Compensation - Compensation Expense Related to Limited Partnership Units and Restricted Stock Units (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award
Issuance of common stock and exchangeability expenses	$ 30,059,000	$ 15,056,000	$ 78,017,000	$ 42,762,000
Total compensation expense	43,523,000	26,472,000	119,675,000	81,366,000
Equity-based compensation and allocations of net income to limited partnership units and FPUs			125,678,000	84,805,000
Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Total compensation expense	0	0	0	0
Newmark Holdings Units
Share-based Compensation Arrangement by Share-based Payment Award
Equity-based compensation and allocations of net income to limited partnership units and FPUs	48,749,000	29,548,000	125,678,000	84,805,000
Newmark Holdings Units | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units amortization	4,994,000	5,819,000	18,672,000	18,003,000
Newmark Holdings Units | Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Issuance of common stock and exchangeability expenses	30,059,000	15,056,000	78,017,000	42,762,000
Limited partnership units amortization	8,470,000	5,597,000	22,986,000	20,601,000
Allocations of net income to limited partnership units and FPUs	$ 5,226,000	$ 3,076,000	$ 6,003,000	$ 3,439,000