Consolidated Statements Of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Revenues:
Revenue from contracts with customers		$ 847,931	$ 633,108
Principal transactions		165,006	138,666
Interest		127,540	161,177
Other income		25,634	9,207
Total revenues		1,149,229	937,391
Interest expense		14,440	24,357
Net revenues	[1]	1,134,789	913,034
Non-interest expenses:
Compensation and benefits		697,914	577,179
Occupancy and equipment rental		72,032	66,073
Communications and office supplies		41,825	41,124
Commissions and floor brokerage		15,703	14,842
Provision for credit losses		(5,252)	16,068
Other operating expenses		84,675	82,642
Total non-interest expenses		906,897	797,928
Income from operations before income tax expense		227,892	115,106
Provision for income taxes		54,877	28,517
Net income		173,015	86,589
Preferred dividends		8,289	4,844
Net income available to common shareholders		$ 164,726	$ 81,745
Earnings per common share:
Basic		$ 1.53	$ 0.76
Diluted		1.40	0.71
Cash dividends declared per common share		$ 0.15	$ 0.11
Weighted-average number of common shares outstanding:
Basic		107,746	106,929
Diluted		117,875	114,929
Commissions [Member]
Revenues:
Revenue from contracts with customers		$ 213,614	$ 211,098
Investment Banking [Member]
Revenues:
Revenue from contracts with customers		339,288	179,468
Asset Management and Service Fees [Member]
Revenues:
Revenue from contracts with customers		$ 278,147	$ 237,775

[1] No individual client accounted for more than 10 percent of total net revenues for the three months ended March 31, 2021 or 2020.