Quarterly report pursuant to Section 13 or 15(d)

Related-Party Transactions - Additional Information (Detail)

v3.21.2
Related-Party Transactions - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2020
Related Party Transaction [Line Items]          
Operating lease cost $ 6,512,000 $ 6,341,000 $ 13,101,000 $ 12,604,000  
Aggregate principal amount for employee notes receivable 125,000   125,000   $ 431,000
MMC [Member]          
Related Party Transaction [Line Items]          
Real estate brokerage commissions and financing fees from transactions with subsidiaries of Marcus & Millichap Company 337,000 880,000 794,000 1,600,000  
Commission expenses for transactions with subsidiaries of Marcus & Millichap Company 203,000 536,000 477,000 988,000  
Operating lease cost 332,000 332,000 $ 665,000 665,000  
Lease expiration date     May 31, 2022    
Accounts payable and other liabilities - related party 85,000   $ 85,000   $ 89,000
MMC [Member] | Transition Services Agreement [Member] | Selling, General and Administrative Expenses [Member]          
Related Party Transaction [Line Items]          
Selling, general and administrative expense $ (4,000) $ 16,000 $ 15,000 $ 42,000  
George M. Marcus [Member]          
Related Party Transaction [Line Items]          
Beneficial ownership percentage     38.00%