Accounts Payable and Accrued Expenses (Schedule of Accounts Payable and Accrued Expenses) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accounts Payable and Accrued Expenses
Accounts payable	$ 3,512	$ 3,518
Research and development	3,083	2,862
Accrued compensation	2,595	2,009
Other	554	358
Total accounts payable and accrued expenses	$ 9,744	$ 8,747