Revenues Revenues (Details Textual)	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Distributor One
Disaggregation of Revenue [Line Items]
Percentage of revenues from major distributors	30.70%	33.70%	32.40%	34.90%
Distributor Two
Disaggregation of Revenue [Line Items]
Percentage of revenues from major distributors	19.30%	20.80%	18.00%	21.00%

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.

No definition available.

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