Mississippi Power (MSPWP) 10-Q 5 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	3 Months Ended
	Mar. 31, 2016shares
Document Information [Line Items]
Entity Registrant Name	SOUTHERN CO
Entity Central Index Key	92,122
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	918,258,425
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
	Mar. 31, 2016	Mar. 31, 2015
Operating Revenues:
Retail revenues	$ 3,377	$ 3,542
Wholesale revenues	396	467
Other electric revenues	181	163
Other revenues	11	11
Total operating revenues	3,965	4,183
Operating Expenses:
Fuel	911	1,212
Purchased power	165	144
Other operations and maintenance	1,106	1,122
Depreciation and amortization	541	487
Taxes other than income taxes	256	252
Estimated loss on Kemper IGCC	53	9
Total operating expenses	3,032	3,226
Operating Income (Loss)	933	957
Other Income and (Expense):
Allowance for equity funds used during construction	53	63
Interest expense, net of amounts capitalized	(246)	(213)
Other income (expense), net	(21)	(8)
Total other income and (expense)	(214)	(158)
Earnings Before Income Taxes	719	799
Income taxes (benefit)	222	274
Net Income (Loss)	497	525
Less: Net income attributable to noncontrolling interests	1	0
Dividends on preferred and preference stock of subsidiaries	11	17
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	$ 485	$ 508
Earnings per share (EPS) -
Basic EPS (in dollars per share)	$ 0.53	$ 0.56
Diluted EPS (in dollars per share)	$ 0.53	$ 0.56
Average number of shares of common stock outstanding (in millions)
Basic (in shares)	916	910
Diluted (in shares)	922	915
Cash dividends paid per share of common stock (in dollars per share)	$ 0.5425	$ 0.525
Alabama Power [Member]
Operating Revenues:
Retail revenues	$ 1,193	$ 1,268
Wholesale revenues, non-affiliates	63	65
Wholesale revenues, affiliates	22	15
Other revenues	53	53
Total operating revenues	1,331	1,401
Operating Expenses:
Fuel	268	310
Purchased power, non-affiliates	36	41
Purchased power, affiliates	33	53
Other operations and maintenance	392	399
Depreciation and amortization	172	158
Taxes other than income taxes	97	94
Total operating expenses	998	1,055
Operating Income (Loss)	333	346
Other Income and (Expense):
Allowance for equity funds used during construction	10	15
Interest expense, net of amounts capitalized	(73)	(65)
Other income (expense), net	(8)	(4)
Total other income and (expense)	(71)	(54)
Earnings Before Income Taxes	262	292
Income taxes (benefit)	103	113
Net Income (Loss)	159	179
Dividends on preferred and preference stock of subsidiaries	4	10
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	155	169
Georgia Power [Member]
Operating Revenues:
Retail revenues	1,717	1,814
Wholesale revenues, non-affiliates	41	68
Wholesale revenues, affiliates	5	8
Other revenues	109	88
Total operating revenues	1,872	1,978
Operating Expenses:
Fuel	376	526
Purchased power, non-affiliates	83	60
Purchased power, affiliates	139	149
Other operations and maintenance	457	474
Depreciation and amortization	211	216
Taxes other than income taxes	97	99
Total operating expenses	1,363	1,524
Operating Income (Loss)	509	454
Other Income and (Expense):
Allowance for equity funds used during construction	14	15
Interest expense, net of amounts capitalized	(94)	(89)
Other income (expense), net	17	15
Total other income and (expense)	(77)	(74)
Earnings Before Income Taxes	432	380
Income taxes (benefit)	160	140
Net Income (Loss)	272	240
Dividends on preferred and preference stock of subsidiaries	4	4
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	268	236
Gulf Power [Member]
Operating Revenues:
Retail revenues	283	293
Wholesale revenues, non-affiliates	16	25
Wholesale revenues, affiliates	21	22
Other revenues	15	17
Total operating revenues	335	357
Operating Expenses:
Fuel	94	110
Purchased power, non-affiliates	30	25
Purchased power, affiliates	2	9
Other operations and maintenance	77	93
Depreciation and amortization	38	20
Taxes other than income taxes	29	28
Total operating expenses	270	285
Operating Income (Loss)	65	72
Other Income and (Expense):
Allowance for equity funds used during construction	0	4
Interest expense, net of amounts capitalized	(13)	(13)
Other income (expense), net	(1)	(1)
Total other income and (expense)	(14)	(10)
Earnings Before Income Taxes	51	62
Income taxes (benefit)	20	23
Net Income (Loss)	31	39
Dividends on preferred and preference stock of subsidiaries	2	2
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	29	37
Mississippi Power [Member]
Operating Revenues:
Retail revenues	183	167
Wholesale revenues, non-affiliates	60	77
Wholesale revenues, affiliates	9	27
Other revenues	5	5
Total operating revenues	257	276
Operating Expenses:
Fuel	76	114
Purchased power, non-affiliates	0	2
Purchased power, affiliates	5	2
Other operations and maintenance	69	73
Depreciation and amortization	38	27
Taxes other than income taxes	26	25
Estimated loss on Kemper IGCC	53	9
Total operating expenses	267	252
Operating Income (Loss)	(10)	24
Other Income and (Expense):
Allowance for equity funds used during construction	29	28
Interest expense, net of amounts capitalized	(16)	(11)
Other income (expense), net	(2)	(2)
Total other income and (expense)	11	15
Earnings Before Income Taxes	1	39
Income taxes (benefit)	(10)	4
Net Income (Loss)	11	35
Dividends on preferred and preference stock of subsidiaries	0	0
Net Income (Loss) After Dividends on Preferred and Preference Stock of Subsidiaries	11	35
Southern Power [Member]
Operating Revenues:
Wholesale revenues, non-affiliates	215	232
Wholesale revenues, affiliates	97	114
Other revenues	3	2
Total operating revenues	315	348
Operating Expenses:
Fuel	91	138
Purchased power, non-affiliates	13	16
Purchased power, affiliates	6	10
Other operations and maintenance	79	52
Depreciation and amortization	73	59
Taxes other than income taxes	6	6
Total operating expenses	268	281
Operating Income (Loss)	47	67
Other Income and (Expense):
Interest expense, net of amounts capitalized	(21)	(22)
Other income (expense), net	2	0
Total other income and (expense)	(19)	(22)
Earnings Before Income Taxes	28	45
Income taxes (benefit)	(23)	12
Net Income (Loss)	51	33
Less: Net income attributable to noncontrolling interests	1	0
Net income attributable to Southern Power Company	$ 50	$ 33

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net Income (loss)	$ 497	$ 525
Qualifying hedges:
Changes in fair value, net of tax	(117)	(18)
Reclassification adjustment for amounts included in net income, net of tax	2	1
Pension and other post retirement benefit plans:
Reclassification adjustment for amounts included in net income, net of tax	1	2
Total other comprehensive income (loss)	(114)	(15)
Dividends on preferred and preference stock of subsidiaries	11	17
Comprehensive income attributable to noncontrolling interests	1	0
Comprehensive Income (Loss)	371	493
Alabama Power [Member]
Net Income (loss)	159	179
Qualifying hedges:
Changes in fair value, net of tax	(2)	(4)
Reclassification adjustment for amounts included in net income, net of tax	1	0
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	(1)	(4)
Dividends on preferred and preference stock of subsidiaries	4	10
Comprehensive Income (Loss)	158	175
Georgia Power [Member]
Net Income (loss)	272	240
Qualifying hedges:
Changes in fair value, net of tax	0	(14)
Reclassification adjustment for amounts included in net income, net of tax	1	0
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	1	(14)
Dividends on preferred and preference stock of subsidiaries	4	4
Comprehensive Income (Loss)	273	226
Gulf Power [Member]
Net Income (loss)	31	39
Qualifying hedges:
Changes in fair value, net of tax	(3)	0
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	(3)	0
Dividends on preferred and preference stock of subsidiaries	2	2
Comprehensive Income (Loss)	28	39
Mississippi Power [Member]
Net Income (loss)	11	35
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	0	0
Dividends on preferred and preference stock of subsidiaries	0	0
Comprehensive Income (Loss)	11	35
Southern Power [Member]
Net Income (loss)	51	33
Qualifying hedges:
Reclassification adjustment for amounts included in net income, net of tax	1	0
Pension and other post retirement benefit plans:
Total other comprehensive income (loss)	1	0
Comprehensive income attributable to noncontrolling interests	1	0
Comprehensive Income (Loss)	$ 51	$ 33

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Changes in fair value, tax	$ (72)	$ (11)
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	1	1
Reclassification adjustment for amounts of pension and other post retirement benefit plans included in net income, tax	1	1
Alabama Power [Member]
Changes in fair value, tax	(1)	(2)
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	1	0
Gulf Power [Member]
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	(2)	0
Southern Power [Member]
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	0	0
Georgia Power [Member]
Changes in fair value, tax	0	(9)
Reclassification adjustment for amounts of qualifying hedges included in net income, tax	$ 0	$ 0

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities:
Net income (loss)	$ 497	$ 525
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	639	578
Deferred income taxes	(4)	113
Allowance for equity funds used during construction	(53)	(63)
Stock based compensation expense	58	56
Estimated loss on Kemper IGCC	53	9
Other, net	(13)	4
Changes in certain current assets and liabilities —
-Receivables	235	180
-Fossil fuel stock	31	76
-Materials and supplies	(14)	4
-Other current assets	(90)	(89)
-Accounts payable	(72)	(426)
-Accrued taxes	(60)	197
-Accrued compensation	(332)	(381)
-Retail fuel cost over recovery - short-term	25	49
-Mirror CWIP	0	40
-Other current liabilities	(35)	41
Net cash provided from (used for) operating activities	865	913
Investing Activities:
Plant acquisitions	(114)	(6)
Property additions	(1,872)	(1,091)
Investment in restricted cash	(289)	0
Distributions of restricted cash	292	0
Nuclear decommissioning trust fund purchases	(316)	(290)
Nuclear decommissioning trust fund sales	311	284
Cost of removal, net of salvage	(52)	(36)
Change in construction payables	(94)	65
Prepaid long-term service agreement	(49)	(37)
Other investing activities	(14)	4
Net cash used for investing activities	(2,197)	(1,107)
Financing Activities:
Increase (decrease) in notes payable, net	294	597
Proceeds —
Long-term debt issuances	1,997	550
Common stock issuances	270	112
Short-term borrowings	0	280
Redemptions and repurchases —
Long-term debt	(888)	(333)
Common stock	0	(115)
Short-term borrowings	(475)	0
Capital contributions from noncontrolling interests	131	0
Purchase of membership interests from noncontrolling interests	(4)	0
Purchase of Membership Interests from Noncontrolling Interests	(129)	0
Payment of common stock dividends	(497)	(478)
Other financing activities	(17)	(17)
Net cash provided from (used for) financing activities	682	596
Net Change in Cash and Cash Equivalents	(650)	402
Cash and Cash Equivalents at Beginning of Period	1,404	710
Cash and Cash Equivalents at End of Period	754	1,112
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	224	207
Income taxes, net	(141)	(289)
Noncash transactions - Accrued property additions at end of period	731	347
Alabama Power [Member]
Operating Activities:
Net income (loss)	159	179
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	211	196
Deferred income taxes	68	16
Allowance for equity funds used during construction	(10)	(15)
Other, net	(3)	2
Changes in certain current assets and liabilities —
-Receivables	191	(3)
-Fossil fuel stock	(27)	0
-Materials and supplies	(8)	12
-Other current assets	(79)	(80)
-Accounts payable	(143)	(229)
-Accrued taxes	64	246
-Accrued compensation	(75)	(89)
-Retail fuel cost over recovery - short-term	(1)	34
-Other current liabilities	(8)	21
Net cash provided from (used for) operating activities	339	290
Investing Activities:
Property additions	(313)	(325)
Nuclear decommissioning trust fund purchases	(105)	(129)
Nuclear decommissioning trust fund sales	105	129
Cost of removal, net of salvage	(31)	(13)
Change in construction payables	(15)	34
Other investing activities	(9)	(9)
Net cash used for investing activities	(368)	(313)
Proceeds —
Senior notes issuances	400	550
Capital contributions from parent company	236	6
Other long-term debt	45	0
Redemptions and repurchases —
Senior notes	(200)	(250)
Payment of common stock dividends	(191)	(143)
Other financing activities	(11)	(18)
Net cash provided from (used for) financing activities	279	145
Net Change in Cash and Cash Equivalents	250	122
Cash and Cash Equivalents at Beginning of Period	194	273
Cash and Cash Equivalents at End of Period	444	395
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	76	68
Income taxes, net	(162)	(136)
Noncash transactions - Accrued property additions at end of period	106	41
Georgia Power [Member]
Operating Activities:
Net income (loss)	272	240
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	261	256
Deferred income taxes	55	(7)
Allowance for equity funds used during construction	(14)	(15)
Deferred expenses	38	33
Other, net	(9)	4
Changes in certain current assets and liabilities —
-Receivables	155	166
-Fossil fuel stock	36	67
-Prepaid income taxes	38	170
-Other current assets	12	(13)
-Accounts payable	4	(261)
-Accrued taxes	(235)	(217)
-Accrued compensation	(66)	(81)
-Other current liabilities	16	21
Net cash provided from (used for) operating activities	563	363
Investing Activities:
Property additions	(553)	(422)
Nuclear decommissioning trust fund purchases	(211)	(161)
Nuclear decommissioning trust fund sales	206	155
Cost of removal, net of salvage	(15)	(16)
Change in construction payables, net of joint owner portion	(101)	37
Prepaid long-term service agreement	(11)	(9)
Other investing activities	(4)	11
Net cash used for investing activities	(689)	(405)
Financing Activities:
Increase (decrease) in notes payable, net	(158)	434
Proceeds —
Senior notes issuances	650	0
Capital contributions from parent company	218	11
Short-term borrowings	0	250
Redemptions and repurchases —
Pollution control revenue bonds	(4)	0
Senior notes	(250)	0
Payment of common stock dividends	(326)	(259)
Other financing activities	(11)	(5)
Net cash provided from (used for) financing activities	119	431
Net Change in Cash and Cash Equivalents	(7)	389
Cash and Cash Equivalents at Beginning of Period	67	24
Cash and Cash Equivalents at End of Period	60	413
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	86	79
Income taxes, net	(88)	(34)
Noncash transactions - Accrued property additions at end of period	290	177
Gulf Power [Member]
Operating Activities:
Net income (loss)	31	39
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	40	22
Deferred income taxes	9	27
Allowance for equity funds used during construction	0	(4)
Other, net	(2)	11
Changes in certain current assets and liabilities —
-Receivables	35	12
-Fossil fuel stock	15	(2)
-Other current assets	2	5
-Accounts payable	(6)	(28)
-Accrued taxes	13	5
-Accrued compensation	(18)	(16)
-Other current liabilities	13	10
Net cash provided from (used for) operating activities	132	81
Investing Activities:
Property additions	(32)	(84)
Cost of removal, net of salvage	(2)	(5)
Change in construction payables	(6)	(1)
Other investing activities	(2)	(2)
Net cash used for investing activities	(42)	(92)
Financing Activities:
Increase (decrease) in notes payable, net	(85)	40
Proceeds —
Common stock issuances	0	20
Redemptions and repurchases —
Payment of common stock dividends	(30)	(33)
Other financing activities	(1)	0
Net cash provided from (used for) financing activities	(116)	27
Net Change in Cash and Cash Equivalents	(26)	16
Cash and Cash Equivalents at Beginning of Period	74	39
Cash and Cash Equivalents at End of Period	48	55
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	3	3
Income taxes, net	(25)	(8)
Noncash transactions - Accrued property additions at end of period	15	41
Mississippi Power [Member]
Operating Activities:
Net income (loss)	11	35
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	39	26
Deferred income taxes	(4)	141
Allowance for equity funds used during construction	(29)	(28)
Regulatory assets associated with Kemper IGCC	(6)	(27)
Estimated loss on Kemper IGCC	53	9
Other, net	1	11
Changes in certain current assets and liabilities —
-Receivables	45	17
-Fossil fuel stock	6	4
-Prepaid income taxes	(3)	44
-Other current assets	(5)	(3)
-Accounts payable	(22)	(22)
-Accrued taxes	(61)	(54)
-Accrued interest	2	9
-Accrued compensation	(16)	(20)
-Over recovered regulatory clause revenues	9	22
-Mirror CWIP	0	40
-Customer liability associated with Kemper refunds	(51)	0
-Other current liabilities	6	0
Net cash provided from (used for) operating activities	(25)	204
Investing Activities:
Property additions	(197)	(213)
Change in construction payables	(7)	(14)
Other investing activities	(10)	(6)
Net cash used for investing activities	(214)	(233)
Proceeds —
Capital contributions from parent company	1	76
Short-term borrowings	0	30
Long-term debt issuance to parent company	200	0
Other long-term debt	900	0
Redemptions and repurchases —
Short-term borrowings	(475)	0
Other long-term debt	(425)	(75)
Other financing activities	(2)	(1)
Net cash provided from (used for) financing activities	199	30
Net Change in Cash and Cash Equivalents	(40)	1
Cash and Cash Equivalents at Beginning of Period	98	133
Cash and Cash Equivalents at End of Period	58	134
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	12	(1)
Income taxes, net	(24)	(180)
Noncash transactions - Accrued property additions at end of period	97	100
Southern Power [Member]
Operating Activities:
Net income (loss)	51	33
Adjustments to reconcile net income (loss) to net cash provided from operating activities —
Depreciation and amortization, total	75	60
Deferred income taxes	(132)	(54)
Amortization of investment tax credits	(7)	(4)
Deferred revenues	(26)	(20)
Other, net	9	3
Changes in certain current assets and liabilities —
-Receivables	(3)	2
-Fossil fuel stock	1	6
-Prepaid income taxes	(31)	(2)
-Accounts payable	(12)	(25)
-Accrued taxes	(37)	(4)
-Accrued interest	2	(15)
-Other current liabilities	0	1
Net cash provided from (used for) operating activities	(110)	(19)
Investing Activities:
Plant acquisitions	(114)	(6)
Property additions	(767)	(33)
Investment in restricted cash	(289)	0
Distributions of restricted cash	292	0
Change in construction payables	31	17
Payments pursuant to long-term service agreements	(25)	(16)
Other investing activities	(1)	0
Net cash used for investing activities	(873)	(38)
Financing Activities:
Increase (decrease) in notes payable, net	276	38
Redemptions and repurchases —
Capital contributions from noncontrolling interests	131	0
Purchase of membership interests from noncontrolling interests	(4)	0
Purchase of Membership Interests from Noncontrolling Interests	(129)	0
Payment of common stock dividends	(68)	(33)
Net cash provided from (used for) financing activities	206	5
Net Change in Cash and Cash Equivalents	(777)	(52)
Cash and Cash Equivalents at Beginning of Period	830	75
Cash and Cash Equivalents at End of Period	53	23
Cash paid (received) during the period for --
Interest (net of capitalized amounts)	15	36
Income taxes, net	188	79
Noncash transactions - Accrued property additions at end of period	$ 262	$ 16

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net cash paid for capitalized interest	$ 30	$ 32
Alabama Power [Member]
Net cash paid for capitalized interest	4	5
Georgia Power [Member]
Net cash paid for capitalized interest	5	6
Gulf Power [Member]
Net cash paid for capitalized interest	0	2
Mississippi Power [Member]
Interest paid	22	17
Net cash paid for capitalized interest	10	18
Southern Power [Member]
Net cash paid for capitalized interest	$ 10	$ 0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 754	$ 1,404
Receivables —
Customer accounts receivable	988	1,058
Unbilled revenues	380	397
Under recovered regulatory clause revenues	43	63
Income taxes receivable, current	0	144
Other accounts and notes receivable	236	398
Accumulated provision for uncollectible accounts	(13)	(13)
Fossil fuel stock, at average cost	837	868
Materials and supplies, at average cost	1,085	1,061
Vacation pay	181	178
Other regulatory assets, current	394	402
Prepaid expenses	486	495
Other current assets	90	71
Total current assets	5,461	6,526
Property, Plant, and Equipment:
In service	76,553	75,118
Less accumulated provision for depreciation	24,566	24,253
Plant in service, net of depreciation	51,987	50,865
Other utility plant, net	218	233
Nuclear fuel, at amortized cost	941	934
Construction work in progress	9,406	9,082
Total property, plant, and equipment	62,552	61,114
Other Property and Investments:
Nuclear decommissioning trusts, at fair value	1,540	1,512
Leveraged leases	761	755
Miscellaneous property and investments	488	485
Total other property and investments	2,789	2,752
Deferred Charges and Other Assets:
Deferred charges related to income taxes	1,572	1,560
Unamortized loss on reacquired debt	220	227
Other regulatory assets, deferred	4,957	4,989
Income taxes receivable, non-current	413	413
Other deferred charges and assets	771	737
Total deferred charges and other assets	7,933	7,926
Total Assets	78,735	78,318
Current Liabilities:
Securities due within one year	2,392	2,674
Notes payable	1,195	1,376
Accounts payable —
Accounts payable	1,584	1,905
Customer deposits	406	404
Accrued taxes —
Accrued income taxes	14	19
Other accrued taxes	240	484
Accrued interest	255	249
Accrued vacation pay	228	228
Accrued compensation	212	549
Asset retirement obligations, current	237	217
Liabilities from risk management activities	319	156
Other regulatory liabilities, current	210	278
Other current liabilities	564	590
Total current liabilities	7,856	9,129
Long-term Debt:
Total Long-term Debt	26,091	24,688
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	12,274	12,322
Deferred credits related to income taxes	185	187
Accumulated deferred investment tax credits	1,350	1,219
Employee benefit obligations	2,546	2,582
Asset retirement obligations, deferred	3,504	3,542
Unrecognized tax benefits	375	370
Other cost of removal obligations	1,151	1,162
Other regulatory liabilities, deferred	303	254
Other deferred credits and liabilities	754	720
Total deferred credits and other liabilities	22,442	22,358
Total Liabilities	56,389	56,175
Redeemable Preferred Stock of Subsidiaries	118	118
Redeemable Noncontrolling Interest	44	43
Common Stockholders' Equity:
Common stock	4,604	4,572
Paid-in capital	6,582	6,282
Treasury, at cost	(144)	(142)
Retained earnings (accumulated deficit)	9,999	10,010
Accumulated other comprehensive income (loss)	(244)	(130)
Total common stockholders' equity	20,797	20,592
Preferred and Preference Stock of Subsidiaries	609	609
Noncontrolling Interests	778	781
Total Stockholders' Equity	22,184	21,982
Total Liabilities and Stockholders' Equity	78,735	78,318
Alabama Power [Member]
Current Assets:
Cash and cash equivalents	444	194
Receivables —
Customer accounts receivable	311	332
Unbilled revenues	113	119
Under recovered regulatory clause revenues	22	43
Income taxes receivable, current	0	142
Other accounts and notes receivable	25	20
Affiliated companies	38	50
Accumulated provision for uncollectible accounts	(10)	(10)
Fossil fuel stock, at average cost	266	239
Materials and supplies, at average cost	406	398
Vacation pay	67	66
Other regulatory assets, current	99	115
Prepaid expenses	129	83
Other current assets	10	10
Total current assets	1,920	1,801
Property, Plant, and Equipment:
In service	25,187	24,750
Less accumulated provision for depreciation	8,791	8,736
Plant in service, net of depreciation	16,396	16,014
Nuclear fuel, at amortized cost	359	363
Construction work in progress	550	801
Total property, plant, and equipment	17,305	17,178
Other Property and Investments:
Equity investments in unconsolidated subsidiaries	68	71
Nuclear decommissioning trusts, at fair value	746	737
Miscellaneous property and investments	99	96
Total other property and investments	913	904
Deferred Charges and Other Assets:
Deferred charges related to income taxes	520	522
Deferred under recovered regulatory clause revenues	105	99
Other regulatory assets, deferred	1,105	1,114
Other deferred charges and assets	109	103
Total deferred charges and other assets	1,839	1,838
Total Assets	21,977	21,721
Current Liabilities:
Securities due within one year	200	200
Accounts payable —
Affiliated accounts payable	258	278
Other accounts payable	271	410
Customer deposits	88	88
Accrued taxes —
Accrued income taxes	11	0
Other accrued taxes	62	38
Accrued interest	65	73
Accrued vacation pay	55	55
Accrued compensation	47	119
Liabilities from risk management activities	37	55
Other regulatory liabilities, current	175	240
Other current liabilities	39	39
Total current liabilities	1,308	1,595
Long-term Debt:
Total Long-term Debt	6,894	6,654
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	4,306	4,241
Deferred credits related to income taxes	69	70
Accumulated deferred investment tax credits	116	118
Employee benefit obligations	377	388
Asset retirement obligations, deferred	1,461	1,448
Other cost of removal obligations	705	722
Other regulatory liabilities, deferred	119	136
Deferred over recovered regulatory clause revenues	64	0
Other deferred credits and liabilities	78	76
Total deferred credits and other liabilities	7,295	7,199
Total Liabilities	15,497	15,448
Redeemable Preferred Stock	85	85
Preference Stock	196	196
Common Stockholders' Equity:
Common stock	1,222	1,222
Paid-in capital	2,585	2,341
Retained earnings (accumulated deficit)	2,425	2,461
Accumulated other comprehensive income (loss)	(33)	(32)
Total common stockholders' equity	6,199	5,992
Total Liabilities and Stockholders' Equity	21,977	21,721
Georgia Power [Member]
Current Assets:
Cash and cash equivalents	60	67
Receivables —
Customer accounts receivable	509	541
Unbilled revenues	182	188
Joint owner accounts receivable	73	227
Income taxes receivable, current	0	114
Other accounts and notes receivable	37	57
Affiliated companies	16	18
Accumulated provision for uncollectible accounts	(2)	(2)
Fossil fuel stock, at average cost	366	402
Materials and supplies, at average cost	463	449
Vacation pay	92	91
Other regulatory assets, current	126	123
Prepaid income taxes	118	156
Other current assets	61	92
Total current assets	2,101	2,523
Property, Plant, and Equipment:
In service	32,318	31,841
Less accumulated provision for depreciation	11,045	10,903
Plant in service, net of depreciation	21,273	20,938
Other utility plant, net	158	171
Nuclear fuel, at amortized cost	582	572
Construction work in progress	4,817	4,775
Total property, plant, and equipment	26,830	26,456
Other Property and Investments:
Equity investments in unconsolidated subsidiaries	60	64
Nuclear decommissioning trusts, at fair value	793	775
Miscellaneous property and investments	43	43
Total other property and investments	896	882
Deferred Charges and Other Assets:
Deferred charges related to income taxes	680	679
Other regulatory assets, deferred	2,138	2,152
Other deferred charges and assets	157	173
Total deferred charges and other assets	2,975	3,004
Total Assets	32,802	32,865
Current Liabilities:
Securities due within one year	458	712
Notes payable	0	158
Accounts payable —
Affiliated accounts payable	370	411
Other accounts payable	549	750
Customer deposits	266	264
Accrued taxes —
Accrued income taxes	0	12
Other accrued taxes	101	325
Accrued interest	102	99
Accrued vacation pay	62	62
Accrued compensation	60	142
Asset retirement obligations, current	184	179
Other current liabilities	211	181
Total current liabilities	2,363	3,295
Long-term Debt:
Total Long-term Debt	10,268	9,616
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	5,686	5,627
Deferred credits related to income taxes	105	105
Accumulated deferred investment tax credits	201	204
Employee benefit obligations	930	949
Asset retirement obligations, deferred	1,699	1,737
Other deferred credits and liabilities	395	347
Total deferred credits and other liabilities	9,016	8,969
Total Liabilities	21,647	21,880
Redeemable Preferred Stock	45	45
Preference Stock	221	221
Common Stockholders' Equity:
Common stock	398	398
Paid-in capital	6,504	6,275
Retained earnings (accumulated deficit)	4,002	4,061
Accumulated other comprehensive income (loss)	(15)	(15)
Total common stockholders' equity	10,889	10,719
Total Liabilities and Stockholders' Equity	32,802	32,865
Gulf Power [Member]
Current Assets:
Cash and cash equivalents	48	74
Receivables —
Customer accounts receivable	64	76
Unbilled revenues	52	54
Under recovered regulatory clause revenues	21	20
Income taxes receivable, current	0	27
Other accounts and notes receivable	5	9
Affiliated companies	8	1
Accumulated provision for uncollectible accounts	(1)	(1)
Fossil fuel stock, at average cost	93	108
Materials and supplies, at average cost	58	56
Other regulatory assets, current	90	90
Other current assets	18	22
Total current assets	456	536
Property, Plant, and Equipment:
In service	5,058	5,045
Less accumulated provision for depreciation	1,324	1,296
Plant in service, net of depreciation	3,734	3,749
Other utility plant, net	60	62
Construction work in progress	57	48
Total property, plant, and equipment	3,851	3,859
Other Property and Investments:
Total other property and investments	4	4
Deferred Charges and Other Assets:
Deferred charges related to income taxes	60	61
Other regulatory assets, deferred	420	427
Other deferred charges and assets	37	33
Total deferred charges and other assets	517	521
Total Assets	4,828	4,920
Current Liabilities:
Securities due within one year	110	110
Notes payable	56	142
Accounts payable —
Affiliated accounts payable	46	55
Other accounts payable	42	44
Customer deposits	36	36
Accrued taxes —
Accrued income taxes	10	4
Other accrued taxes	16	9
Accrued interest	20	9
Accrued compensation	8	25
Deferred capacity expense, current	22	22
Liabilities from risk management activities	54	49
Other regulatory liabilities, current	22	22
Other current liabilities	38	40
Total current liabilities	480	567
Long-term Debt:
Total Long-term Debt	1,193	1,193
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	899	893
Employee benefit obligations	128	129
Deferred capacity expense	136	141
Asset retirement obligations, deferred	114	113
Other cost of removal obligations	233	233
Other regulatory liabilities, deferred	45	47
Other deferred credits and liabilities	100	102
Total deferred credits and other liabilities	1,655	1,658
Total Liabilities	3,328	3,418
Preference Stock	147	147
Common Stockholders' Equity:
Common stock	503	503
Paid-in capital	569	567
Retained earnings (accumulated deficit)	284	285
Accumulated other comprehensive income (loss)	(3)	0
Total common stockholders' equity	1,353	1,355
Total Liabilities and Stockholders' Equity	4,828	4,920
Mississippi Power [Member]
Current Assets:
Cash and cash equivalents	58	98
Receivables —
Customer accounts receivable	23	26
Unbilled revenues	32	36
Income taxes receivable, current	0	20
Other accounts and notes receivable	6	10
Affiliated companies	7	20
Fossil fuel stock, at average cost	99	104
Materials and supplies, at average cost	76	75
Other regulatory assets, current	101	95
Prepaid income taxes	42	39
Other current assets	5	8
Total current assets	449	531
Property, Plant, and Equipment:
In service	4,905	4,886
Less accumulated provision for depreciation	1,287	1,262
Plant in service, net of depreciation	3,618	3,624
Construction work in progress	2,400	2,254
Total property, plant, and equipment	6,018	5,878
Other Property and Investments:
Total other property and investments	11	11
Deferred Charges and Other Assets:
Deferred charges related to income taxes	303	290
Other regulatory assets, deferred	520	525
Income taxes receivable, non-current	544	544
Other deferred charges and assets	71	61
Total deferred charges and other assets	1,438	1,420
Total Assets	7,916	7,840
Current Liabilities:
Securities due within one year	303	728
Notes payable	25	500
Accounts payable —
Affiliated accounts payable	82	85
Other accounts payable	108	135
Customer deposits	16	16
Accrued taxes —
Accrued income taxes	25	85
Accrued interest	21	18
Accrued compensation	10	26
Asset retirement obligations, current	39	22
Over recovered regulatory clause liabilities	106	96
Customer liability associated with Kemper refunds	22	73
Other current liabilities	55	52
Total current liabilities	812	1,836
Long-term Debt:
Long-term debt, affiliated	776	576
Long-term debt, non-affiliated	2,206	1,310
Total Long-term Debt	2,982	1,886
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	771	762
Deferred credits related to income taxes	8	8
Accumulated deferred investment tax credits	5	5
Employee benefit obligations	149	153
Asset retirement obligations, deferred	136	154
Unrecognized tax benefits	368	368
Other cost of removal obligations	167	165
Other regulatory liabilities, deferred	71	71
Other deferred credits and liabilities	41	40
Total deferred credits and other liabilities	1,716	1,726
Total Liabilities	5,510	5,448
Redeemable Preferred Stock	33	33
Common Stockholders' Equity:
Common stock	38	38
Paid-in capital	2,896	2,893
Retained earnings (accumulated deficit)	(555)	(566)
Accumulated other comprehensive income (loss)	(6)	(6)
Total common stockholders' equity	2,373	2,359
Total Liabilities and Stockholders' Equity	7,916	7,840
Southern Power [Member]
Current Assets:
Cash and cash equivalents	53	830
Receivables —
Customer accounts receivable	76	75
Other accounts and notes receivable	23	19
Affiliated companies	31	30
Fossil fuel stock, at average cost	14	16
Materials and supplies, at average cost	63	63
Prepaid income taxes	77	45
Prepaid expenses	23	23
Assets from risk management activities	6	7
Total current assets	366	1,108
Property, Plant, and Equipment:
In service	7,738	7,275
Less accumulated provision for depreciation	1,299	1,248
Plant in service, net of depreciation	6,439	6,027
Construction work in progress	1,535	1,137
Total property, plant, and equipment	7,974	7,164
Other Property and Investments:
Goodwill	2	2
Other intangible assets, net of amortization	316	317
Total other property and investments	318	319
Deferred Charges and Other Assets:
Prepaid long-term service agreements	184	166
Other deferred charges and assets -- affiliated	20	9
Other deferred charges and assets	137	139
Total deferred charges and other assets	341	314
Total Assets	8,999	8,905
Current Liabilities:
Securities due within one year	401	403
Notes payable	413	137
Accounts payable —
Affiliated accounts payable	62	66
Other accounts payable	347	327
Accrued taxes —
Accrued income taxes	9	198
Other accrued taxes	16	5
Accrued interest	25	23
Contingent consideration	21	36
Other current liabilities	49	44
Total current liabilities	1,343	1,239
Long-term Debt:
Total Long-term Debt	2,722	2,719
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	470	601
Accumulated deferred investment tax credits	1,025	889
Accrued income taxes, non-current	109	109
Asset retirement obligations, deferred	25	21
Deferred capacity revenues -- affiliated	6	17
Other deferred credits and liabilities	11	3
Total deferred credits and other liabilities	1,646	1,640
Total Liabilities	5,711	5,598
Redeemable Noncontrolling Interest	44	43
Common Stockholders' Equity:
Common stock	0	0
Paid-in capital	1,821	1,822
Retained earnings (accumulated deficit)	640	657
Accumulated other comprehensive income (loss)	5	4
Total common stockholders' equity	2,466	2,483
Noncontrolling Interests, Total	778	781
Total Stockholders' Equity	3,244	3,264
Total Liabilities and Stockholders' Equity	$ 8,999	$ 8,905

Condensed Consolidated Balance8

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
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	922,000,000	915,000,000
Treasury shares at cost	3,400,000	3,400,000
Alabama Power [Member]
Common stock, par value (in dollars per share)	$ 40	$ 40
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares outstanding	30,537,500	30,537,500
Georgia Power [Member]
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares outstanding	9,261,500	9,261,500
Gulf Power [Member]
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares outstanding	5,642,717	5,642,717
Mississippi Power [Member]
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	1,130,000	1,130,000
Common stock, shares outstanding	1,121,000	1,121,000
Southern Power [Member]
Other intangible assets, accumulated amortization	$ 13	$ 12
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000	1,000,000
Common stock, shares outstanding	1,000	1,000

Introduction

Introduction	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
INTRODUCTION	INTRODUCTION The condensed quarterly financial statements of each registrant included herein have been prepared by such registrant, without audit, pursuant to the rules and regulations of the SEC. The Condensed Balance Sheets as of December 31, 2015 have been derived from the audited financial statements of each registrant. In the opinion of each registrant's management, the information regarding such registrant furnished herein reflects all adjustments, which, except as otherwise disclosed, are of a normal recurring nature, necessary to present fairly the results of operations for the periods ended March 31, 2016 and 2015 . Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, although each registrant believes that the disclosures regarding such registrant are adequate to make the information presented not misleading. Disclosures which would substantially duplicate the disclosures in the Form 10-K and details which have not changed significantly in amount or composition since the filing of the Form 10-K are generally omitted from this Quarterly Report on Form 10-Q unless specifically required by GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K. Due to the seasonal variations in the demand for energy, operating results for the periods presented are not necessarily indicative of the operating results to be expected for the full year. Certain prior year data presented in the financial statements have been reclassified to conform to the current year presentation. These reclassifications had no impact on the results of operations, financial position, or cash flows of any registrant. Recently Issued Accounting Standards On February 25, 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 requires lessees to recognize on the balance sheet a lease liability and a right-of-use asset for all leases. ASU 2016-02 also changes the recognition, measurement, and presentation of expense associated with leases and provides clarification regarding the identification of certain components of contracts that would represent a lease. The accounting required by lessors is relatively unchanged and there is no change to the accounting for existing leveraged leases. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The registrants are currently evaluating the new standard and have not yet determined its ultimate impact; however, adoption of ASU 2016-02 is expected to have a significant impact on Southern Company and the traditional operating companies' balance sheets. On March 30, 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). ASU 2016-09 changes the accounting for income taxes and the cash flow presentation for share-based payment award transactions. Most significantly, entities are required to recognize all excess tax benefits and deficiencies related to the exercise or vesting of stock compensation as income tax expense or benefit in the income statement. Southern Company and the traditional operating companies currently recognize any excess tax benefits and deficiencies related to the exercise and vesting of stock compensation in additional paid-in capital. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, with early adoption permitted. Southern Company and the traditional operating companies are currently evaluating the new standard and have not yet determined its ultimate impact.

Contingencies and Regulatory Ma

Contingencies and Regulatory Matters	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
CONTINGENCIES AND REGULATORY MATTERS	CONTINGENCIES AND REGULATORY MATTERS See Note 3 to the financial statements of the registrants in Item 8 of the Form 10-K for information relating to various lawsuits, other contingencies, and regulatory matters. General Litigation Matters Each registrant is subject to certain claims and legal actions arising in the ordinary course of business. In addition, business activities of Southern Company's subsidiaries are subject to extensive governmental regulation related to public health and the environment, such as regulation of air emissions and water discharges. Litigation over environmental issues and claims of various types, including property damage, personal injury, common law nuisance, and citizen enforcement of environmental requirements such as air quality and water standards, has occurred throughout the U.S. This litigation has included claims for damages alleged to have been caused by CO 2 and other emissions, CCR, and alleged exposure to hazardous materials, and/or requests for injunctive relief in connection with such matters. The ultimate outcome of such pending or potential litigation against each registrant and any subsidiaries cannot be predicted at this time; however, for current proceedings not specifically reported herein or in Note 3 to the financial statements of each registrant in Item 8 of the Form 10-K, management does not anticipate that the ultimate liabilities, if any, arising from such current proceedings would have a material effect on such registrant's financial statements. Environmental Remediation The Southern Company system must comply with environmental laws and regulations that cover the handling and disposal of waste and releases of hazardous substances. Under these various laws and regulations, the Southern Company system could incur substantial costs to clean up affected sites. The traditional 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 March 31, 2016 was $28 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. The ultimate outcome of these matters will depend upon the success of defenses asserted, the ultimate number of PRPs participating in the cleanup, and numerous other factors and cannot be determined at this time; however, as a result of Georgia Power's regulatory treatment for environmental remediation expenses, these matters are not expected to have a material impact on Southern Company's or Georgia Power's financial statements. Gulf Power's environmental remediation liability includes estimated costs of environmental remediation projects of approximately $46 million as of March 31, 2016 . These estimated costs primarily relate to site closure criteria by the Florida Department of Environmental Protection (FDEP) for potential impacts to soil and groundwater from herbicide applications at Gulf Power substations. The schedule for completion of the remediation projects is subject to FDEP approval. The projects have been approved by the Florida PSC for recovery through Gulf Power's environmental cost recovery clause; therefore, these liabilities have no impact on net income. The final outcome of these matters cannot be determined at this time. However, based on the currently known conditions at these sites and the nature and extent of activities relating to these sites, management of Southern Company and Gulf Power does not believe that additional liabilities, if any, at these sites would be material to their respective financial statements . 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. On March 31, 2016, Mississippi Power filed a request with the FERC for an increase in wholesale base revenues as agreed upon in the settlement agreement reached with its wholesale customers under the Municipal and Rural Associations (MRA) cost-based electric tariff. The settlement agreement provides that base rates under the MRA cost-based electric tariff will increase approximately $7 million annually, with revised rates effective for services rendered beginning May 1, 2016. The increase is primarily due to the Plant Daniel Units 1 and 2 scrubbers, which were placed in service in November 2015. Additionally, under the settlement agreement, the tariff customers agreed in principle to similar regulatory treatment for tariff ratemaking as the treatment approved for retail ratemaking under the Mississippi PSC order (In-Service Asset Rate Order). The Kemper IGCC regulatory treatment primarily includes (i) recovery of only the Kemper IGCC assets currently operational and providing service to customers and other related costs and (ii) removing all of the Kemper IGCC CWIP with a corresponding increase in accrual of AFUDC effective May 1, 2016. If approved by the FERC, the amount of base rate revenues to be recognized in 2016 is expected to be approximately $5 million . The additional resulting AFUDC is estimated to be approximately $6 million . The ultimate outcome of this matter cannot be determined at this time. Fuel Cost Recovery Mississippi Power has a wholesale MRA and a Market Based (MB) fuel cost recovery factor. At March 31, 2016 , the amount of over-recovered wholesale MRA fuel costs included in the balance sheets was $25 million compared to $24 million at December 31, 2015 . See Note 3 to the financial statements of Mississippi Power under "FERC Matters – Fuel Cost Recovery" in Item 8 of the Form 10-K for additional information. Market-Based Rate Authority The traditional 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 in 2014, which included continued reliance on the energy auction as tailored mitigation. In April 2015, the FERC issued an order finding that the traditional 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. 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 in May 2015 and in June 2015 filed their response with the FERC. The ultimate outcome of this matter cannot be determined at this time. Retail Regulatory Matters Alabama Power See Note 3 to the financial statements of Southern Company and Alabama Power under "Retail Regulatory Matters – Alabama Power" and "Retail Regulatory Matters," respectively, in Item 8 of the Form 10-K for additional information regarding Alabama Power's recovery of retail costs through various regulatory clauses and accounting orders. The balance of each regulatory clause recovery on the balance sheet follows: Regulatory Clause Balance Sheet Line Item March 31, 2016 December 31, 2015 (in millions) Rate CNP Compliance Under recovered regulatory clause revenues, current $ 22 $ 43 Rate CNP PPA Deferred under recovered regulatory clause revenues 105 99 Retail Energy Cost Recovery Other regulatory liabilities, current 173 238 Deferred over recovered regulatory clause revenues 64 — Natural Disaster Reserve Other regulatory liabilities, deferred 74 75 Georgia Power Rate Plans See Note 3 to the financial statements of Southern Company and Georgia Power under "Retail Regulatory Matters – Georgia Power – Rate Plans" and "Retail Regulatory Matters – Rate Plans," respectively, in Item 8 of the Form 10-K for additional information. Georgia Power's revenues from regulated retail operations are collected through various rate mechanisms subject to the oversight of the Georgia PSC. Georgia Power currently recovers its costs from the regulated retail business through the 2013 ARP, which includes traditional base tariff rates, Demand-Side Management tariffs, Environmental Compliance Cost Recovery tariffs, and Municipal Franchise Fee tariffs. In addition, financing costs related to the construction of Plant Vogtle Units 3 and 4 are being collected through the NCCR tariff and fuel costs are collected through separate fuel cost recovery tariffs. See "Fuel Cost Recovery" below and Note 3 to the financial statements of Georgia Power under "Retail Regulatory Matters – Nuclear Construction" and Southern Company under "Retail Regulatory Matters – Georgia Power – Fuel Cost Recovery" and " – Nuclear Construction" in Item 8 of the Form 10-K for additional information regarding fuel cost recovery and the NCCR tariff, respectively. Pursuant to the terms and conditions of a settlement agreement related to Southern Company's proposed acquisition of AGL Resources approved by the Georgia PSC on April 14, 2016, Georgia Power's 2013 ARP will continue in effect until December 31, 2019, and Georgia Power will be required to file its next base rate case by July 1, 2019. Furthermore, through December 31, 2019, Georgia Power and Atlanta Gas Light Company (collectively, Utilities) will retain the merger savings, net of transition costs, as defined in the settlement agreement; through December 31, 2022, net merger savings will be shared on a 60 / 40 basis between customers and the Utilities; thereafter, all merger savings will be retained by customers. See Note (I) under "Southern Company – Proposed Merger with AGL Resources" for additional information regarding the Merger. 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 March 31, 2016 and December 31, 2015 , Georgia Power's over recovered fuel balance totaled $177 million and $116 million , respectively, and is included in current liabilities and other deferred liabilities on Southern Company's and Georgia Power's Condensed Balance Sheets herein. On April 14, 2016, Georgia Power filed a request with the Georgia PSC to decrease fuel rates by 15% effective June 1, 2016, which is expected to reduce annual billings by approximately $313 million . Georgia Power is currently scheduled to file its next fuel case by February 28, 2017. 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, the NCCR tariff, the Vogtle Construction Litigation (as defined below), and the Contractor Settlement Agreement (as defined below). In 2008, Georgia Power, acting for itself and as agent for the Vogtle Owners, entered into an agreement with the Contractor, pursuant to which the Contractor agreed to design, engineer, procure, construct, and test Plant Vogtle Units 3 and 4 (Vogtle 3 and 4 Agreement). Under the terms of the Vogtle 3 and 4 Agreement, the Vogtle Owners agreed to pay a purchase price 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% . On December 31, 2015, Westinghouse acquired Stone & Webster, Inc. from Chicago Bridge & Iron Company, N.V. (CB&I) and changed the name of Stone & Webster, Inc. to WECTEC Global Project Services Inc. (WECTEC). Certain obligations of Westinghouse and WECTEC under the Vogtle 3 and 4 Agreement were originally guaranteed by Toshiba Corporation (Westinghouse's parent company) and The Shaw Group Inc. (which is now a subsidiary of CB&I), respectively. On March 9, 2016, in connection with Westinghouse's acquisition of WECTEC and pursuant to the settlement agreement described below, the guarantee of The Shaw Group Inc. was terminated. The guarantee of Toshiba Corporation remains in place. In the event of certain credit rating downgrades of any Vogtle Owner, such Vogtle Owner will be required to provide a letter of credit or other credit enhancement. Additionally, as a result of credit rating downgrades of Toshiba Corporation, Westinghouse provided the Vogtle Owners with letters of credit in an aggregate amount of $920 million in accordance with, and subject to adjustment under, the terms of the Vogtle 3 and 4 Agreement. The Vogtle Owners may terminate the Vogtle 3 and 4 Agreement at any time for their convenience, provided that the Vogtle Owners will be required to pay certain termination costs. The Contractor may terminate the Vogtle 3 and 4 Agreement under certain circumstances, including certain Vogtle Owner suspension or delays of work, action by a governmental authority to permanently stop work, certain breaches of the Vogtle 3 and 4 Agreement by the Vogtle Owners, Vogtle Owner insolvency, and certain other events. In 2009, the Georgia PSC voted to certify construction of Plant Vogtle Units 3 and 4. Georgia Power is required to file semi-annual VCM reports with the Georgia PSC by February 28 and August 31 each year. If the projected construction capital costs to be borne by Georgia Power increase by 5% above the certified cost or the projected in-service dates are significantly extended, Georgia Power is required to seek an amendment to the Plant Vogtle Units 3 and 4 certificate from the Georgia PSC. In February 2013, Georgia Power requested an amendment to the certificate to increase the estimated in-service capital cost of Plant Vogtle Units 3 and 4 from $4.4 billion to $4.8 billion and to extend the estimated in-service dates to the fourth quarter 2017 (from April 2016) and the fourth quarter 2018 (from April 2017) for Plant Vogtle Units 3 and 4, respectively. In October 2013, the Georgia PSC approved a stipulation (2013 Stipulation) between Georgia Power and the Georgia PSC Staff (Staff) to waive the requirement to amend the Plant Vogtle Units 3 and 4 certificate until the completion of Plant Vogtle Unit 3 or earlier if deemed appropriate by the Georgia PSC and Georgia Power. On April 15, 2015, the Georgia PSC issued a procedural order in connection with the twelfth VCM report, which included a requested amendment (Requested Amendment) to the Plant Vogtle Units 3 and 4 certificate to reflect the Contractor's revised forecast for completion of Plant Vogtle Units 3 and 4 (second quarter of 2019 and second quarter of 2020, respectively) as well as additional estimated Vogtle Owner's costs, of approximately $10 million per month, including property taxes, oversight costs, compliance costs, and other operational readiness costs to include the estimated Vogtle Owner's costs associated with the proposed 18 -month Contractor delay and to increase the estimated total in-service capital cost of Plant Vogtle Units 3 and 4 to $5.0 billion . Pursuant to the Georgia PSC's procedural order, the Georgia PSC deemed the Requested Amendment unnecessary and withdrawn until the completion of construction of Plant Vogtle Unit 3 consistent with the 2013 Stipulation. The Georgia PSC recognized that the certified cost and the 2013 Stipulation do not constitute a cost recovery cap. In accordance with the Georgia Integrated Resource Planning Act, any costs incurred by Georgia Power in excess of the certified amount will be included in rate base, provided Georgia Power shows the costs to be reasonable and prudent. Financing costs up to the certified amount will be collected through the NCCR tariff until the units are placed in service and contemplated in a general base rate case, while financing costs on any construction-related costs in excess of the $4.4 billion certified amount are expected to be recovered through AFUDC. On December 31, 2015, Westinghouse and the Vogtle Owners entered into a definitive settlement agreement (Contractor Settlement Agreement) to resolve disputes between the Vogtle Owners and the Contractor under the Vogtle 3 and 4 Agreement, including litigation that was pending in the U.S. District Court for the Southern District of Georgia (Vogtle Construction Litigation). Effective December 31, 2015, Georgia Power, acting for itself and as agent for the other Vogtle Owners, and the Contractor entered into an amendment to the Vogtle 3 and 4 Agreement to implement the Contractor Settlement Agreement. The Contractor Settlement Agreement and the related amendment to the Vogtle 3 and 4 Agreement (i) restrict the Contractor's ability to seek further increases in the contract price by clarifying and limiting the circumstances that constitute nuclear regulatory changes in law; (ii) provide for enhanced dispute resolution procedures; (iii) revise the guaranteed substantial completion dates to match the current estimated in-service dates of June 30, 2019 for Unit 3 and June 30, 2020 for Unit 4; (iv) provide that delay liquidated damages will commence from the current estimated nuclear fuel loading date for each unit, which is December 31, 2018 for Unit 3 and December 31, 2019 for Unit 4; and (v) provide that Georgia Power, based on its ownership interest, will pay to the Contractor and capitalize to the project cost approximately $350 million , of which approximately $241 million had been paid as of March 31, 2016. In addition, the Contractor Settlement Agreement provides for the resolution of other open existing items relating to the scope of the project under the Vogtle 3 and 4 Agreement, including cyber security, for which costs were reflected in Georgia Power's previously disclosed in-service cost estimate. Further, as part of the settlement and Westinghouse's acquisition of WECTEC: (i) Westinghouse engaged Fluor Enterprises, Inc., a subsidiary of Fluor Corporation, as a new construction subcontractor; and (ii) the Vogtle Owners, CB&I, and The Shaw Group Inc. entered into mutual releases of any and all claims arising out of events or circumstances in connection with the construction of Plant Vogtle Units 3 and 4 that occurred on or before the date of the Contractor Settlement Agreement. On January 5, 2016, the Vogtle Construction Litigation was dismissed with prejudice. On January 21, 2016, Georgia Power submitted the Contractor Settlement Agreement and the related amendment to the Vogtle 3 and 4 Agreement to the Georgia PSC for its review. In accordance with the Georgia PSC's subsequent order, on April 5, 2016, Georgia Power filed supplemental information in support of the Contractor Settlement Agreement and Georgia Power's position that all construction costs to date have been prudently incurred and that the current estimated in-service capital cost and schedule are reasonable. The Staff will conduct a review of all costs incurred related to Plant Vogtle Units 3 and 4, the schedule for completion of Plant Vogtle Units 3 and 4, and the Contractor Settlement Agreement and the Staff is authorized to engage in related settlement discussions with Georgia Power and any intervenors. The order provides that the Staff is required to report to the Georgia PSC by October 19, 2016 with respect to the status of its review and any settlement-related negotiations. If a settlement with the Staff is reached with respect to costs of Plant Vogtle Units 3 and 4, the Georgia PSC will then conduct a hearing to consider whether to approve that settlement. If a settlement with the Staff is not reached, the Georgia PSC will determine how to proceed, including (i) modifying the 2013 Stipulation, (ii) directing Georgia Power to file a request for an amendment to the certificate for Plant Vogtle Units 3 and 4, (iii) issuing a scheduling order to address remaining disputed issues, or (iv) taking any other option within its authority. The Georgia PSC has approved thirteen VCM reports covering the periods through June 30, 2015, including construction capital costs incurred, which through that date totaled $3.1 billion . On February 26, 2016, Georgia Power filed its fourteenth VCM report with the Georgia PSC covering the period from July 1 through December 31, 2015. The fourteenth VCM report does not include a requested amendment to the certified cost of Plant Vogtle Units 3 and 4. Georgia Power is requesting approval of $160 million of construction capital costs incurred during that period. Georgia Power anticipates to incur average financing costs of approximately $27 million per month from January 2016 until Plant Vogtle Units 3 and 4 are placed in service. The updated in-service capital cost forecast is $5.44 billion and includes costs related to the Contractor Settlement Agreement. Estimated financing costs during the construction period total approximately $2.4 billion . Georgia Power's CWIP balance for Plant Vogtle Units 3 and 4 was approximately $3.7 billion as of March 31, 2016 . 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. Processes are in place that are designed to assure compliance with the requirements specified in the Westinghouse Design Control Document and the combined construction and operating licenses, including inspections by Southern Nuclear and the NRC that occur throughout construction. As a result of such compliance processes, certain license amendment requests have been filed and approved or are pending before the NRC. Various design and other licensing-based compliance issues may arise as construction proceeds, which may result in additional license amendments or require other resolution. If any license amendment requests or other licensing-based compliance issues are not resolved in a timely manner, there may be delays in the project schedule that could result in increased costs either to the Vogtle Owners or the Contractor or to both. As construction continues, the risk remains that challenges with Contractor performance including fabrication, assembly, delivery, and installation of the shield building and structural modules, delays in the receipt of the remaining permits necessary for the operation of Plant Vogtle Units 3 and 4, or other issues could arise and may further impact project schedule and cost. In addition, the IRS allocated production tax credits to each of Plant Vogtle Units 3 and 4, which require the applicable unit to be placed in service before 2021. Future claims by the Contractor or Georgia Power (on behalf of the Vogtle Owners) could arise throughout construction. These claims may be resolved through formal and informal dispute resolution procedures under the Vogtle 3 and 4 Agreement and, under the enhanced dispute resolution procedures, may be resolved through litigation after the completion of nuclear fuel load for both units. The ultimate outcome of these matters cannot be determined at this time. Gulf Power Retail Base Rate Case See Note 3 to the financial statements of Gulf Power under "Retail Regulatory Matters – Retail Base Rate Case" in Item 8 of the Form 10-K for additional information. In 2013, the Florida PSC approved a settlement agreement providing that Gulf Power may reduce depreciation and record a regulatory asset up to $62.5 million between January 2014 and June 2017. In any given month, such depreciation reduction may not exceed the amount necessary for the retail ROE, as reported to the Florida PSC monthly, to reach the midpoint of the authorized retail ROE range then in effect. For 2014, 2015 , and the first three months of 2016 , Gulf Power recognized reductions in depreciation of $8.4 million , $20.1 million , and $5.6 million , respectively. Cost Recovery Clauses See Note 3 to the financial statements of Gulf Power under "Retail Regulatory Matters – Cost Recovery Clauses" in Item 8 of the Form 10-K for additional information regarding Gulf Power's recovery of retail costs through various regulatory clauses and accounting orders. Gulf Power has four regulatory clauses which are approved by the Florida PSC. The balance of each regulatory clause recovery on the balance sheet follows: Regulatory Clause Balance Sheet Location March 31, 2016 December 31, 2015 (in millions) Fuel Cost Recovery Other regulatory liabilities, current $ 20 $ 18 Purchased Power Capacity Recovery Under recovered regulatory clause revenues 4 1 Environmental Cost Recovery Under recovered regulatory clause revenues 17 19 Energy Conservation Cost Recovery Other regulatory liabilities, current 2 4 Mississippi Power Performance Evaluation Plan See Note 3 to the financial statements of Mississippi Power under "Retail Regulatory Matters – Performance Evaluation Plan" in Item 8 of the Form 10-K for additional information regarding Mississippi Power's base rates. On April 1, 2016, Mississippi Power submitted its annual PEP lookback filing for 2015, which reflected the need for a $5 million surcharge to be recovered from customers. The filing has been suspended for review by the Mississippi PSC. The ultimate outcome of this matter cannot be determined at this time. Fuel Cost Recovery 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 information regarding Mississippi Power's retail fuel cost recovery. At March 31, 2016 , the amount of over-recovered retail fuel costs included on Mississippi Power's Condensed Balance Sheet herein was $80 million compared to over-recovered retail fuel costs of $71 million at December 31, 2015. The Mississippi PSC conditionally approved a decrease of $120 million annually in fuel cost recovery rates on January 5, 2016, effective with the first billing cycle of February. As required by the order, on February 1, 2016, Mississippi Power submitted updated natural gas price forecasts and resulting fuel factors to the Mississippi PSC. If approved by the Mississippi PSC, the updated forecast would decrease fuel cost recovery rates by an additional $36 million annually. The ultimate outcome of this matter cannot be determined at this time. Integrated Coal Gasification Combined Cycle 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 for information regarding Mississippi Power's construction of the Kemper IGCC. Kemper IGCC Overview Construction of Mississippi Power's Kemper IGCC is nearing completion and start-up activities will continue until the Kemper IGCC is placed in service. The Kemper IGCC will utilize an IGCC technology with an output capacity of 582 MWs. The Kemper IGCC will be fueled by locally mined lignite (an abundant, lower heating value coal) from a mine owned by Mississippi Power and situated adjacent to the Kemper IGCC. The mine, operated by North American Coal Corporation, started commercial operation in 2013. In connection with the Kemper IGCC, Mississippi Power constructed and plans to operate approximately 61 miles of CO 2 pipeline infrastructure for the planned transport of captured CO 2 for use in enhanced oil recovery. Kemper IGCC Schedule and Cost Estimate In 2012, the Mississippi PSC issued the 2012 MPSC CPCN Order, a detailed order confirming the CPCN originally approved by the Mississippi PSC in 2010 authorizing the acquisition, construction, and operation of the Kemper IGCC. The certificated cost estimate of the Kemper IGCC included in the 2012 MPSC CPCN Order was $2.4 billion , net of $245 million of grants awarded to the Kemper IGCC project by the DOE under the Clean Coal Power Initiative Round 2 (Initial DOE Grants) and excluding the cost of the lignite mine and equipment, the cost of the CO 2 pipeline facilities, and AFUDC related to the Kemper IGCC. The 2012 MPSC CPCN Order approved a construction cost cap of up to $2.88 billion , with recovery of prudently-incurred costs subject to approval by the Mississippi PSC. The Kemper IGCC was originally projected to be placed in service in May 2014. Mississippi Power placed the combined cycle and the associated common facilities portion of the Kemper IGCC in service using natural gas in August 2014 and currently expects to place the remainder of the Kemper IGCC, including the gasifier and the gas clean-up facilities, in service during the third quarter 2016. Recovery of the costs subject to the cost cap and the cost of the lignite mine and equipment, the cost of the CO 2 pipeline facilities, AFUDC, and certain general exceptions, including change of law, force majeure, and beneficial capital (which exists when Mississippi Power demonstrates that the purpose and effect of the construction cost increase is to produce efficiencies that will result in a neutral or favorable effect on customers relative to the original proposal for the CPCN) (Cost Cap Exceptions) remains subject to review and approval by the Mississippi PSC. Mississippi Power's Kemper IGCC 2010 project estimate, current cost estimate (which includes the impacts of the Mississippi Supreme Court's (Court) decision discussed herein under "Rate Recovery of Kemper IGCC Costs – 2013 MPSC Rate Order"), and actual costs incurred as of March 31, 2016 , are as follows: Cost Category 2010 Project Estimate (f) Current Cost Estimate (a) Actual Costs (in billions) Plant Subject to Cost Cap (b)(g) $ 2.40 $ 5.35 $ 4.99 Lignite Mine and Equipment 0.21 0.23 0.23 CO 2 Pipeline Facilities 0.14 0.11 0.12 AFUDC (c) 0.17 0.71 0.62 Combined Cycle and Related Assets Placed in (d)(g) — 0.02

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS As of March 31, 2016 , assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows: Fair Value Measurements Using As of March 31, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Southern Company Assets: Energy-related derivatives $ — $ 12 $ — $ — $ 12 Interest rate derivatives — 33 — — 33 Nuclear decommissioning trusts (a) 624 898 — 16 1,538 Cash equivalents 503 — — — 503 Other investments 9 — 1 — 10 Total $ 1,136 $ 943 $ 1 $ 16 $ 2,096 Liabilities: Energy-related derivatives $ — $ 201 $ — $ — $ 201 Interest rate derivatives — 193 — — 193 Total $ — $ 394 $ — $ — $ 394 Alabama Power Assets: Energy-related derivatives $ — $ 3 $ — $ — $ 3 Nuclear decommissioning trusts (b) Domestic equity 365 67 — — 432 Foreign equity 46 48 — — 94 U.S. Treasury and government agency securities — 25 — — 25 Corporate bonds 11 137 — — 148 Mortgage and asset backed securities — 21 — — 21 Private Equity — — — 16 16 Other — 9 — — 9 Cash equivalents 321 — — — 321 Total $ 743 $ 310 $ — $ 16 $ 1,069 Liabilities: Energy-related derivatives $ — $ 49 $ — $ — $ 49 Fair Value Measurements Using As of March 31, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Georgia Power Assets: Energy-related derivatives $ — $ 4 $ — $ — $ 4 Interest rate derivatives — 14 — — 14 Nuclear decommissioning trusts (b) (c) Domestic equity 180 1 — — 181 Foreign equity — 115 — — 115 U.S. Treasury and government agency securities — 111 — — 111 Municipal bonds — 66 — — 66 Corporate bonds — 146 — — 146 Mortgage and asset backed securities — 145 — — 145 Other 22 7 — — 29 Cash equivalents 57 — — — 57 Total $ 259 $ 609 $ — $ — $ 868 Liabilities: Energy-related derivatives $ — $ 11 $ — $ — $ 11 Gulf Power Assets: Cash equivalents $ 20 $ — $ — $ — $ 20 Liabilities: Energy-related derivatives $ — $ 94 $ — $ — $ 94 Interest rate derivatives — 5 — — 5 Total $ — $ 99 $ — $ — $ 99 Mississippi Power Assets: Cash equivalents $ 24 $ — $ — $ — $ 24 Liabilities: Energy-related derivatives $ — $ 44 $ — $ — $ 44 Southern Power Assets: Energy-related derivatives $ — $ 5 $ — $ — $ 5 Interest rate derivatives — 1 — — 1 Cash equivalents 39 — — — 39 Total $ 39 $ 6 $ — $ — $ 45 Liabilities: Energy-related derivatives $ — $ 3 $ — $ — $ 3 (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 March 31, 2016 , approximately $58 million of the fair market value of Georgia Power's nuclear decommissioning trust funds' securities were on loan to creditors under the funds' managers' securities lending program. Southern Company, Alabama Power, and Georgia Power continue to elect the option to fair value investment securities held in the nuclear decommissioning trust funds. For the three months ended March 31, 2016 and March 31, 2015 , the change in fair value of the funds, including reinvested interest and dividends and excluding the funds' expenses, increased by $20 million and $33 million , respectively, at Southern Company. For the three months ended March 31, 2016 and March 31, 2015 , Alabama Power recorded an increase in fair value of $11 million and $15 million , respectively, as an increase in regulatory liabilities related to its asset retirement obligations. For the three months ended March 31, 2016 and March 31, 2015 , Georgia Power recorded an increase in fair value of $9 million and $18 million , respectively, as a reduction of its regulatory asset related to its asset retirement obligations. 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 products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflect the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and occasionally, implied volatility of interest rate options. The interest rate derivatives are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note (H) for additional information on how these derivatives are used. The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. For fair value measurements of the investments within the nuclear decommissioning trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available. See Note 1 to the financial statements of Southern Company, Alabama Power, and Georgia Power under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information. "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 March 31, 2016 , the fair value measurements of private equity investments held in the nuclear decommissioning trust that are calculated at net asset value per share (or its equivalent) as a practical expedient, as well as the nature and risks of those investments, were as follows: As of March 31, 2016: Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period (in millions) Southern Company $ 16 $ 29 Not Applicable Not Applicable Alabama Power $ 16 $ 29 Not Applicable Not Applicable Private equity funds include a fund-of-funds that invests in high-quality private equity funds across several market sectors, a fund that invests in real estate assets, and a fund that acquires companies to create resale value. Private equity funds do not have redemption rights. Distributions from these funds will be received as the underlying investments in the funds are liquidated. Liquidations are expected to occur at various times over the next ten years . As of March 31, 2016 , other financial instruments for which the carrying amount did not equal fair value were as follows: Carrying Amount Fair Value (in millions) Long-term debt, including securities due within one year: Southern Company $ 28,341 $ 29,827 Alabama Power $ 7,089 $ 7,688 Georgia Power $ 10,549 $ 11,400 Gulf Power $ 1,303 $ 1,366 Mississippi Power $ 3,209 $ 2,938 Southern Power $ 3,123 $ 3,171 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	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY Earnings per Share For Southern Company, the only difference in computing basic and diluted earnings per share is attributable to awards outstanding under the stock option and performance share plans. See Note 8 to the financial statements of Southern Company in Item 8 of the Form 10-K for information on the stock option and performance share plans. The effect of both stock options and performance share award units was determined using the treasury stock method. Shares used to compute diluted earnings per share were as follows: Three Months Ended March 31, 2016 Three Months Ended March 31, 2015 (in millions) As reported shares 916 910 Effect of options and performance share award units 6 5 Diluted shares 922 915 Stock options and performance share award units that were not included in the diluted earnings per share calculation because they were anti-dilutive were immaterial for the three months ended March 31, 2016 and 2015 . Changes in Stockholders' Equity The following table presents year-to-date changes in stockholders' equity of Southern Company: Number of Common Shares Common Preferred and Preference Stock of Subsidiaries Total Issued Treasury Noncontrolling Interests (*) (in thousands) (in millions) Balance at December 31, 2015 915,073 (3,352 ) $ 20,592 $ 609 $ 781 $ 21,982 Consolidated net income attributable to Southern Company — — 485 — — 485 Other comprehensive income (loss) — — (114 ) — — (114 ) Stock issued 6,572 — 270 — — 270 Stock-based compensation — — 60 — — 60 Cash dividends on common stock — — (497 ) — — (497 ) Contributions from noncontrolling interests — — — — 129 129 Distributions to noncontrolling interests — — — — (4 ) (4 ) Purchase of membership interests from noncontrolling interests — — — — (129 ) (129 ) Net income attributable to noncontrolling interests — — — — 1 1 Other — (35 ) 1 — — 1 Balance at March 31, 2016 921,645 (3,387 ) $ 20,797 $ 609 $ 778 $ 22,184 Balance at December 31, 2014 908,502 (725 ) $ 19,949 $ 756 $ 221 $ 20,926 Consolidated net income attributable to Southern Company — — 508 — — 508 Other comprehensive income (loss) — — (15 ) — — (15 ) Stock issued 3,094 — 112 — — 112 Stock-based compensation — — 53 — — 53 Stock repurchased, at cost — (2,599 ) (115 ) — — (115 ) Cash dividends on common stock — — (478 ) — — (478 ) Other — (11 ) 3 — — 3 Balance at March 31, 2015 911,596 (3,335 ) $ 20,017 $ 756 $ 221 $ 20,994 (*) Primarily related to Southern Power Company.

Financing

Financing	3 Months Ended
	Mar. 31, 2016
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' pollution control revenue bonds. The amount of variable rate pollution control revenue bonds outstanding requiring liquidity support as of March 31, 2016 was approximately $1.8 billion (comprised of approximately $810 million at Alabama Power, $868 million at Georgia Power, $82 million at Gulf Power, and $40 million at Mississippi Power). In addition, at March 31, 2016 , the traditional operating companies had approximately $269 million (comprised of approximately $167 million at Alabama Power, $69 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. 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 March 31, 2016 : Expires Executable Term Loans Due Within One Year Company 2016 2017 2018 2020 Total Unused One Year Two Years Term Out No Term Out (in millions) (in millions) (in millions) Southern Company (a) $ — $ — $ 1,000 $1,250 $ 2,250 $ 2,250 $ — $ — $ — $ — Alabama Power 40 — 500 800 1,340 1,340 — — — 40 Georgia Power — — — 1,750 1,750 1,732 — — — — Gulf Power 75 40 165 — 280 280 45 — 45 40 Mississippi Power 205 — — — 205 180 30 15 45 160 Southern Power Company (b) — — — 600 600 560 — — — — Other 70 — — — 70 70 20 — 20 50 Total $ 390 $ 40 $ 1,665 $4,400 $ 6,495 $ 6,412 $ 95 $ 15 $ 110 $ 290 (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) Excluding its subsidiaries. See "Project Credit Facilities" below and Note (I) under "Southern Power" for additional information. 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 fund the cash consideration for the Merger using a mix of debt and equity. Southern Company finances its capital needs on a portfolio basis and expects to issue a minimum of $8.0 billion in debt prior to closing the Merger and a minimum of $1.2 billion in equity during 2016. This capital is expected to provide funding for the Merger, the proposed acquisition of PowerSecure International, Inc. (PowerSecure), and Southern Power and other Southern Company system capital projects. Total capital raised in 2016 may increase due to cash needed at the closing of the Merger, settlement of hedges, and incremental investment opportunities, including additional Southern Power projects in excess of its current capital plans. 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. As of March 31, 2016, Southern Company had no outstanding loans under the Bridge Agreement. See Note (I) under "Southern Company – Proposed Merger with AGL Resources" for additional information regarding the Merger. See Note 6 to the financial statements of Southern Company under "Bank Credit Arrangements" in Item 8 of the Form 10-K for additional information regarding the Bridge Agreement. Southern Power Project Credit Facilities In connection with the construction of solar facilities by RE Tranquillity LLC, RE Roserock LLC, and RE Garland Holdings LLC, indirect subsidiaries of Southern Power, each subsidiary entered into separate credit agreements (Project Credit Facilities), which are non-recourse to Southern Power (other than the subsidiary party to the agreement). Each Project Credit Facility provides (a) a senior secured construction loan credit facility, (b) a senior secured bridge loan facility, and (c) a senior secured letter of credit facility that is secured by the membership interests of the respective project company. Proceeds from the Project Credit Facilities are being used to finance project costs related to the respective solar facilities currently under construction. Each Project Credit Facility is secured by the assets of the applicable project subsidiary and membership interests of the applicable project subsidiary. The table below summarizes each Project Credit Facility as of March 31, 2016 . Project Maturity Date Construction Loan Facility Bridge Loan Facility Total Total Undrawn Letter of Credit Facility Total Undrawn (in millions) Tranquillity Earlier of COD or December 31, 2016 $ 86 $ 172 $ 258 $ 52 $ 77 $ 26 Roserock Earlier of COD or November 30, 2016 63 180 243 121 23 16 Garland Earlier of COD or November 30, 2016 86 308 394 309 49 32 Total $ 235 $ 660 $ 895 $ 482 $ 149 $ 74 The Project Credit Facilities had total amounts outstanding as of March 31, 2016 of $413 million at a weighted average interest rate of 1.99% . For the three months ended March 31, 2016, these credit agreements had a maximum amount outstanding of $413 million , and an average amount outstanding of $260 million at a weighted average interest rate of 1.99% . Financing Activities The following table outlines the long-term debt financing activities for Southern Company and its subsidiaries for the first three months of 2016 : Company (a) Senior Note Issuances Senior Note Maturities and Redemptions Revenue Other Long-Term Debt Issuances Other Long-Term Debt Redemptions and Maturities (b) (in millions) Alabama Power $ 400 $ 200 $ — $ 45 $ — Georgia Power 650 250 4 — 1 Mississippi Power — — — 1,100 426 Southern Power — — — 2 3 Other — — — — 4 Elimination (c) — — — (200 ) — Total $ 1,050 $ 450 $ 4 $ 947 $ 434 (a) Southern Company and Gulf Power did not issue or redeem any long-term debt during the first three months of 2016. (b) Includes reductions in capital lease obligations resulting from cash payments under capital leases. (c) Intercompany loans from Southern Company to Mississippi Power eliminated in Southern Company's Consolidated Financial Statements. Alabama Power In January 2016, Alabama Power issued $400 million aggregate principal amount of Series 2016A 4.30% Senior Notes due January 2, 2046. The proceeds were used to repay at maturity $200 million aggregate principal amount of Alabama Power's Series FF 5.20% Senior Notes due January 15, 2016 and for general corporate purposes, including Alabama Power's continuous construction program. In March 2016, Alabama Power entered into three bank term loan agreements with maturity dates of March 2021, in an aggregate principal amount of $45 million , one of which bears interest at 2.38% per annum and two of which bear interest based on three-month LIBOR. Georgia Power In March 2016, Georgia Power issued $325 million aggregate principal amount of Series 2016A 3.25% Senior Notes due April 1, 2026 and $325 million aggregate principal amount of Series 2016B 2.40% Senior Notes due April 1, 2021. An amount equal to the proceeds from the Series 2016A 3.25% Senior Notes due April 1, 2026 will be allocated to eligible green expenditures, including financing of or investments in solar power generation facilities or electric vehicle charging infrastructure, or payments under PPAs served by solar power or wind generation facilities. The proceeds from the Series 2016B 2.40% Senior Notes due April 1, 2021 were used to repay at maturity $250 million aggregate principal amount of Georgia Power's Series 2013B Floating Rate Senior Notes due March 15, 2016, to repay a portion of Georgia Power's short-term indebtedness, and for general corporate purposes, including Georgia Power's continuous construction program. Mississippi Power In January 2016, Mississippi Power issued a floating rate promissory note to Southern Company in an aggregate principal amount of up to $275 million , which matures on December 1, 2017, bearing interest based on one-month LIBOR. As of March 31, 2016, Mississippi Power had borrowed $100 million under this promissory note with a $50 million draw occurring on each of January 29, 2016 and March 14, 2016. In addition, on January 19, 2016, Mississippi Power borrowed $100 million from Southern Company pursuant to a promissory note issued in November 2015. On March 8, 2016, Mississippi Power entered into an unsecured term loan agreement for an aggregate amount of $1.2 billion to repay existing indebtedness and for other general corporate purposes. Mississippi Power borrowed $900 million under the term loan agreement and has the right to borrow the remaining $300 million on or before October 15, 2016, upon satisfaction of certain customary conditions. Mississippi Power used the initial proceeds to repay $900 million in maturing bank notes on March 8, 2016 and expects the remaining $300 million to be used to repay senior notes maturing in October 2016. The term loan pursuant to this agreement matures on April 1, 2018 and bears interest based on one-month LIBOR. Also in March 2016, Mississippi Power renewed a $10 million short-term note, which matures on June 30, 2016, bearing interest based on three-month LIBOR. Southern Power During the three months ended March 31, 2016, Southern Power's subsidiary repaid $3 million of long-term debt payable to Turner Renewable Energy, LLC (TRE) and borrowed $2 million due February 28, 2036 under promissory notes payable to TRE. During the three months ended March 31, 2016, Southern Power's subsidiaries borrowed $276 million pursuant to the Project Credit Facilities at a weighted average interest rate of 1.99% . In addition, Southern Power's subsidiaries issued $8 million in letters of credit.

Retirement Benefits

Retirement Benefits	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
RETIREMENT BENEFITS	RETIREMENT BENEFITS Southern Company has a defined benefit, trusteed, pension plan covering substantially all employees. The qualified pension plan is funded in accordance with requirements of the Employee Retirement Income Security Act of 1974, as amended. No mandatory contributions to the qualified pension plan are anticipated for the year ending December 31, 2016 . Southern Company also provides certain defined benefit pension plans for a selected group of management and highly compensated employees. Benefits under these non-qualified pension plans are funded on a cash basis. In addition, Southern Company provides certain medical care and life insurance benefits for retired employees through other postretirement benefit plans. The traditional 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 months ended March 31, 2016 were as follows: Pension Plans Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Three Months Ended March 31, 2016 Service cost $ 62 $ 14 $ 17 $ 3 $ 3 Interest cost 100 24 34 5 5 Expected return on plan assets (187 ) (46 ) (64 ) (9 ) (9 ) Amortization: Prior service costs 4 1 1 — — Net (gain)/loss 38 10 14 2 2 Net cost $ 17 $ 3 $ 2 $ 1 $ 1 Three Months Ended March 31, 2015 Service cost $ 64 $ 15 $ 18 $ 3 $ 3 Interest cost 111 26 38 5 5 Expected return on plan assets (181 ) (45 ) (63 ) (8 ) (8 ) Amortization: Prior service costs 6 2 3 — — Net (gain)/loss 54 14 19 3 3 Net cost $ 54 $ 12 $ 15 $ 3 $ 3 Postretirement Benefits Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Three Months Ended March 31, 2016 Service cost $ 5 $ 1 $ 2 $ — $ — Interest cost 18 5 8 1 1 Expected return on plan assets (14 ) (6 ) (6 ) — — Amortization: Prior service costs 2 1 — — — Net (gain)/loss 3 — 2 — — Net cost $ 14 $ 1 $ 6 $ 1 $ 1 Three Months Ended March 31, 2015 Service cost $ 6 $ 1 $ 2 $ — $ — Interest cost 19 5 8 1 1 Expected return on plan assets (15 ) (6 ) (6 ) — — Amortization: Prior service costs 1 1 — — — Net (gain)/loss 5 — 3 — — Net cost $ 16 $ 1 $ 7 $ 1 $ 1

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Current and Deferred Income Taxes Southern Power ITC Carryforwards As of March 31, 2016 , Southern Power had federal ITC carryforwards which are expected to result in $694 million of federal income tax benefits compared to $551 million as of December 31, 2015. The carryforwards as of March 31, 2016 begin expiring in 2034 but are expected to be utilized by the end of 2021. 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. Southern Company Southern Company's effective tax rate is typically lower than the statutory rate due to employee stock plans' dividend deduction, non-taxable AFUDC equity, and federal income tax benefits from ITCs and PTCs. Southern Company's effective tax rate was 30.8% for the three months ended March 31, 2016 compared to 34.3% for the corresponding period in 2015 . The effective tax rate decrease was primarily due to increased federal income tax benefits from ITCs and PTCs and lower pre-tax earnings in 2016 . Mississippi Power Mississippi Power's effective tax rate was (838.7)% for the three months ended March 31, 2016 compared to 10.0% for the corresponding period in 2015. The effective tax rate decrease was primarily due to an increase in tax benefits related to the estimated probable losses on construction of the Kemper IGCC. Southern Power Southern Power's effective tax rate was (84.0)% for the three months ended March 31, 2016 compared to 25.8% for the corresponding period in 2015 . The effective tax rate decrease was primarily due to increased federal income tax benefits from ITCs related to solar projects expected to be placed in service in 2016 and additional PTCs related to wind projects in 2016 compared to 2015. Unrecognized Tax Benefits See Note 5 to the financial statements of each registrant under "Unrecognized Tax Benefits" in Item 8 of the Form 10-K for additional information. Changes during 2016 for unrecognized tax benefits were as follows: Mississippi Power Southern Power Southern Company (in millions) Unrecognized tax benefits as of December 31, 2015 $ 421 $ 8 $ 433 Tax positions from current periods — 5 5 Balance as of March 31, 2016 $ 421 $ 13 $ 438 The tax positions from current periods primarily relate to federal income tax benefits from ITCs. The impact on the effective tax rate, if recognized, is as follows: As of March 31, 2016 As of December 31, 2015 Mississippi Power Southern Power Southern Company Southern Company (in millions) Tax positions impacting the effective tax rate $ (2 ) $ 13 $ 15 $ 10 Tax positions not impacting the effective tax rate 423 — 423 423 Balance of unrecognized tax benefits $ 421 $ 13 $ 438 $ 433 The tax positions impacting the effective tax rate primarily relate to federal income tax benefits from ITCs. The tax positions not impacting the effective tax rate relate to deductions for Kemper IGCC-related research and experimental (R&E) expenditures. See "Section 174 Research and Experimental Deduction" below for additional information. These amounts are presented on a gross basis without considering the related federal or state income tax impact. Accrued interest for unrecognized tax benefits was immaterial for all periods presented. All of the registrants classify interest on tax uncertainties as interest expense. None of the registrants accrued any penalties on uncertain tax positions. It is reasonably possible that the amount of the unrecognized tax benefits could change within 12 months . The settlement of federal and state audits could impact the balances significantly. At this time, an estimate of the range of reasonably possible outcomes cannot be determined. The IRS has finalized its audits of Southern Company's consolidated federal income tax returns through 2012. Southern Company has filed its 2013 and 2014 federal income tax returns and has received partial acceptance letters from the IRS; however, the IRS has not finalized its audits. Southern Company is a participant in the Compliance Assurance Process of the IRS. The audits for the Southern Company's state income tax returns have either been concluded, or the statute of limitations has expired, for years prior to 2011. Section 174 Research and Experimental Deduction Southern Company has reflected deductions for R&E expenditures related to the Kemper IGCC in its federal income tax calculations since 2013 and has filed amended federal income tax returns for 2008 through 2013 to also include such deductions. The Kemper IGCC is based on first-of-a-kind technology, and Southern Company and Mississippi Power believe that a significant portion of the plant costs qualify as deductible R&E expenditures under Internal Revenue Code Section 174. 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 $423 million and associated interest of $12 million as of March 31, 2016 . The ultimate outcome of this matter cannot be determined at this time.

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2016
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) 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. 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) 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 March 31, 2016 , the net volume of energy-related derivative contracts for natural gas positions for the Southern Company system, together with the longest hedge date over which the respective entity is hedging its exposure to the variability in future cash flows for forecasted transactions and the longest non-hedge date for derivatives not designated as hedges, were as follows: Net Purchased mmBtu Longest Hedge Date Longest Non-Hedge Date (in millions) Southern Company 235 2020 2017 Alabama Power 60 2019 — Georgia Power 65 2019 — Gulf Power 74 2020 — Mississippi Power 28 2018 — Southern Power 8 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 4 million mmBtu for Southern Company and Georgia Power. For cash flow hedges, the amounts expected to be reclassified from accumulated OCI to earnings for the next 12-month period ending March 31, 2017 are immaterial for all registrants. Interest Rate Derivatives Southern Company and certain subsidiaries may also enter into interest rate derivatives to hedge exposure to changes in interest rates. The derivatives employed as hedging instruments are structured to minimize ineffectiveness. Derivatives related to existing variable rate securities or forecasted transactions are accounted for as cash flow hedges where the effective portion of the derivatives' fair value gains or losses is recorded in OCI and is reclassified into earnings at the same time the hedged transactions affect earnings, with any ineffectiveness recorded directly to earnings. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings, providing an offset, with any difference representing ineffectiveness. Fair value gains or losses on derivatives that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred. At March 31, 2016 , the following interest rate derivatives were outstanding: Notional Amount Interest Rate Received Weighted Average Interest Rate Paid Hedge Maturity Date Fair Value (in millions) (in millions) Cash Flow Hedges of Forecasted Debt Southern Company $ 1,500 3-month 2.14% November 2026 $ (55 ) Southern Company 1,200 3-month 2.60% November 2046 (127 ) Gulf Power 80 3-month 2.32% December 2026 (4 ) Cash Flow Hedges of Existing Debt Georgia Power 200 3-month 1.01% August 2016 — Fair Value Hedges on Existing Debt Southern Company 250 1.30% 3-month August 2017 1 Southern Company 300 2.75% 3-month June 2020 10 Georgia Power 250 5.40% 3-month June 2018 3 Georgia Power 200 4.25% 3-month December 2019 6 Georgia Power 500 1.95% 3-month December 2018 5 Derivatives not Designated as Hedges Southern Power 65 (a,d) 3-month 2.50% October 2016 (e) — Southern Power 47 (b,d) 3-month 2.21% October 2016 (e) — Southern Power 65 (c,d) 3-month 2.21% November 2016 (f) — Total $ 4,657 $ (161 ) (a) Swaption at RE Tranquillity LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (b) Swaption at RE Roserock LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (c) Swaption at RE Garland Holdings LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (d) Amortizing notional amount. (e) Represents the mandatory settlement date. Settlement will be based on a 15 -year amortizing swap. (f) Represents the mandatory settlement date. Settlement will be based on a 12 -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 March 31, 2017 are immaterial for all registrants. Southern Company and certain subsidiaries have deferred gains and losses that are expected to be amortized into earnings through 2046. Derivative Financial Statement Presentation and Amounts At March 31, 2016 , the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at March 31, 2016 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 $ 2 $ 1 $ 1 $ — $ — Other deferred charges and assets 5 2 3 — — Total derivatives designated as hedging instruments for regulatory purposes $ 7 $ 3 $ 4 $ — $ — N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets (*) $ 4 $ — $ — $ — $ — $ 4 Interest rate derivatives: Other current assets 18 — 7 — — — Other deferred charges and assets 14 — 7 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 36 $ — $ 14 $ — $ — $ 4 Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets (*) $ 1 $ — $ — $ — $ — $ 1 Interest rate derivatives: Other current assets (*) 1 — — — — 1 Total derivatives not designated as hedging instruments $ 2 $ — $ — $ — $ — $ 2 Total asset derivatives $ 45 $ 3 $ 18 $ — $ — $ 6 (*) Southern Power includes current assets related to derivatives in "Assets from risk management activities." Liability Derivatives at March 31, 2016 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Liabilities from risk management activities (*) $ 124 $ 37 $ 9 $ 49 $ 29 Other deferred credits and liabilities 74 12 2 45 15 Total derivatives designated as hedging instruments for regulatory purposes $ 198 $ 49 $ 11 $ 94 $ 44 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Liabilities from risk management activities (*) $ 2 $ — $ — $ — $ — $ 2 Interest rate derivatives: Liabilities from risk management activities (*) 193 — — 5 — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 195 $ — $ — $ 5 $ — $ 2 Derivatives not designated as hedging instruments Energy-related derivatives: Liabilities from risk management activities (*) $ 1 $ — $ — $ — $ — $ 1 Total liability derivatives $ 394 $ 49 $ 11 $ 99 $ 44 $ 3 (*) Georgia Power, Mississippi Power, and Southern Power include current liabilities related to derivatives in "Other current liabilities." At December 31, 2015 , the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at December 31, 2015 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets $ 3 $ 1 $ 2 $ — $ — N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets (*) $ 3 $ — $ — $ — $ — $ 3 Interest rate derivatives: Other current assets 19 — 5 1 — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 22 $ — $ 5 $ 1 $ — $ 3 Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets (*) $ 1 $ — $ — $ — $ — $ 1 Interest rate derivatives: Other current assets (*) 3 — — — — 3 Total derivatives not designated as hedging instruments $ 4 $ — $ — $ — $ — $ 4 Total asset derivatives $ 29 $ 1 $ 7 $ 1 $ — $ 7 (*) Southern Power includes current assets related to derivatives in "Assets from risk management activities." Liability Derivatives at December 31, 2015 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Liabilities from risk management activities (*) $ 130 $ 40 $ 12 $ 49 $ 29 Other deferred credits and liabilities 87 15 3 51 18 Total derivatives designated as hedging instruments for regulatory purposes $ 217 $ 55 $ 15 $ 100 $ 47 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Liabilities from risk management activities (*) $ 2 $ — $ — $ — $ — $ 2 Interest rate derivatives: Liabilities from risk management activities 23 15 — — — — Other deferred credits and liabilities 7 — 6 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 32 $ 15 $ 6 $ — $ — $ 2 Derivatives not designated as hedging instruments Energy-related derivatives: Liabilities from risk management activities (*) $ 1 $ — $ — $ — $ — $ 1 Total liability derivatives $ 250 $ 70 $ 21 $ 100 $ 47 $ 3 (*) Georgia Power, Mississippi Power, and Southern Power include current liabilities related to derivatives in "Other current liabilities." 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 March 31, 2016 and December 31, 2015 are presented in the following tables. Derivative Contracts at March 31, 2016 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) $ 12 $ 3 $ 4 $ — $ — $ 5 Gross amounts not offset in the Balance Sheet (b) (10 ) (3 ) (3 ) — — (2 ) Net energy-related derivative assets $ 2 $ — $ 1 $ — $ — $ 3 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 33 $ — $ 14 $ — $ — $ 1 Gross amounts not offset in the Balance Sheet (b) (21 ) — — — — — Net interest rate derivative assets $ 12 $ — $ 14 $ — $ — $ 1 Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 201 $ 49 $ 11 $ 94 $ 44 $ 3 Gross amounts not offset in the Balance Sheet (b) (10 ) (3 ) (3 ) — — (2 ) Net energy-related derivative liabilities $ 191 $ 46 $ 8 $ 94 $ 44 $ 1 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 193 $ — $ — $ 5 $ — $ — Gross amounts not offset in the Balance Sheet (b) (21 ) — — — — — Net interest rate derivative liabilities $ 172 $ — $ — $ 5 $ — $ — (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, 2015 Fair Value Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Assets Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 7 $ 1 $ 2 $ — $ — $ 4 Gross amounts not offset in the Balance Sheet (b) (6 ) (1 ) (2 ) — — (1 ) Net energy-related derivative assets $ 1 $ — $ — $ — $ — $ 3 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 22 $ — $ 5 $ 1 $ — $ 4 Gross amounts not offset in the Balance Sheet (b) (9 ) — (4 ) — — — Net interest rate derivative assets $ 13 $ — $ 1 $ 1 $ — $ 4 Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 220 $ 55 $ 15 $ 100 $ 47 $ 3 Gross amounts not offset in the Balance Sheet (b) (6 ) (1 ) (2 ) — — (1 ) Net energy-related derivative liabilities $ 214 $ 54 $ 13 $ 100 $ 47 $ 2 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 30 $ 15 $ 6 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (9 ) — (4 ) — — — Net interest rate derivative liabilities $ 21 $ 15 $ 2 $ — $ — $ — (a) 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 March 31, 2016 and December 31, 2015 , the pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments designated as regulatory hedging instruments and deferred were as follows: Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet at March 31, 2016 Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Energy-related derivatives: Other regulatory assets, current $ (124 ) $ (37 ) $ (9 ) $ (49 ) $ (29 ) Other regulatory assets, deferred (74 ) (12 ) (2 ) (45 ) (15 ) Other regulatory liabilities, current (a) 2 1 1 — — Other regulatory liabilities, deferred (b) 5 2 3 — — Total energy-related derivative gains (losses) $ (191 ) $ (46 ) $ (7 ) $ (94 ) $ (44 ) (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, 2015 Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Energy-related derivatives: Other regulatory assets, current $ (130 ) $ (40 ) $ (12 ) $ (49 ) $ (29 ) Other regulatory assets, deferred (87 ) (15 ) (3 ) (51 ) (18 ) Other regulatory liabilities, current (*) 3 1 2 — — Total energy-related derivative gains (losses) $ (214 ) $ (54 ) $ (13 ) $ (100 ) $ (47 ) (*) Southern Company, Alabama Power, and Georgia Power include other regulatory liabilities, current in other current liabilities. For the three months ended March 31, 2016 and 2015 , 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 2016 2015 2016 2015 (in millions) (in millions) Southern Company Interest rate derivatives $ (190 ) $ (29 ) Interest expense, net of amounts capitalized $ (3 ) $ (2 ) Alabama Power Interest rate derivatives $ (4 ) $ (6 ) Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Georgia Power Interest rate derivatives $ — $ (23 ) Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Gulf Power Interest rate derivatives $ (5 ) $ — Interest expense, net of amounts capitalized $ — $ — For the three months ended March 31, 2016 and 2015 , 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 March 31, 2016 and 2015 , the pre-tax effects of interest rate derivatives designated as fair value hedging instruments were as follows: Derivatives in Fair Value Hedging Relationships Gain (Loss) Derivative Category Statements of Income Location 2016 2015 (in millions) Southern Company Interest rate derivatives: Interest expense, net of amounts capitalized $ 20 $ 7 Georgia Power Interest rate derivatives: Interest expense, net of amounts capitalized $ 14 $ 6 For the three months ended March 31, 2016 and 2015 , the pre-tax effects of interest rate derivatives designated as fair value hedging instruments were offset by changes to the carrying value of long-term debt. There was no material ineffectiveness recorded in earnings for any registrant for any period presented. For the three months ended March 31, 2016 and 2015 , the pre-tax effects of energy-related derivatives and interest rate derivatives not designated as hedging instruments were immaterial for all registrants. Contingent Features 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 March 31, 2016 , the registrants' collateral posted with their derivative counterparties was immaterial. At March 31, 2016 , the fair value of derivative liabilities with contingent features was $49 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 $49 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	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS Southern Company Proposed Merger with AGL Resources On August 23, 2015, Southern Company entered into the Merger Agreement to acquire AGL Resources. 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. 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. Through May 5, 2016, the Maryland PSC, the Georgia PSC, the California Public Utilities Commission, and the Virginia State Corporation Commission have approved the Merger. On April 15, 2016, Southern Company, AGL Resources, and Northern Illinois Gas Company (collectively, the Joint Applicants) and the Retail Energy Supply Association filed a settlement agreement with the Illinois Commerce Commission. On April 28, 2016, the Joint Applicants, the Illinois Attorney General's Office, and the Citizens Utility Board filed a settlement agreement with the Illinois Commerce Commission. Collectively, these agreements resolve all remaining contested issues for Illinois Commerce Commission approval of the Merger. On May 5, 2016, Southern Company, AGL Resources, Merger Sub, Pivotal Utility Holdings, Inc. d/b/a Elizabethtown Gas, the Division of Rate Counsel, the Staff of the New Jersey Board of Public Utilities, and New Jersey Large Energy Users Coalition entered into a comprehensive settlement agreement relating to the New Jersey Board of Public Utilities review of the Merger. Additionally, the Federal Communications Commission (FCC) has approved the transfer of control over the FCC licenses of certain AGL Resources subsidiaries. Consummation of the Merger remains subject to the satisfaction or waiver of certain closing conditions, including, among others, (i) the approval of the Illinois Commerce Commission and the New Jersey Board of Public Utilities and other approvals required under applicable state laws, (ii) 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 (iii) 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. During the first quarter 2016, Southern Company recorded in its statements of income external transaction costs for financing, legal, and consulting services associated with the proposed Merger of approximately $20 million , of which $6 million is included in operating expenses and $14 million is included in other income and (expense). The ultimate outcome of these matters cannot be determined at this time. See Note 12 to the financial statements of Southern Company under "Southern Company – Proposed Merger with AGL Resources" in Item 8 of the Form 10-K for additional information. Merger Financing Southern Company intends to fund the cash consideration for the Merger using a mix of debt and equity. Southern Company expects to issue the debt to fund the cash consideration for the Merger in several tranches including long-dated maturities. The amount of debt issued at each maturity will depend on prevailing market conditions at the time of the offering and other factors. 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 6 to the financial statements of Southern Company under "Bank Credit Arrangements" in Item 8 of the Form 10-K for additional information regarding the Bridge Agreement. Proposed Acquisition of PowerSecure On February 24, 2016, Southern Company entered into an Agreement and Plan of Merger to acquire PowerSecure. Under the terms of this merger agreement, the stockholders of PowerSecure will be entitled to receive $18.75 in cash for each share of common stock in a transaction with a total purchase price of approximately $431 million . Following this transaction, PowerSecure will become a wholly-owned subsidiary of Southern Company. This transaction is expected to close in May 2016. The ultimate outcome of this matter cannot be determined at this time. Southern Power See Note 2 to the financial statements of Southern Power and Note 12 to the financial statements of Southern Company under "Southern Power" in Item 8 of the Form 10-K for additional information. During the first quarter 2016, the fair values of the assets and liabilities acquired of Lost Hills, Blackwell, North Star, and Morelos were finalized and there were no changes. During 2016, in accordance with its overall growth strategy, Southern Power acquired or contracted to acquire through its wholly-owned subsidiaries, Southern Renewable Partnerships, LLC or Southern Renewable Energy, Inc., the projects set forth in the following table. Acquisition-related costs were expensed as incurred and were not material. The acquisitions do not include any contingent consideration unless specifically noted. Project Facility Seller; Acquisition Date Approx. Nameplate Capacity Location Southern Power Percentage Ownership Expected/Actual COD PPA PPA Contract Period Approx. Purchase Price (MW) (in millions) SOLAR Calipatria Solar Frontier Americas Holding, LLC 20 Imperial County, CA 90 % February 11, 2016 San Diego Gas & Electric Company 20 years $ 51 (a) East Pecos First Solar, Inc. March 4, 2016 120 Pecos County, TX 100 % Fourth quarter 2016 Austin Energy 15 years $ 41 (b) WIND Grant Wind Apex Clean Energy Holdings, LLC 151 Grant County, OK 100 % April 8, 2016 Western Farmers, East Texas, and Northeast Texas Electric Cooperative 20 years $ 258 (c) Passadumkeag Quantam Wind Acquisition I, LLC 40 Penobscot County, ME 100 % Second quarter 2016 Western Massachusetts Electric Company 15 years $ 127 (d) (a) Calipatria - The total purchase price, including the minority owner, TRE's 10% ownership interest and contingent consideration of $6 million , is approximately $57 million . As of March 31, 2016, the fair values of the assets and liabilities acquired through the business combination were recorded as follows: $58 million as property, plant, and equipment, $1 million as a transmission interconnection prepaid, and $2 million as payables; however, the allocation of the purchase price to individual assets has not been finalized. (b) East Pecos - The total purchase price is approximately $41 million . As of March 31, 2016, the fair values of the assets acquired through the business combination were recorded as $41 million to CWIP; however, the allocation of the purchase price to individual assets has not been finalized. Total construction costs, which include the acquisition price allocated to CWIP, are expected to be approximately $200 million to $220 million . The ultimate outcome of this matter cannot be determined at this time. (c) Grant Wind - Subsequent to March 31, 2016, Southern Power acquired all of the outstanding membership interests of Grant Wind, LLC. The purchase price includes approximately $23 million of contingent consideration which may be adjusted based on performance testing and production over the first 10 years of operation. (d) Passadumkeag - On March 11, 2016, Southern Power entered into an agreement to acquire all of the outstanding membership interests of Quantum Wind Acquisition I, LLC, which is expected to close in the second quarter 2016. The ultimate outcome of this matter cannot be determined at this time. Construction Projects During the first quarter 2016, in accordance with its overall growth strategy, Southern Power completed construction of and placed in service the Butler Solar Farm and Pawpaw solar facilities. In addition, Southern Power continued construction of the projects set forth in the table below. Through March 31, 2016 , total costs of construction incurred for the projects below were $2.2 billion , of which $1.5 billion remains in CWIP. The ultimate outcome of these matters cannot be determined at this time. Solar Facility Seller Approx. Nameplate Capacity Location Expected/Actual COD PPA Counterparties PPA Estimated Construction Costs (MW) (in millions) Butler CERSM, LLC and Community Energy, Inc. 103 Taylor County, GA Fourth quarter 2016 Georgia Power (a) 30 years $ 220 - 230 (b) Desert Stateline First Solar, Inc. 299 (c) San Bernardino County, CA Through third quarter 2016 Southern California Edison Company (SCE) 20 years $ 1,200 - 1,300 (d) Garland and Recurrent Energy, LLC 205 Kern County, CA Fourth quarter 2016 Third quarter 2016 SCE 15 years and $ 532 - 552 (e,f) Roserock Recurrent Energy, LLC 160 Pecos County, TX Fourth quarter 2016 Austin Energy 20 years $ 333 - 353 (e,f) Sandhills N/A 146 Taylor County, GA Fourth quarter 2016 Cobb, Flint, Irwin, Middle Georgia and Sawnee Electric Membership Corporations 25 years $ 260 - 280 Tranquillity Recurrent Energy, LLC 205 Fresno County, CA Third quarter 2016 Shell Energy North America (US), LP/SCE 18 years $ 473 - 493 (f,g) (a) Butler - Affiliate PPA subject to FERC approval. (b) Butler - Total estimated construction costs include the acquisition price of all outstanding membership interests of the related entity. (c) Desert Stateline - The facility has a total of 299 MWs, of which 110 MWs were placed in service in the fourth quarter 2015 and 76 MWs were placed in service in the first quarter 2016. Subsequent to March 31, 2016, 38 MWs were placed in service. The remaining 75 MWs are expected to be placed in service by the end of the third quarter 2016. (d) Desert Stateline - On March 29, 2016, Southern Power acquired an additional 15% interest in Desert Stateline. As a result, Southern Power and the class B member are entitled to 66% and 34% , respectively, of all cash distributions from Desert Stateline. In addition, Southern Power will continue to be entitled to substantially all of the federal tax benefits with respect to the transaction. Total estimated construction costs include the acquisition price allocated to CWIP; however, the allocation of the purchase price to individual assets has not been finalized. (e) Total estimated construction costs include the acquisition price allocated to CWIP. During the first quarter 2016, the allocation of the purchase price to individual assets was finalized with no changes. (f) Southern Power owns 100% of the class A membership interests and a wholly-owned subsidiary of the seller owns 100% of the class B membership interests. Southern Power and the class B member are entitled to 51% and 49% , respectively, of all cash distributions from the project. (g) Total estimated construction costs include the acquisition price allocated to CWIP; however, the allocation of the purchase price to individual assets has not been finalized.

Segment and Related Information

Segment and Related Information	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
SEGMENT AND RELATED INFORMATION	SEGMENT AND RELATED INFORMATION The primary business of the Southern Company system is electricity sales by the traditional 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 $97 million and $114 million for the three months ended March 31, 2016 and March 31, 2015 , 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 months ended March 31, 2016 and 2015 was as follows: Electric Utilities Traditional Operating Companies Southern Power Eliminations Total All Other Eliminations Consolidated (in millions) Three Months Ended March 31, 2016: Operating revenues $ 3,742 $ 315 $ (103 ) $ 3,954 $ 47 $ (36 ) $ 3,965 Segment net income (loss) (a)(b) 464 50 — 514 (26 ) (3 ) 485 Total assets at March 31, 2016 $ 69,240 $ 8,999 $ (396 ) $ 77,843 $ 2,070 $ (1,178 ) $ 78,735 Three Months Ended March 31, 2015: Operating revenues $ 3,948 $ 348 $ (124 ) $ 4,172 $ 40 $ (29 ) $ 4,183 Segment net income (loss) (a)(b) 477 33 — 510 3 (5 ) 508 Total assets at December 31, 2015 $ 69,052 $ 8,905 $ (397 ) $ 77,560 $ 1,819 $ (1,061 ) $ 78,318 (a) Attributable to Southern Company. (b) Segment net income (loss) for the traditional operating companies includes pre-tax charges for estimated probable losses on the Kemper IGCC of $53 million ( $33 million after tax) and $9 million ( $6 million after tax) for the three months ended March 31, 2016 and 2015 , respectively. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate" for additional information. Products and Services Electric Utilities' Revenues Period Retail Wholesale Other Total (in millions) Three Months Ended March 31, 2016 $ 3,377 $ 396 $ 181 $ 3,954 Three Months Ended March 31, 2015 3,542 467 163 4,172

Introduction (Policies)

Introduction (Policies)	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting	The condensed quarterly financial statements of each registrant included herein have been prepared by such registrant, without audit, pursuant to the rules and regulations of the SEC. The Condensed Balance Sheets as of December 31, 2015 have been derived from the audited financial statements of each registrant. In the opinion of each registrant's management, the information regarding such registrant furnished herein reflects all adjustments, which, except as otherwise disclosed, are of a normal recurring nature, necessary to present fairly the results of operations for the periods ended March 31, 2016 and 2015 . Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, although each registrant believes that the disclosures regarding such registrant are adequate to make the information presented not misleading. Disclosures which would substantially duplicate the disclosures in the Form 10-K and details which have not changed significantly in amount or composition since the filing of the Form 10-K are generally omitted from this Quarterly Report on Form 10-Q unless specifically required by GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K. Due to the seasonal variations in the demand for energy, operating results for the periods presented are not necessarily indicative of the operating results to be expected for the full year.
Reclassification	Certain prior year data presented in the financial statements have been reclassified to conform to the current year presentation. These reclassifications had no impact on the results of operations, financial position, or cash flows of any registrant.
Recently Issued Accounting Standards	Recently Issued Accounting Standards On February 25, 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 requires lessees to recognize on the balance sheet a lease liability and a right-of-use asset for all leases. ASU 2016-02 also changes the recognition, measurement, and presentation of expense associated with leases and provides clarification regarding the identification of certain components of contracts that would represent a lease. The accounting required by lessors is relatively unchanged and there is no change to the accounting for existing leveraged leases. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The registrants are currently evaluating the new standard and have not yet determined its ultimate impact; however, adoption of ASU 2016-02 is expected to have a significant impact on Southern Company and the traditional operating companies' balance sheets. On March 30, 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). ASU 2016-09 changes the accounting for income taxes and the cash flow presentation for share-based payment award transactions. Most significantly, entities are required to recognize all excess tax benefits and deficiencies related to the exercise or vesting of stock compensation as income tax expense or benefit in the income statement. Southern Company and the traditional operating companies currently recognize any excess tax benefits and deficiencies related to the exercise and vesting of stock compensation in additional paid-in capital. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, with early adoption permitted. Southern Company and the traditional operating companies are currently evaluating the new standard and have not yet determined its ultimate impact.
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 products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflect the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and occasionally, implied volatility of interest rate options. The interest rate derivatives are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note (H) for additional information on how these derivatives are used. The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. For fair value measurements of the investments within the nuclear decommissioning trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available. See Note 1 to the financial statements of Southern Company, Alabama Power, and Georgia Power under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information. "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	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. 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) 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. 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.

Contingencies and Regulatory 20

Contingencies and Regulatory Matters (Tables)	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Recovery Balance of Each Regulatory Clause	The balance of each regulatory clause recovery on the balance sheet follows: Regulatory Clause Balance Sheet Line Item March 31, 2016 December 31, 2015 (in millions) Rate CNP Compliance Under recovered regulatory clause revenues, current $ 22 $ 43 Rate CNP PPA Deferred under recovered regulatory clause revenues 105 99 Retail Energy Cost Recovery Other regulatory liabilities, current 173 238 Deferred over recovered regulatory clause revenues 64 — Natural Disaster Reserve Other regulatory liabilities, deferred 74 75 The balance of each regulatory clause recovery on the balance sheet follows: Regulatory Clause Balance Sheet Location March 31, 2016 December 31, 2015 (in millions) Fuel Cost Recovery Other regulatory liabilities, current $ 20 $ 18 Purchased Power Capacity Recovery Under recovered regulatory clause revenues 4 1 Environmental Cost Recovery Under recovered regulatory clause revenues 17 19 Energy Conservation Cost Recovery Other regulatory liabilities, current 2 4
Current And Actual Cost Estimate for Kemper IGCC	Mississippi Power's Kemper IGCC 2010 project estimate, current cost estimate (which includes the impacts of the Mississippi Supreme Court's (Court) decision discussed herein under "Rate Recovery of Kemper IGCC Costs – 2013 MPSC Rate Order"), and actual costs incurred as of March 31, 2016 , are as follows: Cost Category 2010 Project Estimate (f) Current Cost Estimate (a) Actual Costs (in billions) Plant Subject to Cost Cap (b)(g) $ 2.40 $ 5.35 $ 4.99 Lignite Mine and Equipment 0.21 0.23 0.23 CO 2 Pipeline Facilities 0.14 0.11 0.12 AFUDC (c) 0.17 0.71 0.62 Combined Cycle and Related Assets Placed in (d)(g) — 0.02 0.01 General Exceptions 0.05 0.10 0.09 Deferred Costs (e)(g) — 0.20 0.18 Additional DOE Grants (h) — (0.14 ) — Total Kemper IGCC $ 2.97 $ 6.58 $ 6.24 (a) Amounts in the Current Cost Estimate reflect estimated costs through September 30, 2016. (b) The 2012 MPSC CPCN Order approved a construction cost cap of up to $2.88 billion , net of the Initial DOE Grants and excluding the Cost Cap Exceptions. The Current Cost Estimate and the Actual Costs include non-incremental operating and maintenance costs related to the combined cycle and associated common facilities placed in service in August 2014 that are subject to the $2.88 billion cost cap and exclude post-in-service costs for the lignite mine. See "Rate Recovery of Kemper IGCC Costs – 2013 MPSC Rate Order" herein for additional information. The Current Cost Estimate and the Actual Costs reflect 100% of the costs of the Kemper IGCC. See note (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" herein 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" herein. (f) The 2010 Project Estimate is the certificated cost estimate adjusted to include the certificated estimate for the CO 2 pipeline facilities approved in 2011 by the Mississippi PSC. (g) Beginning in the third quarter 2015, certain costs, including debt carrying costs (associated with assets placed in service and other non-CWIP 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 the Actual Costs at March 31, 2016 . (h) On April 8, 2016, Mississippi Power received approximately $137 million in additional grants from the DOE for the Kemper IGCC, which are expected to be used to reduce future rate impacts for customers.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value on a recurring basis	As of March 31, 2016 , assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows: Fair Value Measurements Using As of March 31, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Southern Company Assets: Energy-related derivatives $ — $ 12 $ — $ — $ 12 Interest rate derivatives — 33 — — 33 Nuclear decommissioning trusts (a) 624 898 — 16 1,538 Cash equivalents 503 — — — 503 Other investments 9 — 1 — 10 Total $ 1,136 $ 943 $ 1 $ 16 $ 2,096 Liabilities: Energy-related derivatives $ — $ 201 $ — $ — $ 201 Interest rate derivatives — 193 — — 193 Total $ — $ 394 $ — $ — $ 394 Alabama Power Assets: Energy-related derivatives $ — $ 3 $ — $ — $ 3 Nuclear decommissioning trusts (b) Domestic equity 365 67 — — 432 Foreign equity 46 48 — — 94 U.S. Treasury and government agency securities — 25 — — 25 Corporate bonds 11 137 — — 148 Mortgage and asset backed securities — 21 — — 21 Private Equity — — — 16 16 Other — 9 — — 9 Cash equivalents 321 — — — 321 Total $ 743 $ 310 $ — $ 16 $ 1,069 Liabilities: Energy-related derivatives $ — $ 49 $ — $ — $ 49 Fair Value Measurements Using As of March 31, 2016: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value as a Practical Expedient (NAV) Total (in millions) Georgia Power Assets: Energy-related derivatives $ — $ 4 $ — $ — $ 4 Interest rate derivatives — 14 — — 14 Nuclear decommissioning trusts (b) (c) Domestic equity 180 1 — — 181 Foreign equity — 115 — — 115 U.S. Treasury and government agency securities — 111 — — 111 Municipal bonds — 66 — — 66 Corporate bonds — 146 — — 146 Mortgage and asset backed securities — 145 — — 145 Other 22 7 — — 29 Cash equivalents 57 — — — 57 Total $ 259 $ 609 $ — $ — $ 868 Liabilities: Energy-related derivatives $ — $ 11 $ — $ — $ 11 Gulf Power Assets: Cash equivalents $ 20 $ — $ — $ — $ 20 Liabilities: Energy-related derivatives $ — $ 94 $ — $ — $ 94 Interest rate derivatives — 5 — — 5 Total $ — $ 99 $ — $ — $ 99 Mississippi Power Assets: Cash equivalents $ 24 $ — $ — $ — $ 24 Liabilities: Energy-related derivatives $ — $ 44 $ — $ — $ 44 Southern Power Assets: Energy-related derivatives $ — $ 5 $ — $ — $ 5 Interest rate derivatives — 1 — — 1 Cash equivalents 39 — — — 39 Total $ 39 $ 6 $ — $ — $ 45 Liabilities: Energy-related derivatives $ — $ 3 $ — $ — $ 3 (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 March 31, 2016 , approximately $58 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 March 31, 2016 , the fair value measurements of private equity investments held in the nuclear decommissioning trust that are calculated at net asset value per share (or its equivalent) as a practical expedient, as well as the nature and risks of those investments, were as follows: As of March 31, 2016: Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period (in millions) Southern Company $ 16 $ 29 Not Applicable Not Applicable Alabama Power $ 16 $ 29 Not Applicable Not Applicable
Financial instruments for which carrying amount did not equal fair value	As of March 31, 2016 , other financial instruments for which the carrying amount did not equal fair value were as follows: Carrying Amount Fair Value (in millions) Long-term debt, including securities due within one year: Southern Company $ 28,341 $ 29,827 Alabama Power $ 7,089 $ 7,688 Georgia Power $ 10,549 $ 11,400 Gulf Power $ 1,303 $ 1,366 Mississippi Power $ 3,209 $ 2,938 Southern Power $ 3,123 $ 3,171

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
Earnings per Share	Shares used to compute diluted earnings per share were as follows: Three Months Ended March 31, 2016 Three Months Ended March 31, 2015 (in millions) As reported shares 916 910 Effect of options and performance share award units 6 5 Diluted shares 922 915
Changes in Stockholders' Equity	The following table presents year-to-date changes in stockholders' equity of Southern Company: Number of Common Shares Common Preferred and Preference Stock of Subsidiaries Total Issued Treasury Noncontrolling Interests (*) (in thousands) (in millions) Balance at December 31, 2015 915,073 (3,352 ) $ 20,592 $ 609 $ 781 $ 21,982 Consolidated net income attributable to Southern Company — — 485 — — 485 Other comprehensive income (loss) — — (114 ) — — (114 ) Stock issued 6,572 — 270 — — 270 Stock-based compensation — — 60 — — 60 Cash dividends on common stock — — (497 ) — — (497 ) Contributions from noncontrolling interests — — — — 129 129 Distributions to noncontrolling interests — — — — (4 ) (4 ) Purchase of membership interests from noncontrolling interests — — — — (129 ) (129 ) Net income attributable to noncontrolling interests — — — — 1 1 Other — (35 ) 1 — — 1 Balance at March 31, 2016 921,645 (3,387 ) $ 20,797 $ 609 $ 778 $ 22,184 Balance at December 31, 2014 908,502 (725 ) $ 19,949 $ 756 $ 221 $ 20,926 Consolidated net income attributable to Southern Company — — 508 — — 508 Other comprehensive income (loss) — — (15 ) — — (15 ) Stock issued 3,094 — 112 — — 112 Stock-based compensation — — 53 — — 53 Stock repurchased, at cost — (2,599 ) (115 ) — — (115 ) Cash dividends on common stock — — (478 ) — — (478 ) Other — (11 ) 3 — — 3 Balance at March 31, 2015 911,596 (3,335 ) $ 20,017 $ 756 $ 221 $ 20,994 (*) Primarily related to Southern Power Company.

Financing (Tables)

Financing (Tables)	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Credit arrangements by company	The following table outlines the committed credit arrangements by company as of March 31, 2016 : Expires Executable Term Loans Due Within One Year Company 2016 2017 2018 2020 Total Unused One Year Two Years Term Out No Term Out (in millions) (in millions) (in millions) Southern Company (a) $ — $ — $ 1,000 $1,250 $ 2,250 $ 2,250 $ — $ — $ — $ — Alabama Power 40 — 500 800 1,340 1,340 — — — 40 Georgia Power — — — 1,750 1,750 1,732 — — — — Gulf Power 75 40 165 — 280 280 45 — 45 40 Mississippi Power 205 — — — 205 180 30 15 45 160 Southern Power Company (b) — — — 600 600 560 — — — — Other 70 — — — 70 70 20 — 20 50 Total $ 390 $ 40 $ 1,665 $4,400 $ 6,495 $ 6,412 $ 95 $ 15 $ 110 $ 290 (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) Excluding its subsidiaries. See "Project Credit Facilities" below and Note (I) under "Southern Power" for additional information. The table below summarizes each Project Credit Facility as of March 31, 2016 . Project Maturity Date Construction Loan Facility Bridge Loan Facility Total Total Undrawn Letter of Credit Facility Total Undrawn (in millions) Tranquillity Earlier of COD or December 31, 2016 $ 86 $ 172 $ 258 $ 52 $ 77 $ 26 Roserock Earlier of COD or November 30, 2016 63 180 243 121 23 16 Garland Earlier of COD or November 30, 2016 86 308 394 309 49 32 Total $ 235 $ 660 $ 895 $ 482 $ 149 $ 74
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 three months of 2016 : Company (a) Senior Note Issuances Senior Note Maturities and Redemptions Revenue Other Long-Term Debt Issuances Other Long-Term Debt Redemptions and Maturities (b) (in millions) Alabama Power $ 400 $ 200 $ — $ 45 $ — Georgia Power 650 250 4 — 1 Mississippi Power — — — 1,100 426 Southern Power — — — 2 3 Other — — — — 4 Elimination (c) — — — (200 ) — Total $ 1,050 $ 450 $ 4 $ 947 $ 434 (a) Southern Company and Gulf Power did not issue or redeem any long-term debt during the first three months of 2016. (b) Includes reductions in capital lease obligations resulting from cash payments under capital leases. (c) Intercompany loans from Southern Company to Mississippi Power eliminated in Southern Company's Consolidated Financial Statements.

Retirement Benefits (Tables)

Retirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Pension Plans and Postretirement Plans	Components of the net periodic benefit costs for the three months ended March 31, 2016 were as follows: Pension Plans Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Three Months Ended March 31, 2016 Service cost $ 62 $ 14 $ 17 $ 3 $ 3 Interest cost 100 24 34 5 5 Expected return on plan assets (187 ) (46 ) (64 ) (9 ) (9 ) Amortization: Prior service costs 4 1 1 — — Net (gain)/loss 38 10 14 2 2 Net cost $ 17 $ 3 $ 2 $ 1 $ 1 Three Months Ended March 31, 2015 Service cost $ 64 $ 15 $ 18 $ 3 $ 3 Interest cost 111 26 38 5 5 Expected return on plan assets (181 ) (45 ) (63 ) (8 ) (8 ) Amortization: Prior service costs 6 2 3 — — Net (gain)/loss 54 14 19 3 3 Net cost $ 54 $ 12 $ 15 $ 3 $ 3 Postretirement Benefits Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Three Months Ended March 31, 2016 Service cost $ 5 $ 1 $ 2 $ — $ — Interest cost 18 5 8 1 1 Expected return on plan assets (14 ) (6 ) (6 ) — — Amortization: Prior service costs 2 1 — — — Net (gain)/loss 3 — 2 — — Net cost $ 14 $ 1 $ 6 $ 1 $ 1 Three Months Ended March 31, 2015 Service cost $ 6 $ 1 $ 2 $ — $ — Interest cost 19 5 8 1 1 Expected return on plan assets (15 ) (6 ) (6 ) — — Amortization: Prior service costs 1 1 — — — Net (gain)/loss 5 — 3 — — Net cost $ 16 $ 1 $ 7 $ 1 $ 1

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Change in Unrecognized Tax Benefits	Changes during 2016 for unrecognized tax benefits were as follows: Mississippi Power Southern Power Southern Company (in millions) Unrecognized tax benefits as of December 31, 2015 $ 421 $ 8 $ 433 Tax positions from current periods — 5 5 Balance as of March 31, 2016 $ 421 $ 13 $ 438
Impact on Effective Tax Rate, If Recognized	The impact on the effective tax rate, if recognized, is as follows: As of March 31, 2016 As of December 31, 2015 Mississippi Power Southern Power Southern Company Southern Company (in millions) Tax positions impacting the effective tax rate $ (2 ) $ 13 $ 15 $ 10 Tax positions not impacting the effective tax rate 423 — 423 423 Balance of unrecognized tax benefits $ 421 $ 13 $ 438 $ 433

Derivatives (Tables)

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of derivatives	At March 31, 2016 , the net volume of energy-related derivative contracts for natural gas positions for the Southern Company system, together with the longest hedge date over which the respective entity is hedging its exposure to the variability in future cash flows for forecasted transactions and the longest non-hedge date for derivatives not designated as hedges, were as follows: Net Purchased mmBtu Longest Hedge Date Longest Non-Hedge Date (in millions) Southern Company 235 2020 2017 Alabama Power 60 2019 — Georgia Power 65 2019 — Gulf Power 74 2020 — Mississippi Power 28 2018 — Southern Power 8 2016 2017
Notional amount of interest rate derivatives	At March 31, 2016 , the following interest rate derivatives were outstanding: Notional Amount Interest Rate Received Weighted Average Interest Rate Paid Hedge Maturity Date Fair Value (in millions) (in millions) Cash Flow Hedges of Forecasted Debt Southern Company $ 1,500 3-month 2.14% November 2026 $ (55 ) Southern Company 1,200 3-month 2.60% November 2046 (127 ) Gulf Power 80 3-month 2.32% December 2026 (4 ) Cash Flow Hedges of Existing Debt Georgia Power 200 3-month 1.01% August 2016 — Fair Value Hedges on Existing Debt Southern Company 250 1.30% 3-month August 2017 1 Southern Company 300 2.75% 3-month June 2020 10 Georgia Power 250 5.40% 3-month June 2018 3 Georgia Power 200 4.25% 3-month December 2019 6 Georgia Power 500 1.95% 3-month December 2018 5 Derivatives not Designated as Hedges Southern Power 65 (a,d) 3-month 2.50% October 2016 (e) — Southern Power 47 (b,d) 3-month 2.21% October 2016 (e) — Southern Power 65 (c,d) 3-month 2.21% November 2016 (f) — Total $ 4,657 $ (161 ) (a) Swaption at RE Tranquillity LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (b) Swaption at RE Roserock LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (c) Swaption at RE Garland Holdings LLC. See Note 12 to the financial statements of Southern Company and Note 2 to the financial statements of Southern Power in Item 8 of the Form 10-K for additional information. (d) Amortizing notional amount. (e) Represents the mandatory settlement date. Settlement will be based on a 15 -year amortizing swap. (f) Represents the mandatory settlement date. Settlement will be based on a 12 -year amortizing swap.
Fair value of energy-related derivatives and interest rate derivatives	At March 31, 2016 , the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at March 31, 2016 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 $ 2 $ 1 $ 1 $ — $ — Other deferred charges and assets 5 2 3 — — Total derivatives designated as hedging instruments for regulatory purposes $ 7 $ 3 $ 4 $ — $ — N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets (*) $ 4 $ — $ — $ — $ — $ 4 Interest rate derivatives: Other current assets 18 — 7 — — — Other deferred charges and assets 14 — 7 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 36 $ — $ 14 $ — $ — $ 4 Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets (*) $ 1 $ — $ — $ — $ — $ 1 Interest rate derivatives: Other current assets (*) 1 — — — — 1 Total derivatives not designated as hedging instruments $ 2 $ — $ — $ — $ — $ 2 Total asset derivatives $ 45 $ 3 $ 18 $ — $ — $ 6 (*) Southern Power includes current assets related to derivatives in "Assets from risk management activities." Liability Derivatives at March 31, 2016 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Liabilities from risk management activities (*) $ 124 $ 37 $ 9 $ 49 $ 29 Other deferred credits and liabilities 74 12 2 45 15 Total derivatives designated as hedging instruments for regulatory purposes $ 198 $ 49 $ 11 $ 94 $ 44 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Liabilities from risk management activities (*) $ 2 $ — $ — $ — $ — $ 2 Interest rate derivatives: Liabilities from risk management activities (*) 193 — — 5 — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 195 $ — $ — $ 5 $ — $ 2 Derivatives not designated as hedging instruments Energy-related derivatives: Liabilities from risk management activities (*) $ 1 $ — $ — $ — $ — $ 1 Total liability derivatives $ 394 $ 49 $ 11 $ 99 $ 44 $ 3 (*) Georgia Power, Mississippi Power, and Southern Power include current liabilities related to derivatives in "Other current liabilities." At December 31, 2015 , the fair value of energy-related derivatives and interest rate derivatives was reflected in the balance sheets as follows: Asset Derivatives at December 31, 2015 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Other current assets $ 3 $ 1 $ 2 $ — $ — N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Other current assets (*) $ 3 $ — $ — $ — $ — $ 3 Interest rate derivatives: Other current assets 19 — 5 1 — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 22 $ — $ 5 $ 1 $ — $ 3 Derivatives not designated as hedging instruments Energy-related derivatives: Other current assets (*) $ 1 $ — $ — $ — $ — $ 1 Interest rate derivatives: Other current assets (*) 3 — — — — 3 Total derivatives not designated as hedging instruments $ 4 $ — $ — $ — $ — $ 4 Total asset derivatives $ 29 $ 1 $ 7 $ 1 $ — $ 7 (*) Southern Power includes current assets related to derivatives in "Assets from risk management activities." Liability Derivatives at December 31, 2015 Fair Value Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Derivatives designated as hedging instruments for regulatory purposes Energy-related derivatives: Liabilities from risk management activities (*) $ 130 $ 40 $ 12 $ 49 $ 29 Other deferred credits and liabilities 87 15 3 51 18 Total derivatives designated as hedging instruments for regulatory purposes $ 217 $ 55 $ 15 $ 100 $ 47 N/A Derivatives designated as hedging instruments in cash flow and fair value hedges Energy-related derivatives: Liabilities from risk management activities (*) $ 2 $ — $ — $ — $ — $ 2 Interest rate derivatives: Liabilities from risk management activities 23 15 — — — — Other deferred credits and liabilities 7 — 6 — — — Total derivatives designated as hedging instruments in cash flow and fair value hedges $ 32 $ 15 $ 6 $ — $ — $ 2 Derivatives not designated as hedging instruments Energy-related derivatives: Liabilities from risk management activities (*) $ 1 $ — $ — $ — $ — $ 1 Total liability derivatives $ 250 $ 70 $ 21 $ 100 $ 47 $ 3 (*) Georgia Power, Mississippi Power, and Southern Power include current liabilities related to derivatives in "Other current liabilities."
Offsetting disclosure tables	Amounts related to energy-related derivative contracts and interest rate derivative contracts at March 31, 2016 and December 31, 2015 are presented in the following tables. Derivative Contracts at March 31, 2016 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) $ 12 $ 3 $ 4 $ — $ — $ 5 Gross amounts not offset in the Balance Sheet (b) (10 ) (3 ) (3 ) — — (2 ) Net energy-related derivative assets $ 2 $ — $ 1 $ — $ — $ 3 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 33 $ — $ 14 $ — $ — $ 1 Gross amounts not offset in the Balance Sheet (b) (21 ) — — — — — Net interest rate derivative assets $ 12 $ — $ 14 $ — $ — $ 1 Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 201 $ 49 $ 11 $ 94 $ 44 $ 3 Gross amounts not offset in the Balance Sheet (b) (10 ) (3 ) (3 ) — — (2 ) Net energy-related derivative liabilities $ 191 $ 46 $ 8 $ 94 $ 44 $ 1 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 193 $ — $ — $ 5 $ — $ — Gross amounts not offset in the Balance Sheet (b) (21 ) — — — — — Net interest rate derivative liabilities $ 172 $ — $ — $ 5 $ — $ — (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, 2015 Fair Value Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power Southern Power (in millions) Assets Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 7 $ 1 $ 2 $ — $ — $ 4 Gross amounts not offset in the Balance Sheet (b) (6 ) (1 ) (2 ) — — (1 ) Net energy-related derivative assets $ 1 $ — $ — $ — $ — $ 3 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 22 $ — $ 5 $ 1 $ — $ 4 Gross amounts not offset in the Balance Sheet (b) (9 ) — (4 ) — — — Net interest rate derivative assets $ 13 $ — $ 1 $ 1 $ — $ 4 Liabilities Energy-related derivatives: Energy-related derivatives presented in the Balance Sheet (a) $ 220 $ 55 $ 15 $ 100 $ 47 $ 3 Gross amounts not offset in the Balance Sheet (b) (6 ) (1 ) (2 ) — — (1 ) Net energy-related derivative liabilities $ 214 $ 54 $ 13 $ 100 $ 47 $ 2 Interest rate derivatives: Interest rate derivatives presented in the Balance Sheet (a) $ 30 $ 15 $ 6 $ — $ — $ — Gross amounts not offset in the Balance Sheet (b) (9 ) — (4 ) — — — Net interest rate derivative liabilities $ 21 $ 15 $ 2 $ — $ — $ — (a) 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 March 31, 2016 and December 31, 2015 , the pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments designated as regulatory hedging instruments and deferred were as follows: Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet at March 31, 2016 Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Energy-related derivatives: Other regulatory assets, current $ (124 ) $ (37 ) $ (9 ) $ (49 ) $ (29 ) Other regulatory assets, deferred (74 ) (12 ) (2 ) (45 ) (15 ) Other regulatory liabilities, current (a) 2 1 1 — — Other regulatory liabilities, deferred (b) 5 2 3 — — Total energy-related derivative gains (losses) $ (191 ) $ (46 ) $ (7 ) $ (94 ) $ (44 ) (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, 2015 Derivative Category and Balance Sheet Location Southern Company Alabama Power Georgia Power Gulf Power Mississippi Power (in millions) Energy-related derivatives: Other regulatory assets, current $ (130 ) $ (40 ) $ (12 ) $ (49 ) $ (29 ) Other regulatory assets, deferred (87 ) (15 ) (3 ) (51 ) (18 ) Other regulatory liabilities, current (*) 3 1 2 — — Total energy-related derivative gains (losses) $ (214 ) $ (54 ) $ (13 ) $ (100 ) $ (47 ) (*) Southern Company, Alabama Power, and Georgia Power include other regulatory liabilities, current in other current liabilities.
Pre-tax effects of interest rate derivatives, designated as cash flow hedging instruments	For the three months ended March 31, 2016 and 2015 , 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 2016 2015 2016 2015 (in millions) (in millions) Southern Company Interest rate derivatives $ (190 ) $ (29 ) Interest expense, net of amounts capitalized $ (3 ) $ (2 ) Alabama Power Interest rate derivatives $ (4 ) $ (6 ) Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Georgia Power Interest rate derivatives $ — $ (23 ) Interest expense, net of amounts capitalized $ (1 ) $ (1 ) Gulf Power Interest rate derivatives $ (5 ) $ — Interest expense, net of amounts capitalized $ — $ —
Pre-tax effects of interest rate derivatives, designated as fair value hedging instruments	For the three months ended March 31, 2016 and 2015 , the pre-tax effects of interest rate derivatives designated as fair value hedging instruments were as follows: Derivatives in Fair Value Hedging Relationships Gain (Loss) Derivative Category Statements of Income Location 2016 2015 (in millions) Southern Company Interest rate derivatives: Interest expense, net of amounts capitalized $ 20 $ 7 Georgia Power Interest rate derivatives: Interest expense, net of amounts capitalized $ 14 $ 6

Acquisitions (Tables)

Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
Schedule of Business Acquisitions	During 2016, in accordance with its overall growth strategy, Southern Power acquired or contracted to acquire through its wholly-owned subsidiaries, Southern Renewable Partnerships, LLC or Southern Renewable Energy, Inc., the projects set forth in the following table. Acquisition-related costs were expensed as incurred and were not material. The acquisitions do not include any contingent consideration unless specifically noted. Project Facility Seller; Acquisition Date Approx. Nameplate Capacity Location Southern Power Percentage Ownership Expected/Actual COD PPA PPA Contract Period Approx. Purchase Price (MW) (in millions) SOLAR Calipatria Solar Frontier Americas Holding, LLC 20 Imperial County, CA 90 % February 11, 2016 San Diego Gas & Electric Company 20 years $ 51 (a) East Pecos First Solar, Inc. March 4, 2016 120 Pecos County, TX 100 % Fourth quarter 2016 Austin Energy 15 years $ 41 (b) WIND Grant Wind Apex Clean Energy Holdings, LLC 151 Grant County, OK 100 % April 8, 2016 Western Farmers, East Texas, and Northeast Texas Electric Cooperative 20 years $ 258 (c) Passadumkeag Quantam Wind Acquisition I, LLC 40 Penobscot County, ME 100 % Second quarter 2016 Western Massachusetts Electric Company 15 years $ 127 (d) (a) Calipatria - The total purchase price, including the minority owner, TRE's 10% ownership interest and contingent consideration of $6 million , is approximately $57 million . As of March 31, 2016, the fair values of the assets and liabilities acquired through the business combination were recorded as follows: $58 million as property, plant, and equipment, $1 million as a transmission interconnection prepaid, and $2 million as payables; however, the allocation of the purchase price to individual assets has not been finalized. (b) East Pecos - The total purchase price is approximately $41 million . As of March 31, 2016, the fair values of the assets acquired through the business combination were recorded as $41 million to CWIP; however, the allocation of the purchase price to individual assets has not been finalized. Total construction costs, which include the acquisition price allocated to CWIP, are expected to be approximately $200 million to $220 million . The ultimate outcome of this matter cannot be determined at this time. (c) Grant Wind - Subsequent to March 31, 2016, Southern Power acquired all of the outstanding membership interests of Grant Wind, LLC. The purchase price includes approximately $23 million of contingent consideration which may be adjusted based on performance testing and production over the first 10 years of operation. (d) Passadumkeag - On March 11, 2016, Southern Power entered into an agreement to acquire all of the outstanding membership interests of Quantum Wind Acquisition I, LLC, which is expected to close in the second quarter 2016. The ultimate outcome of this matter cannot be determined at this time.
Schedule of Construction Projects	Through March 31, 2016 , total costs of construction incurred for the projects below were $2.2 billion , of which $1.5 billion remains in CWIP. The ultimate outcome of these matters cannot be determined at this time. Solar Facility Seller Approx. Nameplate Capacity Location Expected/Actual COD PPA Counterparties PPA Estimated Construction Costs (MW) (in millions) Butler CERSM, LLC and Community Energy, Inc. 103 Taylor County, GA Fourth quarter 2016 Georgia Power (a) 30 years $ 220 - 230 (b) Desert Stateline First Solar, Inc. 299 (c) San Bernardino County, CA Through third quarter 2016 Southern California Edison Company (SCE) 20 years $ 1,200 - 1,300 (d) Garland and Recurrent Energy, LLC 205 Kern County, CA Fourth quarter 2016 Third quarter 2016 SCE 15 years and $ 532 - 552 (e,f) Roserock Recurrent Energy, LLC 160 Pecos County, TX Fourth quarter 2016 Austin Energy 20 years $ 333 - 353 (e,f) Sandhills N/A 146 Taylor County, GA Fourth quarter 2016 Cobb, Flint, Irwin, Middle Georgia and Sawnee Electric Membership Corporations 25 years $ 260 - 280 Tranquillity Recurrent Energy, LLC 205 Fresno County, CA Third quarter 2016 Shell Energy North America (US), LP/SCE 18 years $ 473 - 493 (f,g) (a) Butler - Affiliate PPA subject to FERC approval. (b) Butler - Total estimated construction costs include the acquisition price of all outstanding membership interests of the related entity. (c) Desert Stateline - The facility has a total of 299 MWs, of which 110 MWs were placed in service in the fourth quarter 2015 and 76 MWs were placed in service in the first quarter 2016. Subsequent to March 31, 2016, 38 MWs were placed in service. The remaining 75 MWs are expected to be placed in service by the end of the third quarter 2016. (d) Desert Stateline - On March 29, 2016, Southern Power acquired an additional 15% interest in Desert Stateline. As a result, Southern Power and the class B member are entitled to 66% and 34% , respectively, of all cash distributions from Desert Stateline. In addition, Southern Power will continue to be entitled to substantially all of the federal tax benefits with respect to the transaction. Total estimated construction costs include the acquisition price allocated to CWIP; however, the allocation of the purchase price to individual assets has not been finalized. (e) Total estimated construction costs include the acquisition price allocated to CWIP. During the first quarter 2016, the allocation of the purchase price to individual assets was finalized with no changes. (f) Southern Power owns 100% of the class A membership interests and a wholly-owned subsidiary of the seller owns 100% of the class B membership interests. Southern Power and the class B member are entitled to 51% and 49% , respectively, of all cash distributions from the project.

Segment and Related Informati28

Segment and Related Information (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Financial data for business segments	Financial data for business segments and products and services for the three months ended March 31, 2016 and 2015 was as follows: Electric Utilities Traditional Operating Companies Southern Power Eliminations Total All Other Eliminations Consolidated (in millions) Three Months Ended March 31, 2016: Operating revenues $ 3,742 $ 315 $ (103 ) $ 3,954 $ 47 $ (36 ) $ 3,965 Segment net income (loss) (a)(b) 464 50 — 514 (26 ) (3 ) 485 Total assets at March 31, 2016 $ 69,240 $ 8,999 $ (396 ) $ 77,843 $ 2,070 $ (1,178 ) $ 78,735 Three Months Ended March 31, 2015: Operating revenues $ 3,948 $ 348 $ (124 ) $ 4,172 $ 40 $ (29 ) $ 4,183 Segment net income (loss) (a)(b) 477 33 — 510 3 (5 ) 508 Total assets at December 31, 2015 $ 69,052 $ 8,905 $ (397 ) $ 77,560 $ 1,819 $ (1,061 ) $ 78,318 (a) Attributable to Southern Company. (b) Segment net income (loss) for the traditional operating companies includes pre-tax charges for estimated probable losses on the Kemper IGCC of $53 million ( $33 million after tax) and $9 million ( $6 million after tax) for the three months ended March 31, 2016 and 2015 , respectively. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate" for additional information.
Financial data for products and services	Products and Services Electric Utilities' Revenues Period Retail Wholesale Other Total (in millions) Three Months Ended March 31, 2016 $ 3,377 $ 396 $ 181 $ 3,954 Three Months Ended March 31, 2015 3,542 467 163 4,172

Contingencies and Regulatory 29

Contingencies and Regulatory Matters - Recovery Balance of Each Regulatory Clause - Alabama Power (Details) - Alabama Power [Member] - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Under recovered regulatory clause revenues, current [Member]
Loss Contingencies [Line Items]
Rate CNP Compliance	$ 22	$ 43
Deferred under recovered regulatory clause revenues [Member]
Loss Contingencies [Line Items]
Rate CNP PPA	105	99
Other regulatory liabilities, current [Member]
Loss Contingencies [Line Items]
Retail Energy Cost Recovery	173	238
Deferred Over Recovered Regulatory Clause Revenues [Member]
Loss Contingencies [Line Items]
Retail Energy Cost Recovery	64	0
Other regulatory liabilities, deferred [Member]
Loss Contingencies [Line Items]
Natural Disaster Reserve	$ 74	$ 75

Contingencies and Regulatory 30

Contingencies and Regulatory Matters - Recovery Balance of Each Regulatory Clause - Gulf Power (Details) - Gulf Power [Member] - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Under recovered regulatory clause revenues [Member]
Loss Contingencies [Line Items]
Purchased Power Capacity Recovery	$ 4	$ 1
Other regulatory liabilities, current [Member]
Loss Contingencies [Line Items]
Fuel Cost Recovery	20	18
Environmental Cost Recovery	17	19
Energy Conservation Cost Recovery	$ 2	$ 4

Contingencies and Regulatory 31

Contingencies and Regulatory Matters - Current And Actual Cost Estimate (Details) - Mississippi Power [Member] - USD ($) $ in Millions	Apr. 08, 2016	Mar. 31, 2016	Dec. 31, 2012	Oct. 06, 2014
Loss Contingencies [Line Items]
Cost Related to Grant Funding			$ 245
Kemper IGCC [Member]
Loss Contingencies [Line Items]
Plant Subject to Cost Cap		$ 4,990	$ 2,880
Lignite Mine and Equipment		230
CO2 Pipeline Facilities		120
AFUDC		620
Combined Cycle and Related Assets Placed in Service – Incremental		10
General Exceptions		90
Deferred Costs		180
Total Kemper IGCC, Actual Costs		6,240
Cost Related to Grant Funding		$ 0
Purchase of Interest		100.00%		15.00%
Project Estimate [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Plant Subject to Cost Cap		$ 2,400
Lignite Mine and Equipment		210
CO2 Pipeline Facilities		140
AFUDC		170
Combined Cycle and Related Assets Placed in Service – Incremental		0
General Exceptions		50
Deferred Costs		0
Total Kemper IGCC, Actual Costs		2,970
Cost Related to Grant Funding		0
Current Estimate [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Plant Subject to Cost Cap		5,350
Lignite Mine and Equipment		230
CO2 Pipeline Facilities		110
AFUDC		710
Combined Cycle and Related Assets Placed in Service – Incremental		20
General Exceptions		100
Deferred Costs		200
Total Kemper IGCC, Actual Costs		6,580
Cost Related to Grant Funding		$ (140)
Subsequent Event [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Government Grants Received	$ 137

Contingencies and Regulatory 32

Contingencies and Regulatory Matters - Narrative (Details)	May. 01, 2016USD ($)	Apr. 08, 2016USD ($)	Dec. 03, 2015USD ($)	Jul. 07, 2015USD ($)	Jun. 30, 2015USD ($)	Apr. 15, 2015USD ($)	Jan. 01, 2014USD ($)	Mar. 19, 2013	Dec. 31, 2015USD ($)	Feb. 28, 2013USD ($)	Jan. 31, 2013USD ($)	Mar. 31, 2016USD ($)clausemiMW	Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2010	Dec. 31, 2009USD ($)	Dec. 31, 2008USD ($)	Mar. 31, 2016USD ($)mi	Dec. 31, 2022	Apr. 14, 2016USD ($)	Apr. 01, 2016USD ($)	Feb. 01, 2016USD ($)	Jan. 13, 2016USD ($)	Jan. 05, 2016USD ($)	Jul. 10, 2015USD ($)	Oct. 06, 2014
Loss Contingencies [Line Items]
Maximum Borrowing Capacity												$ 6,495,000,000											$ 6,495,000,000
Construction in Progress, Gross									$ 9,082,000,000			9,406,000,000		$ 9,082,000,000		$ 9,082,000,000							9,406,000,000
Other Regulatory Assets Deferred									4,989,000,000			4,957,000,000		4,989,000,000		4,989,000,000							4,957,000,000
Projected Balance Of Regulatory Assets									402,000,000			394,000,000		402,000,000		402,000,000							394,000,000
Kemper IGCC [Member]
Loss Contingencies [Line Items]
Pre-Tax Charge To Income												53,000,000	$ 9,000,000
After Tax Charge To Income												33,000,000	$ 6,000,000
Georgia Power [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation												28,000,000											28,000,000
Additional Construction Capital Costs					$ 3,100,000,000							5,440,000,000		160,000,000
Percentage of Proportionate Share Owed in Consortium Agreement																						45.70%
Maximum Borrowing Capacity												$ 1,750,000,000											1,750,000,000
Increase (Decrease) In Projected Certified Construction Capital Costs												5.00%
Estimated In-service Capital Cost																					$ 4,400,000,000
Amendment To Estimated In-service Capital Cost										$ 4,800,000,000
Delay Of Estimated In-service Date						18 months
Construction in Progress, Gross									4,775,000,000			$ 4,817,000,000		4,775,000,000		4,775,000,000							4,817,000,000
Other Regulatory Assets Deferred									2,152,000,000			2,138,000,000		2,152,000,000		2,152,000,000							2,138,000,000
Projected Balance Of Regulatory Assets									123,000,000			126,000,000		123,000,000		123,000,000							126,000,000
Georgia Power [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Additional Construction Capital Costs																						$ 114,000,000
Georgia Power [Member] | Other Current Liabilities [Member]
Loss Contingencies [Line Items]
Over Recovered Fuel Balance												177,000,000											177,000,000
Georgia Power [Member] | Other deferred credits and liabilities [Member]
Loss Contingencies [Line Items]
Over Recovered Fuel Balance									116,000,000					116,000,000		116,000,000
Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member]
Loss Contingencies [Line Items]
Maximum Borrowing Capacity																												$ 920,000,000
Estimated In-service Capital Cost						$ 5,000,000,000
Monthly Operational Readiness Costs						$ 10,000,000
Monthly Financing Costs												27,000,000
Construction Financing Costs												2,400,000,000
Construction in Progress, Gross												3,700,000,000											3,700,000,000
Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Project Settlement Cost To Be Capitalized									350,000,000					350,000,000		350,000,000
Project Settlement Cost To Be Capitalized, Amount Paid To Date									241,000,000					241,000,000		241,000,000
Gulf Power [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Assets Previously Disposed, Liability for Remediation												46,000,000											46,000,000
Maximum Borrowing Capacity												280,000,000											280,000,000
Construction in Progress, Gross									48,000,000			57,000,000		48,000,000		48,000,000							57,000,000
Reduction In Depreciation Expense																		$ 62,500,000
Reduction In Depreciation Expense Year One												$ 5,600,000				20,100,000	$ 8,400,000
Number Of Regulatory Clauses | clause												4
Other Regulatory Assets Deferred									427,000,000			$ 420,000,000		427,000,000		427,000,000							420,000,000
Projected Balance Of Regulatory Assets									90,000,000			90,000,000		90,000,000		90,000,000							90,000,000
Mississippi Power [Member]
Loss Contingencies [Line Items]
Ownership Percentage in Project One																			50.00%
Over Recovered Fuel Cost									71,000,000			80,000,000		71,000,000		71,000,000							80,000,000
Approved Increase (Decrease) in Annual Billing Based on Fuel Cost Recovery Rate																											$ (36,000,000)		$ (120,000,000)
Maximum Borrowing Capacity												205,000,000											205,000,000
Construction in Progress, Gross									2,254,000,000			$ 2,400,000,000		2,254,000,000		2,254,000,000							$ 2,400,000,000
Annual PEP Filing Rate Increase Amount																										$ 5,000,000
Plant Capacity Under Coal Gasification Combined Cycle Technology (in MWs) | MW												582
Co Two Pipeline Infrastructure (in miles) | mi												61											61
Costs associated with CCP12 grant funds																			$ 245,000,000
Other Property And Investments												$ 6,000,000											$ 6,000,000
Lignite Mining Costs												75,000,000											75,000,000
Materials, Supplies, and Other												45,000,000											45,000,000
Cost deferred in other regulatory assets												22,000,000											22,000,000
Other Regulatory Assets Deferred									525,000,000			520,000,000		525,000,000		525,000,000							520,000,000
Other deferred charges and assets												11,000,000											11,000,000
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				$ 29,000,000
Projected Balance Of Regulatory Assets									95,000,000			101,000,000		95,000,000		95,000,000							101,000,000
Regulatory Liabilities												$ 3,000,000											$ 3,000,000
Percentage of Carbon Dioxide Captured from Project												70.00%											70.00%
Percentage of Contract to Purchase Carbon Dioxide from Project												30.00%											30.00%
Mississippi Power [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Costs Due To Extension Of In-service Date												$ 25,000,000
Mississippi Power [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Costs Due To Extension Of In-service Date												35,000,000
Mississippi Power [Member] | Construction in Progress [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss												2,470,000,000											$ 2,470,000,000
Mississippi Power [Member] | MRA Revenue [Member]
Loss Contingencies [Line Items]
Over Recovered Fuel Cost									24,000,000			25,000,000		$ 24,000,000		$ 24,000,000							25,000,000
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] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Estimated Cost												4,990,000,000							$ 2,880,000,000
Costs associated with CCP12 grant funds												0
Other Regulatory Assets Deferred												196,000,000											196,000,000
Pre-Tax Charge To Income												53,000,000											2,470,000,000
After Tax Charge To Income												33,000,000											$ 1,520,000,000
Monthly Charge Of Allowance For Equity Funds Used During Construction												14,000,000
Monthly Cost Regulatory Assets Deferred												$ 2,000,000
Purchase of Interest												100.00%											100.00%								15.00%
Maximum Cap Construction Cost												$ 6,240,000,000
Regulatory Assets												120,000,000											$ 120,000,000
Projected Balance Of Regulatory Assets												98,000,000											98,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Current Estimate [Member]
Loss Contingencies [Line Items]
Estimated Cost												5,350,000,000
Costs associated with CCP12 grant funds												(140,000,000)
Maximum Cap Construction Cost												$ 6,580,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | In-Service Asset Proposal [Member]
Loss Contingencies [Line Items]
PSC Retail Rate Increase (Decrease)			$ 126,000,000																											$ 159,000,000
Public Utilities, Approved Equity Capital Structure, Percentage			49.733%
Public Utilities, Approved Return on Equity, Percentage			9.225%
Customer Refund									$ 11,000,000
Period to File Subsequent Rate Request			18 months
Mississippi Power [Member] | Kemper IGCC [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Amortization Period of Regulatory Assets and Liabilities												2 years
Mississippi Power [Member] | Kemper IGCC [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Amortization Period of Regulatory Assets and Liabilities												10 years
Mississippi Power [Member] | Kemper IGCC [Member] | Property, Plant and Equipment [Member]
Loss Contingencies [Line Items]
Estimated Cost												$ 3,610,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Other current assets [Member]
Loss Contingencies [Line Items]
Estimated Cost												1,000,000
Mississippi Power [Member] | Kemper IGCC [Member] | Current Assets [Member]
Loss Contingencies [Line Items]
Regulatory Assets												$ 22,000,000											$ 22,000,000
Mississippi Power [Member] | Mine [Member]
Loss Contingencies [Line Items]
Term of Management Fee Contract																				40 years
Subsequent Event [Member] | Georgia Power [Member]
Loss Contingencies [Line Items]
Rate ECR Increase Decrease																									15.00%
Approved Increase (Decrease) in Annual Billing Based on Fuel Cost Recovery Rate																									$ (313,000,000)
Subsequent Event [Member] | Mississippi Power [Member]
Loss Contingencies [Line Items]
Increase in Base Rate Under Cost Based Electric Tariff Due to Settlement	$ 7,000,000
Increase (Decrease) in Revenue to be Received from Base Rate Change															$ 5,000,000
AFUDC Cost															$ 6,000,000
Subsequent Event [Member] | Mississippi Power [Member] | Kemper IGCC [Member]
Loss Contingencies [Line Items]
Government Grants Received		$ 137,000,000
Scenario, Forecast [Member] | Georgia Power And Atlanta Gas Light Company [Member]
Loss Contingencies [Line Items]
Percentage Basis, Net Merger Savings																								40.00%
Customers [Member] | Scenario, Forecast [Member]
Loss Contingencies [Line Items]
Percentage Basis, Net Merger Savings																								60.00%

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	$ 12
Interest rate derivatives	33
Nuclear decommissioning trusts	1,538
Cash equivalents	503
Other investments	10
Total	2,096
Liabilities:
Energy-related derivatives	201
Interest rate derivatives	193
Total	394
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	624
Cash equivalents	503
Other investments	9
Total	1,136
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	12
Interest rate derivatives	33
Nuclear decommissioning trusts	898
Cash equivalents	0
Other investments	0
Total	943
Liabilities:
Energy-related derivatives	201
Interest rate derivatives	193
Total	394
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Nuclear decommissioning trusts	0
Cash equivalents	0
Other investments	1
Total	1
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Nuclear decommissioning trusts	16
Cash equivalents	0
Other investments	0
Total	16
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Alabama Power [Member]
Assets:
Energy-related derivatives	3	$ 1
Liabilities:
Energy-related derivatives	49	70
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	3
Cash equivalents	321
Total	1,069
Liabilities:
Energy-related derivatives	49
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	432
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	94
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	25
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	148
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	21
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Assets:
Nuclear decommissioning trusts	16
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	9
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	321
Total	743
Liabilities:
Energy-related derivatives	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	365
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	11
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Private Equity Funds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	3
Cash equivalents	0
Total	310
Liabilities:
Energy-related derivatives	49
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	67
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	48
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	25
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	137
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	21
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Private Equity Funds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	9
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Cash equivalents	0
Total	0
Liabilities:
Energy-related derivatives	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Private Equity Funds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member]
Assets:
Energy-related derivatives	0
Cash equivalents	0
Total	16
Liabilities:
Energy-related derivatives	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Private Equity Funds [Member]
Assets:
Nuclear decommissioning trusts	16
Alabama Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member]
Assets:
Energy-related derivatives	18	7
Nuclear decommissioning trusts	58
Liabilities:
Energy-related derivatives	11	21
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	4
Interest rate derivatives	14
Cash equivalents	57
Total	868
Liabilities:
Energy-related derivatives	11
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	181
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	115
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	111
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	66
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	146
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	145
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	29
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	57
Total	259
Liabilities:
Energy-related derivatives	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	180
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	22
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	4
Interest rate derivatives	14
Cash equivalents	0
Total	609
Liabilities:
Energy-related derivatives	11
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	115
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	111
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	66
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	146
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	145
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	7
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Cash equivalents	0
Total	0
Liabilities:
Energy-related derivatives	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Cash equivalents	0
Total	0
Liabilities:
Energy-related derivatives	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Domestic Equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Foreign equity [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | U.S. Treasury and government agency securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Municipal bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Corporate bonds [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Mortgage and asset backed securities [Member]
Assets:
Nuclear decommissioning trusts	0
Georgia Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member] | Other investments [Member]
Assets:
Nuclear decommissioning trusts	0
Gulf Power [Member]
Assets:
Energy-related derivatives	0	1
Liabilities:
Energy-related derivatives	99	100
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	20
Liabilities:
Energy-related derivatives	94
Interest rate derivatives	5
Total	99
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Cash equivalents	20
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Cash equivalents	0
Liabilities:
Energy-related derivatives	94
Interest rate derivatives	5
Total	99
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Cash equivalents	0
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Gulf Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member]
Assets:
Cash equivalents	0
Liabilities:
Energy-related derivatives	0
Interest rate derivatives	0
Total	0
Mississippi Power [Member]
Assets:
Energy-related derivatives	0	0
Liabilities:
Energy-related derivatives	44	47
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents	24
Liabilities:
Energy-related derivatives	44
Mississippi Power [Member] | Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Cash equivalents	24
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	44
Mississippi 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] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member]
Assets:
Cash equivalents	0
Liabilities:
Energy-related derivatives	0
Southern Power [Member]
Assets:
Energy-related derivatives	6	7
Liabilities:
Energy-related derivatives	3	$ 3
Southern Power [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Energy-related derivatives	5
Interest rate derivatives	1
Cash equivalents	39
Total	45
Liabilities:
Energy-related derivatives	3
Southern 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	39
Total	39
Liabilities:
Energy-related derivatives	0
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Energy-related derivatives	5
Interest rate derivatives	1
Cash equivalents	0
Total	6
Liabilities:
Energy-related derivatives	3
Southern 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
Southern Power [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Net Asset Value As A Practical Expedient [Member]
Assets:
Energy-related derivatives	0
Interest rate derivatives	0
Cash equivalents	0
Total	0
Liabilities:
Energy-related derivatives	$ 0

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Measurements Of Investments Calculated At Net Asset Value Per Share (Details) - Private Equity Funds [Member] $ in Millions	Mar. 31, 2016USD ($)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 16
Unfunded Commitments	29
Alabama Power [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	16
Unfunded Commitments	$ 29

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments for which Carrying Amount did not Equal Fair Value (Details) $ in Millions	Mar. 31, 2016USD ($)
Southern Company [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	$ 28,341
Long-term debt, including securities due within one year, Fair Value	29,827
Alabama Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	7,089
Long-term debt, including securities due within one year, Fair Value	7,688
Georgia Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	10,549
Long-term debt, including securities due within one year, Fair Value	11,400
Gulf Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	1,303
Long-term debt, including securities due within one year, Fair Value	1,366
Mississippi Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	3,209
Long-term debt, including securities due within one year, Fair Value	2,938
Southern Power [Member]
Long-term debt:
Long-term debt, including securities due within one year, Carrying Amount	3,123
Long-term debt, including securities due within one year, Fair Value	$ 3,171

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds	$ (20)	$ (33)
Private Equity Funds [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Liquidating Investment, Remaining Period	10 years
Alabama Power [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds	$ (11)	(15)
Georgia Power [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Increase (decrease) in fair value of funds	$ (9)	$ (18)

Stockholders' Equity - Earnings

Stockholders' Equity - Earnings per Share (Details) - shares shares in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings per Share
As reported shares	916	910
Diluted shares	922	915
Southern Company [Member]
Earnings per Share
As reported shares	916	910
Effect of options and performance share award units	6	5
Diluted shares	922	915

Stockholders' Equity - Changes

Stockholders' Equity - Changes in Stockholders' Equity (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Changes in Stockholders' Equity
Beginning Balance, Treasury Shares	(3,400)
Beginning Balance	$ 21,982	$ 20,926
Consolidated net income attributable to Southern Company	485	508
Other comprehensive income (loss)	(114)	(15)
Stock issued	270	112
Stock-based compensation	60	53
Stock repurchased, at cost		(115)
Cash dividends on common stock	(497)	(478)
Contributions from noncontrolling interests	129
Distributions to noncontrolling interests	(4)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	129
Payments to Noncontrolling Interests	4	0
Net income attributable to noncontrolling interests	1
Other	$ 1	3
Beginning Balance, Treasury Shares	(3,400)
Ending Balance	$ 22,184	$ 20,994
Number of Common shares Issued [Member]
Changes in Stockholders' Equity
Beginning Balance, Shares	915,073	908,502
Stock issued, Shares	6,572	3,094
Ending Balance, Shares	921,645	911,596
Number of Common shares Treasury [Member]
Changes in Stockholders' Equity
Beginning Balance, Treasury Shares	(3,352)	(725)
Stock repurchased, at cost, Shares		(2,599)
Other, Shares	(35)	(11)
Beginning Balance, Treasury Shares	(3,387)	(3,335)
Common Stockholders' Equity [Member]
Changes in Stockholders' Equity
Beginning Balance	$ 20,592	$ 19,949
Consolidated net income attributable to Southern Company	485	508
Other comprehensive income (loss)	(114)	(15)
Stock issued	270	112
Stock-based compensation	60	53
Stock repurchased, at cost		(115)
Cash dividends on common stock	(497)	(478)
Other	1	3
Ending Balance	20,797	20,017
Preferred And Preference Stock [Member]
Changes in Stockholders' Equity
Beginning Balance	609	756
Stock issued		0
Other	0
Ending Balance	609	756
Noncontrolling Interest [Member]
Changes in Stockholders' Equity
Beginning Balance	781	221
Contributions from noncontrolling interests	129
Distributions to noncontrolling interests	(4)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	129
Net income attributable to noncontrolling interests	1
Ending Balance	$ 778	$ 221

Financing - Schedule of Credit

Financing - Schedule of Credit Arrangements (Details) - USD ($)	Mar. 31, 2016	Sep. 30, 2015
Line of Credit Facility [Line Items]
Expires, 2016	$ 390,000,000
Expires, 2017	40,000,000
Expires, 2018	1,665,000,000
Expires, 2020	4,400,000,000
Total	6,495,000,000
Unused	6,412,000,000
Executable Term Loans, One Year	95,000,000
Executable Term Loans, Two Years	15,000,000
Due Within One Year, Term Out	110,000,000
Due Within One Year, No Term Out	290,000,000
Bridge Agreement [Member]
Line of Credit Facility [Line Items]
Total		$ 8,100,000,000
Southern Company [Member]
Line of Credit Facility [Line Items]
Expires, 2016	0
Expires, 2017	0
Expires, 2018	1,000,000,000
Expires, 2020	1,250,000,000
Total	2,250,000,000
Unused	2,250,000,000
Executable Term Loans, One Year	0
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Alabama Power [Member]
Line of Credit Facility [Line Items]
Expires, 2016	40,000,000
Expires, 2017	0
Expires, 2018	500,000,000
Expires, 2020	800,000,000
Total	1,340,000,000
Unused	1,340,000,000
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, 2016	0
Expires, 2017	0
Expires, 2018	0
Expires, 2020	1,750,000,000
Total	1,750,000,000
Unused	1,732,000,000
Executable Term Loans, One Year	0
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Gulf Power [Member]
Line of Credit Facility [Line Items]
Expires, 2016	75,000,000
Expires, 2017	40,000,000
Expires, 2018	165,000,000
Expires, 2020	0
Total	280,000,000
Unused	280,000,000
Executable Term Loans, One Year	45,000,000
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	45,000,000
Due Within One Year, No Term Out	40,000,000
Mississippi Power [Member]
Line of Credit Facility [Line Items]
Expires, 2016	205,000,000
Expires, 2017	0
Expires, 2018	0
Expires, 2020	0
Total	205,000,000
Unused	180,000,000
Executable Term Loans, One Year	30,000,000
Executable Term Loans, Two Years	15,000,000
Due Within One Year, Term Out	45,000,000
Due Within One Year, No Term Out	160,000,000
Southern Power [Member]
Line of Credit Facility [Line Items]
Expires, 2016	0
Expires, 2017	0
Expires, 2018	0
Expires, 2020	600,000,000
Total	600,000,000
Unused	560,000,000
Executable Term Loans, One Year	0
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	0
Due Within One Year, No Term Out	0
Other [Member]
Line of Credit Facility [Line Items]
Expires, 2016	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	20,000,000
Executable Term Loans, Two Years	0
Due Within One Year, Term Out	20,000,000
Due Within One Year, No Term Out	$ 50,000,000

Financing -Schedule of Line of

Financing -Schedule of Line of Credit Facilities (Details)	Mar. 31, 2016USD ($)
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	$ 6,495,000,000
Remaining Borrowing Capacity	6,412,000,000
Southern Power [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	600,000,000
Remaining Borrowing Capacity	560,000,000
Construction Loans [Member] | Southern Power [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	235,000,000
Construction Loans [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	86,000,000
Construction Loans [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	63,000,000
Construction Loans [Member] | Southern Power [Member] | RE Garland Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	86,000,000
Bridge Loan [Member] | Southern Power [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	660,000,000
Bridge Loan [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	172,000,000
Bridge Loan [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	180,000,000
Bridge Loan [Member] | Southern Power [Member] | RE Garland Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	308,000,000
Construction Loan And Bridge Loan [Member] | Southern Power [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	895,000,000
Remaining Borrowing Capacity	482,000,000
Construction Loan And Bridge Loan [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	258,000,000
Remaining Borrowing Capacity	52,000,000
Construction Loan And Bridge Loan [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	243,000,000
Remaining Borrowing Capacity	121,000,000
Construction Loan And Bridge Loan [Member] | Southern Power [Member] | RE Garland Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	394,000,000
Remaining Borrowing Capacity	309,000,000
Letter of Credit [Member] | Southern Power [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	149,000,000
Remaining Borrowing Capacity	74,000,000
Letter of Credit [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	77,000,000
Remaining Borrowing Capacity	26,000,000
Letter of Credit [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	23,000,000
Remaining Borrowing Capacity	16,000,000
Letter of Credit [Member] | Southern Power [Member] | RE Garland Holdings, LLC [Member]
Line of Credit Facility [Line Items]
Maximum Borrowing Capacity	49,000,000
Remaining Borrowing Capacity	$ 32,000,000

Financing - Schedule of Long-Te

Financing - Schedule of Long-Term Debt Financing Activities (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Debt Instrument [Line Items]
Senior Note Issuances	$ 1,050
Senior Note Maturities and Redemptions	450
Revenue Bond Maturities Redemptions and Repurchases	4
Other Long-Term Debt Issuances	947
Other Long-Term Debt Redemptions and Maturities	434
Consolidation, Eliminations [Member]
Debt Instrument [Line Items]
Other Long-Term Debt Issuances	(200)
Alabama Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances	400
Senior Note Maturities and Redemptions	200
Revenue Bond Maturities Redemptions and Repurchases	0
Other Long-Term Debt Issuances	45
Other Long-Term Debt Redemptions and Maturities	0
Georgia Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances	650
Senior Note Maturities and Redemptions	250
Revenue Bond Maturities Redemptions and Repurchases	4
Other Long-Term Debt Issuances	0
Other Long-Term Debt Redemptions and Maturities	1
Mississippi Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances	0
Senior Note Maturities and Redemptions	0
Revenue Bond Maturities Redemptions and Repurchases	0
Other Long-Term Debt Issuances	1,100
Other Long-Term Debt Redemptions and Maturities	426
Southern Power [Member]
Debt Instrument [Line Items]
Senior Note Issuances	0
Senior Note Maturities and Redemptions	0
Revenue Bond Maturities Redemptions and Repurchases	0
Other Long-Term Debt Issuances	2
Other Long-Term Debt Redemptions and Maturities	3
Other [Member]
Debt Instrument [Line Items]
Senior Note Issuances	0
Senior Note Maturities and Redemptions	0
Revenue Bond Maturities Redemptions and Repurchases	0
Other Long-Term Debt Issuances	0
Other Long-Term Debt Redemptions and Maturities	$ 4

Financing - Narrative (Details)

Financing - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended
	Jan. 31, 2016	Mar. 31, 2016	Mar. 14, 2016	Mar. 08, 2016	Jan. 29, 2016	Jan. 19, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support		$ 1,800,000,000
Maximum Borrowing Capacity		6,495,000,000
Remaining Borrowing Capacity		6,412,000,000
Bridge Agreement [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity							$ 8,100,000,000
Scenario, Plan [Member] | Bridge Agreement [Member]
Debt Instrument [Line Items]
Expected Debt Issuance (minimum)		8,000,000,000
Expected Equity Issuance (maximum)		1,200,000,000
Alabama Power [Member]
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support		810,000,000
Amount of Fixed Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support		167,000,000
Maximum Borrowing Capacity		1,340,000,000
Remaining Borrowing Capacity		1,340,000,000
Alabama Power [Member] | Series FF [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.20%
Alabama Power [Member] | Senior Notes [Member] | Series 2016A [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage	4.30%
Alabama Power [Member] | Unsecured Debt [Member] | Series FF [Member]
Debt Instrument [Line Items]
Redemption Amount Of Principal Notes	$ 200,000,000
Alabama Power [Member] | Bank Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 45,000,000
Debt Instrument, Interest Rate, Stated Percentage		2.38%
Georgia Power [Member]
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support		$ 868,000,000
Amount of Fixed Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support		69,000,000
Maximum Borrowing Capacity		1,750,000,000
Remaining Borrowing Capacity		1,732,000,000
Georgia Power [Member] | Senior Notes [Member] | Series 2016A [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 325,000,000
Debt Instrument, Interest Rate, Stated Percentage		3.25%
Georgia Power [Member] | Senior Notes [Member] | Series 2016B [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 325,000,000
Debt Instrument, Interest Rate, Stated Percentage		2.40%
Georgia Power [Member] | Unsecured Debt [Member] | Series 2013B [Member]
Debt Instrument [Line Items]
Redemption Amount Of Principal Notes		$ 250,000,000
Gulf Power [Member]
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support		82,000,000
Amount of Fixed Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support		33,000,000
Maximum Borrowing Capacity		280,000,000
Remaining Borrowing Capacity		280,000,000
Mississippi Power [Member]
Debt Instrument [Line Items]
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support		40,000,000
Maximum Borrowing Capacity		205,000,000
Line of Credit Facility, Current Borrowing Capacity		100,000,000	$ 50,000,000		$ 50,000,000	$ 100,000,000
Promissory Note	$ 275,000,000
Remaining Borrowing Capacity		180,000,000
Mississippi Power [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Redemption Amount Of Principal Notes				$ 300,000,000
Mississippi Power [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity				1,200,000,000
Line of Credit Facility, Current Borrowing Capacity				900,000,000
Remaining Borrowing Capacity				300,000,000
Mississippi Power [Member] | Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Redemption Amount Of Principal Notes				$ 900,000,000
Mississippi Power [Member] | Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		10,000,000
Traditional Operating Companies [Member]
Debt Instrument [Line Items]
Amount of Fixed Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support		269,000,000
Southern Company [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity		2,250,000,000
Remaining Borrowing Capacity		2,250,000,000
Southern Power [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity		600,000,000
Line of Credit Facility, Current Borrowing Capacity		$ 276,000,000
Debt, Weighted Average Interest Rate		1.99%
Remaining Borrowing Capacity		$ 560,000,000
Early Repayment of Senior Debt		3,000,000
Southern Power [Member] | TRE Debt Due 2036 [Member]
Debt Instrument [Line Items]
Promissory Note		2,000,000
Southern Power [Member] | Project Credit Facilities [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity		413,000,000
Line of Credit Facility, Current Borrowing Capacity		$ 413,000,000
Debt, Weighted Average Interest Rate		1.99%
Line of Credit Facility, Average Amount Outstanding		$ 260,000,000
Southern Power [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity		149,000,000
Line of Credit Facility, Current Borrowing Capacity		8,000,000
Remaining Borrowing Capacity		$ 74,000,000

Retirement Benefits (Details)

Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Plans [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	$ 62	$ 64
Interest cost	100	111
Expected return on plan assets	(187)	(181)
Amortization:
Prior service costs	4	6
Net (gain)/loss	38	54
Net cost	17	54
Pension Plans [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	14	15
Interest cost	24	26
Expected return on plan assets	(46)	(45)
Amortization:
Prior service costs	1	2
Net (gain)/loss	10	14
Net cost	3	12
Pension Plans [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	17	18
Interest cost	34	38
Expected return on plan assets	(64)	(63)
Amortization:
Prior service costs	1	3
Net (gain)/loss	14	19
Net cost	2	15
Pension Plans [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	3
Interest cost	5	5
Expected return on plan assets	(9)	(8)
Amortization:
Prior service costs	0	0
Net (gain)/loss	2	3
Net cost	1	3
Pension Plans [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	3	3
Interest cost	5	5
Expected return on plan assets	(9)	(8)
Amortization:
Prior service costs	0	0
Net (gain)/loss	2	3
Net cost	1	3
Other Postretirement Benefits [Member] | Southern Company [Member]
Pension Plans and Postretirement Plans
Service cost	5	6
Interest cost	18	19
Expected return on plan assets	(14)	(15)
Amortization:
Prior service costs	2	1
Net (gain)/loss	3	5
Net cost	14	16
Other Postretirement Benefits [Member] | Alabama Power [Member]
Pension Plans and Postretirement Plans
Service cost	1	1
Interest cost	5	5
Expected return on plan assets	(6)	(6)
Amortization:
Prior service costs	1	1
Net (gain)/loss	0	0
Net cost	1	1
Other Postretirement Benefits [Member] | Georgia Power [Member]
Pension Plans and Postretirement Plans
Service cost	2	2
Interest cost	8	8
Expected return on plan assets	(6)	(6)
Amortization:
Prior service costs	0	0
Net (gain)/loss	2	3
Net cost	6	7
Other Postretirement Benefits [Member] | Gulf Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	0
Interest cost	1	1
Expected return on plan assets	0	0
Amortization:
Prior service costs	0	0
Net (gain)/loss	0	0
Net cost	1	1
Other Postretirement Benefits [Member] | Mississippi Power [Member]
Pension Plans and Postretirement Plans
Service cost	0	0
Interest cost	1	1
Expected return on plan assets	0	0
Amortization:
Prior service costs	0	0
Net (gain)/loss	0	0
Net cost	$ 1	$ 1

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Income Tax Contingency [Line Items]
Effective tax rate	30.80%	34.30%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of December 31, 2015	$ 433
Tax positions from current periods	5
Balance as of March 31, 2016	438
Tax positions impacting the effective tax rate	15		$ 10
Tax positions not impacting the effective tax rate	423		423
Kemper IGCC [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of March 31, 2016	423
Unrecognized tax benefit, associated interest	$ 12
Mississippi Power [Member]
Income Tax Contingency [Line Items]
Effective tax rate	(838.70%)	10.00%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of December 31, 2015	$ 421
Tax positions from current periods	0
Balance as of March 31, 2016	421
Tax positions impacting the effective tax rate	(2)
Tax positions not impacting the effective tax rate	423
Mississippi Power [Member] | Kemper IGCC [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of March 31, 2016	423
Unrecognized tax benefit, associated interest	12
Southern Power [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards	$ 694		$ 551
Effective tax rate	(84.00%)	25.80%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of December 31, 2015	$ 8
Tax positions from current periods	5
Balance as of March 31, 2016	13
Tax positions impacting the effective tax rate	13
Tax positions not impacting the effective tax rate	$ 0

Derivatives - Schedule of Deriv

Derivatives - Schedule of Derivatives and Gains (Losses) (Details) BTU in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)BTU
Notional amount of interest rate derivatives
Notional Amount	$ 4,657
Fair Value Gain (Loss) at March 31, 2016	(161)
Southern Company [Member] | Maturity Date November 2026 [Member] | Cash Flow Hedges Of Forecasted Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 1,500
Weighted Average Interest Rate Paid	2.14%
Fair Value Gain (Loss) at March 31, 2016	$ (55)
Southern Company [Member] | Maturity Date November 2046 [Member] | Cash Flow Hedges Of Forecasted Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 1,200
Weighted Average Interest Rate Paid	2.60%
Fair Value Gain (Loss) at March 31, 2016	$ (127)
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 March 31, 2016	$ 1
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 March 31, 2016	$ 10
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	235
Longest Hedge Date	2,020
Longest Non-Hedge Date	2,017
Alabama Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	60
Longest Hedge Date	2,019
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 March 31, 2016	$ 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 March 31, 2016	$ 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 March 31, 2016	$ 6
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] | Maturity Date December 2018 [Member] | Fair Value Hedges Of Existing Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 500
Interest Rate Received	1.95%
Fair Value Gain (Loss) at March 31, 2016	$ 5
Georgia Power [Member] | Maturity Date December 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	0.76%
Georgia Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	65
Longest Hedge Date	2,019
Gulf Power [Member] | Maturity Date December 2026 [Member] | Cash Flow Hedges Of Forecasted Debt [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 80
Weighted Average Interest Rate Paid	2.32%
Fair Value Gain (Loss) at March 31, 2016	$ (4)
Gulf Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	74
Longest Hedge Date	2,020
Mississippi Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	28
Longest Hedge Date	2,018
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 March 31, 2016	$ 0
Derivative, Term of Contract	15 years
Southern Power [Member] | Maturity Date November 2016 [Member] | Not Designated as Hedging Instrument [Member]
Notional amount of interest rate derivatives
Derivative, Term of Contract	12 years
Southern Power [Member] | Gas [Member]
Energy-related derivative contracts
Net Purchased mmBtu | BTU	8
Longest Hedge Date	2,016
Longest Non-Hedge Date	2,017
RE Roserock Holdings, LLC [Member] | Southern Power [Member] | Maturity Date October 2016 [Member] | Not Designated as Hedging Instrument [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 47
Weighted Average Interest Rate Paid	2.21%
Fair Value Gain (Loss) at March 31, 2016	$ 0
RE Garland and Garland A Holdings, LLC [Member] | Southern Power [Member] | Maturity Date November 2016 [Member] | Not Designated as Hedging Instrument [Member]
Notional amount of interest rate derivatives
Notional Amount	$ 65
Weighted Average Interest Rate Paid	2.21%
Fair Value Gain (Loss) at March 31, 2016	$ 0

Derivatives - Balance Sheet Pre

Derivatives - Balance Sheet Presentation (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Southern Company [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	$ 45	$ 29
Derivatives, liabilities	394	250
Southern Company [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	4
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	1
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	1	1
Southern Company [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	3
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	7
Derivatives, liabilities	198	217
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	3
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	5
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	124	130
Southern Company [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	74	87
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	36	22
Derivatives, liabilities	195	32
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	4	3
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	2	2
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	18	19
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	14
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	193	23
Southern Company [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		7
Alabama Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	3	1
Derivatives, liabilities	49	70
Alabama Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Alabama Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	3
Derivatives, liabilities	49	55
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	1
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	37	40
Alabama Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	12	15
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	0	15
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	15
Alabama Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Georgia Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	18	7
Derivatives, liabilities	11	21
Georgia Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Georgia Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	4
Derivatives, liabilities	11	15
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	2
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	3
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	9	12
Georgia Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	2	3
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	14	5
Derivatives, liabilities	0	6
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	7	5
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	7
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Georgia Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		6
Gulf Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	1
Derivatives, liabilities	99	100
Gulf Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Gulf Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Derivatives, liabilities	94	100
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	49	49
Gulf Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	45	51
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	1
Derivatives, liabilities	5	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	1
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	5	0
Gulf Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Mississippi Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	44	47
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
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	0
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Mississippi Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Derivatives, liabilities	44	47
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	29	29
Mississippi Power [Member] | Hedging Instruments for Regulatory Purposes [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	15	18
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Derivatives, liabilities	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	0	0
Mississippi Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		0
Southern Power [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	6	7
Derivatives, liabilities	3	3
Southern Power [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	2	4
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	1
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	1	1
Southern Power [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	1	3
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	4	3
Derivatives, liabilities	2	2
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	4	3
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	2	2
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred charges and assets [Member]
Derivatives, Fair Value [Line Items]
Derivatives, assets	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Liabilities from risk management activities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities	$ 0	0
Southern Power [Member] | Cash Flow and Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other deferred credits and liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives, liabilities		$ 0

Derivatives - Balance Sheet Off

Derivatives - Balance Sheet Offsetting (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Southern Company [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	$ 45	$ 29
Derivatives presented in the Balance Sheet, liabilities	394	250
Southern Company [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	2	1
Net interest rate derivative liabilities	191	214
Southern Company [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	12	7
Derivatives presented in the Balance Sheet, liabilities	201	220
Southern Company [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	(10)	(6)
Gross amounts not offset in the Balance Sheet, liabilities	(10)	(6)
Southern Company [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	12	13
Net interest rate derivative liabilities	172	21
Southern Company [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	33	22
Derivatives presented in the Balance Sheet, liabilities	193	30
Southern Company [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	(21)	(9)
Gross amounts not offset in the Balance Sheet, liabilities	(21)	(9)
Alabama Power [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	3	1
Derivatives presented in the Balance Sheet, liabilities	49	70
Alabama Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	46	54
Alabama Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	3	1
Derivatives presented in the Balance Sheet, liabilities	49	55
Alabama Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	(3)	(1)
Gross amounts not offset in the Balance Sheet, liabilities	(3)	(1)
Alabama Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	0	15
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	0	15
Alabama Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	0	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	18	7
Derivatives presented in the Balance Sheet, liabilities	11	21
Georgia Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	1	0
Net interest rate derivative liabilities	8	13
Georgia Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	4	2
Derivatives presented in the Balance Sheet, liabilities	11	15
Georgia Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	(3)	(2)
Gross amounts not offset in the Balance Sheet, liabilities	(3)	(2)
Georgia Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	14	1
Net interest rate derivative liabilities	0	2
Georgia Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	14	5
Derivatives presented in the Balance Sheet, liabilities	0	6
Georgia Power [Member] | Interest Rate Contract [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	0	(4)
Gross amounts not offset in the Balance Sheet, liabilities	0	(4)
Gulf Power [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	1
Derivatives presented in the Balance Sheet, liabilities	99	100
Gulf Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	94	100
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	100
Gulf Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	0	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	1
Net interest rate derivative liabilities	5	0
Gulf Power [Member] | Interest Rate Contract [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	0	1
Derivatives presented in the Balance Sheet, liabilities	5	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	44	47
Mississippi Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	0	0
Net interest rate derivative liabilities	44	47
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	44	47
Mississippi Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	0	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	6	7
Derivatives presented in the Balance Sheet, liabilities	3	3
Southern Power [Member] | Energy Related Derivative [Member]
Derivative [Line Items]
Net derivative assets	3	3
Net interest rate derivative liabilities	1	2
Southern Power [Member] | Energy Related Derivative [Member] | Net Amount Of Derivatives [Member]
Derivative [Line Items]
Derivatives presented in the Balance Sheet, assets	5	4
Derivatives presented in the Balance Sheet, liabilities	3	3
Southern Power [Member] | Energy Related Derivative [Member] | Gross Amount Of Derivatives [Member]
Derivative [Line Items]
Gross amounts not offset in the Balance Sheet, assets	(2)	(1)
Gross amounts not offset in the Balance Sheet, liabilities	(2)	(1)
Southern Power [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Net derivative assets	1	4
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	4
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
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Southern Company [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	$ (191)		$ (214)
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	(124)		(130)
Southern Company [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(74)		(87)
Southern Company [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	2		3
Southern Company [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	5
Southern Company [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(190)	$ (29)
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)	(3)	(2)
Alabama Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(46)		(54)
Alabama Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(37)		(40)
Alabama Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(12)		(15)
Alabama Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	1		1
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	2
Alabama Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(4)	(6)
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)
Georgia Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(7)		(13)
Georgia Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(9)		(12)
Georgia Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(2)		(3)
Georgia Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	1		2
Georgia Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	3
Georgia Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	(23)
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)
Gulf Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(94)		(100)
Gulf Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(49)		(49)
Gulf Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(45)		(51)
Gulf Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	0		0
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
Gulf Power [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	(5)	0
Gulf Power [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	0	$ 0
Mississippi Power [Member] | Energy Related Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(44)		(47)
Mississippi Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(29)		(29)
Mississippi Power [Member] | Energy Related Derivative [Member] | Other regulatory assets, deferred [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	(15)		(18)
Mississippi Power [Member] | Energy Related Derivative [Member] | Other regulatory liabilities, current [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Regulatory Hedge Unrealized Gain (Loss) Recognized on the Balance Sheet	0		$ 0
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

Derivatives - Pre-tax Effects49

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
	Mar. 31, 2016	Mar. 31, 2015
Southern Company [Member]
Derivative [Line Items]
Gain (Loss)	$ 20	$ 7
Georgia Power [Member]
Derivative [Line Items]
Gain (Loss)	$ 14	$ 6

Derivatives - Narrative (Detail

Derivatives - Narrative (Details) BTU in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)BTU
Derivative [Line Items]
Maximum Potential Collateral Requirements Arising from Credit Risk Related Contingent Features | $	$ 49
Southern Company [Member]
Derivative [Line Items]
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | BTU	4

Acquisitions - Schedule of Acqu

Acquisitions - Schedule of Acquisitions (Details) $ in Millions	Apr. 08, 2016USD ($)MW	Feb. 11, 2016USD ($)MW	Dec. 31, 2016USD ($)MW	Jun. 30, 2016USD ($)MW	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Construction work in progress					$ 9,406	$ 9,082
Southern Power [Member]
Business Acquisition [Line Items]
Construction work in progress					1,535	1,137
Business Combination, Contingent Consideration, Liability					21	$ 36
Southern Power [Member] | 70SM1 8ME, LCC (Calipatria) [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW		20
Southern Power Percentage Ownership		90.00%
PPA Contract Period		20 years
Approx. Purchase Price		$ 51
Southern Power [Member] | East Pecos [Member]
Business Acquisition [Line Items]
Construction work in progress					41
Southern Power [Member] | East Pecos [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Future Construction Payments					200
Southern Power [Member] | East Pecos [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Future Construction Payments					220
Southern Power [Member] | Turner Renewable Energy [Member]
Business Acquisition [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share		10.00%
Southern Power and Turner Renewable Energy [Member] | 70SM1 8ME, LCC (Calipatria) [Member]
Business Acquisition [Line Items]
Approx. Purchase Price		$ 57
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment					58
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable					2
Business Combination, Contingent Consideration, Liability		$ 6
Scenario, Forecast [Member] | 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	$ 258
Scenario, Forecast [Member] | Southern Power [Member] | East Pecos [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW			120
Southern Power Percentage Ownership			100.00%
PPA Contract Period			15 years
Approx. Purchase Price			$ 41
Scenario, Forecast [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW				40
Southern Power Percentage Ownership				100.00%
PPA Contract Period				15 years
Approx. Purchase Price				$ 127
Property, Plant and Equipment [Member] | Southern Power and Turner Renewable Energy [Member] | 70SM1 8ME, LCC (Calipatria) [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets					$ 1
Subsequent Event [Member] | Southern Power [Member] | Grant Wind, LLC [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability	$ 23
Period Of Operation For Performance Testing And Production	10 years

Acquisitions - Schedule of Cons

Acquisitions - Schedule of Construction Projects (Details) $ in Millions	3 Months Ended		10 Months Ended
	Dec. 31, 2016USD ($)MW	Sep. 30, 2016MW	Sep. 30, 2016USD ($)MW	May. 05, 2016MW	Mar. 31, 2016MW	Mar. 29, 2016	Dec. 31, 2015MW
Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Capacity Of Small Power Production Facility | MW					76		110
Southern Power Percentage Ownership						15.00%
Class A Membership Interest [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Percentage Of Entitled Cash Distributions						66.00%
Class A Membership Interest [Member] | Southern Power [Member] | Tranquillity, Roserock, Garland and Garland A [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership					100.00%
Percentage Of Entitled Cash Distributions					51.00%
Class B Membership Interest [Member] | First Solar [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Percentage Of Entitled Cash Distributions						34.00%
Class B Membership Interest [Member] | First Solar [Member] | Tranquillity, Roserock, Garland and Garland A [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership					100.00%
Class B Membership Interest [Member] | Recurrent Energy [Member] | Tranquillity, Roserock, Garland and Garland A [Member]
Business Acquisition [Line Items]
Percentage Of Entitled Cash Distributions					49.00%
Scenario, Forecast [Member] | Southern Power [Member] | Sandhills [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	146
PPA Contract Period	25 years
Scenario, Forecast [Member] | Southern Power [Member] | Sandhills [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 260
Scenario, Forecast [Member] | Southern Power [Member] | Sandhills [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 280
Scenario, Forecast [Member] | Southern Power [Member] | Butler Solar LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	103
PPA Contract Period	30 years
Scenario, Forecast [Member] | Southern Power [Member] | Butler Solar LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 220
Scenario, Forecast [Member] | Southern Power [Member] | Butler Solar LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 230
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
PPA Contract Period	15 years
Scenario, Forecast [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	205
PPA Contract Period	18 years
Scenario, Forecast [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 473
Scenario, Forecast [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 493
Scenario, Forecast [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Capacity Of Small Power Production Facility | MW		75	75
Approx. Nameplate Capacity, Solar (MW) | MW		299	299
PPA Contract Period			20 years
Scenario, Forecast [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs			$ 1,200
Scenario, Forecast [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs			$ 1,300
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	205
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 532
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 552
Scenario, Forecast [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	160
PPA Contract Period	20 years
Scenario, Forecast [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 333
Scenario, Forecast [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 353
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
PPA Contract Period		20 years
Subsequent Event [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Capacity Of Small Power Production Facility | MW				38

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - USD ($)	Feb. 24, 2016	Aug. 23, 2015	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015
Business Acquisition [Line Items]
Maximum Borrowing Capacity			$ 6,495,000,000
Construction in Progress, Gross			9,406,000,000	$ 9,082,000,000
Bridge Agreement [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs			20,000,000
Maximum Borrowing Capacity					$ 8,100,000,000
Scenario, Plan [Member] | PowerSecure International, Inc. [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	$ 431,000,000
Business Acquisition, Share Price	$ 18.75
Scenario, Plan [Member] | Bridge Agreement [Member]
Business Acquisition [Line Items]
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
Southern Power [Member]
Business Acquisition [Line Items]
Maximum Borrowing Capacity			600,000,000
Total Cost			2,200,000,000
Construction in Progress, Gross			1,535,000,000	$ 1,137,000,000
Operating Expense [Member] | Bridge Agreement [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs			6,000,000
Other Income Expense Net [Member] | Bridge Agreement [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs			$ 14,000,000

Segment and Related Informati54

Segment and Related Information - Financial Data for Business Segments (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)state	Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of States in which Entity Operates | state	4
Operating revenues	$ 3,965	$ 4,183
Segment net income (loss)	485	508
Total assets	78,735		$ 78,318
Kemper IGCC [Member]
Segment Reporting Information [Line Items]
Pre-Tax Charge To Income	53	9
After Tax Charge To Income	33	6
Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	3,954	4,172
Segment net income (loss)	514	510
Total assets	77,843		77,560
Intersegment Eliminations [Member] | Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	(103)	(124)
Segment net income (loss)	0	0
Total assets	(396)		(397)
Consolidation Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	(36)	(29)
Segment net income (loss)	(3)	(5)
Total assets	(1,178)		(1,061)
Traditional Operating Companies [Member] | Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	3,742	3,948
Segment net income (loss)	464	477
Total assets	69,240		69,052
Southern Power [Member]
Segment Reporting Information [Line Items]
Operating revenues	97	114
Southern Power [Member] | Electric Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	315	348
Segment net income (loss)	50	33
Total assets	8,999		8,905
All Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	47	40
Segment net income (loss)	(26)	$ 3
Total assets	$ 2,070		$ 1,819

Segment and Related Informati55

Segment and Related Information - Financial Data for Products and Services (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	$ 3,954	$ 4,172
Retail [Member]
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	3,377	3,542
Wholesale [Member]
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	396	467
Other [Member]
Revenue from External Customer [Line Items]
Electric Utilities' Revenues	$ 181	$ 163