Operating Leases - Balance Sheet Presentation (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Balance Sheet Captions
Right-of-use assets	$ 492	$ 574
Operating lease liabilities, current	381	370
Operating lease liabilities	536	624
Other assets
Balance Sheet Captions
Right-of-use assets	492	574
Accrued liabilities
Balance Sheet Captions
Operating lease liabilities, current	381	370
Other long-term liabilities
Balance Sheet Captions
Operating lease liabilities, noncurrent	$ 155	$ 254