Nature of the Business and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended			12 Months Ended
	Feb. 29, 2020	Jun. 30, 2018	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2019
Nature Of Business And Basis Of Presentation [Line Items]
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs			$ 188,385
Net loss			(72,807)		$ (47,384)	$ (192,300)
Accumulated deficit			$ (560,786)			$ (487,979)
Common Stock
Nature Of Business And Basis Of Presentation [Line Items]
Number of shares issued and sold (in shares)			3,659,090
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs			$ 37
Follow on Offering | Common Stock
Nature Of Business And Basis Of Presentation [Line Items]
Number of shares issued and sold (in shares)	3,659,090	4,945,000		12,432,431
Additional offering price of common stock (in dollars per share)	$ 55.00	$ 40.00		$ 37.00
Issuance of common stock sold in public offering, net of underwriting discounts, commissions and offering costs	$ 188,400	$ 185,300		$ 431,800