Earnings Per Share and Weighted-Average Shares Outstanding - Calculation of Basic Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Basic earnings per share
Net income available to common stockholders	[1]	$ 362	$ 31,464
Basic weighted-average shares of common stock outstanding (in shares)		188,881	183,254
Basic earnings per share (in usd per share)		$ 0.00	$ 0.17
NEWMARK Group Inc Parent
Earnings Per Share
Reduction for dividends on preferred stock or units			$ 1,600

[1] Includes a reduction for dividends on preferred stock or EPUs in the amount $1.6 million for the three months ended March 31, 2021. (see Note 1 — “Organization and Basis of Presentation”).