Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Summary of Significant Accounting Policies [Line Items]

Regulatory Assets and Liabilities

Regulatory assets and (liabilities) reflected in the balance sheets at December 31 relate to:

	2015			2014			Note
	(in millions)
Retiree benefit plans	$	3,440		$	3,469		(a,n)
Deferred income tax charges	1,514			1,458			(b)
Asset retirement obligations-asset	481			119			(b,n)
Other regulatory assets	299			275			(k)
Loss on reacquired debt	248			267			(c)
Fuel-hedging-asset	225			202			(d,n)
Kemper IGCC regulatory assets	216			148			(h)
Vacation pay	178			177			(f,n)
Deferred PPA charges	163			185			(e,n)
Under recovered regulatory clause revenues	142			157			(g)
Remaining net book value of retired assets	283			44			(o)
Environmental remediation-asset	78			64			(j,n)
Property damage reserves-asset	92			98			(i)
Nuclear outage	88			99			(g)
Other cost of removal obligations	(1,177		)	(1,229		)	(b)
Over recovered regulatory clause revenues	(261		)	(48		)	(g)
Deferred income tax credits	(187		)	(192		)	(b)
Property damage reserves-liability	(178		)	(181		)	(l)
Asset retirement obligations-liability	(45		)	(130		)	(b,n)
Other regulatory liabilities	(35		)	(47		)	(m)
Mirror CWIP	—			(271		)	(h)
Total regulatory assets (liabilities), net	$	5,564		$	4,664

Note: The recovery and amortization periods for these regulatory assets and (liabilities) are as follows:

(a) Recovered and amortized over the average remaining service period which may range up to 15 years. See Note 2 for additional information.

(b) Asset retirement and removal assets and liabilities are recorded, deferred income tax assets are recovered, and deferred income tax liabilities are amortized over the related property lives, which may range up to 70 years. Asset retirement and removal assets and liabilities will be settled and trued up following completion of the related activities. At December 31, 2015, other cost of removal obligations included $14 million that will be amortized over the twelve months ending December 31, 2016 in accordance with Georgia Power's 2013 ARP.

(c) Recovered over either the remaining life of the original issue or, if refinanced, over the remaining life of the new issue, which may range up to 50 years.

(d) Recorded over the life of the underlying hedged purchase contracts, which generally do not exceed five years. Upon final settlement, actual costs incurred are recovered through the energy cost recovery clause.

(e) Recovered over the life of the PPA for periods up to eight years.

(f) Recorded as earned by employees and recovered as paid, generally within one year. This includes both vacation and banked holiday pay.

(g) Recorded and recovered or amortized as approved or accepted by the appropriate state PSCs over periods not exceeding 10 years.

(h) For additional information, see Note 3 under "Integrated Coal Gasification Combined Cycle – Rate Recovery of Kemper IGCC Costs – Regulatory Assets and    Liabilities."

(i) Recorded and recovered or amortized as approved or accepted by the appropriate state PSCs over periods generally not exceeding six years.

(j) Recovered through the environmental cost recovery clause when the remediation is performed.

(k) Comprised of numerous immaterial components including deferred income tax charges - Medicare subsidy, cancelled construction projects, building leases, closure of Plant Scholz ash pond, Plant Daniel Units 3 and 4 regulatory assets, property tax, and other miscellaneous assets. These costs are recorded and recovered or amortized as approved by the appropriate state PSCs over periods generally not exceeding 15 years.

(l) Recovered as storm restoration and potential reliability-related expenses are incurred as approved by the appropriate state PSCs.

(m) Comprised of numerous immaterial components including retiree benefit plans, fuel-hedging gains, and other liabilities that are recorded and recovered or amortized as approved by the appropriate state PSCs generally over periods not exceeding 15 years.

(n) Not earning a return as offset in rate base by a corresponding asset or liability.

(o) Amortized as approved by the appropriate state PSCs over periods not exceeding 11 years.

Property Plant and Equipment

The Southern Company system's property, plant, and equipment in service consisted of the following at December 31:

	2015		2014
	(in millions)
Generation	$	41,648	$	37,892
Transmission	10,544		9,884
Distribution	17,670		17,123
General	4,377		4,198
Plant acquisition adjustment	123		123
Utility plant in service	74,362		69,220
Information technology equipment and software	222		244
Communications equipment	418		439
Other	116		110
Other plant in service	756		793
Total plant in service	$	75,118	$	70,013

Assets Acquired Under Capital Leases

Assets acquired under a capital lease are included in property, plant, and equipment and are further detailed in the table below:

	Asset Balances at December 31,
	2015			2014
	(in millions)
Office building	$	61		$	61
Nitrogen plant	83			83
Computer-related equipment	61			60
Gas pipeline	6			6
Less: Accumulated amortization	(59		)	(49		)
Balance, net of amortization	$	152		$	161

Asset Retirement Obligations and Other Costs of Removal

Details of the AROs included in the balance sheets are as follows:

	2015			2014
	(in millions)
Balance at beginning of year	$	2,201		$	2,018
Liabilities incurred	662			18
Liabilities settled	(37		)	(17		)
Accretion	115			102
Cash flow revisions	818			80
Balance at end of year	$	3,759		$	2,201

Accumulated Provisions for Decommissioning

At December 31, 2015 and 2014, the accumulated provisions for decommissioning were as follows:

	External Trust Funds				Internal Reserves				Total
	2015		2014		2015		2014		2015		2014
	(in millions)
Plant Farley	$	734	$	754	$	20	$	21	$	754	$	775
Plant Hatch	487		496		—		—		487		496
Plant Vogtle Units 1 and 2	288		293		—		—		288		293

Estimated Cost of Decommissioning

The estimated costs of decommissioning as of December 31, 2015 based on the most current studies, which were performed in 2013 for Alabama Power's Plant Farley and in 2015 for the Georgia Power plants, were as follows for Alabama Power's Plant Farley and Georgia Power's ownership interests in Plant Hatch and Plant Vogtle Units 1 and 2:

	Plant Farley		Plant Hatch		Plant Vogtle Units 1 and 2
Decommissioning periods:
Beginning year	2037		2034		2047
Completion year	2076		2075		2079
	(in millions)
Site study costs:
Radiated structures	$	1,362	$	678	$	568
Spent fuel management	—		160		147
Non-radiated structures	80		64		89
Total site study costs	$	1,442	$	902	$	804

Net Investments in Leveraged Leases

Southern Company's net investment in domestic and international leveraged leases consists of the following at December 31:

	2015			2014
	(in millions)
Net rentals receivable	$	1,487		$	1,495
Unearned income	(732		)	(752		)
Investment in leveraged leases	755			743
Deferred taxes from leveraged leases	(303		)	(299		)
Net investment in leveraged leases	$	452		$	444

Components of Income from Leveraged Leases

A summary of the components of income from the leveraged leases follows:

	2015			2014			2013
	(in millions)
Pretax leveraged lease income (loss)	$	20		$	24		$	(5	)
Income tax expense	(7		)	(9		)	2
Net leveraged lease income (loss)	$	13		$	15		$	(3	)

Accumulated Other Comprehensive Income (Loss) Balances, Net of Tax Effects

Accumulated OCI (loss) balances, net of tax effects, were as follows:

	Qualifying Hedges			Marketable Securities		Pension and Other Postretirement Benefit Plans			Accumulated Other Comprehensive Income (Loss)
	(in millions)
Balance at December 31, 2014	$	(41	)	$	—	$	(87	)	$	(128	)
Current period change	(7		)	—		5			(2		)
Balance at December 31, 2015	$	(48	)	$	—	$	(82	)	$	(130	)

Alabama Power [Member]

Summary of Significant Accounting Policies [Line Items]

Regulatory Assets and Liabilities

Regulatory assets and (liabilities) reflected in the balance sheets at December 31 relate to:

	2015			2014			Note
	(in millions)
Deferred income tax charges	$	522		$	525		(a,k)
Loss on reacquired debt	75			80			(b)
Vacation pay	66			65			(c,j)
Under/(over) recovered regulatory clause revenues	(97		)	57			(d)
Fuel-hedging losses	55			53			(e,j)
Other regulatory assets	53			49			(f)
Asset retirement obligations	(40		)	(125		)	(a)
Other cost of removal obligations	(722		)	(744		)	(a)
Deferred income tax credits	(70		)	(72		)	(a)
Nuclear outage	53			56			(d)
Natural disaster reserve	(75		)	(84		)	(h)
Other regulatory liabilities	(8		)	(17		)	(e,g)
Retiree benefit plans	903			882			(i,j)
Remaining net book value of retired assets	76			13			(l)
Total regulatory assets (liabilities), net	$	791		$	738

Note: The recovery and amortization periods for these regulatory assets and (liabilities) are as follows:

(a) Asset retirement and removal assets and liabilities are recorded, deferred income tax assets are recovered, and deferred income tax liabilities are amortized over the related property lives, which may range up to 50 years. Asset retirement and removal assets and liabilities will be settled and trued up following completion of the related activities.

(b) Recovered over the remaining life of the original issue, which may range up to 50 years.

(c) Recorded as earned by employees and recovered as paid, generally within one year. This includes both vacation and banked holiday pay.

(d) Recorded and recovered or amortized as approved or accepted by the Alabama PSC over periods not exceeding 10 years.

(e) Fuel-hedging assets and liabilities are recorded over the life of the underlying hedged purchase contracts, which generally do not exceed three and a half years. Upon final settlement, actual costs incurred are recovered through the energy cost recovery clause.

(f) Comprised of components including generation site selection/evaluation costs, PPA capacity, and other miscellaneous assets. Recorded as accepted by the Alabama PSC. Capitalized upon initialization of related construction projects, if applicable.

(g) Comprised of components including mine reclamation and remediation liabilities, fuel-hedging gains and nuclear fuel disposal fee. Recorded as accepted by the Alabama PSC. Mine reclamation and remediation liabilities will be settled following completion of the related activities. Nuclear fuel disposal fees are recorded as approved by the Alabama PSC related to potential future fees for nuclear waste disposal. The balance was transferred to Rate ECR in 2015. See Note 3 for additional information.

(h) Utilized as storm restoration and potential reliability-related expenses are incurred, as approved by the Alabama PSC.

(i) Recovered and amortized over the average remaining service period which may range up to 15 years. See Note 2 for additional information.

(j) Not earning a return as offset in rate base by a corresponding asset or liability.

(k) Included in the deferred income tax charges are $17 million for 2015 and $18 million for 2014 for the retiree Medicare drug subsidy, which is recovered and amortized, as approved by the Alabama PSC, over the average remaining service period which may range up to 15 years.

(l) Recorded and amortized as approved by the Alabama PSC for a period up to 11 years.

Property Plant and Equipment

The Company's property, plant, and equipment in service consisted of the following at December 31:

	2015		2014
	(in millions)
Generation	$	12,820	$	11,670
Transmission	3,773		3,579
Distribution	6,432		6,196
General	1,713		1,623
Plant acquisition adjustment	12		12
Total plant in service	$	24,750	$	23,080

Asset Retirement Obligations and Other Costs of Removal

Details of the AROs included in the balance sheets are as follows:

	2015			2014
	(in millions)
Balance at beginning of year	$	829		$	730
Liabilities incurred	402			1
Liabilities settled	(3		)	(3		)
Accretion	53			45
Cash flow revisions	167			56
Balance at end of year	$	1,448		$	829

Accumulated Provisions for Decommissioning

At December 31, the accumulated provisions for decommissioning were as follows:

	2015		2014
	(in millions)
External trust funds	$	734	$	754
Internal reserves	20		21
Total	$	754	$	775

Estimated Cost of Decommissioning

The estimated costs of decommissioning as of December 31, 2015 based on the most current study performed in 2013 for Plant Farley are as follows:

Decommissioning periods:
Beginning year	2037
Completion year	2076
	(in millions)
Site study costs:
Radiated structures	$	1,362
Non-radiated structures	80
Total site study costs	$	1,442

Gulf Power [Member]

Summary of Significant Accounting Policies [Line Items]

Regulatory Assets and Liabilities

Regulatory assets and (liabilities) reflected in the balance sheets at December 31 relate to:

	2015			2014			Note
	(in millions)
PPA charges	$	163		$	185		(j,k)
Retiree benefit plans, net	147			148			(i,j)
Fuel-hedging assets, net	104			73			(g,j)
Deferred income tax charges	59			53			(a)
Environmental remediation	46			48			(h,j)
Regulatory asset, offset to other cost of removal	29			8			(m)
Closure of Plant Scholz ash pond	29			—			(h,j)
Loss on reacquired debt	15			16			(c)
Vacation pay	10			10			(d,j)
Deferred return on transmission upgrades	10			—			(m)
Other regulatory assets, net	7			9			(l)
Deferred income tax charges — Medicare subsidy	2			3			(b)
Under recovered regulatory clause revenues	1			53			(e)
Other cost of removal obligations	(262		)	(243		)	(a)
Property damage reserve	(38		)	(35		)	(f)
Over recovered regulatory clause revenues	(22		)	—			(e)
Deferred income tax credits	(3		)	(4		)	(a)
Asset retirement obligations, net	(1		)	(5		)	(a,j)
Total regulatory assets (liabilities), net	$	296		$	319

Note: The recovery and amortization periods for these regulatory assets and (liabilities) are as follows:

(a) Asset retirement and removal assets and liabilities are recorded, deferred income tax assets are recovered, and deferred income tax liabilities are amortized over the related property lives, which may range up to 65 years. Asset retirement and removal assets and liabilities will be settled and trued up following completion of the related activities.

(b) Recovered and amortized over periods not exceeding 14 years.

(c) Recovered over either the remaining life of the original issue or, if refinanced, over the life of the new issue, which may range up to 40 years.

(d) Recorded as earned by employees and recovered as paid, generally within one year. This includes both vacation and banked holiday pay.

(e) Recorded and recovered or amortized as approved by the Florida PSC, generally within one year.

(f) Recorded and recovered or amortized as approved by the Florida PSC.

(g) Fuel-hedging assets and liabilities are recorded over the life of the underlying hedged purchase contracts, which generally do not exceed five years. Upon final settlement, actual costs incurred are recovered through the fuel cost recovery clause.

(h) Recovered through the environmental cost recovery clause when the remediation or the work is performed.

(i) Recovered and amortized over the average remaining service period which may range up to 14 years. See Note 2 for additional information.

(j) Not earning a return as offset in rate base by a corresponding asset or liability.

(k) Recovered over the life of the PPA for periods up to eight years.

(l) Comprised primarily of net book value of retired meters and recovery of injuries and damages costs. These costs are recorded and recovered or amortized as approved by the Florida PSC, generally over periods not exceeding eight years.

(m) Recorded as authorized by the Florida PSC in the settlement agreement approved in December 2013 (2013 Rate Case Settlement Agreement). See Note 3 for additional information.

Property Plant and Equipment

The Company's property, plant, and equipment in service consisted of the following at December 31:

	2015		2014
	(in millions)
Generation	$	2,974	$	2,638
Transmission	691		516
Distribution	1,196		1,157
General	182		182
Plant acquisition adjustment	2		2
Total plant in service	$	5,045	$	4,495

Asset Retirement Obligations and Other Costs of Removal

Details of the AROs included in the balance sheets are as follows:

	2015			2014
	(in millions)
Balance at beginning of year	$	17		$	16
Liabilities incurred	105			—
Liabilities settled	(1		)	—
Accretion	2			1
Cash flow revisions	7			—
Balance at end of year	$	130		$	17

Georgia Power [Member]

Summary of Significant Accounting Policies [Line Items]

Regulatory Assets and Liabilities

Regulatory assets and (liabilities) reflected in the balance sheets at December 31 relate to:

	2015			2014			Note
	(in millions)
Retiree benefit plans	$	1,307		$	1,325		(a, j)
Deferred income tax charges	653			668			(b, j)
Loss on reacquired debt	150			163			(c, j)
Asset retirement obligations	411			108			(b, j)
Vacation pay	91			91			(d, j)
Cancelled construction projects	56			67			(e)
Remaining net book value of retired assets	171			29			(f)
Storm damage reserves	92			98			(g)
Other regulatory assets	140			153			(h)
Other cost of removal obligations	(31		)	(60		)	(b)
Deferred income tax credits	(105		)	(106		)	(b, j)
Other regulatory liabilities	(2		)	(7		)	(i, j)
Total regulatory assets (liabilities), net	$	2,933		$	2,529

Note: The recovery and amortization periods for these regulatory assets and (liabilities) are as follows:

(a) Recovered and amortized over the average remaining service period which may range up to 14 years. See Note 2 for additional information.

(b) Asset retirement and other cost of removal obligations and deferred income tax assets are recovered, and deferred income tax liabilities are amortized over the related property lives, which may range up to 70 years. Asset retirement and removal liabilities will be settled and trued up following completion of the related activities. At December 31, 2015, other cost of removal obligations included $14 million that will be amortized over the twelve months ending December 31, 2016 in accordance with the three-year amortization period approved in the Company's 2013 ARP.

(c) Recovered over either the remaining life of the original issue or, if refinanced, over the remaining life of the new issue, which currently does not exceed 38 years.

(d) Recorded as earned by employees and recovered as paid, generally within one year. This includes both vacation and banked holiday pay.

(e) Costs associated with construction of environmental controls that will not be completed as a result of unit retirements are being amortized as approved by the Georgia PSC over periods not exceeding nine years or through 2022.

(f) Amortized as approved by the Georgia PSC over periods not exceeding 10 years or through 2024. Amortization of obsolete inventories will be determined by the Georgia PSC in the 2016 base rate case.

(g) Recorded and recovered or amortized as approved by the Georgia PSC over periods generally not exceeding six years or through 2019.

(h) Comprised of several components including deferred nuclear outages, environmental remediation, Medicare subsidy deferred income tax charges, fuel hedging losses, building lease, and other miscellaneous assets. These costs are recorded and recovered or amortized as approved by the Georgia PSC over periods generally not exceeding 12 years or through 2022.

(i) Comprised primarily of fuel-hedging gains, which upon final settlement are refunded through the Company's fuel cost recovery mechanism.

(j) Generally not earning a return as they are excluded from rate base or are offset in rate base by a corresponding asset or liability.

Property Plant and Equipment

The Company's property, plant, and equipment in service consisted of the following at December 31:

	2015		2014
	(in millions)
Generation	$	15,386	$	15,201
Transmission	5,355		5,086
Distribution	9,151		8,913
General	1,921		1,855
Plant acquisition adjustment	28		28
Total plant in service	$	31,841	$	31,083

Asset Retirement Obligations and Other Costs of Removal

Details of the AROs included in the balance sheets are as follows:

	2015			2014
	(in millions)
Balance at beginning of year	$	1,255		$	1,222
Liabilities incurred	6			9
Liabilities settled	(30		)	(12		)
Accretion	56			53
Cash flow revisions	629			(17		)
Balance at end of year	$	1,916		$	1,255

Accumulated Provisions for Decommissioning

The site study costs and external trust funds for decommissioning as of December 31, 2015 based on the Company's ownership interests were as follows:

	Plant Hatch		Plant Vogtle Units 1 and 2
Decommissioning periods:
Beginning year	2034		2047
Completion year	2075		2079
	(in millions)
Site study costs:
Radiated structures	$	678	$	568
Spent fuel management	160		147
Non-radiated structures	64		89
Total site study costs	$	902	$	804
External trust funds	$	487	$	288

Mississippi Power [Member]

Summary of Significant Accounting Policies [Line Items]

Regulatory Assets and Liabilities

Regulatory assets and (liabilities) reflected in the balance sheets at December 31 relate to:

	2015			2014			Note
	(in millions)
Retiree benefit plans – regulatory assets	$	163		$	169		(a,g)
Property damage	(64		)	(62		)	(i)
Deferred income tax charges	291			227			(c)
Remaining net book value of retired assets	36			2			(b)
Property tax	27			28			(d)
Vacation pay	11			11			(e,g)
Plant Daniel Units 3 and 4 regulatory assets	29			23			(j)
Other regulatory assets	16			18			(b)
Fuel-hedging (realized and unrealized) losses	50			47			(f,g)
Asset retirement obligations	70			11			(c)
Other cost of removal obligations	(167		)	(166		)	(c)
Kemper IGCC regulatory assets	216			148			(h)
Mirror CWIP	—			(271		)	(h)
Other regulatory liabilities	(11		)	(13		)	(b)
Total regulatory assets (liabilities), net	$	667		$	172

Note: The recovery and amortization periods for these regulatory assets and (liabilities) are as follows:

(a) Recovered and amortized over the average remaining service period which may range up to 14 years. See Note 2 for additional information.

(b) Recorded and recovered or amortized as approved by the Mississippi PSC.

(c) Asset retirement and removal assets and liabilities and deferred income tax assets are recovered, and removal assets and deferred income tax liabilities are amortized over the related property lives, which may range up to 49 years. Asset retirement and removal assets and liabilities will be settled and trued up following completion of the related activities.

(d) Recovered through the ad valorem tax adjustment clause over a 12-month period beginning in April of the following year. See Note 3 under "Ad Valorem Tax Adjustment" for additional information.

(e) Recorded as earned by employees and recovered as paid, generally within one year. This includes both vacation and banked holiday pay.

(f) Fuel-hedging assets and liabilities are recorded over the life of the underlying hedged purchase contracts, which generally do not exceed three years. Upon final settlement, actual costs incurred are recovered through the ECM.

(g) Not earning a return as offset in rate base by a corresponding asset or liability.

(h) For additional information, see Note 3 under "Integrated Coal Gasification Combined Cycle – Rate Recovery of Kemper IGCC Costs – Regulatory Assets and Liabilities."

(i) For additional information, see Note 1 under "Provision for Property Damage."

(j) Deferred and amortized over a 10-year period beginning October 2021, as approved by the Mississippi PSC for the difference between the revenue requirement under the purchase option and the revenue requirement assuming operating lease accounting treatment for the extended term.

Property Plant and Equipment

The Company's property, plant, and equipment in service consisted of the following at December 31:

	2015		2014
	(in millions)
Generation	$	2,723	$	2,293
Transmission	688		665
Distribution	891		854
General	503		485
Plant acquisition adjustment	81		81
Total plant in service	$	4,886	$	4,378

Asset Retirement Obligations and Other Costs of Removal

Details of the AROs included in the balance sheets are as follows:

	2015			2014
	(in millions)
Balance at beginning of year	$	48		$	42
Liabilities incurred	101			—
Liabilities settled	(3		)	(3		)
Accretion	4			2
Cash flow revisions	27			7
Balance at end of year	$	177		$	48

Southern Power [Member]

Summary of Significant Accounting Policies [Line Items]

Schedule of Revenue by Major Customers by Reporting Segments

The following table shows the percentage of total revenues for the top three customers:

	2015		2014		2013
Georgia Power	15.8	%	10.1	%	11.8	%
FPL	10.7	%	9.7	%	10.7	%
Duke Energy Corporation	8.2	%	9.1	%	10.3	%

Asset Retirement Obligations and Other Costs of Removal

Details of the AROs included in the balance sheets are as follows:

	2015		2014
	(in millions)
Balance at beginning of year	$	13	$	4
Liabilities incurred	7		8
Accretion	1		1
Balance at end of year	$	21	$	13

Future Amortization Expense for PPAs

The amortization expense for the acquired PPAs for each of the years ended December 31, 2015, 2014, and 2013 was $3 million, and is recorded in operating revenues. The amortization expense for future periods is as follows:

	Amortization Expense
	(in millions)
2016	$	10
2017	17
2018	17
2019	17
2020	17
2021 and beyond	239
Total	$	317