Cover Page - shares	3 Months Ended
	Mar. 31, 2020	May 07, 2020
Document Information [Line Items]
Document Type	10-Q
Document Annual Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	001-38329
Entity Registrant Name	NEWMARK GROUP, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-4467492
Entity Address, Address Line One	125 Park Avenue
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10017
City Area Code	212
Local Phone Number	372-2000
Title of 12(b) Security	Class A Common Stock, $0.01 par value
Trading Symbol	NMRK
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001690680
Current Fiscal Year End Date	--12-31
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		156,940,608
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		21,285,533