Balance Sheet Items - Prepaid Expenses and Other Current Assets (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Prepaid expenses	$ 643,000	$ 949,000
Prepaid research and development costs	622,000	632,000
Other current assets	691,000	553,000
Total	$ 1,956,000	$ 2,134,000	$ 2,134,000

Amount of asset related to consideration paid in advance for costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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Name:	us-gaap_PrepaidExpenseCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant