Condensed Consolidated Statements of Changes in Equity (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Grant of exchangeability and redemption of limited partnership interests, issuance of shares (in shares)		15,974,143		29,118,664
Repurchase of class A common stock (in shares)	10,688,000	9,814,000	21,938,000	10,660,000
Cantor purchase of Cantor units from BGC Holdings upon redemption of RFUs (in shares)		6,368,964		6,368,964
Dividends declared per share of common stock (in dollars per share)	$ 0.02	$ 0.01	$ 0.03	$ 0.02
Dividends declared and paid per share of common stock (in dollars per share)	$ 0.02	$ 0.01	$ 0.03	$ 0.02
Partnership Units
Redemption of FPUs (in shares)		133,135		156,049
Class A Common Stock
Equity-based compensation (in shares)	3,798,747	534,010	8,776,156	2,630,013
Grant of exchangeability and redemption of limited partnership interests, issuance of shares (in shares)	753,000	17,082,000	1,118,000	30,226,000
Issuance of common stock (in shares)	122,220	166,280	168,894	179,583
Repurchase of class A common stock (in shares)	9,431,127	9,813,827	19,251,407	10,659,717
Forfeiture of class A common stock (in shares)	36,465	189,726	672,632	238,927
Issuance of Class A common stock and RSUs for acquisitions (in shares)	0	3,494,000	472,255	4,152,000
Class A Common Stock | Smith Mack
Issuance of Class A common stock and RSUs for acquisitions (in shares)		4,432,568		5,090,814