Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 62	$ 0
Operating expenses:
Research and development	51,388	35,789
Selling, general, and administrative	23,936	13,236
Total operating expenses	75,324	49,025
Loss from operations	(75,262)	(49,025)
Other income (expense):
Interest and other income, net	2,455	1,654
Interest expense	0	(13)
Total other income (expense), net	2,455	1,641
Net loss	$ (72,807)	$ (47,384)
Net loss per share—basic and diluted (in dollars per share)	$ (1.36)	$ (1.25)
Weighted average common shares outstanding—basic and diluted (in shares)	53,567,434	38,057,018
Comprehensive loss:
Net loss	$ (72,807)	$ (47,384)
Other comprehensive income (loss):
Unrealized gains (losses) on marketable securities	652	21
Total other comprehensive income (loss)	652	21
Total comprehensive loss	$ (72,155)	$ (47,363)