Consolidated Statements Of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenue from contracts with customers		$ 876,248	$ 605,314	$ 1,724,179	$ 1,238,422
Principal transactions		152,597	166,017	317,603	304,683
Interest		133,591	128,368	261,131	289,545
Other income		13,235	21,514	38,869	30,721
Total revenues		1,167,314	908,901	2,316,543	1,846,292
Interest expense		14,178	13,084	28,618	37,441
Net revenues	[1]	1,153,136	895,817	2,287,925	1,808,851
Non-interest expenses:
Compensation and benefits		692,054	547,174	1,389,968	1,124,353
Occupancy and equipment rental		70,971	66,264	143,003	132,337
Communications and office supplies		41,308	43,046	83,133	84,170
Commissions and floor brokerage		13,977	15,177	29,680	30,019
Provision for credit losses		(9,652)	19,210	(14,904)	35,278
Other operating expenses		80,453	61,986	165,128	144,628
Total non-interest expenses		889,111	752,857	1,796,008	1,550,785
Income from operations before income tax expense		264,025	142,960	491,917	258,066
Provision for income taxes		65,948	35,073	120,825	63,590
Net income		198,077	107,887	371,092	194,476
Preferred dividends		8,289	4,843	16,578	9,687
Net income available to common shareholders		$ 189,788	$ 103,044	$ 354,514	$ 184,789
Earnings per common share:
Basic		$ 1.76	$ 0.97	$ 3.29	$ 1.74
Diluted		1.60	0.92	3.00	1.63
Cash dividends declared per common share		$ 0.15	$ 0.11	$ 0.30	$ 0.22
Weighted-average number of common shares outstanding:
Basic		107,837	105,791	107,795	106,358
Diluted		118,602	111,581	118,279	113,477
Commissions [Member]
Revenues:
Revenue from contracts with customers		$ 195,579	$ 177,028	$ 409,193	$ 388,126
Investment Banking [Member]
Revenues:
Revenue from contracts with customers		376,443	217,035	715,731	396,503
Asset Management and Service Fees [Member]
Revenues:
Revenue from contracts with customers		$ 295,869	$ 198,939	$ 574,016	$ 436,714

[1] No individual client accounted for more than 10 percent of total net revenues for the three and six months ended June 30, 2021 or 2020.