Summary of Significant Accounting Policies - Disaggregation of Revenue by Major Resource (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Total revenue	$ 1,804	$ 3,931	$ 3,589	$ 6,242
Product Instruments [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	462	488	997	709
Total Product Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	1,274	1,220	2,588	2,268
Product Consumables [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	717	575	1,450	1,321
Research [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	71	2,711	213	3,974
Instrument Rentals [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	95	$ 157	141	$ 238
Contribution Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	$ 459		$ 788