Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income/(Loss)	Accumulated Deficit	Total
Balance at the beginning of period at Dec. 31, 2017	$ 3	$ 123,879	$ (169)	$ (41,561)	$ 82,152
Balance at the beginning of period (in shares) at Dec. 31, 2017	26,749,666
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, Stock offering, net of issuance costs		99,507			99,507
Issuance of common stock, Stock offering (in shares)	6,900,000
Issuance of common stock to nonemployees (in shares)	544,000
Stock-based compensation expense		1,966			1,966
Foreign currency translation			176		176
Net loss				(43,274)	(43,274)
Balance at the end of period at Dec. 31, 2018	$ 3	225,352	7	(84,835)	140,527
Balance at the end of period (in shares) at Dec. 31, 2018	34,193,666
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, Stock offering, net of issuance costs	$ 1	134,703			134,704
Issuance of common stock, Stock offering (in shares)	5,134,750
Issuance of common stock to nonemployees (in shares)	400,000
Stock-based compensation expense		4,657			4,657
Foreign currency translation			43		43
Net loss				(81,028)	(81,028)
Balance at the end of period at Dec. 31, 2019	$ 4	$ 364,712	$ 50	$ (165,863)	$ 198,903
Balance at the end of period (in shares) at Dec. 31, 2019	39,728,416