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Notes Payable and Other Borrowings - Schedule of Notes Payable, Other and Short-term Borrowings (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Aug. 21, 2024	Jun. 10, 2024	Dec. 31, 2023	Oct. 19, 2023	Oct. 06, 2023	May 25, 2023	Jul. 10, 2020	Sep. 27, 2019
Debt Instrument [Line Items]
Total Notes payable and other borrowings	$ 1,440,706			$ 1,183,506
Deferred financing cost	8,400			6,500
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]
Stated interest rate	3.75%					3.75%
Senior notes	$ 255,526			254,814
BGC Partners 3.750% Senior Notes due October 1, 2024
Debt Instrument [Line Items]
Stated interest rate	3.75%								3.75%
Senior notes	$ 44,474			44,383
BGC Group 4.375% Senior Notes due December 15, 2025
Debt Instrument [Line Items]
Stated interest rate	4.375%				4.375%	4.375%
Senior notes	$ 287,279			286,729
BGC Partners 4.375% Senior Notes due December 15, 2025
Debt Instrument [Line Items]
Stated interest rate	4.375%							4.375%	4.375%
Senior notes	$ 11,818			11,800
BGC Group 8.000% Senior Notes due May 25, 2028
Debt Instrument [Line Items]
Stated interest rate	8.00%				8.00%	8.00%
Senior notes	$ 344,427			343,852
BGC Partners 8.000% Senior Notes due May 25, 2028
Debt Instrument [Line Items]
Stated interest rate	8.00%	8.00%					8.00%
Senior notes	$ 2,256			2,748
BGC Group 6.600% Senior Notes due June 10, 2029
Debt Instrument [Line Items]
Stated interest rate			6.60%
Senior notes	$ 494,926			$ 0
Total Notes payable and other borrowings			$ 495,000