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			6 Months Ended		12 Months Ended
	Feb. 29, 2020	Jun. 30, 2018	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 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			$ (67,241)		$ (21,460)	(140,048)	$ (68,844)	$ (192,300)
Accumulated deficit			(628,027)			(628,027)		$ (487,979)
Accounts Receivable, Credit Loss Expense (Reversal)			$ 0			$ 0
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