Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Revenues
Revenues	$ 817,097	$ 752,547	$ 718,300
Expenses
Employee compensation and benefits	235,880	206,926	182,104
Depreciation and amortization	73,824	70,557	61,446
Technology and communications	72,166	62,801	52,964
Professional and consulting fees	27,382	31,935	33,949
Occupancy	14,690	14,216	14,121
Marketing and advertising	11,713	11,049	9,977
Clearing costs	17,863	17,002	17,663
General and administrative	22,709	23,042	19,200
Total expenses	476,227	437,528	391,424
Operating income	340,870	315,019	326,876
Other income (expense)
Interest income	26,046	22,425	5,040
Interest expense	(1,601)	(1,983)	(700)
Equity in earnings of unconsolidated affiliate	1,395	735	1,126
Other, net	(6,164)	(3,496)	5,946
Total other income (expense)	19,676	17,681	11,412
Income before income taxes and equity in undistributed earnings of subsidiaries	360,546	332,700	338,288
Provision for income taxes	86,365	74,645	88,064
Net income	$ 274,181	$ 258,055	$ 250,224
Net income per common share
Basic	$ 7.29	$ 6.87	$ 6.68
Diluted	7.28	6.85	6.65
Cash dividends declared per common share	$ 2.96	$ 2.88	$ 2.8
Weighted average shares outstanding
Basic	37,600	37,546	37,468
Diluted	37,672	37,654	37,643
Commissions [Member]
Revenues
Revenues	$ 711,710	$ 662,964	$ 641,183
Information Services [Member]
Revenues
Revenues	50,540	46,383	39,314
Post-trade Services [Member]
Revenues
Revenues	42,487	40,178	36,877
Technology Services [Member]
Revenues
Revenues	$ 12,360	$ 3,022	$ 926