Related Party Transactions - Transactions with Executive Officers and Directors (Details)														1 Months Ended					3 Months Ended
	Jan. 02, 2024 $ / shares shares	Sep. 21, 2023 $ / shares shares	Jul. 12, 2023 USD ($)	Jul. 12, 2023 GBP (£)	Jul. 11, 2023 GBP (£)	Jul. 10, 2023 USD ($) $ / shares shares	Jul. 01, 2023 USD ($) shares	Jun. 30, 2023 USD ($) shares	Jun. 08, 2023 $ / shares shares	Jun. 02, 2023 $ / shares shares	May 18, 2023 USD ($) $ / shares shares	Apr. 18, 2023 $ / shares shares	Apr. 01, 2021 shares	Mar. 31, 2024 shares	Feb. 29, 2024 shares	Jan. 31, 2024 shares	Apr. 30, 2023 shares	Mar. 31, 2023 shares	Mar. 31, 2024 USD ($) $ / shares shares	Mar. 31, 2023 $ / shares shares
Related Party Transaction [Line Items]
Deed of amendment, notice period			24 months	24 months
Share-based payment arrangement, decrease for tax withholding obligation | $																			$ 11,400,000
Repurchase of class A common stock (in shares)														1,055,000	6,586,000	3,609,000			11,250,000	846,000
Class A Common Stock
Related Party Transaction [Line Items]
Share price (in dollars per share) | $ / shares						$ 4.45
Repurchase of class A common stock (in shares)																		846,000	9,820,280	845,890
Issuance of common stock (in shares)																			46,674	13,303
Equity-based compensation (in shares)																			4,977,409	2,096,003
Stock repurchased, weighted average price (in dollars per share) | $ / shares																			$ 7.11	$ 4.97
Shares granted in period (in shares)							600,000,000
Class B Common Stock
Related Party Transaction [Line Items]
Issuance of common stock (in shares)							64,000,000												0	0
Restricted Stock Units (RSUs)
Related Party Transaction [Line Items]
Share-based payment arrangement, decrease for tax withholding obligation | $							$ 74,000,000	$ 49,200,000
Aggregate estimated grant date fair value | $			$ 3,986,600																$ 20,618,000
Shares granted in period (in shares)							25,300,000
Restricted Stock Units (RSUs) | Mr. Windeatt
Related Party Transaction [Line Items]
Share-based payment arrangement, decrease for tax withholding obligation | $						$ 780,333
Vested in period (in shares)						720,509
Related Party
Related Party Transaction [Line Items]
Issuance of common stock (in shares)																			0	0
Shares withheld for tax withholding obligation, price per share (in dollars per share) | $ / shares											$ 4.61
Related Party | Mr. Lutnick
Related Party Transaction [Line Items]
Determination amount | $											$ 6,650,000
Related Party | Mr. Windeatt
Related Party Transaction [Line Items]
Drawings, aggregate amount, per year | £				£ 700,000	£ 600,000
Related Party | Class A Common Stock | Mr. Merkel
Related Party Transaction [Line Items]
Repurchase of class A common stock (in shares)										150,000
Stock repurchased, weighted average price (in dollars per share) | $ / shares										$ 4.21
Grants in period, net (in shares)											196,525
Related Party | Class A Common Stock | Mr. Lutnick
Related Party Transaction [Line Items]
Grants in period, net (in shares)											5,710,534
Related Party | Class A Common Stock | Reporting Person
Related Party Transaction [Line Items]
Repurchase of class A common stock (in shares)	136,891	474,808
Stock repurchased, weighted average price (in dollars per share) | $ / shares	$ 6.98	$ 5.29
Related Party | Class A Common Stock | Ms. Bell
Related Party Transaction [Line Items]
Repurchase of class A common stock (in shares)												21,786
Stock repurchased, weighted average price (in dollars per share) | $ / shares												$ 4.59
Related Party | NPU-CV, PSU-CV & PSU | Mr. Merkel
Related Party Transaction [Line Items]
Shares redeemed in period | $											$ 0
Related Party | NPSU-CV | Mr. Merkel
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											148,146
Related Party | PSU-CV | Mr. Merkel
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											33,585
Related Party | PSU | Mr. Merkel
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											74,896
Related Party | PSU | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period | $											$ 0
Related Party | NPPSU-CV & PPSU-CV | Mr. Merkel
Related Party Transaction [Line Items]
Shares redeemed in period | $											$ 843,750
Related Party | NPPSU-CV | Mr. Merkel
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											148,146
Determination amount | $											$ 681,250
Related Party | PPSU-CV | Mr. Merkel
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											33,585
Determination amount | $											$ 162,500
Related Party | Share-Based Payment Arrangement | Class A Common Stock
Related Party Transaction [Line Items]
Shares granted in period (in shares)								1,000,000
Related Party | Share-Based Payment Arrangement | Class A Common Stock | Mr. Merkel
Related Party Transaction [Line Items]
Shares granted in period (in shares)											256,627
Related Party | Share-Based Payment Arrangement | Class A Common Stock | Mr. Lutnick
Related Party Transaction [Line Items]
Grants in period, net (in shares)											232,610
Related Party | Share-Based Payment Arrangement | Class A Common Stock | Mr. Lutnick | Exchangeable PSU
Related Party Transaction [Line Items]
Shares granted in period (in shares)											520,380
Related Party | Share-Based Payment Arrangement | Class A Common Stock | Mr. Lutnick | Non-exchangeable PSU
Related Party Transaction [Line Items]
Shares granted in period (in shares)											11,332,727
Related Party | Non-exchangeable PSUs & PPSUs | Prior To 5/18/2023 | Mr. Lutnick
Related Party Transaction [Line Items]
Determination amount | $											$ 474,195
Related Party | Non-exchangeable PSU | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											11,332,727
Related Party | Non-exchangeable PSU | Prior To 5/18/2023 | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											7,879,736
Related Party | Non-exchangeable PPSU | Prior To 5/18/2023 | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											103,763
Related Party | Incrementally Monetized Non-exchangeable PSUs & PPSUs | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period | $											$ 6,650,000
Related Party | Incrementally Monetized Non-exchangeable PSUs & PPSUs | On 5/18/2023 | Mr. Lutnick
Related Party Transaction [Line Items]
Determination amount | $											$ 6,175,805
Related Party | Incrementally Monetized Non-exchangeable PSU | On 5/18/2023 | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											3,452,991
Related Party | Incrementally Monetized Non-exchangeable PPSU | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											1,451,805
Related Party | Incrementally Monetized Non-exchangeable PPSU | On 5/18/2023 | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											1,348,042
Related Party | Exchangeable PSU | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											520,380
Related Party | Non-exchangeable HDU | Mr. Lutnick
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)											1,474,930
Related Party | Non-exchangeable HDU | Mr. Lutnick | BGC Partners
Related Party Transaction [Line Items]
Shares redeemed in period | $											$ 2,100,000
Related Party | Non-exchangeable HDU | Mr. Lutnick | Newmark
Related Party Transaction [Line Items]
Shares redeemed in period | $											$ 9,148,000
Related Party | Restricted Stock Units (RSUs)
Related Party Transaction [Line Items]
Shares granted in period (in shares)								16,900,000
Related Party | Exchangeable Limited Partnership Units
Related Party Transaction [Line Items]
Shares redeemed in period (in shares)								1,500,000
Related Party | Exchangeable Limited Partnership Units | Reporting Person
Related Party Transaction [Line Items]
Repurchase of class A common stock (in shares)									128,279
Stock repurchased, weighted average price (in dollars per share) | $ / shares									$ 4.79
Shares granted in period (in shares)																	128,279
Related Party | Non-exchangeable LPUs | Reporting Person
Related Party Transaction [Line Items]
Shares granted in period (in shares)													128,279