Supplemental Balance Sheet Information - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 19,595	$ 18,622
Less accumulated depreciation and amortization	(12,333)	(11,307)
Property and equipment, net	7,262	7,315
Office and Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	409	409
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	762	751
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,747	4,636
Furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	194	200
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	695	695
Manufacturing Tooling and Molds [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	255	255
T2-Owned Instruments and Components [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	7,483	6,796
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,461	3,437
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,589	$ 1,443

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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