Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 11, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Trading Symbol	NMRK
Entity Registrant Name	NEWMARK GROUP, INC.
Entity Central Index Key	0001690680
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Class A Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		138,921,532
Class B Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		15,840,049