Commitments and Contingencies - Leases, Maturities of operating leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies
2021	$ 908
2022	444
Present value adjustment	(82)
Total lease liabilities	1,270
Less: current lease liabilities	$ (844)	$ (640)
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued Liabilities and Other Liabilities, Current	Accrued Liabilities and Other Liabilities, Current
Long term lease liabilities	$ 426	$ 1,251
Maximum days allowed for cancellation of contracts prior written notice	90 days