Notes Payable, Other and Short-term Borrowings - Additional Information (Detail)					6 Months Ended		12 Months Ended
	Oct. 06, 2023 USD ($)	Jun. 01, 2021 USD ($)	Sep. 27, 2019 USD ($)	Aug. 23, 2017 USD ($)	Dec. 31, 2023 USD ($) shares	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares	Oct. 07, 2023 USD ($)	May 25, 2023 USD ($)	May 22, 2023 USD ($)	May 22, 2023 BRL (R$)	Dec. 31, 2022 BRL (R$) shares	Mar. 10, 2022 USD ($)	Nov. 22, 2021 shares	Nov. 21, 2021 shares	Aug. 20, 2021 USD ($)	Aug. 20, 2021 BRL (R$)	Jul. 01, 2021 shares	Jun. 01, 2021 BRL (R$)	Jan. 25, 2021 USD ($)	Jan. 25, 2021 BRL (R$)	Dec. 31, 2020 shares	Jul. 10, 2020 USD ($)	Apr. 19, 2019 USD ($)	Apr. 08, 2019 USD ($)	Nov. 28, 2018 USD ($)	Jul. 24, 2018 USD ($)	Aug. 23, 2017 BRL (R$)	Aug. 22, 2017 USD ($)	Aug. 22, 2017 BRL (R$)
Debt Instrument [Line Items]
Carrying Amount					$ 944,326,000		$ 944,326,000	$ 1,045,966,000
Total							157,560,000
Redemption price as percentage of principal amount			101.00%
Carrying amount of debt component					$ 1,183,506,000		1,183,506,000	1,051,134,000
Interest expense							$ 77,231,000	$ 57,932,000	$ 69,329,000
Restricted Stock Units (RSUs)
Debt Instrument [Line Items]
Number of units, balance outstanding (in shares) | shares					64,942,000		64,942,000	12,046,000	11,034,000					12,046,000										8,960,000
Restricted Stock Units (RSUs) | Eligible
Debt Instrument [Line Items]
Number of units, balance outstanding (in shares) | shares					26,300,000		26,300,000
Equity Plan | Class A Common Stock
Debt Instrument [Line Items]
Shares authorized to be delivered pursuant to awards granted (in shares) | shares																500,000,000	400,000,000			600,000,000
Parent Company
Debt Instrument [Line Items]
Interest expense					$ 17,528,000	$ 30,700,000		$ 53,652,000	$ 60,772,000
BGC Partners 8.000% Senior Notes due May 25, 2028
Debt Instrument [Line Items]
Stated interest rate					8.00%		8.00%				8.00%
Carrying Amount					$ 2,748,000		$ 2,748,000	0
Debt issuance costs											$ 3,400,000
Total							10,000,000
Principal amount of notes											350,000,000
Carrying amount of debt component					2,700,000		2,700,000				$ 346,600,000
BGC Partners 8.000% Senior Notes due May 25, 2028 | Senior Notes
Debt Instrument [Line Items]
Carrying Amount										$ 2,800,000
BGC Group 8.000% Senior Notes due May 25, 2028
Debt Instrument [Line Items]
Stated interest rate	8.00%
Carrying Amount					$ 343,852,000		343,852,000	0
Total							$ 7,100,000
Redemption price as percentage of principal amount	101.00%
BGC Group 8.000% Senior Notes due May 25, 2028 | Senior Notes
Debt Instrument [Line Items]
Carrying Amount	$ 347,200,000
BGC Partners 3.750% Senior Notes due October 1, 2024
Debt Instrument [Line Items]
Stated interest rate			3.75%		3.75%		3.75%
Carrying Amount					$ 44,383,000		$ 44,383,000	298,558,000
Total							9,500,000	12,100,000	12,100,000
BGC Partners 3.750% Senior Notes due October 1, 2024 | Parent Company
Debt Instrument [Line Items]
Stated interest rate			3.75%
Carrying Amount										44,500,000
Debt issuance costs			$ 3,900,000
Principal amount of notes			300,000,000
Carrying amount of debt component			$ 296,100,000		$ 44,400,000		$ 44,400,000
BGC Partners 3.750% Senior Notes due October 1, 2024 | Senior Notes
Debt Instrument [Line Items]
Carrying Amount	$ 255,500,000
BGC Partners 3.750% Senior Notes due October 1, 2024 | Level 2
Debt Instrument [Line Items]
Stated interest rate					3.75%		3.75%
BGC Group 3.750% Senior Notes due October 1, 2024
Debt Instrument [Line Items]
Stated interest rate	3.75%				3.75%		3.75%
Carrying Amount					$ 254,814,000		$ 254,814,000	0
Total							$ 2,600,000	0	0
BGC Group 3.750% Senior Notes due October 1, 2024 | Senior Notes
Debt Instrument [Line Items]
Carrying Amount	$ 255,500,000
BGC Partners 4.375% Senior Notes due December 15, 2025
Debt Instrument [Line Items]
Stated interest rate			4.375%		4.375%		4.375%																		4.375%
Carrying Amount					$ 11,800,000		$ 11,800,000	298,165,000
Debt issuance costs																									$ 3,200,000
Total							10,500,000
Principal amount of notes																									300,000,000
Carrying amount of debt component					$ 11,800,000		$ 11,800,000																		$ 296,800,000
Interest expense								13,800,000	13,800,000
BGC Partners 4.375% Senior Notes due December 15, 2025 | Senior Notes
Debt Instrument [Line Items]
Carrying Amount										$ 11,800,000
BGC Partners 4.375% Senior Notes due December 15, 2025 | Level 2
Debt Instrument [Line Items]
Stated interest rate					4.375%		4.375%
BGC Group 4.375% Senior Notes due December 15, 2025
Debt Instrument [Line Items]
Stated interest rate	4.375%				4.375%		4.375%
Carrying Amount					$ 286,729,000		$ 286,729,000	0
Total							3,300,000	0	0
Redemption price as percentage of principal amount	101.00%
BGC Group 4.375% Senior Notes due December 15, 2025 | Senior Notes
Debt Instrument [Line Items]
Carrying Amount	$ 288,200,000				14,500,000		14,500,000
BGC Group Notes Exchange Offer
Debt Instrument [Line Items]
Debt issuance costs	$ 900,000
Unsecured Credit Agreement November 28, 2018 | New Senior Revolving Credit Agreement
Debt Instrument [Line Items]
Deferred financing costs					800,000		800,000
Unsecured Credit Agreement November 28, 2018 | New Senior Revolving Credit Agreement | Parent Company
Debt Instrument [Line Items]
Maximum revolving credit																												$ 350,000,000
Line of credit facility, outstanding amount					$ 239,200,000		239,200,000	0
Total							6,900,000	2,300,000	3,600,000
Unsecured Credit Agreement November 28, 2018 | Senior Revolving Credit Agreement
Debt Instrument [Line Items]
Maximum revolving credit															$ 375,000,000
Total							$ 4,400,000	0	0
BGC Partners 5.375% Senior Notes due July 24, 2023
Debt Instrument [Line Items]
Stated interest rate					5.375%		5.375%
Carrying Amount					$ 0		$ 0	449,243,000
BGC Partners 5.375% Senior Notes due July 24, 2023 | Parent Company
Debt Instrument [Line Items]
Stated interest rate																													5.375%
Debt issuance costs																													$ 5,800,000
Total							$ 14,500,000	25,500,000	25,500,000
Principal amount of notes																													450,000,000
Redemption price as percentage of principal amount							101.00%
Carrying amount of debt component																													$ 444,200,000
BGC Partners 5.375% Senior Notes due July 24, 2023 | Level 2
Debt Instrument [Line Items]
Stated interest rate					5.375%		5.375%
3.77% loan | Parent Company
Debt Instrument [Line Items]
Outstanding balance of the secured loan arrangements								2,000,000
3.77% loan | Secured Debt | Parent Company
Debt Instrument [Line Items]
Stated interest rate																											3.77%
Interest expense							$ 0	100,000	300,000
Debt instrument gross amount					$ 0		0																				$ 15,000,000
Book value of the fixed assets pledged								0
3.89% Loan | Parent Company
Debt Instrument [Line Items]
Outstanding balance of the secured loan arrangements								1,300,000
3.89% Loan | Secured Debt | Parent Company
Debt Instrument [Line Items]
Stated interest rate																										3.89%
Interest expense							0	100,000	200,000
Debt instrument gross amount					0		0																			$ 10,000,000
Book value of the fixed assets pledged								300,000
Unsecured Loan Agreement | Short Term Loans | Itau Unibanco S.A.
Debt Instrument [Line Items]
Maximum revolving credit																															$ 4,000,000	R$ 20,000,000
Line of credit facility, outstanding amount					0		0	2,000,000						R$ 10,000,000
Total							200,000	$ 300,000	200,000
Current interest rate								17.00%						17.00%
Unsecured Loan Agreement | Short Term Loans | Banco Daycoval S.A.
Debt Instrument [Line Items]
Maximum revolving credit		$ 4,000,000			0		$ 0	$ 0													R$ 20,000,000	$ 2,000,000	R$ 10,000,000
Total								200,000	200,000
Unsecured Loan Agreement | Short Term Loans | Brazilian Interbank Offering Rate | Itau Unibanco S.A.
Debt Instrument [Line Items]
Debt instrument, basis point							3.20%
Unsecured Loan Agreement | Short Term Loans | Brazilian Interbank Offering Rate | Banco Daycoval S.A.
Debt Instrument [Line Items]
Debt instrument, basis point		3.66%
Unsecured Credit Agreement | Intra-Day Overdraft Credit Line
Debt Instrument [Line Items]
Maximum revolving credit				$ 10,400,000									R$ 70,000,000						R$ 60,000,000											R$ 50,000,000
Line of credit facility, outstanding amount					$ 0		$ 0	0
Line of credit facility, fee percentage				1.35%
Line of credit facility, fee							$ 200,000	$ 200,000	$ 100,000
Unsecured Credit Agreement | Intra-Day Overdraft Credit Line | Itau Unibanco S.A.
Debt Instrument [Line Items]
Maximum revolving credit												$ 14,500,000						$ 12,400,000