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Fair Value Measurements
12 Months Ended
Dec. 31, 2015
Fair Value Disclosures [Line Items]  
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS
Fair value measurements are based on inputs of observable and unobservable market data that a market participant would use in pricing the asset or liability. The use of observable inputs is maximized where available and the use of unobservable inputs is minimized for fair value measurement and reflects a three-tier fair value hierarchy that prioritizes inputs to valuation techniques used for fair value measurement.
Level 1 consists of observable market data in an active market for identical assets or liabilities.
Level 2 consists of observable market data, other than that included in Level 1, that is either directly or indirectly observable.
Level 3 consists of unobservable market data. The input may reflect the assumptions of the Company of what a market participant would use in pricing an asset or liability. If there is little available market data, then the Company's own assumptions are the best available information.
In the case of multiple inputs being used in a fair value measurement, the lowest level input that is significant to the fair value measurement represents the level in the fair value hierarchy in which the fair value measurement is reported.
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.
As of December 31, 2014, 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, 2014:
(Level 1)
 
(Level 2)
 
(Level 3)
 
(NAV)
 
Total
 
(in millions)
Assets:
 
 
 
 
 
 
 
 
 
Energy-related derivatives
$

 
$
13

 
$

 
$

 
$
13

Interest rate derivatives

 
8

 

 

 
8

Nuclear decommissioning trusts:(*)
 
 
 
 
 
 
 
 
 
Domestic equity
583

 
85

 

 

 
668

Foreign equity
34

 
184

 

 

 
218

U.S. Treasury and government agency securities

 
130

 

 

 
130

Municipal bonds

 
62

 

 

 
62

Corporate bonds

 
299

 

 

 
299

Mortgage and asset backed securities

 
139

 

 

 
139

Private equity

 

 

 
3

 
3

Other
11

 
13

 

 

 
24

Cash equivalents
397

 

 

 

 
397

Other investments
9

 

 
1

 

 
10

Total
$
1,034

 
$
933

 
$
1

 
$
3

 
$
1,971

Liabilities:
 
 
 
 
 
 
 
 
 
Energy-related derivatives
$

 
$
201

 
$

 
$

 
$
201

Interest rate derivatives

 
24

 

 

 
24

Total
$

 
$
225

 
$

 
$

 
$
225

(*)
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.
Valuation Methodologies
The energy-related derivatives primarily consist of over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflect the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk and occasionally, implied volatility of interest rate options. The interest rate derivatives are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note 11 for additional information on how these derivatives are used.
The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. For fair value measurements of the investments within the nuclear decommissioning trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available. See Note 1 under "Nuclear Decommissioning" for additional information.
"Other investments" include investments that are not traded in the open market. The fair value of these investments have been determined based on market factors including comparable multiples and the expectations regarding cash flows and business plan executions.
Southern Company early adopted ASU 2015-07 effective December 31, 2015. As required, disclosures in the paragraphs and tables below are limited to only those investments in funds that are measured at net asset value as a practical expedient. In accordance with ASU 2015-07, previously reported amounts have been conformed to the current presentation.
As of December 31, 2015 and 2014, 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, 2015
$
17


$
28


Not Applicable

Not Applicable
As of December 31, 2014
$
3

 
$
7

 
Not Applicable
 
Not Applicable

Private equity funds include a fund-of-funds that invests in high quality private equity funds across several market sectors, a fund that invests in real estate assets, and a fund that acquires companies to create resale value. Private equity funds do not have redemption rights. Distributions from these funds will be received as the underlying investments in the funds are liquidated. Liquidations are expected to occur at various times over the next ten years.
As of December 31, 2015 and 2014, 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:
 
 
 
2015
$
27,216

 
$
27,913

2014
$
23,814

 
$
25,816


The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on the current rates available to Southern Company, Alabama Power, Georgia Power, Gulf Power, Mississippi Power, and Southern Power.
Alabama Power [Member]  
Fair Value Disclosures [Line Items]  
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS
Fair value measurements are based on inputs of observable and unobservable market data that a market participant would use in pricing the asset or liability. The use of observable inputs is maximized where available and the use of unobservable inputs is minimized for fair value measurement and reflects a three-tier fair value hierarchy that prioritizes inputs to valuation techniques used for fair value measurement.
Level 1 consists of observable market data in an active market for identical assets or liabilities.
Level 2 consists of observable market data, other than that included in Level 1, that is either directly or indirectly observable.
Level 3 consists of unobservable market data. The input may reflect the assumptions of the Company of what a market participant would use in pricing an asset or liability. If there is little available market data, then the Company's own assumptions are the best available information.
In the case of multiple inputs being used in a fair value measurement, the lowest level input that is significant to the fair value measurement represents the level in the fair value hierarchy in which the fair value measurement is reported.
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.
As of December 31, 2014, 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, 2014:
(Level 1)
 
(Level 2)
 
(Level 3)
 
(NAV)
 
Total
 
(in millions)
Assets:
 
 
 
 
 
 
 
 
 
Energy-related derivatives
$

 
$
1

 
$

 
$

 
$
1

Nuclear decommissioning trusts:(*)


 


 


 
 
 


Domestic equity
403

 
83

 

 

 
486

Foreign equity
34

 
63

 

 

 
97

U.S. Treasury and government agency securities

 
34

 

 

 
34

Corporate bonds

 
111

 

 

 
111

Mortgage and asset backed securities

 
18

 

 

 
18

Private equity

 

 

 
3

 
3

Other

 
5

 

 

 
5

Cash equivalents
162

 

 

 

 
162

Total
$
599

 
$
315

 
$

 
$
3

 
$
917

Liabilities:
 
 
 
 
 
 
 
 
 
Interest rate derivatives
$

 
$
8

 
$

 
$

 
$
8

Energy-related derivatives

 
53

 

 

 
53

Total
$

 
$
61

 
$

 
$

 
$
61

(*)
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.
Valuation Methodologies
The energy-related derivatives primarily consist of over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflect the net present value of expected payments and receipts under the swap agreement based on the market’s expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk and occasionally, implied volatility of interest rate options. The interest rate derivatives are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note 11 for additional information on how these derivatives are used.
The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. For fair value measurements of the investments within the nuclear decommissioning trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. See Note 1 under "Nuclear Decommissioning" for additional information.
A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available.
The Company early adopted ASU 2015-07 effective December 31, 2015. As required, disclosures in the paragraphs and table below are limited to only those investments in funds that are measured at net asset value as a practical expedient. In accordance with ASU 2015-07, previously reported amounts have been conformed to the current presentation.
As of December 31, 2015 and 2014, 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, 2015
$
17

 
$
28

 
Not Applicable
 
Not Applicable
As of December 31, 2014
$
3

 
$
7

 
Not
Applicable
 
Not Applicable

Private equity funds include a fund-of-funds that invests in high quality private equity funds across several market sectors, a fund that invests in real estate assets, and a fund that acquires companies to create resale value. Private equity funds do not have redemption rights. Distributions from these funds will be received as the underlying investments in the funds are liquidated. Liquidations of these investments are expected to occur at various times over the next ten years.
As of December 31, 2015 and 2014, 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:
 
 
 
2015
$
6,849

 
$
7,192

2014
$
6,586

 
$
7,321


The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on the current rates available to the Company.
Georgia Power [Member]  
Fair Value Disclosures [Line Items]  
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS
Fair value measurements are based on inputs of observable and unobservable market data that a market participant would use in pricing the asset or liability. The use of observable inputs is maximized where available and the use of unobservable inputs is minimized for fair value measurement and reflects a three-tier fair value hierarchy that prioritizes inputs to valuation techniques used for fair value measurement.
Level 1 consists of observable market data in an active market for identical assets or liabilities.
Level 2 consists of observable market data, other than that included in Level 1, that is either directly or indirectly observable.
Level 3 consists of unobservable market data. The input may reflect the assumptions of the Company of what a market participant would use in pricing an asset or liability. If there is little available market data, then the Company's own assumptions are the best available information.
In the case of multiple inputs being used in a fair value measurement, the lowest level input that is significant to the fair value measurement represents the level in the fair value hierarchy in which the fair value measurement is reported.
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.
As of December 31, 2014, 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, 2014:
(Level 1)
 
(Level 2)
 
(Level 3)
 
Total
 
(in millions)
Assets:
 
 
 
 
 
 
 
Energy-related derivatives
$

 
$
7

 
$

 
$
7

Interest rate derivatives

 
6

 

 
6

Nuclear decommissioning trusts:(*)
 
 
 
 
 
 
 
Domestic equity
180

 
2

 

 
182

Foreign equity

 
121



 
121

U.S. Treasury and government agency securities

 
96

 

 
96

Municipal bonds

 
62

 

 
62

Corporate bonds

 
188

 

 
188

Mortgage and asset backed securities

 
121

 

 
121

Other
11

 
8

 

 
19

Total
$
191

 
$
611

 
$

 
$
802

Liabilities:
 
 
 
 
 
 
 
Energy-related derivatives
$

 
$
27

 
$

 
$
27

Interest rate derivatives

 
14

 

 
14

Total
$

 
$
41

 
$

 
$
41

(*)
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.
Valuation Methodologies
The energy-related derivatives primarily consist of over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflect the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk and occasionally, implied volatility of interest rate options. The interest rate derivatives are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note 11 for additional information on how these derivatives are used.
The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. For fair value measurements of the investments within the nuclear decommissioning trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available. See Note 1 under "Nuclear Decommissioning" for additional information.
The Company early adopted ASU 2015-07 effective December 31, 2015 on a retrospective basis. The guidance removed certain disclosures required for all investments that are eligible to be measured at fair value using the net asset value per share practical expedient regardless of whether the practical expedient was used. As of December 31, 2015 and 2014, the Company had no investments measured at net asset value as a practical expedient.
As of December 31, 2015 and 2014, 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:
 
 
 
2015
$
10,145

 
$
10,480

2014
$
9,673

 
$
10,552


The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on current rates available to the Company.
Gulf Power [Member]  
Fair Value Disclosures [Line Items]  
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS
Fair value measurements are based on inputs of observable and unobservable market data that a market participant would use in pricing the asset or liability. The use of observable inputs is maximized where available and the use of unobservable inputs is minimized for fair value measurement and reflects a three-tier fair value hierarchy that prioritizes inputs to valuation techniques used for fair value measurement.
Level 1 consists of observable market data in an active market for identical assets or liabilities.
Level 2 consists of observable market data, other than that included in Level 1, that is either directly or indirectly observable.
Level 3 consists of unobservable market data. The input may reflect the assumptions of the Company of what a market participant would use in pricing an asset or liability. If there is little available market data, then the Company's own assumptions are the best available information.
In the case of multiple inputs being used in a fair value measurement, the lowest level input that is significant to the fair value measurement represents the level in the fair value hierarchy in which the fair value measurement is reported.
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

As of December 31, 2014, 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, 2014:
(Level 1)
 
(Level 2)
 
(Level 3)
 
Total
 
(in millions)
Assets:
 
 
 
 
 
 
 
Cash equivalents
$
18

 
$

 
$

 
$
18

Liabilities:
 
 
 
 
 
 
 
Energy-related derivatives
$

 
$
72

 
$

 
$
72


Valuation Methodologies
The energy-related derivatives primarily consist of over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflect the net present value of expected payments and receipts under the swap agreement based on the market’s expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk and occasionally, implied volatility of interest rate options. The interest rate derivatives are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note 10 for additional information on how these derivatives are used.
As of December 31, 2015 and 2014, 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:
 
 
 
2015
$
1,303

 
$
1,339

2014
$
1,362

 
$
1,477


The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on the current rates available to the Company.
Mississippi Power [Member]  
Fair Value Disclosures [Line Items]  
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS
Fair value measurements are based on inputs of observable and unobservable market data that a market participant would use in pricing the asset or liability. The use of observable inputs is maximized where available and the use of unobservable inputs is minimized for fair value measurement and reflects a three-tier fair value hierarchy that prioritizes inputs to valuation techniques used for fair value measurement.
Level 1 consists of observable market data in an active market for identical assets or liabilities.
Level 2 consists of observable market data, other than that included in Level 1, that is either directly or indirectly observable.
Level 3 consists of unobservable market data. The input may reflect the assumptions of the Company of what a market participant would use in pricing an asset or liability. If there is little available market data, then the Company's own assumptions are the best available information.
In the case of multiple inputs being used in a fair value measurement, the lowest level input that is significant to the fair value measurement represents the level in the fair value hierarchy in which the fair value measurement is reported.
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

As of December 31, 2014, 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, 2014:
(Level 1)
 
(Level 2)
 
(Level 3)
 
Total
 
(in millions)
Assets:
 
 
 
 
 
 
 
Cash equivalents
$
115

 
$

 
$

 
$
115

Liabilities:
 
 
 
 
 
 
 
Energy-related derivatives
$

 
$
45

 
$

 
$
45


Valuation Methodologies
The energy-related derivatives primarily consist of over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Foreign currency derivatives are also standard over-the-counter financial products valued using the market approach. Inputs for foreign currency derivatives are from observable market sources. See Note 10 for additional information on how these derivatives are used.
As of December 31, 2015 and 2014, 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:
 
 
 
2015
$
2,537

 
$
2,413

2014
$
2,320

 
$
2,382


The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on the current rates offered to the Company.
Southern Power [Member]  
Fair Value Disclosures [Line Items]  
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS
Fair value measurements are based on inputs of observable and unobservable market data that a market participant would use in pricing the asset or liability. The use of observable inputs is maximized where available and the use of unobservable inputs is minimized for fair value measurement and reflects a three-tier fair value hierarchy that prioritizes inputs to valuation techniques used for fair value measurement.
Level 1 consists of observable market data in an active market for identical assets or liabilities.
Level 2 consists of observable market data, other than that included in Level 1, that is either directly or indirectly observable.
Level 3 consists of unobservable market data. The input may reflect the assumptions of the Company of what a market participant would use in pricing an asset or liability. If there is little available market data, then the Company's own assumptions are the best available information.
In the case of multiple inputs being used in a fair value measurement, the lowest level input that is significant to the fair value measurement represents the level in the fair value hierarchy in which the fair value measurement is reported.
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

As of December 31, 2014, 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, 2014:
(Level 1)
 
(Level 2)
 
(Level 3)
 
Total
 
(in millions)
Assets:
 
 
 
 
 
 
 
Energy-related derivatives
$

 
$
5

 
$

 
$
5

Cash equivalents
18

 

 

 
18

Total
$
18

 
$
5

 
$

 
$
23

Liabilities:
 
 
 
 
 
 
 
Energy-related derivatives
$

 
$
4

 
$

 
$
4


Valuation Methodologies
The energy-related derivatives primarily consist of over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflect the net present value of expected payments and receipts under the swap agreement based on the market’s expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk and occasionally, implied volatility of interest rate options. The interest rate derivatives are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note 9 for additional information on how these derivatives are used.
As of December 31, 2015 and 2014, 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:
 
 
 
2015
$
3,122

 
$
3,117

2014
$
1,610

 
$
1,785


The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on the current rates available to the Company.