Schedule I - Parent Company Only - Notes Payable and Other Borrowings - Additional Information (Detail) - USD ($)																			12 Months Ended
	Dec. 15, 2025	Nov. 12, 2025	Jun. 30, 2025	Jun. 05, 2025	Apr. 14, 2025	Apr. 04, 2025	Apr. 02, 2025	Oct. 01, 2024	Sep. 25, 2024	Aug. 21, 2024	Jul. 31, 2024	Jun. 10, 2024	Apr. 01, 2024	Mar. 12, 2024	Mar. 08, 2024	Oct. 06, 2023	Sep. 27, 2019	Jul. 24, 2018	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Nov. 10, 2025	Dec. 06, 2024	Nov. 08, 2024	Jun. 07, 2024	Apr. 26, 2024	Oct. 19, 2023	Oct. 07, 2023	May 25, 2023	Mar. 10, 2022	Jul. 10, 2020	Feb. 26, 2020	Nov. 28, 2018	Aug. 06, 2018	Mar. 19, 2018
Debt Instrument [Line Items]
Long-term debt																			$ 1,538,019,000	$ 1,141,709,000
Line of credit, maturity date extension (in years)																																2 years
Deferred financing costs																			13,800,000	12,000,000.0
Interest expense																			365,754,000
Redemption price as percentage of principal amount (as a percent)																	101.00%
Carrying amount of debt component																			1,775,705,000	1,337,540,000
Repayments of debt																			1,005,000,000	815,000,000	$ 623,251,000
Related Party
Debt Instrument [Line Items]
Interest income																			16,100,000	13,800,000	15,100,000
Revolving Credit Facility | BGC Credit Agreement | Related Party
Debt Instrument [Line Items]
Line of credit facility, outstanding amount																				0
Average interest rate (as a percent)		5.45%												6.92%	1.00%
Interest expense																			200,000	1,100,000	0
Principal amount of debt component															$ 400,000,000.0										$ 400,000,000.0									$ 400,000,000.0	$ 250,000,000.0
Proceeds from borrowings		$ 20,000,000.0												$ 275,000,000.0
Repayment of outstanding borrowings								$ 150,000,000.0					$ 275,000,000.0
Interest income																			3,800,000
Revolving Credit Facility | BGC Credit Agreement | Related Party | Cantor
Debt Instrument [Line Items]
Line of credit facility, outstanding amount																			$ 0	$ 0
Average interest rate (as a percent)																			6.17%	7.13%
Proceeds from borrowings						$ 120,000,000.0						$ 180,000,000.0
Repayment of outstanding borrowings			$ 77,000,000.0	$ 28,000,000.0	$ 15,000,000.0				$ 12,000,000.0		$ 18,000,000.0
Interest income																			$ 1,500,000
BGC Partners 8.000% Senior Notes due May 25, 2028
Debt Instrument [Line Items]
Stated interest rate										8.00%									8.00%										8.00%
Long-term debt										$ 500,000									$ 2,262,000	$ 2,257,000
Debt issuance costs																													$ 3,400,000
Interest expense																			200,000	200,000	10,000,000.0
Principal amount of debt component																													350,000,000.0
Carrying amount of debt component																													$ 346,600,000
Repayments of debt										$ 500,000
Debt instrument gross amount																			2,300,000
BGC Partners 8.000% Senior Notes due May 25, 2028 | Senior Notes
Debt Instrument [Line Items]
Long-term debt																$ 347,200,000												$ 2,800,000
BGC Group 3.750% Senior Notes due October 1, 2024
Debt Instrument [Line Items]
Stated interest rate																3.75%
Interest expense																			$ 0	7,900,000	2,600,000
BGC Group 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
Debt Instrument [Line Items]
Stated interest rate																	3.75%
Debt issuance costs																	$ 3,900,000
Interest expense																				1,300,000	9,500,000
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 | Parent Company
Debt Instrument [Line Items]
Stated interest rate																	3.75%
Long-term debt																												44,500,000
BGC Partners 3.750% Senior Notes due October 1, 2024 | Senior Notes
Debt Instrument [Line Items]
Long-term debt																$ 255,500,000
BGC Group 4.375% Senior Notes due December 15, 2025
Debt Instrument [Line Items]
Stated interest rate	4.375%															4.375%			4.375%					4.375%			4.375%
Long-term debt																			$ 0	287,462,000
Interest expense																			12,800,000	13,300,000	3,300,000
Redemption price as percentage of principal amount (as a percent)																101.00%
Repayments of debt	$ 288,200,000
Senior notes																			0	287,462,000
BGC Group 4.375% Senior Notes due December 15, 2025 | Senior Notes
Debt Instrument [Line Items]
Long-term debt																$ 288,200,000			$ 14,500,000
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																			$ 0	11,824,000
Debt issuance costs																															$ 3,200,000
Interest expense																			500,000	500,000	10,500,000
Principal amount of debt component																															300,000,000.0
Carrying amount of debt component																															$ 296,800,000
Repayments of debt	$ 11,800,000
Senior notes																			$ 0	11,824,000
BGC Partners 4.375% Senior Notes due December 15, 2025 | Senior Notes
Debt Instrument [Line Items]
Long-term debt																$ 288,200,000												$ 11,800,000
BGC Group 8.000% Senior Notes due May 25, 2028
Debt Instrument [Line Items]
Stated interest rate																8.00%			8.00%					8.00%			8.00%
Long-term debt																			$ 345,387,000	344,620,000
Interest expense																			28,500,000	28,500,000	7,100,000
Redemption price as percentage of principal amount (as a percent)																101.00%
Senior notes																			345,387,000	344,620,000
BGC Group 8.000% Senior Notes due May 25, 2028 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate																8.00%
Long-term debt																$ 347,200,000
BGC Group Notes Exchange Offer
Debt Instrument [Line Items]
Debt issuance costs																$ 900,000
Unsecured Credit Agreement November 28, 2018 | Senior Revolving Credit Agreement
Debt Instrument [Line Items]
Maximum revolving credit																							$ 700,000,000.0			$ 475,000,000.0				$ 375,000,000.0			$ 350,000,000.0
Line of credit facility, outstanding amount																			237,600,000
Deferred financing costs																			$ 2,400,000	$ 4,200,000
Average interest rate (as a percent)																			6.09%	6.99%
Interest expense																			$ 10,200,000	$ 12,200,000	4,400,000
Repayment of outstanding borrowings														$ 240,000,000.0
Unsecured Credit Agreement November 28, 2018 | New Senior Revolving Credit Agreement
Debt Instrument [Line Items]
Line of credit facility, outstanding amount																			240,000,000.0	195,800,000
Interest expense																			$ 0	0	6,900,000
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
Interest expense																					$ 14,500,000
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 Group 6.600% Senior Notes due June 10, 2029
Debt Instrument [Line Items]
Stated interest rate												6.60%							6.60%					6.60%
Long-term debt																			$ 496,548,000	495,546,000
Debt issuance costs												$ 5,000,000.0
Interest expense																			34,000,000.0	18,900,000
Principal amount of debt component												$ 500,000,000.0
Redemption price as percentage of principal amount (as a percent)												101.00%
Carrying amount of debt component												$ 495,000,000.0
Senior notes																			$ 496,548,000	495,546,000
BGC Group 6.150% Senior Notes due April 2, 2030
Debt Instrument [Line Items]
Stated interest rate																			6.15%			6.15%
Long-term debt																			$ 693,822,000	0
Debt issuance costs							$ 7,300,000
Interest expense																			33,200,000
Principal amount of debt component							$ 700,000,000.0
Redemption price as percentage of principal amount (as a percent)							101.00%
Carrying amount of debt component							$ 692,700,000
Senior notes																			$ 693,822,000	$ 0