Related Party Transactions - Transactions with Executive Officers and Directors (Barry Gosin) (Details)						6 Months Ended
	Feb. 05, 2025 $ / shares shares	Jan. 13, 2025 $ / shares shares	Sep. 23, 2024 $ / shares shares	Aug. 07, 2024 USD ($) shares	Feb. 10, 2023 USD ($) tranche installment $ / shares shares	Jun. 30, 2025 USD ($) shares	Feb. 18, 2025	Dec. 31, 2024 shares	Oct. 23, 2024	Dec. 13, 2017
Related Party Transaction
Stock repurchased (in shares) | 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 A Common Stock
Related Party Transaction
Stock repurchased (in shares) | shares	1,309,367	186,732
Limited partnership units exchange ratio										1
APSUs
Related Party Transaction
Stock repurchased (in shares) | shares			123,336
PSUs
Related Party Transaction
Stock repurchased (in shares) | shares			611,167
SPUSs
Related Party Transaction
Stock repurchased (in shares) | shares			60,873
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
Annual cash bonus					$ 1,500,000
Exchangeable Newmark Holdings PSUs | Mr. Gosin
Related Party Transaction
Warrants and rights outstanding (in shares) | shares								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) | 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) | shares						1,238,620
Number of tranches | tranche					4
Class of warrant or right, advance award (in shares) | 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%
Number of installments | installment					3
Conversion percentage, tranche four					25.00%
Conversion percentage, tranche three					25.00%
Conversion percentage, tranche two					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