Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 69,497	$ 51,298	$ 67,466	$ 45,163
Provision	4,277	5,856	6,320	11,991
Charge-offs		(2,953)	(14)	(2,953)
Recoveries	1	1	3	1
Ending Balance	73,775	54,202	73,775	54,202
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	56,433	38,789	54,474	35,127
Provision	3,139	2,266	5,110	5,928
Charge-offs		(250)	(12)	(250)
Ending Balance	59,572	40,805	59,572	40,805
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,894	3,393	2,088	3,094
Provision	34	207	(160)	506
Ending Balance	1,928	3,600	1,928	3,600
Consumer [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	15	107	16	129
Provision	(2)	(2)	(2)	(24)
Charge-offs			(2)
Recoveries			1
Ending Balance	13	105	13	105
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	8,779	4,190	8,430	2,660
Provision	549	1,379	898	2,909
Ending Balance	9,328	5,569	9,328	5,569
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,320	1,618	1,520	1,363
Provision	352	2,017	152	2,272
Charge-offs		(2,703)		(2,703)
Ending Balance	1,672	932	1,672	932
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	164	285	162	371
Provision	64	(3)	65	(89)
Recoveries	1	1	2	1
Ending Balance	229	283	229	283
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	199	437	100	232
Provision	104	(213)	203	(8)
Ending Balance	303	224	303	224
Qualitative [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	693	2,479	676	2,187
Provision	37	205	54	497
Ending Balance	$ 730	$ 2,684	$ 730	$ 2,684