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Employee Benefit Plans - Profit Sharing and Savings Plans (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits |  |  |
Eligibility requirement, service hours to be completed | 20 hours |  |
Deferred Profit Sharing |  |  |
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits |  |  |
Eligibility requirement, requisite service period | 3 years |  |
Compensation expense | $ 1,600,000 | $ 2,700,000 | $ 700,000
Savings Plan, Employee Elected |  |  |
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits |  |  |
Compensation expense | 5,500,000 | $ 4,800,000 | $ 4,700,000
Maximum annual contribution per employee, amount per dollar of employee contribution | $ 1.25 |  |
Maximum annual contribution per employee, percent | 4.00% |  |

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- Definition Deferred Compensation Arrangement with Individual, Maximum Annual Contribution Per Employee, Amount Per Dollar of Employee Contribution + References No definition available. + Details
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- Definition Deferred Compensation Arrangement with Individual, Maximum Annual Contribution Per Employee, Percent + References No definition available. + Details
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- Definition Deferred Compensation Arrangement with Individual, Required Service Hours + References No definition available. + Details
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- Definition The compensation expense recognized during the period pertaining to the deferred compensation arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901 Reference 2: 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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- 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 Minimum period the individual is required to perform services to be fully vested under the deferred compensation arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 710 -SubTopic 10 -Section 55 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6409961&loc=d3e20487-108367 Reference 2: 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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