Annual report pursuant to Section 13 and 15(d)

Variable Interest Entity - Additional Information (Detail)

v3.22.2.2
Variable Interest Entity - Additional Information (Detail) - USD ($)
 12 Months Ended
Jun. 14, 2021
Sep. 30, 2022
Sep. 30, 2021
Sep. 30, 2020
Variable Interest Entity [Line Items]        
Goodwill   $ 41,093,000 $ 41,471,000 $ 37,754,000
Additional amount due to the seller upon FINRA's approval   1,000,000.0    
Purchase Agreement        
Variable Interest Entity [Line Items]        
Percentage of units acquired in exchange for other consideration 24.90%      
Initial payment to the seller $ 1,700,000      
Non-refundable deposit to the seller $ 4,200,000      
Percentage of remaining units deposited into escrow with the seller legal counsel 75.10%      
Additional amount paid to the seller upon FINRA's approval $ 1,000,000.0      
Amount already paid to the seller upon FINRA's approval $ 200,000      
Salomon Whitney LLC        
Variable Interest Entity [Line Items]        
Percentage of outstanding membership interests acquired 100.00%      
Payment to acquire business $ 7,000,000.0      
Goodwill $ 3,717,000 $ 3,700,000