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Notes Payable and Other Borrowings - Summary Notes Payable, Other and Short-term Borrowings (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Oct. 06, 2023	May 25, 2023	Jul. 10, 2020	Sep. 27, 2019
Debt Instrument [Line Items]
Total Notes payable and other borrowings	$ 944,961	$ 1,183,506
Senior Revolving Credit Facility \| Unsecured Debt
Debt Instrument [Line Items]
Unsecured senior revolving credit agreement	0	239,180
BGC Group 3.750% Senior Notes due October 1, 2024
Debt Instrument [Line Items]
Senior notes	$ 255,056	254,814
Stated interest rate	3.75%		3.75%
BGC Partners 3.750% Senior Notes due October 1, 2024
Debt Instrument [Line Items]
Senior notes	$ 44,410	44,383
Stated interest rate	3.75%					3.75%
BGC Group 4.375% Senior Notes due December 15, 2025
Debt Instrument [Line Items]
Senior notes	$ 286,908	286,729
Stated interest rate	4.375%		4.375%
BGC Partners 4.375% Senior Notes due December 15, 2025
Debt Instrument [Line Items]
Senior notes	$ 11,802	11,800
Stated interest rate	4.375%				4.375%	4.375%
BGC Group 8.000% Senior Notes due May 25, 2028
Debt Instrument [Line Items]
Senior notes	$ 344,039	343,852
Stated interest rate	8.00%		8.00%
BGC Partners 8.000% Senior Notes due May 25, 2028
Debt Instrument [Line Items]
Senior notes	$ 2,746	$ 2,748
Stated interest rate	8.00%			8.00%