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

Amortization of deferred investment tax credits.

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Cash paid received during period.

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The net change during the reporting period in the aggregate amount of construction obligations due within one year (or one business cycle). This includes accounts payable related to construction activities.

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The net change during the reporting period in the aggregate amount of construction obligations due within one year (or one business cycle) net of joint owner portion. This includes accounts payable related to construction activities.

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Customer Liability Associated With Kemper Refunds

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Estimated Loss On Integrated Coal Gasification Combined Cycle Project

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Federal Financing Bank Loan

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The cash outflow (inflow) for a financial contract that settles in the period relating to operating activities.

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The net change during the period in the amount of cash payments due to taxing authorities for income and non income-related taxes.

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Increase decrease retail fuel cost over recovery short-term.

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Increase (Decrease) in Energy Related Inventory, Natural Gas in Storage

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The cash inflow to the parent company associated with security instrument that either represents a creditor or an ownership relationship with the holder of the investment security with a maturity of beyond one year or normal operating cycle, if longer. Includes proceeds from (a) debt, (b) capital lease obligations, (c) mandatory redeemable capital securities, and (d) any combination of (a), (b), or (c).

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Long-term Debt Redemption To Parent Company

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Mirror Construction Work In Progress

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Increase or decrease in over recovered regulatory clause revenues on the cash flow.

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Payments for investment in restricted cash.

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Payments pursuant to long-term service agreements.

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Prepaid Long-Term Service Agreement

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Proceeds.

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Proceeds from capital grant.

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Proceeds From Distribution Of Restricted Cash

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Promissory Note

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Purchase of Membership Interests from Noncontrolling Interests

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Recognition of deferred expenses.

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Redemptions.

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The cash inflow from the additional capital contribution to the entity.

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The net cash inflow or outflow for borrowing having initial term of repayment within one year or the normal operating cycle, if longer.

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The cash outflow for a long-term debt where the holder has highest claim on the entity's asset in case of bankruptcy or liquidation during the period.

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The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

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