Compensation - Compensation Expense Related to Limited Partnership Units and Restricted Stock Units (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Share-based Compensation Arrangement by Share-based Payment Award
Issuance of common stock and exchangeability expenses	$ 36,953,000	$ 11,852,000	$ 89,232,000	$ 47,958,000
Total compensation expense	0	0	0	0
Equity-based compensation and allocations of net income to limited partnership units and FPUs			134,486,000	76,929,000
Newmark Holdings Units
Share-based Compensation Arrangement by Share-based Payment Award
Total compensation expense	57,752,000	24,941,000	131,918,000	76,153,000
Equity-based compensation and allocations of net income to limited partnership units and FPUs	60,141,000	25,486,000	134,487,000	76,929,000
Newmark Holdings Units | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units amortization	14,017,000	5,920,000	26,365,000	13,679,000
Newmark Holdings Units | Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Issuance of common stock and exchangeability expenses	36,953,000	11,852,000	89,232,000	47,958,000
Limited partnership units amortization	6,782,000	7,169,000	16,321,000	14,516,000
Allocations of net income to limited partnership units and FPUs	$ 2,389,000	$ 545,000	$ 2,569,000	$ 776,000