Convertible Preferred Stock and Stockholders' Deficit - Additional Information (Details)	6 Months Ended
	Jun. 30, 2020 USD ($) Vote $ / shares shares	Jun. 30, 2019 USD ($)	Dec. 31, 2019 shares	Sep. 17, 2018 shares
Class Of Stock [Line Items]
Number of shares issued	6,559,348		6,502,929
Common stock, voting rights	The holders of the common stock are entitled to one vote for each share of common stock held at all meetings of stockholders (and written actions in lieu of meetings), and there are not any cumulative voting rights.
Percentage of non-cumulative dividends	8.00%
Preferred stock, purchase price | $		$ 121,253,000
ElevateBio, LLC
Class Of Stock [Line Items]
Preferred stock, purchase price | $	$ 20,000,000
Series A Preferred Stock
Class Of Stock [Line Items]
Shares issued, price per share | $ / shares	$ 1.50
Conversion price per share | $ / shares	2.24
Series B Preferred Stock
Class Of Stock [Line Items]
Shares issued, price per share | $ / shares	8.15
Conversion price per share | $ / shares	$ 12.15
Minimum
Class Of Stock [Line Items]
Proceeds from issuance of preferred stock | $	$ 100,000,000
2018 Equity Incentive Plan
Class Of Stock [Line Items]
Number of shares available for grant	7,033,971			7,033,971
Number of shares vested	2,801,859
Number of shares granted	6,658,878
Common Stock
Class Of Stock [Line Items]
Number of votes for each share | Vote	1
Common Stock | 2018 Equity Incentive Plan | Maximum
Class Of Stock [Line Items]
Number of shares available for grant				7,033,971
Managing Member of LLC
Class Of Stock [Line Items]
Number of shares issued				1