Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenues
Revenues	$ 718,300	$ 698,951	$ 689,125
Expenses
Employee compensation and benefits	182,104	170,916	156,885
Depreciation and amortization	61,446	53,447	35,996
Technology and communications	52,964	42,474	34,092
Professional and consulting fees	33,949	41,925	32,304
Occupancy	14,121	13,320	13,425
Marketing and advertising	9,977	9,059	7,940
Clearing costs	17,663	16,074	21,058
General and administrative	19,200	14,501	12,697
Total expenses	391,424	361,716	314,397
Operating income (loss)	326,876	337,235	374,728
Other income (expense)
Interest income	5,040	401	2,446
Interest expense	(700)	(842)	(1,142)
Equity in undistributed income of subsidiaries	1,126	0	0
Other, net	5,946	(2,871)	(1,673)
Total other income (expense)	11,412	(3,312)	(369)
Income before income taxes	338,288	333,923	374,359
Provision for income taxes	88,064	76,035	74,982
Net income	$ 250,224	$ 257,888	$ 299,377
Net income per common share
Basic	$ 6.68	$ 6.88	$ 8.01
Diluted	6.65	6.77	7.85
Cash dividends declared per common share	$ 2.80	$ 2.64	$ 2.40
Weighted average shares outstanding
Basic	37,468,000	37,508,000	37,359,000
Diluted	37,643,000	38,097,000	38,144,000
Commissions [Member]
Revenues
Revenues	$ 641,183	$ 621,008	$ 634,445
Information Services [Member]
Revenues
Revenues	39,314	38,175	34,341
Post-trade Services [Member]
Revenues
Revenues	36,877	38,922	19,460
Other [Member]
Revenues
Revenues	$ 926	$ 846	$ 879