Marcus & Millichap, Inc. Annual report pursuant to Section 13 and 15(d)

Investments in Marketable Debt Securities, Available-for-Sale - Narrative (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Weighted average contractual maturity	1 year 1 month 6 days	1 year 6 months
Fitch, AA Rating \| Moody's, Aaa Rating \| Standard & Poor's, AA Rating
Schedule of Available-for-sale Securities [Line Items]
Weighted average contractual maturity	1 year 1 month 28 days
Fitch, AA+ Rating \| Moody's, Aa3 Rating \| Standard & Poor's, AA+ Rating \| Weighted Average Credit AA Plus Rating
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, securities number of unrealized loss positions	224
Available-for-sale, securities in unrealized loss positions, accumulated loss	$ (5,500)
Percentage of amortized cost	1.68%