Revenues Revenues (Details Textual)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Distributor One
Disaggregation of Revenue [Line Items]
Percentage of revenues from major distributors	32.50%	34.30%	33.20%	35.50%
Distributor Two
Disaggregation of Revenue [Line Items]
Percentage of revenues from major distributors	18.60%	22.80%	17.30%	21.10%