Exchangeable Partnership Units

No definition available.

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- Definition

Limited partnership units exchange ratio.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

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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.

+ References

No definition available.

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- Definition

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

+ References

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- Definition

The number of limited partner units outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
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-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187171-122770

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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.

+ References

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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.

+ References

No definition available.

+ Details

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

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

+ References

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

Number of shares issued under share-based payment arrangement.

+ References

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- Definition

Number of options vested.

+ References

No definition available.

+ Details

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Compensation - Additional Information (Detail)		3 Months Ended
Compensation - Additional Information (Detail)	Jan. 01, 2018	Mar. 31, 2021 USD ($) shares	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 shares	Dec. 13, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award
Shares available for future awards (in shares)		364,400,000
Number of shares vested and converted (in shares)		600,000
Unrecognized compensation expense related to unvested RSUs \| $		$ 78,000,000.0
Deferred cash compensation expense recognized \| $		35,000	$ 131,000
Liability for deferred cash compensation awards \| $		$ 0		$ 900,000
Executives And Non Executives Employees
Share-based Compensation Arrangement by Share-based Payment Award
Limited partners capital account units held by BGC (in shares)		35,600,000
Newmark Holdings, L.P.
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio (in percentage)		0.4545
Newmark Holdings, L.P. \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units outstanding (in shares)		10,032,936		10,646,797	4,683,571
BGC Holdings, L.P.
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units outstanding (in shares)		51,743,305		54,422,002	56,053,701
BGC Holdings, L.P. \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units outstanding (in shares)		8,400,000		9,100,000
Exchangeable partnership units (in shares)		3,700,000		4,500,000
NEWMARK Group Inc Parent
Share-based Compensation Arrangement by Share-based Payment Award
Limited partners capital account units held by BGC (in shares)		20,375,058		20,184,716
Limited partnership units outstanding (in shares)		64,132,911		66,626,185	60,800,852
NEWMARK Group Inc Parent \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units outstanding (in shares)		4,800,000		5,300,000
Exchangeable partnership units (in shares)		1,600,000		2,000,000.0
Maximum \| Newmark Holdings, L.P. \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period (in years)	8 years
Maximum \| NEWMARK Group Inc Parent \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period (in years)		7 years
Minimum \| Newmark Holdings, L.P. \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period (in years)	2 years
Minimum \| NEWMARK Group Inc Parent \| Limited Partnership Units
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period (in years)		3 years
Common Class A
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio (in percentage)						1
Common Class A \| NEWMARK Group Inc Parent
Share-based Compensation Arrangement by Share-based Payment Award
Limited partnership units exchange ratio (in percentage)		0.9365
Newmark Equity Plan \| Common Class A \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award
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
Award vesting period (in years)		4 years
Unit granted during period (in shares)		1,300,000