Related Party Transactions - Other Transactions (Details) - USD ($)				1 Months Ended	12 Months Ended
	Jul. 01, 2023	Nov. 04, 2016	Oct. 25, 2016	Nov. 30, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2023	Feb. 15, 2022	Feb. 25, 2021	Nov. 03, 2016
Related Party Transaction [Line Items]
Payables to related parties							$ 8,300,000
Equity investment					$ 0	$ 588,000	1,115,000
Receivables from related parties					2,717,000	1,444,000
Total revenues					2,025,401,000	1,795,302,000	2,015,364,000
Conversion of stock, shares converted (in shares)	64,000,000
Minimum number of shares required to be issued (in shares)	75,000,000
Related Party
Related Party Transaction [Line Items]
Interest income					15,100,000	7,500,000	10,000,000
Due from related parties, write-offs						600,000
Receivables from related parties								$ 400,000
Total revenues					16,000,000	14,700,000	14,900,000
Cash and collateral posted expense					$ 2,200,000	800,000	$ 700,000
Related Party | Subordinated Loan Agreement with Aqua
Related Party Transaction [Line Items]
Interest income				$ 0
Cantor | Class B Common Stock
Related Party Transaction [Line Items]
Investment owned, balance (in shares)					93,300,000
Cantor | Class A Common Stock
Related Party Transaction [Line Items]
Investment owned, balance (in shares)					0
CFGM | Class B Common Stock
Related Party Transaction [Line Items]
Investment owned, balance (in shares)					3,000,000
CFGM | Class A Common Stock
Related Party Transaction [Line Items]
Investment owned, balance (in shares)					0
Aqua | Cantor
Related Party Transaction [Line Items]
Investment ownership percentage					51.00%
Aqua
Related Party Transaction [Line Items]
Increase in authorization amount for loans and investments, other credit support arrangements									$ 1,000,000	$ 1,000,000
Authorization amount for loans and investments, other credit support arrangements										$ 21,200,000
Equity investment					$ 0	$ 600,000
Aqua | Related Party | Subordinated Loan Agreement with Aqua
Related Party Transaction [Line Items]
Receivables from related parties					$ 1,000,000
Aqua | Aqua | BGC Partners, Inc.
Related Party Transaction [Line Items]
Percentage of ownership interest					49.00%
Lucera
Related Party Transaction [Line Items]
Payments to acquire businesses		$ 24,200,000
Business combination, consideration, post-closing adjustment		$ 4,800,000
Lucera | Class B Units
Related Party Transaction [Line Items]
Percentage of ownership interest											20.00%
Purchase of units (in shares)			9,000
Percentage of outstanding common stock owned by parent		100.00%