Limited partnership units exchange ratio.

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- Definition

Share-based compensation arrangement by share-based payment award, number of shares registered.

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- Definition

Share based compensation arrangement by share based payment award units redeemed.

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- Definition

The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements. Represents currently earned compensation under cash arrangements (such as a profit-sharing plan, rabbi trust, and employee contract--excluding equity-based arrangements) that is not actually paid until a later date.

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- Definition

Amount of equity impact of cash distribution declared to unit-holder of limited partnership (LP).

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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- Definition

The number of limited partner units outstanding.

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- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

Net number of non-option equity instruments granted to participants.

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- Definition

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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- Definition

Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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- Definition

Number of shares issued under share-based payment arrangement.

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Compensation - Additional Information (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) shares	Mar. 31, 2019 USD ($) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 shares	Dec. 13, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future awards	377,200,000
Number of units redeemed (in shares)	291,721	88,545
Unrecognized compensation expense related to unvested RSUs \| $	$ 46,200
Deferred cash compensation expense recognized \| $	100	$ 200
Liability for deferred cash compensation awards \| $	$ 900		$ 900
Newmark Holdings, L.P.
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership units exchange ratio	0.4545
Newmark Holdings, L.P. \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership units outstanding (in shares)	5,926,780		4,683,571	219,887
Awards granted (in shares)	1,686,149		4,766,611
BGC Holdings, L.P.
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership units outstanding (in shares)	56,498,858		56,053,701	61,870,969
Awards granted (in shares)	884,335		319,586
Unrecognized compensation expense related to unvested RSUs \| $	$ 100
NEWMARK Group Inc Parent
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partners capital account units held by BGC (in shares)	16,138,694		17,097,639
Limited partnership units outstanding (in shares)	61,862,893		60,800,852	44,733,487
Number of units redeemed (in shares)	142,441	29,690
Awards granted (in shares)	1,650,749		13,813,204
NEWMARK Group Inc Parent \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income allocated to limited partnership units \| $	$ 549	$ 6,313
Maximum \| Newmark Holdings, L.P. \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	8 years
Maximum \| NEWMARK Group Inc Parent \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	7 years
Minimum \| Newmark Holdings, L.P. \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	2 years
Minimum \| NEWMARK Group Inc Parent \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership units exchange ratio	0.9461				1
Newmark Equity Plan \| Class A Common Stock \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized to be delivered pursuant to awards granted (in shares)					400,000,000.0
Shares registered to be delivered pursuant to awards granted (in shares)					65,000,000.0
Non Distribution Earning Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit granted during period (in shares)	4,900,000
Award vesting period	4 years
Executives And Non Executives Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partners capital account units held by BGC (in shares)	22,800,000