Summary of Significant Accounting Policies - Summary of reconciliation of shares used to determine net loss per share (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Summary of Significant Accounting Policies
Net income (loss)	$ 2,386	$ (13,797)	$ (499)	$ (17,836)
Weighted average number of shares - basic	42,628,560	42,604,189	42,628,560	42,603,315
Shares underlying options	289,002
Weighted average number of shares - diluted	42,917,562	42,604,189	42,628,560	42,603,315