Annual report pursuant to Section 13 and 15(d)

Equity (Detail)

v3.20.2
Equity (Detail)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
May 24, 2019
USD ($)
Jun. 30, 2020
USD ($)
$ / shares
shares
Sep. 30, 2019
USD ($)
$ / shares
shares
Sep. 30, 2020
voting_rights
shares
Sep. 30, 2019
$ / shares
shares
Schedule Of Stockholders Equity [Line Items]          
Common stock, shares issued (in shares)       22,106,961  
Common stock, shares outstanding (in shares)     19,184,009   19,184,009
Common stock shares subject to registration rights (in shares)       22,235,744  
Common stock shares previously registered but not yet sold (in shares)       4,848,010  
Class B Common Stock          
Schedule Of Stockholders Equity [Line Items]          
Voting rights for each share | voting_rights       10  
Initial public offering (in shares)       1,278,148  
Common stock, shares issued (in shares)       20,828,813  
Common stock, shares outstanding (in shares)     17,905,861 17,905,861 17,905,861
Restricted shares exercised (in shares)       0  
Class A Common Stock          
Schedule Of Stockholders Equity [Line Items]          
Voting rights for each share | voting_rights       1  
Conversion rate       1  
Common stock, shares issued (in shares)     32,597,736 33,875,884 32,597,736
Common stock, shares outstanding (in shares)     32,597,736 33,875,884 32,597,736
Shares issued, price per share (in dollars per share) | $ / shares     $ 14.25   $ 14.25
Restricted shares exercised (in shares)       0  
Shares issued (in shares)       0  
Compensation expense | $     $ 700    
Over-Allotment Option | Class A Common Stock          
Schedule Of Stockholders Equity [Line Items]          
Issuance of stock (in shares)     5,000,000    
Secondary Offering | Class A Common Stock          
Schedule Of Stockholders Equity [Line Items]          
Exercised option for additional shares (in shares)   862,500 750,000   750,000
Common stock shares sold (in shares)   5,750,000      
Sale of stock (in dollars per share) | $ / shares   $ 16.50      
Payments of stock issuance costs | $   $ 200      
Director          
Schedule Of Stockholders Equity [Line Items]          
Amount of limit of dollar value of equity-based awards | $ $ 750        
2018 Equity Incentive Plan | Class B Common Stock          
Schedule Of Stockholders Equity [Line Items]          
Conversion of stock, shares issued (in shares)         74,592
Shares issued, price per share (in dollars per share) | $ / shares     $ 0.0357   $ 0.0357
2018 Equity Incentive Plan | Class A Common Stock          
Schedule Of Stockholders Equity [Line Items]          
Conversion of stock, shares issued (in shares)         292,534