Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss)/Income	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
Stock-based compensation expense		172			172
Foreign currency translation			3		3
Net loss				(7,483)	(7,483)
Balance at the end of period at Mar. 31, 2018	$ 3	124,051	(166)	(49,044)	74,844
Balance at the end of period (in shares) at Mar. 31, 2018	26,749,666
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
Net loss					(17,788)
Balance at the end of period at Jun. 30, 2018	$ 3	124,955	(88)	(59,349)	65,521
Balance at the end of period (in shares) at Jun. 30, 2018	26,749,666
Balance at the beginning of period at Mar. 31, 2018	$ 3	124,051	(166)	(49,044)	74,844
Balance at the beginning of period (in shares) at Mar. 31, 2018	26,749,666
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense		904			904
Foreign currency translation			78		78
Net loss				(10,305)	(10,305)
Balance at the end of period at Jun. 30, 2018	$ 3	124,955	(88)	(59,349)	65,521
Balance at the end of period (in shares) at Jun. 30, 2018	26,749,666
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				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				34,193,666
Increase (Decrease) in Stockholders' Equity
Net loss					$ (33,970)
Balance at the end of period at Jun. 30, 2019	$ 3	227,187	(3)	(118,805)	$ 108,382
Balance at the end of period (in shares) at Jun. 30, 2019	34,193,666				34,193,666
Balance at the beginning of period at Mar. 31, 2019	$ 3	226,216	63	(100,769)	$ 125,513
Balance at the beginning of period (in shares) at Mar. 31, 2019	34,193,666
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense		971			971
Foreign currency translation			(66)		(66)
Net loss				(18,036)	(18,036)
Balance at the end of period at Jun. 30, 2019	$ 3	$ 227,187	$ (3)	$ (118,805)	$ 108,382
Balance at the end of period (in shares) at Jun. 30, 2019	34,193,666				34,193,666