Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Consolidated net income (loss)	$ 153,488	$ 50,918	$ 66,816
Adjustments to reconcile consolidated net income (loss) to net cash provided by (used in) operating activities:
Gain on Insurance Business Disposition	(312,941)	0	0
Fixed asset depreciation and intangible asset amortization	81,874	85,422	81,868
Employee loan amortization and reserves on employee loans	217,655	67,032	35,650
Equity-based compensation and allocations of net income to limited partnership units and FPUs	256,164	183,545	170,625
Deferred compensation expense	347	630	5,879
Losses (gains) on equity method investments	(6,706)	(1,126)	(4,115)
Realized losses (gains) on marketable securities	0	(289)	(3,528)
Unrealized losses (gains) on marketable securities	(56)	(69)	(3,204)
Loss (gains) on other investments	73	431	(18,163)
Amortization of discount (premium) on notes payable	3,592	4,187	3,223
Impairment of fixed assets, intangible assets and investments	11,246	11,431	4,536
Deferred tax provision (benefit)	(11,947)	(16,549)	(4,196)
Change in estimated acquisition earn-out payables	4,285	4,661	5,622
Forfeitures of Class A common stock	(553)	0	(139)
Other	(4,915)	2,730	(5,682)
Consolidated net income (loss), adjusted for non-cash and non-operating items	391,606	392,954	335,192
Decrease (increase) in operating assets:
Securities owned	17,626	(1,346)	883
Receivables from broker-dealers, clearing organizations, customers and related broker-dealers	(482,669)	246,498	389,058
Accrued commissions receivable, net	(101,314)	44,389	(22,287)
Loans, forgivable loans and other receivables from employees and partners, net	(38,571)	(149,145)	(119,469)
Receivables from related parties	8,377	5,465	(4,215)
Other assets	1,543	(20,074)	5,239
Increase (decrease) in operating liabilities:
Repurchase agreements	0	0	(986)
Securities loaned	0	(13,902)	(1,238)
Accrued compensation	17,989	13,752	(7,231)
Payables to broker-dealers, clearing organizations, customers and related broker-dealers	477,083	(236,314)	(353,281)
Payables to related parties	18,596	(37,613)	36,855
Accounts payable, accrued and other liabilities	106,919	57,949	(17,420)
Net cash provided by (used in) operating activities	417,185	302,613	241,100
CASH FLOWS FROM INVESTING ACTIVITIES:
Gross proceeds from Insurance Business Disposition	534,916	0	0
Cash and restricted cash transferred as part of Insurance Business Disposition	(369,407)	0	0
Purchases of fixed assets	(10,112)	(30,829)	(46,665)
Capitalization of software development costs	(43,178)	(54,342)	(50,833)
Purchase of equity method investments	(1,115)	(1,458)	(1,715)
Proceeds from equity method investments	10,029	4,326	3,737
Payments for acquisitions, net of cash acquired	0	(7,871)	28,261
Proceeds from sale of marketable securities	0	14,237	24,626
Purchase of other assets	0	(2,000)	0
Net cash provided by (used in) investing activities	121,133	(77,937)	(42,589)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayments of long-term debt and collateralized borrowings	(566,244)	(357,789)	(332,378)
Issuance of long-term debt and collateralized borrowings, net of deferred issuance costs	298,419	524,396	709,849
Earnings distributions to limited partnership interests and other noncontrolling interests	(52,169)	(63,109)	(113,673)
Redemption and repurchase of limited partnership interests	(110,565)	(47,613)	(43,270)
Dividends to stockholders	(15,098)	(60,440)	(192,442)
Repurchase of Class A common stock	(365,398)	(6)	(1,236)
Cancellation of RSUs in satisfaction of withholding tax requirements	0	0	(458)
Proceeds from sale of Cantor Units in BGC Holdings	7,894	0	0
Pre-acquisition cash capital contribution to Futures Exchange Group	3,845	0	0
Acquisition of Futures Exchange Group	(9,022)	0	0
Payments on acquisition earn-outs	(11,199)	(8,540)	(8,146)
Net cash provided by (used in) financing activities	(819,537)	(13,101)	18,246
Effect of exchange rate changes on Cash and cash equivalents, and Cash segregated under regulatory requirements	(5,388)	993	2,630
Net increase (decrease) in cash and cash equivalents	(286,607)	212,568	219,387
Cash and cash equivalents, and Cash segregated under regulatory requirements at beginning of period	853,406	640,838	421,451
Cash and cash equivalents, and Cash segregated under regulatory requirements at end of period	566,799	853,406	640,838
Supplemental cash information:
Cash paid during the period for taxes	43,357	41,910	47,997
Cash paid during the period for interest	66,450	69,572	51,776
Supplemental non-cash information:
Issuance of Class A common stock upon exchange of limited partnership interests	157,547	11,388	26,146
Issuance Of Class Common Stock And Limited Partnership Interests For Acquisitions	1,160	1,578	3,040
ROU assets and liabilities	$ 7,367	$ 34,456	$ 169,065