Summary of Significant Accounting Policies - Financial Instruments Measured at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Liabilities:
Warrant liability	$ 1,836	$ 1,614
Fair Value, Recurring
Assets:
Digital currencies	773
Total	773
Liabilities:
Warrant liability	1,836	1,614
Total	1,836	1,614
Level 1 | Fair Value, Recurring
Assets:
Digital currencies	773
Total	773
Liabilities:
Warrant liability	0	0
Total	0	0
Level 2 | Fair Value, Recurring
Assets:
Digital currencies	0
Total	0
Liabilities:
Warrant liability	1,836	1,614
Total	1,836	1,614
Level 3 | Fair Value, Recurring
Assets:
Digital currencies	0
Total	0
Liabilities:
Warrant liability	0	0
Total	$ 0	$ 0