Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 1,094	$ 1,975
Receivables —
Customer accounts receivable	1,560	1,565
Energy marketing receivable	493	623
Unbilled revenues	589	706
Under recovered regulatory clause revenues	47	18
Income taxes receivable, current	544	544
Other accounts and notes receivable	433	377
Accumulated provision for uncollectible accounts	(53)	(43)
Fossil fuel for generation	687	689
Materials and supplies	1,477	1,462
Natural gas for sale	346	631
Prepaid expenses	401	364
Other regulatory assets, current	560	581
Other current assets	249	230
Total current assets	8,427	9,722
Property, Plant, and Equipment:
In service	99,774	98,416
Less: Accumulated depreciation	30,330	29,852
Plant in service, net of depreciation	69,444	68,564
Nuclear fuel, at amortized cost	902	905
Construction work in progress	9,465	8,977
Total property, plant, and equipment	79,811	78,446
Other Property and Investments:
Goodwill	6,251	6,251
Equity investments in unconsolidated subsidiaries	1,615	1,549
Other intangible assets, net of amortization	935	970
Nuclear decommissioning trusts, at fair value	1,678	1,606
Leveraged leases	780	774
Miscellaneous property and investments	293	270
Total other property and investments	11,552	11,420
Deferred Charges and Other Assets:
Deferred charges related to income taxes	1,647	1,629
Unamortized loss on reacquired debt	218	223
Other regulatory assets, deferred	6,748	6,851
Other deferred charges and assets	1,357	1,406
Total deferred charges and other assets	9,970	10,109
Total Assets	109,760	109,697
Current Liabilities:
Securities due within one year	3,269	2,587
Notes payable	2,818	2,241
Energy marketing trade payables	471	597
Accounts payable —
Accounts payable	1,750	2,228
Customer deposits	541	558
Accrued taxes —
Accrued income taxes	258	193
Other accrued taxes	326	667
Unrecognized tax benefits	400	385
Accrued interest	453	518
Accrued compensation	461	915
Asset retirement obligations, current	386	378
Liabilities from risk management activities, net of collateral	63	107
Acquisitions payable	0	489
Other regulatory liabilities, current	221	236
Other current liabilities	867	818
Total current liabilities	12,284	12,917
Long-term Debt:
Long-term Debt	42,786	42,629
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	14,307	14,092
Deferred credits related to income taxes	215	219
Accumulated deferred investment tax credits	2,264	2,228
Employee benefit obligations	2,234	2,299
Asset retirement obligations, deferred	4,170	4,136
Accrued environmental remediation	388	397
Other cost of removal obligations	2,724	2,748
Other regulatory liabilities, deferred	237	258
Other deferred credits and liabilities	873	880
Total deferred credits and other liabilities	27,412	27,257
Total Liabilities	82,482	82,803
Redeemable Preferred Stock of Subsidiaries	118	118
Redeemable Noncontrolling Interests	164	164
Common Stockholders' Equity:
Par value	4,973	4,952
Paid-in capital	9,884	9,661
Treasury, at cost	(33)	(31)
Retained earnings (accumulated deficit)	10,459	10,356
Accumulated other comprehensive loss	(189)	(180)
Total Common Stockholders' Equity	25,094	24,758
Preferred and Preference Stock of Subsidiaries	609	609
Noncontrolling Interests	1,293	1,245
Total Stockholders' Equity	26,996	26,612
Total Liabilities and Stockholders' Equity	109,760	109,697
Alabama Power [Member]
Current Assets:
Cash and cash equivalents	696	420
Receivables —
Customer accounts receivable	326	348
Unbilled revenues	127	146
Other accounts and notes receivable	31	27
Affiliated	35	40
Accumulated provision for uncollectible accounts	(10)	(10)
Fossil fuel for generation	195	205
Materials and supplies	444	435
Prepaid expenses	106	34
Other regulatory assets, current	141	149
Other current assets	8	11
Total current assets	2,099	1,805
Property, Plant, and Equipment:
In service	26,134	26,031
Less: Accumulated depreciation	9,241	9,112
Plant in service, net of depreciation	16,893	16,919
Nuclear fuel, at amortized cost	332	336
Construction work in progress	642	491
Total property, plant, and equipment	17,867	17,746
Other Property and Investments:
Equity investments in unconsolidated subsidiaries	65	66
Nuclear decommissioning trusts, at fair value	825	792
Miscellaneous property and investments	113	112
Total other property and investments	1,003	970
Deferred Charges and Other Assets:
Deferred charges related to income taxes	526	525
Deferred under recovered regulatory clause revenues	0	150
Other regulatory assets, deferred	1,218	1,157
Other deferred charges and assets	156	163
Total deferred charges and other assets	1,900	1,995
Total Assets	22,869	22,516
Current Liabilities:
Securities due within one year	361	561
Accounts payable —
Affiliated	224	297
Other	232	433
Customer deposits	90	88
Accrued taxes —
Accrued income taxes	95	45
Other accrued taxes	65	42
Accrued interest	65	78
Accrued compensation	95	193
Other regulatory liabilities, current	45	85
Other current liabilities	71	76
Total current liabilities	1,343	1,898
Long-term Debt:
Long-term Debt	7,081	6,535
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	4,714	4,654
Deferred credits related to income taxes	65	65
Accumulated deferred investment tax credits	108	110
Employee benefit obligations	288	300
Asset retirement obligations, deferred	1,523	1,503
Other cost of removal obligations	667	684
Other regulatory liabilities, deferred	88	100
Other deferred credits and liabilities	70	63
Total deferred credits and other liabilities	7,523	7,479
Total Liabilities	15,947	15,912
Redeemable Preferred Stock	85	85
Preference Stock	196	196
Common Stockholders' Equity:
Par value	1,222	1,222
Paid-in capital	2,936	2,613
Retained earnings (accumulated deficit)	2,513	2,518
Accumulated other comprehensive loss	(30)	(30)
Total Common Stockholders' Equity	6,641	6,323
Total Liabilities and Stockholders' Equity	22,869	22,516
Georgia Power [Member]
Current Assets:
Cash and cash equivalents	21	3
Receivables —
Customer accounts receivable	470	523
Unbilled revenues	200	224
Joint owner accounts receivable	146	57
Other accounts and notes receivable	57	81
Affiliated	12	18
Accumulated provision for uncollectible accounts	(3)	(3)
Fossil fuel for generation	336	298
Materials and supplies	474	479
Prepaid expenses	35	105
Other regulatory assets, current	195	193
Other current assets	38	38
Total current assets	1,981	2,016
Property, Plant, and Equipment:
In service	34,059	33,841
Less: Accumulated depreciation	11,443	11,317
Plant in service, net of depreciation	22,616	22,524
Nuclear fuel, at amortized cost	570	569
Construction work in progress	5,183	4,939
Total property, plant, and equipment	28,369	28,032
Other Property and Investments:
Equity investments in unconsolidated subsidiaries	58	60
Nuclear decommissioning trusts, at fair value	853	814
Miscellaneous property and investments	46	46
Total other property and investments	957	920
Deferred Charges and Other Assets:
Deferred charges related to income taxes	676	676
Other regulatory assets, deferred	2,792	2,774
Other deferred charges and assets	473	417
Total deferred charges and other assets	3,941	3,867
Total Assets	35,248	34,835
Current Liabilities:
Securities due within one year	488	460
Notes payable	0	391
Accounts payable —
Affiliated	347	438
Other	657	589
Customer deposits	268	265
Accrued taxes —
Accrued income taxes	56	17
Other accrued taxes	115	390
Accrued interest	115	106
Accrued compensation	110	224
Asset retirement obligations, current	305	299
Other current liabilities	241	297
Total current liabilities	2,702	3,476
Long-term Debt:
Long-term Debt	11,042	10,225
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	6,073	6,000
Deferred credits related to income taxes	119	121
Accumulated deferred investment tax credits	253	256
Employee benefit obligations	673	703
Asset retirement obligations, deferred	2,256	2,233
Other deferred credits and liabilities	214	199
Total deferred credits and other liabilities	9,588	9,512
Total Liabilities	23,332	23,213
Redeemable Preferred Stock	45	45
Preference Stock	221	221
Common Stockholders' Equity:
Par value	398	398
Paid-in capital	7,238	6,885
Retained earnings (accumulated deficit)	4,026	4,086
Accumulated other comprehensive loss	(12)	(13)
Total Common Stockholders' Equity	11,650	11,356
Total Liabilities and Stockholders' Equity	35,248	34,835
Gulf Power [Member]
Current Assets:
Cash and cash equivalents	32	56
Receivables —
Customer accounts receivable	58	72
Unbilled revenues	52	55
Under recovered regulatory clause revenues	47	17
Other accounts and notes receivable	9	6
Affiliated	28	17
Accumulated provision for uncollectible accounts	(1)	(1)
Fossil fuel for generation	59	71
Materials and supplies	56	55
Other regulatory assets, current	50	44
Other current assets	22	30
Total current assets	412	422
Property, Plant, and Equipment:
In service	5,110	5,140
Less: Accumulated depreciation	1,401	1,382
Plant in service, net of depreciation	3,709	3,758
Construction work in progress	67	51
Total property, plant, and equipment	3,776	3,809
Deferred Charges and Other Assets:
Deferred charges related to income taxes	57	58
Other regulatory assets, deferred	501	512
Other deferred charges and assets	21	21
Total deferred charges and other assets	579	591
Total Assets	4,767	4,822
Current Liabilities:
Securities due within one year	92	87
Notes payable	100	268
Accounts payable —
Affiliated	47	59
Other	47	54
Customer deposits	35	35
Accrued taxes —
Other accrued taxes	16	20
Accrued interest	18	8
Accrued compensation	17	40
Deferred capacity expense, current	22	22
Asset retirement obligations, current	32	16
Other regulatory liabilities, current	5	16
Other current liabilities	30	24
Total current liabilities	461	649
Long-term Debt:
Long-term Debt	987	987
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	952	948
Employee benefit obligations	94	96
Deferred capacity expense	114	119
Asset retirement obligations, deferred	106	120
Other cost of removal obligations	226	249
Other regulatory liabilities, deferred	48	47
Other deferred credits and liabilities	78	71
Total deferred credits and other liabilities	1,618	1,650
Total Liabilities	3,066	3,286
Preference Stock	147	147
Common Stockholders' Equity:
Par value	678	503
Paid-in capital	594	589
Retained earnings (accumulated deficit)	282	296
Accumulated other comprehensive loss	0	1
Total Common Stockholders' Equity	1,554	1,389
Total Liabilities and Stockholders' Equity	4,767	4,822
Mississippi Power [Member]
Current Assets:
Cash and cash equivalents	6	224
Receivables —
Customer accounts receivable	26	29
Unbilled revenues	38	42
Income taxes receivable, current	544	544
Other accounts and notes receivable	17	14
Affiliated	14	15
Fossil fuel for generation	83	100
Materials and supplies	78	76
Other regulatory assets, current	113	115
Other current assets	3	8
Total current assets	922	1,167
Property, Plant, and Equipment:
In service	4,963	4,865
Less: Accumulated depreciation	1,303	1,289
Plant in service, net of depreciation	3,660	3,576
Construction work in progress	2,570	2,545
Total property, plant, and equipment	6,230	6,121
Other Property and Investments:
Total other property and investments	12	12
Deferred Charges and Other Assets:
Deferred charges related to income taxes	382	361
Other regulatory assets, deferred	520	518
Other deferred charges and assets	22	56
Total deferred charges and other assets	924	935
Total Assets	8,088	8,235
Current Liabilities:
Securities due within one year - parent	0	551
Securities due within one year	1,328	78
Notes payable	36	23
Accounts payable —
Affiliated	44	62
Other	112	135
Customer deposits	16	16
Accrued taxes —
Other accrued taxes	51	99
Unrecognized tax benefits	385	383
Accrued interest	50	46
Accrued compensation	20	42
Asset retirement obligations, current	27	32
Over recovered regulatory clause liabilities	39	51
Other current liabilities	22	20
Total current liabilities	2,130	1,538
Long-term Debt:
Long-term debt to parent	551	0
Long-term debt, non-affiliated	1,172	2,424
Long-term Debt	1,723	2,424
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	729	756
Employee benefit obligations	113	115
Asset retirement obligations, deferred	148	146
Other cost of removal obligations	172	170
Other regulatory liabilities, deferred	78	84
Other deferred credits and liabilities	36	26
Total deferred credits and other liabilities	1,276	1,297
Total Liabilities	5,129	5,259
Redeemable Preferred Stock	33	33
Common Stockholders' Equity:
Par value	38	38
Paid-in capital	3,526	3,525
Retained earnings (accumulated deficit)	(635)	(616)
Accumulated other comprehensive loss	(3)	(4)
Total Common Stockholders' Equity	2,926	2,943
Total Liabilities and Stockholders' Equity	8,088	8,235
Southern Power [Member]
Current Assets:
Cash and cash equivalents	93	1,099
Receivables —
Customer accounts receivable	111	102
Other accounts and notes receivable	32	34
Affiliated	62	57
Fossil fuel for generation	14	15
Materials and supplies	343	337
Prepaid income taxes	95	74
Other current assets	31	39
Total current assets	781	1,757
Property, Plant, and Equipment:
In service	13,493	12,728
Less: Accumulated depreciation	1,598	1,484
Plant in service, net of depreciation	11,895	11,244
Construction work in progress	328	398
Total property, plant, and equipment	12,223	11,642
Other Property and Investments:
Goodwill	2	2
Intangible assets, net (including goodwill)	430	436
Total other property and investments	430	436
Deferred Charges and Other Assets:
Prepaid LTSAs	120	101
Accumulated deferred income taxes	570	594
Other deferred charges and assets — affiliated	26	13
Other deferred charges and assets	531	626
Total deferred charges and other assets	1,247	1,334
Total Assets	14,681	15,169
Current Liabilities:
Securities due within one year	560	560
Notes payable	380	209
Accounts payable —
Affiliated	76	88
Other	129	278
Accrued taxes —
Accrued income taxes	48	148
Other accrued taxes	13	7
Accrued interest	47	36
Acquisitions payable	0	461
Contingent consideration	14	46
Other current liabilities	69	70
Total current liabilities	1,336	1,903
Long-term Debt:
Long-term Debt	5,088	5,068
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	157	152
Accumulated deferred investment tax credits	1,879	1,839
Asset retirement obligations, deferred	67	64
Other deferred credits and liabilities	288	304
Total deferred credits and other liabilities	2,391	2,359
Total Liabilities	8,815	9,330
Redeemable Noncontrolling Interests	164	164
Common Stockholders' Equity:
Par value	0	0
Paid-in capital	3,671	3,671
Retained earnings (accumulated deficit)	714	724
Accumulated other comprehensive loss	24	35
Total Common Stockholders' Equity	4,409	4,430
Noncontrolling interests	1,293	1,245
Total Stockholders' Equity	5,702	5,675
Total Liabilities and Stockholders' Equity	14,681	15,169
Southern Company Gas [Member]
Current Assets:
Cash and cash equivalents	28	19
Receivables —
Customer accounts receivable	453	364
Energy marketing receivable	493	623
Unbilled revenues	173	239
Other accounts and notes receivable	69	76
Accumulated provision for uncollectible accounts	(37)	(27)
Materials and supplies	25	26
Natural gas for sale	346	631
Prepaid expenses	54	55
Assets from risk management activities, net of collateral	138	128
Prepaid income taxes	0	24
Other regulatory assets, current	60	81
Other current assets	16	11
Total current assets	1,818	2,250
Property, Plant, and Equipment:
In service	14,660	14,508
Less: Accumulated depreciation	4,498	4,439
Plant in service, net of depreciation	10,162	10,069
Construction work in progress	625	496
Total property, plant, and equipment	10,787	10,565
Other Property and Investments:
Goodwill	5,967	5,967
Equity investments in unconsolidated subsidiaries	1,604	1,541
Other intangible assets, net of amortization	340	366
Miscellaneous property and investments	21	21
Total other property and investments	7,932	7,895
Deferred Charges and Other Assets:
Other regulatory assets, deferred	958	973
Other deferred charges and assets	188	170
Total deferred charges and other assets	1,146	1,143
Total Assets	21,683	21,853
Current Liabilities:
Securities due within one year	22	22
Notes payable	1,023	1,257
Energy marketing trade payables	471	597
Accounts payable —
Accounts payable	241	348
Customer deposits	131	153
Accrued taxes —
Accrued income taxes	50	26
Other accrued taxes	63	68
Accrued interest	59	48
Accrued compensation	43	58
Liabilities from risk management activities, net of collateral	18	62
Other regulatory liabilities, current	148	102
Accrued environmental remediation, current	66	69
Temporary LIFO liquidation	126	0
Other current liabilities	124	108
Total current liabilities	2,585	2,918
Long-term Debt:
Long-term Debt	5,246	5,259
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	2,059	1,975
Employee benefit obligations	434	441
Accrued environmental remediation	343	357
Other cost of removal obligations	1,630	1,616
Other regulatory liabilities, deferred	54	51
Other deferred credits and liabilities	88	127
Total deferred credits and other liabilities	4,608	4,567
Total Liabilities	12,439	12,744
Common Stockholders' Equity:
Par value	0	0
Paid-in capital	9,104	9,095
Retained earnings (accumulated deficit)	116	(12)
Accumulated other comprehensive loss	24	26
Total Stockholders' Equity	9,244	9,109
Total Liabilities and Stockholders' Equity	$ 21,683	$ 21,853