Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues:
Commissions	$ 127,966	$ 143,243	$ 378,696	$ 437,344
Principal transactions	102,979	76,650	310,776	249,250
Investment banking	72,938	37,673	210,739	143,509
Asset management and service fees	62,881	58,253	189,010	172,914
Interest	27,306	24,161	79,744	64,246
Other income	31,922	540	50,634	11,352
Total revenues	425,992	340,520	1,219,599	1,078,615
Interest expense	5,912	6,306	24,779	18,931
Net revenues	420,080	334,214	1,194,820	1,059,684
Non-interest expenses:
Compensation and benefits	267,652	210,573	761,730	671,678
Occupancy and equipment rental	33,061	30,914	96,172	89,962
Communications and office supplies	19,976	18,838	61,146	56,198
Commissions and floor brokerage	8,031	7,400	23,390	20,943
Other operating expenses	29,683	27,466	87,577	127,321
Total non-interest expenses	358,403	295,191	1,030,015	966,102
Income before income tax expense	61,677	39,023	164,805	93,582
Provision for income taxes	23,967	16,719	66,186	36,464
Net income	$ 37,710	$ 22,304	$ 98,619	$ 57,118
Earnings per common share:
Basic	$ 0.70	$ 0.43	$ 1.84	$ 1.09
Diluted	$ 0.60	$ 0.35	$ 1.57	$ 0.90
Weighted average number of common shares outstanding:
Basic	53,601	52,367	53,471	52,610
Diluted	63,054	63,152	62,817	63,174