Estimated fair value of deferred compensation awards.

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Estimated fair value of limited partnership units held by executives and non-executive employees, awarded in lieu of cash compensation for salaries, commissions and/or discretionary or guaranteed bonuses.

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Estimated Fair Value Of Restricted Stock Units

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Limited Partnership Interest, Conversion Ratio

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Limited Partnership Interests Exchange Ratio

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Notional value of limited partnership units with post termination pay out amount.

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Number Of Common Stock Settled Per Restricted Stock Unit

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Number of limited partnership units exchangeable into shares.

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Share based compensation arrangement by share based payment award equity instruments other than options granted in period fair value.

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Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Fair Value

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Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vesting Date Fair Value

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Share-based Compensation Arrangement by Share-based Payment Award, Number Of Restricted Stock Award Settled Per Common Stock

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Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation Per Share

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Period over which the sale or transferability of an the equity-based payment award is restricted, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Restricted shares that were previously issued and then had their restriction released during the period.

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Value of shares withheld for tax, related to share-based compensation.

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Amount of decrease to equity for grantee's tax withholding obligation for award under share-based payment arrangement.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Number of shares issued for each share of convertible preferred stock that is converted.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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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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Amount of additional cost recognized for award under share-based payment arrangement from occurrence of event accelerating recognition of cost.

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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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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Compensation - Narrative (Details) $ / shares in Units, $ in Thousands				3 Months Ended		12 Months Ended
	Feb. 05, 2025 $ / shares shares	Jul. 01, 2023 USD ($) shares	Jun. 30, 2023 USD ($)	Mar. 31, 2026 USD ($) shares	Mar. 31, 2025 USD ($) shares	Dec. 31, 2025 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares grant of future awards (in shares)				398,600,000
Number of common stock settled per restricted stock unit (in shares)				1
Accelerated vesting of restricted stock (in shares)	1,300,000
Shares withheld to satisfy tax liabilities (in shares)					700,000
Tax withholding (in dollars per share) \| $ / shares	$ 9.38
Accelerated vesting expense \| $					$ 9,000
Estimated fair value of restricted stock units \| $				$ 12,600		$ 15,700
Estimated fair value of the deferred compensation awards \| $				$ 0		$ 0
Number of shares released the restrictions (in shares)				0	0
Number of restricted stock award settled per common stock (in shares)				1
Newmark Holdings
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership interest, conversion ratio				1
Restricted Stock, Dividend Eligible
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership units outstanding (in shares)				21,000,000.0		21,600,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, decrease for tax withholding obligation \| $		$ 74,000
Limited partnership units outstanding (in shares)				75,874,000		77,643,000
Unrecognized compensation expense related to unvested \| $				$ 146,700	$ 226,600
Unrecognized compensation expense related to unvested recognized period (in years)				4 years 8 months 23 days	4 years 9 months
Total vesting-date fair value of RSUs \| $				$ 52,500	$ 66,400
Granted \| $				$ 31,222
Weighted-average remaining contractual term (years)				4 years 8 months 23 days		3 years 10 months 2 days
Granted (in shares)				3,909,000
Restricted Stock Units, Tax Account
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to unvested \| $				$ 26,500	65,400
Granted \| $			$ 123,200
Vested \| $				$ 4,300	$ 4,800
Weighted-average remaining contractual term (years)				7 years	7 years 9 months 7 days
Share-based payment arrangement, expense \| $				$ 4,300	$ 4,300
Restricted Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership units outstanding (in shares)				300,000		306,000
Unrecognized compensation expense related to unvested \| $				$ 500
Total vesting-date fair value of RSUs \| $				100	26,900
Granted \| $				$ 0
Weighted-average remaining contractual term (years)				6 years 3 months 14 days		6 years 4 months 13 days
Share-based payment arrangement, expense \| $				$ 0	$ 4,200
Shares withheld to satisfy tax liabilities (in shares)				0	700,000
Granted (in shares)		38,600,000		0
Restricted Shares \| BGC or Newmark
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, forfeited (in shares)				0	0
Restricted BGC Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership units outstanding (in shares)				0		0
Restricted BGC Stock \| Newmark
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership units outstanding (in shares)				0		0
Restricted Newmark Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares released the restrictions (in shares)				0	0
Restricted Stock, Dividend Eligible
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership units outstanding (in shares)				300,000
Minimum \| Restricted Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares saleable period (in years)				5 years
Maximum \| Restricted Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares saleable period (in years)				10 years
LPUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Limited partnership interests exchange ratio				0.9270
LPUs \| REUs \| BGC Holdings
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding (in shares)				100,000		100,000
LPUs \| REUs \| Newmark
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Notional value with post-termination pay-out amount \| $				$ 500		$ 500
Aggregate estimated fair value of limited partnership units \| $				$ 200		$ 200
LPUs \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares, restriction period (in years)				2 years
LPUs \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares, restriction period (in years)				5 years
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-equivalent limited partnership units exchangeable into shares (in shares)				100,000		100,000
Stock issued to employees (in shares)				2,100,000	1,800,000
Share-based payment arrangement, decrease for tax withholding obligation \| $				$ 9,800	$ 8,500
Accelerated vesting of restricted stock (in shares)	600,000
Conversion right (in shares)	1
Shares withheld to satisfy tax liabilities (in shares)	700,000
Shares, forfeited (in shares)				24,088	270,652
Class A Common Stock \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of shares withheld \| $				$ 16,100	$ 19,500
Equity plan \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized to be delivered pursuant to awards granted (in shares)		600,000,000.0