Organization and Summary of significant accounting policies (Narrative) (Details) $ in Thousands, € in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) segment	Jun. 30, 2016 USD ($)	Jun. 30, 2015 segment	Feb. 19, 2016 EUR (€)	Feb. 19, 2016 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of business segments | segment				1		2
Total share-based compensation expense	$ 389		$ 350	$ 804	$ 697
Tecnonet [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Working capital adjustment							€ 4.3	$ 4,800
Accounting Standards Update 2016-09 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total share-based compensation expense		$ 57