Earnings Per Share and Weighted-Average Shares Outstanding - Schedule of Fully Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Fully diluted earnings per share:
Net income (loss) available to common stockholders	$ 14,419	$ (8,766)
Allocations of net income to limited partnership interests in Newmark Holdings, net of tax	5,191	0
Net income (loss) for fully diluted shares	$ 19,610	$ (8,766)
Weighted-average shares:
Common stock outstanding (in shares)	182,646	176,352
Partnership units (in shares)	68,104	0
RSUs (Treasury stock method) (in shares)	4,886	0
Newmark exchange shares (in shares)	405	0
Fully diluted weighted-average shares of common stock outstanding (in shares)	256,041	176,352
Fully diluted earnings per share (in dollars per share)	$ 0.08	$ (0.05)