The Company and a Summary of its Significant Accounting Policies - Schedule of Revenues Disaggregated by Revenue Source (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation Of Revenue [Line Items]
Total Revenues	$ 1,362	$ 565	$ 3,764	$ 1,775
Assay Revenue, PLA Test
Disaggregation Of Revenue [Line Items]
Total Revenues	1,233	385	2,678	905
Contract Revenue, Adhesive Patch kits
Disaggregation Of Revenue [Line Items]
Total Revenues	67	101	106	436
Contract Revenue, RNA Extractions
Disaggregation Of Revenue [Line Items]
Total Revenues			764	200
Contract Revenue, Project Management Fees
Disaggregation Of Revenue [Line Items]
Total Revenues	$ 62	$ 79	$ 216	232
Contract Revenue, Other
Disaggregation Of Revenue [Line Items]
Total Revenues				$ 2