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		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Basic earnings per share
Net income available to common stockholders	[1]	$ 27,964	$ 128,549	$ 76,848	$ 595,198
Basic weighted-average shares of common stock outstanding (in shares)		177,231	199,413	183,311	189,317
Basic earnings per share (in usd per share)		$ 0.16	$ 0.64	$ 0.42	$ 3.14
NEWMARK Group Inc Parent
Earnings Per Share
Reduction for dividends on preferred stock or units			$ 0		$ 6,200

[1] Includes a reduction for dividends on preferred stock or EPUs in the amount of $0.0 million and $6.2 million for the three and nine months ended September 30, 2021, respectively. (see Note 1 — “Organization and Basis of Presentation”).