Commitments, Contingencies and Guarantees - Schedule of Contractual Obligations (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Nov. 08, 2024	Aug. 21, 2024	Oct. 19, 2023	Oct. 06, 2023	May 25, 2023	Jul. 10, 2020	Sep. 27, 2019
Debt and collateralized borrowings
Total	$ 1,349,500,000
Less Than 1 Year	500,000,000
1-3 Years	0
3-5 Years	849,500,000
More Than 5 Years	0
Operating leases
Total	172,607,000
Less Than 1 Year	29,722,000
1-3 Years	46,821,000
3-5 Years	28,895,000
More Than 5 Years	67,169,000
Finance leases
Total	3,437,000
Less Than 1 Year	1,520,000
1-3 Years	1,917,000
3-5 Years	0
More Than 5 Years	0
Interest on debt and collateralized borrowings
Total	257,435,000
Less Than 1 Year	74,750,000
1-3 Years	123,757,000
3-5 Years	58,928,000
More Than 5 Years	0
Interest on Short-term borrowings
Total	55,000
Less Than 1 Year	55,000
1-3 Years	0
3-5 Years	0
More Than 5 Years	0
One-time transition tax
Total	11,382,000
Less Than 1 Year	6,962,000
1-3 Years	4,420,000
3-5 Years	0
More Than 5 Years	0
Other
Total	13,242,000
Less Than 1 Year	13,242,000
1-3 Years	0
3-5 Years	0
More Than 5 Years	0
Total contractual obligations
Total	1,807,658,000
Less Than 1 Year	626,251,000
1-3 Years	176,915,000
3-5 Years	937,323,000
More Than 5 Years	67,169,000
Stated interest rate							8.00%
Long-term debt	1,141,709,000	$ 944,326,000
Transition tax on deemed repatriation of foreign subsidiaries earnings net cumulative tax expense net of foreign tax credits	25,300,000
Transition tax on deemed repatriation of foreign subsidiaries earnings net cumulative tax expense net of foreign tax credits, net adjustment	$ 3,300,000
Transition tax on deemed repatriation of foreign subsidiaries earnings payment period	8 years
Contractual obligation, charitable contribution	$ 13,200,000
Unsecured senior revolving credit agreement | Unsecured Credit Agreement February 26, 2021
Total contractual obligations
Unsecured senior revolving credit agreement	$ 500,000,000.0
BGC Group 4.375% Senior Notes due December 15, 2025
Interest on debt and collateralized borrowings
Total			$ 0
Total contractual obligations
Stated interest rate	4.375%			4.375%		4.375%	4.375%
Long-term debt	$ 287,462,000	286,729,000
BGC Partners 4.375% Senior Notes due December 15, 2025
Interest on debt and collateralized borrowings
Total	$ 500,000	10,500,000	$ 13,800,000
Total contractual obligations
Principal amount of debt component									$ 300,000,000.0
Stated interest rate	4.375%								4.375%	4.375%
Long-term debt	$ 11,824,000	11,800,000
BGC Group 8.000% Senior Notes due May 25, 2028
Interest on debt and collateralized borrowings
Total	$ 28,500,000	7,100,000
Total contractual obligations
Stated interest rate	8.00%			8.00%		8.00%	8.00%
Long-term debt	$ 344,620,000	343,852,000
BGC Partners 8.000% Senior Notes due May 25, 2028
Interest on debt and collateralized borrowings
Total	$ 200,000	10,000,000.0
Total contractual obligations
Principal amount of debt component								$ 350,000,000
Stated interest rate	8.00%				8.00%			8.00%
Debt instrument gross amount	$ 2,300,000
Long-term debt	2,257,000	$ 2,748,000			$ 500,000
Debt and Collateralized Borrowings | Unsecured senior revolving credit agreement
Total contractual obligations
Interest expense	3,200,000
Debt and Collateralized Borrowings | BGC Group 4.375% Senior Notes due December 15, 2025
Total contractual obligations
Principal amount of debt component	288,200,000
Debt instrument gross amount	287,500,000
Interest expense	11,900,000
Debt and Collateralized Borrowings | BGC Partners 4.375% Senior Notes due December 15, 2025
Total contractual obligations
Principal amount of debt component	$ 11,800,000
Stated interest rate	4.375%
Debt instrument gross amount	$ 11,800,000
Long-term debt	11,800,000
Interest expense	500,000
Debt and Collateralized Borrowings | BGC Group 8.000% Senior Notes due May 25, 2028
Total contractual obligations
Principal amount of debt component	$ 347,200,000
Stated interest rate	8.00%
Debt instrument gross amount	$ 344,600,000
Interest expense	94,500,000
Debt and Collateralized Borrowings | BGC Partners Six Point Zero Percent Senior Notes
Total contractual obligations
Principal amount of debt component	$ 500,000,000.0
Stated interest rate	6.60%
Long-term debt	$ 495,500,000
Interest expense	146,700,000
Debt and Collateralized Borrowings | BGC Partners 8.000% Senior Notes due May 25, 2028
Total contractual obligations
Principal amount of debt component	$ 2,300,000
Stated interest rate	8.00%
Debt instrument gross amount	$ 2,300,000
Long-term debt	2,300,000
Interest expense	600,000
One-time Transition Tax
Total contractual obligations
Transition tax on deemed repatriation of foreign subsidiaries earnings net cumulative tax expense net of foreign tax credits	$ 28,600,000
Percentage of transition tax to be paid in equal installments over first five years	40.00%
Percentage of remaining transition tax to be paid in installments in years six to eight	60.00%
Percentage of remaining transition tax to be paid in installments in year six	15.00%
Percentage of remaining transition tax to be paid in installments in year seven	20.00%
Percentage of remaining transition tax to be paid in installments in year eight	25.00%
Transition tax on deemed repatriation of foreign subsidiaries earnings net cumulative remaining balance	$ 11,400,000