Equity - Class A Common Shares Reserved for Future Issuance (Detail)	Dec. 31, 2020 shares
Class of Stock [Line Items]
Total shares reserved for future issuance	7,075,798
Class B Common Stock Converted Into Class A Common Stock [Member]
Class of Stock [Line Items]
Total shares reserved for future issuance	5,400,000
Stock Option [Member] | 2009 Plan [Member]
Class of Stock [Line Items]
Total shares reserved for future issuance	319,196
Reserved Under the ESPP [Member]
Class of Stock [Line Items]
Total shares reserved for future issuance	300,000
Restricted Stock Units [Member] | 2009 Plan [Member]
Class of Stock [Line Items]
Total shares reserved for future issuance	604,328
Restricted Stock Units [Member] | 2019 Plan [Member]
Class of Stock [Line Items]
Total shares reserved for future issuance	452,274