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Fair Value Measurements (Details) - Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] - Management [Member] - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016
Schedule of Trading Security [Line Items] |  |
Maximum percentage of participants' compensation which is deferrable (as a percent) | 100.00% |
Balance of the plan which was fully funded | $ 4.6 | $ 5.4

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- Definition Represents the maximum percentage of participants' compensation that is deferrable by participants under the deferred compensation plan. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Carrying amount as of the balance sheet date of assets held under deferred compensation agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Details
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