Related Party Transactions (Detail)														1 Months Ended	3 Months Ended		12 Months Ended
	Oct. 25, 2022 USD ($) shares	May 17, 2022 USD ($) shares	Mar. 14, 2022 USD ($) $ / shares shares	Jul. 30, 2021 USD ($)	Jun. 24, 2021	Jul. 10, 2020 USD ($)	Mar. 20, 2020	Sep. 27, 2019 USD ($)	Nov. 23, 2018 USD ($) shares	Aug. 06, 2018 USD ($)	Jul. 24, 2018 USD ($)	Oct. 25, 2016 shares	Jun. 05, 2015 shares	Nov. 30, 2022 USD ($)	Mar. 31, 2023 USD ($) shares	Mar. 31, 2022 USD ($) shares	Dec. 31, 2015 USD ($)	Dec. 31, 2022 USD ($)	Jun. 05, 2022	Dec. 31, 2021 USD ($)	Feb. 25, 2021 USD ($)	Jun. 11, 2020 USD ($)	Feb. 25, 2020 USD ($)	Mar. 19, 2018 USD ($)	Nov. 04, 2016	Aug. 31, 2013 USD ($)
Related Party Transaction [Line Items]
Commissions															$ 377,288,000	$ 356,664,000
Common stock, exchange ratio									1										1
Payables to Cantor related to open derivative contracts															2,918,000			$ 10,550,000
Employee loans															352,719,000			319,612,000
Total revenues															532,867,000	506,464,000
Due to related parties															0					$ 8,300,000
Equity investment															0	343,000
Receivables from related parties															4,135,000			1,444,000
Futures Exchange Group
Related Party Transaction [Line Items]
Payments to acquire businesses				$ 4,900,000
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	$ 300,000
Receivables from related parties															$ 980,000
Loan receivable, basis spread															6.00%
Due from related parties, write-offs																		550,000
Due from related parties, remaining amount receivable															$ 430,000
Sean A. Windeatt
Related Party Transaction [Line Items]
Shares authorized to be repurchased (in shares) | shares			135,514
Exchange share price (in dollars per share) | $ / shares			$ 4.08
Number of shares redeemed (in shares) | shares			27,826
Number of non-exchangeable LPU-NEWs (in shares) | shares			135,514
Number of non-exchangeable PLPU (in shares) | shares			27,826
Average determination price (in dollars per share) | $ / shares			$ 4.84
Number of shares redeemed, value			$ 134,678
Debt securities
Related Party Transaction [Line Items]
Debt instrument, authorized repurchase amount																						$ 50,000,000
Debt instrument, remaining authorized purchase amount															$ 50,000,000
5.375% senior notes due 2023
Related Party Transaction [Line Items]
Principal amount of debt component											$ 450,000,000
Stated interest rate											5.375%
3.750% senior notes due October 1, 2024
Related Party Transaction [Line Items]
Principal amount of debt component								$ 300,000,000
Stated interest rate								3.75%
4.375% senior notes
Related Party Transaction [Line Items]
Principal amount of debt component						$ 300,000,000
Stated interest rate						4.375%									4.375%
Class B Common Stock
Related Party Transaction [Line Items]
Issuance of class A common stock (net of costs) (in shares) | shares															0	0
Class B Units | Lucera
Related Party Transaction [Line Items]
Purchase of units (in shares) | shares												9,000
Percentage of outstanding common stock owned by parent																									100.00%
Cantor
Related Party Transaction [Line Items]
Repurchase agreements															$ 0			0
Tower Bridge International Services LP | BGC Partners, Inc.
Related Party Transaction [Line Items]
Company ownership of Tower Bridge															52.00%
Tower Bridge International Services LP | Cantor
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners															48.00%
Aqua | BGC Partners, Inc. | Aqua
Related Party Transaction [Line Items]
Percentage of ownership interest															49.00%
Aqua | Cantor
Related Party Transaction [Line Items]
Investment ownership percentage															51.00%
Cantor
Related Party Transaction [Line Items]
Mark-up cost of services															7.50%
Cantor's share of net profit (loss) in Tower Bridge															$ 100,000	$ 300,000
Related party revenues															4,000,000	3,300,000
Service charges															23,900,000	21,200,000
Compensation to leased employees															15,500,000	15,500,000
Recognition of share of FX gains															1,300,000	300,000
Commissions															22,000	70,000
Investment authorization in asset-backed commercial paper program																										$ 350,000,000
Investment in asset-backed commercial paper program															0			0
Common stock, issued during the period, additional consideration									$ 0
Reverse purchase agreement outstanding															0			0
Cantor | Clearing Capital Agreement
Related Party Transaction [Line Items]
Service charges															200,000	300,000
Cantor | Futures Exchange Group
Related Party Transaction [Line Items]
Business combination, indemnified expenses (up to)				$ 1,000,000
Indemnification assets															1,000,000			1,000,000
Cantor | Revolving credit facility
Related Party Transaction [Line Items]
Principal amount of debt component										$ 400,000,000														$ 250,000,000
Debt instrument, extended term										1 year
Debt instrument, non-extension notice term										6 months
Debt instrument, basis spread on variable rate							1.00%
Line of credit facility, outstanding amount															0			0
Interest expense from affiliate															$ 0	0
CF Group Management, Inc.
Related Party Transaction [Line Items]
Right to exchange from class A to class B common stock (up to) (in shares) | shares									700,000				34,600,000
Common stock, issued during the period, additional consideration									$ 0
Cantor rights to purchase exchangeable units
Related Party Transaction [Line Items]
Right to exchange from class A to class B common stock (up to) (in shares) | shares									10,300,000						23,600,000
Limited partnership units, exchange ratio															1
Cantor rights to purchase exchangeable units | Maximum
Related Party Transaction [Line Items]
Right to exchange from class A to class B common stock (up to) (in shares) | shares													34,600,000		23,600,000
Cantor rights to purchase exchangeable units | BGC Holdings LPUs
Related Party Transaction [Line Items]
Limited partnership units, exchange ratio	1
Aggregate Cantor units as result of redemption (in shares) | shares		427,494
Aggregate consideration of Cantor units as result of redemption		$ 841,010
Number of founding partner interests as result of redemption (in shares) | shares	275,833	427,494
Aggregate consideration of Cantor units	$ 142,613	$ 105,867
Number of founding partner interests exchanged (in shares) | shares	77,507	52,681
Aggregate related party units as result of redemption (in shares) | shares	275,833
Aggregate consideration of related party units as result of redemption (in shares)	$ 397,196
Aggregate related party units (in shares) | shares	77,507	52,681
Founding partner units remaining | shares															400,000
Cantor and CFGM | Class B Common Stock
Related Party Transaction [Line Items]
Right to exchange from class A to class B common stock (up to) (in shares) | shares															23,600,000
Cantor and Freedom
Related Party Transaction [Line Items]
Receivables from freedom															$ 2,000,000			1,400,000
Receivables from Cantor related to open derivative contracts															6,500,000			3,100,000
Payables to Cantor related to open derivative contracts															6,100,000			5,800,000
Payables to Cantor related to pending equity trades															716,700,000			0
Employee loans
Related Party Transaction [Line Items]
Employee loans															352,700,000			319,600,000
Compensation expense related to employee loans															13,900,000	9,900,000
Interest income															1,800,000	$ 1,200,000
CF & Co
Related Party Transaction [Line Items]
Repurchase agreements															$ 0			0
Issuance of class A common stock (net of costs) (in shares) | shares															0	0
Related party expenses															$ 0	$ 0
Securities loaned															0			0
Guarantee fees															31,000	31,000
CF & Co | 5.375% senior notes due 2023
Related Party Transaction [Line Items]
Advisory fees											$ 200,000
CF & Co | 5.375% senior notes due 2023 | Underwriting fees
Related Party Transaction [Line Items]
Related party expenses											$ 300,000
CF & Co | 4.375% senior notes
Related Party Transaction [Line Items]
Purchased senior notes															14,500,000
CF & Co | 4.375% senior notes | Underwriting fees
Related Party Transaction [Line Items]
Related party expenses						$ 200,000
Castle Oak | 3.750% senior notes due October 1, 2024 | Underwriting fees
Related Party Transaction [Line Items]
Related party expenses								$ 200,000
Cantor Fitzgerald Relief Fund
Related Party Transaction [Line Items]
Remaining liability associated with charitable contributions															0			0
Cantor Fitzgerald Relief Fund | Other expenses
Related Party Transaction [Line Items]
Charitable contributions																	$ 40,000,000
Additional Cantor Fitzgerald Relief Fund
Related Party Transaction [Line Items]
Remaining expense related to charitable contributions															6,400,000			6,400,000
Additional Cantor Fitzgerald Relief Fund | Accounts payable and accrued liabilities
Related Party Transaction [Line Items]
Remaining liability associated with charitable contributions															9,200,000			$ 9,200,000
Aurel BGC SAS | Cantor
Related Party Transaction [Line Items]
Fees payable															0	0
Total revenues															$ 0	$ 0
Aurel BGC SAS | Cantor
Related Party Transaction [Line Items]
Percentage of revenue shared between related parties					80.00%
Revenue sharing agreement, term					12 months
Aqua
Related Party Transaction [Line Items]
Interest income, related party														$ 0