Revenues - Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 28,202	$ 26,759
Instruments, equipment software and accessories [Member]
Disaggregation of Revenue [Line Items]
Revenues	26,757	25,604
Service, maintenance and warranty contracts [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,445	1,155
Segment, Geographical, United States [Member]
Disaggregation of Revenue [Line Items]
Revenues	19,814	17,043
Segment, Geographical, United States [Member] | Instruments, equipment software and accessories [Member]
Disaggregation of Revenue [Line Items]
Revenues	18,671	16,147
Segment, Geographical, United States [Member] | Service, maintenance and warranty contracts [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,143	896
Segment, Geographical, United Kingdom [Member]
Disaggregation of Revenue [Line Items]
Revenues	3,319	3,696
Segment, Geographical, United Kingdom [Member] | Instruments, equipment software and accessories [Member]
Disaggregation of Revenue [Line Items]
Revenues	3,129	3,495
Segment, Geographical, United Kingdom [Member] | Service, maintenance and warranty contracts [Member]
Disaggregation of Revenue [Line Items]
Revenues	190	201
Segment, Geographical, Germany [Member]
Disaggregation of Revenue [Line Items]
Revenues	3,010	3,759
Segment, Geographical, Germany [Member] | Instruments, equipment software and accessories [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,913	3,707
Segment, Geographical, Germany [Member] | Service, maintenance and warranty contracts [Member]
Disaggregation of Revenue [Line Items]
Revenues	97	52
Rest Of The World [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,059	2,261
Rest Of The World [Member] | Instruments, equipment software and accessories [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,044	2,255
Rest Of The World [Member] | Service, maintenance and warranty contracts [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 15	$ 6