Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Prepaid Expenses and Other Current Assets.
Vendor prepayments and deposits	$ 1,831	$ 2,010
Prepaid insurance	740	1,026
Prepaid facility maintenance fee	343	336
Other receivables	330	3,985
Interest receivables and other current assets	181	174
Total prepaid expenses and other current assets	$ 3,425	$ 7,531