Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

Assets and liabilities measured at fair value on a recurring basis

As of December 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
As of December 31, 2016:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Assets:
Energy-related derivatives^(a)(b)	$	338	$	333	$	—	$	—	$	671
Interest rate derivatives	—		14		—		—		14
Nuclear decommissioning trusts:^(c)
Domestic equity	589		73		—		—		662
Foreign equity	48		168		—		—		216
U.S. Treasury and government agency securities	—		92		—		—		92
Municipal bonds	—		73		—		—		73
Corporate bonds	22		310		—		—		332
Mortgage and asset backed securities	—		183		—		—		183
Private equity	—		—		—		20		20
Other	11		15		—		—		26
Cash equivalents	1,172		—		—		—		1,172
Other investments	9		—		1		—		10
Total	$	2,189	$	1,261	$	1	$	20	$	3,471
Liabilities:
Energy-related derivatives^(a)(b)	$	345	$	285	$	—	$	—	$	630
Interest rate derivatives	—		29		—		—		29
Foreign currency derivatives	—		58		—		—		58
Contingent consideration	—		—		18		—		18
Total	$	345	$	372	$	18	$	—	$	735


(a)	Energy-related derivatives exclude $4 million associated with certain weather derivatives accounted for based on intrinsic value rather than fair value.


(b)	Energy-related derivatives exclude cash collateral of $62 million.


(c)	Includes the investment securities pledged to creditors and collateral received, and excludes receivables related to investment income, pending investment sales, and payables related to pending investment purchases and the lending pool. See Note 1 under "Nuclear Decommissioning" for additional information.

As of December 31, 2015, 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
As of December 31, 2015:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Assets:
Energy-related derivatives	$	—	$	7	$	—	$	—	$	7
Interest rate derivatives	—		22		—		—		22
Nuclear decommissioning trusts:^(*)
Domestic equity	541		69		—		—		610
Foreign equity	47		160		—		—		207
U.S. Treasury and government agency securities	—		152		—		—		152
Municipal bonds	—		64		—		—		64
Corporate bonds	11		278		—		—		289
Mortgage and asset backed securities	—		145		—		—		145
Private equity	—		—		—		17		17
Other	16		9		—		—		25
Cash equivalents	790		—		—		—		790
Other investments	9		—		1		—		10
Total	$	1,414	$	906	$	1	$	17	$	2,338
Liabilities:
Energy-related derivatives	$	—	$	220	$	—	$	—	$	220
Interest rate derivatives	—		30		—		—		30
Total	$	—	$	250	$	—	$	—	$	250


(*)	Includes the investment securities pledged to creditors and collateral received, and excludes receivables related to investment income, pending investment sales, and payables related to pending investment purchases and the lending pool. See Note 1 under "Nuclear Decommissioning" for additional information.

Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments

As of December 31, 2016 and 2015, 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:



	Fair Value		Unfunded Commitments		Redemption Frequency	Redemption Notice Period
	(in millions)
As of December 31, 2016	$	20	$	25	Not Applicable	Not Applicable
As of December 31, 2015	$	17	$	28	Not Applicable	Not Applicable

Financial instruments not having carrying amount equal to fair value

As of December 31, 2016 and 2015, 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:
2016	$	45,080	$	46,286
2015	$	27,216	$	27,913

Alabama Power [Member]

Fair Value Disclosures [Line Items]

Assets and liabilities measured at fair value on a recurring basis

As of December 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
As of December 31, 2016:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Assets:
Energy-related derivatives	$	—	$	20	$	—	$	—	$	20
Nuclear decommissioning trusts:^(*)
Domestic equity	385		72		—		—		457
Foreign equity	48		47		—		—		95
U.S. Treasury and government agency securities	—		21		—		—		21
Corporate bonds	22		146		—		—		168
Mortgage and asset backed securities	—		19		—		—		19
Private equity	—		—		—		20		20
Other	—		10		—		—		10
Cash equivalents	262		—		—		—		262
Total	$	717	$	335	$	—	$	20	$	1,072
Liabilities:
Energy-related derivatives	$	—	$	9	$	—	$	—	$	9


(*)	Excludes receivables related to investment income, pending investment sales, and payables related to pending investment purchases. See Note 1 under "Nuclear Decommissioning" for additional information.

As of December 31, 2015, 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs		Net Asset Value as a Practical Expedient
As of December 31, 2015:	(Level 1)		(Level 2)		(Level 3)		(NAV)		Total
	(in millions)
Assets:
Energy-related derivatives	$	—	$	1	$	—	$	—	$	1
Nuclear decommissioning trusts:^(*)
Domestic equity	359		68		—		—		427
Foreign equity	47		47		—		—		94
U.S. Treasury and government agency securities	—		27		—		—		27
Corporate bonds	11		135		—		—		146
Mortgage and asset backed securities	—		18		—		—		18
Private equity	—		—		—		17		17
Other	—		5		—		—		5
Cash equivalents	68		—		—		—		68
Total	$	485	$	301	$	—	$	17	$	803
Liabilities:
Interest rate derivatives	$	—	$	15	$	—	$	—	$	15
Energy-related derivatives	—		55		—		—		55
Total	$	—	$	70	$	—	$	—	$	70


(*)	Excludes receivables related to investment income, pending investment sales, and payables related to pending investment purchases. See Note 1 under "Nuclear Decommissioning" for additional information.

Fair value measurements of investments calculated at net asset value per share as well as the nature and risk of those investments

As of December 31, 2016 and 2015, the fair value measurements of private equity investments held in the nuclear decommissioning trusts 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:



	Fair Value		Unfunded Commitments		Redemption Frequency	Redemption Notice Period
	(in millions)
As of December 31, 2016	$	20	$	25	Not Applicable	Not Applicable
As of December 31, 2015	$	17	$	28	Not Applicable	Not Applicable

Financial instruments not having carrying amount equal to fair value

As of December 31, 2016 and 2015, 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:
2016	$	7,092	$	7,544
2015	$	6,849	$	7,192

Georgia Power [Member]

Fair Value Disclosures [Line Items]

Assets and liabilities measured at fair value on a recurring basis

As of December 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
As of December 31, 2016:	(Level 1)		(Level 2)		(Level 3)		Total
	(in millions)
Assets:
Energy-related derivatives	$	—	$	44	$	—	$	44
Interest rate derivatives	—		2		—		2
Nuclear decommissioning trusts:^(*)
Domestic equity	204		1		—		205
Foreign equity	—		121		—		121
U.S. Treasury and government agency securities	—		71		—		71
Municipal bonds	—		73		—		73
Corporate bonds	—		164		—		164
Mortgage and asset backed securities	—		164		—		164
Other	11		5		—		16
Total	$	215	$	645	$	—	$	860
Liabilities:
Energy-related derivatives	$	—	$	8	$	—	$	8
Interest rate derivatives	—		3		—		3
Total	$	—	$	11	$	—	$	11


(*)	Includes the investment securities pledged to creditors and collateral received, and excludes receivables related to investment income, pending investment sales, and payables related to pending investment purchases and the lending pool. See Note 1 under "Nuclear Decommissioning" for additional information.

As of December 31, 2015, 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
As of December 31, 2015:	(Level 1)		(Level 2)		(Level 3)		Total
	(in millions)
Assets:
Energy-related derivatives	$	—	$	2	$	—	$	2
Interest rate derivatives	—		5		—		5
Nuclear decommissioning trusts:^(*)
Domestic equity	182		1		—		183
Foreign equity	—		113		—		113
U.S. Treasury and government agency securities	—		125		—		125
Municipal bonds	—		64		—		64
Corporate bonds	—		143		—		143
Mortgage and asset backed securities	—		127		—		127
Other	16		4		—		20
Cash equivalents	63		—		—		63
Total	$	261	$	584	$	—	$	845
Liabilities:
Energy-related derivatives	$	—	$	15	$	—	$	15
Interest rate derivatives	—		6		—		6
Total	$	—	$	21	$	—	$	21


(*)	Includes the investment securities pledged to creditors and collateral received, and excludes receivables related to investment income, pending investment sales, and payables related to pending investment purchases and the lending pool. See Note 1 under "Nuclear Decommissioning" for additional information.

Financial instruments not having carrying amount equal to fair value

As of December 31, 2016 and 2015, 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:
2016	$	10,516	$	11,034
2015	$	10,145	$	10,480

Gulf Power [Member]

Fair Value Disclosures [Line Items]

Assets and liabilities measured at fair value on a recurring basis

As of December 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
As of December 31, 2016:	(Level 1)		(Level 2)		(Level 3)		Total
	(in millions)
Assets:
Cash equivalents	$	20	$	—	$	—	$	20
Energy-related derivatives	—		5		—		5
Total	$	20	$	5	$	—	$	25
Liabilities:
Energy-related derivatives	$	—	$	29	$	—	$	29

As of December 31, 2015, 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
As of December 31, 2015:	(Level 1)		(Level 2)		(Level 3)		Total
	(in millions)
Assets:
Interest rate derivatives	$	—	$	1	$	—	$	1
Cash equivalents	18		—		—		18
Total	$	18	$	1	$	—	$	19
Liabilities:
Energy-related derivatives	$	—	$	100	$	—	$	100

Financial instruments not having carrying amount equal to fair value

As of December 31, 2016 and 2015, 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:
2016	$	1,074	$	1,097
2015	$	1,303	$	1,339

Mississippi Power [Member]

Fair Value Disclosures [Line Items]

Assets and liabilities measured at fair value on a recurring basis

As of December 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
As of December 31, 2016:	(Level 1)		(Level 2)		(Level 3)		Total
	(in millions)
Assets:
Energy-related derivatives	$	—	$	3	$	—	$	3
Interest rate derivatives	—		3		—		3
Cash equivalents	206		—		—		206
Total	$	206	$	6	$	—	$	212
Liabilities:
Energy-related derivatives	$	—	$	10	$	—	$	10

As of December 31, 2015, 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
As of December 31, 2015:	(Level 1)		(Level 2)		(Level 3)		Total
	(in millions)
Assets:
Cash equivalents	$	52	$	—	$	—	$	52
Liabilities:
Energy-related derivatives	$	—	$	47	$	—	$	47

Financial instruments not having carrying amount equal to fair value

As of December 31, 2016 and 2015, 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:
2016	$	2,979	$	2,922
2015	$	2,537	$	2,413

Southern Power [Member]

Fair Value Disclosures [Line Items]

Assets and liabilities measured at fair value on a recurring basis

As of December 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
As of December 31, 2016:	(Level 1)		(Level 2)		(Level 3)		Total
	(in millions)
Assets:
Energy-related derivatives	$	—	$	21	$	—	$	21
Interest rate derivatives	—		1		—		1
Cash equivalents	628		—		—		628
Total	$	628	$	22	$	—	$	650
Liabilities:
Energy-related derivatives	$	—	$	5	$	—	$	5
Foreign currency derivatives	—		58		—		58
Contingent consideration	—		—		18		18
Total	$	—	$	63	$	18	$	81

As of December 31, 2015, 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
	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
As of December 31, 2015:	(Level 1)		(Level 2)		(Level 3)		Total
	(in millions)
Assets:
Energy-related derivatives	$	—	$	4	$	—	$	4
Interest rate derivatives	—		3		—		3
Cash equivalents	511		—		—		511
Total	$	511	$	7	$	—	$	518
Liabilities:
Energy-related derivatives	$	—	$	3	$	—	$	3

Financial instruments not having carrying amount equal to fair value

As of December 31, 2016 and 2015, 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:
2016	$	5,628	$	5,691
2015	$	3,122	$	3,117

Southern Company Gas [Member]

Fair Value Disclosures [Line Items]

Assets and liabilities measured at fair value on a recurring basis

As of December 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^(a)(b)
Successor – As of December 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)
Assets:
Energy-related derivatives	$	338	$	239	$	—	$	—	$	577
Liabilities:
Energy-related derivatives	$	345	$	224	$	—	$	—	$	569


(a)	Energy-related derivatives excludes $4 million associated with certain weather derivatives accounted for based on intrinsic value rather than fair value.


(b)	Energy-related derivatives excludes cash collateral of $62 million.

As of December 31, 2015, 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^(a)(b)
Predecessor – As of December 31, 2015	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)
Assets:
Energy-related derivatives	$	53	$	113	$	—	$	—	$	166
Interest rate derivatives	—		9		—		—		9
Total	$	53	$	122	$	—	$	—	$	175
Liabilities:
Energy-related derivatives	$	63	$	46	$	—	$	—	$	109


(a)	Energy-related derivatives excludes $10 million associated with certain weather derivatives accounted for based on intrinsic value rather than fair value.


(b)	Energy-related derivatives excludes cash collateral of $96 million.

Financial instruments not having carrying amount equal to fair value

The following table presents the carrying amount and fair value of the Company's long-term debt as of December 31:



	Carrying Amount		Fair Value
	(in millions)
Long-term debt, including securities due within one year:
Successor – As of December 31, 2016	$	5,281	$	5,491
Predecessor – As of December 31, 2015	$	3,820	$	4,066