Net Loss per Share - Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares excluded from computation of diluted net income per share attributable to common stockholders (in shares)	12,012,308	9,624,582
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares excluded from computation of diluted net income per share attributable to common stockholders (in shares)	8,968,131	7,194,670
Shares to be issued under the 2018 ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares excluded from computation of diluted net income per share attributable to common stockholders (in shares)	1,500,500	1,111,998
RSU's issued and expecting to vest
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares excluded from computation of diluted net income per share attributable to common stockholders (in shares)	711,000	997,400
Shares available from conversion of note payable
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares excluded from computation of diluted net income per share attributable to common stockholders (in shares)	832,677	320,514