Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Revenues:
Retail revenues			$ 15,234	$ 14,987	$ 15,550
Wholesale electric revenues			1,926	1,798	2,184
Other electric revenues			698	657	672
Natural gas revenues			1,596	0	0
Other revenues			442	47	61
Total operating revenues			19,896	17,489	18,467
Operating Expenses:
Fuel			4,361	4,750	6,005
Purchased power			750	645	672
Cost of natural gas			613	0	0
Cost of other sales			260	0	0
Other operations and maintenance			5,240	4,416	4,354
Depreciation and amortization			2,923	2,395	2,293
Depreciation and amortization			2,502	2,034	1,945
Taxes other than income taxes			1,113	997	981
Estimated loss on Kemper IGCC			428	365	868
Total operating expenses			15,267	13,207	14,825
Operating Income			4,629	4,282	3,642
Other Income and (Expense):
Allowance for equity funds used during construction			202	226	245
Earnings from equity method investments			59	0	0
Interest expense, net of amounts capitalized			(1,317)	(840)	(835)
Other income (expense), net			(93)	(39)	(44)
Total other income and (expense)			(1,149)	(653)	(634)
Earnings Before Income Taxes			3,480	3,629	3,008
Income taxes			951	1,194	977
Consolidated Net Income			2,529	2,435	2,031
Dividends on preferred and preference stock of subsidiaries			45	54	68
Net income attributable to noncontrolling interests			36	14	0
Consolidated Net Income Attributable to Southern Company			$ 2,448	$ 2,367	$ 1,963
Earnings per share (EPS) —
Basic EPS (in dollars per share)			$ 2.57	$ 2.60	$ 2.19
Diluted EPS (in dollars per share)			$ 2.55	$ 2.59	$ 2.18
Average number of shares of common stock outstanding — (in millions)
Basic shares			951	910	897
Diluted shares			958	914	901
Alabama Power [Member]
Operating Revenues:
Retail revenues			$ 5,322	$ 5,234	$ 5,249
Wholesale revenues, non-affiliates			283	241	281
Wholesale revenues, affiliates			69	84	189
Other revenues			215	209	223
Total operating revenues			5,889	5,768	5,942
Operating Expenses:
Fuel			1,297	1,342	1,605
Purchased power, non-affiliates			166	171	185
Purchased power, affiliates			168	180	200
Other operations and maintenance			1,510	1,501	1,468
Depreciation and amortization			844	780	724
Depreciation and amortization			703	643	603
Taxes other than income taxes			380	368	356
Total operating expenses			4,224	4,205	4,417
Operating Income			1,665	1,563	1,525
Other Income and (Expense):
Allowance for equity funds used during construction			28	60	49
Interest expense, net of amounts capitalized			(302)	(274)	(255)
Other income (expense), net			(21)	(32)	(7)
Total other income and (expense)			(295)	(246)	(213)
Earnings Before Income Taxes			1,370	1,317	1,312
Income taxes			531	506	512
Consolidated Net Income			839	811	800
Dividends on preferred and preference stock of subsidiaries			17	26	39
Consolidated Net Income Attributable to Southern Company			822	785	761
Georgia Power [Member]
Operating Revenues:
Retail revenues			7,772	7,727	8,240
Wholesale revenues, non-affiliates			175	215	335
Wholesale revenues, affiliates			42	20	42
Other revenues			394	364	371
Total operating revenues			8,383	8,326	8,988
Operating Expenses:
Fuel			1,807	2,033	2,547
Purchased power, non-affiliates			361	289	287
Purchased power, affiliates			518	575	701
Other operations and maintenance			1,960	1,844	1,902
Depreciation and amortization			1,063	1,029	1,019
Depreciation and amortization			855	846	846
Taxes other than income taxes			405	391	409
Total operating expenses			5,906	5,978	6,692
Operating Income			2,477	2,348	2,296
Other Income and (Expense):
Allowance for equity funds used during construction			48	40	45
Interest expense, net of amounts capitalized			(388)	(363)	(348)
Other income (expense), net			38	61	23
Total other income and (expense)			(350)	(302)	(325)
Earnings Before Income Taxes			2,127	2,046	1,971
Income taxes			780	769	729
Consolidated Net Income			1,347	1,277	1,242
Dividends on preferred and preference stock of subsidiaries			17	17	17
Consolidated Net Income Attributable to Southern Company			1,330	1,260	1,225
Gulf Power [Member]
Operating Revenues:
Retail revenues			1,281	1,249	1,267
Wholesale revenues, non-affiliates			61	107	129
Wholesale revenues, affiliates			75	58	130
Other revenues			68	69	64
Total operating revenues			1,485	1,483	1,590
Operating Expenses:
Fuel			432	445	605
Purchased power, non-affiliates			126	100	82
Purchased power, affiliates			16	35	25
Other operations and maintenance			336	354	341
Depreciation and amortization			179	152	153
Depreciation and amortization			172	141	145
Taxes other than income taxes			120	118	111
Total operating expenses			1,202	1,193	1,309
Operating Income			283	290	281
Other Income and (Expense):
Interest expense, net of amounts capitalized			(47)	(49)	(53)
Other income (expense), net			(5)	8	9
Total other income and (expense)			(52)	(41)	(44)
Earnings Before Income Taxes			231	249	237
Income taxes			91	92	88
Consolidated Net Income			140	157	149
Dividends on preferred and preference stock of subsidiaries			9	9	9
Consolidated Net Income Attributable to Southern Company			131	148	140
Mississippi Power [Member]
Operating Revenues:
Retail revenues			859	776	795
Wholesale revenues, non-affiliates			261	270	323
Wholesale revenues, affiliates			26	76	107
Other revenues			17	16	18
Total operating revenues			1,163	1,138	1,243
Operating Expenses:
Fuel			343	443	574
Purchased power, non-affiliates			5	5	18
Purchased power, affiliates			29	7	25
Other operations and maintenance			312	274	271
Depreciation and amortization			157	126	104
Depreciation and amortization			132	123	97
Taxes other than income taxes			109	94	79
Estimated loss on Kemper IGCC			428	365	868
Total operating expenses			1,358	1,311	1,932
Operating Income			(195)	(173)	(689)
Other Income and (Expense):
Allowance for equity funds used during construction			124	110	136
Interest expense, net of amounts capitalized			(74)	(7)	(45)
Other income (expense), net			(7)	(8)	(14)
Total other income and (expense)			43	95	77
Earnings Before Income Taxes			(152)	(78)	(612)
Income taxes			(104)	(72)	(285)
Consolidated Net Income			(48)	(6)	(327)
Dividends on preferred and preference stock of subsidiaries			2	2	2
Consolidated Net Income Attributable to Southern Company			(50)	(8)	(329)
Southern Power [Member]
Operating Revenues:
Wholesale revenues, non-affiliates			1,146	964	1,116
Wholesale revenues, affiliates			419	417	383
Other revenues			12	9	2
Total operating revenues			1,577	1,390	1,501
Operating Expenses:
Fuel			456	441	596
Purchased power, non-affiliates			81	72	105
Purchased power, affiliates			21	21	66
Other operations and maintenance			354	260	237
Depreciation and amortization			370	254	225
Depreciation and amortization			352	248	220
Taxes other than income taxes			23	22	22
Total operating expenses			1,287	1,064	1,246
Operating Income			290	326	255
Other Income and (Expense):
Interest expense, net of amounts capitalized			(117)	(77)	(89)
Other income (expense), net			6	1	6
Total other income and (expense)			(111)	(76)	(83)
Earnings Before Income Taxes			179	250	172
Income taxes			(195)	21	(3)
Consolidated Net Income			374	229	175
Net income attributable to noncontrolling interests			36	14	3
Net income attributable to Southern Power Company			$ 338	215	172
Predecessor [Member] | Southern Company Gas [Member]
Operating Revenues:
Natural gas revenues		$ 1,841		3,817	5,257
Other revenues		64		124	128
Total operating revenues		1,905		3,941	5,385
Operating Expenses:
Cost of natural gas		755		1,617	2,729
Cost of other sales		14		28	36
Other operations and maintenance		454		928	939
Depreciation and amortization		206		397	380
Taxes other than income taxes		99		181	208
Merger-related expenses		56		44	0
Total operating expenses		1,584		3,195	4,292
Gain on disposition of assets		0		0	2
Operating Income		321		746	1,095
Other Income and (Expense):
Earnings from equity method investments		2		6	8
Interest expense, net of amounts capitalized		(96)		(175)	(182)
Other income (expense), net		5		9	9
Total other income and (expense)		(89)		(160)	(165)
Earnings Before Income Taxes		232		586	930
Income taxes		87		213	350
Income from continuing operations		145		373	580
Loss from discontinued operations, net of tax		0		0	80
Consolidated Net Income		145		373	500
Net income attributable to noncontrolling interests		14		20	18
Consolidated Net Income Attributable to Southern Company		$ 131		$ 353	$ 482
Successor [Member] | Southern Company Gas [Member]
Operating Revenues:
Natural gas revenues	$ 1,596
Other revenues	56
Total operating revenues	1,652
Operating Expenses:
Cost of natural gas	613
Cost of other sales	10
Other operations and maintenance	482
Depreciation and amortization	238
Taxes other than income taxes	71
Merger-related expenses	41
Total operating expenses	1,455
Gain on disposition of assets	0
Operating Income	197
Other Income and (Expense):
Earnings from equity method investments	60
Interest expense, net of amounts capitalized	(81)
Other income (expense), net	14
Total other income and (expense)	(7)
Earnings Before Income Taxes	190
Income taxes	76
Income from continuing operations	114
Loss from discontinued operations, net of tax	0
Consolidated Net Income	114
Net income attributable to noncontrolling interests	0
Consolidated Net Income Attributable to Southern Company	$ 114