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Limited partnership units exchange ratio.

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Share-Based Compensation Arrangement By Share-Based Payment Award, Shares Granted

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of additional shares authorized for issuance under share-based payment arrangement.

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Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Number of shares issued under share-based payment arrangement.

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Number of shares purchased for issuance under share-based payment arrangement.

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Intrinsic value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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Number of options vested.

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Compensation - Narrative (Details)		3 Months Ended		6 Months Ended
Compensation - Narrative (Details)	Oct. 18, 2024 shares	Jun. 30, 2025 USD ($) shares	Jun. 30, 2024 USD ($) shares	Jun. 30, 2025 USD ($) shares	Jun. 30, 2024 USD ($) shares	Feb. 18, 2025	Oct. 23, 2024	Oct. 17, 2024 shares	Sep. 23, 2024	Dec. 13, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio		0.4545		0.4545		0.9279	0.9257		0.9248
Unrecognized compensation expense \| $		$ 58,100,000		$ 58,100,000
Compensation expense (benefit) \| $		$ 0	$ 0	$ 0	$ 0
Common stock, conversion for each restricted stock unit settled (in shares)				1
Non Distribution Earning Units
Share-based Compensation Arrangement by Share-based Payment Award
Unit granted during period (in shares)		2,800,000	2,800,000	5,700,000	6,300,000
Number of shares vested and converted (in shares)		2,000,000.0	2,600,000	5,300,000	5,100,000
Newmark Holdings, L.P.
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio		0.4545		0.4545
Newmark Holdings Units
Share-based Compensation Arrangement by Share-based Payment Award
Compensation expense (benefit) \| $		$ 57,752,000	$ 24,941,000	$ 131,918,000	$ 76,153,000
Newmark Holdings Units \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period				7 years
Shares purchased for award (in shares)				5,700,000
Fair value of non-vested \| $		66,000,000.0		$ 66,000,000.0
Unrecognized compensation expense \| $		$ 20,500,000		$ 20,500,000
Cost not yet recognized, period for recognition				1 year 6 months
Newmark Holdings Units \| Non Distribution Earning Units \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Shares purchased for award (in shares)				1,700,000
Maximum \| Newmark Holdings Units \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period				7 years
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio										1
Class A Common Stock \| Newmark Holdings Units
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio		0.9273		0.9273
Newmark Equity Plan \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award
Shares authorized to be delivered pursuant to awards granted (in shares)								500,000,000		400,000,000
Additional share authorized (in shares)	100,000,000
Shares registered to be delivered pursuant to awards granted (in shares)		500,000,000		500,000,000
Shares purchased for award (in shares)				119,400,000
Shares available for future awards (in shares)		380,600,000		380,600,000