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, 2022	Dec. 31, 2021	Dec. 31, 2020
Fully diluted earnings per share:
Net income available to common stockholders	[1]	$ 83,275	$ 744,528	$ 70,281
Allocations of net income to limited partnership interests in Newmark Holdings, net of tax		27,128	0	0
Net income for fully diluted shares		$ 110,403	$ 744,528	$ 70,281
Weighted-average shares:
Common stock outstanding (in shares)		180,337	190,179	179,106
Partnership units (units)		59,944	0	0
RSUs (Treasury stock method) (units)		3,255	4,310	355
Newmark exchange shares (in shares)		1,641	1,324	229
Fully diluted weighted-average shares of common stock outstanding (in shares)		245,177	195,813	179,690
Fully diluted earnings per share (in usd per share)		$ 0.45	$ 3.80	$ 0.39

[1] Includes a reduction for dividends on EPUs in the amount of $6.2 million and $9.8 million for the years ended December 31, 2021 and 2020, respectively (see Note 1 — “Organization and Basis of Presentation”).