CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities
Net income (loss) attributable to non-controlling interests	$ 71,247	$ 30,272	$ 32,110
Adjustments to reconcile net income to net cash provided by (used in) operating activities
Depreciation and amortization of furniture, equipment and leasehold improvements	10,834	9,924	7,605
Deferred income taxes	3,551	6,457	(14,616)
Amortization of intangible assets	350	0	0
Amortization of notes receivable	18,124	15,966	13,741
Amortization of debt issuance costs	170	219	248
Write-off of debt issuance costs	222	5	61
Provision for (reversal of) credit losses	(137)	(5)	(2,955)
Share-based compensation	45,506	16,940	15,914
Amortization of right-of-use lease assets	26,101	27,281	26,804
Gain on repurchase of senior secured notes	0	(51)	(235)
Decrease (increase) in operating assets:
Deposits with clearing organizations	(20,203)	(1,015)	(10,723)
Receivable from brokers, dealers and clearing organizations	43,218	(78,619)	(36,175)
Receivable from customers	(208,837)	142,877	21,641
Income tax receivable	5,700	(7,199)	0
Securities purchased under agreements to resell	5,842	(5,842)	935
Securities owned	(312,894)	(296,718)	135,910
Notes receivable	(23,415)	(21,111)	(17,253)
Corporate-owned life insurance			19,849
Corporate-owned life insurance	(9,839)	(11,535)
Other assets	(14,641)	289	(3,437)
Increase (decrease) in operating liabilities:
Drafts payable	12,659	9,002	0
Payable to brokers, dealers and clearing organizations	(108,074)	(188,116)	127,949
Payable to customers	(11,452)	(87,188)	(483)
Securities sold under agreements to repurchase	291,372	479,373	(116,313)
Securities sold but not yet purchased	67,216	(21,092)	(19,190)
Accrued compensation	42,407	13,227	(107,350)
Income tax payable	3,963	(4,130)	(9,406)
Accounts payable and other liabilities	(47,158)	(48,021)	(139)
Cash provided by/(used in) operating activities	(108,168)	(18,810)	64,492
Cash flows from investing activities
Purchase of furniture, equipment and leasehold improvements	(5,148)	(17,056)	(16,311)
Acquisitions, net of cash consideration	(2,350)	(2,929)	0
Proceeds from the settlement of Corporate-owned life insurance	3,659	4,424	2,174
Cash used in investing activities	(3,839)	(15,561)	(14,137)
Cash flows from financing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	(6,845)	(6,452)	(7,044)
Issuance of Class A non-voting common stock	64	75	127
Repurchase of Class A non-voting common stock for cancellation	(9,603)	(35,124)	(60,636)
Payments for employee taxes withheld related to vested share-based awards	(6,844)	(5,907)	(2,283)
Distribution to non-controlling interests	0	(198)	(90)
Redemption on redeemable non-controlling interests	500
Redemption on redeemable non-controlling interests		(26,155)	(103,536)
Repurchase of senior secured notes	0	(1,000)	(10,950)
Redemption of senior secured notes	(113,050)	0	0
Increase (decrease) in bank call loans, net	252,100	0	(69,500)
Cash provided by/(used in) financing activities	116,322	(74,761)	(253,912)
Net increase/(decrease) in cash and cash equivalents and restricted cash	4,315	(109,132)	(203,557)
Cash and cash equivalents and restricted cash, beginning of year	28,835	137,967	341,524
Cash and cash equivalents and restricted cash, end of year	33,150	28,835	137,967
Reconciliation of cash and cash equivalents and restricted cash within the consolidated balance sheet:
Cash and cash equivalents	33,150	28,835	112,433
Restricted cash	0	0	25,534
Total cash and cash equivalents and restricted cash	33,150	28,835	137,967
Schedule of non-cash financing activities
Employee share plan issuance	13,951	9,376	4,288
Fair value of non-cash assets acquired	3,165	6,658	0
Fair value of liabilities assumed in acquisition	840	1,544	0
Contingent consideration for BondWave LLC	0	(1,395)	0
Supplemental disclosure of cash flow information
Cash paid during the year for interest	88,795	68,399	22,810
Cash paid during the year for income taxes, net	$ 21,272	$ 20,576	$ 37,512