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, 2018	$ 3	$ 225,352	$ 7	$ (84,835)	$ 140,527
Balance at the beginning of period (in shares) at Dec. 31, 2018	34,193,666
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense		864			864
Foreign currency translation			56		56
Net loss				(15,934)	(15,934)
Balance at the end of period at Mar. 31, 2019	$ 3	226,216	63	(100,769)	125,513
Balance at the end of period (in shares) at Mar. 31, 2019	34,193,666
Balance at the beginning of period at Dec. 31, 2018	$ 3	225,352	7	(84,835)	140,527
Balance at the beginning of period (in shares) at Dec. 31, 2018	34,193,666
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
Increase (Decrease) in Stockholders' Equity
Exercise of stock options		370			$ 370
Exercise of stock options (in shares)	25,778				25,778
Stock-based compensation expense		2,211			$ 2,211
Stock-based compensation expense (in shares)	3,429
Foreign currency translation			25		25
Net loss				(26,179)	(26,179)
Balance at the end of period at Mar. 31, 2020	$ 4	$ 367,293	$ 75	$ (192,042)	$ 175,330
Balance at the end of period (in shares) at Mar. 31, 2020	39,757,623