Cover Page - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Feb. 24, 2021	Jun. 30, 2020
Document Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
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 Each Class	Class A Common Stock, $0.01 par value
Trading Symbol(s)	NMRK
Name of Each Exchange on Which Registered	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 733,860
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement for its 2021 annual meeting of stockholders are incorporated by reference in Part III of this Annual Report on Form 10-K
Amendment Flag	false
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Entity Central Index Key	0001690680
Common Class A
Document Information
Entity Common Stock, Shares Outstanding		162,086,746
Common Class B
Document Information
Entity Common Stock, Shares Outstanding		21,285,533