Schedule I - Parent Company Only - Long Term Debt - Additional Information (Detail) - USD ($)					12 Months Ended
	Mar. 12, 2024	Mar. 08, 2024	Sep. 27, 2019	Jul. 24, 2018	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 06, 2024	Jun. 07, 2024	Apr. 26, 2024	Oct. 07, 2023	Oct. 06, 2023	Mar. 10, 2022	Jul. 10, 2020	Nov. 28, 2018	Aug. 06, 2018	Mar. 19, 2018
Debt Instrument [Line Items]
Stated interest rate												8.00%
Long-term debt					$ 1,141,709,000	$ 944,326,000
Deferred financing costs					12,000,000	6,500,000
Total					$ 257,435,000
Redemption price as percentage of principal amount (as a percent)			101.00%
BGC Partners 5.375% Senior Notes due July 24, 2023
Debt Instrument [Line Items]
Stated interest rate				5.375%
Debt issuance costs				$ 5,800,000
Total						14,500,000	$ 25,500,000
Principal amount of debt component				$ 450,000,000.0
Redemption price as percentage of principal amount (as a percent)				101.00%
Carrying amount of debt component				$ 444,200,000
BGC Partners 5.375% Senior Notes due July 24, 2023 | Parent Company
Debt Instrument [Line Items]
Stated interest rate				5.375%
BGC Partners 3.750% Senior Notes due October 1, 2024
Debt Instrument [Line Items]
Stated interest rate			3.75%		3.75%
Long-term debt					$ 0	44,383,000
Debt issuance costs			$ 3,900,000
Total					$ 1,300,000	9,500,000	12,100,000
Principal amount of debt component			300,000,000.0
Carrying amount of debt component			$ 296,100,000
BGC Partners 3.750% Senior Notes due October 1, 2024 | Senior Notes
Debt Instrument [Line Items]
Long-term debt												$ 255,500,000
BGC Partners 3.750% Senior Notes due October 1, 2024 | Parent Company
Debt Instrument [Line Items]
Stated interest rate			3.75%
Long-term debt											$ 44,500,000
BGC Partners 4.375% Senior Notes due December 15, 2025
Debt Instrument [Line Items]
Stated interest rate			4.375%		4.375%									4.375%
Long-term debt					$ 11,824,000	11,800,000
Debt issuance costs														$ 3,200,000
Total					500,000	10,500,000	13,800,000
Principal amount of debt component														300,000,000.0
Carrying amount of debt component					$ 11,800,000									$ 296,800,000
BGC Partners 4.375% Senior Notes due December 15, 2025 | Senior Notes
Debt Instrument [Line Items]
Long-term debt											$ 11,800,000
BGC Group 3.750% Senior Notes due October 1, 2024
Debt Instrument [Line Items]
Stated interest rate					3.75%							3.75%
Long-term debt					$ 0	254,814,000
Total					7,900,000	2,600,000	0
BGC Group 3.750% Senior Notes due October 1, 2024 | Senior Notes
Debt Instrument [Line Items]
Long-term debt												$ 255,500,000
New Senior Revolving Credit Agreement | Unsecured Credit Agreement November 28, 2018
Debt Instrument [Line Items]
Line of credit facility, outstanding amount					200,000,000.0
Deferred financing costs						800,000
Total					0	6,900,000	2,300,000
Senior Revolving Credit Agreement | Unsecured Credit Agreement November 28, 2018
Debt Instrument [Line Items]
Maximum revolving credit								$ 700,000,000		$ 475,000,000			$ 375,000,000.0		$ 350,000,000.0
Line of credit facility, outstanding amount					195,800,000	239,200,000
Deferred financing costs					$ 4,200,000	$ 800,000
Average interest rate (as a percent)					6.99%	7.07%
Total					$ 12,200,000	$ 4,400,000	0
Revolving Credit Facility | BGC Credit Agreement | Related Party
Debt Instrument [Line Items]
Line of credit facility, outstanding amount					0	0
Average interest rate (as a percent)	6.92%	1.00%
Total					$ 1,100,000	$ 0	$ 0
Principal amount of debt component		$ 400,000,000							$ 400,000,000							$ 400,000,000	$ 250,000,000
Proceeds from borrowings	$ 275,000,000.0