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		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Basic earnings per share
Net income available to common stockholders	[1]	$ 48,519	$ 435,178	$ 48,881	$ 466,642
Basic weighted-average shares of common stock outstanding (in shares)		183,948	185,114	186,401	184,190
Basic earnings per share (in usd per share)		$ 0.26	$ 2.35	$ 0.26	$ 2.53
NEWMARK Group Inc Parent
Earnings Per Share
Reduction for dividends on preferred stock or units			$ 4,600		$ 6,200

[1] Includes a reduction for dividends on preferred stock or EPUs in the amount of $4.6 million and $6.2 million for the three and six months ended June 30, 2021, respectively. (see Note 1 — “Organization and Basis of Presentation”).