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Share-Based Compensation (Tables) | 3 Months Ended
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Mar. 31, 2018
Shares awarded to non-employee directors [Line Items] |
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan | The table below presents the amounts included in net income related to share-based compensation expense for the three months ended March 31, 2018 and 2017:
|  | Three Months Ended
|  | March 31,
|  | 2018 |  | 2017
(in thousands) |  |  |  |
Awards to non-employee directors |  | $ | 135 |  |  | $ | 135 |
Awards to key employees |  | 1,385 |  |  | 504 |
Total compensation expense |  | 1,520 |  |  | 639 |
Less: tax benefit |  | (416 | ) |  | (257 | )
Share-based compensation amounts included in net income |  | $ | 1,104 |  |  | $ | 382 |
Award to key employees [Member] |
Shares awarded to non-employee directors [Line Items] |
Schedule of Share-based Compensation, Activity | The table below presents the summary of the stock activity for awards to key employees for the three months ended March 31, 2018:
|  | Number of Shares |  | Weighted Average Fair Value
Outstanding—December 31, 2017 |  | 132,642 |  |  | $ | 59.31 |
Granted |  | 49,494 |  |  | $ | 67.76 |
Vested |  | (29,786 | ) |  | $ | 47.39 |
Expired |  | (3,933 | ) |  | $ | 49.66 |
Outstanding—March 31, 2018 |  | 148,417 |  |  | $ | 66.53 |

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- Definition Tabular disclosure of the amount of total share-based compensation cost, including the amounts attributable to each share-based compensation plan and any related tax benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition Tabular disclosure for share-based compensation plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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