Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 51,298	$ 34,050	$ 45,163	$ 29,787
Provision	5,856	1,824	11,991	6,082
Charge-offs	(2,953)	(13)	(2,953)	(13)
Recoveries	1	5	1	10
Ending Balance	54,202	35,866	54,202	35,866
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	38,789	27,700	35,127	24,748
Provision	2,266	2,116	5,928	5,068
Charge-offs	(250)		(250)
Ending Balance	40,805	29,816	40,805	29,816
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	3,393	1,605	3,094	1,607
Provision	207	126	506	124
Ending Balance	3,600	1,731	3,600	1,731
Consumer [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	107	84	129	105
Provision	(2)	23	(24)	2
Ending Balance	105	107	105	107
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	4,190	1,330	2,660	1,241
Provision	1,379	210	2,909	298
Charge-offs		(13)		(13)
Recoveries		2		3
Ending Balance	5,569	1,529	5,569	1,529
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,618	1,289	1,363	264
Provision	2,017	(780)	2,272	241
Charge-offs	(2,703)		(2,703)
Recoveries		3		7
Ending Balance	932	512	932	512
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	285	267	371	290
Provision	(3)	16	(89)	(7)
Recoveries	1		1
Ending Balance	283	283	283	283
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	437	118	232	78
Provision	(213)	26	(8)	66
Ending Balance	224	144	224	144
Qualitative [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,479	1,657	2,187	1,454
Provision	205	87	497	290
Ending Balance	$ 2,684	$ 1,744	$ 2,684	$ 1,744