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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 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 shares authorized for issuance under share-based payment arrangement.

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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		12 Months Ended
Compensation - Narrative (Details)	Jun. 30, 2024 USD ($) shares	Jun. 30, 2023 USD ($) shares	Jun. 30, 2024 USD ($) shares	Jun. 30, 2023 USD ($) shares	Dec. 31, 2023 USD ($) shares	Dec. 13, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio	0.4545		0.4545
Unrecognized compensation expense \| $	$ 74,500,000		$ 74,500,000
Compensation expense (benefit) \| $	24,941,000	$ 19,487,000	$ 76,153,000	$ 54,894,000
Common stock, conversion for each restricted stock unit settled (in shares)			1
Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Compensation expense (benefit) \| $	$ 0	$ 0	$ 0	$ 0
Non Distribution Earning Units
Share-based Compensation Arrangement by Share-based Payment Award
Unit granted during period (in shares)	800,000	1,000,000.0	2,000,000	2,000,000
Number of shares vested and converted (in shares)	2,600,000	3,800,000	5,100,000	6,300,000
Newmark Holdings, L.P.
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio	0.4545		0.4545
NEWMARK Group Inc \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period			7 years
Shares purchased for award (in shares)			3,200,000
Fair value of non-vested \| $	$ 46,000,000.0		$ 46,000,000.0		$ 46,000,000.0
Unrecognized compensation expense \| $	$ 24,400,000		$ 24,400,000
Cost not yet recognized, period for recognition			1 year 6 months
NEWMARK Group Inc \| Non Distribution Earning Units \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Shares purchased for award (in shares)			2,300,000		2,300,000
Maximum \| NEWMARK Group Inc \| 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 Group Inc
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio	0.9248		0.9248
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)						400,000,000
Shares registered to be delivered pursuant to awards granted (in shares)	400,000,000		400,000,000
Shares purchased for award (in shares)			102,400,000
Shares available for future awards (in shares)	297,600,000		297,600,000