Related Party Transactions - Transfer of Employees to Newmark and Other Related Party Transactions (Details) shares in Millions		1 Months Ended
	May 01, 2018 USD ($) employee	Jul. 31, 2020 USD ($)	Feb. 28, 2019 USD ($)	Oct. 31, 2018 USD ($) shares	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Related Party Transaction
Total stockholders’ equity					$ 1,259,680,000	$ 1,277,927,000
Redeemable partnership interests					$ 17,404,000	$ 20,947,000	$ 20,947,000	$ 20,045,000
CCRE
Related Party Transaction
Number of employees transferred | employee	5
Proceeds from limited partnership units				$ 6,900,000
Total stockholders’ equity	$ 6,900,000
Redeemable partnership interests	2,200,000
Maximum revenue share to related party in first two years	$ 3,300,000
Payments to related party		$ 3,300,000
CCRE | Newmark Holdings, L.P.
Related Party Transaction
Proceeds from issuance of EPUs				6,700,000
Limited partnership unit cash distributions				$ 200,000
Issuance of additional limited partners units in exchange (in shares) | shares				2.2
Issuance of additional limited partners units in exchange for cash payment				$ 500,000
Issuance of additional limited partnership units with capital account				$ 2,200,000
Cantor Fitzgerald Limited Partnership And B G C Partners Incorporation | Government Sponsored Enterprise Loans
Related Party Transaction
Maximum amount per loan			$ 100,000,000
Limit on loans that have not yet been acquired or sold			250,000,000
Limit on loans outstanding			$ 250,000,000