Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues:
Commissions	$ 674,418		$ 640,287		$ 518,803
Principal transactions	409,823		408,954		380,160
Investment banking	578,689		457,736		292,686
Asset management and service fees	386,001		305,639		257,981
Interest	185,969		142,539		108,705
Other income	14,785		64,659		69,148
Total revenues	2,249,685		2,019,814		1,627,483
Interest expense	41,261		46,368		33,370
Net revenues	2,208,424	[1]	1,973,446	[1]	1,594,113	[1]
Non-interest expenses:
Compensation and benefits	1,403,932		1,311,386		1,010,140
Occupancy and equipment rental	169,040		158,268		128,365
Communications and office supplies	106,926		99,726		79,406
Commissions and floor brokerage	36,555		37,225		29,610
Other operating expenses	201,177		181,612		116,845
Total non-interest expenses	1,917,630		1,788,217		1,364,366
Income from continuing operations before income tax	290,794		185,229		229,747
Provision for income taxes	111,664		12,322		84,451
Income from continuing operations	179,130		172,907		145,296
Discontinued operations:
Loss from discontinued operations, net of tax	(3,063)		(10,894)		(6,723)
Net income	$ 176,067		$ 162,013		$ 138,573
Earnings per basic common share
Income from continuing operations	$ 2.69		$ 2.72		$ 2.71
Loss from discontinued operations	$ (0.04)		$ (0.17)		$ (0.12)
Earnings per basic common share	$ 2.65		$ 2.55		$ 2.59
Earnings per diluted common share
Income from continuing operations	$ 2.35		$ 2.35		$ 2.31
Loss from discontinued operations	$ (0.04)		$ (0.15)		$ (0.11)
Earnings per diluted common share	$ 2.31		$ 2.20		$ 2.20
Weighted average number of common shares outstanding:
Basic	66,472		63,568		53,563
Diluted	76,376		73,504		62,937

[1] No individual client accounted for more than 10 percent of total net revenues for the years ended December 31, 2014, 2013, or 2012.