Annual report pursuant to Section 13 and 15(d)

Related-Party Transactions - Additional Information (Detail)

v3.19.3.a.u2
Related-Party Transactions - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Related Party Transaction [Line Items]      
Operating lease cost $ 24,372,000    
Aggregate principal amount for employee notes receivable 388,000 $ 526,000  
MMC [Member]      
Related Party Transaction [Line Items]      
Real estate brokerage commissions and financing fees from transactions with subsidiaries of Marcus & Millichap Company 5,200,000 7,700,000 $ 2,100,000
Commission expenses for transactions with subsidiaries of Marcus & Millichap Company 3,000,000.0 4,600,000 1,200,000
Operating lease cost $ 1,300,000 1,000,000.0 1,000,000.0
Lease expiration date May 31, 2022    
Accounts payable and other liabilities - related party $ 88,000 101,000  
MMC [Member] | Transition Services Agreement [Member]      
Related Party Transaction [Line Items]      
Selling, general and administrative expense $ 127,000 $ 197,000 $ 210,000
George M. Marcus [Member]      
Related Party Transaction [Line Items]      
Beneficial ownership percentage 40.00%