Property and Equipment, net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property and equipment-at cost:
Total property and equipment-at cost	$ 43,057	$ 39,537
Less accumulated depreciation	(21,987)	(16,956)
Net property and equipment	21,070	22,581
Plant and machinery
Property and equipment-at cost:
Total property and equipment-at cost	15,206	13,762
Instruments
Property and equipment-at cost:
Total property and equipment-at cost	15,089	13,347
Office equipment
Property and equipment-at cost:
Total property and equipment-at cost	2,114	1,948
Leasehold improvements
Property and equipment-at cost:
Total property and equipment-at cost	$ 10,648	$ 10,480