)
-Other current assets	(8)	(4)
-Accounts payable	(32)	28
-Accrued taxes	24	(17)
-Accrued interest	(6)	24
-Accrued compensation	(8)	8
-Over recovered regulatory clause revenues	59	(18)
-Mirror CWIP	99	112
-Other current liabilities	3	0
Net cash provided from operating activities	349	505
Investing Activities:
Property additions	(626)	(986)
Investment in restricted cash	0	(11)
Change in construction payables	(31)	(40)
Distribution of restricted cash	0	9
Other investing activities	(29)	(22)
Net cash used for investing activities	(686)	(1,050)
Financing Activities:
Increase (decrease) in notes payable, net	475	0
Proceeds —
Capital contributions from parent company	153	311
Bonds — Other	0	23
Interest-bearing refundable deposit	0	75
Long-term debt issuance to parent company	0	220
Other long-term debt issuances	0	250
Short-term borrowings	30	0
Redemptions and repurchases —
Long-term debt to parent company	0	(220)
Other long-term debt	(350)	0
Payment of preferred and preference stock dividends	(1)	(1)
Return of capital	0	(165)
Other financing activities	(7)	(3)
Net cash provided from (used for) financing activities	300	490
Net Change in Cash and Cash Equivalents	(37)	(55)
Cash and Cash Equivalents at Beginning of Period	133	145
Cash and Cash Equivalents at End of Period	96	90
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	6	5
Income taxes, net	(55)	(210)
Noncash transactions - Accrued property additions at end of period	83	124
Noncash transactions - Issuance of promissory note to parent related to repayment of interest-bearing refundable deposit and accrued interest	301	0
Southern Power [Member]
Operating Activities:
Net income (loss)	196	132
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	187	166
Deferred income taxes	222	(6)
Investment tax credits	294	38
Amortization of investment tax credits	(14)	(8)
Deferred revenues	15	(2)
Accrued income taxes, non-current	100	0
Other, net	10	3
Changes in certain current assets and liabilities —
-Receivables	(28)	(63)
-Fossil fuel stock	6	(2)
-Prepaid income taxes	(116)	39
-Other current assets	(5)	(4)
-Accounts payable	1	27
-Accrued taxes	(247)	62
-Other current liabilities	(12)	(11)
Net cash provided from operating activities	609	371
Investing Activities:
Plant acquisitions	(1,128)	(218)
Property additions	(348)	(15)
Change in construction payables	88	(3)
Payments pursuant to long-term service agreements	(65)	(42)
Other investing activities	(1)	(10)
Net cash used for investing activities	(1,454)	(288)
Financing Activities:
Increase (decrease) in notes payable, net	18	20
Proceeds —
Senior notes issuances	650	0
Capital contributions from parent company	226	(4)
Other long-term debt issuances	400	10
Redemptions and repurchases —
Senior notes	(525)	0
Distributions to noncontrolling interests	(6)	0
Contributions from noncontrolling interests	274	7
Payment of common stock dividends	(98)	(98)
Other financing activities	(8)	0
Net cash provided from (used for) financing activities	931	(65)
Net Change in Cash and Cash Equivalents	86	18
Cash and Cash Equivalents at Beginning of Period	75	69
Cash and Cash Equivalents at End of Period	161	87
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	69	78
Income taxes, net	(215)	(91)
Noncash transactions - Accrued property additions at end of period	$ 120	$ 1

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Southern Company [Member]
Net cash paid for capitalized interest	$ 88	$ 80
Alabama Power [Member]
Net cash paid for capitalized interest	15	13
Georgia Power [Member]
Net cash paid for capitalized interest	10	13
Gulf Power [Member]
Net cash paid for capitalized interest	5	4
Mississippi Power [Member]
Interest paid	58	55
Net cash paid for capitalized interest	52	50
Southern Power [Member]
Net cash paid for capitalized interest	$ 4	$ 0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Deferred Charges and Other Assets:
Total Assets	$ 75,215	$ 70,923
Common Stockholders' Equity:
Total Stockholders' Equity	21,923	20,926
Southern Company [Member]
Current Assets:
Cash and cash equivalents	1,109	710
Receivables —
Customer accounts receivable	1,432	1,090
Unbilled revenues	488	432
Under recovered regulatory clause revenues	126	136
Other accounts and notes receivable	248	307
Accumulated provision for uncollectible accounts	(19)	(18)
Fossil fuel stock, at average cost	691	930
Materials and supplies, at average cost	1,046	1,039
Vacation pay	177	177
Prepaid expenses	248	665
Deferred income taxes, current	258	506
Other regulatory assets, current	421	346
Other current assets	45	50
Total current assets	6,270	6,370
Property, Plant, and Equipment:
In service	71,929	70,013
Less accumulated provision for depreciation	24,190	24,059
Plant in service, net of depreciation	47,739	45,954
Other utility plant, net	73	211
Nuclear fuel, at amortized cost	869	911
Construction work in progress	9,562	7,792
Total property, plant, and equipment	58,243	54,868
Other Property and Investments:
Nuclear decommissioning trusts, at fair value	1,473	1,546
Leveraged leases	752	743
Miscellaneous property and investments	489	203
Total other property and investments	2,714	2,492
Deferred Charges and Other Assets:
Deferred charges related to income taxes	1,553	1,510
Unamortized debt issuance expense	203	202
Unamortized loss on reacquired debt	232	243
Other regulatory assets, deferred	4,733	4,334
Income taxes receivable, non-current	444	0
Other deferred charges and assets	823	904
Total deferred charges and other assets	7,988	7,193
Total Assets	75,215	70,923
Current Liabilities:
Securities due within one year	3,313	3,333
Interest-bearing refundable deposits	0	275
Notes payable	1,490	803
Accounts payable —
Accounts payable	1,419	1,593
Customer deposits	400	390
Accrued taxes —
Accrued income taxes	404	151
Other accrued taxes	566	487
Accrued interest	223	295
Accrued vacation pay	223	223
Accrued compensation	462	576
Mirror CWIP	369	271
Other current liabilities	820	570
Total current liabilities	9,689	8,967
Long-term Debt:
Total Long-term Debt	22,326	20,841
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	11,990	11,568
Deferred credits related to income taxes	183	192
Accumulated deferred investment tax credits	1,004	1,208
Employee benefit obligations	2,408	2,432
Asset retirement obligations	2,952	2,168
Unrecognized tax benefits	369	4
Other cost of removal obligations	1,210	1,215
Other regulatory liabilities, deferred	399	398
Other deferred credits and liabilities	603	590
Total deferred credits and other liabilities	21,118	19,775
Total Liabilities	53,133	49,583
Redeemable Preferred Stock of Subsidiaries	118	375
Redeemable Noncontrolling Interest	41	39
Common Stockholders' Equity:
Common stock	4,558	4,539
Paid-in capital	6,150	5,955
Treasury, at cost	(141)	(26)
Retained earnings (accumulated deficit)	10,233	9,609
Accumulated other comprehensive income (loss)	(136)	(128)
Total common stockholders' equity	20,664	19,949
Preferred and Preference Stock of Subsidiaries	609	756
Noncontrolling Interest	650	221
Total Stockholders' Equity	21,923	20,926
Total Liabilities and Stockholders' Equity	75,215	70,923
Alabama Power [Member]
Current Assets:
Cash and cash equivalents	609	273
Receivables —
Customer accounts receivable	460	345
Unbilled revenues	134	138
Under recovered regulatory clause revenues	67	74
Other accounts and notes receivable	34	23
Affiliated companies	43	37
Accumulated provision for uncollectible accounts	(9)	(9)
Fossil fuel stock, at average cost	199	268
Materials and supplies, at average cost	398	406
Vacation pay	65	65
Prepaid expenses	79	244
Other regulatory assets, current	118	84
Other current assets	9	5
Total current assets	2,206	1,953
Property, Plant, and Equipment:
In service	23,922	23,080
Less accumulated provision for depreciation	8,623	8,522
Plant in service, net of depreciation	15,299	14,558
Nuclear fuel, at amortized cost	325	348
Construction work in progress	1,117	1,006
Total property, plant, and equipment	16,741	15,912
Other Property and Investments:
Equity investments in unconsolidated subsidiaries	69	66
Nuclear decommissioning trusts, at fair value	712	756
Miscellaneous property and investments	91	84
Total other property and investments	872	906
Deferred Charges and Other Assets:
Deferred charges related to income taxes	530	525
Deferred under recovered regulatory clause revenues	66	31
Other regulatory assets, deferred	1,055	1,063
Other deferred charges and assets	163	162
Total deferred charges and other assets	1,814	1,781
Total Assets	21,633	20,552
Current Liabilities:
Securities due within one year	600	454
Accounts payable —
Affiliated accounts payable	272	248
Other accounts payable	272	443
Customer deposits	88	87
Accrued taxes —
Accrued income taxes	105	2
Other accrued taxes	117	37
Accrued interest	67	66
Accrued vacation pay	54	54
Accrued compensation	103	131
Other current liabilities	118	82
Total current liabilities	1,796	1,604
Long-term Debt:
Total Long-term Debt	6,699	6,176
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	3,965	3,874
Deferred credits related to income taxes	70	72
Accumulated deferred investment tax credits	120	125
Employee benefit obligations	319	326
Asset retirement obligations	1,288	829
Other cost of removal obligations	742	744
Other regulatory liabilities, deferred	152	239
Deferred over recovered regulatory clause revenues	128	47
Other deferred credits and liabilities	73	79
Total deferred credits and other liabilities	6,857	6,335
Total Liabilities	15,352	14,115
Redeemable Preferred Stock	85	342
Preference Stock	196	343
Common Stockholders' Equity:
Common stock	1,222	1,222
Paid-in capital	2,328	2,304
Retained earnings (accumulated deficit)	2,483	2,255
Accumulated other comprehensive income (loss)	(33)	(29)
Total common stockholders' equity	6,000	5,752
Total Liabilities and Stockholders' Equity	21,633	20,552
Georgia Power [Member]
Current Assets:
Cash and cash equivalents	85	24
Receivables —
Customer accounts receivable	758	553
Unbilled revenues	243	201
Joint owner accounts receivable	52	121
Other accounts and notes receivable	47	61
Affiliated companies	22	18
Accumulated provision for uncollectible accounts	(7)	(6)
Fossil fuel stock, at average cost	298	439
Materials and supplies, at average cost	439	438
Vacation pay	90	91
Prepaid income taxes	24	278
Other regulatory assets, current	124	136
Other current assets	94	74
Total current assets	2,269	2,428
Property, Plant, and Equipment:
In service	31,546	31,083
Less accumulated provision for depreciation	11,046	11,222
Plant in service, net of depreciation	20,500	19,861
Other utility plant, net	10	211
Nuclear fuel, at amortized cost	544	563
Construction work in progress	4,390	4,031
Total property, plant, and equipment	25,444	24,666
Other Property and Investments:
Equity investments in unconsolidated subsidiaries	62	58
Nuclear decommissioning trusts, at fair value	761	789
Miscellaneous property and investments	38	38
Total other property and investments	861	885
Deferred Charges and Other Assets:
Deferred charges related to income taxes	678	698
Deferred under recovered regulatory clause revenues	0	197
Other regulatory assets, deferred	2,075	1,753
Other deferred charges and assets	399	403
Total deferred charges and other assets	3,152	3,051
Total Assets	31,726	31,030
Current Liabilities:
Securities due within one year	1,362	1,154
Notes payable	130	156
Accounts payable —
Affiliated accounts payable	444	451
Other accounts payable	515	555
Customer deposits	260	253
Accrued taxes —
Accrued income taxes	75	1
Other accrued taxes	311	332
Accrued interest	99	96
Accrued vacation pay	62	63
Accrued compensation	120	153
Other current liabilities	345	256
Total current liabilities	3,723	3,470
Long-term Debt:
Total Long-term Debt	8,709	8,683
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	5,493	5,507
Deferred credits related to income taxes	101	106
Accumulated deferred investment tax credits	188	196
Employee benefit obligations	893	903
Asset retirement obligations	1,332	1,223
Other deferred credits and liabilities	266	255
Total deferred credits and other liabilities	8,273	8,190
Total Liabilities	20,705	20,343
Redeemable Preferred Stock	45	45
Preference Stock	221	221
Common Stockholders' Equity:
Common stock	398	398
Paid-in capital	6,251	6,196
Retained earnings (accumulated deficit)	4,123	3,835
Accumulated other comprehensive income (loss)	(17)	(8)
Total common stockholders' equity	10,755	10,421
Total Liabilities and Stockholders' Equity	31,726	31,030
Gulf Power [Member]
Current Assets:
Cash and cash equivalents	41	39
Receivables —
Customer accounts receivable	100	73
Unbilled revenues	68	58
Under recovered regulatory clause revenues	17	57
Other accounts and notes receivable	9	8
Affiliated companies	4	10
Accumulated provision for uncollectible accounts	(2)	(2)
Fossil fuel stock, at average cost	84	101
Materials and supplies, at average cost	57	56
Prepaid expenses	13	40
Other regulatory assets, current	81	74
Other current assets	1	2
Total current assets	473	516
Property, Plant, and Equipment:
In service	4,640	4,495
Less accumulated provision for depreciation	1,273	1,296
Plant in service, net of depreciation	3,367	3,199
Other utility plant, net	64	0
Construction work in progress	407	465
Total property, plant, and equipment	3,838	3,664
Other Property and Investments:
Total other property and investments	15	15
Deferred Charges and Other Assets:
Deferred charges related to income taxes	61	56
Other regulatory assets, deferred	430	416
Other deferred charges and assets	44	41
Total deferred charges and other assets	535	513
Total Assets	4,861	4,708
Current Liabilities:
Notes payable	76	110
Accounts payable —
Affiliated accounts payable	65	87
Other accounts payable	40	56
Customer deposits	36	35
Accrued taxes —
Accrued income taxes	22	0
Other accrued taxes	33	9
Accrued interest	20	11
Accrued compensation	20	23
Deferred capacity expense, current	22	22
Liabilities from risk management activities	41	37
Other current liabilities	44	23
Total current liabilities	419	413
Long-term Debt:
Total Long-term Debt	1,310	1,370
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	870	800
Employee benefit obligations	120	121
Other cost of removal obligations	226	235
Other regulatory liabilities, deferred	49	49
Deferred capacity expense	147	163
Other deferred credits and liabilities	216	101
Total deferred credits and other liabilities	1,628	1,469
Total Liabilities	3,357	3,252
Preference Stock	147	147
Common Stockholders' Equity:
Common stock	503	483
Paid-in capital	564	560
Retained earnings (accumulated deficit)	290	267
Accumulated other comprehensive income (loss)	0	(1)
Total common stockholders' equity	1,357	1,309
Total Liabilities and Stockholders' Equity	4,861	4,708
Mississippi Power [Member]
Current Assets:
Cash and cash equivalents	96	133
Receivables —
Customer accounts receivable	51	43
Unbilled revenues	42	35
Other accounts and notes receivable	11	11
Affiliated companies	31	51
Accumulated provision for uncollectible accounts	(1)	(1)
Fossil fuel stock, at average cost	95	100
Materials and supplies, at average cost	72	62
Prepaid income taxes	183	191
Other regulatory assets, current	119	73
Other current assets	10	6
Total current assets	709	704
Property, Plant, and Equipment:
In service	4,475	4,378
Less accumulated provision for depreciation	1,215	1,173
Plant in service, net of depreciation	3,260	3,205
Construction work in progress	2,596	2,161
Total property, plant, and equipment	5,856	5,366
Other Property and Investments:
Total other property and investments	6	5
Deferred Charges and Other Assets:
Deferred charges related to income taxes	278	226
Other regulatory assets, deferred	460	385
Income taxes receivable, non-current	544	0
Other deferred charges and assets	60	71
Total deferred charges and other assets	1,342	682
Total Assets	7,913	6,757
Current Liabilities:
Securities due within one year	429	778
Interest-bearing refundable deposits	0	275
Notes payable	500	0
Accounts payable —
Affiliated accounts payable	91	86
Other accounts payable	109	178
Accrued taxes —
Accrued income taxes	288	142
Other accrued taxes	67	84
Accrued interest	15	76
Accrued compensation	18	26
Over recovered regulatory clause liabilities	60	1
Mirror CWIP	369	271
Other current liabilities	87	61
Total current liabilities	2,033	1,978
Long-term Debt:
Long-term debt, affiliated	301	0
Long-term debt, non-affiliated	1,621	1,630
Total Long-term Debt	1,922	1,630
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	674	285
Accumulated deferred investment tax credits	5	283
Employee benefit obligations	147	148
Asset retirement obligations	150	48
Unrecognized tax benefits	361	2
Other cost of removal obligations	171	166
Other regulatory liabilities, deferred	66	64
Other deferred credits and liabilities	48	36
Total deferred credits and other liabilities	1,622	1,032
Total Liabilities	5,577	4,640
Redeemable Preferred Stock	33	33
Common Stockholders' Equity:
Common stock	38	38
Paid-in capital	2,767	2,612
Retained earnings (accumulated deficit)	(496)	(559)
Accumulated other comprehensive income (loss)	(6)	(7)
Total common stockholders' equity	2,303	2,084
Total Liabilities and Stockholders' Equity	7,913	6,757
Southern Power [Member]
Current Assets:
Cash and cash equivalents	161	75
Receivables —
Customer accounts receivable	100	77
Other accounts and notes receivable	35	15
Affiliated companies	50	34
Fossil fuel stock, at average cost	16	22
Materials and supplies, at average cost	60	58
Prepaid income taxes	136	19
Deferred income taxes, current	0	306
Other current assets	19	21
Total current assets	577	627
Property, Plant, and Equipment:
In service	6,049	5,657
Less accumulated provision for depreciation	1,189	1,035
Plant in service, net of depreciation	4,860	4,622
Construction work in progress	977	11
Total property, plant, and equipment	5,837	4,633
Other Property and Investments:
Goodwill	2	2
Other intangible assets, net of amortization of $11 and $8 at September 30, 2015 and December 31, 2014, respectively	318	47
Total other property and investments	320	49
Deferred Charges and Other Assets:
Prepaid long-term service agreements	157	124
Other deferred charges and assets -- affiliated	3	5
Other deferred charges and assets	146	112
Total deferred charges and other assets	306	241
Total Assets	7,040	5,550
Current Liabilities:
Securities due within one year	400	525
Notes payable	213	195
Accounts payable —
Affiliated accounts payable	69	78
Other accounts payable	161	30
Accrued taxes —
Accrued income taxes	3	72
Accrued interest	14	30
Other current liabilities	56	17
Total current liabilities	916	947
Long-term Debt:
Total Long-term Debt	1,742	1,095
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	779	863
Accumulated deferred investment tax credits	688	601
Accrued income taxes, non-current	100	0
Deferred capacity revenues -- affiliated	39	15
Other deferred credits and liabilities — affiliated	0	1
Other deferred credits and liabilities	25	18
Total deferred credits and other liabilities	1,631	1,498
Total Liabilities	4,289	3,540
Redeemable Noncontrolling Interest	41	39
Common Stockholders' Equity:
Common stock	0	0
Paid-in capital	1,401	1,176
Retained earnings (accumulated deficit)	657	573
Accumulated other comprehensive income (loss)	3	3
Total common stockholders' equity	2,061	1,752
Noncontrolling Interest, Total	649	219
Total Stockholders' Equity	2,710	1,971
Total Liabilities and Stockholders' Equity	$ 7,040	$ 5,550

Condensed Consolidated Balance8

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Southern Company [Member]
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	912,000,000	909,000,000
Treasury shares at cost	3,300,000	700,000
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	5,442,717
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	$ 11	$ 8
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, 2015
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, 2014 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, 2015 and 2014 . 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. 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. On February 6, 2015, Gulf Power announced plans to retire its coal-fired generation at Plant Smith Units 1 and 2 ( 357 MWs) by March 31, 2016. In connection with this retirement, Gulf Power reclassified the net carrying value of these units from plant in service, net of depreciation, to other utility plant, net. Gulf Power expects to recover through its rates the remaining book value of the retired units and certain costs associated with the retirements; however, recovery will be considered by the Florida PSC in future rate proceedings . In June 2015, Georgia Power identified an error affecting the billing to a small number of large commercial and industrial customers under a rate plan allowing for variable demand-driven pricing from January 1, 2013 to June 30, 2015. In the second quarter 2015, Georgia Power recorded an out of period adjustment of approximately $75 million to decrease retail revenues, resulting in a decrease to net income of approximately $47 million . Georgia Power evaluated the effects of this error on the interim and annual periods that included the billing error, as well as the current period. Based on an analysis of qualitative and quantitative factors, Georgia Power determined the error was not material to any affected period and, therefore, an amendment of previously filed financial statements was not required. Recently Issued Accounting Standards The Financial Accounting Standards Board's (FASB) ASC 606, Revenue from Contracts with Customers , revises the accounting for revenue recognition effective for fiscal years beginning after December 15, 2017. The registrants continue to evaluate the requirements of ASC 606. The ultimate impact of the new standard has not yet been determined. On February 18, 2015, the FASB issued Accounting Standards Update (ASU) 2015-02, Amendments to the Consolidation Analysis , which makes certain changes to both the variable interest model and the voting model, including changes to the identification of variable interests, the variable interest entity characteristics for a limited partnership or similar entity, and the primary beneficiary determination. This ASU is effective for fiscal years beginning after December 15, 2015. Southern Power continues to evaluate these requirements. The ultimate impact of this ASU on Southern Power has not yet been determined. On April 7, 2015, the FASB issued ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs . The ASU requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability and is effective for fiscal years beginning after December 15, 2015. Early adoption is permitted and each registrant intends to adopt the ASU in the fourth quarter 2015. The ASU is required to be applied retrospectively to all periods presented beginning in the year of adoption. Southern Company currently reflects unamortized debt issuance costs in unamortized debt issuance expense on its balance sheet. The traditional operating companies and Southern Power currently reflect unamortized debt issuance costs in other deferred charges and assets on their balance sheets. Upon adoption, the reclassification will not have a material impact on the results of operations, financial position, or cash flows of any registrant. 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 the EPA's regulation of CCR. On April 17, 2015, the EPA published the Disposal of Coal Combustion Residuals from Electric Utilities final rule (CCR Rule) in the Federal Register, which became effective on October 19, 2015. Therefore, Alabama Power, Gulf Power, and Mississippi Power recorded new asset retirement obligations (ARO) for facilities that are subject to the CCR Rule. Georgia Power had previously recorded AROs as a result of state requirements in Georgia which closely align with the requirements of the CCR Rule. The cost estimates below are based on information as of September 30, 2015 using 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 CCR Rule requirements for closure in place. 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 operating companies expect to continue to periodically update these estimates. As of September 30, 2015 , details of the AROs, including those related to the CCR Rule, included in Southern Company's and the traditional operating companies' Condensed Balance Sheets herein were as follows: Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Balance at beginning of year $ 2,201 $ 829 $ 1,255 $ 17 $ 48 Liabilities incurred 644 402 — 101 97 Liabilities settled (19 ) (1 ) (18 ) — — Accretion 83 38 42 1 2 Cash flow revisions 214 20 193 3 25 Balance at end of period $ 3,123 $ 1,288 $ 1,472 $ 122 $ 172 The increases in liabilities incurred and cash flow revisions for the nine months ended September 30, 2015 primarily relate to an increase in AROs associated with facilities impacted by the CCR Rule. In connection with permitting activity in the third quarter 2015 related to the coal ash pond at the retired Plant Scholz facility, Gulf Power recorded additional AROs of $30 million .

Contingencies and Regulatory Ma

Contingencies and Regulatory Matters	9 Months Ended
	Sep. 30, 2015
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 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. AGL Resources Merger Litigation AGL Resources and each member of the AGL Resources board of directors have been named as defendants in four purported shareholder class action lawsuits filed in the United States District Court for the Northern District of Georgia in September and October 2015. These actions were filed on behalf of named plaintiffs and other AGL Resources shareholders challenging the Merger and seeking, among other things, preliminary and permanent injunctive relief enjoining the Merger, and, in certain circumstances, damages. Southern Company and Merger Sub were also named as defendants in two of these lawsuits. Southern Company intends to vigorously defend these suits. Southern Company does not believe these suits will impact the completion of the Merger, and they are not expected to have a material impact on Southern Company's financial statements. However, the ultimate outcome of these matters cannot be determined at this time. See Note (I) under "Southern Company – Proposed Merger with AGL Resources" herein for additional information regarding the Merger. Environmental Matters New Source Review Actions As part of a nationwide enforcement initiative against the electric utility industry which began in 1999, the EPA brought civil enforcement actions in federal district court against Alabama Power and Georgia Power alleging violations of the New Source Review (NSR) provisions of the Clean Air Act at certain coal-fired electric generating units, including units co-owned by Gulf Power and Mississippi Power. The case against Georgia Power (including claims related to a unit co-owned by Gulf Power) has been administratively closed in the U.S. District Court for the Northern District of Georgia since 2001. The case against Alabama Power (including claims involving a unit co-owned by Mississippi Power) was partially settled in 2006 through a consent decree with the EPA. On August 24, 2015, the U.S. District Court for the Northern District of Alabama entered an order approving the joint stipulation among Alabama Power, the EPA, and the U.S. Department of Justice modifying the 2006 consent decree to resolve all remaining claims in the case against Alabama Power. Under the modified consent decree, Alabama Power will, without admitting liability, operate certain units subject to emission rates and an annual emissions cap; use only natural gas at certain other units, including a unit co-owned by Mississippi Power; retire certain units at Plants Gorgas and Barry; pay a $100,000 civil penalty; and invest $1.5 million in electric transportation infrastructure projects over three years . 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 properties. The traditional operating companies have each received authority from their respective state PSCs to recover approved environmental compliance costs through regulatory mechanisms. These rates are adjusted annually or as necessary within limits approved by the state PSCs. Georgia Power's environmental remediation liability as of September 30, 2015 was $29 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. Additional response actions at this 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. Assessment and potential cleanup of other sites are anticipated. Georgia Power and numerous other entities have been designated by the EPA as PRPs at the Ward Transformer Superfund site located in Raleigh, North Carolina. In 2011, the EPA issued a Unilateral Administrative Order (UAO) to Georgia Power and 22 other parties, ordering specific remedial action of certain areas at the site. Later in 2011, Georgia Power filed a response with the EPA stating it has sufficient cause to believe it is not a liable party under CERCLA. The EPA notified Georgia Power in 2011 that it is considering enforcement options against Georgia Power and other non-complying UAO recipients. If the EPA pursues enforcement actions and the court determines that a respondent failed to comply with the UAO without sufficient cause, the EPA may also seek civil penalties of up to $37,500 per day for the violation and punitive damages of up to three times the costs incurred by the EPA as a result of the party's failure to comply with the UAO. In addition to the EPA's action at this site, Georgia Power, along with many other parties, was sued in a private action by several existing PRPs for cost recovery related to the removal action. In 2013, the U.S. District Court for the Eastern District of North Carolina Western Division ruled that Georgia Power has no liability in the private action and, on March 20, 2015, the U.S. Court of Appeals for the Fourth Circuit affirmed the lower court's ruling. Therefore, the private action is now concluded. While the EPA has not withdrawn the UAO, Georgia Power believes it is unlikely that the EPA would pursue any claims against Georgia Power for this matter given the conclusion of this private action. See Note 1 to the financial statements of Georgia Power under "Environmental Remediation Recovery" in Item 8 of the Form 10-K for additional information regarding the regulatory treatment for environmental remediation expenditures. Gulf Power's environmental remediation liability includes estimated costs of environmental remediation projects of approximately $46 million as of September 30, 2015 . 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. In 2003, Mississippi Power and numerous other entities were designated by the Texas Commission on Environmental Quality (TCEQ) as PRPs at a site that was owned by an electric transformer company that handled Mississippi Power's transformers. The TCEQ approved the final site remediation plan in 2013 and, in March 2014, the impacted utilities, including Mississippi Power, agreed to commence remediation actions on the site. Mississippi Power's environmental remediation liability was $0.3 million as of September 30, 2015 and is expected to be recovered through the ECO Plan. 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, Georgia Power, Gulf Power, and Mississippi Power does not believe that additional liabilities, if any, at these sites would be material to their respective financial statements . Nuclear Fuel Disposal Cost Litigation Acting through the DOE and pursuant to the Nuclear Waste Policy Act of 1982, the U.S. government entered into contracts with Alabama Power and Georgia Power that require the DOE to dispose of spent nuclear fuel and high level radioactive waste generated at Plants Hatch and Farley and Plant Vogtle Units 1 and 2 beginning no later than January 31, 1998. The DOE has yet to commence the performance of its contractual and statutory obligation to dispose of spent nuclear fuel. Consequently, Alabama Power and Georgia Power pursued and continue to pursue legal remedies against the U.S. government for its partial breach of contract. In December 2014, the Court of Federal Claims entered a judgment in favor of Georgia Power and Alabama Power in the second spent nuclear fuel lawsuit seeking damages for the period from January 1, 2005 through December 31, 2010. On March 19, 2015, Georgia Power recovered approximately $18 million , based on its ownership interests, and Alabama Power recovered approximately $26 million . In March 2015, Georgia Power credited the award to accounts where the original costs were charged and reduced rate base, fuel, and cost of service for the benefit of customers. Alabama Power expects its portion of the damage amounts collected to be used for the benefit of customers. In March 2014, Alabama Power and Georgia Power filed additional lawsuits against the U.S. government for the costs of continuing to store spent nuclear fuel at Plants Farley and Hatch and Plant Vogtle Units 1 and 2 for the period from January 1, 2011 through December 31, 2013. The damage period was subsequently extended to December 31, 2014. Damages will continue to accumulate until the issue is resolved or storage is provided. No amounts have been recognized in the financial statements as of September 30, 2015 for any potential recoveries from the additional lawsuits. The final outcome of these matters cannot be determined at this time; however, no material impact on Southern Company's, Alabama Power's, or Georgia Power's net income is expected. 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 Note 3 to the financial statements of Southern Company and Mississippi Power under "Integrated Coal Gasification Combined Cycle" in Item 8 of the Form 10-K and "Integrated Coal Gasification Combined Cycle" herein for information regarding Mississippi Power's construction of the Kemper IGCC. Under a 2014 settlement agreement, an adjustment to Mississippi Power's wholesale revenue requirement was allowed in the event the Kemper IGCC, or any substantial portion thereof, was placed in service before or after December 1, 2014. Therefore, Mississippi Power has recorded a regulatory asset as a result of a portion of the Kemper IGCC being placed in service prior to the projected date and is amortizing this regulatory asset over the nine months ending December 31, 2015. On May 13, 2015, the FERC accepted a settlement agreement between Mississippi Power and its wholesale customers to forgo a Municipal and Rural Associations (MRA) cost-based electric tariff increase by, among other things, increasing the accrual of AFUDC and lowering the portion of CWIP in rate base, effective April 1, 2015. The additional resulting AFUDC is estimated to be approximately $13 million annually, of which $10 million relates to the Kemper IGCC. Fuel Cost Recovery Mississippi Power has a wholesale MRA and a Market Based (MB) fuel cost recovery factor and a wholesale MRA emissions cost recovery factor. At September 30, 2015, the amount of over-recovered wholesale MRA fuel costs included in the balance sheets was $14 million compared to $0.2 million at December 31, 2014. See Note 3 to the financial statements of Mississippi Power under "Retail Regulatory Matters – Fuel Cost Recovery" in Item 8 of the Form 10-K for additional information. Market-Based Rate Authority The traditional 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 operating companies and Southern Power filed a triennial market power analysis on June 30, 2014, which included continued reliance on the energy auction as tailored mitigation. On April 27, 2015, the FERC issued an order finding that the traditional 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 operating companies and in some adjacent areas. To retain market-based rate authority, the FERC directed the traditional 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 operating companies and Southern Power filed a request for rehearing on May 27, 2015 and on June 26, 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 recovery balance of each regulatory clause follows: Regulatory Clause Balance Sheet Line Item September 30, 2015 December 31, 2014 (in millions) Rate CNP Compliance * – Under Deferred under recovered regulatory clause revenues $ — $ 2 Under recovered regulatory clause revenues, current 38 47 Rate CNP PPA – Under Deferred under recovered regulatory clause revenues 66 29 Under recovered regulatory clause revenues, current 30 27 Retail Energy Cost Recovery – Over Deferred over recovered regulatory clause revenues 128 47 Natural Disaster Reserve Other regulatory liabilities, deferred 76 84 * Formerly Known As Rate CNP Environmental Rate CNP See Note 3 to the financial statements of Southern Company under "Retail Regulatory Matters – Alabama Power – Rate CNP" and " – Non-Environmental Federal Mandated Costs Accounting Order" and of Alabama Power under "Retail Regulatory Matters – Rate CNP" and " – Non-Environmental Federal Mandated Costs Accounting Order" in Item 8 of the Form 10-K for additional information regarding Alabama Power's development of a revised cost recovery mechanism and the NPNS exception for wind PPAs. On March 3, 2015, the Alabama PSC approved a modification to Rate CNP Environmental to include compliance costs for both environmental and non-environmental mandates. The recoverable non-environmental compliance costs result from laws, regulations, and other mandates directed at the utility industry involving the security, reliability, safety, sustainability, or similar considerations impacting Alabama Power's facilities or operations. This modification to Rate CNP Environmental was effective March 20, 2015 with the revised rate now defined as Rate CNP Compliance. Alabama Power incurred $50 million of non-environmental compliance costs during the first nine months of 2015 and will be limited to recovery of $50 million for the year. Customer rates will not be impacted before January 2016; therefore, the modification will increase the under recovered position for Rate CNP Compliance during 2015. On August 14, 2015, the FASB issued ASU 2015-13, allowing the NPNS exception for physical forward transactions in nodal energy markets, consistent with the manner in which Alabama Power currently accounts for its two wind PPAs. The new accounting guidance will have no impact on Southern Company's or Alabama Power's financial statements. Environmental Accounting Order In April 2015, as part of its environmental compliance strategy, Alabama Power retired Plant Gorgas Units 6 and 7. These units represented 200 MWs of Alabama Power's approximately 12,200 MWs of generating capacity. Additionally, in April 2015, Alabama Power ceased using coal at Plant Barry Units 1 and 2 ( 250 MWs), but such units will remain available on a limited basis with natural gas as the fuel source. No later than April 2016, Alabama Power expects to cease using coal at Plant Greene County Units 1 and 2 ( 300 MWs) and begin operating those units solely on natural gas. On August 24, 2015, the U.S. District Court for the Northern District of Alabama entered an order approving the NSR joint stipulation. In accordance with the joint stipulation, Alabama Power retired Plant Barry Unit 3 ( 225 MWs) and it is no longer available for generation. See "Environmental Matters – New Source Review Actions" herein for additional information regarding the NSR actions. In accordance with an accounting order from the Alabama PSC, Alabama Power transferred the unrecovered plant asset balances to a regulatory asset at their respective retirement dates. The regulatory asset will be amortized over the remaining useful lives, as established prior to the decision for retirement, and recovered through Rate CNP. As a result, these decisions will not have a significant impact on Southern Company's or Alabama Power's financial statements. 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. In accordance with the terms of the 2013 ARP, on October 2, 2015, Georgia Power filed the following tariff adjustments with the Georgia PSC to become effective January 1, 2016 pending its approval: • increase in traditional base tariffs by approximately $49 million ; • increase in the environmental compliance cost recovery tariff by approximately $75 million ; • increase in the demand-side management tariffs by approximately $7 million ; and • increase in the municipal franchise fee tariff by approximately $13 million . The ultimate outcome of this matter cannot be determined at this time. Integrated Resource Plan See Note 3 to the financial statements of Southern Company and Georgia Power under "Retail Regulatory Matters – Georgia Power – Integrated Resource Plans" and "Retail Regulatory Matters – Integrated Resource Plans," respectively, in Item 8 of the Form 10-K for additional information. To comply with the April 16, 2015 effective date of the MATS rule, Plant Branch Units 1, 3, and 4 ( 1,266 MWs), Plant Yates Units 1 through 5 ( 579 MWs), and Plant McManus Units 1 and 2 ( 122 MWs) were retired on April 15, 2015. In addition, operations were discontinued at Plant Mitchell Unit 3 ( 155 MWs) and its decertification will be requested in connection with the triennial Integrated Resource Plan in 2016. The switch to natural gas as the primary fuel is complete at Plant Yates Units 7 and 6 and the units were returned to service on May 4, 2015 and June 27, 2015, respectively. On October 13, 2015, Plant Kraft Units 1 through 4 ( 316 MWs) were retired. 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, 2015 and December 31, 2014, Georgia Power's under recovered fuel balance totaled $41 million and $199 million , respectively. For September 30, 2015 and December 31, 2014, the balance is included in current assets and current assets and other deferred charges and assets, respectively, on Southern Company's and Georgia Power's Condensed Balance Sheets herein. On September 18, 2015, Georgia Power filed a rate request with the Georgia PSC to lower total annual billings by approximately $268 million effective January 1, 2016. The Georgia PSC is scheduled to vote on this matter on December 15, 2015. The ultimate outcome of this matter cannot be determined at this time. 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. 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, and pending litigation. In 2008, Georgia Power, acting for itself and as agent for the Vogtle Owners, entered into an agreement (Vogtle 3 and 4 Agreement) with the Contractor, pursuant to which the Contractor agreed to design, engineer, procure, construct, and test Plant Vogtle Units 3 and 4. Current anticipated in-service dates for Plant Vogtle Units 3 and 4 are the second quarter 2019 and the second quarter 2020, respectively. Under the terms of the Vogtle 3 and 4 Agreement, the Vogtle Owners agreed to pay a purchase price that is 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% . Certain payment obligations of Westinghouse and CB&I Stone & Webster, Inc. (S&W) (formerly known as Stone & Webster, Inc.) under the Vogtle 3 and 4 Agreement are guaranteed by Toshiba Corporation (Toshiba) and The Shaw Group Inc. (Shaw Group) (a subsidiary of Chicago Bridge & Iron Company, N.V. (CB&I)), respectively. 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. 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 NRC issued an Early Site Permit and Limited Work Authorization which allowed limited work to begin on Plant Vogtle Units 3 and 4. The NRC certified the Westinghouse Design Control Document, as amended (DCD), for the AP1000 nuclear reactor design, in late 2011, and issued combined construction and operating licenses (COLs) in early 2012. Receipt of the COLs allowed full construction to begin. There have been technical and procedural challenges to the construction and licensing of Plant Vogtle Units 3 and 4, at the federal and state level, and additional challenges may arise as construction proceeds. In 2012, the Vogtle Owners and the Contractor began negotiations regarding the costs associated with design changes to the DCD and the delays in the timing of approval of the DCD and issuance of the COLs, including the assertion by the Contractor that the Vogtle Owners are responsible for these costs under the terms of the Vogtle 3 and 4 Agreement. Also in 2012, Georgia Power and the other Vogtle Owners filed suit against the Contractor in the U.S. District Court for the Southern District of Georgia seeking a declaratory judgment that the Vogtle Owners are not responsible for these costs. In 2012, the Contractor also filed suit against Georgia Power and the other Vogtle Owners in the U.S. District Court for the District of Columbia alleging the Vogtle Owners are responsible for these costs. The Contractor also asserted it is entitled to extensions of the guaranteed substantial completion dates of April 2016 and April 2017 for Plant Vogtle Units 3 and 4, respectively. In May 2014, the Contractor filed an amended counterclaim to the suit pending in the U.S. District Court for the Southern District of Georgia alleging that (i) the design changes to the DCD imposed by the NRC delayed module production and the impacts to the Contractor are recoverable by the Contractor under the Vogtle 3 and 4 Agreement and (ii) the changes to the basemat rebar design required by the NRC caused additional costs and delays recoverable by the Contractor under the Vogtle 3 and 4 Agreement. On March 10, 2015, the U.S. Court of Appeals for the District of Columbia Circuit affirmed the decision of the U.S. District Court for the District of Columbia, which had dismissed the Contractor's suit, ruling that the proper venue is the U.S. District Court for the Southern District of Georgia. The case is pending in the U.S. District Court for the Southern District of Georgia (Vogtle Construction Litigation). The portion of additional costs claimed by the Contractor in its initial complaint that would be attributable to Georgia Power (based on Georgia Power's ownership interest) is approximately $425 million in 2008 dollars (approximately $591 million in 2015 dollars). The Contractor did not specify in its amended counterclaim the amounts relating to these new allegations; however, the Contractor subsequently asserted estimated minimum damages related to the amended counterclaim (based on Georgia Power's ownership interest) of approximately $113 million in 2014 dollars (approximately $118 million in 2015 dollars). In June 2015, the Contractor updated its estimated damages under the initial complaint and the amended counterclaim to an aggregate (based on Georgia Power's ownership interest) of approximately $714 million (in 2015 dollars). On October 27, 2015, Westinghouse and CB&I announced an agreement under which Westinghouse or one of its affiliates will acquire S&W from CB&I, subject to satisfaction of certain conditions to closing. In addition, on October 27, 2015, Westinghouse and the Vogtle Owners entered into a term sheet (Term Sheet) setting forth the terms of a settlement agreement to resolve disputes between the Vogtle Owners and the Contractor under the Vogtle 3 and 4 Agreement, including the Vogtle Construction Litigation. In accordance with the Term Sheet: (i) the Vogtle Owners and the Contractor will enter into mutual releases of all open claims which have been asserted, including any potential extension of such open claims, as well as future claims based on events occurring prior to the effective date of the release that potentially could have been asserted under the original terms of the Vogtle 3 and 4 Agreement, including the Vogtle Construction Litigation, which will be dismissed with prejudice; (ii) the Vogtle 3 and 4 Agreement will be amended to 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; (iii) enhanced dispute resolution procedures will be implemented; (iv) the guaranteed substantial completion dates under the Vogtle 3 and 4 Agreement will be revised to match the current estimated in-service dates of June 30, 2019 for Unit 3 and June 30, 2020 for Unit 4 (as discussed below); (v) delay liquidated damages will now 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, rather than the original guaranteed substantial completion dates under the Vogtle 3 and 4 Agreement; and (vi) Georgia Power, based on its ownership interest, will pay to the Contractor and capitalize to the project cost approximately $350 million , of which approximately $120 million has been paid previously under the dispute resolution procedures of the Vogtle 3 and 4 Agreement. In addition, the Vogtle Owners and the Contractor resolved 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 proposed settlement and in connection with Westinghouse's proposed acquisition of S&W: (i) the Vogtle Owners will terminate the parent guarantee of Shaw Group with respect to certain obligations of S&W, subject to obtaining the consent of the DOE under loan guarantee agreements relating to Plant Vogtle Units 3 and 4, while the parent guarantee of Toshiba with respect to certain obligations of Westinghouse will remain in place; (ii) Westinghouse will make provisions to engage Fluor Enterprises, Inc., a subsidiary of Fluor Corporation, as a new construction subcontractor; and (iii) the Vogtle Owners, CB&I, and Shaw Group also will enter into mutual releases of any and all claims against each other arising out of the construction of Plant Vogtle Units 3 and 4. The settlement of the pending disputes between the Vogtle Owners and the Contractor, including the Vogtle Construction Litigation, is subject to consummation of Westinghouse's proposed acquisition of S&W. If this proposed acquisition is not completed, the Vogtle Construction Litigation will continue and the Contractor may from time to time continue to assert that it is entitled to additional payments with respect to its allegations, any of which could be substantial. Georgia Power will submit the ultimate settlement agreement terms and the related amendments to the Vogtle 3 and 4 Agreement to the Georgia PSC for its review. 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 certified construction capital costs to be borne by Georgia Power increase by 5% 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 2013, the Georgia PSC approved a stipulation (2013 Stipulation) entered into

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS As of September 30, 2015 , assets and liabilities measured at fair value on a recurring basis during the period, together with the associated level of the fair value hierarchy, were as follows: Fair Value Measurements Using As of September 30, 2015: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in millions) Southern Company Assets: Energy-related derivatives $ — $ 4 $ — $ 4 Interest rate derivatives — 20 — 20 Nuclear decommissioning trusts (a) 587 869 16 1,472 Cash equivalents 747 — — 747 Other investments 9 — 1 10 Total $ 1,343 $ 893 $ 17 $ 2,253 Liabilities: Energy-related derivatives $ — $ 211 $ — $ 211 Interest rate derivatives — 36 — 36 Total $ — $ 247 $ — $ 247 Alabama Power Assets: Energy-related derivatives $ — $ 2 $ — $ 2 Nuclear decommissioning trusts (b) Domestic equity 346 72 — 418 Foreign equity 46 45 — 91 U.S. Treasury and government agency securities — 28 — 28 Corporate bonds 10 126 — 136 Mortgage and asset backed securities — 18 — 18 Other — 4 16 20 Cash equivalents 484 — — 484 Total $ 886 $ 295 $ 16 $ 1,197 Liabilities: Energy-related derivatives $ — $ 54 $ — $ 54 Interest rate derivatives — 17 — 17 Total $ — $ 71 $ — $ 71 Fair Value Measurements Using As of September 30, 2015: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in millions) Georgia Power Assets: Energy-related derivatives $ — $ 2 $ — $ 2 Interest rate derivatives — 9 — 9 Nuclear decommissioning trusts (b) (c) Domestic equity 169 1 — 170 Foreign equity — 109 — 109 U.S. Treasury and government agency securities — 112 — 112 Municipal bonds — 74 — 74 Corporate bonds — 166 — 166 Mortgage and asset backed securities — 109 — 109 Other 16 5 — 21 Cash equivalents 37 — — 37 Total $ 222 $ 587 $ — $ 809 Liabilities: Energy-related derivatives $ — $ 16 $ — $ 16 Interest rate derivatives — 19 — 19 Total $ — $ 35 $ — $ 35 Gulf Power Assets: Cash equivalents $ 18 $ — $ — $ 18 Liabilities: Energy-related derivatives — 94 — 94 Mississippi Power Assets: Cash equivalents $ 64 $ — $ — $ 64 Liabilities: Energy-related derivatives — 47 — 47 Southern Power Assets: Interest rate derivatives $ — $ 1 $ — $ 1 Cash equivalents 103 — — 103 Total $ 103 $ 1 $ — $ 104 (a) For additional detail, see the nuclear decommissioning trusts sections for Alabama Power and Georgia Power in this table. (b) Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. (c) Includes the investment securities pledged to creditors and collateral received and excludes payables related to the securities lending program. As of September 30, 2015 , approximately $69 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. Valuation Methodologies The energy-related derivatives primarily consist of 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 financial products valued using the market approach. Inputs for interest rate derivatives include LIBOR interest rates, interest rate futures contracts, and occasionally, implied volatility of interest rate options. See Note (H) herein for additional information on how these derivatives are used. 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' judgment, are also obtained when available. Investments in private equity and real estate within Alabama Power's nuclear decommissioning trusts, which are reflected as "Other" in the table above, are generally classified as Level 3, as the underlying assets typically do not have observable inputs. The fund manager values these assets using various inputs and techniques depending on the nature of the underlying investments. The fair value of partnerships is determined by aggregating the value of the underlying assets. "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, 2015 , the fair value measurements of investments calculated at net asset value per share (or its equivalent), as well as the nature and risks of those investments, were as follows: As of September 30, 2015: Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period (in millions) Southern Company Nuclear decommissioning trusts: Foreign equity funds $ 109 None Monthly 5 days Equity - commingled funds 45 None Daily Daily Debt - commingled funds 16 None Daily 5 days Other - commingled funds 5 None Daily Not applicable Other - money market funds 16 None Daily Not applicable Trust-owned life insurance 112 None Daily 15 days Cash equivalents: Money market funds 747 None Daily Not applicable Alabama Power Nuclear decommissioning trusts: Equity - commingled funds $ 45 None Daily Daily Debt - commingled funds 16 None Daily 5 days Trust-owned life insurance 112 None Daily 15 days Cash equivalents: Money market funds 484 None Daily Not applicable Georgia Power Nuclear decommissioning trusts: Foreign equity funds $ 109 None Monthly 5 days Other - commingled funds 5 None Daily Not applicable Other - money market funds 16 None Daily Not applicable Cash equivalents: Money market funds 37 None Daily Not applicable Gulf Power Cash equivalents: Money market funds $ 18 None Daily Not applicable Mississippi Power Cash equivalents: Money market funds $ 64 None Daily Not applicable Southern Power Cash equivalents: Money market funds $ 103 None Daily Not applicable The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. Alabama Power and Georgia Power have external trust funds (the Funds) to comply with the NRC's regulations. The foreign equity fund in Georgia Power's nuclear decommissioning trusts seeks to provide long-term capital appreciation. In pursuing this investment objective, the foreign equity fund primarily invests in a diversified portfolio of equity securities of foreign companies, including those in emerging markets. These equity securities may include, but are not limited to, common stocks, preferred stocks, real estate investment trusts, convertible securities, depositary receipts (including American depositary receipts, European depositary receipts, and global depositary receipts), and rights and warrants to buy common stocks. Georgia Power may withdraw all or a portion of its investment on the last business day of each month subject to a minimum withdrawal of $1 million , provided that a minimum investment of $10 million remains. If notices of withdrawal exceed 20% of the aggregate value of the foreign equity fund, then the foreign equity fund's board may refuse to permit the withdrawal of all such investments and may scale down the amounts to be withdrawn pro rata and may further determine that any withdrawal that has been postponed will have priority on the subsequent withdrawal date. The other-commingled funds and other-money market funds in Georgia Power's nuclear decommissioning trusts are invested primarily in a diversified portfolio of high-quality, short-term, liquid debt securities. The funds represent cash collateral received under the Funds' managers' securities lending program and/or excess cash held within each separate investment account. The primary objective of the funds is to provide a high level of current income consistent with stability of principal and liquidity. The funds invest primarily in, but not limited to, commercial paper, floating and variable rate demand notes, debt securities issued or guaranteed by the U.S. government or its agencies or instrumentalities, time deposits, repurchase agreements, municipal obligations, notes, and other high-quality short-term liquid debt securities that mature in 90 days or less. Redemptions are available on a same day basis up to the full amount of the investment in the fund. See Note 1 to the financial statements of Southern Company and Georgia Power under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information. Alabama Power's nuclear decommissioning trusts include investments in Trust-Owned Life Insurance (TOLI). The taxable nuclear decommissioning trusts invest in the TOLI in order to minimize the impact of taxes on the portfolios and can draw on the value of the TOLI through death proceeds, loans against the cash surrender value, and/or the cash surrender value, subject to legal restrictions. The amounts reported in the table above reflect the fair value of investments the insurer has made in relation to the TOLI agreements. The nuclear decommissioning trusts do not own the underlying investments, but the fair value of the investments approximates the cash surrender value of the TOLI policies. The investments made by the insurer are in commingled funds. These commingled funds, along with other equity and debt commingled funds held in Alabama Power's nuclear decommissioning trusts, primarily include investments in domestic and international equity securities and predominantly high-quality fixed income securities. These fixed income securities may include U.S. Treasury and government agency fixed income securities, non-U.S. government and agency fixed income securities, domestic and foreign corporate fixed income securities, and mortgage and asset backed securities. The passively managed funds seek to replicate the performance of a related index. The actively managed funds seek to exceed the performance of a related index through security analysis and selection. See Note 1 to the financial statements of Southern Company and Alabama Power under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information. Southern Company, Alabama Power, and Georgia Power continue to elect the option to fair value investment securities held in the nuclear decommissioning trust funds. For the three and nine months ended September 30, 2015 , the change in fair value of the funds, including reinvested interest and dividends and excluding the funds' expenses, decreased by $65 million and $33 million , respectively, at Southern Company. For the three and nine months ended September 30, 2015 , Alabama Power recorded a decrease in fair value of $39 million and $19 million , respectively, as a decrease in regulatory liabilities. For the three and nine months ended September 30, 2015 , Georgia Power recorded a decrease in fair value of $26 million and $14 million , respectively, as a reduction of its regulatory asset related to its ARO. The money market funds are short-term investments of excess funds in various money market mutual funds, which are portfolios of short-term debt securities. The money market funds are regulated by the SEC and typically receive the highest rating from credit rating agencies. Regulatory and rating agency requirements for money market funds include minimum credit ratings and maximum maturities for individual securities and a maximum weighted average portfolio maturity. Redemptions are available on a same day basis up to the full amount of the investment in the money market funds. As of September 30, 2015 , 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 $ 25,489 $ 26,099 Alabama Power $ 7,295 $ 7,558 Georgia Power $ 9,887 $ 10,231 Gulf Power $ 1,310 $ 1,338 Mississippi Power $ 2,273 $ 2,228 Southern Power $ 2,142 $ 2,149 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, 2015
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, 2015 Three Months Ended September 30, 2014 Nine Months Ended September 30, 2015 Nine Months Ended September 30, 2014 (in millions) As reported shares 910 898 910 894 Effect of options and performance share award units 2 4 3 4 Diluted shares 912 902 913 898 Stock options and performance share award units that were not included in the diluted earnings per share calculation because they were anti-dilutive were 15 million and 1 million for the three and nine months ended September 30, 2015 , respectively, and were 16 million and 17 million for the three and nine months ended September 30, 2014 , 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 Interest (*) (in thousands) (in millions) Balance at December 31, 2014 908,502 (725 ) $ 19,949 $ 756 $ 221 $ 20,926 Net income after dividends on preferred and preference stock — — 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 interest — — — — 429 429 Distributions to noncontrolling interest — — — — (13 ) (13 ) Net income attributable to noncontrolling interest — — — — 13 13 Other — (8 ) (8 ) 3 — (5 ) Balance at September 30, 2015 912,271 (3,332 ) $ 20,664 $ 609 $ 650 $ 21,923 Balance at December 31, 2013 892,733 (5,647 ) $ 19,008 $ 756 $ — $ 19,764 Net income after dividends on preferred and preference stock — — 1,680 — — 1,680 Other comprehensive income (loss) — — 6 — — 6 Treasury stock re-issued — 4,996 225 — — 225 Stock issued 7,781 — 332 — — 332 Stock repurchased, at cost — — (5 ) — — (5 ) Cash dividends on common stock — — (1,390 ) — — (1,390 ) Other — (51 ) 1 — — 1 Balance at September 30, 2014 900,514 (702 ) $ 19,857 $ 756 $ — $ 20,613 (*) Primarily related to Southern Power Company. Stock Repurchased On March 2, 2015, Southern Company announced a program to repurchase up to 20 million shares of Southern Company common stock to offset all or a portion of the incremental shares issued under its employee and director equity compensation plans, including through stock option exercises, until December 31, 2017. Under this program, approximately 2.6 million shares were repurchased through September 30, 2015 at a total cost of approximately $115 million . There were no repurchases during the three months ended September 30, 2015 and no further repurchases under this program are anticipated.

Financing

Financing	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
FINANCING	FINANCING Bank Credit Arrangements Bank credit arrangements provide liquidity support to the registrants' commercial paper borrowings and the traditional operating companies' variable rate pollution control revenue bonds. The amount of variable rate pollution control revenue bonds outstanding requiring liquidity support as of September 30, 2015 was approximately $1.8 billion (comprised of approximately $810 million at Alabama Power, $872 million at Georgia Power, $82 million at Gulf Power, and $40 million at Mississippi Power). In addition, at September 30, 2015 , the traditional operating companies had approximately $354 million (comprised of approximately $200 million at Alabama Power, $121 million at Georgia Power, and $33 million at Gulf Power) of fixed rate pollution control revenue bonds outstanding that were required to be reoffered within the next 12 months, of which $120 million were remarketed by Alabama Power subsequent to September 30, 2015. See Note 6 to the financial statements of each registrant under "Bank Credit Arrangements" in Item 8 of the Form 10-K for additional information. See "Financing Activities" herein for additional information. The following table outlines the committed credit arrangements by company as of September 30, 2015 : Expires Executable Term Loans Due Within One Year Company 2015 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 — 40 — 500 800 1,340 1,339 — — — 40 Georgia Power — — — — 1,750 1,750 1,732 — — — — Gulf Power 20 225 30 — — 275 275 50 — 50 195 Mississippi Power (b) 15 220 — — — 235 210 30 30 60 175 Southern Power (c) — — — — 600 600 567 — — — — Other — 70 — — — 70 70 — — — 70 Total $ 35 $ 555 $ 30 $ 1,500 $4,400 $ 6,520 $ 6,443 $ 80 $ 30 $ 110 $ 480 (a) Excludes the $8.1 billion Bridge Agreement entered into in September 2015 that will be funded only to the extent necessary to provide financing for the Merger as discussed herein. (b) Subsequent to September 30, 2015, a $15 million bank credit arrangement expired pursuant to its terms. (c) Excludes the Tranquillity Credit Agreement assumed with the acquisition of Tranquillity on August 28, 2015, which is non-recourse to Southern Power Company, the proceeds of which are being used to finance project costs related to Tranquillity's solar facility currently under construction in California. See Note (I) to the Condensed Financial Statements herein for additional information regarding Tranquillity. As reflected in the table above, in August 2015, Southern Company, Alabama Power, Georgia Power, and Southern Power Company each amended and restated their multi-year credit arrangements, which, among other things, extended the maturity dates from 2018 to 2020. Southern Company and Southern Power Company increased their borrowing ability under these arrangements to $1.25 billion from $1.0 billion and to $600 million from $500 million , respectively. Georgia Power increased its borrowing ability by $150 million under its facility maturing in 2020, and terminated its aggregate $150 million facilities maturing in 2016. In September 2015, Southern Company entered into an additional multi-year credit arrangement for $1.0 billion with a maturity date of 2018, which contains a covenant that limits debt levels to 70% of total capitalization, as defined in the agreement. Additionally, Southern Company amended its existing multi-year credit arrangement to increase the limit on debt levels to 70% from 65% of total capitalization, as defined in the agreement. Alabama Power entered into a new $500 million three -year credit arrangement which replaced a majority of Alabama Power's bi-lateral credit arrangements. 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 Company intends to initially fund the cash consideration for the Merger using approximately $7.0 billion of debt and $1.0 billion of equity. Southern Company expects to issue approximately $2.0 billion of additional equity through 2019 to offset a portion of the debt issued to fund the cash consideration for the Merger. In addition, Southern Company entered into the $8.1 billion Bridge Agreement on September 30, 2015 to provide financing for the Merger in the event long-term financing is not available. The Bridge Agreement provides for total loan commitments in an aggregate amount of $8.1 billion to fund the payment of the cash consideration payable under the Merger Agreement and other cash payments required in connection with the consummation of the Merger, the Bridge Agreement and the borrowings thereunder, the other financing transactions related to the Merger, and the payment of fees and expenses incurred in connection with the foregoing. If funded, the loan under the Bridge Agreement will mature and be payable in full on the date that is 364 days after the funding of the commitments under the Bridge Agreement (Closing Date). As of September 30, 2015, Southern Company had no outstanding loans under the Bridge Agreement. See Note (I) under "Southern Company – Proposed Merger with AGL Resources" herein for additional information regarding the Merger. Financing Activities The following table outlines the long-term debt financing activities for Southern Company and its subsidiaries for the first nine months of 2015 : Company Senior Note Issuances Senior Note Redemptions Revenue Bond Issuances and Reofferings of Purchased Bonds (a) Revenue Other Long-Term Debt Issuances Other Long-Term Debt Redemptions and Maturities (b) (in millions) Southern Company $ 600 $ 400 $ — $ — $ 400 $ — Alabama Power 975 250 80 134 — — Georgia Power — 525 274 268 600 20 Gulf Power — 60 13 13 — — Mississippi Power — — — — — 352 Southern Power 650 525 — — 400 3 Other — — — — — 13 Total $ 2,225 $ 1,760 $ 367 $ 415 $ 1,400 $ 388 (a) Includes a reoffering by Alabama Power of $80 million aggregate principal amount of revenue bonds purchased and held since April 2015; reofferings by Georgia Power of $104.6 million and $65 million aggregate principal amount of revenue bonds purchased and held since 2013 and April 2015, respectively; and a reoffering by Gulf Power of $13 million aggregate principal amount of revenue bonds purchased and held in July 2015. Also includes repurchases and reofferings by Georgia Power of $94.6 million and $10 million aggregate principal amount of revenue bonds in August 2015 in connection with optional tenders. (b) Includes reductions in capital lease obligations resulting from cash payments under capital leases. Southern Company In June 2015, Southern Company issued $600 million aggregate principal amount of Series 2015A 2.750% Senior Notes due June 15, 2020. The proceeds were used to pay a portion of Southern Company's outstanding short-term indebtedness and for other general corporate purposes. In September 2015, Southern Company entered into a $400 million aggregate principal amount 18 -month floating rate bank loan bearing interest based on one-month LIBOR. The proceeds were used for working capital and other general corporate purposes. Subsequent to September 30, 2015, Southern Company issued $1.0 billion aggregate principal amount of Series 2015A 6.25% Junior Subordinated Notes due October 15, 2075. The proceeds were used to pay a portion of Southern Company's outstanding short-term indebtedness and for other general corporate purposes. Alabama Power In March 2015, Alabama Power issued $550 million aggregate principal amount of Series 2015A 3.750% Senior Notes due March 1, 2045. The proceeds were used to redeem $250 million aggregate principal amount of Series DD 5.65% Senior Notes due March 15, 2035 and for general corporate purposes, including Alabama Power's continuous construction program . In April 2015, Alabama Power purchased and held $80 million aggregate principal amount of Industrial Development Board of the City of Mobile, Alabama Pollution Control Revenue Bonds (Alabama Power Company Barry Plant Project), Series 2007-B. Alabama Power reoffered these bonds to the public in May 2015. Also in April 2015, Alabama Power issued $175 million additional aggregate principal amount of its Series 2015A 3.750% Senior Notes due March 1, 2045 (Additional Series 2015A Senior Notes) and $250 million aggregate principal amount of its Series 2015B 2.800% Senior Notes due April 1, 2025 (Series 2015B Senior Notes). A portion of the proceeds of the Additional Series 2015A Senior Notes and the Series 2015B Senior Notes were used in May 2015 to redeem 6.48 million shares ( $162 million aggregate stated capital) of Alabama Power's 5.20% Class A Preferred Stock at a redemption price of $25 per share plus accrued and unpaid dividends to the redemption date, 4.0 million shares ( $100 million aggregate stated capital) of Alabama Power's 5.30% Class A Preferred Stock at a redemption price of $25 per share plus accrued and unpaid dividends to the redemption date, and 6.0 million shares ( $150 million aggregate stated capital) of Alabama Power's 5.625% Series Preference Stock at a redemption price of $25 per share plus accrued and unpaid dividends to the redemption date, and the remaining net proceeds were used for general corporate purposes, including Alabama Power's continuous construction program. Georgia Power In April 2015, Georgia Power purchased and held $65 million aggregate principal amount of Development Authority of Burke County (Georgia) Pollution Control Revenue Bonds (Georgia Power Company Plant Vogtle Project), Second Series 2008. Georgia Power reoffered these bonds to the public in May 2015. In May 2015, Georgia Power reoffered to the public $104.6 million aggregate principal amount of Development Authority of Burke County (Georgia) Pollution Control Revenue Bonds (Georgia Power Company Plant Vogtle Project), First Series 2013, which had been previously purchased and held since 2013. In June 2015, Georgia Power made additional borrowings under the FFB Credit Facility in an aggregate principal amount of $600 million . The interest rate applicable to the $600 million principal amount is 3.283% for an interest period that extends to 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. Georgia Power settled $350 million of interest rate swaps related to this borrowing for approximately $6 million , which will be amortized to interest expense over 10 years . In August 2015, in connection with optional tenders, Georgia Power repurchased and reoffered to the public $94.6 million aggregate principal amount of Development Authority of Bartow County (Georgia) Pollution Control Revenue Bonds (Georgia Power Company Plant Bowen Project), First Series 2009 and $10 million aggregate principal amount of Development Authority of Burke County (Georgia) Pollution Control Revenue Bonds (Georgia Power Company Plant Vogtle Project), First Series 2013. Mississippi Power In April 2015, Mississippi Power entered into two short-term floating rate bank loans with a maturity date of April 1, 2016, in an aggregate principal amount of $475 million , bearing interest based on one-month LIBOR. The proceeds of these loans were used for the repayment of term loans in an aggregate principal amount of $275 million , working capital, and other general corporate purposes, including Mississippi Power's ongoing construction program. Mississippi Power also amended three outstanding floating rate bank loans for an aggregate principal amount of $425 million which, among other things, extended the maturity dates from various dates in 2015 to April 1, 2016. In June 2015, Mississippi Power issued an 18 -month floating rate promissory note to Southern Company bearing interest based on one-month LIBOR. This note was for an aggregate principal amount of approximately $301 million , the amount paid by Southern Company to SMEPA pursuant to Southern Company's guarantee of the return of SMEPA's deposits in connection with the termination of the APA. See Note (B) under "Integrated Coal Gasification Combined Cycle – Termination of Proposed Sale of Undivided Interest to SMEPA" herein for additional information. Southern Power In May 2015, Southern Power Company issued $350 million aggregate principal amount of Series 2015A 1.500% Senior Notes due June 1, 2018 and $300 million aggregate principal amount of Series 2015B 2.375% Senior Notes due June 1, 2020. The proceeds were used to repay a portion of its outstanding short-term indebtedness, for other general corporate purposes, including Southern Power's growth strategy and continuous construction program, and for a portion of the repayment at maturity of $525 million aggregate principal amount of Southern Power Company's 4.875% Senior Notes on July 15, 2015. In August 2015, Southern Power Company entered into a $400 million aggregate principal amount 13 -month floating rate bank loan bearing interest based on one-month LIBOR. The proceeds were used for working capital and other general corporate purposes, including Southern Power's growth strategy and continuous construction program. During the nine months ended September 30, 2015, Southern Power prepaid $2.6 million of long-term debt to Turner Renewable Energy, LLC.

Retirement Benefits

Retirement Benefits	9 Months Ended
	Sep. 30, 2015
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, 2015. 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 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. Components of the net periodic benefit costs for the three and nine months ended September 30, 2015 and 2014 were as follows: Pension Plans Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) 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 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 cost $ 163 $ 36 $ 45 $ 8 $ 9 Three Months Ended September 30, 2014 Service cost $ 53 $ 12 $ 16 $ 4 $ 3 Interest cost 109 26 39 4 5 Expected return on plan assets (161 ) (42 ) (57 ) (7 ) (8 ) Amortization: Prior service costs 6 2 2 — — Net (gain)/loss 28 7 10 1 2 Net cost $ 35 $ 5 $ 10 $ 2 $ 2 Nine Months Ended September 30, 2014 Service cost $ 160 $ 36 $ 47 $ 8 $ 8 Interest cost 326 78 115 14 15 Expected return on plan assets (484 ) (126 ) (170 ) (21 ) (22 ) Amortization: Prior service costs 19 5 7 1 1 Net (gain)/loss 83 23 30 3 4 Net cost $ 104 $ 16 $ 29 $ 5 $ 6 Postretirement Benefits Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) 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 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 cost $ 48 $ 4 $ 21 $ 2 $ 3 Three Months Ended September 30, 2014 Service cost $ 5 $ 1 $ 2 $ — $ — Interest cost 19 5 9 — — Expected return on plan assets (14 ) (6 ) (6 ) — — Amortization: Prior service costs 1 1 — — — Net (gain)/loss 1 — — — — Net cost $ 12 $ 1 $ 5 $ — $ — Nine Months Ended September 30, 2014 Service cost $ 16 $ 4 $ 5 $ 1 $ 1 Interest cost 59 15 26 2 2 Expected return on plan assets (44 ) (19 ) (19 ) (1 ) (1 ) Amortization: Prior service costs 3 3 — — — Net (gain)/loss 2 — 1 — — Net cost $ 36 $ 3 $ 13 $ 2 $ 2

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Current and Deferred Income Taxes State of Georgia Tax Benefits During the second quarter 2015, an agreement was reached with the Georgia Department of Revenue that will allow Southern Company to utilize a net operating loss carryforward over a four-year period beginning in 2017. Consequently, Southern Company reversed the related valuation allowance and recognized approximately $24 million in net tax benefits. See Note 5 to the financial statements of Southern Company under "Current and Deferred Income Taxes" in Item 8 of the Form 10-K for additional information. Southern Power ITC Carryforwards Southern Power had federal ITC carryforwards which are expected to result in $212 million of federal income tax benefits as of September 30, 2015 , compared to $305 million as of December 31, 2014. The carryforwards as of September 30, 2015 expire between 2031 and 2035 and are expected to be utilized by the end of 2016. Effective Tax Rate See Note 5 to the financial statements of each registrant in Item 8 of the Form 10-K for additional tax information. Mississippi Power Mississippi Power's effective tax rate was (20.9)% for the nine months ended September 30, 2015 compared to (45.5)% for the corresponding period in 2014 . The increase was primarily due to a reduction in tax benefits related to the estimated probable losses on construction of the Kemper IGCC, and a decrease in non-taxable AFUDC equity related to placing the Kemper IGCC combined cycle in service in August 2014. Southern Power Southern Power's effective tax rate was 6.9% for the nine months ended September 30, 2015 compared to 14.4% for the corresponding period in 2014. The decrease was primarily due to increased federal income tax benefits related to ITCs in 2015, partially offset by higher pre-tax earnings in 2015 and beneficial state income tax changes in 2014. 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 2015 for unrecognized tax benefits were as follows: Mississippi Power Southern Power Southern Company (in millions) Unrecognized tax benefits as of December 31, 2014 $ 165 $ 5 $ 170 Tax positions from current periods 24 7 31 Tax positions from prior periods 459 (6 ) 456 Reductions due to settlements — — — Balance as of September 30, 2015 $ 648 $ 6 $ 657 The tax positions from prior periods relate primarily to 2008 through 2013 amended federal income tax returns that were filed to include deductions for Kemper IGCC-related R&E expenditures and deferred federal investment tax credits that no longer meet the more-likely-than-not recognition threshold. See "Section 174 Research and Experimental Deduction" and "Investment Tax Credits" herein for additional information. The impact on the effective tax rate, if recognized, was as follows: As of September 30, 2015 As of December 31, 2014 Mississippi Power Southern Power Southern Company Southern Company (in millions) Tax positions impacting the effective tax rate $ (2 ) $ 6 $ 7 $ 10 Tax positions not impacting the effective tax rate 650 — 650 160 Balance of unrecognized tax benefits $ 648 $ 6 $ 657 $ 170 The tax positions impacting the effective tax rate primarily relate to federal income tax benefits related to ITCs. The tax positions not impacting the effective tax rate relate to deductions for Kemper IGCC-related R&E expenditures and deferred federal investment tax credits that no longer meet the more-likely-than-not recognition threshold. See "Section 174 Research and Experimental Deduction" and "Investment Tax Credits" herein for additional information. These amounts are presented on a gross basis without considering the related federal or state income tax impact. Section 174 Research and Experimental Deduction Southern Company reduced tax payments for 2015, and included in its 2013 and 2014 consolidated federal income tax returns deductions for R&E expenditures related to the Kemper IGCC. In May 2015, Southern Company amended its 2008 through 2013 federal income tax returns to include deductions for Kemper IGCC-related R&E expenditures. 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. The IRS is currently reviewing the underlying support for the deduction, but has not completed its audit of these expenditures. 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 $414 million and associated interest of $7 million as of September 30, 2015 . The ultimate outcome of this matter cannot be determined at this time. Investment Tax Credits The IRS allocated $279 million (Phase II) of Internal Revenue Code Section 48A tax credits to Mississippi Power in connection with the Kemper IGCC. These tax credits are dependent upon meeting the IRS certification requirements, including an in-service date no later than April 19, 2016 and the capture and sequestration (via enhanced oil recovery) of at least 65% of the CO 2 produced by the Kemper IGCC during operations in accordance with the Internal Revenue Code. Through September 30, 2015, Southern Company and Mississippi Power had recorded tax benefits totaling $276 million for the Phase II credits, of which approximately $235 million had been utilized. While the in-service date for the remainder of the Kemper IGCC is currently expected to occur in the first half of 2016, Mississippi Power now anticipates the in-service date to occur subsequent to April 19, 2016, but has not made a final determination to that effect. As of September 30, 2015, the more-likely-than-not threshold had no longer been met for recognition of these benefits; therefore, Southern Company and Mississippi Power have reflected these tax credits as unrecognized tax benefits and reclassified the Phase II credits to a current liability on their September 30, 2015 balance sheets, with no impact to net income. Repayment to the IRS would occur with the quarterly estimated tax payment following a final determination that the in-service date would occur subsequent to April 19, 2016. The ultimate outcome of this matter cannot be determined at this time.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES	DERIVATIVES Southern Company, the traditional operating companies, and Southern Power are exposed to market risks, primarily commodity price risk and interest rate 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 gross basis. See Note (C) herein 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. Energy-Related Derivatives The traditional operating companies and Southern Power enter into energy-related derivatives to hedge exposures to electricity, gas, and other fuel price changes. However, due to cost-based rate regulations and other various cost recovery mechanisms, the traditional operating companies have limited exposure to market volatility in commodity fuel prices and prices of electricity. Each of the traditional operating companies manages fuel-hedging programs, implemented per the guidelines of their respective state PSCs, through the use of financial derivative contracts, which is expected to continue to mitigate price volatility. The traditional operating companies (with respect to wholesale generating capacity) and Southern Power have limited exposure to market volatility in commodity fuel prices and prices of electricity because their long-term sales contracts shift substantially all fuel cost responsibility to the purchaser. However, the traditional operating companies and Southern Power may be exposed to market volatility in energy-related commodity prices to the extent any uncontracted wholesale generating capacity is used to sell electricity. To mitigate residual risks relative to movements in electricity prices, the traditional operating companies and Southern Power may enter into physical fixed-price contracts for the purchase and sale of electricity through the wholesale electricity market. To mitigate residual risks relative to movements in gas prices, the traditional operating companies and Southern Power may enter into fixed-price contracts for natural gas purchases; however, a significant portion of contracts are priced at market. 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 operating companies' 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 and 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 industry. 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, 2015 , 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 221 2020 2017 Alabama Power 50 2018 Georgia Power 50 2017 Gulf Power 83 2020 Mississippi Power 37 2018 Southern Power 1 2016 2017 In addition to the volumes discussed in the above table, the traditional 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, 4 million mmBtu for Georgia Power, and 1 million mmBtu for Southern 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, 2016 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, 2015 , the following interest rate derivatives were outstanding: Notional Amount Interest Rate Received Weighted Average Interest Rate Paid Hedge Maturity Date Fair Value 2015 (in millions) (in millions) Cash Flow Hedges of Forecasted Debt Alabama Power $ 200 3-month 2.93% October 2025 $ (17 ) Georgia Power 350 3-month 2.57% November 2025 (18 ) Cash Flow Hedges of Existing Debt Georgia Power 250 3-month 0.75% March 2016 — Georgia Power 200 3-month 1.01% August 2016 — Fair Value Hedges on Existing Debt Southern Company 250 1.30% 3-month August 2017 2 Southern Company 300 2.75% 3-month June 2020 8 Georgia Power 250 5.40% 3-month June 2018 3 Georgia Power 200 4.25% 3-month December 2019 5 Derivatives not Designated as Hedges Southern Power (a) 65 (b) 3-month 2.50% October 2016 (c) 1 Total $ 2,065 $ (16 ) (a) Swaption at RE Tranquillity LLC, a subsidiary of Tranquillity. See Note (I) to the Condensed Financial Statements herein for additional information regarding Tranquillity. (b) Amortizing notional amount. (c) Represents the mandatory settlement date. Settlement will be based on a 15 -year amortizing swap. The estimated pre-tax gains (losses) that will be reclassified from accumulated OCI to interest expense for the next 12-month period ending September 30, 2016 are immaterial for all registrants. Southern Company and certain subsidiaries have deferred gains and losses that are expected to be amortized into earnings through 2037. Derivative Financial Statement Presentation and Amounts At September 30, 2015 , the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at September 30, 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: Other current assets $ 3 $ 1 $ 2 $ — $ — Other deferred charges and assets 1 1 — — — Total derivatives designated as hedging instruments for regulatory purposes $ 4 $ 2 $ 2 $ — $ — N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets $ 11 $ — $ 5 $ — $ — $ — Other deferred charges and assets 8 — 4 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 19 $ — $ 9 $ — $ — $ — Derivatives not designated as hedging instruments Interest rate derivatives: Other deferred charges and assets $ 1 $ — $ — $ — $ — $ 1 Total asset derivatives $ 24 $ 2 $ 11 $ — $ — $ 1 Liability Derivatives at September 30, 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: Other current liabilities (*) $ 117 $ 36 $ 14 $ 41 $ 26 Other deferred credits and liabilities 94 18 2 53 21 Total derivatives designated as hedging instruments for regulatory purposes $ 211 $ 54 $ 16 $ 94 $ 47 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current liabilities (*) $ 36 $ 17 $ 19 $ — $ — $ — Total liability derivatives $ 247 $ 71 $ 35 $ 94 $ 47 $ — (*) Gulf Power includes current liabilities related to derivatives designated as hedging instruments in "Liabilities from risk management activities." At December 31, 2014 , the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at December 31, 2014 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: Other current assets $ 7 $ 1 $ 6 $ — $ — Other deferred charges and assets — — 1 — — Total derivatives designated as hedging instruments for regulatory purposes $ 7 $ 1 $ 7 $ — $ — N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets $ 7 $ — $ 5 $ — $ — $ — Other deferred charges and assets 1 — 1 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 8 $ — $ 6 $ — $ — $ — Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets $ 6 $ — $ — $ — $ — $ 5 Total asset derivatives $ 21 $ 1 $ 13 $ — $ — $ 5 Liability Derivatives at December 31, 2014 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: Other current liabilities (*) $ 118 $ 32 $ 23 $ 37 $ 26 Other deferred credits and liabilities 79 21 4 35 19 Total derivatives designated as hedging instruments for regulatory purposes $ 197 $ 53 $ 27 $ 72 $ 45 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current liabilities (*) $ 17 $ 8 $ 9 $ — $ — $ — Other deferred credits and liabilities 7 — 5 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 24 $ 8 $ 14 $ — $ — $ — Derivatives not designated as hedging instruments Energy-related derivatives: Other current liabilities $ 4 $ — $ — $ — $ — $ 4 Total liability derivatives $ 225 $ 61 $ 41 $ 72 $ 45 $ 4 (*) Gulf Power includes current liabilities related to derivatives designated as hedging instruments in "Liabilities from risk management activities." The derivative contracts of Southern Company, the traditional operating companies, and Southern Power are not subject to master netting arrangements or similar agreements and 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 September 30, 2015 and December 31, 2014 are presented in the following tables. Derivative Contracts at September 30, 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) $ 4 $ 2 $ 2 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (4 ) (2 ) (2 ) — — — Net energy-related derivative assets $ — $ — $ — $ — $ — $ — Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 20 $ — $ 9 $ — $ — $ 1 Gross amounts not offset in the Balance Sheet (b) (9 ) — (2 ) — — — Net interest rate derivative assets $ 11 $ — $ 7 $ — $ — $ 1 Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 211 $ 54 $ 16 $ 94 $ 47 $ — Gross amounts not offset in the Balance Sheet (b) (4 ) (2 ) (2 ) — — — Net energy-related derivative liabilities $ 207 $ 52 $ 14 $ 94 $ 47 $ — Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 36 $ 17 $ 19 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (9 ) — (2 ) — — — Net interest rate derivative liabilities $ 27 $ 17 $ 17 $ — $ — $ — (a) None of the registrants offsets fair value amounts for multiple derivative instruments executed with the same counterparty on the balance sheets; therefore, gross and net amounts of derivative assets and liabilities presented on the balance sheets are the same. (b) Includes gross amounts subject to netting terms that are not offset on the balance sheets and any cash/financial collateral pledged or received. Derivative Contracts at December 31, 2014 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) $ 13 $ 1 $ 7 $ — $ — $ 5 Gross amounts not offset in the Balance Sheet (b) (9 ) — (7 ) — — — Net energy-related derivative assets $ 4 $ 1 $ — $ — $ — $ 5 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 8 $ — $ 6 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (8 ) — (6 ) — — — Net interest rate derivative assets $ — $ — $ — $ — $ — $ — Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 201 $ 53 $ 27 $ 72 $ 45 $ 4 Gross amounts not offset in the Balance Sheet (b) (9 ) — (7 ) — — — Net energy-related derivative liabilities $ 192 $ 53 $ 20 $ 72 $ 45 $ 4 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 24 $ 8 $ 14 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (8 ) — (6 ) — — — Net interest rate derivative liabilities $ 16 $ 8 $ 8 $ — $ — $ — (a) None of the registrants offsets fair value amounts for multiple derivative instruments executed with the same counterparty on the balance sheets; therefore, gross and net amounts of derivative assets and liabilities presented on the balance sheets are the same. (b) Includes gross amounts subject to netting terms that are not offset on the balance sheets and any cash/financial collateral pledged or received. At September 30, 2015 and December 31, 2014 , 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 on the Balance Sheet at September 30, 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 $ (117 ) $ (36 ) $ (14 ) $ (41 ) $ (26 ) Other regulatory assets, deferred (94 ) (18 ) (2 ) (53 ) (21 ) Other regulatory liabilities, current (a) 3 1 2 — — Other regulatory liabilities, deferred (b) 1 1 — — — Total energy-related derivative gains (losses) $ (207 ) $ (52 ) $ (14 ) $ (94 ) $ (47 ) (a) Southern Company, Alabama Power, and Georgia Power include 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 on the Balance Sheet at December 31, 2014 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 $ (118 ) $ (32 ) $ (23 ) $ (37 ) $ (26 ) Other regulatory assets, deferred (79 ) (21 ) (4 ) (35 ) (19 ) Other regulatory liabilities, current (a) 7 1 6 — — Other regulatory liabilities, deferred (b) — — 1 — — Total energy-related derivative gains (losses) $ (190 ) $ (52 ) $ (20 ) $ (72 ) $ (45 ) (a) Southern Company, Alabama Power, and Georgia Power include other regulatory liabilities, current in other current liabilities. (b) Georgia Power includes other regulatory liabilities, deferred in other deferred credits and liabilities. For the three months ended September 30, 2015 and 2014 , the pre-tax effects of interest rate 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 2015 2014 2015 2014 (in millions) (in millions) Southern Company Interest rate derivatives $ (28 ) $ (1 ) Interest expense, net of amounts capitalized $ (2 ) $ (2 ) Alabama Power Interest rate derivatives $ (10 ) $ (1 ) Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Georgia Power Interest rate derivatives $ (18 ) $ — Interest expense, net of amounts capitalized $ (1 ) $ (1 ) For the nine months ended September 30, 2015 and 2014 , the pre-tax effects of interest rate 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 2015 2014 2015 2014 (in millions) (in millions) Southern Company Interest rate derivatives $ (26 ) $ (1 ) Interest expense, net of amounts capitalized $ (7 ) $ (6 ) Alabama Power Interest rate derivatives $ (9 ) $ (1 ) Interest expense, net of amounts capitalized $ (2 ) $ (2 ) Georgia Power Interest rate derivatives $ (17 ) $ — Interest expense, net of amounts capitalized $ (3 ) $ (2 ) Mississippi Power Interest rate derivatives $ — $ — Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Southern Power Interest rate derivatives $ — $ — Interest expense, net of amounts capitalized $ (1 ) $ (1 ) For the three and nine months ended September 30, 2015 and 2014 , the pre-tax effects of energy-related derivatives designated as cash flow hedging instruments recognized in OCI and those reclassified from accumulated OCI into earnings were immaterial for all registrants. For the three months ended September 30, 2015 and 2014 , 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) Derivative Category Statements of Income Location 2015 2014 (in millions) Southern Company Interest rate derivatives: Interest expense, net of amounts capitalized $ 15 $ (1 ) Georgia Power Interest rate derivatives: Interest expense, net of amounts capitalized $ 7 $ — For the nine months ended September 30, 2015 and 2014 , 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) Derivative Category Statements of Income Location 2015 2014 (in millions) Southern Company Interest rate derivatives: Interest expense, net of amounts capitalized $ 19 $ (4 ) Georgia Power Interest rate derivatives: Interest expense, net of amounts capitalized $ 9 $ — For the three and nine months ended September 30, 2015 and 2014, 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, 2015 and 2014 , the pre-tax effects of energy-related derivatives and interest rate derivatives not designated as hedging instruments were immaterial for all registrants. Contingent Features The registrants 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, 2015 , the registrants' collateral posted with their derivative counterparties was immaterial. At September 30, 2015 , the fair value of derivative liabilities with contingent features was $54 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 $54 million and include certain agreements that could require collateral in the event that one or more Southern Company power pool participants 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 operating companies, and Southern Power are exposed to losses related to financial instruments in the event of counterparties' nonperformance. Southern Company, the traditional operating companies, and Southern Power 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 operating companies, and Southern Power 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 operating companies', and Southern Power's exposure to counterparty credit risk. Therefore, Southern Company, the traditional 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, 2015
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS Southern Company Proposed Merger with AGL Resources On August 23, 2015, Southern Company, AGL Resources, and Merger Sub entered into the Merger Agreement. Under the terms of the Merger Agreement, subject to the satisfaction or waiver (if permissible under applicable law) of specified conditions, Merger Sub will be merged with and into AGL Resources. AGL Resources will survive the Merger and become a wholly-owned direct subsidiary of Southern Company. Upon the consummation of the Merger, each share of common stock of AGL Resources issued and outstanding immediately prior to the effective time of the Merger (Effective Time), other than shares owned by AGL Resources as treasury stock, shares owned by a subsidiary of AGL Resources, and shares owned by shareholders who have properly exercised and perfected dissenters' rights, will be converted into the right to receive $66 in cash, without interest and less any applicable withholding taxes. Other equity-based securities of AGL Resources will be cancelled for cash consideration or converted into new awards from Southern Company as described in the Merger Agreement. In accordance with GAAP, the Merger will be accounted for using the acquisition method of accounting whereby the assets acquired and liabilities assumed are recognized at fair value as of the acquisition date. The excess of the purchase price over the fair values of AGL Resources' assets and liabilities will be recorded as goodwill. Southern Company expects total cash of $8.2 billion to be required to fund the purchase price of approximately $8.0 billion to acquire AGL Resources common stock, options to purchase shares of AGL Resources common stock, and restricted stock units payable in shares of AGL Resources common stock and to fund acquisition-related expenses and financing costs of approximately $200 million . Southern Company will also assume AGL Resources' outstanding indebtedness. Consummation of the Merger is subject to the satisfaction or waiver of certain closing conditions, including, among others, (i) approval of the Merger Agreement by AGL Resources' shareholders, which is scheduled for vote on November 19, 2015, (ii) the expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, (iii) the approval of the California Public Utilities Commission, Georgia PSC, Illinois Commerce Commission, Maryland PSC, New Jersey Board of Public Utilities, and Virginia State Corporation Commission, and other approvals required under applicable state laws, and the approval of the Federal Communications Commission (FCC) for the transfer of control over the FCC licenses of certain subsidiaries of AGL Resources and any other approval which Southern Company and AGL Resources agree are required, (iv) the absence of a judgment, order, decision, injunction, ruling, or other finding or agency requirement of a governmental entity prohibiting the consummation of the Merger, and (v) other customary closing conditions, including (a) subject to certain materiality qualifiers, the accuracy of each party's representations and warranties and (b) each party's performance in all material respects of its obligations under the Merger Agreement. Southern Company expects to complete the required state regulatory filings in the fourth quarter 2015. Subject to certain limitations, either party may terminate the Merger Agreement if the Merger is not consummated by August 23, 2016, which date may be extended by either party to February 23, 2017 if, on August 23, 2016, all conditions to closing other than those relating to (i) regulatory approvals and (ii) the absence of legal restraints preventing consummation of the Merger (to the extent relating to regulatory approvals) have been satisfied. Upon termination of the Merger Agreement under certain specified circumstances, AGL Resources will be required to pay Southern Company a termination fee of $201 million or reimburse Southern Company's expenses up to $5 million (which reimbursement shall reduce on a dollar-for-dollar basis any termination fee subsequently payable by AGL Resources). Southern Company currently expects to complete the transaction in the second half of 2016. The ultimate outcome of these matters cannot be determined at this time. Merger Financing Southern Company intends to initially fund the cash consideration for the Merger using approximately $7.0 billion of debt and $1.0 billion of equity. Southern Company expects to issue approximately $2.0 billion of additional equity through 2019 to offset a portion of the debt issued to fund the cash consideration for the Merger. In addition, Southern Company entered into the $8.1 billion Bridge Agreement on September 30, 2015 to provide financing for the Merger in the event long-term financing is not available. See Note (E) under "Bank Credit Arrangements" herein for additional information regarding the Bridge Agreement. Southern Power See Note 2 to the financial statements of Southern Power under "2014 – SG2 Imperial Valley, LLC" in Item 8 of the Form 10-K for additional information. During the second quarter 2015, the fair values of the assets acquired of SG2 Imperial Valley, LLC were finalized and recorded as follows: $707 million as property, plant, and equipment and $20 million as prepayments related to transmission services. During 2015, Southern Power Company acquired or contracted to acquire through its wholly-owned subsidiaries, Southern Renewable Partnerships, LLC or Southern Renewable Energy, Inc. (SRE), the following projects in accordance with its overall growth strategy, which are included in its capital program estimates for 2015. Acquisition-related costs were expensed as incurred and were not material. The acquisitions do not include any contingent consideration unless specifically noted. Project Entity Seller; Acquisition Date Approx. Nameplate Capacity Location Southern Power Percentage Ownership Expected/Actual Commercial Operation Date PPA PPA Contract Period Approx. Purchase Price (MW) (in millions) WIND Kay Wind, LLC Apex Clean Energy Holdings, LLC 299 Kay County, Oklahoma 100 % Fourth quarter 2015 Westar Energy, Inc. and Grant River Dam Authority 20 years $ 492 (a) Grant Wind, LLC Apex Clean Energy Holdings, LLC 151 Grant County, Oklahoma 100 % First quarter 2016 Western Farmers, East Texas, and Northeast Texas Electric Cooperative 20 years $ 264 (a) SOLAR Lost Hills Blackwell Holdings, LLC (Lost Hills Blackwell) First Solar, Inc. (First Solar) 35 Kern County, California 51 % (b) April 17, 2015 City of Roseville, California/Pacific Gas and Electric Company 29 years $ 74 (c) NS Solar Holdings, LLC (North Star) First Solar 61 Fresno County, California 51 % (b) June 20, 2015 Pacific Gas and Electric Company 20 years $ 211 (d) Tranquillity Recurrent Energy, LLC 204 Fresno County, California 51 % (b) Fourth quarter 2016 Shell Energy North America (US), LP/Southern California Edison Company 18 years $ 100 (e) Desert Stateline Holdings, LLC (Desert Stateline) First Solar 300 San Bernardino County, California 51 % (b) 8 Phases from December 2015 to Third quarter 2016 Southern California Edison Company 20 years $ 439 (f) GASNA 31P, LLC (Morelos) Solar Frontier Americas Holding, LLC 15 Kern County, California 90 % Fourth quarter 2015 Pacific Gas and Electric Company 20 years $ 45 (g) (a) On February 24, 2015 and September 4, 2015, Southern Power entered into agreements to acquire Kay Wind, LLC and Grant Wind, LLC, respectively. The completion of each acquisition is subject to the seller achieving certain construction and project milestones, as well as various other customary conditions to closing. Each acquisition is expected to close at or near the expected commercial operation date. In addition, the final purchase price may be adjusted based on performance testing as specified in the applicable purchase agreement. The Grant Wind, LLC purchase price includes contingent consideration. The ultimate outcome of this matter cannot be determined at this time. (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 respective project. In addition, Southern Power is entitled to substantially all of the federal tax benefits with respect to the respective transaction. (c) Concurrently, a wholly-owned subsidiary of First Solar acquired 100% of the class B membership interests for approximately $33 million . The fair values of the assets acquired through the business combination were recorded as follows: $98 million as property, plant, and equipment and $9 million as a receivable related to transmission interconnection costs; however, the allocation of the purchase price to individual assets has not been finalized. (d) Concurrently, a wholly-owned subsidiary of First Solar acquired 100% of the class B membership interests for approximately $100 million . The fair values of the assets acquired through the business combination were recorded as follows: $266 million as property, plant, and equipment, $24 million as an intangible asset, and $21 million as a receivable related to transmission interconnection costs; however, the allocation of the purchase price to individual assets has not been finalized. (e) Concurrently, a wholly-owned subsidiary of Recurrent Energy, LLC converted all its membership interests to 100% of the class B membership interests of Tranquillity after contributing approximately $157 million of assets and receiving an initial distribution of $100 million . The fair values of the assets acquired were recorded as follows: $170 million as CWIP, $24 million as other receivables, and $37 million as payables; however, the allocation of the purchase price to individual assets has not been finalized. Subsequent to the acquisition, Southern Power and Recurrent Energy, LLC are expected to make additional construction payments of approximately $215 million and $106 million , respectively. The ultimate outcome of this matter cannot be determined at this time. (f) Concurrently, a wholly-owned subsidiary of First Solar acquired 100% of the class B membership interests for approximately $223 million . As of September 30, 2015, the fair values of the assets acquired, which includes Southern Power's and First Solar's initial payments due under the related construction agreement, were recorded as follows: $413 million as CWIP and $249 million as an intangible asset; however, the allocation of the purchase price to individual assets has 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 $6.2 million in 2016, $12.5 million per year for 2017 through 2020, and $192.8 million thereafter. Southern Power's and First Solar's remaining combined future payments, including construction payments, are estimated to be between $827 million to $844 million . The ultimate outcome of this matter cannot be determined at this time. (g) On October 22, 2015, SRE and Turner Renewable Energy, LLC (TRE), through Southern Turner Renewable Energy, LLC, a jointly-owned subsidiary owned 90% by SRE, acquired all of the outstanding membership interests of Morelos. The total purchase price, including TRE's 10% ownership, is approximately $50 million . Construction Projects In December 2014, Southern Power Company announced plans to build a solar photovoltaic facility, and during 2015, Southern Power Company acquired all the outstanding membership interests of five separate solar project development entities. The construction projects are in accordance with Southern Power's overall growth strategy and included in its capital program estimates for 2015. The total cost of construction incurred for these projects through September 30, 2015 was $299 million . The ultimate outcome of these matters cannot be determined at this time. Southern Power Company's construction projects, excluding the Tranquillity and Desert Stateline construction projects discussed above, are detailed in the table below: Solar Project Seller Approx. Nameplate Capacity County Location in Georgia Expected Commercial Operation Date PPA Counterparties PPA Contract Period Estimated Construction Cost (MW) (in millions) Taylor County N/A 146 Taylor Fourth quarter 2016 Cobb, Flint, and Sawnee Electric Membership Corporations 25 years $ 260 - $280 Decatur Parkway TradeWind Energy, Inc. 84 Decatur December 2015 Georgia Power (a) 25 years $ 170 - $173 (c) Decatur County TradeWind Energy, Inc. 20 Decatur December 2015 Georgia Power (b) 20 years $ 45 - $47 (c) Butler CERSM, LLC and Community Energy, Inc. 103 Taylor December 2016 Georgia Power (b) 30 years $ 220 - $230 (c) Pawpaw Longview Solar, LLC 30 Taylor December 2015 Georgia Power (a) 30 years $ 70 - $80 (c) Butler Solar Farm Strata Solar Development, LLC 20 Taylor December 2015 Georgia Power (b) 20 years $ 42 - $48 (c) (a) Approved by the FERC subsequent to September 30, 2015. (b) Subject to FERC approval. (c) Includes the acquisition price of all outstanding membership interests.

Segment and Related Information

Segment and Related Information	9 Months Ended
	Sep. 30, 2015
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 operating companies and Southern Power. The four traditional 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 generation assets, including renewable energy projects, and sells electricity at market-based rates in the wholesale market. Southern Company's reportable business segments are the sale of electricity by the four traditional operating companies and Southern Power. Revenues from sales by Southern Power to the traditional operating companies were $104 million and $303 million for the three and nine months ended September 30, 2015 , respectively, and $103 million and $243 million for the three and nine months ended September 30, 2014 , respectively. The "All Other" column includes parent Southern Company, which does not allocate operating expenses to business segments. Also, this category includes segments below the quantitative threshold for separate disclosure. These segments include 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, 2015 and 2014 was as follows: Electric Utilities Traditional Operating Companies Southern Power Eliminations Total All Other Eliminations Consolidated (in millions) Three Months Ended September 30, 2015: 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 September 30, 2015: 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 September 30, 2015 $ 67,750 $ 7,040 $ (404 ) $ 74,386 $ 1,480 $ (651 ) $ 75,215 Three Months Ended September 30, 2014: Operating revenues $ 5,007 $ 435 $ (115 ) $ 5,327 $ 34 $ (22 ) $ 5,339 Segment net income (loss) (a)(b) 658 64 — 722 (2 ) (2 ) 718 Nine Months Ended September 30, 2014: Operating revenues $ 13,594 $ 1,115 $ (301 ) $ 14,408 $ 114 $ (72 ) $ 14,450 Segment net income (loss) (a)(c) 1,557 128 — 1,685 — (5 ) 1,680 Total assets at December 31, 2014 $ 64,644 $ 5,550 $ (131 ) $ 70,063 $ 1,156 $ (296 ) $ 70,923 (a) After dividends on preferred and preference stock of subsidiaries. (b) Segment net income (loss) for the traditional operating companies for the three months ended September 30, 2015 and September 30, 2014 includes pre-tax charges of $150 million ( $93 million after tax) and a pre-tax charge of $418 million ( $258 million after tax), respectively, for estimated probable losses on the Kemper IGCC. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate" herein for additional information. (c) Segment net income (loss) for the traditional operating companies for the nine months ended September 30, 2015 and September 30, 2014 includes pre-tax charges of $182 million ( $112 million after tax) and pre-tax charges of $798 million ( $493 million after tax), respectively, for estimated probable losses on the Kemper IGCC. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate" herein for additional information. Products and Services Electric Utilities' Revenues Period Retail Wholesale Other Total (in millions) Three Months Ended September 30, 2015 $ 4,701 $ 520 $ 169 $ 5,390 Three Months Ended September 30, 2014 4,558 600 169 5,327 Nine Months Ended September 30, 2015 $ 11,958 $ 1,435 $ 494 $ 13,887 Nine Months Ended September 30, 2014 12,186 1,719 503 14,408

Introduction (Policies)

Introduction (Policies)	9 Months Ended
	Sep. 30, 2015
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, 2014 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, 2015 and 2014 . 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 The Financial Accounting Standards Board's (FASB) ASC 606, Revenue from Contracts with Customers , revises the accounting for revenue recognition effective for fiscal years beginning after December 15, 2017. The registrants continue to evaluate the requirements of ASC 606. The ultimate impact of the new standard has not yet been determined. On February 18, 2015, the FASB issued Accounting Standards Update (ASU) 2015-02, Amendments to the Consolidation Analysis , which makes certain changes to both the variable interest model and the voting model, including changes to the identification of variable interests, the variable interest entity characteristics for a limited partnership or similar entity, and the primary beneficiary determination. This ASU is effective for fiscal years beginning after December 15, 2015. Southern Power continues to evaluate these requirements. The ultimate impact of this ASU on Southern Power has not yet been determined. On April 7, 2015, the FASB issued ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs . The ASU requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability and is effective for fiscal years beginning after December 15, 2015. Early adoption is permitted and each registrant intends to adopt the ASU in the fourth quarter 2015. The ASU is required to be applied retrospectively to all periods presented beginning in the year of adoption. Southern Company currently reflects unamortized debt issuance costs in unamortized debt issuance expense on its balance sheet. The traditional operating companies and Southern Power currently reflect unamortized debt issuance costs in other deferred charges and assets on their balance sheets. Upon adoption, the reclassification will not have a material impact on the results of operations, financial position, or cash flows of any registrant.
Valuation Methodologies	Valuation Methodologies The energy-related derivatives primarily consist of 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 financial products valued using the market approach. Inputs for interest rate derivatives include LIBOR interest rates, interest rate futures contracts, and occasionally, implied volatility of interest rate options. See Note (H) herein for additional information on how these derivatives are used. 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' judgment, are also obtained when available. Investments in private equity and real estate within Alabama Power's nuclear decommissioning trusts, which are reflected as "Other" in the table above, are generally classified as Level 3, as the underlying assets typically do not have observable inputs. The fund manager values these assets using various inputs and techniques depending on the nature of the underlying investments. The fair value of partnerships is determined by aggregating the value of the underlying assets. "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	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. Energy-Related Derivatives The traditional operating companies and Southern Power enter into energy-related derivatives to hedge exposures to electricity, gas, and other fuel price changes. However, due to cost-based rate regulations and other various cost recovery mechanisms, the traditional operating companies have limited exposure to market volatility in commodity fuel prices and prices of electricity. Each of the traditional operating companies manages fuel-hedging programs, implemented per the guidelines of their respective state PSCs, through the use of financial derivative contracts, which is expected to continue to mitigate price volatility. The traditional operating companies (with respect to wholesale generating capacity) and Southern Power have limited exposure to market volatility in commodity fuel prices and prices of electricity because their long-term sales contracts shift substantially all fuel cost responsibility to the purchaser. However, the traditional operating companies and Southern Power may be exposed to market volatility in energy-related commodity prices to the extent any uncontracted wholesale generating capacity is used to sell electricity. To mitigate residual risks relative to movements in electricity prices, the traditional operating companies and Southern Power may enter into physical fixed-price contracts for the purchase and sale of electricity through the wholesale electricity market. To mitigate residual risks relative to movements in gas prices, the traditional operating companies and Southern Power may enter into fixed-price contracts for natural gas purchases; however, a significant portion of contracts are priced at market. 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 operating companies' 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 and 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 industry. 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.

Introduction (Tables)

Introduction (Tables)	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Asset Retirement Obligations	As of September 30, 2015 , details of the AROs, including those related to the CCR Rule, included in Southern Company's and the traditional operating companies' Condensed Balance Sheets herein were as follows: Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Balance at beginning of year $ 2,201 $ 829 $ 1,255 $ 17 $ 48 Liabilities incurred 644 402 — 101 97 Liabilities settled (19 ) (1 ) (18 ) — — Accretion 83 38 42 1 2 Cash flow revisions 214 20 193 3 25 Balance at end of period $ 3,123 $ 1,288 $ 1,472 $ 122 $ 172

Contingencies and Regulatory 21

Contingencies and Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Recovery Balance of Each Regulatory Clause	The recovery balance of each regulatory clause follows: Regulatory Clause Balance Sheet Line Item September 30, 2015 December 31, 2014 (in millions) Rate CNP Compliance * – Under Deferred under recovered regulatory clause revenues $ — $ 2 Under recovered regulatory clause revenues, current 38 47 Rate CNP PPA – Under Deferred under recovered regulatory clause revenues 66 29 Under recovered regulatory clause revenues, current 30 27 Retail Energy Cost Recovery – Over Deferred over recovered regulatory clause revenues 128 47 Natural Disaster Reserve Other regulatory liabilities, deferred 76 84 * Formerly Known As Rate CNP Environmental The recovery balance of each regulatory clause follows: Recovery Clause Balance Sheet Location September 30, 2015 December 31, 2014 (in millions) Fuel Cost Recovery – Under Under recovered regulatory clause revenues $ 2 $ 40 Purchased Power Capacity Recovery – Over Other regulatory liabilities, current 3 — Environmental Cost Recovery - Over Other regulatory liabilities, current 5 — Environmental Cost Recovery – Under Under recovered regulatory clause revenues — 10 Energy Conservation Cost Recovery – Over Other regulatory liabilities, current 3 — Energy Conservation Cost Recovery – Under Under recovered regulatory clause revenues — 3
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), and actual costs incurred as of September 30, 2015 , as adjusted for the Court's decision, are as follows: Cost Category 2010 Project Estimate (f) Current Estimate (a) Actual Costs (in billions) Plant Subject to Cost Cap (b)(g) $ 2.40 $ 5.11 $ 4.66 Lignite Mine and Equipment 0.21 0.23 0.23 CO 2 Pipeline Facilities 0.14 0.11 0.11 AFUDC (c) 0.17 0.66 0.55 Combined Cycle and Related Assets Placed in (d)(g) — 0.02 — General Exceptions 0.05 0.10 0.08 Deferred Costs (e)(g) — 0.20 0.17 Total Kemper IGCC $ 2.97 $ 6.43 $ 5.80 (a) Amounts in the Current Estimate reflect estimated costs through June 30, 2016. (b) The 2012 MPSC CPCN Order approved a construction cost cap of up to $2.88 billion , net of the DOE Grants and excluding the Cost Cap Exceptions. The Current Estimate and 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" for additional information. The Current Estimate and Actual Costs reflect 100% of the costs of the Kemper IGCC. See note (g) for additional information. (c) Mississippi Power's original estimate included recovery of financing costs during construction rather than the accrual of AFUDC. This approach was not approved by the Mississippi PSC in 2012 as described in "Rate Recovery of Kemper IGCC Costs." The current estimate 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. (d) Incremental operating and maintenance costs related to the combined cycle and associated common facilities placed in service in August 2014, net of costs related to energy sales. See "Rate Recovery of Kemper IGCC Costs – 2013 MPSC Rate Order" for additional information. (e) The 2012 MPSC CPCN Order approved deferral of non-capital Kemper IGCC-related costs during construction as described in "Rate Recovery of Kemper IGCC Costs – Regulatory Assets and Liabilities." (f) The 2010 Project Estimate is the certificated cost estimate adjusted to include the certificated estimate for the CO 2 pipeline facilities which was approved in 2011 by the Mississippi PSC. (g) Beginning in the third quarter 2015, certain costs, including debt carrying costs (associated with placed in service and other non-construction work in progress accounts), that previously were deferred as regulatory assets are now being recognized through income; however, such costs continue to be included in the current cost estimate and actual costs at September 30, 2015.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value on a recurring basis	As of September 30, 2015 , assets and liabilities measured at fair value on a recurring basis during the period, together with the associated level of the fair value hierarchy, were as follows: Fair Value Measurements Using As of September 30, 2015: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in millions) Southern Company Assets: Energy-related derivatives $ — $ 4 $ — $ 4 Interest rate derivatives — 20 — 20 Nuclear decommissioning trusts (a) 587 869 16 1,472 Cash equivalents 747 — — 747 Other investments 9 — 1 10 Total $ 1,343 $ 893 $ 17 $ 2,253 Liabilities: Energy-related derivatives $ — $ 211 $ — $ 211 Interest rate derivatives — 36 — 36 Total $ — $ 247 $ — $ 247 Alabama Power Assets: Energy-related derivatives $ — $ 2 $ — $ 2 Nuclear decommissioning trusts (b) Domestic equity 346 72 — 418 Foreign equity 46 45 — 91 U.S. Treasury and government agency securities — 28 — 28 Corporate bonds 10 126 — 136 Mortgage and asset backed securities — 18 — 18 Other — 4 16 20 Cash equivalents 484 — — 484 Total $ 886 $ 295 $ 16 $ 1,197 Liabilities: Energy-related derivatives $ — $ 54 $ — $ 54 Interest rate derivatives — 17 — 17 Total $ — $ 71 $ — $ 71 Fair Value Measurements Using As of September 30, 2015: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (in millions) Georgia Power Assets: Energy-related derivatives $ — $ 2 $ — $ 2 Interest rate derivatives — 9 — 9 Nuclear decommissioning trusts (b) (c) Domestic equity 169 1 — 170 Foreign equity — 109 — 109 U.S. Treasury and government agency securities — 112 — 112 Municipal bonds — 74 — 74 Corporate bonds — 166 — 166 Mortgage and asset backed securities — 109 — 109 Other 16 5 — 21 Cash equivalents 37 — — 37 Total $ 222 $ 587 $ — $ 809 Liabilities: Energy-related derivatives $ — $ 16 $ — $ 16 Interest rate derivatives — 19 — 19 Total $ — $ 35 $ — $ 35 Gulf Power Assets: Cash equivalents $ 18 $ — $ — $ 18 Liabilities: Energy-related derivatives — 94 — 94 Mississippi Power Assets: Cash equivalents $ 64 $ — $ — $ 64 Liabilities: Energy-related derivatives — 47 — 47 Southern Power Assets: Interest rate derivatives $ — $ 1 $ — $ 1 Cash equivalents 103 — — 103 Total $ 103 $ 1 $ — $ 104 (a) For additional detail, see the nuclear decommissioning trusts sections for Alabama Power and Georgia Power in this table. (b) Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. (c) Includes the investment securities pledged to creditors and collateral received and excludes payables related to the securities lending program. As of September 30, 2015 , approximately $69 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, 2015 , the fair value measurements of investments calculated at net asset value per share (or its equivalent), as well as the nature and risks of those investments, were as follows: As of September 30, 2015: Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period (in millions) Southern Company Nuclear decommissioning trusts: Foreign equity funds $ 109 None Monthly 5 days Equity - commingled funds 45 None Daily Daily Debt - commingled funds 16 None Daily 5 days Other - commingled funds 5 None Daily Not applicable Other - money market funds 16 None Daily Not applicable Trust-owned life insurance 112 None Daily 15 days Cash equivalents: Money market funds 747 None Daily Not applicable Alabama Power Nuclear decommissioning trusts: Equity - commingled funds $ 45 None Daily Daily Debt - commingled funds 16 None Daily 5 days Trust-owned life insurance 112 None Daily 15 days Cash equivalents: Money market funds 484 None Daily Not applicable Georgia Power Nuclear decommissioning trusts: Foreign equity funds $ 109 None Monthly 5 days Other - commingled funds 5 None Daily Not applicable Other - money market funds 16 None Daily Not applicable Cash equivalents: Money market funds 37 None Daily Not applicable Gulf Power Cash equivalents: Money market funds $ 18 None Daily Not applicable Mississippi Power Cash equivalents: Money market funds $ 64 None Daily Not applicable Southern Power Cash equivalents: Money market funds $ 103 None Daily Not applicable
Financial instruments for which carrying amount did not equal fair value	As of September 30, 2015 , 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 $ 25,489 $ 26,099 Alabama Power $ 7,295 $ 7,558 Georgia Power $ 9,887 $ 10,231 Gulf Power $ 1,310 $ 1,338 Mississippi Power $ 2,273 $ 2,228 Southern Power $ 2,142 $ 2,149

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Earnings per Share	Shares used to compute diluted earnings per share were as follows: Three Months Ended September 30, 2015 Three Months Ended September 30, 2014 Nine Months Ended September 30, 2015 Nine Months Ended September 30, 2014 (in millions) As reported shares 910 898 910 894 Effect of options and performance share award units 2 4 3 4 Diluted shares 912 902 913 898
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 Interest (*) (in thousands) (in millions) Balance at December 31, 2014 908,502 (725 ) $ 19,949 $ 756 $ 221 $ 20,926 Net income after dividends on preferred and preference stock — — 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 interest — — — — 429 429 Distributions to noncontrolling interest — — — — (13 ) (13 ) Net income attributable to noncontrolling interest — — — — 13 13 Other — (8 ) (8 ) 3 — (5 ) Balance at September 30, 2015 912,271 (3,332 ) $ 20,664 $ 609 $ 650 $ 21,923 Balance at December 31, 2013 892,733 (5,647 ) $ 19,008 $ 756 $ — $ 19,764 Net income after dividends on preferred and preference stock — — 1,680 — — 1,680 Other comprehensive income (loss) — — 6 — — 6 Treasury stock re-issued — 4,996 225 — — 225 Stock issued 7,781 — 332 — — 332 Stock repurchased, at cost — — (5 ) — — (5 ) Cash dividends on common stock — — (1,390 ) — — (1,390 ) Other — (51 ) 1 — — 1 Balance at September 30, 2014 900,514 (702 ) $ 19,857 $ 756 $ — $ 20,613 (*) Primarily related to Southern Power Company.

Financing (Tables)

Financing (Tables)	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Credit arrangements by company	The following table outlines the committed credit arrangements by company as of September 30, 2015 : Expires Executable Term Loans Due Within One Year Company 2015 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 — 40 — 500 800 1,340 1,339 — — — 40 Georgia Power — — — — 1,750 1,750 1,732 — — — — Gulf Power 20 225 30 — — 275 275 50 — 50 195 Mississippi Power (b) 15 220 — — — 235 210 30 30 60 175 Southern Power (c) — — — — 600 600 567 — — — — Other — 70 — — — 70 70 — — — 70 Total $ 35 $ 555 $ 30 $ 1,500 $4,400 $ 6,520 $ 6,443 $ 80 $ 30 $ 110 $ 480 (a) Excludes the $8.1 billion Bridge Agreement entered into in September 2015 that will be funded only to the extent necessary to provide financing for the Merger as discussed herein. (b) Subsequent to September 30, 2015, a $15 million bank credit arrangement expired pursuant to its terms. (c) Excludes the Tranquillity Credit Agreement assumed with the acquisition of Tranquillity on August 28, 2015, which is non-recourse to Southern Power Company, the proceeds of which are being used to finance project costs related to Tranquillity's solar facility currently under construction in California. See Note (I) to the Condensed Financial Statements herein for additional information regarding Tranquillity.
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 2015 : Company Senior Note Issuances Senior Note Redemptions Revenue Bond Issuances and Reofferings of Purchased Bonds (a) Revenue Other Long-Term Debt Issuances Other Long-Term Debt Redemptions and Maturities (b) (in millions) Southern Company $ 600 $ 400 $ — $ — $ 400 $ — Alabama Power 975 250 80 134 — — Georgia Power — 525 274 268 600 20 Gulf Power — 60 13 13 — — Mississippi Power — — — — — 352 Southern Power 650 525 — — 400 3 Other — — — — — 13 Total $ 2,225 $ 1,760 $ 367 $ 415 $ 1,400 $ 388 (a) Includes a reoffering by Alabama Power of $80 million aggregate principal amount of revenue bonds purchased and held since April 2015; reofferings by Georgia Power of $104.6 million and $65 million aggregate principal amount of revenue bonds purchased and held since 2013 and April 2015, respectively; and a reoffering by Gulf Power of $13 million aggregate principal amount of revenue bonds purchased and held in July 2015. Also includes repurchases and reofferings by Georgia Power of $94.6 million and $10 million aggregate principal amount of revenue bonds in August 2015 in connection with optional tenders. (b) Includes reductions in capital lease obligations resulting from cash payments under capital leases.

Retirement Benefits (Tables)

Retirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2015
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, 2015 and 2014 were as follows: Pension Plans Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) 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 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 cost $ 163 $ 36 $ 45 $ 8 $ 9 Three Months Ended September 30, 2014 Service cost $ 53 $ 12 $ 16 $ 4 $ 3 Interest cost 109 26 39 4 5 Expected return on plan assets (161 ) (42 ) (57 ) (7 ) (8 ) Amortization: Prior service costs 6 2 2 — — Net (gain)/loss 28 7 10 1 2 Net cost $ 35 $ 5 $ 10 $ 2 $ 2 Nine Months Ended September 30, 2014 Service cost $ 160 $ 36 $ 47 $ 8 $ 8 Interest cost 326 78 115 14 15 Expected return on plan assets (484 ) (126 ) (170 ) (21 ) (22 ) Amortization: Prior service costs 19 5 7 1 1 Net (gain)/loss 83 23 30 3 4 Net cost $ 104 $ 16 $ 29 $ 5 $ 6 Postretirement Benefits Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) 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 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 cost $ 48 $ 4 $ 21 $ 2 $ 3 Three Months Ended September 30, 2014 Service cost $ 5 $ 1 $ 2 $ — $ — Interest cost 19 5 9 — — Expected return on plan assets (14 ) (6 ) (6 ) — — Amortization: Prior service costs 1 1 — — — Net (gain)/loss 1 — — — — Net cost $ 12 $ 1 $ 5 $ — $ — Nine Months Ended September 30, 2014 Service cost $ 16 $ 4 $ 5 $ 1 $ 1 Interest cost 59 15 26 2 2 Expected return on plan assets (44 ) (19 ) (19 ) (1 ) (1 ) Amortization: Prior service costs 3 3 — — — Net (gain)/loss 2 — 1 — — Net cost $ 36 $ 3 $ 13 $ 2 $ 2

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Change in Unrecognized Tax Benefits	Changes during 2015 for unrecognized tax benefits were as follows: Mississippi Power Southern Power Southern Company (in millions) Unrecognized tax benefits as of December 31, 2014 $ 165 $ 5 $ 170 Tax positions from current periods 24 7 31 Tax positions from prior periods 459 (6 ) 456 Reductions due to settlements — — — Balance as of September 30, 2015 $ 648 $ 6 $ 657
Impact on Effective Tax Rate, If Recognized	The impact on the effective tax rate, if recognized, was as follows: As of September 30, 2015 As of December 31, 2014 Mississippi Power Southern Power Southern Company Southern Company (in millions) Tax positions impacting the effective tax rate $ (2 ) $ 6 $ 7 $ 10 Tax positions not impacting the effective tax rate 650 — 650 160 Balance of unrecognized tax benefits $ 648 $ 6 $ 657 $ 170

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of derivatives	At September 30, 2015 , 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 221 2020 2017 Alabama Power 50 2018 Georgia Power 50 2017 Gulf Power 83 2020 Mississippi Power 37 2018 Southern Power 1 2016 2017
Notional amount of interest rate derivatives	At September 30, 2015 , the following interest rate derivatives were outstanding: Notional Amount Interest Rate Received Weighted Average Interest Rate Paid Hedge Maturity Date Fair Value 2015 (in millions) (in millions) Cash Flow Hedges of Forecasted Debt Alabama Power $ 200 3-month 2.93% October 2025 $ (17 ) Georgia Power 350 3-month 2.57% November 2025 (18 ) Cash Flow Hedges of Existing Debt Georgia Power 250 3-month 0.75% March 2016 — Georgia Power 200 3-month 1.01% August 2016 — Fair Value Hedges on Existing Debt Southern Company 250 1.30% 3-month August 2017 2 Southern Company 300 2.75% 3-month June 2020 8 Georgia Power 250 5.40% 3-month June 2018 3 Georgia Power 200 4.25% 3-month December 2019 5 Derivatives not Designated as Hedges Southern Power (a) 65 (b) 3-month 2.50% October 2016 (c) 1 Total $ 2,065 $ (16 ) (a) Swaption at RE Tranquillity LLC, a subsidiary of Tranquillity. See Note (I) to the Condensed Financial Statements herein for additional information regarding Tranquillity. (b) Amortizing notional amount. (c) Represents the mandatory settlement date. Settlement will be based on a 15 -year amortizing swap.
Fair value of energy-related derivatives and interest rate derivatives	At September 30, 2015 , the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at September 30, 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: Other current assets $ 3 $ 1 $ 2 $ — $ — Other deferred charges and assets 1 1 — — — Total derivatives designated as hedging instruments for regulatory purposes $ 4 $ 2 $ 2 $ — $ — N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets $ 11 $ — $ 5 $ — $ — $ — Other deferred charges and assets 8 — 4 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 19 $ — $ 9 $ — $ — $ — Derivatives not designated as hedging instruments Interest rate derivatives: Other deferred charges and assets $ 1 $ — $ — $ — $ — $ 1 Total asset derivatives $ 24 $ 2 $ 11 $ — $ — $ 1 Liability Derivatives at September 30, 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: Other current liabilities (*) $ 117 $ 36 $ 14 $ 41 $ 26 Other deferred credits and liabilities 94 18 2 53 21 Total derivatives designated as hedging instruments for regulatory purposes $ 211 $ 54 $ 16 $ 94 $ 47 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current liabilities (*) $ 36 $ 17 $ 19 $ — $ — $ — Total liability derivatives $ 247 $ 71 $ 35 $ 94 $ 47 $ — (*) Gulf Power includes current liabilities related to derivatives designated as hedging instruments in "Liabilities from risk management activities." At December 31, 2014 , the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at December 31, 2014 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: Other current assets $ 7 $ 1 $ 6 $ — $ — Other deferred charges and assets — — 1 — — Total derivatives designated as hedging instruments for regulatory purposes $ 7 $ 1 $ 7 $ — $ — N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current assets $ 7 $ — $ 5 $ — $ — $ — Other deferred charges and assets 1 — 1 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 8 $ — $ 6 $ — $ — $ — Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets $ 6 $ — $ — $ — $ — $ 5 Total asset derivatives $ 21 $ 1 $ 13 $ — $ — $ 5 Liability Derivatives at December 31, 2014 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: Other current liabilities (*) $ 118 $ 32 $ 23 $ 37 $ 26 Other deferred credits and liabilities 79 21 4 35 19 Total derivatives designated as hedging instruments for regulatory purposes $ 197 $ 53 $ 27 $ 72 $ 45 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Interest rate derivatives: Other current liabilities (*) $ 17 $ 8 $ 9 $ — $ — $ — Other deferred credits and liabilities 7 — 5 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 24 $ 8 $ 14 $ — $ — $ — Derivatives not designated as hedging instruments Energy-related derivatives: Other current liabilities $ 4 $ — $ — $ — $ — $ 4 Total liability derivatives $ 225 $ 61 $ 41 $ 72 $ 45 $ 4 (*) Gulf Power includes current liabilities related to derivatives designated as hedging instruments in "Liabilities from risk management activities."
Offsetting disclosure tables	Amounts related to energy-related derivative contracts and interest rate derivative contracts at September 30, 2015 and December 31, 2014 are presented in the following tables. Derivative Contracts at September 30, 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) $ 4 $ 2 $ 2 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (4 ) (2 ) (2 ) — — — Net energy-related derivative assets $ — $ — $ — $ — $ — $ — Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 20 $ — $ 9 $ — $ — $ 1 Gross amounts not offset in the Balance Sheet (b) (9 ) — (2 ) — — — Net interest rate derivative assets $ 11 $ — $ 7 $ — $ — $ 1 Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 211 $ 54 $ 16 $ 94 $ 47 $ — Gross amounts not offset in the Balance Sheet (b) (4 ) (2 ) (2 ) — — — Net energy-related derivative liabilities $ 207 $ 52 $ 14 $ 94 $ 47 $ — Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 36 $ 17 $ 19 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (9 ) — (2 ) — — — Net interest rate derivative liabilities $ 27 $ 17 $ 17 $ — $ — $ — (a) None of the registrants offsets fair value amounts for multiple derivative instruments executed with the same counterparty on the balance sheets; therefore, gross and net amounts of derivative assets and liabilities presented on the balance sheets are the same. (b) Includes gross amounts subject to netting terms that are not offset on the balance sheets and any cash/financial collateral pledged or received. Derivative Contracts at December 31, 2014 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) $ 13 $ 1 $ 7 $ — $ — $ 5 Gross amounts not offset in the Balance Sheet (b) (9 ) — (7 ) — — — Net energy-related derivative assets $ 4 $ 1 $ — $ — $ — $ 5 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 8 $ — $ 6 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (8 ) — (6 ) — — — Net interest rate derivative assets $ — $ — $ — $ — $ — $ — Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 201 $ 53 $ 27 $ 72 $ 45 $ 4 Gross amounts not offset in the Balance Sheet (b) (9 ) — (7 ) — — — Net energy-related derivative liabilities $ 192 $ 53 $ 20 $ 72 $ 45 $ 4 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 24 $ 8 $ 14 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (8 ) — (6 ) — — — Net interest rate derivative liabilities $ 16 $ 8 $ 8 $ — $ — $ — (a) None of the registrants offsets fair value amounts for multiple derivative instruments executed with the same counterparty on the balance sheets; therefore, gross and net amounts of derivative assets and liabilities presented on the balance sheets are the same. (b) Includes gross amounts subject to netting terms that are not offset on 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, 2015 and December 31, 2014 , 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 on the Balance Sheet at September 30, 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 $ (117 ) $ (36 ) $ (14 ) $ (41 ) $ (26 ) Other regulatory assets, deferred (94 ) (18 ) (2 ) (53 ) (21 ) Other regulatory liabilities, current (a) 3 1 2 — — Other regulatory liabilities, deferred (b) 1 1 — — — Total energy-related derivative gains (losses) $ (207 ) $ (52 ) $ (14 ) $ (94 ) $ (47 ) (a) Southern Company, Alabama Power, and Georgia Power include 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 on the Balance Sheet at December 31, 2014 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 $ (118 ) $ (32 ) $ (23 ) $ (37 ) $ (26 ) Other regulatory assets, deferred (79 ) (21 ) (4 ) (35 ) (19 ) Other regulatory liabilities, current (a) 7 1 6 — — Other regulatory liabilities, deferred (b) — — 1 — — Total energy-related derivative gains (losses) $ (190 ) $ (52 ) $ (20 ) $ (72 ) $ (45 ) (a) Southern Company, Alabama Power, and Georgia Power include other regulatory liabilities, current in other current liabilities. (b) Georgia Power includes other regulatory liabilities, deferred in other deferred credits and liabilities.
Pre-tax effects of interest rate derivatives, designated as cash flow hedging instruments	For the three months ended September 30, 2015 and 2014 , the pre-tax effects of interest rate 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 2015 2014 2015 2014 (in millions) (in millions) Southern Company Interest rate derivatives $ (28 ) $ (1 ) Interest expense, net of amounts capitalized $ (2 ) $ (2 ) Alabama Power Interest rate derivatives $ (10 ) $ (1 ) Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Georgia Power Interest rate derivatives $ (18 ) $ — Interest expense, net of amounts capitalized $ (1 ) $ (1 ) For the nine months ended September 30, 2015 and 2014 , the pre-tax effects of interest rate 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 2015 2014 2015 2014 (in millions) (in millions) Southern Company Interest rate derivatives $ (26 ) $ (1 ) Interest expense, net of amounts capitalized $ (7 ) $ (6 ) Alabama Power Interest rate derivatives $ (9 ) $ (1 ) Interest expense, net of amounts capitalized $ (2 ) $ (2 ) Georgia Power Interest rate derivatives $ (17 ) $ — Interest expense, net of amounts capitalized $ (3 ) $ (2 ) Mississippi Power Interest rate derivatives $ — $ — Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Southern Power Interest rate derivatives $ — $ — Interest expense, net of amounts capitalized $ (1 ) $ (1 )
Pre-tax effects of interest rate derivatives, designated as fair value hedging instruments	For the three months ended September 30, 2015 and 2014 , 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) Derivative Category Statements of Income Location 2015 2014 (in millions) Southern Company Interest rate derivatives: Interest expense, net of amounts capitalized $ 15 $ (1 ) Georgia Power Interest rate derivatives: Interest expense, net of amounts capitalized $ 7 $ — For the nine months ended September 30, 2015 and 2014 , 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) Derivative Category Statements of Income Location 2015 2014 (in millions) Southern Company Interest rate derivatives: Interest expense, net of amounts capitalized $ 19 $ (4 ) Georgia Power Interest rate derivatives: Interest expense, net of amounts capitalized $ 9 $ —

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2015
Business Combinations [Abstract]
Schedule of Business Acquisitions	During 2015, Southern Power Company acquired or contracted to acquire through its wholly-owned subsidiaries, Southern Renewable Partnerships, LLC or Southern Renewable Energy, Inc. (SRE), the following projects in accordance with its overall growth strategy, which are included in its capital program estimates for 2015. Acquisition-related costs were expensed as incurred and were not material. The acquisitions do not include any contingent consideration unless specifically noted. Project Entity Seller; Acquisition Date Approx. Nameplate Capacity Location Southern Power Percentage Ownership Expected/Actual Commercial Operation Date PPA PPA Contract Period Approx. Purchase Price (MW) (in millions) WIND Kay Wind, LLC Apex Clean Energy Holdings, LLC 299 Kay County, Oklahoma 100 % Fourth quarter 2015 Westar Energy, Inc. and Grant River Dam Authority 20 years $ 492 (a) Grant Wind, LLC Apex Clean Energy Holdings, LLC 151 Grant County, Oklahoma 100 % First quarter 2016 Western Farmers, East Texas, and Northeast Texas Electric Cooperative 20 years $ 264 (a) SOLAR Lost Hills Blackwell Holdings, LLC (Lost Hills Blackwell) First Solar, Inc. (First Solar) 35 Kern County, California 51 % (b) April 17, 2015 City of Roseville, California/Pacific Gas and Electric Company 29 years $ 74 (c) NS Solar Holdings, LLC (North Star) First Solar 61 Fresno County, California 51 % (b) June 20, 2015 Pacific Gas and Electric Company 20 years $ 211 (d) Tranquillity Recurrent Energy, LLC 204 Fresno County, California 51 % (b) Fourth quarter 2016 Shell Energy North America (US), LP/Southern California Edison Company 18 years $ 100 (e) Desert Stateline Holdings, LLC (Desert Stateline) First Solar 300 San Bernardino County, California 51 % (b) 8 Phases from December 2015 to Third quarter 2016 Southern California Edison Company 20 years $ 439 (f) GASNA 31P, LLC (Morelos) Solar Frontier Americas Holding, LLC 15 Kern County, California 90 % Fourth quarter 2015 Pacific Gas and Electric Company 20 years $ 45 (g) (a) On February 24, 2015 and September 4, 2015, Southern Power entered into agreements to acquire Kay Wind, LLC and Grant Wind, LLC, respectively. The completion of each acquisition is subject to the seller achieving certain construction and project milestones, as well as various other customary conditions to closing. Each acquisition is expected to close at or near the expected commercial operation date. In addition, the final purchase price may be adjusted based on performance testing as specified in the applicable purchase agreement. The Grant Wind, LLC purchase price includes contingent consideration. The ultimate outcome of this matter cannot be determined at this time. (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 respective project. In addition, Southern Power is entitled to substantially all of the federal tax benefits with respect to the respective transaction. (c) Concurrently, a wholly-owned subsidiary of First Solar acquired 100% of the class B membership interests for approximately $33 million . The fair values of the assets acquired through the business combination were recorded as follows: $98 million as property, plant, and equipment and $9 million as a receivable related to transmission interconnection costs; however, the allocation of the purchase price to individual assets has not been finalized. (d) Concurrently, a wholly-owned subsidiary of First Solar acquired 100% of the class B membership interests for approximately $100 million . The fair values of the assets acquired through the business combination were recorded as follows: $266 million as property, plant, and equipment, $24 million as an intangible asset, and $21 million as a receivable related to transmission interconnection costs; however, the allocation of the purchase price to individual assets has not been finalized. (e) Concurrently, a wholly-owned subsidiary of Recurrent Energy, LLC converted all its membership interests to 100% of the class B membership interests of Tranquillity after contributing approximately $157 million of assets and receiving an initial distribution of $100 million . The fair values of the assets acquired were recorded as follows: $170 million as CWIP, $24 million as other receivables, and $37 million as payables; however, the allocation of the purchase price to individual assets has not been finalized. Subsequent to the acquisition, Southern Power and Recurrent Energy, LLC are expected to make additional construction payments of approximately $215 million and $106 million , respectively. The ultimate outcome of this matter cannot be determined at this time. (f) Concurrently, a wholly-owned subsidiary of First Solar acquired 100% of the class B membership interests for approximately $223 million . As of September 30, 2015, the fair values of the assets acquired, which includes Southern Power's and First Solar's initial payments due under the related construction agreement, were recorded as follows: $413 million as CWIP and $249 million as an intangible asset; however, the allocation of the purchase price to individual assets has 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 $6.2 million in 2016, $12.5 million per year for 2017 through 2020, and $192.8 million thereafter. Southern Power's and First Solar's remaining combined future payments, including construction payments, are estimated to be between $827 million to $844 million . The ultimate outcome of this matter cannot be determined at this time. (g) On October 22, 2015, SRE and Turner Renewable Energy, LLC (TRE), through Southern Turner Renewable Energy, LLC, a jointly-owned subsidiary owned 90% by SRE, acquired all of the outstanding membership interests of Morelos. The total purchase price, including TRE's 10% ownership, is approximately $50 million .
Schedule of Construction Projects	Southern Power Company's construction projects, excluding the Tranquillity and Desert Stateline construction projects discussed above, are detailed in the table below: Solar Project Seller Approx. Nameplate Capacity County Location in Georgia Expected Commercial Operation Date PPA Counterparties PPA Contract Period Estimated Construction Cost (MW) (in millions) Taylor County N/A 146 Taylor Fourth quarter 2016 Cobb, Flint, and Sawnee Electric Membership Corporations 25 years $ 260 - $280 Decatur Parkway TradeWind Energy, Inc. 84 Decatur December 2015 Georgia Power (a) 25 years $ 170 - $173 (c) Decatur County TradeWind Energy, Inc. 20 Decatur December 2015 Georgia Power (b) 20 years $ 45 - $47 (c) Butler CERSM, LLC and Community Energy, Inc. 103 Taylor December 2016 Georgia Power (b) 30 years $ 220 - $230 (c) Pawpaw Longview Solar, LLC 30 Taylor December 2015 Georgia Power (a) 30 years $ 70 - $80 (c) Butler Solar Farm Strata Solar Development, LLC 20 Taylor December 2015 Georgia Power (b) 20 years $ 42 - $48 (c) (a) Approved by the FERC subsequent to September 30, 2015. (b) Subject to FERC approval. (c) Includes the acquisition price of all outstanding membership interests.

Segment and Related Informati29

Segment and Related Information (Tables)	9 Months Ended
	Sep. 30, 2015
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, 2015 and 2014 was as follows: Electric Utilities Traditional Operating Companies Southern Power Eliminations Total All Other Eliminations Consolidated (in millions) Three Months Ended September 30, 2015: 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 September 30, 2015: 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 September 30, 2015 $ 67,750 $ 7,040 $ (404 ) $ 74,386 $ 1,480 $ (651 ) $ 75,215 Three Months Ended September 30, 2014: Operating revenues $ 5,007 $ 435 $ (115 ) $ 5,327 $ 34 $ (22 ) $ 5,339 Segment net income (loss) (a)(b) 658 64 — 722 (2 ) (2 ) 718 Nine Months Ended September 30, 2014: Operating revenues $ 13,594 $ 1,115 $ (301 ) $ 14,408 $ 114 $ (72 ) $ 14,450 Segment net income (loss) (a)(c) 1,557 128 — 1,685 — (5 ) 1,680 Total assets at December 31, 2014 $ 64,644 $ 5,550 $ (131 ) $ 70,063 $ 1,156 $ (296 ) $ 70,923 (a) After dividends on preferred and preference stock of subsidiaries. (b) Segment net income (loss) for the traditional operating companies for the three months ended September 30, 2015 and September 30, 2014 includes pre-tax charges of $150 million ( $93 million after tax) and a pre-tax charge of $418 million ( $258 million after tax), respectively, for estimated probable losses on the Kemper IGCC. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate" herein for additional information. (c) Segment net income (loss) for the traditional operating companies for the nine months ended September 30, 2015 and September 30, 2014 includes pre-tax charges of $182 million ( $112 million after tax) and pre-tax charges of $798 million ( $493 million after tax), respectively, for estimated probable losses on the Kemper IGCC. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate" herein 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, 2015 $ 4,701 $ 520 $ 169 $ 5,390 Three Months Ended September 30, 2014 4,558 600 169 5,327 Nine Months Ended September 30, 2015 $ 11,958 $ 1,435 $ 494 $ 13,887 Nine Months Ended September 30, 2014 12,186 1,719 503 14,408

Introduction - Narrative (Detai

Introduction - Narrative (Details) $ in Millions	Feb. 06, 2015MW	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
Public Utility, Property, Plant and Equipment [Line Items]
Decrease to net income		$ (959)		$ (718)	$ (2,096)	$ (1,680)
Asset Retirement Obligation, Liabilities Incurred					644
Gulf Power [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Decrease in retail revenues		(363)		(366)	(983)	(979)
Decrease to net income		(48)		(47)	(120)	(117)
Asset Retirement Obligation, Liabilities Incurred		30			101
Georgia Power [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Decrease in retail revenues		(2,537)		(2,452)	(6,223)	(6,502)
Decrease to net income		$ (551)		$ (525)	(1,064)	$ (1,102)
Asset Retirement Obligation, Liabilities Incurred					$ 0
Plant Smith Units 1 and 2 [Member] | Gulf Power [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Capacity Of Units Included In Request For Decertification Of Units (in MWs) | MW	357
Restatement Adjustment [Member] | Georgia Power [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Decrease in retail revenues			$ 75
Decrease to net income			$ 47

Introduction - Asset Retirement

Introduction - Asset Retirement Obligations (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		$ 2,201
Liabilities incurred		644
Liabilities settled		(19)
Accretion		83
Cash flow revisions		214
Balance at end of period	$ 3,123	3,123
Alabama Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		829
Liabilities incurred		402
Liabilities settled		(1)
Accretion		38
Cash flow revisions		20
Balance at end of period	1,288	1,288
Georgia Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		1,255
Liabilities incurred		0
Liabilities settled		(18)
Accretion		42
Cash flow revisions		193
Balance at end of period	1,472	1,472
Gulf Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		17
Liabilities incurred	30	101
Liabilities settled		0
Accretion		1
Cash flow revisions		3
Balance at end of period	122	122
Mississippi Power [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		48
Liabilities incurred		97
Liabilities settled		0
Accretion		2
Cash flow revisions		25
Balance at end of period	$ 172	$ 172

Contingencies and Regulatory 32

Contingencies and Regulatory Matters - Recovery Balance of Each Regulatory Clause - Alabama Power (Details) - Alabama Power [Member] - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Deferred under recovered regulatory clause revenues [Member]
Loss Contingencies [Line Items]
Rate CNP Compliance – Under	$ 0	$ 2
Rate CNP PPA – Under	66	29
Under recovered regulatory clause revenues, current [Member]
Loss Contingencies [Line Items]
Rate CNP Compliance – Under	38	47
Rate CNP PPA – Under	30	27
Deferred over recovered regulatory clause revenues [Member]
Loss Contingencies [Line Items]
Retail Energy Cost Recovery – Over	128	47
Other regulatory liabilities, deferred [Member]
Loss Contingencies [Line Items]
Natural Disaster Reserve	$ 76	$ 84

Contingencies and Regulatory 33

Contingencies and Regulatory Matters - Recovery Balance of Each Regulatory Clause - Gulf Power (Details) - Gulf Power [Member] - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Under recovered regulatory clause revenues [Member]
Loss Contingencies [Line Items]
Fuel Cost Recovery – Under	$ 2	$ 40
Environmental Cost Recovery – Under	0	10
Energy Conservation Cost Recovery – Under	0	3
Other regulatory liabilities, current [Member]
Loss Contingencies [Line Items]
Purchased Power Capacity Recovery – Over	3	0
Environmental Cost Recovery - Over	5	0
Energy Conservation Cost Recovery – Over	$ 3	$ 0

Contingencies and Regulatory 34

Contingencies and Regulatory Matters - Current And Actual Cost Estimate (Details) - Mississippi Power [Member] - Kemper IGCC [Member] - USD ($) $ in Millions	1 Months Ended		9 Months Ended	12 Months Ended
	Mar. 31, 2013	Jan. 31, 2013	Sep. 30, 2015	Dec. 31, 2012
Loss Contingencies [Line Items]
Plant Subject to Cost Cap	$ 2,880	$ 2,880	$ 4,660	$ 2,880
Lignite Mine and Equipment			230
CO2 Pipeline Facilities			110
AFUDC			550
Combined Cycle and Related Assets Placed in Service – Incremental			0
General Exceptions			80
Deferred Costs			170
Total Kemper IGCC, Actual Costs			5,800
Project Estimate [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
Total Kemper IGCC, Actual Costs			2,970
Current Estimate [Member]
Loss Contingencies [Line Items]
Plant Subject to Cost Cap			5,110
Lignite Mine and Equipment			230
CO2 Pipeline Facilities			110
AFUDC			660
Combined Cycle and Related Assets Placed in Service – Incremental			20
General Exceptions			100
Deferred Costs			200
Total Kemper IGCC, Actual Costs			$ 6,430

Contingencies and Regulatory 35

Contingencies and Regulatory Matters - Narrative (Details)	Nov. 02, 2015USD ($)	Oct. 13, 2015MW	Aug. 24, 2015USD ($)MW	Jun. 03, 2015USD ($)	Apr. 16, 2015USD ($)MW	Apr. 15, 2015USD ($)	Apr. 01, 2015USD ($)	Mar. 19, 2015USD ($)	Mar. 10, 2015USD ($)	Feb. 25, 2015USD ($)	Jan. 01, 2014USD ($)	Mar. 19, 2013	Sep. 30, 2015USD ($)lawsuitmi	Jun. 30, 2015USD ($)	Apr. 30, 2015MW	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Mar. 31, 2013USD ($)	Feb. 28, 2013USD ($)	Jan. 31, 2013USD ($)	Sep. 30, 2015USD ($)lawsuitmi	Sep. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Sep. 30, 2015USD ($)clauselawsuitmiMW	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2010	Dec. 31, 2008USD ($)	Dec. 31, 2014USD ($)	Jul. 20, 2015USD ($)	Sep. 30, 2015USD ($)lawsuitmi	Jan. 01, 2016USD ($)	Oct. 27, 2015USD ($)	Oct. 06, 2015USD ($)	Sep. 18, 2015USD ($)	Sep. 01, 2015USD ($)	Aug. 31, 2015USD ($)	Aug. 13, 2015USD ($)	Jul. 10, 2015USD ($)	May. 20, 2015USD ($)	Oct. 06, 2014
Loss Contingencies [Line Items]
Revenues																					$ 5,401,000,000	$ 5,339,000,000		$ 13,921,000,000	$ 14,450,000,000
Return Of Interest Bearing Refundable Deposits Related to Assets Sale Plus Accrued Interest				$ 301,000,000
Unrecognized Tax Benefits													$ 657,000,000			$ 170,000,000					657,000,000			657,000,000		$ 170,000,000					$ 170,000,000		$ 657,000,000
Kemper IGCC [Member]
Loss Contingencies [Line Items]
Pre-Tax Charge To Income																					150,000,000	418,000,000		182,000,000	798,000,000	868,000,000	$ 1,200,000,000
After Tax Charge To Income																					93,000,000	258,000,000		112,000,000	493,000,000	536,000,000	729,000,000
Unrecognized Tax Benefits													$ 414,000,000								$ 414,000,000			$ 414,000,000									$ 414,000,000
AGL Resources [Member]
Loss Contingencies [Line Items]
Number of Class Action Lawsuits | lawsuit													4								4			4									4
Parent Company and Merger Sub [Member]
Loss Contingencies [Line Items]
Number of Class Action Lawsuits | lawsuit													2								2			2									2
Alabama Power [Member]
Loss Contingencies [Line Items]
Civil Penalties Payment Related to NSR			$ 100,000
Civil Penalties Required Investment In Electric Transportation Infrastructure Projects			$ 1,500,000
Period to Invest in Electric Transportation Infrastructure Projects			3 years
Claims Awarded to Companies Related to Nuclear Fuel Disposal Litigation																26,000,000
Non-environmental Costs																								$ 50,000,000
Recovery Of Non-environmental Costs																								50,000,000
Electric Generating Units, Capacity (in MW's) | MW															12,200
Revenues																					$ 1,695,000,000	1,669,000,000		4,551,000,000	4,614,000,000
Other Regulatory Assets Deferred													$ 1,055,000,000			1,063,000,000					1,055,000,000			1,055,000,000		1,063,000,000					1,063,000,000		$ 1,055,000,000
Projected Balance Of Regulatory Assets													118,000,000			84,000,000					118,000,000			$ 118,000,000		84,000,000					84,000,000		118,000,000
Alabama Power [Member] | Plant Gorgas Units 6 and 7 [Member]
Loss Contingencies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units (in MWs) | MW															200
Alabama Power [Member] | Plant Barry Units 1 And 2 [Member]
Loss Contingencies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units (in MWs) | MW															250
Alabama Power [Member] | Plant Greene County Units 1 And 2 [Member]
Loss Contingencies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units (in MWs) | MW																								300
Alabama Power [Member] | Plant Barry Unit 3 [Member]
Loss Contingencies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units (in MWs) | MW			225
Georgia Power [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation													29,000,000								29,000,000			$ 29,000,000									29,000,000
Civil penalties per day violation rate													$ 37,500								$ 37,500			$ 37,500									$ 37,500
Number of times of punitive damages in comparison to cost incurred by Environmental Protection Agency													3								3			3									3
Claims Awarded to Companies Related to Nuclear Fuel Disposal Litigation								$ 18,000,000
Approved Increase (Decrease) in Annual Billing Based on Fuel Cost Recovery Rate																																					$ (268,000,000)
Additional Construction Capital Costs																							$ 148,000,000								3,000,000,000
Percentage of Proportionate Share Owed in Consortium Agreement																														45.70%
Increase (Decrease) In Projected Certified Construction Capital Costs																								5.00%
Delay Of Estimated In-service Date						18 months
Revenues																					$ 2,691,000,000	2,631,000,000		$ 6,685,000,000	7,086,000,000
Other Regulatory Assets Deferred													$ 2,075,000,000			1,753,000,000					2,075,000,000			2,075,000,000		1,753,000,000					1,753,000,000		$ 2,075,000,000
Projected Balance Of Regulatory Assets													124,000,000			136,000,000					124,000,000			124,000,000		136,000,000					136,000,000		124,000,000
Georgia Power [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Additional Construction Capital Costs																														$ 114,000,000
Georgia Power [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Estimated In-service Capital Cost						$ 4,400,000,000
Georgia Power [Member] | Minimum [Member] | Plant Vogtle Units 3 And 4 [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Estimated Adjustment to Contract Price Related to Issues that May Impact Project Budget and Schedule									$ 591,000,000					$ 714,000,000										118,000,000		113,000,000				$ 425,000,000
Georgia Power [Member] | Other deferred charges and assets [Member]
Loss Contingencies [Line Items]
Fuel cost recovery balance													41,000,000			199,000,000					41,000,000			41,000,000		199,000,000					199,000,000		41,000,000
Georgia Power [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Increase in Tariff Rate Three																																		$ 49,000,000
Estimated Increase In ECCR Tariff Three																																		75,000,000
Estimated Increase In Demand Side Management Tariffs Two																																		7,000,000
Estimated Increase In Municipal Franchise Fee Tariff Three																																		13,000,000
Increase In NCCR Tariff																																		$ 19,000,000
Georgia Power [Member] | Subsequent Event [Member] | Plant Vogtle Units 3 And 4 [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Project Settlement Cost To Be Capitalized																																			$ 350,000,000
Project Settlement Cost To Be Capitalized, Amount Paid To Date																																			$ 120,000,000
Georgia Power [Member] | Plant Branch Units 1 and 3 and 4 [Member]
Loss Contingencies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units (in MWs) | MW					1,266
Georgia Power [Member] | Plant Yates Units 1 through 5 [Member]
Loss Contingencies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units (in MWs) | MW					579
Georgia Power [Member] | Plant McManus Units 1 and 2 [Member]
Loss Contingencies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units (in MWs) | MW					122
Georgia Power [Member] | Plant Mitchell Unit 3 [Member]
Loss Contingencies [Line Items]
Electric Generating Units, Capacity (in MW's) | MW					155
Georgia Power [Member] | Plant Kraft Units One Through Four [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Capacity Of Units Included In Request For Decertification Of Units (in MWs) | MW		316
Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member]
Loss Contingencies [Line Items]
Estimated In-service Capital Cost						5,000,000,000
Monthly Operational Readiness Costs						$ 10,000,000
Monthly Financing Costs																								30,000,000
Construction Financing Costs																								2,400,000,000
Southern Company [Member]
Loss Contingencies [Line Items]
Line Of Credit Expire Year Five													1,000,000,000								1,000,000,000			1,000,000,000									1,000,000,000						$ 1,000,000,000
Revenues																					5,401,000,000	5,339,000,000		13,921,000,000	14,450,000,000
Other Regulatory Assets Deferred													4,733,000,000			4,334,000,000					4,733,000,000			4,733,000,000		4,334,000,000					4,334,000,000		4,733,000,000
Projected Balance Of Regulatory Assets													421,000,000			346,000,000					421,000,000			421,000,000		346,000,000					346,000,000		421,000,000
Interest Bearing Refundable Deposit Related to Assets Sale													$ 0			275,000,000					0			0		275,000,000					275,000,000		0
Bank Loans Period Of Extension													18 months
Gulf Power [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation													$ 46,000,000								46,000,000			46,000,000									46,000,000
Reduction In Depreciation Expense																	$ 62,500,000
Reduction In Depreciation Expense Year One																								$ 20,500,000		8,400,000
Number Of Regulatory Clauses | clause																								4
Ownership percentage in scrubber project																												50.00%
Revenues																					429,000,000	438,000,000		$ 1,170,000,000	1,229,000,000
Other Regulatory Assets Deferred													430,000,000			416,000,000					430,000,000			430,000,000		416,000,000					416,000,000		430,000,000
Projected Balance Of Regulatory Assets													81,000,000			74,000,000					81,000,000			81,000,000		74,000,000					74,000,000		81,000,000
Gulf Power [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Annual Retail Revenues	$ 49,000,000
Mississippi Power [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation													300,000								300,000			300,000									300,000
AFUDC Cost							$ 13,000,000
Over Recovered Fuel Cost													44,000,000								44,000,000			44,000,000									44,000,000
PSC Retail Rate Increase (Decrease)																																						$ (2,000,000)
Ownership percentage in scrubber project																												50.00%
Estimated cost of scrubber project																												$ 330,000,000
Scrubber project expenditures amount													$ 320,000,000								320,000,000			320,000,000									$ 320,000,000
Allowance For Funds Used During Construction Cost																								32,000,000
Revenues										$ 8,000,000											$ 341,000,000	$ 355,000,000		$ 893,000,000	997,000,000
Under recovered regulatory clause revenues																2,000,000										2,000,000					2,000,000
Percentage Of PSC Retail Rate Increase (Decrease)																																						(0.35%)
Plant Capacity Under Coal Gasification Combined Cycle Technology (in MWs) | MW																								582
Co Two Pipeline Infrastructure (in miles) | mi													61								61			61									61
Costs associated with CCP12 grant funds																												$ 245,000,000
Other Property And Investments													$ 2,000,000								$ 2,000,000			$ 2,000,000									$ 2,000,000
Lignite Mining Costs													62,000,000								62,000,000			62,000,000									62,000,000
Materials, Supplies, and Other													43,000,000								43,000,000			43,000,000									43,000,000
Cost deferred in other regulatory assets													50,000,000								50,000,000			50,000,000									50,000,000
Other Regulatory Assets Deferred													460,000,000			385,000,000					460,000,000			460,000,000		385,000,000					385,000,000		460,000,000
Other deferred charges and assets													15,000,000								15,000,000			15,000,000									15,000,000
Increase Retail Rates In Year One												15.00%
Increase Retail Rates In Year Two											3.00%
Settlement Agreement Collection Amount To Mitigate Rate Impact Year Two											$ 156,000,000
Retail Rate Recovery																																$ 342,000,000
Carrying Costs Associated With Retail Rate Recovery																																	27,000,000
Projected Balance Of Regulatory Assets													$ 119,000,000			73,000,000					$ 119,000,000			$ 119,000,000		73,000,000					73,000,000		$ 119,000,000
Percentage of Carbon Dioxide Captured from Project													70.00%								70.00%			70.00%									70.00%
Percentage of Contract to Purchase Carbon Dioxide from Project													30.00%								30.00%			30.00%									30.00%
Reduced percentage interest transferred under asset purchase agreement																												15.00%
Interest Bearing Refundable Deposit Related to Assets Sale													$ 0			275,000,000					$ 0			$ 0		275,000,000					275,000,000		$ 0									$ 275,000,000
Bank Loans Period Of Extension				18 months										18 months
Issuance Of Promissory Note From Parent In Exchange For Repayment Of Interest-bearing Refundable Deposit And Accrued Interest				$ 301,000,000										$ 301,000,000										301,000,000	$ 0
Internal Revenue Code Section 48A tax credits (Phase II)																								$ 279,000,000
Minimum percentage of carbon dioxide that must be capture and sequester to remain eligible for the phase II tax credits																								65.00%
Tax credit carryforward													276,000,000								276,000,000			$ 276,000,000									276,000,000
Tax credit carryforward, utilized													235,000,000								235,000,000			235,000,000									235,000,000
Unrecognized Tax Benefits													648,000,000			165,000,000					648,000,000			648,000,000		165,000,000					165,000,000		648,000,000
Mississippi Power [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Costs Due To Extension Of In-service Date																								30,000,000
Mississippi Power [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Costs Due To Extension Of In-service Date																								25,000,000
Mississippi Power [Member] | Construction in Progress [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss													2,230,000,000								2,230,000,000			2,230,000,000									2,230,000,000
Mississippi Power [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Psc Approved Annual Property Damage Reserve Accrual																																				$ 3,000,000
Mississippi Power [Member] | MRA Revenue [Member]
Loss Contingencies [Line Items]
Over Recovered Fuel Cost													14,000,000			$ 200,000					$ 14,000,000			$ 14,000,000		200,000					$ 200,000		14,000,000
Mississippi Power [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Period of Amortization of Regulatory Assets																					24 months			9 months
AFUDC Cost							$ 10,000,000
Estimated Cost																		$ 2,880,000,000		$ 2,880,000,000				$ 4,660,000,000				$ 2,880,000,000
Other Regulatory Assets Deferred													$ 158,000,000								$ 158,000,000			158,000,000									$ 158,000,000
Pre-Tax Charge To Income																					150,000,000			182,000,000		868,000,000	1,100,000,000	78,000,000
After Tax Charge To Income																					93,000,000			112,000,000		$ 536,000,000	$ 681,000,000	48,000,000
Monthly Charge Of Allowance For Equity Funds Used During Construction																								$ 12,000,000
Monthly Cost Regulatory Assets Deferred																					$ 6,000,000
Purchase of Interest													100.00%								100.00%			100.00%									100.00%										15.00%
Maximum Cap Construction Cost																								$ 5,800,000,000
Regulatory Assets													$ 117,000,000								$ 117,000,000			117,000,000									$ 117,000,000
Projected Balance Of Regulatory Assets													91,000,000								91,000,000			91,000,000									91,000,000
Unrecognized Tax Benefits													414,000,000								414,000,000			414,000,000									414,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Current Estimate [Member]
Loss Contingencies [Line Items]
Estimated Cost																								5,110,000,000
Maximum Cap Construction Cost																								6,430,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | In-Service Asset Proposal [Member]
Loss Contingencies [Line Items]
PSC Retail Rate Increase (Decrease)													28,000,000								28,000,000			28,000,000									28,000,000							$ 159,000,000	$ 159,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Property, Plant and Equipment [Member]
Loss Contingencies [Line Items]
Estimated Cost																								3,450,000,000
Mississippi Power [Member] | Plant Watson Units 4 And 5 [Member]
Loss Contingencies [Line Items]
Net Book Value Of Units Included In Request For Decertification Of Units					$ 32,000,000
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] | Mine [Member]
Loss Contingencies [Line Items]
Term of Management Fee Contract																													40 years
Gulf Power and Mississippi Power [Member]
Loss Contingencies [Line Items]
Estimated cost of scrubber project																												$ 660,000,000
Scrubber project expenditures amount													$ 626,000,000								$ 626,000,000			$ 626,000,000									$ 626,000,000

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	$ 4
Interest rate derivatives	20
Nuclear decommissioning trusts	1,472
Cash equivalents	747
Other investments	10
Total	2,253
Liabilities:
Energy-related derivatives	211
Interest rate derivatives	36
Total	247
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
Nuclear decommissioning trusts	587
Cash equivalents	747
Other investments	9
Total	1,343
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	4
Interest rate derivatives	20
Nuclear decommissioning trusts	869
Cash equivalents	0
Other investments	0
Total	893
Liabilities:
Energy-related derivatives	211
Interest rate derivatives	36
Total	247
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Nuclear decommissioning trusts	16
Cash equivalents	0
Other investments	1
Total	17
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Alabama Power [Member]
Assets:
Energy-related derivatives	2	$ 1
Liabilities:
Energy-related derivatives	71	61
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	2
Cash equivalents	484
Total	1,197
Liabilities:
Energy-related derivatives	54
Interest rate derivatives	17
Total	71
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	418
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	91
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	28
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	136
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	18
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	20
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	484
Total	886
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	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	346
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	46
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	10
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] | 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	2
Cash equivalents	0
Total	295
Liabilities:
Energy-related derivatives	54
Interest rate derivatives	17
Total	71
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	45
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	28
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	126
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	18
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	4
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Cash equivalents	0
Total	16
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	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] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	16
Georgia Power [Member]
Assets:
Energy-related derivatives	11	13
Nuclear decommissioning trusts	69
Liabilities:
Energy-related derivatives	35	41
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	2
Interest rate derivatives	9
Cash equivalents	37
Total	809
Liabilities:
Energy-related derivatives	16
Interest rate derivatives	19
Total	35
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	170
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	109
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	112
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	74
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	166
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	109
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	21
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	37
Total	222
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	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	169
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	16
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	2
Interest rate derivatives	9
Cash equivalents	0
Total	587
Liabilities:
Energy-related derivatives	16
Interest rate derivatives	19
Total	35
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	109
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	112
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	74
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	166
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	109
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	5
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
Interest rate derivatives	0
Total	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	0	0
Liabilities:
Energy-related derivatives	94	72
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	18
Liabilities:
Energy-related derivatives	94
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Cash equivalents	18
Liabilities:
Energy-related derivatives	0
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Cash equivalents	0
Liabilities:
Energy-related derivatives	94
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Cash equivalents	0
Liabilities:
Energy-related derivatives	0
Mississippi Power [Member]
Assets:
Energy-related derivatives	0	0
Liabilities:
Energy-related derivatives	47	45
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	64
Liabilities:
Energy-related derivatives	47
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Cash equivalents	64
Liabilities:
Energy-related derivatives	0
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Cash equivalents	0
Liabilities:
Energy-related derivatives	47
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Cash equivalents	0
Liabilities:
Energy-related derivatives	0
Southern Power [Member]
Assets:
Energy-related derivatives	1	5
Liabilities:
Energy-related derivatives	0	$ 4
Southern Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Interest rate derivatives	1
Cash equivalents	103
Total	104
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Interest rate derivatives	0
Cash equivalents	103
Total	103
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Interest rate derivatives	1
Cash equivalents	0
Total	1
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Interest rate derivatives	0
Cash equivalents	0
Total	$ 0

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Measurements Calculated at Net Asset Value Per Share (Details)	9 Months Ended
	Sep. 30, 2015USD ($)
Foreign equity funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 109,000,000
Unfunded Commitments	$ 0
Redemption Notice Period	5 days
Equity - commingled funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 45,000,000
Unfunded Commitments	0
Debt - Commingled Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	16,000,000
Unfunded Commitments	$ 0
Redemption Notice Period	5 days
Other - commingled funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 5,000,000
Unfunded Commitments	0
Other - money market funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	16,000,000
Unfunded Commitments	0
Trust owned life insurance [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	112,000,000
Unfunded Commitments	$ 0
Redemption Notice Period	15 days
Money market funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 747,000,000
Unfunded Commitments	0
Alabama Power [Member] | Equity - commingled funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	45,000,000
Unfunded Commitments	0
Alabama Power [Member] | Debt - Commingled Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	16,000,000
Unfunded Commitments	$ 0
Redemption Notice Period	5 days
Alabama Power [Member] | Trust owned life insurance [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 112,000,000
Unfunded Commitments	$ 0
Redemption Notice Period	15 days
Alabama Power [Member] | Money market funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 484,000,000
Unfunded Commitments	0
Georgia Power [Member] | Foreign equity funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	109,000,000
Unfunded Commitments	$ 0
Redemption Notice Period	5 days
Georgia Power [Member] | Other - commingled funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 5,000,000
Unfunded Commitments	0
Georgia Power [Member] | Other - money market funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	16,000,000
Unfunded Commitments	0
Georgia Power [Member] | Money market funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	37,000,000
Unfunded Commitments	0
Gulf Power [Member] | Money market funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	18,000,000
Unfunded Commitments	0
Mississippi Power [Member] | Money market funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	64,000,000
Unfunded Commitments	0
Southern Power [Member] | Money market funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	103,000,000
Unfunded Commitments	$ 0

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments for which Carrying Amount did not Equal Fair Value (Details) $ in Millions	Sep. 30, 2015USD ($)
Southern Company [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	$ 25,489
Long-term debt, including securities due within one year, Fair Value	26,099
Alabama Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	7,295
Long-term debt, including securities due within one year, Fair Value	7,558
Georgia Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	9,887
Long-term debt, including securities due within one year, Fair Value	10,231
Gulf Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	1,310
Long-term debt, including securities due within one year, Fair Value	1,338
Mississippi Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	2,273
Long-term debt, including securities due within one year, Fair Value	2,228
Southern Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	2,142
Long-term debt, including securities due within one year, Fair Value	$ 2,149

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015USD ($)	Sep. 30, 2015USD ($)
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds including reinvested interest and dividends	$ (65)	$ (33)
Georgia Power [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Notices Of Withdrawal Foreign Equity Funds	20.00%	20.00%
Increase (decrease) in fair value of funds including reinvested interest and dividends	$ (26)	$ (14)
Georgia Power [Member] | Other - commingled funds [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Maximum Number of Days Related to Dollar Weighted Average Portfolio Maturities Regarding Commingled Funds		90 days
Georgia Power [Member] | Minimum [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Withdrawal Of Foreign Equity Fund Investment	1	$ 1
Foreign Equity Fund Investment	10	10
Alabama Power [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds including reinvested interest and dividends	$ (39)	$ (19)

Stockholders' Equity - Earnings

Stockholders' Equity - Earnings per Share (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	15	16	1	17
Southern Company [Member]
Earnings per Share
As reported shares	910	898	910	894
Effect of options and performance share award units	2	4	3	4
Diluted shares	912	902	913	898

Stockholders' Equity - Changes

Stockholders' Equity - Changes in Stockholders' Equity (Details) - USD ($) $ in Millions	Mar. 02, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Stock Repurchase Program, Number of Shares Authorized to be Repurchased	20,000,000
Changes in Stockholders' Equity
Beginning Balance				$ 20,926	$ 19,764
Net income after dividends on preferred and preference stock		$ 959	$ 718	2,096	1,680
Other comprehensive income (loss)				(7)	6
Treasury stock re-issued					225
Stock issued				136	332
Stock-based compensation				78
Stock repurchased, at cost, Shares	(2,600,000)
Stock repurchased, at cost				(115)	(5)
Cash dividends on common stock				(1,465)	(1,390)
Preference stock redemption				(150)
Contributions from noncontrolling interest				429
Distributions to noncontrolling interest				(13)
Net income attributable to noncontrolling interest				13
Other				(5)	1
Ending Balance		$ 21,923	$ 20,613	$ 21,923	$ 20,613
Number of Common shares Issued [Member]
Changes in Stockholders' Equity
Beginning Balance, Shares				908,502,000	892,733,000
Stock issued, Shares				3,769,000	7,781,000
Ending Balance, Shares		912,271,000	900,514,000	912,271,000	900,514,000
Number of Common shares Treasury [Member]
Changes in Stockholders' Equity
Beginning Balance, Shares				725,000	5,647,000
Treasury stock re-issued, Shares					4,996,000
Stock repurchased, at cost, Shares				(2,599,000)
Other, Shares				(8,000)	(51,000)
Ending Balance, Shares		3,332,000	702,000	3,332,000	702,000
Common Stockholders' Equity [Member]
Changes in Stockholders' Equity
Beginning Balance				$ 19,949	$ 19,008
Net income after dividends on preferred and preference stock				2,096	1,680
Other comprehensive income (loss)				(7)	6
Treasury stock re-issued					225
Stock issued				136	332
Stock-based compensation				78
Stock repurchased, at cost				(115)	(5)
Cash dividends on common stock				(1,465)	(1,390)
Other				(8)	1
Ending Balance		$ 20,664	$ 19,857	20,664	19,857
Preferred And Preference Stock [Member]
Changes in Stockholders' Equity
Beginning Balance				756	756
Stock issued					0
Preference stock redemption				(150)
Other				3
Ending Balance		609	$ 756	609	$ 756
Noncontrolling Interest [Member]
Changes in Stockholders' Equity
Beginning Balance				221
Contributions from noncontrolling interest				429
Distributions to noncontrolling interest				(13)
Net income attributable to noncontrolling interest				13
Ending Balance		$ 650		$ 650

Financing - Schedule of Credit

Financing - Schedule of Credit Arrangements (Details)	Sep. 30, 2015USD ($)
Line of Credit Facility [Line Items]
Expires, 2015	$ 35,000,000
Expires, 2016	555,000,000
Expires, 2017	30,000,000
Expires, 2018	1,500,000,000
Expires, 2020	4,400,000,000
Total	6,520,000,000
Unused	6,443,000,000
Executable Term Loans, One Year	80,000,000
Executable Term Loans, Two Years	30,000,000
Due Within One Year, Term Out	110,000,000
Due Within One Year, No Term Out	480,000,000
Southern Company [Member]
Line of Credit Facility [Line Items]
Expires, 2015	0
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, 2015	0
Expires, 2016	40,000,000
Expires, 2017	0
Expires, 2018	500,000,000
Expires, 2020	800,000,000
Total	1,340,000,000
Unused	1,339,000,000
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	40,000,000
Georgia Power [Member]
Line of Credit Facility [Line Items]
Expires, 2015	0
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, 2015	20,000,000
Expires, 2016	225,000,000
Expires, 2017	30,000,000
Expires, 2018	0
Expires, 2020	0
Total	275,000,000
Unused	275,000,000
Executable Term Loans, One Year	50,000,000
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	50,000,000
Due Within One Year, No Term Out	195,000,000
Mississippi Power [Member]
Line of Credit Facility [Line Items]
Expires, 2015	15,000,000
Expires, 2016	220,000,000
Expires, 2017	0
Expires, 2018	0
Expires, 2020	0
Total	235,000,000
Unused	210,000,000
Executable Term Loans, One Year	30,000,000
Executable Term Loans, Two Years	30,000,000
Due Within One Year, Term Out	60,000,000
Due Within One Year, No Term Out	175,000,000
Southern Power [Member]
Line of Credit Facility [Line Items]
Expires, 2015	0
Expires, 2016	0
Expires, 2017	0
Expires, 2018	0
Expires, 2020	600,000,000
Total	600,000,000
Unused	567,000,000
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, 2015	0
Expires, 2016	70,000,000
Expires, 2017	0
Expires, 2018	0
Expires, 2020	0
Total	70,000,000
Unused	70,000,000
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	70,000,000
Scenario, Plan [Member] | Bridge Agreement [Member]
Line of Credit Facility [Line Items]
Total	$ 8,100,000,000

Financing - Schedule of Long-Te

Financing - Schedule of Long-Term Debt Financing Activities (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Aug. 31, 2015	Sep. 30, 2015
Debt Instrument [Line Items]
Senior Note Issuances		$ 2,225
Senior Note Redemptions		1,760
Revenue Bond Issuances and Reofferings of Purchased Bonds		367
Revenue Bond Maturities and Repurchases		415
Other Long-Term Debt Issuances		1,400
Other Long-Term Debt Redemptions and Maturities		388
Southern Company [Member]
Debt Instrument [Line Items]
Senior Note Issuances		600
Senior Note Redemptions		400
Revenue Bond Issuances and Reofferings of Purchased Bonds		0
Revenue Bond Maturities and Repurchases		0
Other Long-Term Debt Issuances		400
Other Long-Term Debt Redemptions and Maturities		0
Alabama Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		975
Senior Note Redemptions		250
Revenue Bond Issuances and Reofferings of Purchased Bonds		80
Revenue Bond Maturities and Repurchases		134
Other Long-Term Debt Issuances		0
Other Long-Term Debt Redemptions and Maturities		0
Alabama Power [Member] | Debt Held Since 2015 [Member]
Debt Instrument [Line Items]
Revenue Bond Issuances and Reofferings of Purchased Bonds		80
Georgia Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		0
Senior Note Redemptions		525
Revenue Bond Issuances and Reofferings of Purchased Bonds		274
Revenue Bond Maturities and Repurchases		268
Other Long-Term Debt Issuances		600
Other Long-Term Debt Redemptions and Maturities		20
Georgia Power [Member] | Debt Held Since 2015 [Member]
Debt Instrument [Line Items]
Revenue Bond Issuances and Reofferings of Purchased Bonds		65
Georgia Power [Member] | Debt Held Since 2009 [Member]
Debt Instrument [Line Items]
Revenue Bond Issuances and Reofferings of Purchased Bonds	$ 94.6
Georgia Power [Member] | Debt Held Since 2013 [Member]
Debt Instrument [Line Items]
Revenue Bond Issuances and Reofferings of Purchased Bonds	$ 10	104.6
Gulf Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		0
Senior Note Redemptions		60
Revenue Bond Issuances and Reofferings of Purchased Bonds		13
Revenue Bond Maturities and Repurchases		13
Other Long-Term Debt Issuances		0
Other Long-Term Debt Redemptions and Maturities		0
Gulf Power [Member] | Debt Held Since 2015 [Member]
Debt Instrument [Line Items]
Revenue Bond Issuances and Reofferings of Purchased Bonds		13
Mississippi Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		0
Senior Note Redemptions		0
Revenue Bond Issuances and Reofferings of Purchased Bonds		0
Revenue Bond Maturities and Repurchases		0
Other Long-Term Debt Issuances		0
Other Long-Term Debt Redemptions and Maturities		352
Southern Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances		650
Senior Note Redemptions		525
Revenue Bond Issuances and Reofferings of Purchased Bonds		0
Revenue Bond Maturities and Repurchases		0
Other Long-Term Debt Issuances		400
Other Long-Term Debt Redemptions and Maturities		3
Other [Member]
Debt Instrument [Line Items]
Senior Note Issuances		0
Senior Note Redemptions		0
Revenue Bond Issuances and Reofferings of Purchased Bonds		0
Revenue Bond Maturities and Repurchases		0
Other Long-Term Debt Issuances		0
Other Long-Term Debt Redemptions and Maturities		$ 13

Financing - Narrative (Details)

Financing - Narrative (Details) $ / shares in Units, shares in Thousands	Nov. 05, 2015USD ($)	Jul. 15, 2015USD ($)	Jun. 03, 2015USD ($)	Sep. 30, 2015USD ($)	Aug. 31, 2015USD ($)	Jun. 30, 2015USD ($)	May. 31, 2015USD ($)$ / sharesshares	Apr. 30, 2015USD ($)loan	Sep. 30, 2015USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Mar. 31, 2015USD ($)
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support				$ 1,800,000,000					$ 1,800,000,000	$ 1,800,000,000
Ratio of Indebtedness to Capitalization Covenant				70.00%	65.00%				70.00%	70.00%
Line Of Credit Expire Year Four				$ 1,500,000,000					$ 1,500,000,000	$ 1,500,000,000
Line of Credit Facility, Maximum Borrowing Capacity				6,520,000,000					6,520,000,000	6,520,000,000
Line of Credit Expire Year One				35,000,000					35,000,000	35,000,000
Derivative, Notional Amount				2,065,000,000					2,065,000,000	2,065,000,000
Revenue Bond Issuances and Reofferings of Purchased Bonds										367,000,000
Scenario, Plan [Member]
Debt Instrument [Line Items]
Expected Equity Issuance				1,000,000,000					1,000,000,000	1,000,000,000
Scenario, Plan [Member] | Bridge Agreement [Member]
Debt Instrument [Line Items]
Expected Debt Issuance				7,000,000,000					7,000,000,000	7,000,000,000
Expected Equity Issuance				2,000,000,000					2,000,000,000	2,000,000,000
Line of Credit Facility, Maximum Borrowing Capacity				8,100,000,000					$ 8,100,000,000	8,100,000,000
Period After Funding That Loan Will Mature And Be Payable in Full									364 days
Alabama Power [Member]
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support				810,000,000					$ 810,000,000	810,000,000
Amount of Fixed Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support				200,000,000					200,000,000	200,000,000
Line Of Credit Expire Year Four				500,000,000					500,000,000	$ 500,000,000
Debt Instrument, Term										3 years
Line of Credit Facility, Maximum Borrowing Capacity				1,340,000,000					1,340,000,000	$ 1,340,000,000
Line of Credit Expire Year One				0					0	0
Revenue Bond Issuances and Reofferings of Purchased Bonds										80,000,000
Repayments of Senior Debt										250,000,000	$ 0
Alabama Power [Member] | 5.20% Class A Preferred Stock [Member]
Debt Instrument [Line Items]
Temporary Equity, Shares Outstanding | shares							6,480
Temporary Equity, Dividend Rate Percentage							0.052
Redemption price (in dollars per share) | $ / shares							$ 25
Alabama Power [Member] | 5.30% Class A Preferred Stock [Member]
Debt Instrument [Line Items]
Temporary Equity, Shares Outstanding | shares							4,000
Temporary Equity, Dividend Rate Percentage							0.053
Redemption price (in dollars per share) | $ / shares							$ 25
Alabama Power [Member] | 5.625% Series Preference Stock [Member]
Debt Instrument [Line Items]
Temporary Equity, Shares Outstanding | shares							6,000
Temporary Equity, Dividend Rate Percentage							0.05625
Redemption price (in dollars per share) | $ / shares							$ 25
Alabama Power [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Remarketed Pollution Control Bonds	$ 120,000,000
Alabama Power [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Redemption Amount Of Principal Notes												$ 250,000,000
Alabama Power [Member] | Series 2015A [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount								$ 175,000,000				$ 550,000,000
Debt Instrument, Interest Rate, Stated Percentage								3.75%				3.75%
Alabama Power [Member] | Series DD [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage												5.65%
Alabama Power [Member] | Series 2007B [Member]
Debt Instrument [Line Items]
Remarketing Revenue Bond								$ 80,000,000
Alabama Power [Member] | Series 2015B [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount								$ 250,000,000
Debt Instrument, Interest Rate, Stated Percentage								2.80%
Alabama Power [Member] | Aggregate Stated Capital [Member] | 5.20% Class A Preferred Stock [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 162,000,000
Alabama Power [Member] | Aggregate Stated Capital [Member] | 5.30% Class A Preferred Stock [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							100,000,000
Alabama Power [Member] | Aggregate Stated Capital [Member] | 5.625% Series Preference Stock [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							150,000,000
Georgia Power [Member]
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support				872,000,000					872,000,000	872,000,000
Amount of Fixed Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support				121,000,000					121,000,000	121,000,000
Line of Credit Facility, Increase (Decrease), Net					$ 150,000,000
Line Of Credit Expire Year Three Terminated					150,000,000
Line Of Credit Expire Year Four				0					0	0
Line of Credit Facility, Maximum Borrowing Capacity				1,750,000,000					1,750,000,000	1,750,000,000
Line of Credit Expire Year One				0					0	0
Line of Credit Facility, Current Borrowing Capacity						$ 600,000,000
Period Of Amortization Of Gain (Loss) On Settlement Of Derivatives						10 years
Revenue Bond Issuances and Reofferings of Purchased Bonds										274,000,000
Repayments of Senior Debt										525,000,000	0
Georgia Power [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Gain (Loss) on Settlement Of Derivatives						$ (6,000,000)
Georgia Power [Member] | Interest Rate Swap [Member] | Cash Flow Hedges Of Forecasted Debt [Member] | Maturity Date May 2025 [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount						$ 350,000,000
Georgia Power [Member] | Second Series 2008 [Member]
Debt Instrument [Line Items]
Long-term Pollution Control Bond								$ 65,000,000
Georgia Power [Member] | Debt Held Since 2013 [Member]
Debt Instrument [Line Items]
Remarketing Revenue Bond							104,600,000
Revenue Bond Issuances and Reofferings of Purchased Bonds					10,000,000					104,600,000
Georgia Power [Member] | Debt Due 2044 [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage						3.283%
Georgia Power [Member] | Debt Held Since 2009 [Member]
Debt Instrument [Line Items]
Revenue Bond Issuances and Reofferings of Purchased Bonds					94,600,000
Gulf Power [Member]
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support				82,000,000					82,000,000	82,000,000
Amount of Fixed Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support				33,000,000					33,000,000	33,000,000
Line Of Credit Expire Year Four				0					0	0
Line of Credit Facility, Maximum Borrowing Capacity				275,000,000					275,000,000	275,000,000
Line of Credit Expire Year One				20,000,000					20,000,000	20,000,000
Revenue Bond Issuances and Reofferings of Purchased Bonds										13,000,000
Repayments of Senior Debt										60,000,000	0
Mississippi Power [Member]
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support				40,000,000					40,000,000	40,000,000
Line Of Credit Expire Year Four				0					0	0
Line of Credit Facility, Maximum Borrowing Capacity				235,000,000					235,000,000	235,000,000
Line of Credit Expire Year One				15,000,000					15,000,000	15,000,000
Aggregate Principal Amount Of Floating Rate Bank Loan								$ 475,000,000
Bank Loans Period Of Extension			18 months			18 months
Revenue Bond Issuances and Reofferings of Purchased Bonds										0
Number Of Floating Rate Bank Loans | loan								3
Repayment Aggregate Principal Amount Of Floating Rate Bank Loan								$ 275,000,000
Promissory Note			$ 301,000,000			$ 301,000,000				301,000,000	0
Mississippi Power [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Line of Credit Expire Year One	15,000,000
Mississippi Power [Member] | Debt Due 2016 [Member]
Debt Instrument [Line Items]
Aggregate Principal Amount Of Floating Rate Bank Loan								$ 425,000,000
Number Of Floating Rate Bank Loans | loan								2
Traditional Operating Companies [Member]
Debt Instrument [Line Items]
Amount of Fixed Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support				354,000,000					354,000,000	354,000,000
Southern Company [Member]
Debt Instrument [Line Items]
Expires, 2020				1,250,000,000					1,250,000,000	1,250,000,000
Line Of Credit Expire Year Five				1,000,000,000	1,000,000,000				1,000,000,000	1,000,000,000
Line Of Credit Expire Year Four				1,000,000,000					1,000,000,000	1,000,000,000
Line of Credit Facility, Maximum Borrowing Capacity				2,250,000,000					2,250,000,000	2,250,000,000
Line of Credit Expire Year One				0					0	0
Aggregate Principal Amount Of Floating Rate Bank Loan				$ 400,000,000					400,000,000	400,000,000
Bank Loans Period Of Extension				18 months
Revenue Bond Issuances and Reofferings of Purchased Bonds										0
Southern Company [Member] | Series 2015A [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 600,000,000
Debt Instrument, Interest Rate, Stated Percentage						2.75%
Southern Company [Member] | Series 2015A [Member] | Junior Subordinated Debt [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,000,000,000
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Southern Power [Member]
Debt Instrument [Line Items]
Expires, 2020				$ 600,000,000					600,000,000	600,000,000
Line Of Credit Expire Year Five					500,000,000
Line Of Credit Expire Year Four				0					0	0
Line of Credit Facility, Maximum Borrowing Capacity				600,000,000					600,000,000	600,000,000
Line of Credit Expire Year One				$ 0					$ 0	0
Aggregate Principal Amount Of Floating Rate Bank Loan					$ 400,000,000
Bank Loans Period Of Extension					13 months
Revenue Bond Issuances and Reofferings of Purchased Bonds										0
Repayments of Senior Debt										525,000,000	$ 0
Early Repayment of Senior Debt										$ 2,600,000
Southern Power [Member] | Series 2015A [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 350,000,000
Debt Instrument, Interest Rate, Stated Percentage							1.50%
Southern Power [Member] | Series 2015B [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 300,000,000
Debt Instrument, Interest Rate, Stated Percentage							2.375%
Southern Power [Member] | Series 2003 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		4.875%
Repayments of Senior Debt		$ 525,000,000

Retirement Benefits (Details)

Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Plans [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	$ 65	$ 53	$ 193	$ 160
Interest cost	111	109	333	326
Expected return on plan assets	(181)	(161)	(543)	(484)
Amortization:
Prior service costs	6	6	19	19
Net (gain)/loss	53	28	161	83
Net cost	54	35	163	104
Pension Plans [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	14	12	44	36
Interest cost	26	26	79	78
Expected return on plan assets	(44)	(42)	(133)	(126)
Amortization:
Prior service costs	2	2	5	5
Net (gain)/loss	14	7	41	23
Net cost	12	5	36	16
Pension Plans [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	18	16	54	47
Interest cost	38	39	115	115
Expected return on plan assets	(62)	(57)	(188)	(170)
Amortization:
Prior service costs	2	2	7	7
Net (gain)/loss	19	10	57	30
Net cost	15	10	45	29
Pension Plans [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	4	9	8
Interest cost	5	4	15	14
Expected return on plan assets	(8)	(7)	(24)	(21)
Amortization:
Prior service costs	1	0	1	1
Net (gain)/loss	2	1	7	3
Net cost	3	2	8	5
Pension Plans [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	3	9	8
Interest cost	5	5	16	15
Expected return on plan assets	(8)	(8)	(25)	(22)
Amortization:
Prior service costs	0	0	1	1
Net (gain)/loss	3	2	8	4
Net cost	3	2	9	6
Other Postretirement Benefits [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	6	5	17	16
Interest cost	20	19	59	59
Expected return on plan assets	(15)	(14)	(44)	(44)
Amortization:
Prior service costs	1	1	3	3
Net (gain)/loss	4	1	13	2
Net cost	16	12	48	36
Other Postretirement Benefits [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	1	4	4
Interest cost	5	5	15	15
Expected return on plan assets	(6)	(6)	(19)	(19)
Amortization:
Prior service costs	2	1	3	3
Net (gain)/loss	0	0	1	0
Net cost	2	1	4	3
Other Postretirement Benefits [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	2	5	5
Interest cost	9	9	26	26
Expected return on plan assets	(6)	(6)	(18)	(19)
Amortization:
Prior service costs	0	0	0	0
Net (gain)/loss	2	0	8	1
Net cost	7	5	21	13
Other Postretirement Benefits [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	0	1	1
Interest cost	0	0	2	2
Expected return on plan assets	0	0	(1)	(1)
Amortization:
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	1	0	2	2
Other Postretirement Benefits [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	0	1	1
Interest cost	1	0	3	2
Expected return on plan assets	0	0	(1)	(1)
Amortization:
Prior service costs	0	0	0	0
Net (gain)/loss	0	0	0	0
Net cost	$ 1	$ 0	$ 3	$ 2

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Operating loss carryforwards			$ 24
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of December 31, 2014	$ 170
Tax positions from current periods	31
Tax positions from prior periods	456
Reductions due to settlements	0
Balance as of September 30, 2015	657
Tax positions impacting the effective tax rate	7			$ 10
Tax positions not impacting the effective tax rate	650			160
Kemper IGCC [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of September 30, 2015	414
Unrecognized tax benefit, associated interest	7
Southern Power [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 212			$ 305
Effective tax rate	6.90%	14.40%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of December 31, 2014	$ 5
Tax positions from current periods	7
Tax positions from prior periods	(6)
Reductions due to settlements	0
Balance as of September 30, 2015	6
Tax positions impacting the effective tax rate	6
Tax positions not impacting the effective tax rate	$ 0
Mississippi Power [Member]
Income Tax Contingency [Line Items]
Effective tax rate	(20.90%)	(45.50%)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of December 31, 2014	$ 165
Tax positions from current periods	24
Tax positions from prior periods	459
Reductions due to settlements	0
Balance as of September 30, 2015	648
Tax positions impacting the effective tax rate	(2)
Tax positions not impacting the effective tax rate	650
Internal Revenue Code Section 48A tax credits (Phase II)	$ 279
Minimum percentage of carbon dioxide that must be capture and sequester to remain eligible for the phase II tax credits	65.00%
Tax credit carryforward	$ 276
Tax credit carryforward, utilized	235
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, 2015	414
Unrecognized tax benefit, associated interest	$ 7

Derivatives - Schedule of Deriv

Derivatives - Schedule of Derivatives and Gains (Losses) (Details) BTU in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)BTU
Notional amount of interest rate derivatives
Notional Amount	$ 2,065
Fair Value Gain (Loss) at September 30, 2015	(16)
Southern Company [Member] | Maturity Date August 2017 [Member] | Fair Value Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 250
Interest Rate Received	1.30%
Fair Value Gain (Loss) at September 30, 2015	$ 2
Southern Company [Member] | Maturity Date August 2017 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Weighted Average Interest Rate Paid	0.17%
Southern Company [Member] | Maturity Date June 2020 [Member] | Fair Value Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 300
Interest Rate Received	2.75%
Fair Value Gain (Loss) at September 30, 2015	$ 8
Southern Company [Member] | Maturity Date June 2020 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Weighted Average Interest Rate Paid	0.92%
Southern Company [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	221
Alabama Power [Member] | Maturity Date October 2025 [Member] | Cash Flow Hedges Of Forecasted Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 200
Weighted Average Interest Rate Paid	2.93%
Fair Value Gain (Loss) at September 30, 2015	$ (17)
Alabama Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	50
Georgia Power [Member] | Maturity Date November 2025 [Member] | Cash Flow Hedges Of Forecasted Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 350
Weighted Average Interest Rate Paid	2.57%
Fair Value Gain (Loss) at September 30, 2015	$ (18)
Georgia Power [Member] | Maturity Date March 2016 [Member] | Cash Flow Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 250
Weighted Average Interest Rate Paid	0.75%
Fair Value Gain (Loss) at September 30, 2015	$ 0
Georgia Power [Member] | Maturity Date March 2016 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Cash Flow Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Interest Rate Received	0.32%
Georgia Power [Member] | Maturity Date August 2016 [Member] | Cash Flow Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 200
Weighted Average Interest Rate Paid	1.01%
Fair Value Gain (Loss) at September 30, 2015	$ 0
Georgia Power [Member] | Maturity Date August 2016 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Cash Flow Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Interest Rate Received	0.40%
Georgia Power [Member] | Maturity Date June 2018 [Member] | Fair Value Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 250
Interest Rate Received	5.40%
Fair Value Gain (Loss) at September 30, 2015	$ 3
Georgia Power [Member] | Maturity Date June 2018 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Weighted Average Interest Rate Paid	4.02%
Georgia Power [Member] | Maturity Date December 2019 [Member] | Fair Value Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 200
Interest Rate Received	4.25%
Fair Value Gain (Loss) at September 30, 2015	$ 5
Georgia Power [Member] | Maturity Date December 2019 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Fair Value Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Weighted Average Interest Rate Paid	2.46%
Georgia Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	50
Gulf Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	83
Mississippi Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	37
Southern Power [Member] | Maturity Date October 2016 [Member] | Not Designated as Hedging Instrument [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 65
Weighted Average Interest Rate Paid	2.50%
Fair Value Gain (Loss) at September 30, 2015	$ 1
Derivative, Term of Contract	15 years
Southern Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	1

Derivatives - Balance Sheet Pre

Derivatives - Balance Sheet Presentation (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	$ 1
Southern Company [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	24	$ 21
Derivatives, liabilities	247	225
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		6
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		4
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	4	7
Derivatives, liabilities	211	197
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	3	7
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	0
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	117	118
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	94	79
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	19	8
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		24
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	11	7
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	8	1
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	36	17
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		7
Alabama Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	1
Derivatives, liabilities	71	61
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] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	1
Derivatives, liabilities	54	53
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	1
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	0
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	36	32
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	18	21
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		8
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	17	8
Alabama Power [Member] | Cash Flow and Fair Value Hedging [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	11	13
Derivatives, liabilities	35	41
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] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	7
Derivatives, liabilities	16	27
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	6
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	1
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	14	23
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	2	4
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	9	6
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		14
Georgia Power [Member] | Cash Flow and Fair Value Hedging [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] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	4	1
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	19	9
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		5
Gulf Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	94	72
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] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	94	72
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	41	37
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	53	35
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [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	0	0
Derivatives, liabilities	47	45
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets		0
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	47	45
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	26	26
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	21	19
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Southern Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	5
Derivatives, liabilities	0	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		5
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		4
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other current liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	$ 0	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		$ 0

Derivatives - Balance Sheet Off

Derivatives - Balance Sheet Offsetting (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Southern Company [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	$ 24	$ 21
Derivatives presented in the Balance Sheet, liabilities	247	225
Southern Company [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	0	4
Net interest rate derivative liabilities	207	192
Southern Company [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	4	13
Derivatives presented in the Balance Sheet, liabilities	211	201
Southern Company [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	(4)	(9)
Gross amounts not offset in the Balance Sheet, liabilities	(4)	(9)
Southern Company [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	11	0
Net interest rate derivative liabilities	27	16
Southern Company [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	20	8
Derivatives presented in the Balance Sheet, liabilities	36	24
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)	(8)
Gross amounts not offset in the Balance Sheet, liabilities	(9)	(8)
Alabama Power [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	2	1
Derivatives presented in the Balance Sheet, liabilities	71	61
Alabama Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	0	1
Net interest rate derivative liabilities	52	53
Alabama Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	2	1
Derivatives presented in the Balance Sheet, liabilities	54	53
Alabama Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	(2)	0
Gross amounts not offset in the Balance Sheet, liabilities	(2)	0
Alabama Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	17	8
Alabama Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	0
Derivatives presented in the Balance Sheet, liabilities	17	8
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	0
Gross amounts not offset in the Balance Sheet, liabilities	0	0
Georgia Power [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	11	13
Derivatives presented in the Balance Sheet, liabilities	35	41
Georgia Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	14	20
Georgia Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	2	7
Derivatives presented in the Balance Sheet, liabilities	16	27
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)	(7)
Gross amounts not offset in the Balance Sheet, liabilities	(2)	(7)
Georgia Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	7	0
Net interest rate derivative liabilities	17	8
Georgia Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	9	6
Derivatives presented in the Balance Sheet, liabilities	19	14
Georgia Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	(2)	(6)
Gross amounts not offset in the Balance Sheet, liabilities	(2)	(6)
Gulf Power [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	0
Derivatives presented in the Balance Sheet, liabilities	94	72
Gulf Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	94	72
Gulf Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	0
Derivatives presented in the Balance Sheet, liabilities	94	72
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	0
Gross amounts not offset in the Balance Sheet, liabilities	0	0
Gulf Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	0	0
Gulf Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	0
Derivatives presented in the Balance Sheet, liabilities	0	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	0
Gross amounts not offset in the Balance Sheet, liabilities	0	0
Mississippi Power [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	0
Derivatives presented in the Balance Sheet, liabilities	47	45
Mississippi Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	47	45
Mississippi Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	0
Derivatives presented in the Balance Sheet, liabilities	47	45
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	0
Gross amounts not offset in the Balance Sheet, liabilities	0	0
Mississippi Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	0	0
Mississippi Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	0
Derivatives presented in the Balance Sheet, liabilities	0	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	0
Gross amounts not offset in the Balance Sheet, liabilities	0	0
Southern Power [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	1	5
Derivatives presented in the Balance Sheet, liabilities	0	4
Southern Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	0	5
Net interest rate derivative liabilities	0	4
Southern Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	5
Derivatives presented in the Balance Sheet, liabilities	0	4
Southern Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	0	0
Gross amounts not offset in the Balance Sheet, liabilities	0	0
Southern Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	1	0
Net interest rate derivative liabilities	0	0
Southern Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	1	0
Derivatives presented in the Balance Sheet, liabilities	0	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	0
Gross amounts not offset in the Balance Sheet, liabilities	$ 0	$ 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, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Southern Company [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	$ (207)		$ (207)		$ (190)
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	(117)		(117)		(118)
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	(94)		(94)		(79)
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	3		3		7
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		0
Southern Company [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(28)	$ (1)	(26)	$ (1)
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)	(2)	(2)	(7)	(6)
Alabama Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(52)		(52)		(52)
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	(36)		(36)		(32)
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	(18)		(18)		(21)
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	1		1		0
Alabama Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(10)	(1)	(9)	(1)
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)	(1)	(1)	(2)	(2)
Georgia Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(14)		(14)		(20)
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	(14)		(14)		(23)
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	(2)		(2)		(4)
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	2		2		6
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	0		0		1
Georgia Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(18)	0	(17)	0
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)	(2)
Gulf Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(94)		(94)		(72)
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	(41)		(41)		(37)
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	(53)		(53)		(35)
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		0
Mississippi Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(47)		(47)		(45)
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	(26)		(26)		(26)
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	(21)		(21)		(19)
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		$ 0
Mississippi Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)			0	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] | 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)

Derivatives - Pre-tax Effects51

Derivatives - Pre-tax Effects of Derivatives Designated as Fair Value Hedging Instruments (Details) - Interest Rate Contract [Member] - Interest Expense [Member] - Fair Value Hedging [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Southern Company [Member]
Derivative [Line Items]
Gain (Loss)	$ 15	$ (1)	$ 19	$ (4)
Georgia Power [Member]
Derivative [Line Items]
Gain (Loss)	$ 7	$ 0	$ 9	$ 0

Derivatives - Narrative (Detail

Derivatives - Narrative (Details) BTU in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)BTU
Derivative [Line Items]
Maximum Potential Collateral Requirements Arising from Credit Risk Related Contingent Features | $	$ 54
Southern Company [Member]
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	5
Georgia Power [Member]
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	4
Southern Power [Member]
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints	1

Acquisitions - Schedule of Acqu

Acquisitions - Schedule of Acquisitions (Details) $ in Millions	Oct. 22, 2015USD ($)MW	Sep. 04, 2015USD ($)MW	Aug. 31, 2015USD ($)MW	Aug. 28, 2015USD ($)MW	Apr. 30, 2015USD ($)MW	Apr. 15, 2015USD ($)MW	Feb. 24, 2015USD ($)MW	Sep. 30, 2015USD ($)MW	Dec. 31, 2014USD ($)
Southern Power [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW								146
PPA Contract Period								25 years
Construction in Progress, Gross								$ 977	$ 11
Southern Power [Member] | Class A Membership Interest [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership								100.00%
Southern Power [Member] | Kay Wind, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Wind (MW) | MW							299
Southern Power Percentage Ownership							100.00%
PPA Contract Period							20 years
Approx. Purchase Price							$ 492
Southern Power [Member] | Grant Wind, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Wind (MW) | MW		151
Southern Power Percentage Ownership		100.00%
PPA Contract Period		20 years
Approx. Purchase Price		$ 264
Southern Power [Member] | Lost Hills Blackwell Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW						35
Southern Power Percentage Ownership						51.00%
PPA Contract Period						29 years
Approx. Purchase Price						$ 74
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment								$ 98
Reimbursable Transmission Costs Receivable								9
Southern Power [Member] | Lost Hills Blackwell Holdings, LLC [Member] | Class A Membership Interest [Member]
Business Acquisition [Line Items]
Percentage Of Entitled Cash Distributions						51.00%
Southern Power [Member] | NS Solar Holdings, LLC (North Star) [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW					61
Southern Power Percentage Ownership					51.00%
PPA Contract Period					20 years
Approx. Purchase Price					$ 211
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment								266
Reimbursable Transmission Costs Receivable								21
Purchased Power Agreement Intangible								24
Southern Power [Member] | RE Tranquility Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW				204
Southern Power Percentage Ownership				51.00%
PPA Contract Period				18 years
Approx. Purchase Price				$ 100
Reimbursable Transmission Costs Receivable				24
Construction in Progress, Gross				170
Construction Payable				37
Estimated Future Construction Payments								215
Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW			300
Southern Power Percentage Ownership			51.00%
PPA Contract Period			20 years
Approx. Purchase Price			$ 439
Purchased Power Agreement Intangible			249
Construction in Progress, Gross			413
Southern Power [Member] | Subsequent Event [Member] | GASNA 31P, LLC (Morelos) [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	15
Southern Power Percentage Ownership	90.00%
PPA Contract Period	20 years
Approx. Purchase Price	$ 45
Southern Power [Member] | Scenario, Plan [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months								6.2
Finite-Lived Intangible Assets, Amortization Expense, Year Two Through Five								12.5
Finite-Lived Intangible Assets, Amortization Expense, Year Six and Thereafter								$ 192.8
Southern Power [Member] | Turner Renewable Energy [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	10.00%
First Solar [Member] | Class B Membership Interest [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership								100.00%
First Solar [Member] | Lost Hills Blackwell Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Purchase Price						$ 33
First Solar [Member] | Lost Hills Blackwell Holdings, LLC [Member] | Class B Membership Interest [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership						100.00%
Percentage Of Entitled Cash Distributions						49.00%
First Solar [Member] | NS Solar Holdings, LLC (North Star) [Member]
Business Acquisition [Line Items]
Approx. Purchase Price			$ 100
First Solar [Member] | NS Solar Holdings, LLC (North Star) [Member] | Class B Membership Interest [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership			100.00%
First Solar [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Purchase Price			$ 223
First Solar [Member] | Desert Stateline Holdings, LLC [Member] | Class B Membership Interest [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership			100.00%
Recurrent Energy [Member] | RE Tranquility Holdings, LLC [Member]
Business Acquisition [Line Items]
Contribution of Assets				157
Initial Distribution Received				$ 100
Estimated Future Construction Payments								$ 106
Recurrent Energy [Member] | RE Tranquility Holdings, LLC [Member] | Class B Membership Interest [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership				100.00%
Southern Power and First Solar [Member] | Minimum [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Estimated Future Construction Payments								827
Southern Power and First Solar [Member] | Maximum [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Estimated Future Construction Payments								$ 844
SRE and Turner Renewable Energy [Member] | Subsequent Event [Member] | GASNA 31P, LLC (Morelos) [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership	90.00%
Southern Power and Turner Renewable Energy [Member] | Subsequent Event [Member] | GASNA 31P, LLC (Morelos) [Member]
Business Acquisition [Line Items]
Approx. Purchase Price	$ 50

Acquisitions - Schedule of Cons

Acquisitions - Schedule of Construction Projects (Details) - Southern Power [Member] $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)MW
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	146
PPA Contract Period	25 years
Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 260
Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 280
Decatur Parkway Solar Project, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	84
PPA Contract Period	25 years
Decatur Parkway Solar Project, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 170
Decatur Parkway Solar Project, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 173
Decatur County Solar Project, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	20
PPA Contract Period	20 years
Decatur County Solar Project, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 45
Decatur County Solar Project, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 47
Butler Solar LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	103
PPA Contract Period	30 years
Butler Solar LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 220
Butler Solar LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 230
LS Pawpaw, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	30
PPA Contract Period	30 years
LS Pawpaw, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 70
LS Pawpaw, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 80
Butler Solar Farm, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	20
PPA Contract Period	20 years
Butler Solar Farm, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 42
Butler Solar Farm, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Cost	$ 48

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details)	Aug. 23, 2015USD ($)$ / shares	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)
Business Acquisition [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 6,520,000,000
Scenario, Plan [Member]
Business Acquisition [Line Items]
Expected Equity Issuance		1,000,000,000
Scenario, Plan [Member] | Bridge Agreement [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price | $ / shares	$ 66
Approx. Purchase Price	$ 8,200,000,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	8,000,000,000
Business Combination, Acquisition Related Costs	$ 200,000,000
Expected Debt Issuance		7,000,000,000
Expected Equity Issuance		2,000,000,000
Line of Credit Facility, Maximum Borrowing Capacity		8,100,000,000
AGL Resources [Member] | Scenario, Plan [Member] | Bridge Agreement [Member]
Business Acquisition [Line Items]
Business Exit Costs		201,000,000
Early Termination Reimbursable Expenses		5,000,000
Southern Power [Member]
Business Acquisition [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 600,000,000
Number of Businesses Acquired		5
Total Cost		$ 299,000,000
Southern Power [Member] | SG2 Holdings, LLC [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			$ 707,000,000
Prepaid Long Term Service Agreements			$ 20,000,000

Segment and Related Informati56

Segment and Related Information - Financial Data for Business Segments (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015USD ($)state	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)state	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Segment Reporting Information [Line Items]
Number of States in which Entity Operates | state	4		4
Operating revenues	$ 5,401	$ 5,339	$ 13,921	$ 14,450
Segment net income (loss)	959	718	2,096	1,680
Total assets	75,215		75,215		$ 70,923
Kemper IGCC [Member]
Segment Reporting Information [Line Items]
Pre-Tax Charge To Income	150	418	182	798	868	$ 1,200
After Tax Charge To Income	93	258	112	493	536	$ 729
Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,390	5,327	13,887	14,408
Segment net income (loss)	976	722	2,093	1,685
Total assets	74,386		74,386		70,063
Intersegment Eliminations [Member] | Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	(109)	(115)	(322)	(301)
Segment net income (loss)	0	0	0	0
Total assets	(404)		(404)		(131)
Consolidation Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	(26)	(22)	(86)	(72)
Segment net income (loss)	1	(2)	0	(5)
Total assets	(651)		(651)		(296)
Traditional Operating Companies [Member] | Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,098	5,007	13,123	13,594
Segment net income (loss)	874	658	1,912	1,557
Total assets	67,750		67,750		64,644
Southern Power [Member]
Segment Reporting Information [Line Items]
Operating revenues	104	103	303	243
Southern Power [Member] | Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	401	435	1,086	1,115
Segment net income (loss)	102	64	181	128
Total assets	7,040		7,040		5,550
All Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	37	34	120	114
Segment net income (loss)	(18)	$ (2)	3	$ 0
Total assets	$ 1,480		$ 1,480		$ 1,156

Segment and Related Informati57

Segment and Related Information - Financial Data for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	$ 5,390	$ 5,327	$ 13,887	$ 14,408
Retail [Member]
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	4,701	4,558	11,958	12,186
Wholesale [Member]
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	520	600	1,435	1,719
Other [Member]
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	$ 169	$ 169	$ 494	$ 503