Stock Transactions and Unit Redemptions - Gross Unit Redemptions and Share Repurchases of Class A Common Stock Table Footnote (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended							12 Months Ended
	Dec. 31, 2023	Nov. 30, 2023	Oct. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Weighted-average price for redemption of limited partnership units (in dollars per shares)											$ 4.71
Repurchase of Class A common stock (in shares)	0	1,204,000	4,269,000	8,087,000	9,814,000	846,000	5,945,000	12,397,000	8,745,000	0	24,220,000	27,087,000
Aggregate purchase price of Class A common stock											$ 114,580	$ 103,888	$ 365,398
Shares withheld to satisfy tax liabilities (in shares)			1,000,000
Share-based payment arrangement, decrease for tax withholding obligation			$ 5,000
Shares withheld for tax withholding obligation (dollars per share)			$ 5.21
Class A Common Stock
Class of Stock [Line Items]
Other issuances of BGC Class A common stock (in shares)											2,946,000	501,000
Common stock, shares issued for redemption/cancellation of units (in shares)											20,500,000	20,900,000
Common stock, shares issued for exchange of units (in shares)											13,600,000	10,800,000
Repurchase of Class A common stock (in shares)											23,250,551	27,086,884	68,253,498
Repurchase of Class A shares including shares withheld for RSAs (in shares)											24,200,000
Aggregate purchase price of Class A common stock											$ 119,600	$ 103,900
Weighted-average price of Class A common stock (in dollars per share)											$ 4.94	$ 3.84
Number of shares repurchased (in shares)												27,100,000
Limited Partnership
Class of Stock [Line Items]
Redeemed limited partnership units (in shares)											300,000	1,300,000
Aggregate redemption price of limited partnership units											$ 1,400	$ 4,900
Weighted-average price for redemption of limited partnership units (in dollars per shares)												$ 3.87
Common stock, shares issued for redemption/cancellation of units (in shares)											400,000
Other Ownership Interest
Class of Stock [Line Items]
Redeemed limited partnership units (in shares)											200,000	100,000
Aggregate redemption price of limited partnership units											$ 800	$ 400
Weighted-average price for redemption of limited partnership units (in dollars per shares)												$ 3.41
Weighted-average price for redemption of founding/working partner units (in dollars per share)											$ 5.11