Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Gross margin	$ 7,065	$ 0
Cost of product sales	1,588	0
Gross margin	5,477	0
Operating expenses:
Research and development	10,099	16,832
Selling, general and administrative	95,618	31,698
Total operating expenses	105,717	48,530
Loss from operations	(100,240)	(48,530)
Other (income) expense:
Grant and other income	(406)	(162)
Interest income	(2,453)	(303)
Interest expense	9,229	910
Foreign currency (gains) losses	48	(73)
Net loss	(106,658)	(48,902)
Deemed dividend	0	11,969
Accretion to redemption value	0	1,096
Net loss attributable to common stockholders	$ (106,658)	$ (61,967)
Net loss per share of common stock,
basic (in USD per share)	$ (2.68)	$ (5.63)
diluted (in USD per share)	$ (2.68)	$ (5.63)
Weighted average common shares outstanding,
basic (in shares)	39,765,983	10,999,121
diluted (in shares)	39,765,983	10,999,121