Net Loss Per Share Attributable to Common Stockholders - Weighted-Average Common Stock Equivalents Excluded from Calculation of Diluted Net Loss Per Share as They Had Anti-Dilutive Effect (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted-average common stock equivalents excluded from calculation of diluted net loss per share	1,141,224	850,716	1,008,663	742,797
Vaccinex Products, LP Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted-average common stock equivalents excluded from calculation of diluted net loss per share		1,163,141	742,705	1,170,047
VX3
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted-average common stock equivalents excluded from calculation of diluted net loss per share		1,318,797	817,167	1,318,797