Early Termination Fee

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Early Termination Reimbursable Expenses

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- Definition

Energy from Wind-Powered Generating facilities.

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Estimated Cost

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The contracted life output of the plant.

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Percentage Of Entitled Cash Distributions

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Power of solar polycrystalline silicon facility.

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Purchased Power Agreement Intangible

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Reimbursable Transmission Costs Receivable

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Total Cost Of Construction

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

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No definition available.

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This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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In a business combination in which the amount of net identifiable assets acquired and liabilities assumed exceeds the aggregate consideration transferred or to be transferred (as defined), this element represents the amount of gain recognized by the entity.

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Amount of equity interests of the acquirer, including instruments or interests issued or issuable in consideration for the business combination.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of deferred tax liability attributable to taxable temporary differences due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

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The amount of property, plant, and equipment recognized as of the acquisition date.

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For transactions that are recognized separately from the acquisition of assets and assumptions of liabilities in the business combination, such as related to pre-existing relationships with the acquiree, this element represents the disclosure of the amount of acquisition related costs which have been expensed.

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- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

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Carrying value as of the balance sheet date of obligations incurred and payable for the acquisition of merchandise, materials, supplies and services pertaining to construction projects such as a housing development or factory expansion not classified as trade payables.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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No definition available.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Acquisitions - Textual (Details)									3 Months Ended								9 Months Ended	12 Months Ended
Acquisitions - Textual (Details)	Feb. 24, 2016 USD ($) $ / shares	Dec. 11, 2015 USD ($) MW	Aug. 23, 2015 USD ($) $ / shares	Feb. 24, 2015 USD ($)	Nov. 26, 2014 USD ($)	Nov. 06, 2014 USD ($) MW	May. 22, 2014 USD ($) MW	Apr. 17, 2014 USD ($) MW	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($) MW	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2015 USD ($) MW	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Feb. 11, 2016	Oct. 22, 2015	Aug. 31, 2015 USD ($)	Apr. 15, 2015
Business Acquisition [Line Items]
Construction in Progress, Gross									$ 9,082,000,000				$ 7,792,000,000					$ 9,082,000,000	$ 7,792,000,000
Line of Credit Facility, Maximum Borrowing Capacity									6,505,000,000									6,505,000,000
Revenues									3,568,000,000	$ 5,401,000,000	$ 4,337,000,000	$ 4,183,000,000	4,017,000,000	$ 5,339,000,000	$ 4,467,000,000	$ 4,644,000,000		17,489,000,000	18,467,000,000	$ 17,087,000,000
Southern Power [Member]
Business Acquisition [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed																		4,000,000
Construction in Progress, Gross									1,137,000,000				11,000,000					1,137,000,000	11,000,000
Power of Solar Polycrystalline Silicon Facility \| MW										146							146
Life Output Of Plant																	25 years
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months									10,000,000									10,000,000
Line of Credit Facility, Maximum Borrowing Capacity									600,000,000				500,000,000					600,000,000	500,000,000				$ 600,000,000
Total Cost Of Construction																		1,800,000,000
Revenues									304,000,000	$ 401,000,000	$ 337,000,000	$ 348,000,000	$ 386,000,000	$ 435,000,000	$ 329,000,000	$ 351,000,000		1,390,000,000	$ 1,501,000,000	$ 1,275,000,000
Southern Power [Member] \| Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Revenues																		18,000,000
Southern Power [Member] \| Adobe Solar LLC [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent								90.00%
Power of Solar Polycrystalline Silicon Facility \| MW								20
Life Output Of Plant								20 years
Payments to Acquire Businesses, Gross							$ 97,000,000	$ 86,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment								84,000,000
Reimbursable Transmission Costs Receivable								15,000,000
Purchased Power Agreement Intangible								6,000,000
Business Combination, Bargain Purchase, Gain Recognized, Amount								5,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent								$ 3,000,000
Southern Power [Member] \| Macho Springs, LLC [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent							90.00%
Power of Solar Polycrystalline Silicon Facility \| MW							50
Life Output Of Plant							20 years
Payments to Acquire Businesses, Gross							$ 117,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment							128,000,000
Reimbursable Transmission Costs Receivable							1,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets							$ 1,000,000
Southern Power [Member] \| Solar Gen 2 Imperial Valley, LLC [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent						51.00%
Power of Solar Polycrystalline Silicon Facility \| MW						150
Life Output Of Plant						25 years
Payments to Acquire Businesses, Gross						$ 505,000,000			505,000,000
Southern Power [Member] \| First Solar [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross						$ 128,000,000			599,000,000
Southern Power [Member] \| Decatur Parkway Solar Project, LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility \| MW										84							84
Life Output Of Plant																	25 years
Estimated Cost																	$ 169,000,000
Southern Power [Member] \| Decatur County Solar Project, LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility \| MW										20							20
Life Output Of Plant																	20 years
Estimated Cost																	$ 46,000,000
Southern Power [Member] \| Kay Wind, LLC [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		100.00%
Construction in Progress, Gross									481,000,000									481,000,000
Construction Payable									8,000,000									8,000,000
Life Output Of Plant		20 years
Payments to Acquire Businesses, Gross		$ 481,000,000		$ 481,000,000
Reimbursable Transmission Costs Receivable									8,000,000									8,000,000
Energy From Wind-Powered Generating Facilities \| MW		299
First Solar [Member] \| Solar Gen 2 Imperial Valley, LLC [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross									223,000,000
SG2 Holdings, LLC [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross					$ 593,000,000				6,000,000
SG2 Holdings, LLC [Member] \| Solar Gen 2 Imperial Valley, LLC [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment									708,000,000									708,000,000
Reimbursable Transmission Costs Receivable									$ 20,000,000									$ 20,000,000
Class A Membership Interest [Member] \| Southern Power [Member] \| Solar Gen 2 Imperial Valley, LLC [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent									100.00%									100.00%
Percentage Of Entitled Cash Distributions																								51.00%
Class B Membership Interest [Member] \| First Solar [Member] \| Solar Gen 2 Imperial Valley, LLC [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent									100.00%									100.00%
Percentage Of Entitled Cash Distributions																								49.00%
Turner Renewable Energy [Member] \| Southern Power [Member]
Business Acquisition [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share									10.00%									10.00%				10.00%
Minimum [Member] \| Southern Power [Member]
Business Acquisition [Line Items]
Estimated Cost																	260,000,000
Maximum [Member] \| Southern Power [Member]
Business Acquisition [Line Items]
Estimated Cost																	$ 280,000,000
Bridge Agreement [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs																		$ 41,000,000
Scenario, Plan [Member] \| Bridge Agreement [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price \| $ / shares			$ 66
Payments to Acquire Businesses, Gross			$ 8,200,000,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable			8,000,000,000
Business Combination, Acquisition Related Costs			$ 200,000,000
Line of Credit Facility, Maximum Borrowing Capacity									$ 8,100,000,000.0									8,100,000,000.0
Scenario, Plan [Member] \| Bridge Agreement [Member] \| AGL Resources [Member]
Business Acquisition [Line Items]
Early Termination Fee									201,000,000									201,000,000
Early Termination Reimbursable Expenses									$ 5,000,000									$ 5,000,000
Subsequent Event [Member] \| Turner Renewable Energy [Member] \| Southern Power [Member]
Business Acquisition [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share																					10.00%
Subsequent Event [Member] \| Scenario, Plan [Member] \| PowerSecure International, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price \| $ / shares	$ 18.75
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	$ 431,000,000