Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Adjustments to reconcile net income to net cash (used in)/provided by operating activities:
Depreciation and amortization	$ 28,267,000	$ 23,843,000	$ 23,216,000
Amortization of loans and advances to financial advisors and other employees	55,923,000	50,162,000	33,408,000
Amortization of premium on available-for-sale securities	12,782,000	8,552,000	866,000
Provision for loan losses and allowance for loans and advances to financial advisors and other employees	2,243,000	123,000	298,000
Deferred income taxes	25,764,000	(54,213,000)	(10,270,000)
Stock-based compensation	26,411,000	190,731,000	47,962,000
Excess tax benefits from stock-based compensation	(24,863,000)	(17,487,000)	(13,337,000)
Gain on the sale of investments	1,877,000	(5,431,000)	14,303,000
Other, net	1,315,000	4,366,000	2,455,000
Decrease/(increase) in operating assets:
Cash segregated for regulatory purposes and restricted cash	5,982,000	(6,004,000)	21,000
Receivables:
Brokerage clients, net	(82,210,000)	(93,765,000)	(79,688,000)
Brokers, dealers and clearing organizations	18,395,000	63,132,000	(198,034,000)
Securities purchased under agreements to resell	48,162,000	1,237,000	(107,131,000)
Trading securities owned, including those pledged	(43,467,000)	25,316,000	(332,315,000)
Loans originated as mortgages held for sale	(1,060,457,000)	(1,130,528,000)	(874,786,000)
Proceeds from mortgages held for sale	1,013,515,000	1,104,317,000	848,045,000
Loans and advances to financial advisors and other employees	(46,426,000)	(46,376,000)	(108,327,000)
Other assets	14,842,000	22,473,000	(14,136,000)
Increase/(decrease) in operating liabilities:
Brokerage clients	33,244,000	(2,241,000)	58,388,000
Brokers, dealers and clearing organizations	(72,495,000)	13,251,000	62,181,000
Drafts	2,653,000	6,284,000	17,563,000
Trading securities sold, but not yet purchased	65,296,000	(77,230,000)	178,436,000
Other liabilities and accrued expenses	(70,310,000)	54,295,000	25,072,000
Net cash (used in)/provided by operating activities	45,888,000	142,232,000	(347,250,000)
Investing Activities:
Maturities, calls, sales, and principal paydowns on available-for-sale securities	654,958,000	309,646,000	49,259,000
Maturities, calls and principal paydowns on held-to-maturity securities	9,450,000
Sale or maturity of investments	76,263,000	105,703,000	57,515,000
Sale of bank branch		13,905,000
Sale of other real estate owned	929,000	2,099,000	3,734,000
Increase in bank loans, net	(243,592,000)	(55,214,000)	(2,626,000)
Payments for:
Purchase of available-for-sale securities	(895,391,000)	(747,376,000)	(568,910,000)
Purchase of held-to-maturity securities	(119,960,000)	(45,963,000)
Purchase of investments	(119,720,000)	(121,885,000)	(105,275,000)
Purchase of fixed assets	(59,730,000)	(27,736,000)	(27,892,000)
Purchase of other real estate owned	(474,000)	(744,000)	(4,966,000)
Acquisitions, net	(18,817,000)	(483,000)	(251,652,000)
Net cash used in investing activities	(716,084,000)	(568,048,000)	(850,813,000)
Financing Activities:
Net proceeds from short-term borrowings from banks	89,800,000	18,800,000	90,800,000
(Decrease)/increase in securities sold under agreements to repurchase	(29,419,000)	(12,938,000)	120,317,000
Increase in bank deposits, net	448,170,000	593,977,000	762,413,000
Increase/(decrease) in securities loaned	97,537,000	11,158,000	(1,412,000)
Excess tax benefits from stock-based compensation	24,863,000	17,487,000	13,337,000
Issuance of common stock		865,000	2,719,000
Repurchase of common stock	(48,505,000)	(91,769,000)
Reissuance of treasury stock	3,983,000	5,045,000	820,000
Extinguishment of Senior Notes		(23,000,000)
Payment of Federal Home Loan Bank advances		(2,000,000)	(4,000,000)
Extinguishment of subordinated debt	(1,284,000)	(1,840,000)	(1,300,000)
Net cash provided by financing activities	585,145,000	515,785,000	1,120,158,000
Effect of exchange rate changes on cash	(807,000)	1,740,000
Proceeds from Issuance or Sale of Equity			136,464,000
(Decrease)/increase in cash and cash equivalents	(85,858,000)	91,709,000	(77,905,000)
Supplemental disclosure of cash flow information:
Cash paid for interest	25,209,000.0	13,104,000.0	12,066,000.0
Cash paid for income taxes, net of refunds	5,547,000.0	54,984,000.0	15,617,000.0
Noncash investing and financing activities:
SubordinatedDebtClaims			3,166,000.0
PaymentofRyanBeckContingentEarn-out			9,301,000.0
CommonStockIssuanceStone&Youngber	6,100,000.0
CommonStockIssuanceTWPG		271,285,000.0
Unit issuances, net of forfeitures	$ 138,203,000.0	$ 157,546,000.0	$ 89,633,000.0