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

No definition available.

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

- Definition

The maximum amount of borrowing capacity under a line of credit that is available as of the balance sheet date for a specific purpose other than for financing goods acquired for inventory or imminent delivery to a customer.

+ References

No definition available.

+ Details

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

- Definition

Amount of increase (decrease) of the credit facility.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

+ Details

Name:	us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_SecuritiesFinancingTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying value as of the balance sheet date of the outstanding short-term borrowings under a revolving line of credit used by mortgage bankers to finance the origination or purchase of loans.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

+ Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=nmrk_CommittedLinesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=nmrk_UncommittedLinesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nmrk_WarehouseFacilityDueMayFiveTwoThousandTwentySixMember
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:	us-gaap_DebtInstrumentAxis=nmrk_WarehouseFacilityDueSeptemberTwentyFiveTwoThousandTwentySixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nmrk_WarehouseFacilityDueOctoberFourTwoThousandTwentySixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nmrk_FannieMaeRepurchaseAgreementOpenMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Warehouse Facilities Collateralized by U.S. Government Sponsored Enterprises (Details) - USD ($)				3 Months Ended
	May 05, 2026	Jan. 30, 2026	Dec. 01, 2025	Mar. 31, 2026	Dec. 31, 2025
Securities Financing Transaction
Outstanding draws				$ 1,124,651,000	$ 892,439,000
Committed Lines
Securities Financing Transaction
Lines available				1,450,000,000
Uncommitted Lines
Securities Financing Transaction
Lines available				1,600,000,000
Warehouse facility due May 5, 2026
Securities Financing Transaction
Outstanding draws				$ 240,934,000	129,645,000
Basis spread on variable rate				1.30%
Warehouse facility due May 5, 2026 \| Subsequent Event
Securities Financing Transaction
Basis spread on variable rate	1.20%
Warehouse facility due May 5, 2026 \| Committed Lines
Securities Financing Transaction
Lines available				$ 450,000,000
Warehouse facility due May 5, 2026 \| Uncommitted Lines
Securities Financing Transaction
Lines available				300,000,000
Warehouse facility due September 25, 2026
Securities Financing Transaction
Outstanding draws				$ 287,984,000	232,356,000
Basis spread on variable rate				1.30%
Warehouse facility due September 25, 2026 \| Committed Lines
Securities Financing Transaction
Lines available				$ 200,000,000
Warehouse facility due September 25, 2026 \| Uncommitted Lines
Securities Financing Transaction
Lines available				200,000,000
Warehouse facility due October 3, 2026
Securities Financing Transaction
Outstanding draws				$ 533,710,000	334,642,000
Basis spread on variable rate		1.20%		1.20%
Warehouse facility due October 3, 2026 \| Committed Lines
Securities Financing Transaction
Lines available				$ 800,000,000
Warehouse line was temporarily increased			$ 400,000,000.0
Warehouse facility due October 3, 2026 \| Uncommitted Lines
Securities Financing Transaction
Lines available				600,000,000
Fannie Mae repurchase agreement, open maturity
Securities Financing Transaction
Outstanding draws				$ 62,023,000	$ 195,796,000
Basis spread on variable rate				1.15%
Fannie Mae repurchase agreement, open maturity \| Committed Lines
Securities Financing Transaction
Lines available				$ 0
Fannie Mae repurchase agreement, open maturity \| Uncommitted Lines
Securities Financing Transaction
Lines available				$ 500,000,000