Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating expenses:
Research and development	$ 35,308	$ 8,584	$ 58,069	$ 20,870
Selling, general, and administrative	8,841	6,437	16,600	11,152
Total operating expenses	44,149	15,021	74,669	32,022
Loss from operations	(44,149)	(15,021)	(74,669)	(32,022)
Other income (expense):
Interest income, net	1,353	609	2,899	1,151
Total other income:	1,353	609	2,899	1,151
Net loss and comprehensive loss	(42,796)	(14,412)	(71,770)	(30,871)
Net loss attributable to common stockholders	$ (42,796)	$ (14,412)	$ (71,770)	$ (30,871)
Net loss per share attributable to common stockholders, basic and diluted	$ (1.24)	$ (0.52)	$ (2.08)	$ (1.12)
Weighted average common shares outstanding, basic and diluted	34,452,661	27,960,664	34,435,023	27,624,271