Marcus & Millichap, Inc. Quarterly report pursuant to Section 13 or 15(d)

Investments in Marketable Debt Securities, Available-for-Sale - Narrative (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($) security	Dec. 31, 2023
Marketable Securities [Line Items]
Weighted average contractual maturity	1 year 9 months 18 days	1 year 10 months 24 days
Fitch, AA Rating \| Moody's, Aaa Rating \| Standard & Poor's, AA Rating
Marketable Securities [Line Items]
Weighted average contractual maturity	1 year 9 months 18 days
Fitch, AA+ Rating \| Moody's, Aa3 Rating \| Standard & Poor's, AA+ Rating \| Weighted Average Credit AA Plus Rating
Marketable Securities [Line Items]
Available-for-sale, securities number of unrealized loss positions \| security	211
Available-for-sale, securities in unrealized loss positions, accumulated loss \| $	$ 2.7
Percentage of amortized cost	1.00%