Balance Sheets Details (Tables)

12 Months Ended

Dec. 31, 2020

Balance Sheet Related Disclosures [Abstract]

Schedule of Cash and Cash Equivalents

Cash equivalents at December 31, 2020 and 2019 consisted of the following (in thousands): 

	December 31, 2020				December 31, 2019
	Adjusted Cost		Estimated Fair Value		Adjusted Cost		Estimated Fair Value
Money market funds (1) (2)	$	127,567	$	127,567	$	71,248	$	71,248

(1) Money market funds are classified in cash and cash equivalents on our consolidated balance sheets.

(2) Average Contractual Maturities (in days) is not applicable.

Schedule of Inventory Components

Inventories consisted of the following (in thousands): 

	December 31,
	2020		2019
Raw materials	$	77	$	7
Work in process	82		26
Finished goods	805		338
Inventories	$	964	$	371

Property and Equipment, Net

Property, equipment and leasehold improvements are stated at cost less accumulated depreciation and amortization and depreciated using the straight-line method over their estimated useful lives as follows:

Asset classification	Estimated useful life
Laboratory equipment	5 years
Computer equipment and software	3 to 5 years
Office equipment and furniture	5 years
Leasehold improvements	Lesser of useful life or lease term

Property and equipment, net consisted of the following (in thousands): 

	December 31,
	2020		2019
Laboratory equipment (1)	$	25,468	$	23,561
Leasehold improvements	10,785		10,804
Computer equipment and software	3,192		3,016
Office equipment and furniture	1,246		1,461
Construction in progress (2)	2,357		691
Property and equipment	43,048		39,533
Less: accumulated depreciation and amortization	(33,373)		(33,251)
Property and equipment, net	$	9,675	$	6,282

(1) Fully depreciated property and equipment with a cost of $1.8 million and $1.0 million were retired during the years ended December 31, 2020 and 2019, respectively.

(2) Construction in progress includes equipment received but not yet placed into service pending installation.

Depreciation expense included in the consolidated statements of operations as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018
Depreciation expense	$	1,950	$	1,570	$	1,147

Schedule of Accrued Liabilities

Other accrued liabilities consisted of the following (in thousands): 

	December 31,
	2020		2019
Accrued purchases	$	7,170	$	4,386
Accrued professional and outside service fees	2,589		1,802
Other	513		352
Total	$	10,272	$	6,540