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Share-based Payments Share-based Payments (Details Textual) | 3 Months Ended
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Mar. 31, 2018 $ / shares shares
Performance stock units settled in stock |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Percentage of earnings of the target number of units granted based on actual stock performance (Minimum) | 0.00%
Percentage of earnings of the target number of units granted based on actual stock performance (Maximum) | 200.00%
Number of shares granted | 66,000
Weighted average grant date fair value | $ / shares | $ 317.58
Performance stock units settled in cash |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Percentage of earnings of the target number of units granted based on actual stock performance (Minimum) | 0.00%
Percentage of earnings of the target number of units granted based on actual stock performance (Maximum) | 200.00%
Number of shares granted | 44,000
Number of days for calculation of average closing stock price | 30 days

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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + 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)(iii)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + 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)(iii)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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