Commitments, Contingencies and Guarantees - Summary of Contractual Obligations (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Oct. 06, 2023	May 25, 2023	Jul. 10, 2020	Sep. 27, 2019
Long-Term Debt, Fiscal Year Maturity [Abstract]
Total	$ 1,190,000,000
Less Than 1 Year	540,000,000
1-3 Years	300,000,000
3-5 Years	350,000,000
More Than 5 Years	0
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Total	189,186,000
Less Than 1 Year	31,594,000
1-3 Years	48,028,000
3-5 Years	32,624,000
2029 and thereafter	76,940,000
Finance Lease, Liability, to be Paid [Abstract]
Total	5,077,000
Less Than 1 Year	1,712,000
1-3 Years	2,738,000
3-5 Years	627,000
2029 and thereafter	0
Other Commitment, Fiscal Year Maturity [Abstract]
Total	12,744,000
Less Than 1 Year	12,744,000
1-3 Years	0
3-5 Years	0
More Than 5 Years	0
Contractual Obligation, Fiscal Year Maturity [Abstract]
Total	1,573,469,000
Less Than 1 Year	644,630,000
1-3 Years	429,370,000
3-5 Years	422,529,000
More Than 5 Years	76,940,000
Interest on Long-term Dent and Collateralized Borrowings Maturity [Abstract]
Total	157,560,000
Less Than 1 Year	49,815,000
1-3 Years	68,467,000
3-5 Years	39,278,000
More Than 5 Years	0
Interest on Short-term Borrowings [Abstract]
Total	71,000
Less Than 1 Year	71,000
1-3 Years	0
3-5 Years	0
More Than 5 Years	0
One-time Transition Tax [Abstract]
Total	18,831,000
Less Than 1 Year	8,694,000
1-3 Years	10,137,000
3-5 Years	0
More Than 5 Years	$ 0
Transition tax on deemed repatriation of foreign subsidiaries earnings payment period	8 years
Contractual obligation, charitable contribution	$ 12,700,000
Total	944,326,000	$ 1,045,966,000
Unsecured senior revolving credit agreement | Unsecured Credit Agreement February 26, 2021
One-time Transition Tax [Abstract]
Carrying amount of long-term debt	135,000,000
BGC Group 3.750% Senior Notes due October 1, 2024
Interest on Long-term Dent and Collateralized Borrowings Maturity [Abstract]
Total	$ 2,600,000	0	$ 0
One-time Transition Tax [Abstract]
Stated interest rate	3.75%			3.75%
Total	$ 254,814,000	0
BGC Group 4.375% Senior Notes due December 15, 2025
Interest on Long-term Dent and Collateralized Borrowings Maturity [Abstract]
Total	$ 3,300,000	0	0
One-time Transition Tax [Abstract]
Stated interest rate	4.375%			4.375%
Total	$ 286,729,000	0
BGC Group 8.000% Senior Notes due May 25, 2028
Interest on Long-term Dent and Collateralized Borrowings Maturity [Abstract]
Total	7,100,000
One-time Transition Tax [Abstract]
Stated interest rate				8.00%
Total	343,852,000	0
BGC Partners 3.750% Senior Notes due October 1, 2024
Interest on Long-term Dent and Collateralized Borrowings Maturity [Abstract]
Total	$ 9,500,000	12,100,000	$ 12,100,000
One-time Transition Tax [Abstract]
Stated interest rate	3.75%						3.75%
Total	$ 44,383,000	298,558,000
BGC Partners 4.375% Senior Notes due December 15, 2025
Interest on Long-term Dent and Collateralized Borrowings Maturity [Abstract]
Total	$ 10,500,000
One-time Transition Tax [Abstract]
Stated interest rate	4.375%					4.375%	4.375%
Principal amount of notes						$ 300,000,000
Total	$ 11,800,000	298,165,000
BGC Partners 4.375% Senior Notes due December 15, 2025 | Unsecured senior revolving credit agreement
One-time Transition Tax [Abstract]
Debt instrument gross amount	11,800,000
BGC Partners 8.000% Senior Notes due May 25, 2028
Interest on Long-term Dent and Collateralized Borrowings Maturity [Abstract]
Total	$ 10,000,000
One-time Transition Tax [Abstract]
Stated interest rate	8.00%				8.00%
Principal amount of notes					$ 350,000,000
Total	$ 2,748,000	$ 0
Debt and Collateralized Borrowings | BGC Group 3.750% Senior Notes due October 1, 2024
One-time Transition Tax [Abstract]
Stated interest rate	3.75%
Debt instrument gross amount	$ 254,800,000
Principal amount of notes	255,500,000
Total	255,500,000
Interest expense	$ 7,100,000
Debt and Collateralized Borrowings | BGC Group 4.375% Senior Notes due December 15, 2025
One-time Transition Tax [Abstract]
Stated interest rate	4.375%
Debt instrument gross amount	$ 286,700,000
Principal amount of notes	288,200,000
Total	288,200,000
Interest expense	$ 24,500,000
Debt and Collateralized Borrowings | BGC Group 8.000% Senior Notes due May 25, 2028
One-time Transition Tax [Abstract]
Stated interest rate	8.00%
Debt instrument gross amount	$ 343,900,000
Principal amount of notes	347,200,000
Total	347,200,000
Interest expense	$ 122,300,000
Debt and Collateralized Borrowings | BGC Partners 3.750% Senior Notes due October 1, 2024
One-time Transition Tax [Abstract]
Stated interest rate	3.75%
Debt instrument gross amount	$ 44,400,000
Principal amount of notes	44,500,000
Total	44,500,000
Interest expense	$ 1,200,000
Debt and Collateralized Borrowings | BGC Partners 4.375% Senior Notes due December 15, 2025
One-time Transition Tax [Abstract]
Stated interest rate	4.375%
Principal amount of notes	$ 11,800,000
Total	11,800,000
Interest expense	$ 1,000,000
Debt and Collateralized Borrowings | BGC Partners 8.000% Senior Notes due May 25, 2028
One-time Transition Tax [Abstract]
Stated interest rate	8.00%
Debt instrument gross amount	$ 2,700,000
Principal amount of notes	2,800,000
Total	2,800,000
Interest expense	1,000,000
One-time Transition Tax
One-time Transition Tax [Abstract]
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	$ 18,800,000