Summary of Significant Accounting Policies - Computation of Earnings (Loss) per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Basic loss per share computation:
Net loss - basic	$ (12,866)	$ (14,332)	$ (10,713)	$ (41,168)
Net loss - diluted	$ (12,866)	$ (14,332)	$ (10,713)	$ (41,168)
Weighted average common shares - basic (in shares)	93,410,017	5,593,557	76,037,735	5,491,554
Weighted average common shares - diluted (in shares)	93,410,017	5,593,557	76,037,735	5,491,554
Basic loss per share (in dollars per share)	$ (0.14)	$ (2.56)	$ (0.14)	$ (7.50)
Diluted loss per share (in dollars per shares)	$ (0.14)	$ (2.56)	$ (0.14)	$ (7.50)