Earnings Per Share and Weighted-Average Shares Outstanding - Calculation of Fully Diluted 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
Fully diluted earnings per share:
Net income available to common stockholders	[1]	$ 42,575	$ 83,275	$ 744,528
Allocations of net income to limited partnership interests in Newmark Holdings, net of tax		0	27,128	0
Net income for fully diluted shares		$ 42,575	$ 110,403	$ 744,528
Weighted-average shares:
Common stock outstanding (in shares)		173,475	180,337	190,179
Partnership units (units)		0	59,944	0
RSUs (Treasury stock method) (units)		2,413	3,255	4,310
Newmark exchange shares (in shares)		494	1,641	1,324
Fully diluted weighted-average shares of common stock outstanding (in shares)		176,382	245,177	195,813
Fully diluted earnings per share (in usd per share)		$ 0.24	$ 0.45	$ 3.80

[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”).