Condensed Consolidated Statements of Changes in Equity (Parenthetical) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Grant of exchangeability and redemption of limited partnership interests, issuance of shares (in shares)	11,939,546	8,446,093	23,647,165	49,033,008
Repurchase of class A common stock (in shares)	12,397,000	24,433,000	21,142,000	41,940,000
Forfeiture of class A common stock (in shares)	43,000	56,000	47,000	140,000
Cantor purchase of Cantor units from BGC Holdings upon redemption of FPUs (in shares)			480,175	2,768,060
Class A Common Stock
Equity-based compensation (in shares)	448,014	213,459	3,018,337	1,940,975
Grant of exchangeability and redemption of limited partnership interests, issuance of shares (in shares)	11,940,000	8,446,000	23,654,000	49,033,000
Issuance of class A common stock (net of costs) (in shares)	101,786	100,128	445,245	366,043
Repurchase of class A common stock (in shares)	12,396,735	24,432,718	21,142,045	41,939,724
Forfeiture of class A common stock (in shares)	43,388	56,423	47,807	140,188
Issuance of Class A common stock and RSUs for acquisitions (in shares)	0	343,000	1,186,000	1,130,000
Class A Common Stock | Partnership Units
Redemption of FPUs (in shares)	27,087	56,730	96,447	718,434
Class A Common Stock | Smith Mack
Issuance of Class A common stock and RSUs for acquisitions (in shares)		342,162	1,192,907	1,129,630