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Amount for accounts payable to related parties.

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Area of a real estate property.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Balance held at close of period in number of shares.

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Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

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The cash inflow from the capital received in cash from a partner in a partnership during the period.

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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 new stock issued during the period.

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Related Party Transactions - Other Related Party Transactions and Cantor Rights to Purchase Cantor Units from Newmark Holdings (Details)							1 Months Ended		12 Months Ended
	Oct. 25, 2022 USD ($) shares	May 17, 2022 USD ($) shares	Oct. 28, 2021 USD ($) shares	Jun. 28, 2021 USD ($)	Mar. 31, 2021 USD ($) shares	Nov. 30, 2018 USD ($)	Jan. 31, 2022 USD ($) ft²	May 31, 2021 USD ($)	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jul. 31, 2022	Jul. 02, 2021 shares	Nov. 30, 2020 shares	May 15, 2020 ft²	Dec. 02, 2019 shares	Nov. 06, 2018	Dec. 13, 2017
Related Party Transaction
Accounts receivable, related parties									$ 0	$ 8,262,000
Payables to related parties									9,745,000	10,762,000
Operating lease payments									$ 106,800,000	81,700,000	$ 49,000,000
Limited partnership units exchange ratio									0.4545
Proceeds from sales of partnership interest									$ 0	6,898,000	$ 0
Shares owned (in shares) \| shares													5,278,011	250,742		93,562
Maximum
Related Party Transaction
Remaining lease terms									11 years
Options to extend leases									10 years
Knotel, Inc.
Related Party Transaction
Due from related party, percentage from sale									10.00%
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 Group Inc Parent
Related Party Transaction
Limited partnership units exchange ratio									0.9303
Cantor \| Founding partner interest
Related Party Transaction
Stock issued (in shares) \| shares	104,701	184,714	299,910		273,088
Proceeds from sales of partnership interest	$ 446,647	$ 763,064	$ 975,064		$ 1,105,598
Cantor \| Founding partner interest \| Newmark Holdings
Related Party Transaction
Shares owned (in shares) \| shares									150,842
Cantor \| Limited partner interest
Related Party Transaction
Stock issued (in shares) \| shares	102,454	23,562	523,284		735,625
Proceeds from sales of partnership interest	$ 272,100	$ 100,079	$ 1,898,363		$ 2,918,919
Affiliated Persons or Entities \| RKF Retail Holdings LLC \| Sublease Agreeement
Related Party Transaction
Remaining lease terms							6 months								1 year
Area of real estate property \| ft²							21,000								21,000
Options to extend leases												1 year
Affiliated Persons or Entities \| Cantor
Related Party Transaction
Monthly payment on sublease							$ 81,600
Operating lease payments									$ 1,000,000
Affiliated Persons or Entities \| BGC Holdings, L.P.
Related Party Transaction
Accounts receivable, related parties								$ 1,100,000
Monthly payment on sublease								$ 15,000
Operating lease payments										$ 500,000
Employee of chairman
Related Party Transaction
Annual base salary				$ 125,000
Employee of chairman \| Maximum
Related Party Transaction
Annual discretionary bonus rate				30.00%
Employee
Related Party Transaction
Travel and housing reimbursement				$ 250,000
Cantor Credit Agreement \| Cantor
Related Party Transaction
Maximum revolving credit						$ 250,000,000
Basis spread on variable rate						1.00%