Lessor, Operating Sublease, Lease Payment

No definition available.

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Balance Type:	credit
Period Type:	duration

- Definition

Related Party Transaction, Due from (to) Related Party, Percentage From Sale

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Related Party Transaction, Employee Compensation, Annual Compensation

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Related Party Transaction Limit On Loan Not Yet Acquired Or Sold

+ References

No definition available.

+ Details

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Namespace Prefix:	nmrk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Related Party Transaction Limit On Loan Outstanding

+ References

No definition available.

+ Details

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Namespace Prefix:	nmrk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Related Party Transaction Maximum Amount Per Loan

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

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-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section S99
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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479773/842-30-50-3

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Net rentable area for properties owned.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of operating lease income from lease payments paid and payable to lessor. Excludes variable lease payments not included in measurement of lease receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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-Subparagraph (SX 210.6-03(i)(1))
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
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Period Type:	duration

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Related Party Transactions - Other Related Party Transactions (Details) ft² in Thousands			1 Months Ended		3 Months Ended	6 Months Ended		12 Months Ended
	Dec. 20, 2023 USD ($)	Nov. 30, 2018 USD ($)	Jan. 31, 2022 USD ($) ft²	Feb. 28, 2019 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Jan. 12, 2024	Mar. 10, 2022 USD ($)	Mar. 16, 2020 USD ($)	Feb. 26, 2020 USD ($)	Nov. 28, 2018 USD ($)
Related Party Transaction
Maximum amount per loan				$ 100,000,000
Limit on loans that have not yet been acquired or sold				250,000,000
Limit on loans outstanding				$ 250,000,000
Long-term debt						$ 745,161,000		$ 547,260,000
Due from related party, percentage from sale						10.00%
Annual compensation								400,000
Unsecured Debt \| $7.500% Senior Notes
Related Party Transaction
Stated interest rate									7.50%
Revolving Credit Facility \| Line of Credit
Related Party Transaction
Maximum revolving credit										$ 600,000,000	$ 465,000,000.0	$ 425,000,000.0	$ 250,000,000.0
Revolving Credit Facility \| Line of Credit \| Cantor Credit Agreement
Related Party Transaction
Maximum revolving credit	$ 150,000,000	$ 250,000,000
Basis spread on variable rate		1.00%
Borrowings of long-term debt	130,000,000					$ 130,000,000
Long-term debt						0		130,000,000.0
Related Party
Related Party Transaction
Payables to related parties						6,700,000		$ 6,600,000
Operating lease, lease income, lease payments					$ 200,000		$ 500,000
Related Party \| Cantor
Related Party Transaction
Lease, term of contract (in years)			6 months
Net rentable area \| ft²			21
Monthly payment on sublease			$ 81,600
Lessor, operating lease, renewal term					3 months		3 months
Related Party \| Unsecured Debt \| $7.500% Senior Notes
Related Party Transaction
Stated interest rate									7.50%
Related Party \| Cantor Credit Agreement \| Line of Credit
Related Party Transaction
Maximum revolving credit		$ 250,000,000
Basis spread on variable rate		1.00%
Related Party \| Revolving Credit Facility \| Line of Credit \| Cantor Credit Agreement
Related Party Transaction
Borrowings of long-term debt	$ 130,000,000
Long-term debt						$ 0