The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI https://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

Name:	us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
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

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_CounterpartyNameAxis=nmrk_CFS11Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=nmrk_Spring11Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=nmrk_EquityPurchaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=nmrk_NewmarkS11LPLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=nmrk_NewmarkS11Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Related Party Transactions - Acquisition of Spring11 Ownership Interest from Cantor (Details) - USD ($)	1 Months Ended	12 Months Ended
	Feb. 28, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction
Fees to related parties		$ 28,502,000	$ 23,789,000	$ 22,573,000
CFS11 \| Spring 11 \| Equity Purchase Agreement \| Subsequent Event
Related Party Transaction
Fees to related parties	$ 11,530,598
CFS11 \| Spring 11 \| Equity Purchase Agreement \| Subsequent Event \| Newmark S11 LP LLC
Related Party Transaction
Equity method investment ownership percentage	33.78%
CFS11 \| Spring 11 \| Equity Purchase Agreement \| Newmark S11 \| Subsequent Event \| Newmark S11 LP LLC
Related Party Transaction
Equity method investment ownership percentage	100.00%