Bank Loans (Schedule Of Balance And Associated Percentage Of Each Major Loan Category In Bank Loan Portfolio) (Details) - USD ($) $ in Thousands		Sep. 30, 2015		Jun. 30, 2015	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans		$ 2,442,343			$ 2,116,634		$ 1,921,351
Unamortized loan discount		(994)			(30,533)
Unamortized loan fees, net of loan fees		(1,841)			(1,631)
Loans in process		(2,402)			1,681
Allowance for loan losses		(27,707)		$ (23,923)	(20,731)		(18,996)	$ (17,103)	$ (12,668)
Bank loans, net		$ 2,409,399			$ 2,065,420
Gross bank loans, Percent		100.00%			100.00%
Securities-based loans		$ 1,000,000			$ 732,800
Commercial And Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans		1,121,643			896,853		833,988
Allowance for loan losses		$ (22,414)		(19,297)	$ (16,609)		(15,903)	(13,557)	(9,832)
Gross bank loans, Percent		45.90%			42.40%
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans		$ 1,026,197	[1]		$ 758,288	[1]	638,810
Allowance for loan losses		$ (1,613)		(1,568)	$ (1,255)		(1,001)	(937)	(892)
Gross bank loans, Percent	[1]	42.00%			35.80%
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans		$ 260,958			$ 432,646		418,806
Allowance for loan losses		$ (1,122)		(904)	$ (787)		(674)	(713)	(408)
Gross bank loans, Percent		10.70%			20.40%
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans		$ 19,811			$ 15,902		15,971
Allowance for loan losses		$ (264)		(286)	$ (232)		(239)	(210)	(198)
Gross bank loans, Percent		0.80%			0.80%
Home Equity Lines Of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans		$ 11,260			$ 12,945		13,776
Allowance for loan losses		$ (253)		$ (265)	$ (267)		$ (274)	$ (131)	(174)
Gross bank loans, Percent		0.50%			0.60%
Construction And Land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans		$ 2,474
Allowance for loan losses		$ (47)							$ (12)
Gross bank loans, Percent		0.10%

[1] Includes securities-based loans of $ 1.0 billion and $732.8 million at September 30, 2015 and December 31, 2014, respectively.