Related Party Transactions - Transactions with Executive Officers and Directors (Barry Gosin) (Details)									3 Months Ended
	Feb. 05, 2025 $ / shares shares	Jan. 13, 2025 $ / shares shares	Sep. 23, 2024 $ / shares shares	Aug. 07, 2024 USD ($) shares	Dec. 31, 2023 shares	Apr. 01, 2023 shares	Mar. 30, 2023 USD ($) shares	Feb. 10, 2023 USD ($) tranche installment $ / shares shares	Mar. 31, 2025 USD ($) shares	Feb. 18, 2025	Dec. 31, 2024 shares	Oct. 23, 2024	Dec. 13, 2017
Related Party Transaction
Stock repurchased (in shares)			795,376
Preferred stock, redemption price per share (in dollars per share) | $ / shares			$ 14.19
Share price (in dollars per share) | $ / shares	$ 14.14	$ 11.93	$ 15.34
Limited partnership units exchange ratio			0.9248						0.4545	0.9279		0.9257
Class of warrant or right, exchange rate					14.29%
APSUs
Related Party Transaction
Stock repurchased (in shares)			123,336
PSUs
Related Party Transaction
Stock repurchased (in shares)			611,167
SPUSs
Related Party Transaction
Stock repurchased (in shares)			60,873
Class A Common Stock
Related Party Transaction
Stock repurchased (in shares)	1,309,367	186,732
Limited partnership units exchange ratio													1
Mr. Gosin
Related Party Transaction
Related party transaction, termination notice, period				6 months
Related party transaction, one time cash payment | $				$ 5,000,000
Related party transaction, annual compensation | $				17,500,000
Related party transaction, annual compensation, salary | $				1,000,000
Related party transaction, annual compensation, cash-based and share-based awards | $				$ 16,500,000
Class of warrant or right, conversion ratio					0.9231	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
Exchangeable Newmark Holdings PSUs | Mr. Gosin
Related Party Transaction
Warrants and rights outstanding (in shares)						176,804					354,076
Newmark Holdings NPSUs | Mr. Gosin
Related Party Transaction
Share price (in dollars per share) | $ / shares								$ 8.73
Number of conversion rights granted (in shares)				1,694,915					1,145,476
Conversion percentage								25.00%	25.00%
Class of warrant or right percentage									75.00%
Minimum gross revenue threshold | $								$ 10,000,000	$ 10,000,000
Class of warrant or right, rights exchanged (in shares)									1,238,620
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)								1,145,476
Related party transaction, upfront advance award, base for calculating number of grants in period | $								$ 10,000,000
Conversion percentage, tranche one								25.00%
Conversion percentage, tranche two								25.00%
Conversion percentage, tranche three								25.00%
Number of installments | installment								3
Conversion percentage, tranche four								25.00%
Newmark Holdings NPSUs | Mr. Gosin | Award Period One
Related Party Transaction
Share-based liabilities paid | $				$ 5,000,000
Newmark Holdings NPSUs | Mr. Gosin | Award Period Two
Related Party Transaction
Share-based liabilities paid | $				15,000,000
Newmark Holdings NPSUs | Mr. Gosin | Award Period Three
Related Party Transaction
Share-based liabilities paid | $				$ 1,500,000
Newmark Holdings PSU | Mr. Gosin
Related Party Transaction
Class of warrant or right, issued upon conversion (in shares)					1,240,901	1,237,644
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