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Basis of Presentation and Significant Accounting Policies Incentive Compensation (Details) | 12 Months Ended
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Dec. 31, 2017
Twelve Months from Award Date [Domain] |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 50.00%
Twenty Four Months from Award Date [Domain] |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 50.00%

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- Definition Percentage of vesting of share-based compensation awards. + 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 (a)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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