Consolidated Statements Of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Revenues:
Revenue from contracts with customers	[1]	$ 531,349			$ 1,073,005
Principal transactions		88,984		$ 95,703	186,766		$ 212,560
Interest		154,421		108,951	292,155		209,904
Other income		9,073		7,198	12,430		15,950
Total revenues		780,011		742,291	1,556,822		1,433,718
Interest expense		37,279		16,644	63,732		32,540
Net revenues	[2]	742,732		725,647	1,493,090		1,401,178
Non-interest expenses:
Compensation and benefits		442,170		453,876	900,063		890,263
Occupancy and equipment rental		53,596		57,892	111,191		110,437
Communications and office supplies		36,639		34,192	70,138		68,036
Commissions and floor brokerage		10,095		11,232	19,460		21,955
Other operating expenses		81,885		85,257	154,337		148,270
Total non-interest expenses		624,385		642,449	1,255,189		1,238,961
Income from operations before income tax expense		118,347		83,198	237,901		162,217
Provision for income taxes		31,060		30,387	61,853		43,894
Net income		87,287		52,811	176,048		118,323
Preferred dividends		2,344		2,344	4,688		4,688
Net income available to common shareholders		$ 84,943		$ 50,467	$ 171,360		$ 113,635
Earnings per common share:
Basic		$ 1.18		$ 0.74	$ 2.39		$ 1.66
Diluted		$ 1.04		$ 0.63	$ 2.10		$ 1.41
Weighted-average number of common shares outstanding:
Basic		71,692		68,556	71,843		68,471
Diluted		81,299		80,021	81,548		80,391
Cash dividends declared per common share		$ 0.12			$ 0.24		$ 0
Commissions [Member]
Revenues:
Revenue from contracts with customers		$ 166,902		$ 172,264	$ 332,677		$ 347,538
Investment Banking [Member]
Revenues:
Revenue from contracts with customers		161,063		185,261	337,425		312,113
Asset Management and Service Fees [Member]
Revenues:
Revenue from contracts with customers		$ 199,568	[1]	$ 172,914	$ 395,369	[1]	$ 335,653

[1] Excludes revenue included in the Other segment.

[2] No individual client accounted for more than 10 percent of total net revenues for the three and six months ended June 30, 2018 or 2017.