Quarterly report pursuant to Section 13 or 15(d)

Related-Party Transactions - Additional Information (Detail)

v3.21.1
Related-Party Transactions - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2020
Related Party Transaction [Line Items]      
Operating lease cost $ 6,589,000 $ 6,263,000  
Aggregate principal amount for employee notes receivable 178,000   $ 431,000
MMC [Member]      
Related Party Transaction [Line Items]      
Real estate brokerage commissions and financing fees from transactions with subsidiaries of Marcus & Millichap Company 457,000 766,000  
Commission expenses for transactions with subsidiaries of Marcus & Millichap Company 274,000 453,000  
Operating lease cost $ 333,000 333,000  
Lease expiration date May 31, 2022    
Accounts payable and other liabilities - related party $ 93,000   $ 89,000
MMC [Member] | Transition Services Agreement [Member]      
Related Party Transaction [Line Items]      
Selling, general and administrative expense $ 19,000 $ 26,000  
George M. Marcus [Member]      
Related Party Transaction [Line Items]      
Beneficial ownership percentage 39.00%