Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	2019 Sales Agreement [Member]	2022 Sales Agreement [Member]	Follow On Public Offering	At The Market Offerings	At The Market Offerings 2019 Sales Agreement [Member]	At The Market Offerings 2022 Sales Agreement [Member]	Regeneron Pharmaceuticals Inc. [Member]	Follow-on Offering [Member]	Follow-on Offering [Member] Follow On Public Offering	Follow-on Offering [Member] At The Market Offerings	Follow-on Offering [Member] At The Market Offerings 2019 Sales Agreement [Member]	Follow-on Offering [Member] At The Market Offerings 2022 Sales Agreement [Member]	Follow-on Offering [Member] Regeneron Pharmaceuticals Inc. [Member]	Additional Paid-In Capital	Additional Paid-In Capital Follow On Public Offering	Additional Paid-In Capital At The Market Offerings	Additional Paid-In Capital At The Market Offerings 2019 Sales Agreement [Member]	Additional Paid-In Capital At The Market Offerings 2022 Sales Agreement [Member]	Additional Paid-In Capital Regeneron Pharmaceuticals Inc. [Member]	Accumulated Other Comprehensive Income	Retained Earnings
Beginning balance at Dec. 31, 2019	$ 269,881								$ 5						$ 570,493						$ 261	$ (300,878)
Beginning balance, shares at Dec. 31, 2019									50,198,044
Issuance of common stock				$ 296,607	$ 49,461			$ 12,580		$ 2						$ 296,605	$ 49,461			$ 12,580
Issuance of common stock, shares		2,270,161								11,815,069	2,270,161			925,218
Exercise of stock options	$ 11,574														11,574
Exercise of stock options, shares	840,824
Vesting of restricted stock units, shares	82,829
Issuance of shares under employee stock purchase plan	$ 1,557														1,557
Issuance of shares under employee stock purchase plan, shares	101,911
Equity-based compensation	$ 19,903														19,903
Other comprehensive income - unrealized gain (loss) on marketable securities	(260)																				(260)
Net loss	(134,231)
Ending balance at Dec. 31, 2020	527,072								$ 7						962,173						1	(435,109)
Ending balance, shares at Dec. 31, 2020									66,234,056
Issuance of common stock				648,315	$ 45,255											648,315	$ 45,255
Issuance of common stock, shares		641,709								4,758,620	641,709
Exercise of stock options	$ 41,094														41,094
Exercise of stock options, shares	2,700,886
Vesting of restricted stock units, shares	119,715
Issuance of shares under employee stock purchase plan	$ 2,024														2,024
Issuance of shares under employee stock purchase plan, shares	30,897
Equity-based compensation	$ 47,009														47,009
Other comprehensive income - unrealized gain (loss) on marketable securities	(2,126)																				(2,126)
Other comprehensive loss - equity method investment	(507)
Net loss	(267,892)
Ending balance at Dec. 31, 2021	$ 1,040,244								$ 7						1,745,870						(2,632)	(703,001)
Ending balance, shares at Dec. 31, 2021	74,485,883								74,485,883
Issuance of common stock				$ 337,892		$ 38,886	$ 189,011			$ 1		$ 1				$ 337,891		$ 38,885	$ 189,011
Issuance of common stock, shares			3,395,339			579,788				7,532,751			3,395,339
Exercise of stock options	$ 14,517														14,517
Exercise of stock options, shares	883,954								883,954
Vesting of restricted stock units									$ 147,674
Issuance of shares under employee stock purchase plan	$ 2,649								77,618						2,649
Equity-based compensation	91,400
Other comprehensive income - unrealized gain (loss) on marketable securities	(1,637)																				(1,637)
Other comprehensive loss - equity method investment	(3,192)																				(3,192)
Net loss	(474,186)
Ending balance at Dec. 31, 2022	$ 1,235,584								$ 9						$ 2,420,223						$ (7,461)	$ (1,177,187)
Ending balance, shares at Dec. 31, 2022	87,103,007								87,103,007