Notes Payable, Federal Home Loan Bank Advances, Other Borrowings, Secured Borrowings And Subordinated Notes (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Oct. 28, 2011	Mar. 31, 2011
Debt Instrument [Line Items]
Notes payable	$ 52,639,000	$ 52,822,000		$ 1,000,000
Notes payable outstanding	51,000,000
Loan agreement with unaffiliated banks, amount	76,000,000
Revolving note	75,000,000
Revolving note maturity date, original	October 28, 2011
Credit facility, current	75,000,000
Incremental interest rate over base rate	1.30%
Percentage of commitment fee payment	0.50%
Federal Home Loan Bank advances, restructured advances	292,500,000
Federal Home Loan Bank advances, prepayment fees	22,400,000
Customer balances in sweep accounts	81,600,000
Short-term borrowings from brokers	302,500,000
Instruments issued by the securitization entity	600,000,000
Interest rate base point on notes	1.30%
Maturity Date	Dec. 15, 2013
Company repurchased notes	172,000,000
Total notes amount	428,000,000	600,000,000		600,000,000
Subordinated notes	35,000,000	35,000,000		50,000,000
Subordinated debt, annual principal payment	5,000,000
Restated credit agreement revolving credit facility, maturity date			October 26, 2012
Agreement [Member]
Debt Instrument [Line Items]
Notes payable	1,000,000
Interest rate on loan agreement	4.50%
Incremental interest rate over base rate	4.50%
Interest rate base point on notes	4.50%
Previous Borrowing Capacity [Member]
Debt Instrument [Line Items]
Credit facility, current			50,000,000
Line of credit facility, amount outstanding	50,000,000
Federal Funds Rate [Member]
Debt Instrument [Line Items]
Incremental interest rate over base rate	1.00%
Interest rate base point on notes	1.00%
Term Loan [Member]
Debt Instrument [Line Items]
Maturity Date	Jun. 01, 2015
Lender's Prime Rate [Member]
Debt Instrument [Line Items]
Incremental interest rate over base rate	0.50%
Interest rate base point on notes	0.50%
Eurodollar Rate [Member]
Debt Instrument [Line Items]
Incremental interest rate over base rate	1.50%
Interest rate base point on notes	1.50%
British Bankers Association's LIBOR Rate [Member]
Debt Instrument [Line Items]
Incremental interest rate over base rate	3.50%
Interest rate base point on notes	3.50%
Tangible Equity Units [Member]
Debt Instrument [Line Items]
Junior subordinated notes	44,700,000
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Incremental interest rate over base rate	1.63%
Junior subordinated amortizing notes interest rate	9.50%
Quarterly principal and interest payments	4,300,000
Initial payment of subordinated notes	4,600,000
Interest rate base point on notes	1.63%
Class A Notes [Member]
Debt Instrument [Line Items]
Incremental interest rate over base rate	1.45%
Instruments issued by the securitization entity	600,000,000
Interest rate base point on notes	1.45%
Maturity years	2.93
October 2002 [Member]
Debt Instrument [Line Items]
Subordinated notes	5,000,000
April 2003 [Member]
Debt Instrument [Line Items]
Subordinated notes	10,000,000
October 2005 [Member]
Debt Instrument [Line Items]
Subordinated notes	20,000,000
QSPE [Member]
Debt Instrument [Line Items]
Maturity Date	Feb. 17, 2014
Great Lakes Advisors [Member]
Debt Instrument [Line Items]
Notes payable outstanding	$ 1,600,000
Interest rate on loan agreement	1.25%
Incremental interest rate over base rate	1.00%
Interest rate base point on notes	1.00%