Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 67,466	$ 45,163
Provision	2,043	6,136
Charge-offs	(14)	(1)
Recoveries	2
Ending Balance	69,497	51,298
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	54,474	35,127
Provision	1,971	3,662
Charge-offs	(12)
Ending Balance	56,433	38,789
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	8,430	2,660
Provision	349	1,530
Ending Balance	8,779	4,190
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,088	3,094
Provision	(194)	299
Ending Balance	1,894	3,393
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,520	1,363
Provision	(200)	255
Ending Balance	1,320	1,618
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	162	371
Provision	1	(85)
Charge-offs		(1)
Recoveries	1
Ending Balance	164	285
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	100	232
Provision	99	205
Ending Balance	199	437
Consumer [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	16	129
Provision		(22)
Charge-offs	(2)
Recoveries	1
Ending Balance	15	107
Qualitative [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	676	2,187
Provision	17	292
Ending Balance	$ 693	$ 2,479