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Business Segments (Revenue by Geography) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets |  |  |
Net Sales | $ 536,377 | $ 483,514 | $ 624,523
United States |  |  |
Revenues from External Customers and Long-Lived Assets |  |  |
Net Sales | 431,868 | 390,930 | 522,404
Canada |  |  |
Revenues from External Customers and Long-Lived Assets |  |  |
Net Sales | 38,859 | 30,644 | 40,545
United Kingdom |  |  |
Revenues from External Customers and Long-Lived Assets |  |  |
Net Sales | 37,237 | 37,188 | 26,817
Other |  |  |
Revenues from External Customers and Long-Lived Assets |  |  |
Net Sales | $ 28,413 | $ 24,752 | $ 34,757

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- Definition Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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