Earnings Per Share - Narrative (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)	16.4	15.5	16.5	15.8
Contingent Class A Common Stock \| BGC Holdings Partnership Unit
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)			64.0	54.2
Contingent Class A Common Stock \| Limited Partnership Unit
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)			64.0	54.2
Contingent Class A Common Stock \| N Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)			64.0	54.2
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)	16.2	15.4	16.3	15.6
Restricted Stock Units (RSUs) \| Contingent Class A Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)			64.0	54.2
Earnings RSAs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)	0.2	0.1	0.2	0.2