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Benefit Plans - Deferred Compensation Plan (Details) - USD ($) $ in Millions | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Dec. 31, 2017 | Jan. 01, 2017 | Dec. 31, 2016 | Jan. 01, 2016 | Jan. 01, 2015
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items] |  |  |  |  |
Interest rate earned on deferred amounts, prime rate first business day of year |  | 3.75% |  | 3.50% | 3.25%
Deferred compensation obligation | $ 3.4 |  | $ 3.2 |  |
Annual Salary | Management |  |  |  |  |
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items] |  |  |  |  |
Maximum percentage of compensation allowed to be deferred | 80.00% |  |  |  |
Deferred Bonus | Management |  |  |  |  |
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items] |  |  |  |  |
Maximum percentage of compensation allowed to be deferred | 100.00% |  |  |  |

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- Definition Deferred Compensation Arrangement with Individual, Maximum Elected Deferral by Employee, Percent + References No definition available. + Details
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- Definition Deferred Compensation Arrangement with Individual, Deferred Interest Earned, Percent + 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 The carrying amount of the liability as of the balance sheet date to an individual under a deferred compensation arrangement. This amount may be the result of periodic accruals made over the period of active employment, or reflect termination benefits resulting contractual terms or a death benefit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 710 -SubTopic 10 -Section 30 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363 + Details
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