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Organization and Basis of Presentation (Details Textuals) mi in Thousands, MW in Thousands, customer in Millions, $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2016 USD ($) transmission_center | Jun. 30, 2015 USD ($) | Jun. 30, 2016 USD ($) customer transmission_center company mi MW | Jun. 30, 2015 USD ($) | Dec. 31, 2015 USD ($)
Property, Plant and Equipment [Line Items] |  |  |  |  |
Aggregate amount of capacity | MW |  |  | 17 |  |
Length of transmission lines | mi |  |  | 24 |  |
Number of regional transmission centers | transmission_center | 2 |  | 2 |  |
Capitalized cost of equity | $ 9 | $ 14 | $ 17 | $ 30 |
Capitalized interest | 17 | 19 | 34 | 37 |
Impairment of assets | 1,447 | 16 | $ 1,447 | 16 |
New Accounting Pronouncement, Early Adoption, Effect | Deferred Charges and Other Assets |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Debt issuance costs |  |  |  |  | $ 93
Regulated Distribution |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Number of existing utility operating companies | company |  |  | 10 |  |
Number of customers served by utility operating companies | customer |  |  | 6 |  |
Impairment of assets | 0 | 0 | $ 0 | 0 |
FES |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Impairment of assets | $ 540 | $ 16 | $ 540 | $ 16 |
FES | New Accounting Pronouncement, Early Adoption, Effect | Deferred Charges and Other Assets |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Debt issuance costs |  |  |  |  | $ 17

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