Related Party Transactions - Cantor Rights to Purchase Cantor Units from Newmark Holdings (Details)	Feb. 18, 2025 shares	Oct. 23, 2024 USD ($) shares	Jun. 30, 2025 USD ($) shares	Dec. 31, 2024 USD ($)	Sep. 23, 2024	Nov. 06, 2018	Dec. 13, 2017
Related Party Transaction
Limited partnership units exchange ratio	0.9279	0.9257	0.4545		0.9248
Receivable related to tax receivable agreement			$ 20,600,000
Payable related to tax receivable agreement			$ 17,511,000	$ 0
Related Party
Related Party Transaction
Tax receivable agreement, cash savings, percentage			85.00%
Receivable related to tax receivable agreement			$ 20,600,000
Payable related to tax receivable agreement			$ 17,500,000
General partners' capital account, units outstanding (in shares) | shares			397,631
Founding partner interest | Related Party
Related Party Transaction
Issuance of Class A common stock for Newmark RSUs (in shares) | shares		500,617
Proceeds from the sale of limited partnership interests		$ 1,824,045
Founding partner interest | Related Party | Exchangeable Limited Partnership Interests
Related Party Transaction
Unit exercised during period (in shares) | shares	7,782,387	13,861
Unit granted during period (in shares) | shares	7,221,277	12,831
Limited partner interest | Related Party
Related Party Transaction
Issuance of Class A common stock for Newmark RSUs (in shares) | shares		162,086
Proceeds from the sale of limited partnership interests		$ 506,022
Common Stock
Related Party Transaction
Limited partnership units exchange ratio						1
Class A Common Stock
Related Party Transaction
Limited partnership units exchange ratio							1
Class A Common Stock | Newmark Holdings Units
Related Party Transaction
Limited partnership units exchange ratio			0.9273