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Restricted Stock, Performance Share and Cash Awards (Tables) | 12 Months Ended
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Dec. 31, 2017
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Schedule of Restricted Stock Awards Vesting Periods | The vesting periods of the 2017, 2016 and 2015 restricted stock unit awards are as follows (in actual shares):
|  | Restricted Stock Units Granted |
Vesting Period |  | 2017 |  |  | 2016 |  |  | 2015 |
One year |  |  | 21,600 |  |  |  | 27,417 |  |  |  | 22,175 |
Four years |  |  | — |  |  |  | — |  |  |  | 9,200 |
Five years |  |  | 454,750 |  |  |  | 451,750 |  |  |  | 363,600 |
Total shares granted |  |  | 476,350 |  |  |  | 479,167 |  |  |  | 394,975 |

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