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Stock-Based Compensation (Tables) | 3 Months Ended
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Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
Summary of Restricted Stock Units Activity | RSU activity for the three months ended March 31, 2018 is summarized as follows:
| Number of Shares |  | Weighted Average Grant Date Fair Value
Outstanding at December 31, 2017 | 483,021 |  |  | $ | 104.16 |
Granted | 92,681 |  |  | $ | 139.49 |
Settled | (75,142 | ) |  | $ | 109.85 |
Outstanding at March 31, 2018 | 500,560 |  |  | $ | 109.95 |
Summary of Stock Option Activity | Stock option activity for the three months ended March 31, 2018 is summarized as follows:
| Number of Shares |  | Weighted Average Exercise Price
Outstanding at December 31, 2017 | 109,808 |  |  | $ | 16.44 |
Exercised | (22,245 | ) |  | $ | 31.38 |
Outstanding at March 31, 2018 | 87,563 |  |  | $ | 12.64 |

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- Definition Tabular disclosure for stock option 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 (d) -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 (e) -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 (c)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition Disclosure of the number and weighted-average grant date fair value for restricted stock and restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock and restricted stock units that were granted, vested, or forfeited during the year. + References No definition available. + Details
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