CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Convertible Preferred Shares	Common Shares Initial Public Offering	Common Shares Follow-On Offering	Common Shares Private Placement	Common Shares	Additional Paid-In Capital Initial Public Offering	Additional Paid-In Capital Follow-On Offering	Additional Paid-In Capital Private Placement	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Initial Public Offering	Follow-On Offering	Private Placement	Total
Balance at the beginning of the period at Dec. 31, 2017	$ 119,770
Balance at the beginning of the period (in shares) at Dec. 31, 2017	22,885,492
Changes in temporary equity
Issuance of Series C convertible preferred shares, net of issuance costs	$ 190,822
Issuance of Series C convertible preferred shares, net of issuance costs (in shares)	12,784,601
Conversion of convertible preferred shares to common shares	$ (310,592)
Conversion of convertible preferred shares to common shares (in shares)	(35,670,093)
Balance at the beginning of the period at Dec. 31, 2017					$ 1				$ 1,289		$ (90,998)				$ (89,708)
Balance at the beginning of the period (in shares) at Dec. 31, 2017					4,288,329
Changes in equity
Conversion of convertible preferred shares into common shares					$ 8				310,584						310,592
Conversion of convertible preferred shares into common shares (in shares)					35,670,093
Issuance of common shares upon completion of offering, net of placement agent fees		$ 4				$ 155,532						$ 155,536
Issuance of common shares upon completion of offering, net of placement agent fees (in shares)		9,484,202
Issuance of Class A shares under incentive award plans and employee share purchase plan									377						377
Issuance of Class A shares under incentive award plans and employee share purchase plan (in shares)					47,023
Share-based compensation expense									5,701						5,701
Unrealized gain on short-term investments										$ (4)					(4)
Net loss											(103,227)				(103,227)
Balance at the end of the period at Dec. 31, 2018					$ 13				473,483	(4)	(194,225)				279,267
Balance at the end of the period (in shares) at Dec. 31, 2018					49,489,647
Changes in equity
Issuance of common shares upon completion of offering, net of placement agent fees			$ 2				$ 48,474	$ 34,511					$ 48,476	$ 34,511
Issuance of common shares upon completion of offering, net of placement agent fees (in shares)			2,816,110	2,000,000
Common shares issued or to be issued in connection with the acquisition of all issued and outstanding equity securities of Primatope Therapeutics, Inc.									7,000						7,000
Common shares issued or to be issued in connection with the acquisition of all issued and outstanding equity securities of Primatope Therapeutics, Inc. (in shares)					337,008
Common shares issued or to be issued in connection with a milestone payment due to Primatope Therapeutics, Inc.									1,800						1,800
Common shares issued or to be issued in connection with a milestone payment due to Primatope Therapeutics, Inc. (in shares)					94,284
Issuance of Class A shares under incentive award plans and employee share purchase plan									1,119						1,119
Issuance of Class A shares under incentive award plans and employee share purchase plan (in shares)					200,579
Share-based compensation expense									15,080						15,080
Unrealized gain on short-term investments										37					37
Net loss											(161,867)				(161,867)
Balance at the end of the period at Dec. 31, 2019					$ 15				581,467	33	(356,092)				225,423
Balance at the end of the period (in shares) at Dec. 31, 2019					54,937,628
Changes in equity
Issuance of common shares upon completion of offering, net of placement agent fees			$ 2	$ 1			$ 164,586	$ 55,944					$ 164,588	$ 55,945
Issuance of common shares upon completion of offering, net of placement agent fees (in shares)			8,712,381	3,028,572
Common shares issued or to be issued in connection with the acquisition of all issued and outstanding equity securities of Primatope Therapeutics, Inc. (in shares)					76,103
Issuance of Class A shares under incentive award plans and employee share purchase plan									6,552						6,552
Issuance of Class A shares under incentive award plans and employee share purchase plan (in shares)					1,460,338
Share-based compensation expense									20,875						20,875
Unrealized gain on short-term investments										(67)					(67)
Net loss											(161,381)				(161,381)
Balance at the end of the period at Dec. 31, 2020					$ 18				$ 829,424	$ (34)	$ (517,473)				$ 311,935
Balance at the end of the period (in shares) at Dec. 31, 2020					68,215,022