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Valuation and Qualifying Accounts (Narrative) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Reserves for sales discounts | $ 15,652 | $ 13,488
Inventory obsolescence reserves | $ 6,932 | 7,262
Inventory usage period | 3 years |
Inventory reserve percentage | 100.00% |
Product warranty accrual period of expenses used in calculation | 12 months |
Product warranty accrual period for sales used in calculation | 12 months |
Warranty | $ 5,335 | $ 5,262
Parts |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Product warranty period | 90 days |
Minimum |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Sales discount percentage of customers who qualify for each program that discount available | 85.00% |
Product warranty accrual lag period | 90 days |
Maximum |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Sales discount percentage of customers who qualify for each program that discount available | 95.00% |
Product warranty accrual lag period | 6 months |
Maximum | Wholegood Units |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Product warranty period | 1 year |

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- Definition Amount of valuation reserve for inventory. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB TOPIC 5.BB) -URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.6(a)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section 35 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=68049868&loc=d3e3927-108312 + Details
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- Definition Carrying value as of the balance sheet date of obligations incurred through that date and payable for estimated claims under standard and extended warranty protection rights granted to customers. For classified balance sheets, represents the current portion of the liabilities (due within one year or within the normal operating cycle if longer). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 25 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=68070138&loc=d3e11281-110244 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=68068213&loc=d3e12524-110249 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.20) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Aggregate cash discounts given by the entity for goods sold to customers including, but not limited to, early payments of accounts due. For example, selling terms of "2/10, net 30" entitle a customer to a 2% discount for prompt payment within 10 days, otherwise full payment is expected in 30 days. Discounts are a deduction from gross revenue in arriving at net revenue. + 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(a)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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