Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Revenues		$ 357,908	$ 319,340	$ 979,307	$ 859,908
Type of Revenue [Extensible List]		nmrk:CommissionsMember	nmrk:CommissionsMember	nmrk:CommissionsMember	nmrk:CommissionsMember
Gains from mortgage banking activities/originations, net		$ 72,332	$ 51,972	$ 148,769	$ 132,763
Management services, servicing fees and other		156,394	147,497	457,692	423,217
Revenues		586,634	518,809	1,585,768	1,415,888
Expenses:
Compensation and employee benefits		341,036	291,382	921,126	819,109
Equity-based compensation and allocations of net income to limited partnership units and FPUs		56,647	40,776	109,871	125,559
Total compensation and employee benefits		397,683	332,158	1,030,997	944,668
Operating, administrative and other		86,297	84,914	275,939	240,389
Fees to related parties		7,088	6,644	21,035	19,839
Depreciation and amortization		36,781	25,873	98,510	68,587
Total operating expenses		527,849	449,589	1,426,481	1,273,483
Other income, net		108,711	93,717	95,267	99,059
Income from operations		167,496	162,937	254,554	241,464
Interest expense, net		(8,167)	(11,509)	(23,947)	(35,500)
Income before income taxes and noncontrolling interests		159,329	151,428	230,607	205,964
Provision for income taxes		36,760	35,870	52,568	53,625
Consolidated net income		122,569	115,558	178,039	152,339
Less: Net income attributable to noncontrolling interests		33,871	47,321	49,769	63,366
Net income available to common stockholders		88,698	68,237	128,270	88,973
Basic earnings per share
Net income available to common stockholders	[1]	$ 85,475	$ 66,563	$ 118,599	$ 87,107
Basic earnings per share		$ 0.48	$ 0.43	$ 0.67	$ 0.56
Basic weighted-average shares of common stock outstanding		177,020	155,152	178,122	155,348
Fully diluted earnings per share
Net income for fully diluted shares		$ 99,500	$ 80,038	$ 122,379	$ 104,580
Fully diluted earnings per share		$ 0.48	$ 0.43	$ 0.66	$ 0.56
Fully diluted weighted-average shares of common stock outstanding		206,616	185,134	185,413	185,559

[1] Includes a reduction for dividends on preferred stock or units in the amount of $3.2 million and $1.7 million for the three months ended September 30, 2019 and 2018, respectively, and $9.7 million and $1.9 million for the nine months ended September 30, 2019 and 2018, respectively.