Earnings Per Share and Weighted-Average Shares Outstanding - Calculation of Basic Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Basic earnings per share
Net income available to common stockholders	[1]	$ 42,575	$ 83,275	$ 744,528
Basic weighted-average shares of common stock outstanding (in shares)		173,475	180,337	190,179
Basic earnings per share (in usd per share)		$ 0.25	$ 0.46	$ 3.91
NEWMARK Group Inc Parent
Basic earnings per share
Reduction for dividends on preferred stock or units				$ 6,200

[1] Includes a reduction for dividends on EPUs in the amount of $6.2 million for the year ended December 31, 2021(see Note 1 — “Organization and Basis of Presentation”).