Segment reporting and concentrations (Details Textual)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts Receivable [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	10.00%
Foreign Customer [Member] | Sales Revenue, Net [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	49.00%	51.00%	47.00%
Foreign Customer [Member] | Accounts Receivable [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	73.00%	62.00%
Two clients [Member] | Sales Revenue, Net [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	31.00%	33.00%	31.00%
Four Clients [Member] | Accounts Receivable [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	52.00%	68.00%
One Other Client [Member] | Sales Revenue, Net [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage			10.00%
Concentration Risk, Customer	less than 10%	less than 10%