The Company and a Summary of its Significant Accounting Policies - Additional Information (Details)		3 Months Ended		9 Months Ended
	Aug. 29, 2019	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Revenue_Stream Segment shares	Sep. 30, 2019 USD ($) shares	Dec. 31, 2019 USD ($)
The Company and Summary of its Significant Accounting Policies [Line Items]
Conversion ratio of reverse stock split	0.5			0.5
Description of reverse stock split of common stock				one-for-two
Depreciation expense		$ 200,000	$ 20,000	$ 306,000	$ 58,000
Disposal of plant or equipment		32,000	0
Impairment losses		0	0	0	0
Sweep account		11,500,000		11,500,000
Insured amount by FDIC		250,000		$ 250,000
Number of revenue streams | Revenue_Stream				2
Short-term deferred revenue		1,005,000		$ 1,005,000		$ 1,390,000
Long-term deferred revenue		679,000		679,000		0
Accounts receivable		1,007,000		$ 1,007,000		680,000
Number of operating segments | Segment				1
Stock-based compensation expense		1,400,000	$ 700,000	$ 3,500,000	$ 1,200,000
Compensation cost related to non-vested awards not yet recognized		13,600,000		$ 13,600,000
Weighted average term expected to be recognized				2 years 11 months 15 days
Fair value liabilities measured on recurring basis						0
Fair Value, Recurring
The Company and Summary of its Significant Accounting Policies [Line Items]
Fair value assets measured on recurring basis		39,984,000		$ 39,984,000		0
Conversion of Preferred Stock
The Company and Summary of its Significant Accounting Policies [Line Items]
Anti-dilutive equity instruments excluded from diluted net loss per share of common stock | shares					615,385
Common Stock Warrants
The Company and Summary of its Significant Accounting Policies [Line Items]
Anti-dilutive equity instruments excluded from diluted net loss per share of common stock | shares				4,114,148	4,226,785
Stock Options and Restricted Stock Units
The Company and Summary of its Significant Accounting Policies [Line Items]
Anti-dilutive equity instruments excluded from diluted net loss per share of common stock | shares				2,006,244	964,995
Assay Revenue
The Company and Summary of its Significant Accounting Policies [Line Items]
Accounts receivable gross		900,000		$ 900,000		500,000
Contract Revenue
The Company and Summary of its Significant Accounting Policies [Line Items]
Accounts receivable		$ 100,000		$ 100,000		$ 300,000
Minimum
The Company and Summary of its Significant Accounting Policies [Line Items]
Useful life of the assets				2 years
Minimum | Stock Options
The Company and Summary of its Significant Accounting Policies [Line Items]
Requisite service period				3 years
Minimum | Restricted Stock Units
The Company and Summary of its Significant Accounting Policies [Line Items]
Requisite service period				2 years
Maximum
The Company and Summary of its Significant Accounting Policies [Line Items]
Useful life of the assets				5 years
Maximum | Stock Options
The Company and Summary of its Significant Accounting Policies [Line Items]
Requisite service period				4 years
Maximum | Restricted Stock Units
The Company and Summary of its Significant Accounting Policies [Line Items]
Requisite service period				4 years