Quarterly report pursuant to Section 13 or 15(d)

Related-Party Transactions - Additional Information (Detail)

v3.19.3
Related-Party Transactions - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Related Party Transaction [Line Items]          
Operating lease cost $ 6,148,000   $ 18,163,000    
Aggregate principal amount for employee notes receivable 523,000   523,000   $ 526,000
MMC [Member]          
Related Party Transaction [Line Items]          
Real estate brokerage commissions and financing fees from transactions with subsidiaries of Marcus & Millichap Company 1,200,000 $ 1,800,000 4,000,000.0 $ 4,900,000  
Commission expenses for transactions with subsidiaries of Marcus & Millichap Company 688,000 1,100,000 2,300,000 2,900,000  
Operating lease cost 333,000 257,000 $ 999,000 765,000  
Lease expiration date     May 31, 2022    
Accounts payable and other liabilities - related party 93,000   $ 93,000   $ 101,000
MMC [Member] | Transition Services Agreement [Member]          
Related Party Transaction [Line Items]          
Selling, general and administrative expense $ 21,000 $ 20,000 $ 96,000 $ 147,000  
George M. Marcus [Member]          
Related Party Transaction [Line Items]          
Beneficial ownership percentage     40.00%