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Transactions With Affiliated Companies (Details) T in Millions, $ in Millions | 12 Months Ended
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Dec. 31, 2017 USD ($) T | Dec. 31, 2016 USD ($) T | Dec. 31, 2015 USD ($) T
MP | FES |  |  |
REVENUES: |  |  |
Revenues |  | $ 31 |
Interest Expense: |  |  |
Amount of coal sold under purchase agreement (in T) | T |  | 0.7 |
AE Supply and MP | FES |  |  |
REVENUES: |  |  |
Revenues |  |  | $ 0
AE Supply | FES |  |  |
REVENUES: |  |  |
Revenues | $ 41 | $ 16 |
Interest Expense: |  |  |
Amount of coal sold under purchase agreement (in T) | T | 1.1 | 0.4 |
FES |  |  |
Investment Income: |  |  |
Interest income from FE | $ 13 | $ 2 | 2
Interest Expense: |  |  |
Interest expense to affiliates | 0 | 5 | 4
Interest expense to FE | 19 | 2 | 3
FES | AE Supply |  |  |
REVENUES: |  |  |
Revenues | $ 15 | $ 80 | $ 63
Interest Expense: |  |  |
Amount of coal sold under purchase agreement (in T) | T | 0.4 | 1.5 | 1.2
FES | Electric sales to affiliates |  |  |
REVENUES: |  |  |
Revenues | $ 366 | $ 459 | $ 666
FES | Other |  |  |
REVENUES: |  |  |
Revenues | 11 | 11 | 14
FES | Purchased power from affiliates |  |  |
Expenses: |  |  |
Expenses | 201 | 622 | 353
FES | Fuel |  |  |
Expenses: |  |  |
Expenses | 4 | 4 | 1
FES | Support services |  |  |
Expenses: |  |  |
Expenses | $ 775 | $ 748 | $ 705

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