Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net loss attributable to common shareholders	$ (161,381)	$ (161,867)	$ (103,227)
Denominator:
Weighted average common shares outstanding - basic and diluted	61,842,722	54,049,477	29,547,427
Net loss per share attributable to common shareholders - basic and diluted	$ (2.61)	$ (2.99)	$ (3.49)