Related Party Transactions - Other Transactions (Details) - USD ($)		1 Months Ended	3 Months Ended
	Oct. 25, 2016	Nov. 30, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Feb. 15, 2022	Feb. 25, 2021	Nov. 04, 2016
Related Party Transaction [Line Items]
Receivables from related parties			$ 5,254,000		$ 2,717,000
Related Party
Related Party Transaction [Line Items]
Interest income			3,200,000	$ 1,800,000
Due from related parties, write-offs						$ 600,000
Receivables from related parties					$ 400,000
Related Party | Subordinated Loan Agreement with Aqua
Related Party Transaction [Line Items]
Interest income		$ 0
Aqua | Cantor | Related Party
Related Party Transaction [Line Items]
Investment ownership percentage								51.00%
Aqua | Related Party
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
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
Related Party Transaction [Line Items]
Percentage of ownership interest								49.00%
Lucera | Related Party | Class B Units
Related Party Transaction [Line Items]
Purchase of units (in shares)	9,000
Percentage of outstanding common stock owned by parent									100.00%