Annual report pursuant to Section 13 and 15(d)

Balance Sheets Details

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Balance Sheets Details
12 Months Ended
Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]  
Balance Sheets Details Balance Sheets Details
Accounts receivable
The following is a summary of activity in our allowance for doubtful accounts for the periods presented (in thousands):
December 31,
2019 2018 2017
Allowance - beginning of period $ (34)   $ (34)   $ (421)  
Write-offs and other (1)
—    —    387   
Allowance - end of period $ (34)   $ (34)   $ (34)  
(1) The change in allowance for doubtful accounts was mainly related to the write-off of receivables from a foreign customer.
Inventories
Inventories consisted of the following (in thousands): 
  December 31,
  2019 2018
Raw materials $   $ 165   
Work in process 26    47   
Finished goods 338    377   
Inventories $ 371    $ 589   

Property and Equipment, net
Property and equipment, net consisted of the following (in thousands): 
  December 31,
  2019 2018
Laboratory equipment (1)
$ 23,561    $ 21,328   
Leasehold improvements 10,804    10,359   
Computer equipment and software 3,016    3,954   
Office equipment and furniture 1,461    1,272   
Construction in progress (2)
691    939   
Property and equipment 39,533    37,852   
Less: accumulated depreciation and amortization (33,251)   (33,093)  
Property and equipment, net $ 6,282    $ 4,759   
(1) Fully depreciated laboratory equipment with a cost of $1.0 million and $0.3 million were retired during the year ended December 31, 2019 and 2018, respectively.
(2) Construction in progress includes equipment received but not yet placed into service pending installation.

Goodwill
Goodwill had a carrying value of approximately of $3.2 million as of December 31, 2019 and 2018.
Other Accrued Liabilities
Other accrued liabilities consisted of the following (in thousands): 
  December 31,
  2019 2018
Accrued purchases 4,386    $ 1,492   
Accrued professional and outside service fees 1,802    2,020   
Deferred rent —    343   
Lease incentive obligation —    425   
Other 352    575   
Total
$ 6,540    $ 4,855