A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

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Primarily represents commissions incurred in the period based upon the sale by commissioned employees or third parties of the entity's goods or services, and fees for sales assistance or product enhancements performed by third parties (such as a distributor or value added reseller).

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Revenues (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018
Revenue from Contract with Customer [Abstract]
Allowance for Doubtful Accounts Receivable, Current	$ 2,700		$ 2,700
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					$ 400
Disaggregation of Revenue [Line Items]
Selling and administrative expense	84,983	$ 80,807	259,156	$ 259,396
Sales Revenue, Net [Member]
Disaggregation of Revenue [Line Items]
Sales Commissions and Fees	$ 2,400		6,300
Selling and Administrative Expenses [Member]
Disaggregation of Revenue [Line Items]
Sales Commissions and Fees		$ 2,000		5,800
Shipping and Handling [Member]
Disaggregation of Revenue [Line Items]
Selling and administrative expense			$ 10,000	$ 9,600