Stockholders' Equity - Equity offerings (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Nov. 30, 2019	Sep. 30, 2020
Class of Warrant or Right [Line Items]
Net proceeds from issuance after deducting underwriting discounts, commissions and other offering expenses	$ 107,782	$ 85,598
Underwriting discounts, commissions and other offering expenses		$ 5,814
Number of common stocks are exercisable from the November 2019 Pre-Funded Warrants and the June 2020 Pre-Funded Warrants				3,721,738
Pre-Funded Warrants
Class of Warrant or Right [Line Items]
Issuance of pre-funded warrants (in shares)	1,521,738		2,200,000
Pre-funded warrants exercise price	$ 22.9999		$ 13.6099
Variation between public offering prices of common stock and Pre-Funded Warrants	$ 0.0001		$ 0.0001
Maximum percentage of holding for exercise warrants	9.99%		9.99%
Prior notice period to change percentage of holding	61 days		61 days
Maximum percentage of increase (decrease) of holding for exercise warrants	19.99%
Number of warrants exercised	0		0
Underwriter rights
Class of Warrant or Right [Line Items]
Number of shares issued	2,826,088	838,530	3,678,031
Public offering price	$ 23.00		$ 13.61
Shares issued during period	652,173
Underwriting discounts, commissions and other offering expenses	$ 7,217