Related Party Transactions - Transactions with Executive Officers and Directors (Barry Gosin) (Details)	Dec. 31, 2023 shares	Apr. 01, 2023 shares	Mar. 30, 2023 USD ($) shares	Feb. 10, 2023 USD ($) tranche installment $ / shares shares
Related Party Transaction
Class of warrant or right, exchange rate	14.29%
Mr. Gosin
Related Party Transaction
Class of warrant or right, conversion ratio		0.9252
Annual cash bonus | $				$ 1,500,000
Mr. Gosin | Class A Common Stock
Related Party Transaction
Issuance of Class A common stock for Newmark RSUs (in shares)			189,024
Class of warrant or right, redeemed | $			$ 3,125,001
Newmark Holdings NPSUs | Mr. Gosin
Related Party Transaction
Class of warrant or right, rights converted (in shares)	1,145,494	1,145,494
Number of tranches | tranche				4
Class of warrant or right, advance award (in shares)				1,145,475
Related party transaction, upfront advance award, base for calculating number of grants in period | $				$ 10,000,000
Share price (in dollars per share) | $ / shares				$ 8.73
Conversion percentage				25.00%
Number of installments | installment				3
Conversion percentage, tranche one				25.00%
Conversion percentage, tranche two				25.00%
Conversion percentage, tranche three				25.00%
Conversion percentage, tranche four				25.00%
Minimum gross revenue threshold | $				$ 10,000,000
Newmark Holdings PSU | Mr. Gosin
Related Party Transaction
Class of warrant or right, issued upon conversion (in shares)	1,240,901	1,237,644
PSU conversion ratio	0.9231
Exchangeable Newmark Holdings PSUs | Mr. Gosin
Related Party Transaction
Warrants and rights outstanding (in shares)		176,804
Non-Exchangeable Newmark Holdings PSUs | Mr. Gosin
Related Party Transaction
Class of warrant or right, conversion ratio			0.9303
Class of warrant or right, rights exercised (in shares)			203,186