Equity - Class A Common Shares Reserved for Future Issuance (Detail)	Dec. 31, 2018 shares
Class of Stock [Line Items]
Total shares reserved for future issuance	6,984,225
Stock Option [Member]
Class of Stock [Line Items]
Total shares reserved for future issuance	496,557
Restricted Stock Units [Member]
Class of Stock [Line Items]
Total shares reserved for future issuance	1,087,668
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