Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 16,014	$ 11,474
Accumulated depreciation	(8,711)	(6,584)
Net property and equipment	7,303	4,890
Systems reclassified from inventory	1,900
Depreciation expense	2,500	2,200	$ 2,300
Inventory Transfers
Property, Plant and Equipment [Line Items]
Systems reclassified from inventory	100
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	2,700	2,756
Technical equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	3,868	3,348
Facilities
Property, Plant and Equipment [Line Items]
Total property and equipment	4,037	3,621
Instruments
Property, Plant and Equipment [Line Items]
Total property and equipment	5,318	1,400
Capital projects in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 91	$ 349