Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Revenue from contracts with customers		$ 2,187,145
Principal transactions		351,378	$ 396,826	$ 475,428
Interest		646,449	454,381	294,332
Other income		25,553	37,524	46,798
Total revenues		3,194,957	2,996,462	2,642,370
Interest expense		170,076	70,030	66,874
Net revenues	[1]	3,024,881	2,926,432	2,575,496
Non-interest expenses:
Compensation and benefits		1,770,762	1,958,929	1,726,016
Occupancy and equipment rental		222,384	222,708	231,324
Communications and office supplies		140,254	133,493	139,644
Commissions and floor brokerage		41,967	44,132	44,315
Other operating expenses		315,152	297,634	291,615
Total non-interest expenses		2,490,519	2,656,896	2,432,914
Income before income tax expense		534,362	269,536	142,582
Provision for income taxes		140,394	86,665	61,062
Net income		393,968	182,871	81,520
Preferred dividends		9,375	9,375	3,906
Net Income available to common shareholders		$ 384,593	$ 173,496	$ 77,614
Earnings per common share:
Basic		$ 5.36	$ 2.53	$ 1.16
Diluted		$ 4.73	$ 2.14	$ 1.00
Weighted-average number of common shares outstanding:
Basic		71,786	68,562	66,871
Diluted		81,321	81,035	77,563
Cash dividends declared per common share		$ 0.48	$ 0.20	$ 0
Commissions [Member]
Revenues:
Revenue from contracts with customers		$ 657,732	$ 678,904	$ 729,989
Investment Banking [Member]
Revenues:
Revenue from contracts with customers		707,670	726,763	513,034
Asset Management and Service Fees [Member]
Revenues:
Revenue from contracts with customers		$ 806,175	$ 702,064	$ 582,789

[1] No individual client accounted for more than 10 percent of total net revenues for the years ended December 31, 2018, 2017, and 2016.