Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues
Revenues	$ 206,715	$ 172,284	$ 614,693	$ 555,299
Expenses
Employee compensation and benefits	58,431	48,872	176,485	149,570
Depreciation and amortization	18,728	17,561	55,284	51,027
Technology and communications	18,553	15,339	53,375	45,573
Professional and consulting fees	6,989	9,181	21,053	24,331
Occupancy	3,835	3,503	10,974	10,313
Marketing and advertising	2,898	2,100	7,741	8,403
Clearing costs	4,387	3,665	13,420	12,392
General and administrative	5,839	5,154	15,467	15,698
Total expenses	119,660	105,375	353,799	317,307
Operating income	87,055	66,909	260,894	237,992
Other income (expense)
Interest income	6,953	6,590	19,327	16,151
Interest expense	(346)	(164)	(1,283)	(347)
Equity in earnings of unconsolidated affiliate	340	125	1,064	579
Other, net	(1,105)	(1,717)	(4,051)	(5,487)
Total other income (expense)	5,842	4,834	15,057	10,896
Income before income taxes	92,897	71,743	275,951	248,888
Provision for income taxes	21,408	16,802	66,909	60,460
Net income	$ 71,489	$ 54,941	$ 209,042	$ 188,428
Net income per common share
Basic	$ 1.9	$ 1.47	$ 5.55	$ 5.03
Diluted	1.9	1.46	5.55	5.01
Cash dividends declared per common share	$ 0.74	$ 0.72	$ 2.22	$ 2.16
Weighted average shares outstanding
Basic	37,527	37,491	37,641	37,485
Diluted	37,608	37,574	37,696	37,603
Commissions [Member]
Revenues
Revenues	$ 180,392	$ 150,496	$ 536,944	$ 491,073
Information Services [Member]
Revenues
Revenues	12,960	11,801	37,385	34,466
Post-trade Services [Member]
Revenues
Revenues	10,382	9,833	31,512	29,228
Technology Services [Member]
Revenues
Revenues	$ 2,981	$ 154	$ 8,852	$ 532