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Asset Retirement Obligations (Tables) | 12 Months Ended
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Dec. 31, 2016
Asset Retirement Obligation [Abstract] |
Fair values of the decommissioning trust assets | The fair values of the decommissioning trust assets as of December 31, 2016 and 2015 were as follows:
|  | 2016 |  | 2015
|  | (In millions)
FirstEnergy |  | $ | 2,514 |  |  | $ | 2,282 |
FES |  | $ | 1,552 |  |  | $ | 1,327 |
Changes to the asset retirement obligations | The following table summarizes the changes to the ARO balances during 2016 and 2015:
ARO Reconciliation |  | FirstEnergy |  | FES
|  | (In millions)
Balance, January 1, 2015 |  | $ | 1,387 |  |  | $ | 841 |
Liabilities settled |  | (13 | ) |  | (8 | )
Accretion |  | 92 |  |  | 55 |
Revisions in estimated cash flows |  | (56 | ) |  | (57 | )
Balance, December 31, 2015 |  | $ | 1,410 |  |  | $ | 831 |
Liabilities settled |  | (27 | ) |  | (18 | )
Accretion |  | 95 |  |  | 56 |
Liabilities Incurred |  | 4 |  |  | 32 |
Balance, December 31, 2016 |  | $ | 1,482 |  |  | $ | 901 |

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